Thèses : « Stress response protein p66ShcA »

1

Covington, Sean M. « The Stress Protein Response of Pimephales promelas to Copper ». Thesis, University of North Texas, 1992. https://digital.library.unt.edu/ark:/67531/metadc500868/.

Texte intégral

Résumé :

Organisms synthesize stress proteins in response to a variety of stressors. The 68/70-kDa proteins (synonymous to the 72/73-kDa proteins) have shown to be the most promising stress proteins, and have been proposed as a biomarker of general organismal stress. The 68/70-kDa proteins were used in an antigen/antibody based approach to determine the duration of the stress protein response of Pimephales promelas following an acute exposure to copper sulphate.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Gonçalves, Nuno M. « Insights into the rice response to abiotic stress : ». Doctoral thesis, Universidade Nova de Lisboa, Instituto de Tecnologia Química e Biológica António Xavier, 2019. http://hdl.handle.net/10362/95814.

Texte intégral

Résumé :

"Abiotic stress is one of the biggest threats to food security worldwide, enhanced by a changing global climate and the alarming gap in crop productivity to face population growth. Rice (Oryza sativa) is one of the top staple food crops worldwide, along with wheat and maize, and is also one of the most susceptible monocots to abiotic stress, such as salinity, with moderate stress leading to up to 90% production losses."
N/A

Styles APA, Harvard, Vancouver, ISO, etc.

3

Fogl, Claudia Liliane Fiona. « Structure and function of the cardiac stress response protein MS1 ». Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/9408.

Texte intégral

Résumé :

Myocyte Stress 1 (ms1)/Striated muscle Activator of Rho Signalling (STARS), also known as Actin Binding Rho Activator (ABRA), is a 375 amino acid protein. Its expression increases one hour after the induction of stress in rat hearts through aortic banding. This expression precedes that of early response genes such as c-fos and c-jun. This process has been implicated in the development of left ventricular hypertrophy. ms1/STARS binds to actin, and deletion mutations had shown that residues 234-375 were necessary for actin binding. A mixture of combinatorial domain hunting and rational domain design gave a series of possible domains. Circular dichroism and nuclear magnetic resonance spectroscopy were used to characterise these domains. The first three domains, MSD1 (residues 2-118), MSD2 (40-196) and actin binding domain 1 (ABD1, 193-296) were unfolded, while ABD2 (294-375) was folded. Actin co-sedimentation assays showed that only ABD1 and ABD2 bound to actin. They bound to actin independently. The structure of ABD2 was determined using NMR. Mutation studies, based on the NMR structure and on data about the conservation of positively-charged regions in ms1/STARS homologues, were used to identify the actin binding surface of ABD2. The structure of ABD2 was shown to be a winged helix-turn-helix domain. These domains are often DNA binding domains. When DNA binding was attempted, it was shown that ABD1, ABD2 and the tandem of ABD1 and ABD2 bound to DNA. The identification of the actin binding domain and the discovery of a novel DNA binding ability open up many more possible functions of ms1/STARS.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Malakasi, Panagiota. « The regulation of oxidative stress response by a conserved response regulator protein in yeast ». Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273360.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

5

Jenkins, Mark 1979. « A role for the Drosophila eIF4E binding protein during stress response / ». Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82256.

Texte intégral

Résumé :

The Drosophila melanogaster eIF4E binding protein (d4E-BP) inhibits translation initiation and is implicated in cell growth as a downstream effector of the Drosophila insulin signaling pathway. Since d4E-BP null flies show similar growth and development to control flies, the possibility of a conditional phenotype was explored through stress treatments. Adult d4E-BP null flies show sensitivity to oxidative stress, and d4E-BP null larvae die faster than controls under starvation and protein starvation. Expressing a mutant d4E-BP that doesn't bind to eIF4E in the d4E-BP null background does not rescue this stress sensitivity, which suggests that wild-type stress resistance requires binding of d4E-BP to eIF4E.
The Drosophila forkhead transcription factor dFOXO is a transcriptional activator of d4E-BP. There is a strong reduction of d4E-BP peptide in a dFOXO null background. dFOXO null flies are also sensitive to oxidative stress, and rescue of this sensitivity through ectopic expression of UAS-d4E-BP(wt) in a dFOXO null background suggests d4E-BP is a downstream mediator of dFOXO oxidative stress resistance.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Mahmood, Ahsan. « Role of SLMAP in Endoplasmic Reticulum Stress and Unfolded Protein Response ». Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24399.

Texte intégral

Résumé :

Cardiac function is regulated by the molecular components of the sarco/endoplasmic reticulum (ER/SR). Disruptions in homeostatic balance of these proteins and calcium regulation results in activation of ER stress response. Sarcolemmal membrane-associated proteins (SLMAPs) are found in cell membrane, SR/ER, and mitochondria. Overexpression of SLMAP in the myocardium has shown to impair excitation-contraction (E-C) coupling in the transgenic (Tg) mice. ER stress response was examined in Tg mice overexpressing SLMAP in the myocardium. In Tg hearts, changes observed in the expression of proteins involved in ER stress were dependent on the age and sex. SLMAP overexpression results in maladaptive ER stress response, as the mice age. Neonatal cardiomyocytes isolated from the Tg hearts showed decreased viability, upregulation of ER stress response proteins, which were sensitized to thapsigargin-induced stress, and desensitized to palmitate-induced oxidative stress. These findings suggest that normal SLMAP levels are important for proper cardiac function, and cell viability.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Hearne, Catherine Mary. « A study of the heat shock response of Bacillus subtilis ». Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334111.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

8

Chalmers, Fiona. « Improving protein yield from mammalian cells by manipulation of stress response pathways ». Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7666/.

Texte intégral

Résumé :

Monoclonal antibodies are a class of therapeutic that is an expanding area of the lucrative biopharmaceutical industry. These complex proteins are predominantly produced from large cultures of mammalian cells; the industry standard cell line being Chinese Hamster Ovary (CHO) cells. A number of optimisation strategies have led to antibody titres from CHO cells increasing by a hundred-fold, and it has been proposed that a further bottleneck in biosynthesis is in protein folding and assembly within the secretory pathway. To alleviate this bottleneck, a CHO-derived host cell line was generated by researchers at the pharmaceutical company UCB that stably overexpressed two critical genes: XBP1, a transcription factor capable of expanding the endoplasmic reticulum and upregulating protein chaperones; and Ero1α, an oxidase that replenishes the machinery of disulphide bond formation. This host cell line, named CHO-S XE, was confirmed to have a high yield of secreted antibody. The work presented in this thesis further characterises CHO-S XE, with the aim of using the information gained to lead the generation of novel host cell lines with more optimal characteristics than CHO-S XE. In addition to antibodies, it was found that CHO-S XE had improved production of two other secreted proteins: one with a simple tertiary structure and one complex multi-domain protein; and higher levels of a number of endogenous protein chaperones. As a more controlled system of gene expression to unravel the specific roles of XBP1 and Ero1α in the secretory properties of CHO-S XE, CHO cells with inducible overexpression of XBP1, Ero1α, or a third gene involved in the Unfolded Protein Response, GADD34, were generated. From these cell lines, it was shown that more antibody was secreted by cells with induced overexpression of XBP1; however, Ero1α and GADD34 overexpression did not improve antibody yield. Further investigation revealed that endogenous XBP1 splicing was downregulated in the presence of an abundance of the active form of XBP1. This result indicated a novel aspect of the regulation of the activity of IRE1, the stress-induced endoribonuclease responsible for XBP1 splicing. Overall, the work described in this thesis confirms that the overexpression of XBP1 has an enhancing effect on the secretory properties of CHO cells; information which could contribute to the development of host cells with a greater capacity for antibody production.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Muthevhuli, Mpho. « Investigation of the role of AtNOGC1, a guanylyl cyclase protein in response to abiotic and biotic stress ». University of the Western Cape, 2018. http://hdl.handle.net/11394/6763.

Texte intégral

Résumé :

>Magister Scientiae - MSc
Agricultural production is one of the most important sectors which provide food for the growing world population which is estimated to reach 9.7 billion by 2050, thus there is a need to produce more food. Climate change, on the other hand, is negatively affecting major global crops such as maize, sorghum, wheat and barley. Environmental factors such as salinity, drought, high temperatures and pathogens affect plant production by oxidatively damaging the physiological processes in plants, leading to plant death. Poor irrigation used to combat drought result in salinasation, which is estimated to affect 50% of arable land by 2050. Plants have developed several mechanisms that protect them against stress and these include overexpression of stress responsive genes and altered signal transduction to change the expression of stress responsive genes, among others. Cyclic 3’5’ guanosine monophosphate (cGMP), a second messenger that is synthesised by guanylyl cyclase (GC), transmit signals to various cellular functions in plants during plant development, growth and response to abiotic and biotic stresses. Arabidopsis thaliana nitric oxide guanylyl cyclase 1 (AtNOGC1) is a guanylyl cyclase which upon activation by nitric oxide (NO) leads to the production of more cGMP. Cyclic GMP further activates protein kinases, ion gated channels and phosphodiesterase which mediate response to various stresses. In this project the role of AtNOGC1 was investigated in response to abiotic and biotic stresses through analysis of its evolutionary relationships, promoter, gene expression and functional analysis via the viability assays in Escherichia coli (E.coli). Phylogenetic tree, exon-intron structure and conserved motifs were analysed using the Molecular Evolutionary Genetics Analysis (MEGA V.7), Gene Structure Display Server 2.0 (GSDS 2.0), and Multiple Expectation Maximisation for Motif Elicitation (MEME) tools respectively. AtNOGC1’s gene expression was analysed by the Real-Time Quantitative Reverse Transcription Polymerase Reaction (qRT-PCR), whereas functional analysis was carried out using the cell viability (liquid and spot) assays to determine its ability to confer stress tolerance to E. coli.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Nájar, Durán Elena. « Characterization of the maize protein ZmSTOP1 and its role in drought stress response ». Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/327875.

Texte intégral

Résumé :

El déficit hídrico se ha convertido un una gran amenaza hacia la producción agrícola en todo el mundo. La identificación de nuevos actores en la respuesta al estrés por sequía en plantas cultivables es vital para entender su adaptación a crecientes cambios ambientales. El ácido abscísico (ABA) es una hormona vegetal que media las respuestas adaptativas a la sequía, como la dormancia de semillas, el cierre estomático y la detención del crecimiento de la raíz. En el caso de la regulación estomática, el ABA activa la quinasa OST1, que a su vez fosforila diferentes sustratos, por ejemplo NADPH oxidasas, canales iónicos y factores de transcripción, lo que al final conducirá al cierre estomático. Aunque el cierre estomático en respuesta a ABA es esencial para evitar la desecación y, por lo tanto, la muerte de la planta, se debe mantener un cierto nivel de conductividad estomática para permitir el intercambio de gases y la transpiración, esencial para la captación de agua y solutos a través de las raíces. Hemos identificado y caracterizado un nuevo posible factor de transcripción dedo de zinc de tipo C2H2, homólogo a la proteína de Arabidopsis Sensitive to Proton Rhizotoxicity (STOP)1, la cual es crítica para la tolerancia a aluminio y protones en suelos ácidos. Hemos determinado que ZmSTOP1 es una proteína muy bien conservada entre especies, especialmente en sus cuatro dominios de tipo dedo de zinc, los cuales son característicos de las proteínas de tipo STOP1 en las plantas. ZmSTOP1 es miembro de una familia de cinco proteínas tipo STOP1 en maíz. Presenta localización nuclear y tiene la capacidad de unir ADN, aunque no se han podido identificar dianas específicas. En este trabajo mostramos cómo ZmSTOP1 complementa el fenotipo característico de AtSTOP1 en condiciones de pH ácido. Además, detectamos que la sobreexpresión de ZmSTOP1 promueve una respuesta diferencial a ABA en raíces y hojas. El crecimiento de raíces está sobre inhibido, mientras que los estomas presentan insensibilidad a la señal de ABA, permaneciendo más abiertos que el control tras un tratamiento con ABA. Utilizando un análisis por microarray hemos podido determinar que los genes afectados por ZmSTOP1 se clasifican principalmente en señalización, regulación de la transcripción y estrés. Su sobreexpresión promueve cambios en el patrón de expresión de varios genes importantes para la homeostasis iónica y la señalización celular, como el canal de potasio KT2/3, el transportador de calcio CAX7, la NADPH oxidasa RBOHD, o la ATPasa de protones de membrana plasmática HA2, y puede inducir la expresión ectópica de estos genes en raíces u hojas. La desregulación de estos genes puede afectar el comportamiento global de la planta ante condiciones de estrés por sequía, ya que los efectos del ABA dependen profundamente en la homeostasis iónica, pudiendo representar una posible explicación para los fenotipos observados. Adicionalmente, hemos establecido que esta proteína es interactor y sustrato de la quinasa OST1. La fosforilación por parte de esta quinasa modula el efecto de ZmSTOP1 en la regulación estomática. En resumen, con la caracterización de la proteína ZmSTOP1 hemos arrojado luz sobre la compleja red que regula la tolerancia a estrés en una planta crucial para el consumo humano y animal como es el maíz. Estos resultados pueden ser importantes para enfocar futuras mejoras genéticas de la planta, ya sea por ingeniería genética o mediante mejora clásica.
Water deficit has become a very important threat to agricultural yield worldwide. The identification of new players in drought stress response among crop plants is vital to understand their adaptation to increasing environmental challenges. Abscisic acid (ABA) is a plant hormone known to mediate drought adaptative responses such as seed dormancy, stomatal closure and root growth arrest. In the case of stomatal regulation, ABA drives the activation of OST1 kinase, which phosphorylates different substrates, for example NADPH oxidases, ionic channels and transcription factors, which will finally lead to stomatal closure. Although stomatal closure in response to ABA is essential to avoid desiccation, and thus, the death of the plant, a certain level of stomatal conductivity must be maintained to permit gas exchange and transpiration, essential to drive water and solutes uptake through the roots. We identified and characterized a new maize C2H2 zinc-finger putative transcription factor that presents homology to the Arabidopsis Sensitive to Proton Rhizotoxicity (STOP)1, which is critical for aluminum and proton tolerance in acidic soils. We determined that ZmSTOP1 is a well-conserved protein between plant species, especially in its four zinc-finger domains, which are characteristic of the STOP1-like proteins in plants. ZmSTOP1 is one of a five-members family of STOP1-like proteins in maize. It localizes in the nucleus, and has the ability to bind DNA, though no specific DNA targets were identified. In this work we show how ZmSTOP1 can complement AtSTOP1 phenotype in low pH conditions. Moreover, we detected that ZmSTOP1 overexpression promotes a differential response to ABA in roots and shoots. Root growth is over-inhibited whereas stomata present insensitivity to the ABA signal, remaining more open than the wild type after ABA treatment. Through microarray analyses we determine that the genes affected by ZmSTOP1 are classified mainly in signaling, regulation of transcription and stress. Its overexpression promotes changes in the expression pattern of several genes that are important for ionic homeostasis and signaling in cells, like the potassium channel KT2/3, the calcium transporter CAX7, the NADPH oxidase RBOHD, or the plasma membrane proton pump ATPase HA2, and it can induce ectopic expression of these genes in roots or shoots. The deregulation of these genes can affect the global behavior of the plant before drought stress conditions, as ABA effects depend deeply on ionic homeostasis, and could represent a possible explanation for the phenotypes observed. Additionally, we established that this protein is an interactor and a substrate of OST1 kinase. The phosphorylation by this kinase modulates ZmSTOP1 effect on stomatal regulation. In summary, by characterizing ZmSTOP1 protein we have shed light into the complex network regulating drought tolerance in a crucial plant for human and animal consumption like maize. These results can be important for focusing further genetic improvement of the plant, by either genetic engineering or classic breeding.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Liu, Fenglong. « Calcium-dependent protein kinase regulates soybean serine acetyltransferase in response to oxidative stress ». [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE0000561.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

12

Toman, Ondřej. « Stress response in Bacillus subtilis : signalization, adaptation and the role of protein L24 ». Paris 11, 2006. http://www.theses.fr/2006PA112175.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

13

Manza, Linda Lee. « Characterization of Protein Sumoylation in Response to Alkylation Stress in HEK 293 Cells ». Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/193944.

Texte intégral

Résumé :

Stress conditions such as heat shock, UV, alkylating agents, and H2O2 have been shown to result in the modification of a variety of protein targets via the production of reactive electrophiles. These modifications can directly impact protein function or can alter posttranslational modifications, thus leading to a disruption of cellular regulatory processes. Recent studies have shown that stress-induced protein modifications can modulate posttranslational modification by the small ubiquitin related modifier (SUMO) family of proteins. Unlike ubiquitination, which primarily targets proteins for proteasomal degradation, sumoylation exerts a variety of effects including protein stabilization, subcellular localization, and the alteration of protein-protein interactions and transcriptional activity. To investigate the effects of alkylation and oxidative stress on sumoylation, HEK293 cells were treated with iodoacetamide, hydroquinone, benzoquinone, Texas Red C5 bromoacetamide, hydrogen peroxide, and 4-hydroxynonenal (HNE), a highly reactive product of lipid peroxidation associated with oxidative stress. Western blot analysis revealed that the agents tested resulted in concentration-dependent changes in the patterns of SUMO-1 and SUMO-2/3 protein conjugation. Localization studies using western blot analysis and confocal immunofluorescence microscopy demonstrated that SUMO-1 protein conjugates were located primarily in the nucleus, whereas SUMO-2/3 protein conjugates were more equally distributed between the nucleus and the cytoplasm. SUMO-associated proteins were harvested from vehicle- and HNE-treated non-transfected HEK293 cells using agarose conjugated anti-SUMO-1 antibodies or from HA-SUMO-1- and HA-SUMO-3-expressing HEK293 cells using immunoaffinity chromatography. Multidimensional liquid chromatography-tandem mass spectrometry analyses resulted in the identification of 54 HA-SUMO-1-associated proteins and 37 HA-SUMO-3-associated proteins in vehicle-treated cells and 21 HA-SUMO-1- and HA-SUMO-3-associated proteins in HNE treated cells. Additionally, 27 SUMO-1-associated proteins were identified in the HNE-treated non-transfected cells. The functional classes of proteins targeted included RNA binding and processing proteins, metabolic enzymes, cytoskeletal regulators, and chaperone proteins. HNE treatment resulted in a near complete redistribution of both SUMO-1 and SUMO-3 to different targets. There was a 15% overlap in SUMO-1 and SUMO-3 associated proteins in vehicle-treated cells and a 10% overlap in HNE-treated cells indicating that SUMO proteins target distinct protein groups. These results indicate that protein modifying reactive electrophiles can regulate protein functions through the indirect alteration of endogenous posttranslational modifications.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Mutavchiev, Delyan Rumenov. « Regulation of fission yeast cell polarity by stress-response pathways ». Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29006.

Texte intégral

Résumé :

Cell polarisation is a key biological process crucial for the functioning of essentially all cells. Regulation of cell polarity is achieved through various processes determined by both internal and external factors. An example of the latter is that cell polarity can be disrupted or lost as a consequence of a variety of external stresses. When facing such stresses, cells adapt to unfavourable conditions by activating a range of molecular signalling pathways, collectively termed ‘stress response’. Despite the connections between external stress and cell polarity, whether stress-response signalling regulates cell polarisation and what the molecular basis for such regulation remains an open question. The fission yeast Schizosaccharomyces pombe presents an excellent biological platform to study the complexity of cell polarity regulation on a systematic level. This study is aimed at understanding the functional relationship between stress-response signalling and maintenance of cell polarity in this model organism. The findings presented in this thesis set the basis for establishing a functional link between the activation of the S.pombe stress-response pathway and the activity of the master regulator of cell polarity- the Rho GTPase Cdc42. Here, I describe experiments that identify an active involvement of the stress-response mitogen-activated kinase (MAPK) Sty1 in the dispersal of active Cdc42 from the sites of growth. This new role for Sty1 occurs independently from its involvement in transcription regulation and other previously identified signalling pathways involving Sty1. Furthermore, I also find that Sty1’s involvement in Cdc42 regulation has direct implications for fission yeast physiology as it is essential for the maintenance of cellular quiescence upon nitrogen starvation. This thesis also focuses on identifying the targets of Sty1 orchestrating the active Cdc42 disruption. Here, I describe a candidate-based approach, where I investigate the role of proteins from the Cdc42 regulatory network during Sty1 activation. Additionally, I present a global phospho-proteomics approach to identify novel targets of Sty1 and offer preliminary findings which might explain Sty1’s involvement in Cdc42 regulation.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Naim, Adnan. « The Role of G3BPs in the Stress Response Pathway ». Thesis, Griffith University, 2016. http://hdl.handle.net/10072/367499.

Texte intégral

Résumé :

The ras-GTPase SH3-domain Binding Proteins (G3BP) are a family of RNA-binding proteins that have been implicated in multiple cellular activities ranging from signal transduction to regulation of messenger RNA (mRNA). G3BPs were named after their interaction with the SH3 domain of Ras-GTPase-activating protein; however recent research did not find this interaction. All three members of the G3BPs family, G3BP1, G3BP2a and G3BP2b, share structural similarities with each other by having four distinct regions (1) the Nuclear Transporting Factor 2, (NTF2) domain at the N-terminal, (2) the acidic and proline-rich domain in the centre, (3) the RNA recognition motif (RRM) and (4) the arginine glycine (RGG)-rich region rich at the C-terminal. The presence of the NTF2 domain in its structure suggests G3BP might play a role in nucleocytoplasmic transportation, which was observed after serum stimulation where G3BP1 was translocated to the nucleus from the cytoplasm. The RNA recognition motif (RRM) region plays a vital role in its interaction with the target RNA. The RGG-rich box is a region rich in arginine and glycine residues, which plays a role assisting RRM in interactions with protein or RNA. G3BP1 is found to be overexpressed in many cancers, including breast cancer, and head and neck tumours, as well as cell lines derived from human lung, prostrate, colon, thyroid and breast cancer. G3BPs have also been implicated in translational control within differentiating neurons, suggesting that G3BP may play several roles in controlling the translational fate of its cargo and that its role may be cell-specific. G3BP1 has also been found in β-integrin- induced adhesion complexes. This information highlights G3BPs as a dynamic protein that is involved in several biological functions.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
Full Text

Styles APA, Harvard, Vancouver, ISO, etc.

16

Willis, William L. « YB-1 Stress-Response Protein Conformation Implicated in Post-transcriptional Control of Myofibroblast Differentiation ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376593223.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

17

DuRose, Jenny Bratlien. « The unfolded protein response integrating stress signals from the endoplasmic reticulum to the nucleolus / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3330123.

Texte intégral

Résumé :

Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed November 13, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Styles APA, Harvard, Vancouver, ISO, etc.

18

DeAngelis, Cara Marie. « Characterization of the Vibrio cholerae Phage Shock Protein Response ». University of Toledo Health Science Campus / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=mco1556723496251854.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

Sama, Reddy Ranjith Kumar. « FUS/TLS in Stress Response - Implications for Amyotrophic Lateral Sclerosis : A Dissertation ». eScholarship@UMMS, 2014. http://escholarship.umassmed.edu/gsbs_diss/704.

Texte intégral

Résumé :

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease is a fatal neurodegenerative disease. ALS is typically adult onset and is characterized by rapidly progressive loss of both upper and lower motor neurons that leads to death usually within 3-5 years. About 90% of all the cases are sporadic with no family history while the remaining 10% are familial cases with mutations in several genes including SOD1, FUS/TLS, TDP43 and C9ORF72. FUS/TLS (Fused in Sarcoma/Translocated in Liposarcoma or FUS) is an RNA/DNA binding protein that is involved in multiple cellular functions including DNA damage repair, transcription, mRNA splicing, RNA transport and stress response. More than 40 mutations have now been identified in FUS that account for about 5% of all the familial cases of ALS. However, the exact mechanism by which FUS causes ALS is unknown. While significant progress has been made in understanding the disease mechanism and identifying therapeutic strategies, several questions still remain largely unknown. The work presented here aims at understanding the normal functions of FUS as well as the pathogenic mechanisms by which it leads to disease. Several studies showed the association of mutant-FUS with structures made up of RNA and proteins, called stress granules that form under various stress conditions. However, little is known about the role of endogenous FUS under stress conditions. I have shown that under hyperosmolar conditions, the predominantly nuclear FUS translocates into the cytoplasm and incorporates into stress granules. The response is specific to hyperosmolar stress because FUS remains nuclear under other stress conditions tested, such as oxidative stress, ER stress and heat shock. The response of FUS is rapid, and cells with reduced FUS levels are susceptible to the hyperosmolar stress, indicating a pro-survival role for FUS. In addition to investigating the functions of endogenous wild-type (WT) FUS, the work presented also focuses on identifying the pathogenic mechanism(s) of FUS variants. Using various biochemical techniques, I have shown that ALS-causing FUS variants are misfolded compared to the WT protein. Furthermore, in a squid axoplasm based vesicle motility assay, the FUS variants inhibit fast axonal transport (FAT) in a p38 MAPK dependent manner, indicating a role for the kinase in mutant-FUS mediated disease pathogenesis. Analysis of human ALS patient samples indicates higher levels of total and phospho p38, supporting the notion that aberrant regulation of p38 MAPK is involved in ALS. The results presented in this dissertation 1) support a novel prosurvival role for FUS under hyperosmolar stress conditions and, 2) demonstrate that protein misfolding and aberrant kinase activation contribute to ALS pathogenesis by FUS variants.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Brickman, Todd. « The Heat Shock Protein 70 Response to Acute and Endurance Exercise ». University of Toledo Health Science Campus / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=mco1177608338.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

21

Arensdorf, Angela Marie. « The Mechanisms and Consequences of Gene Suppression During the Unfolded Protein Response ». Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4816.

Texte intégral

Résumé :

The endoplasmic reticulum (ER) facilitates the synthesis, assembly and quality control of all secretory, transmembrane, and resident proteins of the endomembrane system. An accumulation of unfolded proteins or a disruption in the specialized folding environment within the organelle causes ER stress, thus impairing the folding capacity of the ER. In response to this stress, the ER initiates a signaling cascade called the unfolded protein response (UPR) in an attempt to restore ER homeostasis. The vertebrate UPR is propagated by three ER-resident transmembrane proteins (i.e., PERK, IRE1α, and ATF6α), each initiating a signaling cascade that ultimately culminates in production of a transcriptional activator. The UPR was originally characterized as a pathway for the upregulation of ER chaperones, and a comprehensive body of subsequent work has shown that protein synthesis, folding, oxidation, trafficking, and degradation are all transcriptionally enhanced by the UPR. However, UPR activation is also accompanied by extensive mRNA suppression. The mechanisms responsible for this suppression and its consequences for physiological processes beyond the realm of ER protein folding and processing are only now beginning to be described. The overall goal of my thesis work was to explore this process of UPR-mediated gene suppression by identifying the mechanisms involved and the cellular processes affected. As a result, I characterized a novel mechanism of UPR-mediated transcriptional repression involving the translational regulation of the transcription factor C/EBPβ resulting in the suppression of the gene Il4ra, encoding an essential subunit of the IL-4/IL-13 receptor. As a consequence of this suppression, a novel effect of ER stress was identified in the impairment of IL-4/IL-13 signaling, a finding of potential significance in the study of inflammatory disease. In addition to this mechanism, I validated a novel approach to the identification of UPR-regulated transcription factors using publically available bioinformatic software. Through this analysis, I identified the transcription factor HNF4α as a novel post-translational UPR-regulated transcription factor, the regulation of which, resulted in the suppression of a number of lipid metabolic genes. This analysis not only identified a novel UPR-regulated transcription factor, but also presented a new tool for the characterization of UPR-mediated gene suppression. My work represents an independent and original investigation into the process of UPR-mediated gene suppression; and reveals that the UPR facilitates transcriptional suppression through the transcriptional, translational, and post-translational regulation of multiple transcription factors, resulting in the coordinated attenuation of physiological pathways. This function of the UPR is likely to contribute to metabolic, inflammatory, and other chronic disease states.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Saul-McBeth, Jessica. « Characterization of SipA, A Protein Important for Stress Responses in Vibrio cholerae ». University of Toledo Health Science Campus / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=mco1544540466901883.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

23

Lam, Dennis, et 林勁行. « A study of biological role of reactive oxygen species in cellular response in stress ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47869604.

Texte intégral

Résumé :

When proteins are unable to fold properly in the endoplasmic reticulum (ER), the resultant formation of misfolded proteins causes stress of the ER. Cells with ER stress often have a higher abundance of reactive oxygen species (ROS). Previous studies suggest that ROS could aggravate ER stress by further disrupting the ER protein folding process. More recent studies suggest that the unfolded protein response signaling pathways activated by ER stress could lead to the production of ROS. Such studies lead to the hypothesis that ER stress could be promoted by ROS, and vice versa. The aim of the present study is to test the above hypothesis by studying how ROS could be generated in ER-stressed cells. This is followed by investigating if ROS could increase or decrease the level of ER stress in cells. Finally, the extent of ER stress induced cell death in the presence and absence of ROS is assessed. The treatment of HeLa cells with tunicamycin (Tm), a common ER-stress inducing agent, resulted in the elevation of intracellular ROS that could be detected with the ROS-reactive probe dichlorodihydrofluorescein (DCF), but not dihydroethidium which is relatively specific towards superoxide anion. The Tm-induced elevation of ROS could be prevented by co-incubation of cells with thiol reductants such as dithiothreitol and N-acetylcysteine but not with the free radical scavenger ascorbate. The tunicamycin-induced elevation of ROS level could also be prevented by the over-expression of catalase in HeLa. These data is consistent with the idea that hydrogen peroxide is a major form of ROS produced in Tm-treated cells. In addition to elevation of ROS level, HeLa cells treated with tunicamycin also resulted in the phosphorylation of PERK and eIF2α, and the splicing of XBP-1. In the presence of cycloheximide to inhibit protein synthesis so as to deplete protein substrates for folding in the ER, tunicamycin-induced ER stress was greatly minimized as was evident by the absence of both the phosphorylation of PERK and splicing of XBP-1. However, the phosphorylation of eIF2α and elevation of DCF-detectable ROS remained unaffected. The cycloheximde-resistant phosphorylation of eIF2α could be prevented when cells were co-treated with thiol reductants, or upon the over-expression of catalase. These data suggest that the production of ROS in Tm-treated cells does not require the presence of ER stress as a prerequisite. Furthermore, the ROS so produced could induce phosphorylation of eIF2α without the need to cause ER stress in the first place. The quenching of ROS through the use of thiol reductants, or the over-expression of catalase, had no effect on inhibition of protein synthesis in cells treated with tunicamycin. However, the extent of cell death was significantly increased. The data obtained in this study is not consistent with the idea that ROS is a downstream product of ER stress, capable of inducing more ER-stress by a feedback mechanism. Therefore, a mutually enhancing effect between ER stress and ROS may not exist. The ROS found in stressed cells may serve to extend cellular survival under the condition of continuous stress.
published_or_final_version
Biochemistry
Doctoral
Doctor of Philosophy

Styles APA, Harvard, Vancouver, ISO, etc.

24

Li, Yimin. « Redox control of the transcriptional response to oxidative stress by Arabidopsis redox-sensitive basic leucine zipper protein 68 ». HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/324.

Texte intégral

Résumé :

Cellular redox states mediate various physiological and developmental processes. Mechanisms involved in sensing cellular redox state and linking it to an appropriate physiological response remains poorly understood in plants. Arabidopsis bZIP68 was previously found to undergo reversible oxidation in its Cys320 in cells under oxidative stress. In this study, it was found that bZIP68 was localized in the nucleus in Arabidopsis seedlings under normal conditions. Upon treatment of oxidative stress, bZIP68 underwent nucleocytoplasmic shuttling and accumulated in the cytoplasm. This stress-dependent nucleocytoplasmic shuttling depends on the redox-sensitive Cys320 and its nuclear export signal. bZIP68 suppresses expression of stress response genes under normal conditions and its loss-of-function mutation of bZIP68 leads to elevated expression of genes involved in oxidative stress defense including genes encoding for antioxidant proteins and for enzymes involved in biosynthesis of small molecule antioxidants. The bzip68 mutant also showed enhanced responses to stress treatment such as the oxidative stress and cold stress. Our study suggests that bZIP68 directly or indirectly senses perturbation of cellular redox states and links the redox change to activation of oxidative stress defense genes through redox regulation of transcription.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Liu, Jia, et 劉佳. « Role of FBXO31 in regulating MAPK-mediated genotoxic stress response and cancer cell survival ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/205657.

Texte intégral

Résumé :

Esophageal cancer is the third most common digestive tract malignancy. Along with surgery, genotoxic drugs (e.g. cisplatin) and radiotherapy are the mainstays of treatment for this disease. Environmental factors and environmental stress-induced responses contribute to esophageal tumorigenesis and chemoresistance. Studying key molecules in stress-induced signal pathway can help unravel the underlying mechanisms and discover rational therapeutic targets. Cyclin D1 is DNA damage response protein. Genotoxic stress induces rapid cyclin D1 degradation and the molecules mediating this response are cell-type dependent. The first part of this study investigated the changes of cyclin D1 expression in response to genotoxic stress in immortalized esophageal epithelial cells, which are experimental models commonly used to study the early events of cancer development. The results showed that cyclin D1 underwent rapid proteasomal degradation before p53-induced p21 accumulation, which substantiates that cyclin D1 plays a role in eliciting cell cycle arrest very early in the DNA damage response. FBXO31 and FBX4, two F-box proteins previously reported to mediate cyclin D1 degradation, were found to be accumulated and unchanged, respectively, after ionizing irradiation in immortalized esophageal epithelial cells and esophageal squamous cell carcinoma (ESCC) cell lines. Yet, knockdown of FBXO31 did not rescue rapid cyclin D1 degradation upon UV or ionizing irradiation. This led to the hypothesis that accumulation of FBXO31 may have novel functions beyond mediating cyclin D1 degradation in cells responding to genotoxic stress. The second part of this study explored the function of FBXO31 in genotoxic stress response. The accumulation of FBXO31 in cancer cells after exposure to various genotoxic stresses was found to coincide with p38 deactivation, giving the clue that FBXO31 may negatively regulate this important pathway. Further studies revealed that knockdown of FBXO31 resulted in sustained activation of stress-activated MAPKs (SAPKs) p38 and JNK, as well as increase in UV-induced cell apoptosis, whereas overexpression of FBXO31 had opposite effects. The inhibitory role of FBXO31 on SAPK activation and apoptosis was confirmed by shRNA rescue experiments. Consistent with the observed anti-apoptotic effect, soft agar, colony formation and in vivo xenograft experiments showed that FBXO31 had oncogenic function in ESCC. Moreover, in vitro and in vivo results showed that knockdown of FBXO31 could sensitize ESCC cells to cisplatin treatment. The mechanism underlying the inhibition of SAPKs by FBXO31 was investigated in the third part of this study. Co-immunoprecipitation results showed that FBXO31 could interact with MKK6 (a p38 activator), but not p38, JNK1, or other MAP2Ks. FBXO31 was found to be co-localized with MKK6 in the cytoplasm. Mapping of interaction domains of FBXO31 revealed that aa 115-240 and aa 351-475 were responsible for binding to MKK6. Further study found that binding of FBXO31 to MKK6 could facilitate the K48-linked polyubiquitination and degradation of MKK6. Taken together, the results of this study showed that FBXO31 accumulation upon genotoxic stress can promote the degradation of MKK6 via K48-linked ubiquitination, thereby inhibiting SAPK activation and protecting cancer cells from genotoxic stress-induced apoptosis. FBXO31 may be a potentially useful therapeutic target to overcome chemoresistance in cancer therapy.
published_or_final_version
Anatomy
Doctoral
Doctor of Philosophy

Styles APA, Harvard, Vancouver, ISO, etc.

26

Gammash, Mohammed Matuq. « Novel roles of the circadian clock protein neuronal PAS domain protein 2 (NPAS2) in the response to oxidative and heat stress ». Thesis, Bangor University, 2017. https://research.bangor.ac.uk/portal/en/theses/novel-roles-of-the-circadian-clock-protein-neuronal-pas-domain-protein-2-npas2-in-the-response-to-oxidative-andheat-stress(a5d513b0-84c5-486e-add9-afea7eeed9e2).html.

Texte intégral

Résumé :

Human NPAS2 is a basic-helix-loop-helix (BHLH) transcription factor with two N-terminal PAS domains that forms a hetero-dimeric complex with BMAL1/ARNTL to regulate the transcription of key circadian clock genes like Period and Cryptochrome. NPAS2 is unique in higher eukaryotic cells as both PAS domains contain one heme group each, which bind carbon monoxide. Although NPAS2 has been linked to cancer and neurological disorders, very little is known about its cellular roles. The results obtained in this study support a model in which NPAS2 responds to oxidative and heat stress in distinct manners. While oxidative stress results in the post-translational modification of NPAS2 and the formation of high molecular weight complexes, heat stress reduces the protein levels of NPAS2. These differences are also reflected in the changes to the NPAS2 mRNA levels. While oxidative stress increases expression of NPAS2, heat stress causes a drop in mRNA levels. The responses are cell line specific as, for example, the drop in NPAS2 protein levels after a heat shock was observed in MCF-7 breast cancer cells and HeLa cervical cancer cells, but not in non-malignant HEK-293 cells which may be of neuronal origin. Since both stress types are known to affect the peripheral clocks in human tissues in a manner which may be regulated by the MAP kinase p38β, it is proposed that NPAS2 is a novel target of this kinase. Why NPAS2 is regulated differently depending on the type of stress, could be linked with the different ways the p38 MAP kinase pathway responds to heat and oxidative stress. While heat activation is dependent on upstream kinases, heat activation may be dependent on the heat-induced increase in carbon monoxide in human cells. The works shows also that NPAS2 mRNA levels drop in the response to serum starvation and that the neuroblastoma KELLY cell line does not, or only at a very reduced level, express NPAS2 although an analysis of a large panel of human tissues shows high NPAS2 expression in the brain. A bioinformatical analysis of missense single nucleotide polymorphisms (SNPs) located the N-terminal domain of NPAS2 identifies two SNPs (S204P, rs750277651 and T252N, rs555063320) which may affect a p38 (S202) and EYRK1A (T252) kinase modification site, respectively. This is of interest as p38β may regulate NPAS2 and the dual-specific DYRK1A kinase is known to regulate the protein turnover of Cryptochrome. In summary, the work makes a strong case for NPAS2 as a novel target of the p38β MAP kinase pathway in the cellular response to oxidative and heat stress.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Geary, Bethany. « Determining the rates of protein synthesis in the zebrafish heart in response to chronic unpredictable stress ». Thesis, University of the Highlands and Islands, 2016. https://pure.uhi.ac.uk/portal/en/studentthesis/determining-the-rates-of-protein-synthesis-in-the-zebrafish-heart-in-response-to-chronic-unpredictable-stress(0b49f21e-543c-4ba9-a24d-496ade328b0b).html.

Texte intégral

Résumé :

The proteome is in constant flux and therefore it is important to understand the contribution of protein dynamics to the function of an organism. The zebrafish (Danio rerio) is a recognised model organism that is widely used to investigate physiological processes. The focus of this thesis was to develop a method to calculate the rates of synthesis of heart proteins of zebrafish on a proteome-wide scale. The initial stage of the project involved the optimisation of a method to characterise the protein complement of individual zebrafish hearts. It was concluded that for the rapid screening of proteins 1-dimensional gel electrophoresis in conjunction with high resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) was the most appropriate experimental approach. In order to determine the rates of protein synthesis, zebrafish were administered with a stable isotope-labelled amino acid ([2H7] L-leucine) via the diet and its incorporation into heart proteins was monitored over an 8 week time course. Using this method it was possible to calculate the synthesis rates of over 600 proteins. The experimental strategy was then applied to define the changes in protein synthesis rates in hearts from zebrafish that were subjected to chronic unpredictable stress (CUS). A variety of stressors on zebrafish comprising air emersion, net chasing or net confinement were employed to model CUS. These approaches were validated by a parallel behavioural analysis. The results revealed that glycolytic and gluconeogenic enzymes as well as proteins involved in hypoxia had significantly altered synthesis rates in response to induced stress. This thesis describes for the first time a proteomics approach to determine the rates of synthesis of individual proteins in the zebrafish and its application to investigate the effects of stress conditions on heart proteome dynamics.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Omikorede, Omotola. « The role of ER stress and the unfolded protein response in obesity associated type 2 diabetes ». Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10182.

Texte intégral

Résumé :

Pancreatic β-cell dysfunction plays a central role in the pathogenesis of type 2 diabetes. This dysfunction is characterised by secretory defects in the β-cells and the loss of β-cell mass, at least in part secondary to increased β-cell apoptosis. Although the mechanisms through which β-cell dysfunction develops are unclear, accumulating evidence suggests that elevated levels of circulating free fatty acids (FFAs) as can occur under conditions of obesity, play a role in the pathogenesis of type 2 diabetes. It has been suggested that endoplasmic reticulum (ER) stress and the resulting unfolded protein response (UPR) play a role in FFA induced β-cell dysfunction. This thesis was aimed at investigating the role of obesity induced ER stress in the development of β-cell dysfunction in type 2 diabetes. The UPR was induced in MIN6 β-cells in response to both the saturated fatty acid (FA) palmitate, and unsaturated fatty acid oleate. Palmitate however induced a more marked ER stress response in comparison to oleate. Although both FAs induced ER stress, only palmitate evoked apoptosis in the β-cells, indicative of the differential signalling by unsaturated and saturated fatty acids. ER stress and evidence of functional adaptation was also observed in islets obtained from Zucker and Zucker diabetic fatty (ZDF) rodent models of obesity. The development of β-cell dysfunction in the progression from obesity to obesity associated type 2 diabetes in the ZDF rats was however not accompanied by a further increase in ER stress markers. This suggests that ER stress signalling does not play a significant role in the development of β-cell dysfunction. In conclusion, the studies outlined in this thesis demonstrate that ER stress is induced in in vitro and in vivo models of β-cell lipotoxicity. It is however apparent, that ER stress does not contribute significantly to β-cell dysfunction and perhaps, only plays a small insignificant role in β-cell apoptosis in the pathogenesis of type 2 diabetes. It is hypothesised, that β-cell dysfunction develops in type 2 diabetes as a result of the inability of the β-cell to mount an additive UPR in response to ER stress.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Kershaw, Rachael Maria. « Delayed response of the CYS326 variant of the DNA repair protein OGG1 to cellular oxidative stress ». Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/3035/.

Texte intégral

Résumé :

Reactive oxygen species (ROS) are generated via endogenous and exogenous sources. ROS are involved in essential cellular processes but when present in excess, can overwhelm antioxidant defences and induce a range of damaging DNA lesions. The most commonly oxidised DNA base is guanine. This generates products including 7,8-dihydro-8-oxodeoxyguanine (8-oxo dG) which can result in G:C->T:A transversion mutations, frequently found in human cancers. Oxidative damage is also implicated in normal cellular ageing and degenerative diseases. 8-oxo dG repair is initiated by the base excision repair enzyme 8-oxoguanine DNA glycosylase 1 (OGG1). Modulation of OGG1 activity in oxidising conditions has implications for mutation prevention. This thesis investigates regulation of OGG1 under oxidising conditions using BSO, which increases intracellular ROS. Chapter 3 shows that following BSO treatment, mouse OGG1 activity in mouse embryonic fibroblast (MEF) cells increases with no change in mRNA levels, whereas identical treatment has no effect on rat OGG1 activity in MH1C1 cells but modulates protein levels. A human OGG1 (hOGG1) variant with serine exchanged for cysteine at codon 326 (Cys326-hOGG1) is associated with reduced repair ability under oxidising conditions. Chapter 4 describes the development of mOGG1-/- MEF cells stably expressing Ser326- or Cys326-hOGG1 and in chapter 5 these cells are used to investigate Ser326- and Cys326-hOGG1 activity, gene expression, protein localisation, homo-dimer formation and retention within an insoluble nuclear fraction following BSO treatment. Data presented shows that the activity of both Ser326- and Cys326-hOGG1 increase following BSO treatment but Ser326-hOGG1 peak activity occurs 12 hours prior to that of Cys326-hOGG1. This increased activity is not associated with increased gene expression or protein, or any protein localisation change; however, Cys326-hOGG1 is retained to a lesser extent in an insoluble nuclear fraction following BSO treatment. The findings presented in this thesis show that OGG1 activity is modulated post-transcriptionally in response to increased ROS and provide a possible mechanism behind impaired Cys326-hOGG1 repair in oxidising conditions, further supporting the role of Cys326-hOGG1 in the process of carcinogenesis.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Davies, Matthew. « Investigation of the unfolded protein response and other stress-related responses in distinct models of neurodegeneration ». Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/390653/.

Texte intégral

Résumé :

There is no cure for chronic neurodegenerative diseases and disease-modifying therapies are limited. In order to develop successful disease-modifying therapies the molecules and pathways that underpin early stages of disease, such as synapse loss, need to be better defined. Three distinct in vivo mouse models of neurodegeneration have been used to investigate molecular stress response molecules and pathways. These models are the ME7 prion model, the cysteine string protein alpha (CSP?) -/- model and a kainic acid model of excitotoxicity. In all cases hippocampal tissue from mice was used to investigate the neuropathology and associated stress-related pathways. The unfolded protein response (UPR) and other stress-related response molecules: immediate early genes (ATF3, c-Jun and c-Fos), activity-induced immediate early genes (Arc and Homer1a) and a cellular physiological and environmental damage stress sensor (GADD45?) were investigated. Biochemical and immunohistochemistry analysis revealed no evidence for a robust and classic UPR in any of the three models despite neuropathological changes associated with these distinct insults being evident. However, other stress-related response molecules were induced in these models and the induction of some of these occurred at the same time/prior to synapse loss suggesting that these are early responses and potential therapeutic targets for modifying neurodegenerative disease. Tissue analysis is confounded by cellular heterogeneity. To investigate discrete cell specific events laser capture microdissection (LCM) was used to isolate the cell bodies of dysfunctional CA3 pyramidal neurons across key stages of ME7 prion disease. Optimisation of LCM enabled enrichment of CA3 pyramidal neurons and targeted analysis of UPR molecules. mRNA analysis failed to show strong evidence for a robust induction of the UPR in these vulnerable CA3 pyramidal neurons. Total RNA has also been used for RNA sequencing to analyse differentially expressed genes and molecular pathways activated during prion disease progression. The aim of this targeted approach will be to resolve molecular targets and pathways which might mitigate the progression of chronic neurodegenerative diseases.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Karreman, Robert Jan. « The localization, function and applications of the stress response protein Hsp12p in the yeast Saccharomyces cerevisiae ». Doctoral thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4278.

Texte intégral

Résumé :

Word processed copy.
Includes bibliographical references (leaves 117-132).
Since 1990, the yeast Saccharomyces cerevisiae small heat shock protein Hsp12p, has continuously appeared in data associated with stress responses in this organism. Hsp12p is expressed abundantly in response to a large variety of different stresses, but for many years has eluded researchers as to its function, primarily because the viability of yeast strains lacking HSP12 are unaffected by osmotic stress and heat shock. Subsequent studies indicated that Hsp12p played a role in the adaptation of the cell wall of Saccharomyces cerevisiae to conditions of stress. However, the exact in vivo localization, specific function and mediation of function of Hsp12p had yet to be elucidated. The localization of Hsp12p was determined by fusion to the green fluorescent reporter protein, Gfp2p and a combination of epifluorescent microscopy and confocal imagery. Chemical extraction revealed that Hsp12p was present in the cell wall while fluorescent imagery was not conclusive. This fluorescent Hsp12p construct was later employed in a novel application to sense the stress status of yeast, which bears future promise for use in an industrial setting.

Styles APA, Harvard, Vancouver, ISO, etc.

32

Dyer, Scott Douglas. « Evaluation of the efficacy of the stress protein response as a biochemical water quality biomonitoring method ». Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc798352/.

Texte intégral

Résumé :

The stress protein response (SPR) is a conserved and ubiquitous mechanism that enables cells to tolerate a wide variety of environmental insults. This response involves the preferential synthesis of an array of proteins with different molecular weights. These proteins perform a variety of functions, such as protein folding, multimeric protein assembly, steroid receptor binding, and heme catabolism. To evaluate the potential use of the SPR as a biomonitoring tool, a stepwise plan was utilized that proceeded through various physical and chemical laboratory exposures and culminated with a field validation study. The goals of the laboratory exposures were threefold: (1) determine the time required for induction of the SPR; (2) determine the dose-responsiveness of the SPR; and (3) compare the increased syntheses and accumulations of stress proteins to classical toxicological endpoints (i.e. percent mortality, LC50, LC1, etc).

Styles APA, Harvard, Vancouver, ISO, etc.

33

Chew, Yee Lian. « Protein with Tau-like repeats (PTL-1) modulates the oxidative stress response, neuronal ageing and lifespan ». Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12497.

Texte intégral

Résumé :

Protein with Tau-like repeats (PTL-1) is the sole Tau /MAP2/MAP4 homolog in Caenorhabditis elegans. Dysregulation of Tau is a pathological hallmark of neurodegenerative diseases such as Alzheimer’s disease. Therefore, reducing Tau levels has been suggested as a therapeutic strategy. We used PTL-1 to model the biological functions of a Tau-like protein without the complication of functional redundancy. Firstly, our data indicate that PTL-1 in the nervous system mediates the oxidative stress response in a pathway that may involve the C. elegans homolog of the Nrf2 transcription factor, SKN-1. In addition, we found that ptl-1 mutant animals are short-lived, and that lifespan modulation by PTL-1 may occur via similar processes to those mediated by SKN-1. We also observed that the short-lived phenotype of ptl-1 mutants can be rescued by transgenic re-expression of PTL-1 but not human Tau. Secondly, we show that PTL-1 maintains the structural integrity of neurons with increasing age. This phenotype observed in ptl-1 mutant animals could again be rescued by PTL-1 re-expression but not by human Tau. Thirdly, our data also indicate that the regulation of neuronal ageing by PTL-1 is cell-autonomous. We expressed PTL-1 in touch neurons and showed rescue of the neuronal ageing phenotype of ptl-1 mutant animals in these neurons but not in another neuronal subset. Knockdown of PTL-1 specifically in touch neurons also resulted in premature neuronal ageing in these neurons but not in a distinct subset of neurons, further supporting the conclusion that PTL-1 functions in a cell-autonomous manner. Interestingly, we showed that expression of PTL-1 in touch neurons alone was unable to rescue the shortened lifespan observed in null mutants, indicating that premature neuronal ageing in touch neurons and organismal ageing can be decoupled. Our data show that PTL-1 in C. elegans is a useful model to investigate the physiological functions of a Tau-like protein. Overall, our findings that PTL-1 is involved in the stress response, neuronal ageing and lifespan modulation suggest that some of the effects of Tau pathology may result from the loss of physiological Tau functions and not solely from a toxic gain-of-function due to an accumulation of Tau.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Scuto, Maria Concetta. « Mitochondrial biogenesis, protein misfolding and cellular stress response in aging and in neurodegenerative disorders : proteomic approach ». Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/4055.

Texte intégral

Résumé :

Il genoma mitocondriale gioca un ruolo chiave nell¡¯invecchiamento e nei disordini neurodegenerativi. La disfunzione mitocondriale ¨¨ infatti caratteristica di diversi disordini, ed il danneggiamento mitocondriale determinerebbe un¡¯alterata attivit¨¤ della catena respiratoria come riscontrato nel morbo di Parkinson, nella malattia di Alzheimer e nella malattia di Huntington. Tali disfunzioni nell¡¯attivit¨¤ del complesso respiratorio, possibilmente associati con le alterazioni del bilancio ossidante/antiossidante, si pensa siano alla base dei difetti del metabolismo energetico ed inducano la degenerazione cellulare. Uno dei principali sistemi redox intracellulari coinvolti nella neuroprotezione ¨¨ il sistema dei vitageni che potrebbe essere un potenziale target per un nuovo intervento citoprotettivo. I vitageni codificano per le proteine citoprotettive: heat shock protein Hsp-70 ed heme ossigenasi-1 HO-1, come anche per la tioredoxina reduttasi e le sirtuine. Bis(2-hydroxybenzylidene)acetone ¨¨ un potente induttore della risposta della fase 2 attraverso la via dell¡¯ Keapl-Nrf2-ARE, per studiare gli effetti protettivi di molecole ad attivit¨¤ antiossidante, tra cui l¡¯HBB-2. E¡¯ stato ipotizzato il ruolo di un composto antiossidante di sintesi come il bis(2-hydroxy-benzilidene) acetone o HBB-2, quale modulatore dei vitageni per un possibile suo impiego in vivo ed ¨¨ stato ipotizzato anche un suo effetto neuroprotettivo in cellule umane di neuroblastoma di tipo SH-SY5Y esposte a stress nitrosativo indotto dal SIN-1, per sostenere l¡¯ipotesi che l¡¯HBB potrebbe avere effetti anti-aging nel Sistema Nervoso centrale (SNC). La nefropatia diabetica (DN) ¨¨ una delle pi¨´ gravi complicanze del diabete di tipo 1 e tipo 2 ed ¨¨ la principale causa di dialisi nel mondo occidentale. La predisposizione alla nefropatia diabetica (DN) ¨¨ fortemente associata con un polimorfismo nel gene CNDP1, che codifica per la proteina carnosinasi del siero (CN1). CN1 ¨¨ un dipeptidasi che catalizza l'idrolisi del dipeptidi carnosina, anserina e omocarnosina. E¡¯ stato ipotizzato il metabolismo della carnosinasi renale nei topi db / db. L¡¯attivit¨¤ renale di CN1 aumenta con l'et¨¤ ed era significativamente pi¨´ alta nei topi diabetici rispetto ai controlli. Il trattamento con carnosina impedisce le alterazioni del metabolismo della carnosina renale. Depositi di amiloide, costituiti da aggregati di ¦Â-amiloide, sono una caratteristica di molte malattie neurodegenerative, come, l¡¯ Alzheimer, il decadimento cognitivo lieve e il morbo di Parkinson. Inoltre sono stati recentemente implicati nella patogenesi del danno retinico, cos¨¬ come le malattie di degenerazione maculare e glaucoma et¨¤-correlate. Il glaucoma ¨¨ una neuropatia ottica progressiva caratterizzata da degenerazione del tessuto neuronale dovuto alla perdita di cellule gangliari della retina (RGCs), con compromissione del campo visivo nel tempo. Diverse investigazioni sperimentali dimostrano dimostrano un legame tra AD e glaucoma. Di conseguenza, i farmaci designati a target ¦Â-amiloide sono stati scoperti ridurre la degenerazione apoptotica di RGCs, osservata in vitro e in vivo. Inoltre, la presenza di livelli aumentati di ¦Â-amiloide caratterizza il glaucoma come una malattia misfolding e suggerisce anche un ruolo per lo stress ossidativo nella patogenesi del danno retinico degenerativo associato al glaucoma. Il presente studio elucida sulla risposta allo stress cellulare nelle cellule periferiche in pazienti con glaucoma rispetto ai volontari sani, al fine di ottenere informazioni sui meccanismi patogenetici che operano nel danno neurodegenerativo associato a questa malattia e sfruttare il possibile ruolo dei vitageni per nuovi targets terapeutici e per limitare il danno ossidativo associato alla degenerazione che si verifica nel glaucoma.

Styles APA, Harvard, Vancouver, ISO, etc.

35

Puddu, F. « Functional Analysis of the Cell Cycle Protein Dpb11 in Response to DNA Damage and Replicative Stress ». Doctoral thesis, Università degli Studi di Milano, 2009. http://hdl.handle.net/2434/158404.

Texte intégral

Résumé :

DNA molecule is complex, fragile and can suffer different damages. Specific DNA repair mechanisms were evolved to respond to these challenges, and to allow a faithful transmission of genetic information throughout generations. If the damaging conditions are extensive, a mechanism called DNA damage checkpoint takes care of arresting the progression of the cell division cycle to allow the cell to repair the damage before proceeding further. Genes involved in the DNA damage checkpoint are conserved throughout evolution and mutations in the human genes are known to produce severe illnesses - like Ataxia Telangiectasia - and genomic instability, which is usually considered as the onset of cancer: indeed checkpoint genes, like BRCA1, were found to be mutated in different types of cancers. The yeast Saccharomyces cerevisiae has been widely used to study the DNA damage checkpoint because, despite its evolutionary distance, the easiness in generating knockout and mutant strains has facilitated the understanding of the underlying mechanisms. In this yeast, as in humans, the signal that activates the checkpoint is represented by the ssDNA covered by RPA, to which many different checkpoint and repair factors are recruited. ssDNA signals are responsible for the activation of Mec1 (hATR), the apical kinase of the checkpoint pathway, but in humans two other factors are required for this signalling to occur: a ring-like heterotrimer - the PCNA-like complex - which is loaded onto DNA in response to damage and which recruits the second factor, TopBP1. Once active, Mec1 kinase phosphorylates a series of substrates, among which there is the Ddc1 subunit of the PCNA-like complex, and the Rad9 protein; phosphorylated Rad9 allows the recruitment of Rad53, the central kinase of the checkpoint whose Mec1-dependent activation contributes to cell survival after DNA damage and replication stress. To be phosphorylated by DNA-bound Mec1, the Rad9 protein must be recruited to chromatin: this process involves the binding of a Rad9 domain - the Tudor domain - to a methylated lysine on histone H3. Indeed, cells mutated in the conserved H3 lysine, in the Tudor domain or in the histone methyltransferase Dot1 are defective in Rad9 and Rad53 phosphorylation when DNA is damaged in the G1 phase of the cell cycle. Surprisingly, when these mutants receive a DNA damage in mitosis, they are still able to phosphorylate Rad9 and Rad53, suggesting the presence of a second pathway that, in M phase, provides an alternative way for Rad9 to be phosphorylated. In this thesis evidences regarding this alternative pathway for Rad9 recruitment and phosphorylation are provided. This pathway depends upon the C-terminal tail of Dpb11, the yeast homologue of human TopBP1, and on the Mec1-dependent phosphorylation of threonine 602 of the Ddc1 subunit of the PCNA-like complex. We show that Dpb11 itself is phosphorylated after DNA damage and that this phosphorylation is reduced in the presence of a non-phosphorylatable 602-residue on Ddc1, suggesting that in these conditions Dpb11 cannot be functionally recruited. Supporting this idea the two-hybrid interaction between Ddc1 and Dpb11 requires the presence of a functional Mec1 kinase. Although being capable of in vitro stimulation of Mec1 kinase activity, after UV irradiation in M phase, Dpb11 is not required for Mec1 to phosphorylate its binding partner Ddc2. On the other hand, we provide evidences that Dpb11 performs its Mec1 activation task during the response to global replication stress; indeed Dpb11 and the PCNA-like complex are independently required to obtain a proper phosphorylation of histone H2A - here used as a marker of Mec1 kinase activity - and a full Rad53 activation. Consistent with this observation ddc1Δdpb11-1 mutants are extremely sensitive to chronic exposition to hydroxyurea, a commonly used chemotherapeutic drug that generates replication stress by reducing the concentration of dNTPs in the cell. We also provide evidence that this lethality is not due to classical checkpoint functions like the stabilisation of stalled replication forks or the ability to delay entrance in M phase. We suggest also that other proteins known to be involved in checkpoint activation after hydroxyurea treatment are working in the pathway in which Dpb11 is involved.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Tan, Shixiong Biotechnology &amp Biomolecular Sciences Faculty of Science UNSW. « Cellular mechanisms affecting redox homeostasis in response to stress in Saccharomyces cerevisiae ». Awarded by:University of New South Wales. Biotechnology & ; Biomolecular Sciences, 2009. http://handle.unsw.edu.au/1959.4/44627.

Texte intégral

Résumé :

Maintainence of appropriate redox homeostasis is crucial for processes such as protein folding in the endoplasmic reticulum (ER) and to minimise genesis of oxidative stress. Previous studies have indicated a possible link between ER stress and production of reactive oxygen species (ROS) although the cellular mechanisms involved were not fully elucidated. To investigate the cellular mechanisms involved in tolerance to oxidative stress and ER stress, genome-wide screens were performed to identify mutants sensitive to chronic ER stress induced by dithiothreitol and tunicamycin. These screens identified the Cu,Zn superoxide dismutase (SOD1) and genes involved in NADPH generation (RPE1, TKL1) as important for chronic ER stress tolerance. Superoxide anion has been identified as one of the ROS generated during ER stress. The ER oxidoreductase Ero1p, previously implicated in ROS production in vitro, did not appear to be a source of superoxide when the protein was over-expressed. It was also found that cellular NADP(H) levels affected induction of the unfolded protein response (UPR), since cells lacking TKL1 or RPE1 exhibited decreased UPR induction. These data indicate an important role for superoxide dismutase and cellular NADP(H) in survival of cells during ER stress. Subsequent analysis determined that NADPH generation was also required for adaptation to H2O2. Mutants affected in NADPH production were chronically sensitive to H2O2 but resistant to an acute dose. These mutants over-accumulated reduced glutathione (GSH) but maintained normal cellular redox homeostasis. This over- production of GSH was not regulated at the transcriptional level of GSH1 encoding ??- glutamyl cysteine synthetase. These data raise the important question as to how cells maintain cellular glutathione redox balance. To better understand how cells respond to perturbations in glutathione redox homeostasis, cells deleted for GLR1, encoding GSSG reductase, were exposed to extracellular oxidised glutathione (GSSG) and intracellular GSH and GSSG were monitored over time. Intriguingly cells lacking GLR1 showed increased levels of GSH accumulation upon GSSG treatment in a manner independent of GSH synthesis. It was subsequently found that the cytosolic thioredoxin-thioredoxin reductase system contributes to the reduction of GSSG in vivo.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Budi, Bunarta Hendra (Akin), et akin budi@rmit edu au. « On the effects of external stresses on protein conformation ». RMIT University. School of Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20061116.123431.

Texte intégral

Résumé :

The use of electromagnetic devices such as microwave ovens and mobile phones has certainly brought convenience to our lives. At the same time, the proliferation of said devices has increased public awareness of the potential health hazards. It is generally assumed that there is little or no risk associated with the use of electromagnetic devices, based on the small amount of power associated with those devices. However, case studies on animals indicate that the risk cannot be entirely ruled out. It has long been known that proteins are sensitive to stress, arising from various sources such as temperature, chemical, pressure, and changes in pH condition. In all of these cases, the protein exhibits clear signs of damage and distress, which range from slight unfolding to complete loss of structure. Frequently, the damage to the protein is alleviated by refolding, either by itself or by the aid of molecular chaperones. However, if the damage to the protein is too great, the protein will generally undergo proteolysis. Opinion has been divided over the implication of prolonged use of electromagnetic devices to human health. Studies conducted on animals so far have given conflicting results. The studies on the separate components, electric and magnetic fields, also give inconclusive results. This indicates that our understanding on how electric and magnetic fields interact with biological matter is incomplete. In this project, we use molecular dynamics to explore the behaviour of two forms of insulin chain-B, isolated and monomeric (in the presence of chain-A with all disulfide bonds intact), at ambient conditions and under the influence of various stress. Specifically, we focus our attention to thermal stress and electric field stress. The electric field stress considered in this study takes several forms: static and oscillating with three different frequencies. These fields have strength ranging from 1806 V/m to 109 V/m. By performing molecular dynamics simulations totalling over 500 ns, we have gained valuable insights into the effects of elevated temperature and electric field on insulin chain-B. We observed differences in the damage mechanisms by the application of static electric field and oscillating field. The application of static fields restricts the conformational freedom of a protein, whereas the application of oscillating fields increases the mobility and flexibility of the protein, similar to the effect of thermal stress. Both of these interfere with the normal behaviour of a protein. We have also observed frequency-dependent effects, with low frequency fields having static field-like characteristics in damage mechanism.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Gross, Rosalyn. « Relationship of anger trait and anger expression to c-reactive protein in post-menopausal women ». [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002644.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

39

Bouvier, Nicolas. « Conséquences rénales de l’activation de la réponse UPR (Unfolded protein response) par des stress toxique et ischémique ». Thesis, Paris 5, 2012. http://www.theses.fr/2012PA05P626/document.

Texte intégral

Résumé :

Le rein natif et le greffon rénal peuvent être soumis à de multiples agressions conduisant à la détérioration progressive du parenchyme. Ces agressions peuvent être spécifiques (stress toxique, immunologique) et/ou non spécifiques (stress ischémique) et vont engendrer des réponses pouvant entraîner à la fois une diminution de la consommation d’énergie, une augmentation des apports afin de maintenir l’homéostasie tissulaire et la survie mais aussi une réaction inflammatoire et l’apoptose pouvant conduire à la fibrose. Parmi celles-ci, on peut nommer les voies HIF1α, mTOR, le stress du réticulum endoplasmique (RE), l’autophagie, l’activation de l’immunité innée et acquise. La réponse adaptative qui suit le stress du RE, la réponse UPR (Unfolded protein response), est une voie adaptative dont les implications sont actuellement encore peu connues dans le domaine de la pathologie rénale. Celle-ci se compose de trois effecteurs principaux : Perk, Ire1 et ATF6. A l’aide de deux modèles de stress toxique (ciclosporine) et ischémique (carence en glucose) sur deux modèles cellulaires distincts (cellulaires endothéliales artérielles et cellules tubulaires rénales), et dans des modèles in vivo, nous avons montré que le stress du RE était impliqué à la fois dans l’apparition de modifications phénotypiques endothéliales évocatrices de transition endothélio-mésenchymateuse induites par la ciclosporine et à la fois dans l’induction de réponses inflammatoire (régulation de NF-κB par Ire1) et angiogénique (régulation distincte de VEGF, bFGF et angiogénine par Perk et Ire1) induites par la carence en glucose. La réponse UPR semble modulée de façon subtile au cours de ces stress car les trois effecteurs n’engendrent pas des réponses identiques. Ces travaux apportent ainsi une meilleure compréhension des mécanismes d’adaptation au cours de stress variés, montrent que le stress du RE est impliqué dans ces réponses adaptatives et que la réponse peut être différente selon les effecteurs de la réponse UPR. Cette meilleure compréhension pourra permettre de valider des biomarqueurs précoces et des modulateurs de la réponse UPR afin de prévenir la dégradation du parenchyme rénal
Native and grafted kidneys are stressed by multiple specific or non-specific insults leading to progressive structural deterioration. Responses to these insults are adaptive and preserve cell survival but may also promote inflammation, fibrosis and apoptosis. The most important of these adaptive pathways are HIF1α pathway, mTOR pathway, autophagy, unfolded protein response (UPR). The consequences of the UPR in kidney injuries are not well known. The objective of this study is to delineate the mechanisms and consequences of the activation of the UPR in response to toxic (cyclosporine) and ischemic (glucose starvation) stresses in two distinct cellular models (arterial endothelial cells and renal tubular cells). Here, we showed that UPR was engaged in cyclosporine-induced endothelial phenotypic changes, glucose starvation-induced inflammatory and angiogenic responses: NF-κB regulation by Ire1; distinct VEGF, bFGF and angiogenin regulation by Perk and Ire1. UPR is subtly modulated since its transducers do not induce identical processes. In conclusion these comprehensive works, we demonstrate the UPR is implicated in stress-induced adaptive pathways with different downstream responses according to the effector. Renal tissue degradation could be prevented by discovering and validating early biomarker and UPR modulators

Styles APA, Harvard, Vancouver, ISO, etc.

40

Bouvier, Nicolas. « Conséquences rénales de l'activation de la réponse UPR (Unfolded protein response) par des stress toxique et ischémique ». Phd thesis, Université René Descartes - Paris V, 2012. http://tel.archives-ouvertes.fr/tel-00793364.

Texte intégral

Résumé :

Le rein natif et le greffon rénal peuvent être soumis à de multiples agressions conduisant à la détérioration progressive du parenchyme. Ces agressions peuvent être spécifiques (stress toxique, immunologique) et/ou non spécifiques (stress ischémique) et vont engendrer des réponses pouvant entraîner à la fois une diminution de la consommation d'énergie, une augmentation des apports afin de maintenir l'homéostasie tissulaire et la survie mais aussi une réaction inflammatoire et l'apoptose pouvant conduire à la fibrose. Parmi celles-ci, on peut nommer les voies HIF1α, mTOR, le stress du réticulum endoplasmique (RE), l'autophagie, l'activation de l'immunité innée et acquise. La réponse adaptative qui suit le stress du RE, la réponse UPR (Unfolded protein response), est une voie adaptative dont les implications sont actuellement encore peu connues dans le domaine de la pathologie rénale. Celle-ci se compose de trois effecteurs principaux : Perk, Ire1 et ATF6. A l'aide de deux modèles de stress toxique (ciclosporine) et ischémique (carence en glucose) sur deux modèles cellulaires distincts (cellulaires endothéliales artérielles et cellules tubulaires rénales), et dans des modèles in vivo, nous avons montré que le stress du RE était impliqué à la fois dans l'apparition de modifications phénotypiques endothéliales évocatrices de transition endothélio-mésenchymateuse induites par la ciclosporine et à la fois dans l'induction de réponses inflammatoire (régulation de NF-κB par Ire1) et angiogénique (régulation distincte de VEGF, bFGF et angiogénine par Perk et Ire1) induites par la carence en glucose. La réponse UPR semble modulée de façon subtile au cours de ces stress car les trois effecteurs n'engendrent pas des réponses identiques. Ces travaux apportent ainsi une meilleure compréhension des mécanismes d'adaptation au cours de stress variés, montrent que le stress du RE est impliqué dans ces réponses adaptatives et que la réponse peut être différente selon les effecteurs de la réponse UPR. Cette meilleure compréhension pourra permettre de valider des biomarqueurs précoces et des modulateurs de la réponse UPR afin de prévenir la dégradation du parenchyme rénal.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Isa, Suleiman. « The impact of natural and synthetic PPARγ ligands on endoplasmic reticulum stress and the unfolded protein response ». Thesis, Cardiff Metropolitan University, 2012. http://hdl.handle.net/10369/3294.

Texte intégral

Résumé :

Peroxisome Proliferator-Activated Receptor-y (PPARy) is a ligand-activated nuclear hormone receptor. PPARy is activated by naturally-occurring (eg. oxidized low-density lipoprotein (oxLDL), and 15-deoxy-delta-12,14-prostaglandinJ2 (15dPGJ2)) and pharmacological compounds (eg. the anti-hyperglycemic agent Rosiglitazone). However, disturbance of ER functions by PPARy ligands causes ER stress, and activation of the unfolded protein response (UPR). In the current study, the impacts of natural and synthetic PPARy ligands on ER stress/UPR were investigated. Treatment (0.5h) of HL-1 cardiomyocytes or MM6 monocytes with Rosiglitazone (0- 10µM)/15dPGJ2 (0-3µM) disrupted ER homeostasis via inhibition of the ER 'housekeeping Ca2+ pump' SERCA2b. Inhibition of SERCA2b-catalysed Ca2+ pumping activity led within 4h to unchecked Ca2+ leakage from the ER, and activation of UPR transcription factor XBP-1. Within 24-72h, this caused up-regulation of UPR genes, Bip and SERCA2b. However, severe ER stress impairs the ability of BiP/SERCA2b to restore ER homeostasis; hence, UPR can lead to apoptosis via activation of proapoptotic CHOP/caspase pathways. Interestingly, this was seen at lower Rosiglitazone levels in HL-l than in MM6 cells. Thus, Rosiglitazone and 15dPGJ2 can cause apoptosis, particularly in HL-1 cells, via a mechanism involving ER stress/UPR. oxLDL intenalization by monocyte/macrophages leads to incorporation of cholesterol molecules into the ER membrane, SERCA2b inhibition, unchecked Ca2+ leakage from the ER, ER stress and UPR activation. Different monocyte/macrophage subsets were investigated: with regard to activation of XBP-I; upregulation of UPR target genes (BiP/CHOP); and apoptosis/cell viability, the effects of oxLDL (1-40µg/ml; 24h) exhibited a consistent pattern: non-polarised monocyte/macrophages were less sensitive to oxLDL than M2-polarised macrophages. Such enhanced susceptibility of anti-inflammatory M2-macrophages could, over time, result in a shift similar to that seen in obese individuals in vivo; i.e. relative increases in proportion of non-M2 cells within each macrophage population, and thus contribute to the development of a proinflammatory milieu in the tissues of obese individuals.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Do, Minh-Ha T. « Stress, mixed messages, and hormone signaling regulation of translation and the unfolded protein response in pituitary gonadotropes / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3307121.

Texte intégral

Résumé :

Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed July 1, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 166-176).

Styles APA, Harvard, Vancouver, ISO, etc.

43

Diedrichs, Danilo Roberto. « A mathematical model of the unfolded protein response to stress in the endoplasmic reticulum of mammalian cells ». Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3284.

Texte intégral

Résumé :

The unfolded protein response (UPR) is a cellular mechanism whose primary functions are to sense perturbations in the protein-folding capacity of the endoplasmic reticulum and to take corrective steps to restore homeostasis. Although the UPR is conserved across all eukaryotic cells, it is considerably more complex in mammalian cells, due to the presence of three interconnected pathways triggered by separate sensor proteins, a translation attenuation mechanism, and a negative feedback loop. The mechanisms of these interacting biochemical pathways in the mammalian UPR allow for a better fine-tuning of the response than in the case of lower eukaryotes, such as yeasts. The present thesis develops a quantitative mathematical model for the dynamics of the UPR in mammalian cells, which incorporates all the proteins and interactions between them that are known to play a role in this response. This model can be used to provide quantitative information about the levels of its components throughout the response, and to analyze the ramifications of perturbations of the UPR. The model uses a system of ordinary nonlinear differential equations based on biochemical rate equations to describe the dynamics of the UPR as a network of interacting proteins and mRNAs. An early model is presented as a first attempt to investigate the UPR network and construct an inclusive wiring diagram, as well as suggesting a framework to model the differential equations. Then, a refined, quantitative model is designed based on experimental data collected on Mouse Embryonic Fibroblasts treated with Thapsigargin to induce stress and trigger the UPR. The model defines the differential equations and determines the unknown kinetic parameters by optimizing the fit of the system's solution to the experimental data. It includes the UPR's intrinsic feedback loops and allows for the integration of various forms of external stress signals. To the best of our knowledge, it is the first, data-validated, quantitative model in the literature for the UPR in mammalian cells. The last chapters of the thesis address, from a modeling point of view, two important questions for the UPR: (1) cell survival versus apoptosis; and (2) incompleteness of the biological wiring diagram. Recent experimental results show that the UPR is capable of producing qualitatively different results leading to cell survival or death depending on the nature, strength, and persistence of the inducing stress. This thesis proposes several approaches by which the equations can be modified to model the transition from adaptation to apoptosis as a dynamic switch, while taking into account the various hypotheses of cell death mechanisms. Finally, we use recently-developed computational algebra techniques to infer an optimal structure of the UPR network, based solely on the experimental data; the resulting wiring diagram provides insights on elements of the structure of the model that may have been overlooked during the classical (mechanistic) approach to our original data-based model.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Garland, Michael A. « Multi-stress proteomics : The global protein response to multiple environmental stressors in the porcelain crab Petrolisthes cinctipes ». DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1441.

Texte intégral

Résumé :

Global climate change is increasing the number of hot days along the California coast as well as increasing the incidence of off-shore upwelling events that lower the pH of intertidal seawater; thus, intertidal organisms are experiencing an increase in more than one stress simultaneously. This study seeks to characterize the global protein response of the eurythermal porcelain crab Petrolisthes cinctipes to changes in thermal, pH, and tidal regime treatments, either combined or individually. The first experiment examined temperature stress alone and sought to determine the effect of chronic temperature acclimation on the acute heat shock response. We compared the proteomic response of cheliped muscle tissue following a month-long acclimation to either (1) constant 10°C, (2) daily fluctuation from 10-20°C, or (3) daily fluctuation from 10-30°C, all followed by either a 30°C acute heat shock or 10°C control. We found that ATP supply via the phosphagen system, changes in glycolytic enzymes, muscle fiber restructuring, respiratory protein fragmentation, and immunity were primarily affected by acclimation and subsequent heat shock. Acclimation to the “extreme” regimes (10°C and 10-30°C) resulted in the greatest proteomic changes, while acclimation to the moderate regime (10-20°C) resulted in a more mild response to heat shock (i.e., fewer adjustments to relative protein abundance). The second experiment sought to determine the proteomic response of gill tissue following a 17 d acclimation to daily changes in pH (ambient pH 8.1 vs low pH 7.6), tidal regime (constant immersion vs 6 h emersion), and temperature (ambient 11°C vs 22-31°C heat shock during emersion). Low pH alone reduced expression of molecular chaperones of the endoplasmic reticulum, lectins, and serine proteases involved in activating the prophenoloxidase cascade. It also increased the abundance of Na+/K+-ATPase, nitrogen metabolism enzymes, and induced changes in tubulin expression, all suggesting an increase in ammonium excretion. Addition of emersion during low pH reduced the abundance of several metabolic proteins including those involved in the proposed ammonium excretion mechanism, suggesting a decrease in metabolic function in part to prevent toxic accumulation of ammonium in the branchial chambers. Combined pH, emersion, and thermal stress increased the abundance of proteins involved in cuticle binding and crosslinking. These results indicate that the responses to pH, tidal cycle, and temperature are highly dependent on one another and that changes in ER protein maturation, ion transport, immunity, and cuticle structure are the primary biochemical systems impacted by these environmental stressors in crustacean gill.

Styles APA, Harvard, Vancouver, ISO, etc.

45

FALETTI, STEFANIA. « LSD1-DIRECTED THERAPY HINDERS GLIOBLASTOMA BY DEREGULATING ATF4-DEPENDENT INTEGRATED STRESS RESPONSE ». Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/789247.

Texte intégral

Résumé :

Glioblastoma (GBM) is a devastating tumor, whose heterogeneity, poor blood-brain barrier penetration and hierarchical organization obstacle the amelioration of the standard of care. A therapeutic breakthrough may be represented by the eradication of GBM tumor initiating cells (TICs), responsible of its growth and relapse. By exploiting patient-derived TICs and orthotopic xenograft models, I have demonstrated that Lysine-specific histone demethylase 1 (LSD1) is a druggable target in GBM TICs and that a novel, specific LSD1 inhibitor (LSD1i) is brain penetrant and well tolerated. LSD1i impairs growth, viability, stem-like traits and tumorigenic potential of GBM TICs and this phenotype is mirrored by LSD1 genetic targeting. My data point to LSD1 as a novel positive regulator of the activating transcription factor 4 (ATF4), the hub of the Integrated Stress Response (ISR), an adaptive pathway activated in response to nutrient shortage and accumulation of unfolded proteins, stressful conditions to which GBM is often subject. LSD1 targeting sensitizes GBM TICs to stress, triggering a maladaptive response eventually culminating in cell death. Finally, I show that LSD1 and ATF4 may cooperate to regulate the expression of ISR mediators and that LSD1i may deregulate this process by displacing the ATF4 trans-activator CBP from the LSD1-protein complex, thus shedding light on the importance of LSD1 scaffolding functions in GBM TICs. Overall, LSD1-directed therapy is likely a promising strategy to hinder GBM, and its effectiveness independently of GBM TIC heterogeneous molecular landscape places a strong rationale toward the rapid clinical translation of this approach for GBM treatment.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Sommerweiß, Dietlind. « Oleate rescues INS-1E β-cells from palmitate-induced apoptosis by preventing activation of the unfolded protein response ». Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-172386.

Texte intégral

Résumé :

In this project I sought to analyse the effects of different free fatty acids (FFAs) on INS-1E β-cells. The saturated fatty acid palmitate is considered toxic whereas the monounsaturated fatty acid oleate is harmless. In my working hypothesis I assumed an additional protective effect of oleate when used in combination with palmitate. Furthermore I aimed to explore in detail the possible causes and signalling pathways responsible for apoptosis or sustained cell survival. I examined the Endoplasmic Reticulum (ER) stress response, called unfolded protein response (UPR), as one essential criterion deciding about cell death or life. Analysis of viability and apoptosis confirmed the deleterious effect of palmitate on INS-1E β-cells after 24h of incubation. Oleate proved not to be harmful and even reversed the toxicity of palmitate. When the main components of the UPR were assessed using Western blot analyses and quantitative PCR was performed I found positive proof that palmitate activated the UPR and ultimately led to apoptosis. By contrast, oleate completely prevented UPR signalling. I conclude that oleate rescues INS-1E β-cells by inhibiting ER stress and its signalling.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Frigerio, Sara. « Plant response to abiotic stress : analysis of changes in the photosynthetic apparatus at both gene and protein level ». Aix-Marseille 2, 2008. http://www.theses.fr/2008AIX22076.

Texte intégral

Résumé :

In the first part of the work the behaviour of different light harvesting complex (Lhc) subunits, belonging to a highly conserved multigenic family, was analysed in response to different growth conditions in Zea mays. The redundancy of these sequences suggested, in fact, a possible specific role of each gene product in light harvesting and photoprotection, depending on environmental conditions. Plants were grown in different conditions of light and temperature and thylakoid membranes were isolated in order to test the accumulation of different Lhc proteins. Significant differences were found in the accumulation of both major (LHCII) and minor antennae of Photosystem II (PSII). Temperature seemed to play an important role, since the LHCII/minor antenna ratio increased with decreasing temperature, suggesting that the rate of light energy utilization vs excess energy was the driving force for these changes. Low temperature, in fact, is a powerful stress factor since it greatly decreases the electron transport rate at the step of QH2 oxidation by Cyt b6f thus leading to over-reduction of the PQ pool; moreover the decrease of Calvin cycle activity depresses ATP and NADPH utilisation thus making NADP+ unavailable as electron acceptor from PSI. The effect of low temperature is particularly stressing in the case of C4 plants because of their tropical origin. The observed changes included significant variations in pigment composition and activity of Non Photochemical Quenching. These results confirmed the specific role of different antennae in the organization of the Photosystem II and photoprotection. In the second part of this thesis, the attention was focused on the role in acclimation of two major components of stress: ROS production and plastoquinone reduction. To elucidate this problem, the modulation of antenna polypeptides following environmental conditions was analysed using a barley (Hordeum vulgare) mutant, viridis zb63, which lacks Photosystem I, to mimic extreme and chronic over-excitation of Photosystem II. [. . . ]
Dans la première partie du travail, il a été analysé le comportement des différents subunités appartenantes à la famille multigénique du Lhcb, dans réponse à des différentes conditions de croissance en maïs (Zea mays). La redondance de ces séquences, en effet, a suggéré un possible rôle spécifique de chaque produit génique dans la capture de la lumière et dans la photoprotection, sur la base des conditions environnementales. Les plantes ont été poussées en différentes conditions de lumière et température, pour ensuite en isoler les tylacoides au fin de les tester pour l’accumulation des protéines des antennes (Lhc). Des significatives différences ont été relevées dans les antennes, soit majeurs (LHCII) que mineurs, du Photosystème II (PSII) et, en détail, la température a joué un important rôle, puisque le rapport LHCII/antennes mineures a montré une augmentation avec la diminution de la température. Le froid, en effet, est un facteur de stress assez puissant, dès qu’il réduit énormément la vitesse de transport des électrons au niveau de l’oxydation du QH2 de la part du Cytb6f, en déterminant un excès de réduction du plastoquinone. Dans la deuxième partie de cette thèse, la régulation par les conditions environnementales des polypeptides qui constituent l'antenne photosynthétique a été analysée en employant un mutant d’orge (Hordeum vulgare), viridis zb63, qui manque du Photosystème I, ce qui produit la réduction du plastoquinone et mime une surexcitation chronique du Photosystème II. [. . . ]

Styles APA, Harvard, Vancouver, ISO, etc.

48

Mohd, Sukri Nursyuhada. « Influence of hyperthermia and antioxidant supplementation on redox balance and heat shock protein response to exercise ». Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767577.

Texte intégral

Résumé :

Physical activity of moderate intensity and duration leads to healthy biological adaptations in humans. However, very intense and prolonged exercise may induce disruption in redox balance, potentially increasing oxidative stress. In addition, exposure to environmental heat stress and associated hyperthermia further increases oxidative stress and may induce the expression of heat shock proteins. However, antioxidant supplementation is believed to minimise the effect of oxidative stress and may therefore help reduce or limit the heat shock response to exercise heat stress. The first study (Chapter 4) examined whether exertional heat illness (EHI) casualties among military recruits may exhibit greater disturbances in redox balance following exercise compared to non-EHI controls. Nine (n=9) recruits were identified as having suspected EHI during the Loaded March (LM) on day 1, with a peak mean (SD) body core temperature of 40.1 (0.5) °C. Fifteen (n=15) recruits were identified as having suspected EHI during the Log Race (LR) on day 2, with a peak mean (SD) body core temperature of 39.7 (0.5) °C. A further twenty-one (n=21) recruits, which successfully finished both LM and LR events, were treated as controls (CON). Interestingly, the plasma antioxidant concentration was significantly elevated from pre to post-exercise (p < 0.001) for EHI and CON groups, during both LM and LR events, with no changes on lipid peroxide protein carbonyl concentrations. These data suggest there is no increase in lipid peroxide or protein carbonyl level damage in response to intense hyperthermic military exercise, regardless of acute heat illness. It is possible that military training augments the body's defence capabilities, thus reducing oxidative stress and damage induced by free radical production. To date there is a scarcity of data examining the effects of acute intake of antioxidant supplements on oxidative stress and heat shock response during continuous exercise in a hot environment. Hence, the aims of the second study (Chapter 5) were to examine the effects of acute ingestion of Quercetin (Q), Quercetin + vitamin C (QC) or placebo (P) 14 hours before, 2 hours before and every 20 minutes during trials on oxidative stress and heat shock response. In this randomised, crossover study 10 recreationally active males (age 21±2 y, V̇ O2max 54.9±8.4 ml.kg.min-1) completed three running trials at 70% V̇ O2max for 60 minutes in the heat (33.0±0.3°C; 28.5±1.8% relative humidity). Exercise heat stress significantly elevated plasma quercetin (p=0.02), antioxidant power (FRAP) (p < 0.001),plasma heat shock protein 70 (HSP70) (p=0.009) and plasma heat shock protein 90α(HSP90α) (p < 0.001) over time, but no differences were detected between trials. Also, no changes were observed in protein carbonyl concentration. Acute intake of quercetin significantly increased the level of plasma quercetin however, this did not affect the plasma antioxidant capacity or heat shock response to exercise heat stress. The increases in plasma HSP70 and HSP90α concentrations might act as supplementary antioxidants, reducing the oxidative damage reflected in the absence of changes in protein carbonyl. Exercise heat stress is effective in inducing both intracellular HSP70 (muscle and peripheral blood mononuclear cell (PBMC)) and extracellular HSP70 (plasma) concentrations. Thus, the third study (Chapter 6) tested the hypothesis that this acute quercetin supplementation would induce similar trends in plasma HSP70 and intracellular HSP70 concentrations 2 days following exercise heat stress. In this randomised, crossover study, 9 recreationally active males (age 22±2y, V̇ O2max 50.3±3.3ml.kg.min-1) completed three running trials at 70% V̇ O2max for 60 minutes in the heat (32.9±0.3°C; 28.3±1.2% relative humidity). This study demonstrated that there is no positive relationship between both intracellular of HSP70 (muscle and PBMC) and plasma HSP70 (eHSP70) 2 days following exercise heat stress. These data suggest that the release of eHSP70 could originate from others tissue or cells. Additionally, the absence of differences between trials in the expression of muscle HSP70, PBMC HSP70 and plasma HSP70 might indicate it is implausible that quercetin might inhibit the expression of HSP70 in plasma, muscle and PBMC 2 days following the exercise heat stress stimulus. Overall, the results from this thesis emphasise that the hyperthermia experienced in response to exercise and environmental heat stress could potentially influence the human redox response and heat shock response. Besides, there is reasonable evidence that acute quercetin co-ingestion with vitamin C has the potential to improve the bioavailability and bioactive effects of quercetin, however, the effects of quercetin supplementation in reducing oxidative stress in response to exercise heat stress remains to be elucidated. In addition, the anti-oxidative ability of acute ingestion of quercetin to suppress the intracellular and extracellular heat shock response remains uncertain and worthy for further investigation.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Roode, Enrico Carlo. « The effect of exogenous DIM on Brassica napus and its role in response to heavy metal stress ». University of the Western Cape, 2017. http://hdl.handle.net/11394/6242.

Texte intégral

Résumé :

Magister Scientiae - MSc (Biotechnology)
Brassica napus is a plant that is used for human and animal consumption. This plant is also used for phytoremediation due to its relatively higher level of heavy metal tolerance. In South Africa, mining is one of the main drivers of the economy. One of the major negative environmental impacts of mining is heavy metal contamination. Soil metal content can rise to levels that are quite high and can even have a negative impact on the yields of B. napus crop. The glucosinolate-myrosinase system of B. napus is a system that is used as defence against biotic stressors. Indole glucosinolate breakdown products have been proven to enhance the antioxidant capacity of plants. Some have also shown growth promoting properties in plants. We studied the effect of exogenous DIM on B. napus and it role in Zr induced heavy metal stress. Germination percentages revealed that DIM increased germination, Zr application decreased germination and the DIMZr treatment reversed the negative impact of Zr application on B. napus. The effect of treatments on the biomass of B. napus was assessed by determining the dry weights. Results show that exogenous DIM improves biomass. Zr application decreased biomass and DIM-Zr treatment ameliorated the effect of Zr application.
2020-08-31

Styles APA, Harvard, Vancouver, ISO, etc.

50

Gomez, Vargas Javier Alejandro. « Regulation of the signal transduction pathways of the unfolded protein response during chronic and physiological ER stresses ». Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/5760.

Texte intégral

Résumé :

The unfolded protein response (UPR) is activated by protein misfolding stress in the endoplasmic reticulum (ER). The UPR is a transcriptional program that aims to maintain ER folding capacity, where imbalances between protein load and processing ability is termed ER stress. Signal transduction of the UPR begins with 3 ER-resident transmembrane sensors: PERK, IRE1 and ATF6. All sensors initiate downstream signaling cascades which culminate in improved protein folding, transcriptional upregulation of genes encoding ER chaperones, and mechanisms to reduce translational and transcriptional ER load, therefore re-establishing ER homeostasis. The signaling cascades of each sensor are distinct but cooperative, and involve a significant amount of crosstalk, feedback and overlap. Indeed, there are many pathological and physiological conditions have an effect on ER protein burden, and therefore on activation of the UPR. Increases in protein load in professional secretory cells, hypoxic conditions in a tumor mass, obesity all induce cause changes in the ER folding environment. Although we understand how the UPR contributes to relieve ER stress under acute conditions (e.g. pharmacological treatment) much less is understood about the contributions to physiological processes and chronic stress conditions. Our overall goal was to understand how the UPR is activated during physiological settings, the mechanisms it uses to maintain folding capacity under these setting and the specific components responsible for adapting the response to various stresses. We first decided to understand a chronic stress from a transgenic approach. By creating a knockout mouse, the genetic deletion functions as a stress and we can understand its physiological role. By compounding two genetic deletions in UPR components (ATF6α and p58IPK) we provide evidence for the developmental role these components play. Homozygous deletion ATF6α bears no gross histological phenotype yet causes synthetic lethality when combined with p58IPK deletion. This also reveals that the UPR is able to adapt to genetic impairment of protein folding in vivo. Next, to better understand these chronic states, we established an experimentally tractable chronic stress treatment in vivo. Our treatment suppressed ATF6α dependent chaperone expression through an mRNA degradative mechanism, which led to long term changes in UPR expression. We determined that chronic conditions can change the sensitivity of the UPR to ER stress, potentially as an adaptive consequence. We also showed that sensitivity to ER stress can be changed during chronic stress. Finally we simulated the UPR in a computational ordinary differential equation (ODE) model in order to determine how various stresses and component interactions determine the output of the UPR. We built a series of equations to describe the UPR signaling network, entrained it on experimental data and refined it through the use of transgenic knockout cells. Our model was robust enough to recreate experimental measurements of UPR components when tested in parallel with knockout cells. We found that stress sensitivity is dependent on the crosstalk and negative feedback connections of the UPR. This study has enhanced our understanding of activation of the UPR under non-acute settings. It demonstrates that the UPR is a signaling hub with a broad output range that is capable of handling a variable degree of insults because of the intrinsic properties of the signaling network. This provides a better understanding for the contributions of the UPR to physiological stresses and certain chronic diseases.

Styles APA, Harvard, Vancouver, ISO, etc.

Thèses sur le sujet « Stress response protein p66ShcA »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres