Littérature scientifique sur le sujet « Activated Transcription Factor 4 »
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Articles de revues sur le sujet "Activated Transcription Factor 4"
1
Dohm, G. Lynis. « Invited Review : Regulation of skeletal muscle GLUT-4 expression by exercise ». Journal of Applied Physiology 93, no 2 (1 août 2002) : 782–87. http://dx.doi.org/10.1152/japplphysiol.01266.2001.
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The amount of GLUT-4 protein is a primary factor in determining the maximal rate of glucose transport into skeletal muscle. Therefore, it is important that we understand how exercise regulates GLUT-4 expression so that therapeutic strategies can be designed to increase muscle glucose disposal as a treatment for diabetes. Muscle contraction increases the rates of GLUT-4 transcription and translation. Transcriptional control likely requires at least two DNA binding proteins, myocyte enhancer factor-2 and GLUT-4 enhancer factor, which bind to the promoter. Increased GLUT-4 expression may be mediated by the enzyme AMP-activated kinase, which is activated during exercise and has been demonstrated to increase GLUT-4 transcription. Further research needs to be done to investigate whether AMP-activated kinase activates myocyte enhancer factor-2 and GLUT-4 enhancer factor to increase transcription of the GLUT-4 gene.
2
Wang, Jun, Pierre Paradis, Anne Aries, Hiba Komati, Chantal Lefebvre, Hao Wang et Mona Nemer. « Convergence of Protein Kinase C and JAK-STAT Signaling on Transcription Factor GATA-4 ». Molecular and Cellular Biology 25, no 22 (15 novembre 2005) : 9829–44. http://dx.doi.org/10.1128/mcb.25.22.9829-9844.2005.
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ABSTRACT Angiotensin II (AII), a potent vasoactive hormone, acts on numerous organs via G-protein-coupled receptors and elicits cell-specific responses. At the level of the heart, AII stimulation alters gene transcription and leads to cardiomyocyte hypertrophy. Numerous intracellular signaling pathways are activated in this process; however, which of these directly link receptor activation to transcriptional regulation remains undefined. We used the atrial natriuretic factor (ANF) gene (NPPA) as a marker to elucidate the signaling cascades involved in AII transcriptional responses. We show that ANF transcription is activated directly by the AII type 1 receptor and precedes the development of myocyte hypertrophy. This response maps to STAT and GATA binding sites, and the two elements transcriptionally cooperate to mediate signaling through the JAK-STAT and protein kinase C (PKC)-GATA-4 pathways. PKC phosphorylation enhances GATA-4 DNA binding activity, and STAT-1 functionally and physically interacts with GATA-4 to synergistically activate AII and other growth factor-inducible promoters. Moreover, GATA factors are able to recruit STAT proteins to target promoters via GATA binding sites, which are sufficient to support synergy. Thus, STAT proteins can act as growth factor-inducible coactivators of tissue-specific transcription factors. Interactions between STAT and GATA proteins may provide a general paradigm for understanding cell specificity of cytokine and growth factor signaling.
3
Malik, S., et S. K. Karathanasis. « TFIIB-directed transcriptional activation by the orphan nuclear receptor hepatocyte nuclear factor 4. » Molecular and Cellular Biology 16, no 4 (avril 1996) : 1824–31. http://dx.doi.org/10.1128/mcb.16.4.1824.
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The orphan nuclear receptor hepatocyte nuclear factor 4 (HNF-4) is required for development and maintenance of the liver phenotype. HNF-4 activates several hepatocyte-specific genes, including the gene encoding apolipoprotein AI (apoAI), the major protein component of plasma high-density lipoprotein. The apoAI gene is activated by HNF-4 through a nuclear receptor binding element (site A) located in its liver-specific enhancer. To decipher the mechanism whereby HNF-4 enhances apoAI gene transcription, we have reconstituted its activity in a cell-free system. Functional HNF-4 was purified to homogeneity from a bacterial expression system. In in vitro transcription assays employing nuclear extract from HeLa cells, which do not contain HNF-4, recombinant HNF-4 stimulated transcription from basal promoters linked to site A. Activation by HNF-4 did not exhibit a ligand requirement, but phosphorylation of HNF-4 in the in vitro transcription system was observed. The activation function of HNF-4 was localized to a domain displaying strong homology to the conserved AF-2 region of nuclear receptors. Dissection of the transcription cycle revealed that HNF-4 activated transcription by facilitating assembly of a preinitiation complex intermediate consisting of TBP, the TATA box-binding protein component of TFIID and TFIID, via direct physical interactions with TFIIB. However, recruitment of TFIIB by HNF-4 was not sufficient for activation, since HNF-4 deletion derivatives lacking AF-2 bound TFIIB. On the basis of these results, HNF-4 appears to activate transcription at two distinct levels. The first step involves AF-2-independent recruitment of TFIIB to the promoter complex; the second step is AF-2 dependent and entails entry of preinitiation complex components acting downstream of TFIIB.
4
Zheng, Donghai, Paul S. MacLean, Steven C. Pohnert, John B. Knight, Ann Louise Olson, William W. Winder et G. Lynis Dohm. « Regulation of muscle GLUT-4 transcription by AMP-activated protein kinase ». Journal of Applied Physiology 91, no 3 (1 septembre 2001) : 1073–83. http://dx.doi.org/10.1152/jappl.2001.91.3.1073.
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Skeletal muscle GLUT-4 transcription in response to treatment with 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), a known activator of AMP-activated protein kinase (AMPK), was studied in rats and mice. The increase in GLUT-4 mRNA levels in response to a single subcutaneous injection of AICAR, peaked at 13 h in white and red quadriceps muscles but not in the soleus muscle. The mRNA level of chloramphenicol acyltransferase reporter gene which is driven by 1,154 or 895 bp of the human GLUT-4 proximal promoter was increased in AICAR-treated transgenic mice, demonstrating the transcriptional upregulation of the GLUT-4 gene by AICAR. However, this induction of transcription was not apparent with 730 bp of the promoter. In addition, nuclear extracts from AICAR-treated mice bound to the consensus sequence of myocyte enhancer factor-2 (from −473 to −464) to a greater extent than from saline-injected mice. Thus AMP-activated protein kinase activation by AICAR increases GLUT-4 transcription by a mechanism that requires response elements within 895 bp of human GLUT-4 proximal promoter and that may be cooperatively mediated by myocyte enhancer factor-2.
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Rengarajan, Jyothi, Kerri A. Mowen, Kathryn D. McBride, Erica D. Smith, Harinder Singh et Laurie H. Glimcher. « Interferon Regulatory Factor 4 (IRF4) Interacts with NFATc2 to Modulate Interleukin 4 Gene Expression ». Journal of Experimental Medicine 195, no 8 (8 avril 2002) : 1003–12. http://dx.doi.org/10.1084/jem.20011128.
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Proteins of the nuclear factor of activated T cells (NFAT) family of transcription factors are critical for lymphocyte activation in the immune system. In particular, NFATs are important regulators of inducible IL-4 gene expression. Interferon regulatory factor 4 (IRF4) is an immune system–restricted interferon regulatory factor that is required for lymphocyte activation, but its molecular functions in the T lineage remain to be elucidated. We demonstrate that IRF4 potently synergizes with NFATc2 to specifically enhance NFATc2-driven transcriptional activation of the IL-4 promoter. This function is dependent on the physical interaction of IRF4 with NFATc2. IRF4 synergizes with NFATc2 and the IL-4–inducing transcription factor, c-maf, to augment IL-4 promoter activity as well as to elicit significant levels of endogenous IL-4 production. Furthermore, naïve T helper cells from mice lacking IRF4 are compromised severely for the production of IL-4 and other Th2 cytokines. The identification of IRF4 as a partner for NFATc2 in IL-4 gene regulation provides an important molecular function for IRF4 in T helper cell differentiation.
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Moon, Jong-Seok, Hee Eun Kim, Eunjin Koh, Se Ho Park, Won-Ji Jin, Byeong-Woo Park, Sahng Wook Park et Kyung-Sup Kim. « Krüppel-like Factor 4 (KLF4) Activates the Transcription of the Gene for the Platelet Isoform of Phosphofructokinase (PFKP) in Breast Cancer ». Journal of Biological Chemistry 286, no 27 (17 mai 2011) : 23808–16. http://dx.doi.org/10.1074/jbc.m111.236737.
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Krüppel-like factor 4 (KLF4) is a transcription factor that plays an important role in cell differentiation, proliferation, and survival, especially in the context of cancers. This study revealed that KLF4 activates glycolytic metabolism in breast cancer cells by up-regulating the platelet isoform of phosphofructokinase (PFKP). KLF4 activated the transcription of the PFKP gene by directly binding to the PFKP promoter. Whereas glucose uptake and lactate production were inhibited by the knockdown of KLF4, they were activated by the overexpression of KLF4. Unlike PFKP, the expressions of the other isoforms of phosphofructokinase and glycolytic genes were unaffected by KLF4. The human breast cancer tissues showed a close correlation between KLF4 and PFKP expression. This study also showed that PFKP plays a critical role in cell proliferation in breast cancer cells. In conclusion, it is suggested that KLF4 plays a role in maintenance of high glycolytic metabolism by transcriptional activation of the PFKP gene in breast cancer cells.
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Georas, Steve N., John E. Cumberland, Thomas F. Burke, Rongbing Chen, Ulrike Schindler et Vincenzo Casolaro. « Stat6 Inhibits Human Interleukin-4 Promoter Activity in T Cells ». Blood 92, no 12 (15 décembre 1998) : 4529–38. http://dx.doi.org/10.1182/blood.v92.12.4529.
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Abstract The differentiation of naive T-helper (Th) cells into cytokine-secreting effector Th cells requires exposure to multiple signals, including exogenous cytokines. Interleukin-4 (IL-4) plays a major role in this process by promoting the differentiation of IL-4–secreting Th2 cells. In Th2 cells, IL-4 gene expression is tightly controlled at the level of transcription by the coordinated binding of multiple transcription factors to regulatory elements in the proximal promoter region. Nuclear factor of activated T cell (NFAT) family members play a critical role in regulating IL-4 transcription and interact with up to five sequences (termed P0 through P4) in the IL-4 promoter. The molecular mechanisms by which IL-4 induces expression of the IL-4 gene are not known, although the IL-4–activated transcription factor signal transducer and activator of transcription 6 (Stat6) is required for this effect. We report here that Stat6 interacts with three binding sites in the human IL-4 promoter by electrophoretic mobility shift assays. These sites overlap the P1, P2, and P4 NFAT elements. To investigate the role of Stat6 in regulating IL-4 transcription, we used Stat6-deficient Jurkat T cells with different intact IL-4 promoter constructs in cotransfection assays. We show that, whereas a multimerized response element from the germline IgE promoter was highly induced by IL-4 in Stat6-expressing Jurkat cells, the intact human IL-4 promoter was repressed under similar conditions. We conclude that the function of Stat6 is highly dependent on promoter context and that this factor promotes IL-4 gene expression in an indirect manner.
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Georas, Steve N., John E. Cumberland, Thomas F. Burke, Rongbing Chen, Ulrike Schindler et Vincenzo Casolaro. « Stat6 Inhibits Human Interleukin-4 Promoter Activity in T Cells ». Blood 92, no 12 (15 décembre 1998) : 4529–38. http://dx.doi.org/10.1182/blood.v92.12.4529.424k39_4529_4538.
Texte intégralRésumé :
The differentiation of naive T-helper (Th) cells into cytokine-secreting effector Th cells requires exposure to multiple signals, including exogenous cytokines. Interleukin-4 (IL-4) plays a major role in this process by promoting the differentiation of IL-4–secreting Th2 cells. In Th2 cells, IL-4 gene expression is tightly controlled at the level of transcription by the coordinated binding of multiple transcription factors to regulatory elements in the proximal promoter region. Nuclear factor of activated T cell (NFAT) family members play a critical role in regulating IL-4 transcription and interact with up to five sequences (termed P0 through P4) in the IL-4 promoter. The molecular mechanisms by which IL-4 induces expression of the IL-4 gene are not known, although the IL-4–activated transcription factor signal transducer and activator of transcription 6 (Stat6) is required for this effect. We report here that Stat6 interacts with three binding sites in the human IL-4 promoter by electrophoretic mobility shift assays. These sites overlap the P1, P2, and P4 NFAT elements. To investigate the role of Stat6 in regulating IL-4 transcription, we used Stat6-deficient Jurkat T cells with different intact IL-4 promoter constructs in cotransfection assays. We show that, whereas a multimerized response element from the germline IgE promoter was highly induced by IL-4 in Stat6-expressing Jurkat cells, the intact human IL-4 promoter was repressed under similar conditions. We conclude that the function of Stat6 is highly dependent on promoter context and that this factor promotes IL-4 gene expression in an indirect manner.
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Carrozza, M. J., et N. A. DeLuca. « Interaction of the viral activator protein ICP4 with TFIID through TAF250. » Molecular and Cellular Biology 16, no 6 (juin 1996) : 3085–93. http://dx.doi.org/10.1128/mcb.16.6.3085.
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ICP4 of herpes simplex virus is responsible for the activation of viral transcription during infection. It also efficiently activates and represses transcription in vitro depending on the promoter context. The contacts made between ICP4 and the cellular proteins that result in activated transcription have not been identified. The inability of ICP4 to activate transcription with TATA-binding protein in place of TFIID and the requirement for an initiator element for efficient ICP-4-activated transcription suggest that coactivators, such as TBP-associated factors, are involved (B. Gu and N. DeLuca, J. Virol. 68:7953-7965, 1994). In this study we showed that ICP4 activates transcription in vitro using an immunopurified TFIID, indicating that TBP-associated factors may be a sufficient subset of coactivators for ICP4-activated transcription. Similar to results seen in vivo, the presence of the ICP4 C-terminal region (amino acids 774 to 1298) was important for activation in vitro. With epitope-tagged ICP4 molecules in immunoaffinity experiments, it was shown that the C-terminal region was also required for ICP4 to interact with TFIID present in a crude transcription factor fraction. In the same assay, ICP4 was unable to interact with the basal transcription factors, TFIIB, TFIIE, TFIIF, and TFIIH and RNA polymerase II. ICP4 could also interact with TBP, independent of the C-terminal region. However, reflective of the interaction between ICP4 and TFIID, the ICP4 C-terminal region was required for an interaction with FAF250-TBP complexes and with TAF250 alone. Therefore, the interfaces or conformation of TBP mediating the interaction between ICP4 and TBP in solution is probably masked when TBP is bound to TAF250. With a series of mutant ICP4 molecules purified from herpes simplex virus-infected cells, it was shown that ICP4 molecules that can bind DNA and interact with TAF250 could activate transcription. Taken together, these results demonstrate that ICP4 interaction with TFIID involves the TAF250 molecule and the C-terminal region of ICP4 and that this interaction is part of the mechanism by which ICP4 activates transcription.
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Lopez, Alex B., Chuanping Wang, Charlie C. Huang, Ibrahim Yaman, Yi Li, Kaushik Chakravarty, Peter F. Johnson et al. « A feedback transcriptional mechanism controls the level of the arginine/lysine transporter cat-1 during amino acid starvation ». Biochemical Journal 402, no 1 (25 janvier 2007) : 163–73. http://dx.doi.org/10.1042/bj20060941.
Texte intégralRésumé :
The adaptive response to amino acid limitation in mammalian cells inhibits global protein synthesis and promotes the expression of proteins that protect cells from stress. The arginine/lysine transporter, cat-1, is induced during amino acid starvation by transcriptional and post-transcriptional mechanisms. It is shown in the present study that the transient induction of cat-1 transcription is regulated by the stress response pathway that involves phosphorylation of the translation initiation factor, eIF2 (eukaryotic initiation factor-2). This phosphorylation induces expression of the bZIP (basic leucine zipper protein) transcription factors C/EBP (CCAAT/enhancer-binding protein)-β and ATF (activating transcription factor) 4, which in turn induces ATF3. Transfection experiments in control and mutant cells, and chromatin immunoprecipitations showed that ATF4 activates, whereas ATF3 represses cat-1 transcription, via an AARE (amino acid response element), TGATGAAAC, in the first exon of the cat-1 gene, which functions both in the endogenous and in a heterologous promoter. ATF4 and C/EBPβ activated transcription when expressed in transfected cells and they bound as heterodimers to the AARE in vitro. The induction of transcription by ATF4 was inhibited by ATF3, which also bound to the AARE as a heterodimer with C/EBPβ. These results suggest that the transient increase in cat-1 transcription is due to transcriptional activation caused by ATF4 followed by transcriptional repression by ATF3 via a feedback mechanism.
Thèses sur le sujet "Activated Transcription Factor 4"
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PASINI, SILVIA. « Role of activated transcription factor 4 (ATF4) in learning and memory ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/27132.
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The aim of this study is to understand the role of Activated Transcription Factor 4 (ATF4) in the processes of learning and memory. The topic of learning and memory has always aroused great interest from time immemorial and although a lot of researches have been focused on this subject for a long time, many mechanisms have not yet been fully understood.
Identifying the players and the mechanisms involved in learning and memory is of utmost importance because deficits in these cognitive functions are symptoms of common neurological diseases like stoke, depression, dementia and Alzheimer’s disease, one of the most wide spread neurodegenerative disease.
It has already been established that new gene expression and protein synthesis are required for long term memory, providing the basis to think that transcription factors may play a key role in these processes. Several studies have demonstrated the involvement of different transcription factors in memory formation such as cAMP response element binding protein (CREB), CCAAT enhancer binding protein (C/EBP), activated protein 1 (AP1), early growth response factor (Egr) and Rel/nuclear factor kB (Rel/NFkB).
Very little is known about the involvement of another transcription factor, Activated Transcription Factor 4. ATF4 is a member of the activated transcription factor (ATF)/cyclic AMP response element binding protein (CREB) family. It was originally described as a repressor of CRE-dependent gene transcription but recent studies have shown it to be a transcriptional activator. It is also a stress responsive gene, regulating the adaptation of cells to stress stimuli such as anoxia, endoplasmic reticulum stress and oxidative stress. ATF4 plays an essential role in development, and is particularly required for proper skeletal and eye development and is also involved in tumor progression and metastasis.
ATF4 has always been reported as a memory repressor that blocks new gene expression required for memory formation but no study has ever investigated it in a specific and direct way. The aim of this thesis is to study, in a specific and direct manner, the role of ATF4 in the processes of learning and memory. To reach this goal, ATF4 expression was modified in mouse hippocampi, the brain region mainly involved in learning and memory, with the injection of lentivirus carrying ATF4 gene, for the gain-of-function analysis, and lentivirus carrying shATF4, for the loss-of-function studies.
Before starting the experiments of ATF4 overexpression and downregulation, preliminary experiments were conducted to set up the injection coordinates to target the mouse hippocampi, to verify the lentiviral tropism and most importantly to evaluate the lentiviral spread, within the hippocampus, after the injection.
The consequence of ATF4 gain- and loss-of-function was then studied in the performance of standard behavioral tests such as Water Maze tests and Fear Conditioning, widely used to assess spatial and associative memory respectively. The behavioral test results showed that ATF4 protein overexpression enhances spatial memory, under the weak training paradigm in the Morris Water Maze test, and associative memory while ATF4 downregulation impairs spatial memory under the standard training condition.
After completing the behavioral tests, ATF4 overexpressed and downregulated mice were subjected to electrophysiological and neuronal spine analysis to verify if the alteration in cognitive functions, as a result of ATF4 modification, is supported by changes in synaptic potentiation and spine density and morphology.
Long Term Potentiation (LTP) is a long lasting enhancement in neuronal transmission and is widely considered as a cellular model of learning and memory in the central nervous system. The long-term memory impairment of ATF4 downregulated mice is supported by electrophysiological analysis, in which ATF4 downregulated slices showed an impairment in LTP. Unexpectedly, LTP impairment was also found in ATF4 overexpressed slices, maybe due to the difference in the time between the injection and the behavioral tests or the electrophysiological recordings.
Most of the intracellular pathways responsible for LTP require new gene expression and protein synthesis. This, in turn, leads to morphological changes required to sustain the enhancement of signal transmission. One of these morphological changes is the modification of the density and the morphology of dendritic spines. ATF4 up- and downregulation in hippocampal neurons does not affect spine density but ATF4 overexpression causes a significant increase in the percentage of mushroom spines as compared to that found after ATF4 downregulation. Mushroom spines with a large head are the most stable neuronal spines and contribute to strong synaptic connections, hence it has been hypothesized that they represent the “memory spines”.
Collectively, these results support the hypothesis that the transcription factor ATF4 plays a positive role in synaptic plasticity and memory formation. Further studies need to be done to understand the molecular mechanisms through which ATF4 acts.
This thesis represents only a step on the road towards understanding the complicate mechanisms of learning and memory, not forgetting that the most important discoveries were the result of small knowledge acquired step by step.
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Kaikkonen, L. (Leena). « p38 mitogen-activated protein kinase and transcription factor GATA-4 in the regulation of cardiomyocyte function ». Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526205038.
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Abstract Cardiovascular diseases are the leading causes of death in the developed countries and their incidence is not expected to decrease in the future. There is a lifetime risk of one in five of developing heart failure, which still has poor prognosis and current treatments only cover part of the pathophysiology behind this syndrome. Pathological processes contributing to heart failure include cardiac hypertrophy and remodeling, which involves neurohumoral activation, reactivation of fetal genes, impaired Ca2+ cycling, increased apoptosis, and increased fibrosis. Intracellular signalling pathways and transcription factors mediating the response to various extracellular stresses have a key role in the regulation of myocardial remodeling and they are investigated in order to develop new approaches for the treatment of heart failure. The aim of this thesis was to elucidate roles of mitogen-activated protein kinases (MAPKs) and transcription factor GATA-4 in the regulation of cardiomyocyte function in cell cultures, and in hearts ex vivo and in vivo. The main findings were that (i) Inhibition of p38α MAPK enhanced function of sarco/endoplasmic reticulum Ca2+ -ATPase and thus cardiac contractility by increasing phosphorylation of protein phosphatase inhibitor-1 and phospholamban, (ii) p38 MAPK isoforms p38α and p38β regulated promoter activity of B-type natriuretic peptide via distinct pathways, (iii) p38α and p38β MAPKs also had different effects on gene expressions related to fibrosis and hypertrophy, and (iv) p38 and ERK1/2 MAPKs mediated stretch-induced activation of GATA-4 by phosphorylation at Ser 105. GATA-4 also seems to be regulated by ubiquitination. This study provides novel data of p38 MAPK and GATA-4 in the regulation of cardiomyocyte function. Inhibition of p38α MAPK could be beneficial in the treatment of heart failure. Also GATA-4 is a potential target for treatment of cardiovascular diseasesTiivistelmä Sydän- ja verisuonisairaudet ovat yleisin kuolinsyy länsimaissa, eikä niiden ilmaantuvuus tule vähenemään lähitulevaisuudessa. Elinikäinen riski sairastua sydämen vajaatoimintaan on 20 %, ja sydämen vajaatoiminnan ennuste on edelleen huono. Nykyisillä hoitomuodoilla voidaan puuttua vain osittain sydämen vajaatoiminnan patofysiologisiin mekanismeihin. Sydämen vajaatoiminnan kehittymiseen liittyvät sydänlihaksen liikakasvu ja uudelleenmuovautumisprosessi, johon liittyy neurohumoraalinen aktivaatio, sikiöaikaisten geenien uudelleenilmentyminen, häiriöt solunsisäisessä Ca2+-viestinnässä sekä lisääntynyt ohjelmoitu solukuolema ja sidekudoksen muodostuminen sydämeen. Solunsisäisillä viestinvälitysketjuilla sekä transkriptiotekijöillä, jotka vastaavat solunulkoisten ärsykkeiden välittämisestä solun sisällä, on keskeinen rooli edellämainittujen prosessien säätelyssä. Uusien lähestymistapojen kehittäminen sydämen vajaatoiminnan hoitoon edellyttää myös solunsisäisen viestinvälityksen ja geenien säätelyn mekanismien selvittämistä. Tämän väitöstyön tavoite oli selvittää p38 mitogeeniaktivoituvan proteiinikinaasin (p38 MAPK) ja transkriptiotekijä GATA-4:n merkitystä sydämen vajaatoiminnan patogeneesissä soluviljelymalleissa. Päälöydöksiä olivat: (i) p38α MAPK -isoformin estäminen paransi kalsiumia solulimakalvostoon pumppaavan SERCA2a:n toimintaa ja sydänlihassolun supistumiskykyä lisäämällä fosfolambaanin ja proteiinifosfataasi-inhibiittori-1:n fosforylaatiota. (ii) p38 MAPK isoformit p38α ja p38β säätelivät B-tyypin natriureettisen peptidin geenin promoottorialuetta erillisten reittien kautta. (iii) p38α ja p38β isoformit vaikuttivat myös eri tavoin sydämen sidekudoksen muodostumiseen ja hypertrofiaan liittyvien geenien ilmentymiseen. (iv) p38 ja ERK1/2 välittävät venytyksen aiheuttaman GATA-4:n aktivaation fosforyloimalla seriini-105 fosforylaatiopaikan. Lisäksi GATA-4:n toimintaa säädellään ubiquitinaation avulla. Tämä tutkimus tuo uutta tietoa p38 MAPK:n ja GATA-4:n rooleista sydämen vajaatoiminnan kehittymisessä. p38α-isoformin toiminnan estäminen voisi olla hyödyllinen hoitomuoto sydämen vajaatoiminnassa. Myös GATA-4 on potentiaalinen lääkehoidon kohde sydänsairauksien hoidossa
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Arpiainen, S. (Satu). « Transcriptional regulation of the hepatic cytochrome P450 2a5 gene ». Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514285653.
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Abstract
Cytochrome P450 (CYP) enzymes are the major metabolizers of xenobiotics, e.g. drugs, and environmental toxins. Thus, changes in CYP expression have an important impact on drug metabolism and susceptibility to chemical toxicity.
In the present study, the transcriptional mechanisms of both constitutive and inducible regulation of the Cyp2a5 gene in mouse liver were investigated. Mouse primary hepatocyte cultures were used as the main model system together with cell and molecular biology methods.
The key activation regions of the Cyp2a5 5' promoter were determined using reporter gene assays. Two major transcription activation sites of the Cyp2a5 5' promoter, called the proximal and the distal, were found. Transcription factors hepatocyte nuclear factor-4 (HNF-4) and nuclear factor I were shown to bind to the proximal promoter. Aryl hydrocarbon receptor nuclear translocator (ARNT) and upstream stimulatory factor bound to a common palindromic E-box element in the distal promoter region. All three response elements were shown to be essential for constitutive expression of CYP2A5 in murine hepatocytes. ARNT appeared to control Cyp2a5 transcription without a heterodimerization partner suggesting active involvement of the ARNT homodimer in mammalian gene regulation.
Aryl hydrocarbon receptor (AHR) ligands were shown to induce Cyp2a5 transcriptionally by an AHR-dependent mechanism, and established Cyp2a5 as a novel AHR-regulated gene. The AHR response element and the E-box, identified in these studies, were located near to each other and close to a separately defined nuclear factor (erythroid-derived 2)-like 2 binding site in the distal region of the Cyp2a5 promoter, suggesting cooperation between these elements.
Peroxisome proliferator-activated receptor gamma coactivator-1α was shown to up-regulate Cyp2a5 transcription through coactivation of HNF-4α. This indicates that xenobiotic metabolism can be regulated by modification of co-activation.
The present results show that CYP2A5 is regulated by several different cross-regulatory pathways. The regulatory mechanisms involved in the transcription of the Cyp2a5 gene may also control other CYP genes, especially the human ortholog CYP2A6, and may explain some of the individual variations in the metabolism of xenobiotics.
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Houlard, Martin. « Étude de l'adressage et de l'implication nucléaire du proto-oncogène Vav-1 ». Paris 7, 2002. http://www.theses.fr/2002PA077098.
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Mak, Man-chi. « Characterization of transcription factor nuclear factor of activated T-cells 5, in knockout embryos and mice ». Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41633684.
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Arabanian, Laleh Sadat. « Role of NFAT (Nuclear Factor of Activated T Cells) Transcription Factors in Hematopoiesis ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-99739.
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Understanding the transcriptional mechanisms that control hematopoiesis and the interaction between hematopoietic stem cells and the bone marrow (BM) microenvironment in vivo is of considerable interest. The calcineurin-dependent transcription factor NFAT (Nuclear Factor of Activated T cells) is known as master regulator of cytokine production in T lymphocytes and therefore central for T cell-dependent immune reactions, but has also been shown to regulate a process of differentiation and tissue adaptation in various cell types. The activation of NFAT is dependent on the calcium level within the cell. In resting cells, calcium levels are low and NFAT is cytoplasmic and inactive. A sustained increase in the internal calcium concentration within an external stimuli leads to activation of the calcium-dependent calcineurin, followed by dephosphorylation and nuclear translocation of NFAT. We have previously shown that NFATc2, a member of the NFAT family, is expressed in CD34+ hematopoietic stem cells (HSC). A mouse model harboring NFATc2 deficiency provides the opportunity for in vivo investigation of the role of NFATc2 in hematopoiesis.
Our recent observations showed that aged mice lacking the transcription factor NFATc2 develop peripheral blood anemia and thrombocytopenia, BM hypoplasia and extramedullary hematopoiesis in spleen and liver. The proliferation and differentiation of NFATc2-deficient hematopoietic stem cells ex vivo, however, was found to be intact. It remained therefore unclear whether the disturbed hematopoiesis in NFATc2-deficient mice was caused by the hematopoietic or the stroma component of the BM hematopoietic niche. In the current study we dissected the relative contribution of hematopoietic and stroma cells to the phenotype of the NFATc2-deficent mice by transplanting immuno-magnetically purified NFATc2-deficient (KO) HSCs to lethally irradiated wild type (WT) mice, and vice versa. After a post-transplantation period of 6-8 months, peripheral blood, BM as well as spleen and liver of the transplanted animals were analyzed and compared to WT and KO mice transplanted with control cells.
Transplantation of NFATc2-deficient HSCs into WT recipients (KO WT) induced similar hematological abnormalities as those occurring in non-transplanted KO mice or in KO mice transplanted with KO cells (KO KO). Compared to WT mice transplanted with WT cells (WT WT), KO WT mice showed evidence of anemia, thrombocytopenia and a significantly reduced number of hematopoietic cells in their BM. Likewise, KO WT mice developed clear signs of extramedullary hematopoiesis in spleen and liver, which was not the case in WT WT control animals. In addition to the hematopoietic abnormalities, transplantation of NFATc2-deficient HSC also induced osteogenic abnormalities such as BM sclerosis and fibrosis in WT mice. This phenomenon was rather subtle and of incomplete penetrance, but never seen in mice transplanted with WT cells. These data demonstrate for the first time, that the NFATc2 transcription factor directly regulates the intrinsic function of hematopoietic stem cells in vivo. However, the transcriptional targets for NFAT in these cells are yet unknown. In addition to hematopoietic stem cells, NFATc2 has been shown to be expressed in a lineage-specific manner during myeloid differentiation and, notably, is maintained during megakaryopoiesis while it is suppressed during the differentiation of neutrophils. Bone marrow megakaryocytes are the precursors of peripheral blood platelets and therefore constitute an integral part of primary hemostasis, thrombosis and wound healing. The biological role of NFAT in megakaryocytes is unknown. We have recently shown that NFATc2 is not necessary for megakaryocytic differentiation. On the other hand, recent evidence suggests that NFATc2 is required for the transcription of specific megakaryocytic genes. In this study, we showed that activation of the calcineurin/NFAT pathway in either primary megakaryocytes or CMK megakaryocytic cells forces the cells to go into apoptosis. Cell death in megakaryocytes is induced by treating the cells with the calcium ionophore ionomycin and suppressed by either the pan-caspase inhibitor zVAD or the calcineurin inhibitor cyclosporin A (CsA). Ionomycin stimulation of megakaryocytes leads to the expression of Fas Ligand (FASLG), a pro-apoptotic member of the tumor necrosis factor superfamily. Expression of FASLG was detectable as early as four hours after stimulation on the membrane of ionomycin-treated megakaryocytes, was augmented in cells stably overexpressing NFATc2, and was suppressed in cells either pretreated with CsA or expressing the specific peptide inhibitor of NFAT, VIVIT.
To investigate the physiological relevance of FASLG expression on megakaryocytes, we performed co-cultures of megakaryocytes with Fas-expressing T-lymphocytes, in which CMK cells were left either unstimulated or pre-stimulated with ionomycin and then added to Jurkat cells. The presence of ionomycin-stimulated CMK cells, but not of unstimulated cells or cells stimulated in the presence of CsA, significantly induced apoptosis in Jurkat cells. Overexpression of NFATc2 in CMK cells enhanced their potency to induce apoptosis in Jurkat cells, while cells expressing VIVIT were less effective. Apoptosis induction of Jurkat cells by stimulated CMK cells was partially blocked by the presence of either a neutralizing antibody against FASLG or an antagonistic antibody to Fas during the co-culture period, indicating involvement of the FASLG/Fas apoptosis pathway. These results represent the first clear evidence for a biological function of the calcineurin/NFAT pathway in megakaryocytes, namely the regulation of Fas/FASLG-dependent apoptosis. Second, they underline that the biological role of megakaryocytes is not restricted to the production of proteins and other cellular structures for platelet assembly, but that this population of cells fulfills an independent regulatory function in the context of the surrounding tissue.
Finally, we have identified by RNA sequencing analysis of NFATc2-expressing and -deficient cells, the entire set of genes which is induced by NFATc2 in stimulated megakaryocytes. Functional pathway analysis suggests an involvement of NFATc2 in pro-inflammatory pathways in these cells. The significance of these findings has to be addressed in further studies.
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Ulrich, Jason Daniel. « The regulaton and function of nuclear factor of activated T-cells in neurons ». Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/2782.
Texte intégralRésumé :
Ca2+-dependent transcription is a fundamental process by which neurons translate activation experience into cellular level adaptations. The nuclear factor of activated T-cells (NFAT) family of proteins comprise four Ca2+/CaN-dependent transcription factors that are widely expressed throughout virtually all tissues. Within neurons, NFAT dependent signaling is critical for axonal development, regulation of synapse number and efficacy, and survival. Furthermore, NFAT is implicated in activity dependent regulation of genes involved in synaptic transmission, learning and memory, mood, and pain sensation. NFAT is activated upon elevations in intracellular Ca2+, which results in CaN -dependent dephosphorylation of multiple serine residues within an N-terminal regulatory region. NFAT dephosphorylation permits NFAT translocation to the nucleus, where it can regulate gene expression, frequently co-operatively with other transcription factors, including AP-1 and MEF2. NFAT activation is opposed or terminated by several kinases, including CK1 and GSK3. Despite the importance of NFAT proteins as regulators of Ca2+-dependent transcription, little is known about the regulation and function of specific NFAT isoforms within neurons.
In Aim 1 of this thesis I characterized the differential activation of NFATc3 and NFATc4 in DRG neurons. While NFATc3 rapidly translocates the nucleus upon Ca2+-influx through voltage-gated calcium channels, NFATc4 remained remarkably intransient. Modular substitution of NFATc3 regulatory elements increased the rate or retention of NFATc4, whereas converse substitutions of NFATc4 regulatory elements into NFATc3 decreased NFATc3 nuclear translocation. The activation of NFATc4 appears to be inhibited by preferential phosphorylation by kinases, such as GSK3, which counteract CaN-dependent dephosphorylation. In Aim 2 I investigated the role of NFATc3 in hippocampal neurons. While the majority of NFAT reports in neurons have focused on NFATc4, my data suggest that NFATc3 is the predominantly expressed isoform in hippocampal neurons and is critical for depolarization-induced NFAT target gene expression. I further characterized NFATc3 KO mice in a battery of behavioral assays to test whether loss of NFATc3 expression would affect the baseline anxiety/depression state of the animal, or if NFATc3 was critical for learning and memory. Taken together, my data suggest that NFATc3 is important for NFAT-dependent gene expression in central and peripheral neurons and that distinct regulation of NFAT isoforms within neurons may underlie isoform-specific effects on gene expression.
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Rosso, Michele <1984>. « Role of the Transcription Factor Sox2 in the Osteogenic Lineage ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6489/4/rosso_michele_tesi.pdf.
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The Sox2 transcription factor is modified by sumoylation at the K247 position although the addition of SUMO1 and Pias1 promotes the sumoylation of Sox2 at the additional K123 site. The role of sumoylation on Sox2 biological functions was analyzed by comparing the activity of WT and sumoylation mutants on the transcription of the FGF4 gene in HeLa cells and on the downregulation of the Wnt pathwayvin 293T cells. When SUMO1 and PIAS1 promote the sumoylation of WT Sox2, the transcriptional activity of the FGF4 promoter is inhibited showing that Sox2 sumoylation is necessary for the repression function. However, there is no effect of Sox2 sumoylation on β-Catenin activity.
Since we were interested in osteoblast differentiation we set up an inducible system for Sox2 in primary osteoblasts. Following Sox2 doxycycline induction, 158 genes were differentially expressed: 120 up-regulated and 38 down-regulated. We annotated as direct Sox2 targets a number of genes involved in osteoblast biology and we further analyzed 3 of them involved in the BMP pathway. The results show that Sox2 regulates the BMP pathway without affecting SMAD phosphorylation, and that Sox2 sumoylation is not necessary for this function.
We also found that genes involved in the Hippo pathway were direct Sox2 targets. As the Hippo pathway is activated by Sox2 and Sox2 interacts with the NF2 promoter, we checked the effect of Sox2 on the expression of NF2. We showed that Sox2 down-regulates the transcriptional activity of the NF2 promoter, allowing the transcription of the YAP/TEAD genes in osteoblasts, thus acting as an upstream regulator of the Hippo pathway. We conclude that Sox2 induction in osteoblasts triggers FGF dependent inhibition of the BMP, Wnt and Hippo pathways.
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Brehm, Alexander Jorg Georg. « Octamer-dependent transcriptional activation by the embryonal transcription factor Oct-4 ». Thesis, Open University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338344.
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Hilton, Traci Leigh. « Dual function of TAF1 in basal and activated cyclin D1 transcription / ». Thesis, Connect to this title online ; UW restricted, 2003. http://hdl.handle.net/1773/6275.
Texte intégralLivres sur le sujet "Activated Transcription Factor 4"
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Simeone, Timothy A. Ketogenic Diet and PPARgamma. Sous la direction de Detlev Boison. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190497996.003.0020.
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The ketogenic diet (KD) is an effective therapy for many patients with refractory epilepsy. It engages a wide array of antioxidant and anti-inflammatory processes and improves mitochondrial function, which is thought to underlie its neuroprotective, antiseizure, and disease-modifying effects. Potential roles of ketone bodies in these mechanisms are discussed elsewhere in this volume. This chapter focuses on the role of KD fatty acids as potential ligands for the nutritionally regulated nuclear transcription factor peroxisome proliferator activated receptor gamma (PPARgamma). PPARgamma regulates many of the pathways identified in the mechanism of the KD and, in recent years, has become a potential therapeutic target for neurodegenerative diseases. This chapter reviews what is known concerning PPARgamma in the brain, the evidence that PPARgamma has neuroprotective and antiseizure properties, and the evidence suggesting that PPARgamma may be involved in the antiseizure mechanisms of the ketogenic diet.
Chapitres de livres sur le sujet "Activated Transcription Factor 4"
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Gogliettino, Alex R., et Andrew J. Kennedy. « Transcription Factor 4 ». Dans Encyclopedia of Signaling Molecules, 5600–5607. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-67199-4_101934.
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Gogliettino, Alex R., et Andrew J. Kennedy. « Transcription Factor 4 ». Dans Encyclopedia of Signaling Molecules, 1–8. New York, NY : Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4614-6438-9_101934-1.
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Takahashi, Mahoko Ueda, et So Nakagawa. « Transcription Factor Genes ». Dans Evolution of the Human Genome I, 241–63. Tokyo : Springer Japan, 2017. http://dx.doi.org/10.1007/978-4-431-56603-8_12.
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Akiyama, Taishin, Junwen Qin, Daisuke Ohshima et Jun-ichiro Inoue. « Identification of Transcription Factors Activated in Thymic Epithelial Cells During Embryonic Thymus Development ». Dans Transcription Factor Regulatory Networks, 163–70. New York, NY : Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-0805-9_13.
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Pinaire, Jane, Wan-Yin Chou, Mark Stewart, Katrina Dipple et David Crabb. « Activity of the Human Aldehyde Dehydrogenase 2 Promoter Is Influenced by the Balance between Activation by Hepatocyte Nuclear Factor 4 and Repression by Perosixome Proliferator Activated Receptor δ, Chicken Ovalbumin Upstream Promoter-Transcription Factor, and Apolipoprotein Regulatory Protein-1 ». Dans Advances in Experimental Medicine and Biology, 115–21. Boston, MA : Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4735-8_14.
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Wang, Ying-Jie, et Bo Kang. « OCT4 (Octamer-Binding Transcription Factor 4) ». Dans Encyclopedia of Signaling Molecules, 3643–50. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-67199-4_101982.
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Wang, Ying-Jie, et Bo Kang. « OCT4 (Octamer-Binding Transcription Factor 4) ». Dans Encyclopedia of Signaling Molecules, 1–7. New York, NY : Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4614-6438-9_101982-1.
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Corcoran, David B., David E. Thurston et Khondaker Miraz Rahman. « Chapter 4. Pyrrolobenzodiazepines as Transcription Factor Inhibitors : An Overview ». Dans Small-molecule Transcription Factor Inhibitors in Oncology, 81–124. Cambridge : Royal Society of Chemistry, 2018. http://dx.doi.org/10.1039/9781782624011-00081.
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Bartsch, Olaf, Ulrike Ziebold, Richard Marais, Karl-Heinz Klempnauer et Stefano Ferrari. « The Transcription Factor B-Myb is Phosphorylated and Activated by Cyclin A/Cdk2 ». Dans The Biology of Tumors, 31–41. Boston, MA : Springer US, 1998. http://dx.doi.org/10.1007/978-1-4899-1352-4_3.
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Ridker, Paul M., et Daniel T. Price. « Activated Protein C Resistance, Factor V Leiden, and Venous Thromboembolism ». Dans Pulmonary Embolism, 37–53. Tokyo : Springer Japan, 1999. http://dx.doi.org/10.1007/978-4-431-66893-0_3.
Texte intégralActes de conférences sur le sujet "Activated Transcription Factor 4"
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Mukherjee, Debarati, Heng Lu, Lin Yu, Satadru K. Lahiri, Tianshu Li et Jihe Zhao. « Abstract 1626 : Krüppel-like factor 8 activates the transcription of C-X-C cytokine receptor type 4 to promote breast cancer cell invasion, transendothelial migration and metastasis ». Dans Proceedings : AACR 107th Annual Meeting 2016 ; April 16-20, 2016 ; New Orleans, LA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.am2016-1626.
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Andreasen, P. A., A. Riccio, L. R. Lund, K. G. Welinder, F. Blasi et K. Danø. « PLASMINOGEN ACTIVATOR INHIBITOR TYPE 1 : STUDIES ON STRUCTURE AND REGULATION ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642810.
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Human plasminogen activator inhibitor type-1 is an Mr∼54,000 protein which specifically inhibits urokinase-type (u-PA) and tissue-type (t-PA) plasminogen activators. During inhibition, u-PA and t-PA convert PAI-1 to an inactive form with Mr∼50,000. We have determined the amino-terminal amino acid sequence of native and converted PAI-1, and isolated and partly sequenced PAI-1 cDNA. The data show that the conversion of PAI-1 consists of cleavage of an Arg-Met bond 33 residues from the carboxy-terminus, thus localizing the reactive center of the inhibitor to that position, and identifying PAI-1 as an "arg-serpin". PAI-1 activity is known to be influenced by a number of agents; we have studied the mechanisms of the stimulation of PAI-1 activity by transforming growth factor-β (TGF-β) and the synthetic glucocorticoid dexame-thasone in human WI-38 lung fibroblasts and HT-1080 fibrosarcoma cells. Bytheuse of PAI-1 cDNA, TGF-β was found to course a rapid increase in PAI-1 mRNA level in WI-38 cells, reaching a maximal 50-fold enhancement after 8 hours. Dexamethasone caused a 10-fold increase in PAI-1 mRNA in HT-1080 cells, which was detectable after 4 hours and became maximal after 16 hours. In both cases, the 3.4 as well as the 2.4 Kb-PAI-1-mRNA species were increased. Quantitative studies on the effect of these agents on PAI-1 protein levels in cell extracts and culture media by ELISA gave results consistent with the effects on PAI-1 mRNA. These studies suggest that TGF-β and glucocorticoids may exert important controls over plasminogen activation-mediated extracellular proteolysis through an enhancement of PAI-1 gene transcription.
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Fritz, Jason S., Anne Hamik et Mukesh Jain. « The Transcription Factor Krüppel-like Factor 4 (KLF4) Modulates Endothelial Permeability ». Dans American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a1038.
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Heo, Su-Jin, Tristan P. Driscoll et Robert L. Mauck. « Dynamic Tensile Loading Activates TGF and BMP Signaling in Mesenchymal Stem Cells on Aligned Nanofibrous Scaffolds ». Dans ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80706.
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Mesenchymal stem cells (MSCs) are a promising cell source for tissue engineering applications, given their ease of isolation and multi-potential differentiation capacity [1]. External mechanical cues directly influence MSC lineage commitment [2]. However, it is not yet clear how these physical cues are transduced to the cell nucleus, an understanding of which may prove essential for orthopaedic tissue engineering. Transforming growth factor beta (TGFβ) and bone morphogenetic protein (BMP), members of the TGF beta superfamily, regulate cellular processes including growth and differentiation [3, 4]. TGF and/or BMP ligand binding initiate SMAD phosphorylation, translocation to the nucleus, and transcriptional activation of target genes [4]. Additionally, both ligands can influence the organization of chromatin and the Lamin A/C (LMAC) nucleoskeletal network [5]. For example, we have recently shown that TGF-β3 leads to corticalized LMAC, marked increases in heterochromatin (HTC), and increased nuclear stiffness [6]. Interestingly, dynamic tensile stretch of MSCs on aligned nanofibrous scaffolds, in the absence of these differentiation factors, resulted in many of these same nuclear transformations [6, 7]. The objective of this study was to identify how dynamic tensile stress is transduced in MSCs on aligned nanofibrous scaffolds, and further, to ascertain whether these mechanoregulatory changes are coordinated through TGFβ/BMP signaling pathways.
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Koga, Hironori, Yasuko Imamura, Yu Ikezono, Fumitaka Wada, Toru Nakamura, Hideki Iwamoto, Atsutaka Masuda, Takahiko Sakaue, Hirohisa Yano et Takuji Torimura. « Abstract 4601 : Regulation of Hes1 expression by the Wnt transcription factor T-cell factor-4 ». Dans Proceedings : AACR 107th Annual Meeting 2016 ; April 16-20, 2016 ; New Orleans, LA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.am2016-4601.
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Bagheri-Yarmand, Rozita, Gilbert J. Cote et Robert F. Gagel. « Abstract 5262 : Activating transcription factor 4 regulates RET autophosphorylation and ubiquitin-dependent degradation ». Dans Proceedings : AACR Annual Meeting 2014 ; April 5-9, 2014 ; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-5262.
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Hu, Biao, Zhe Wu et Sem H. Phan. « Regulation Of Telomerase Reverse Transcriptase Gene Expression By Kruppel-Like Transcription Factor 4 ». Dans American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California. American Thoracic Society, 2012. http://dx.doi.org/10.1164/ajrccm-conference.2012.185.1_meetingabstracts.a3516.
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Zhao, Zhongming, et Jingchun Sun. « Abstract 4948 : Uncovering microRNA and transcription factor-mediated regulatory network in glioblastoma ». Dans Proceedings : AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012 ; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-4948.
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Hollenhorst, Peter C., Mary W. Ferris, Megan A. Hull, Heejoon Chae, Sun Kim et Barbara J. Graves. « Abstract 3090 : Oncogenic ETS transcription factors bind ETS/AP-1 sequences and activate a RAS/MAPK gene expression program in the absence of MAPK activation ». Dans Proceedings : AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012 ; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-3090.
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Hannemann, Nicole, Anne Schnelzer, Jutta Jordan, Martin Eberhardt, Ulrike Schleicher, Axel Hueber, Stephen Reid et al. « 01.12 Fra-1 transcription factor expression in macrophages foster inflammation during rheumatoid arthritis development ». Dans 37th European Workshop for Rheumatology Research 2–4 March 2017 Athens, Greece. BMJ Publishing Group Ltd and European League Against Rheumatism, 2017. http://dx.doi.org/10.1136/annrheumdis-2016-211048.12.
Texte intégralRapports d'organisations sur le sujet "Activated Transcription Factor 4"
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Fromm, Hillel, Paul Michael Hasegawa et Aaron Fait. Calcium-regulated Transcription Factors Mediating Carbon Metabolism in Response to Drought. United States Department of Agriculture, juin 2013. http://dx.doi.org/10.32747/2013.7699847.bard.
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Original objectives: The long-term goal of the proposed research is to elucidate the transcription factors, genes and metabolic networks involved in carbon metabolism and partitioning in response to water deficit. The proposed research focuses on the GTLcalcium/calmodulinbindingTFs and the gene and metabolic networks modulated by these TFs in Arabidopsis thaliana. The specific objectives are as follows. Objective-1 (USA): Physiological analyses of GTL1 loss- and gain-of-function plants under water sufficient and drought stress conditions Objective 2 (USA / Israel-TAU): Characterizion of GTL target genes and bioinformatic analysis of data to eulcidate gene-network topology. Objective-3 (Israel-TAU): Regulation of GTLmediated transcription by Ca²⁺/calmodulin: mechanism and biological significance. Objective-4 (Israel-BGU): Metabolic networks and carbon partitioning in response to drought. Additional direction: In the course of the project we added another direction, which was reported in the 2nd annual report, to elucidate genes controlling drought avoidance. The TAU team has isolated a few unhydrotropic (hyd) mutants and are in the process of mapping these mutations (of hyd13 and hyd15; see last year's report for a description of these mutants under salt stress) in the Arabidopsis genome by map-based cloning and deep sequencing. For this purpose, each hyd mutant was crossed with a wild type plant of the Landsberg ecotype, and at the F2 stage, 500-700 seedlings showing the unhydrotropic phenotype were collected separately and pooled DNA samples were subkected to the Illumina deep sequencing technology. Bioinformatics were used to identify the exact genomic positions of the mutations (based on a comparison of the genomic sequences of the two Arabidopsis thaliana ecotypes (Columbia and Landsberg). Background: To feed the 9 billion people or more, expected to live on Earth by the mid 21st century, the production of high-quality food must increase substantially. Based on a 2009 Declaration of the World Summit on Food Security, a target of 70% more global food production by the year 2050 was marked, an unprecedented food-production growth rate. Importantly, due to the larger areas of low-yielding land globally, low-yielding environments offer the greatest opportunity for substantial increases in global food production. Nowadays, 70% of the global available water is used by agriculture, and 40% of the world food is produced from irrigated soils. Therefore, much needs to be done towards improving the efficiency of water use by plants, accompanied by increased crop yield production under water-limiting conditions. Major conclusions, solutions and achievements: We established that AtGTL1 (Arabidopsis thaliana GT-2 LIKE1) is a focal determinant in water deficit (drought) signaling and tolerance, and water use efficiency (WUE). The GTL1 transcription factor is an upstream regulator of stomatal development as a transrepressor of AtSDD1, which encodes a subtilisin protease that activates a MAP kinase pathway that negatively regulates stomatal lineage and density. GTL1 binds to the core GT3 cis-element in the SDD1 promoter and transrepresses its expression under water-sufficient conditions. GTL1 loss-of-function mutants have reduced stomatal number and transpiration, and enhanced drought tolerance and WUE. In this case, higher WUE under water sufficient conditions occurs without reduction in absolute biomass accumulation or carbon assimilation, indicating that gtl1-mediated effects on stomatal conductance and transpiration do not substantially affect CO₂ uptake. These results are proof-of-concept that fine-tuned regulation of stomatal density can result in drought tolerance and higher WUE with maintenance of yield stability. Implications: Accomplishments during the IS-4243-09R project provide unique tools for continued discovery research to enhance plant drought tolerance and WUE.
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Funkenstein, Bruria, et Shaojun (Jim) Du. Interactions Between the GH-IGF axis and Myostatin in Regulating Muscle Growth in Sparus aurata. United States Department of Agriculture, mars 2009. http://dx.doi.org/10.32747/2009.7696530.bard.
Texte intégralRésumé :
Growth rate of cultured fish from hatching to commercial size is a major factor in the success of aquaculture. The normal stimulus for muscle growth in growing fish is not well understood and understanding the regulation of muscle growth in fish is of particular importance for aquaculture. Fish meat constitutes mostly of skeletal muscles and provides high value proteins in most people's diet. Unlike mammals, fish continue to grow throughout their lives, although the size fish attain, as adults, is species specific. Evidence indicates that muscle growth is regulated positively and negatively by a variety of growth and transcription factors that control both muscle cell proliferation and differentiation. In particular, growth hormone (GH), fibroblast growth factors (FGFs), insulin-like growth factors (IGFs) and transforming growth factor-13 (TGF-13) play critical roles in myogenesis during animal growth. An important advance in our understanding of muscle growth was provided by the recent discovery of the crucial functions of myostatin (MSTN) in controlling muscle growth. MSTN is a member of the TGF-13 superfamily and functions as a negative regulator of skeletal muscle growth in mammals. Studies in mammals also provided evidence for possible interactions between GH, IGFs, MSTN and the musclespecific transcription factor My oD with regards to muscle development and growth. The goal of our project was to try to clarify the role of MSTNs in Sparus aurata muscle growth and in particular determine the possible interaction between the GH-IGFaxis and MSTN in regulating muscle growth in fish. The steps to achieve this goal included: i) Determining possible relationship between changes in the expression of growth-related genes, MSTN and MyoD in muscle from slow and fast growing sea bream progeny of full-sib families and that of growth rate; ii) Testing the possible effect of over-expressing GH, IGF-I and IGF-Il on the expression of MSTN and MyoD in skeletal muscle both in vivo and in vitro; iii) Studying the regulation of the two S. aurata MSTN promoters and investigating the possible role of MyoD in this regulation. The major findings of our research can be summarized as follows: 1) Two MSTN promoters (saMSTN-1 and saMSTN-2) were isolated and characterized from S. aurata and were found to direct reporter gene activity in A204 cells. Studies were initiated to decipher the regulation of fish MSTN expression in vitro using the cloned promoters; 2) The gene coding for saMSTN-2 was cloned. Both the promoter and the first intron were found to be polymorphic. The first intron zygosity appears to be associated with growth rate; 3) Full length cDNA coding for S. aurata growth differentiation factor-l I (GDF-II), a closely related growth factor to MSTN, was cloned from S. aurata brain, and the mature peptide (C-terminal) was found to be highly conserved throughout evolution. GDF-II transcript was detected by RT -PCR analysis throughout development in S. aurata embryos and larvae, suggesting that this mRNA is the product of the embryonic genome. Transcripts for GDF-Il were detected by RT-PCR in brain, eye and spleen with highest level found in brain; 4) A novel member of the TGF-Bsuperfamily was partially cloned from S. aurata. It is highly homologous to an unidentified protein (TGF-B-like) from Tetraodon nigroviridisand is expressed in various tissues, including muscle; 5) Recombinant S. aurata GH was produced in bacteria, refolded and purified and was used in in vitro and in vivo experiments. Generally, the results of gene expression in response to GH administration in vivo depended on the nutritional state (starvation or feeding) and the time at which the fish were sacrificed after GH administration. In vitro, recombinantsaGH activated signal transduction in two fish cell lines: RTHI49 and SAFI; 6) A fibroblastic-like cell line from S. aurata (SAF-I) was characterized for its gene expression and was found to be a suitable experimental system for studies on GH-IGF and MSTN interactions; 7) The gene of the muscle-specific transcription factor Myogenin was cloned from S. aurata, its expression and promoter activity were characterized; 8) Three genes important to myofibrillogenesis were cloned from zebrafish: SmyDl, Hsp90al and skNAC. Our data suggests the existence of an interaction between the GH-IGFaxis and MSTN. This project yielded a great number of experimental tools, both DNA constructs and in vitro systems that will enable further studies on the regulation of MSTN expression and on the interactions between members of the GHIGFaxis and MSTN in regulating muscle growth in S. aurata.
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Eshed-Williams, Leor, et Daniel Zilberman. Genetic and cellular networks regulating cell fate at the shoot apical meristem. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7699862.bard.
Texte intégralRésumé :
The shoot apical meristem establishes plant architecture by continuously producing new lateral organs such as leaves, axillary meristems and flowers throughout the plant life cycle. This unique capacity is achieved by a group of self-renewing pluripotent stem cells that give rise to founder cells, which can differentiate into multiple cell and tissue types in response to environmental and developmental cues. Cell fate specification at the shoot apical meristem is programmed primarily by transcription factors acting in a complex gene regulatory network. In this project we proposed to provide significant understanding of meristem maintenance and cell fate specification by studying four transcription factors acting at the meristem. Our original aim was to identify the direct target genes of WUS, STM, KNAT6 and CNA transcription factor in a genome wide scale and the manner by which they regulate their targets. Our goal was to integrate this data into a regulatory model of cell fate specification in the SAM and to identify key genes within the model for further study. We have generated transgenic plants carrying the four TF with two different tags and preformed chromatin Immunoprecipitation (ChIP) assay to identify the TF direct target genes. Due to unforeseen obstacles we have been delayed in achieving this aim but hope to accomplish it soon. Using the GR inducible system, genetic approach and transcriptome analysis [mRNA-seq] we provided a new look at meristem activity and its regulation of morphogenesis and phyllotaxy and propose a coherent framework for the role of many factors acting in meristem development and maintenance. We provided evidence for 3 different mechanisms for the regulation of WUS expression, DNA methylation, a second receptor pathway - the ERECTA receptor and the CNA TF that negatively regulates WUS expression in its own domain, the Organizing Center. We found that once the WUS expression level surpasses a certain threshold it alters cell identity at the periphery of the inflorescence meristem from floral meristem to carpel fate [FM]. When WUS expression highly elevated in the FM, the meristem turn into indeterminate. We showed that WUS activate cytokinine, inhibit auxin response and represses the genes required for root identity fate and that gradual increase in WUCHEL activity leads to gradual meristem enlargement that affect phyllotaxis. We also propose a model in which the direction of WUS domain expansion laterally or upward affects meristem structure differently. We preformed mRNA-seq on meristems with different size and structure followed by k-means clustering and identified groups of genes that are expressed in specific domains at the meristem. We will integrate this data with the ChIP-seq of the 4 TF to add another layer to the genetic network regulating meristem activity.
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Droby, Samir, Michael Wisniewski, Ron Porat et Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, décembre 2012. http://dx.doi.org/10.32747/2012.7594390.bard.
Texte intégralRésumé :
To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
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Lers, Amnon, et Gan Susheng. Study of the regulatory mechanism involved in dark-induced Postharvest leaf senescence. United States Department of Agriculture, janvier 2009. http://dx.doi.org/10.32747/2009.7591734.bard.
Texte intégralRésumé :
Postharvest leaf senescence contributes to quality losses in flowers and leafy vegetables. The general goal of this research project was to investigate the regulatory mechanisms involved in dark-induced leaf senescence. The regulatory system involved in senescence induction and control is highly complex and possibly involves a network of senescence promoting pathways responsible for activation of the senescence-associated genes. Pathways involving different internal signals and environmental factors may have distinctive importance in different leaf senescence systems. Darkness is known to have a role in enhancement of postharvest leaf senescence and for getting an insight into its regulatory mechanism/s we have applied molecular genetics and functional genomics approaches. The original objectives were: 1. Identification of dark-induced SAGs in Arabidopsis using enhancer/promoter trap lines and microarray approaches; 2. Molecular and functional characterization of the identified genes by analyzing their expression and examining the phenotypes in related knockout mutant plants; 3. Initial studies of promoter sequences for selected early dark-induced SAGs. Since genomic studies of senescence, with emphasis on dark-induced senescence, were early-on published which included information on potential regulatory genes we decided to use this new information. This is instead of using the uncharacterized enhancer/promoter trap lines as originally planned. We have also focused on specific relevant genes identified in the two laboratories. Based on the available genomic analyses of leaf senescence 10 candidate genes hypothesized to have a regulatory role in dark-induced senescence were subjected to both expression as well as functional analyses. For most of these genes senescence-specific regulation was confirmed, however, functional analyses using knock-out mutants indicated no consequence to senescence progression. The transcription factor WARK75 was found to be specifically expressed during natural and dark-induced leaf senescence. Functional analysis demonstrated that in detached leaves senescence under darkness was significantly delayed while no phenotypic consequences could be observed on growth and development, including no effect on natural leaf senescence,. Thus, WARKY75 is suggested to have a role in dark-induced senescence, but not in natural senescence. Another regulatory gene identified to have a role in senescence is MKK9 encoding for a Mitogen-Activated Protein Kinase Kinase 9 which is upregulated during senescence in harvested leaves as well as in naturally senescing leaves. MKK9 can specifically phosphorylate another kinase, MPK6. Both knockouts of MKK9 and MPK6 displayed a significantly senescence delay in harvested leaves and possibly function as a phosphorelay that regulates senescence. To our knowledge, this is the first report that clearly demonstrates the involvement of a MAP kinase pathway in senescence. This research not only revealed a new signal transduction pathway, but more important provided significant insights into the regulatory mechanisms underlying senescence in harvested leaves. In an additional line of research we have employed the promoter of the senescence-induced BFN1 gene as a handle for identifying components of the regulatory mechanism. This gene was shown to be activated during darkinduced senescence of detached leaves, as well as natural senescence. This was shown by following protein accumulation and promoter activity which demonstrated that this promoter is activated during dark-induced senescence. Analysis of the promoter established that, at least some of the regulatory sequences reside in an 80 bps long fragment of the promoter. Overall, progress was made in identification of components with a role in dark-induced senescence in this project. Further studies should be done in order to better understand the function of these components and develop approaches for modulating the progress of senescence in crop plants for the benefit of agriculture.
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Barg, Rivka, Erich Grotewold et Yechiam Salts. Regulation of Tomato Fruit Development by Interacting MYB Proteins. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7592647.bard.
Texte intégralRésumé :
Background to the topic: Early tomato fruit development is executed via extensive cell divisions followed by cell expansion concomitantly with endoreduplication. The signals involved in activating the different modes of growth during fruit development are still inadequately understood. Addressing this developmental process, we identified SlFSM1 as a gene expressed specifically during the cell-division dependent stages of fruit development. SlFSM1 is the founder of a class of small plant specific proteins containing a divergent SANT/MYB domain (Barg et al 2005). Before initiating this project, we found that low ectopic over-expression (OEX) of SlFSM1 leads to a significant decrease in the final size of the cells in mature leaves and fruits, and the outer pericarp is substantially narrower, suggesting a role in determining cell size and shape. We also found the interacting partners of the Arabidopsis homologs of FSM1 (two, belonging to the same family), and cloned their tomato single homolog, which we named SlFSB1 (Fruit SANT/MYB–Binding1). SlFSB1 is a novel plant specific single MYB-like protein, which function was unknown. The present project aimed at elucidating the function and mode of action of these two single MYB proteins in regulating tomato fruit development. The specific objectives were: 1. Functional analysis of SlFSM1 and its interacting protein SlFSB1 in relation to fruit development. 2. Identification of the SlFSM1 and/or SlFSB1 cellular targets. The plan of work included: 1) Detailed phenotypic, histological and cellular analyses of plants ectopically expressing FSM1, and plants either ectopically over-expressing or silenced for FSB1. 2) Extensive SELEX analysis, which did not reveal any specific DNA target of SlFSM1 binding, hence the originally offered ChIP analysis was omitted. 3) Genome-wide transcriptional impact of gain- and loss- of SlFSM1 and SlFSB1 function by Affymetrix microarray analyses. This part is still in progress and therefore results are not reported, 4) Search for additional candidate partners of SlFSB1 revealed SlMYBI to be an alternative partner of FSB1, and 5) Study of the physical basis of the interaction between SlFSM1 and SlFSB1 and between FSB1 and MYBI. Major conclusions, solutions, achievements: We established that FSM1 negatively affects cell expansion, particularly of those cells with the highest potential to expand, such as the ones residing inner to the vascular bundles in the fruit pericarp. On the other hand, FSB1 which is expressed throughout fruit development acts as a positive regulator of cell expansion. It was also established that besides interacting with FSM1, FSB1 interacts also with the transcription factor MYBI, and that the formation of the FSB1-MYBI complex is competed by FSM1, which recognizes in FSB1 the same region as MYBI does. Based on these findings a model was developed explaining the role of this novel network of the three different MYB containing proteins FSM1/FSB1/MYBI in the control of tomato cell expansion, particularly during fruit development. In short, during early stages of fruit development (Phase II), the formation of the FSM1-FSB1 complex serves to restrict the expansion of the cells with the greatest expansion potential, those non-dividing cells residing in the inner mesocarp layers of the pericarp. Alternatively, during growth phase III, after transcription of FSM1 sharply declines, FSB1, possibly through complexing with the transcription factor MYBI serves as a positive regulator of the differential cell expansion which drives fruit enlargement during this phase. Additionally, a novel mechanism was revealed by which competing MYB-MYB interactions could participate in the control of gene expression. Implications, both scientific and agricultural: The demonstrated role of the FSM1/FSB1/MYBI complex in controlling differential cell growth in the developing tomato fruit highlights potential exploitations of these genes for improving fruit quality characteristics. Modulation of expression of these genes or their paralogs in other organs could serve to modify leaf and canopy architecture in various crops.
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Gal-On, Amit, Shou-Wei Ding, Victor P. Gaba et Harry S. Paris. role of RNA-dependent RNA polymerase 1 in plant virus defense. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7597919.bard.
Texte intégralRésumé :
Objectives: Our BARD proposal on the impact of RNA-dependent RNA polymerase 1 (RDR1) in plant defense against viruses was divided into four original objectives. 1. To examine whether a high level of dsRNA expression can stimulate RDR1 transcription independent of salicylic acid (SA) concentration. 2. To determine whether the high or low level of RDR1 transcript accumulation observed in virus resistant and susceptible cultivars is associated with viral resistance and susceptibility. 3. To define the biogenesis and function of RDR1-dependent endogenous siRNAs. 4. To understand why Cucumber mosaic virus (CMV) can overcome RDR1-dependent resistance. The objectives were slightly changed due to the unique finding that cucumber has four different RDR1 genes. Background to the topic: RDR1 is a key plant defense against viruses. RDR1 is induced by virus infection and produces viral and plant dsRNAs which are processed by DICERs to siRNAs. siRNAs guide specific viral and plant RNA cleavage or serve as primers for secondary amplification of viral-dsRNA by RDR. The proposal is based on our preliminary results that a. the association of siRNA and RDR1 accumulation with multiple virus resistance, and b. that virus infection induced the RDR1-dependent production of a new class of endogenous siRNAs. However, the precise mechanisms underlying RDR1 induction and siRNA biogenesis due to virus infection remain to be discovered in plants. Major conclusions, solutions and achievements: We found that in the cucurbit family (cucumber, melon, squash, watermelon) there are 3-4 RDR1 genes not documented in other plant families. This important finding required a change in the emphasis of our objectives. We characterized 4 RDR1s in cucumber and 3 in melon. We demonstrated that in cucumber RDR1b is apparently a new broad spectrum virus resistance gene, independent of SA. In melon RDR1b is truncated, and therefore is assumed to be the reason that melon is highly susceptible to many viruses. RDR1c is dramatically induced due to DNA and RNA virus infection, and inhibition of RDR1c expression led to increased virus accumulation which suggested its important on gene silencing/defense mechanism. We show that induction of antiviral RNAi in Arabidopsis is associated with production of a genetically distinct class of virus-activated siRNAs (vasiRNAs) by RNA dependent RNA polymerase-1 targeting hundreds of host genes for RNA silencing by Argonaute-2. Production of vasiRNAs is induced by viruses from two different super groups of RNA virus families, targeted for inhibition by CMV, and correlated with virus resistance independently of viral siRNAs. We propose that antiviral RNAi activate broad-spectrum antiviral activity via widespread silencing of host genes directed by vasiRNAs, in addition to specific antiviral defense Implications both scientific and agricultural: The RDR1b (resistance) gene can now be used as a transcription marker for broad virus resistance. The discovery of vasiRNAs expands the repertoire of siRNAs and suggests that the siRNA-processing activity of Dicer proteins may play a more important role in the regulation of plant and animal gene expression than is currently known. We assume that precise screening of the vasiRNA host targets will lead in the near future for identification of plant genes associate with virus diseases and perhaps other pathogens.
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Dubcovsky, Jorge, Tzion Fahima, Ann Blechl et Phillip San Miguel. Validation of a candidate gene for increased grain protein content in wheat. United States Department of Agriculture, janvier 2007. http://dx.doi.org/10.32747/2007.7695857.bard.
Texte intégralRésumé :
High Grain Protein Content (GPC) of wheat is important for improved nutritional value and industrial quality. However, selection for this trait is limited by our poor understanding of the genes involved in the accumulation of protein in the grain. A gene with a large effect on GPC was detected on the short arm of chromosome 6B in a Triticum turgidum ssp. dicoccoides accession from Israel (DIC, hereafter). During the previous BARD project we constructed a half-million clones Bacterial Artificial Chromosome (BAC) library of tetraploid wheat including the high GPC allele from DIC and mapped the GPC-B1 locus within a 0.3-cM interval. Our long-term goal is to provide a better understanding of the genes controlling grain protein content in wheat. The specific objectives of the current project were to: (1) complete the positional cloning of the GPC-B1 candidate gene; (2) characterize the allelic variation and (3) expression profile of the candidate gene; and (4) validate this gene by using a transgenic RNAi approach to reduce the GPC transcript levels. To achieve these goals we constructed a 245-kb physical map of the GPC-B1 region. Tetraploid and hexaploid wheat lines carrying this 245-kb DIC segment showed delayed senescence and increased GPC and grain micronutrients. The complete sequencing of this region revealed five genes. A high-resolution genetic map, based on approximately 9,000 gametes and new molecular markers enabled us to delimit the GPC-B1 locus to a 7.4-kb region. Complete linkage of the 7.4-kb region with earlier senescence and increase in GPC, Zn, and Fe concentrations in the grain suggested that GPC-B1 is a single gene with multiple pleiotropic effects. The annotation of this 7.4-kb region identified a single gene, encoding a NAC transcription factor, designated as NAM-B1. Allelic variation studies demonstrated that the ancestral wild wheat allele encodes a functional NAC transcription factor whereas modern wheat varieties carry a non-functional NAM-B1 allele. Quantitative PCR showed that transcript levels for the multiple NAMhomologues were low in flag leaves prior to anthesis, after which their levels increased significantly towards grain maturity. Reduction in RNA levels of the multiple NAMhomologues by RNA interference delayed senescence by over three weeks and reduced wheat grain protein, Zn, and Fe content by over 30%. In the transgenic RNAi plants, residual N, Zn and Fe in the dry leaves was significantly higher than in the control plants, confirming a more efficient nutrient remobilization in the presence of higher levels of GPC. The multiple pleiotropic effects of NAM genes suggest a central role for these genes as transcriptional regulators of multiple processes during leaf senescence, including nutrient remobilization to the developing grain. The cloning of GPC-B1 provides a direct link between the regulation of senescence and nutrient remobilization and an entry point to characterize the genes regulating these two processes. This may contribute to their more efficient manipulation in crops and translate into food with enhanced nutritional value. The characterization of the GPC-B1 gene will have a significant impact on wheat production in many regions of the world and will open the door for the identification of additional genes involved in the accumulation of protein in the grain.
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Prusky, Dov, Noel T. Keen et Stanley Freeman. Elicitation of Preformed Antifungal Compounds by Non-Pathogenic Fungus Mutants and their Use for the Prevention of Postharvest Decay in Avocado Fruits. United States Department of Agriculture, janvier 1996. http://dx.doi.org/10.32747/1996.7570573.bard.
Texte intégralRésumé :
C. gloeosporioides attacks unripe avocado fruits in the orchard. Germinated spores produce appressoria that germinate and breach the cuticle, but the resultant subcuticular hyphae become quiescent and do not develop further until fruit is harvested and ripens. Resistance of unripe avocado to attach by C. gloeosporioides is correlated with the presence of fungitoxic concentrations of the preformed antifungal compound, 1-acetoxy-2-hydroxy-4-oxoheneicosa-12, 15 diene in the pericarp of unripe fruits. The objective of this proposal was to study the signal transduction process by which elicitors induce resistance in avocado. It was found that abiotic elicitors, infection of avocado fruit with C. gloeosporioides or treatment of avocado cell suspension with cell-wall elicitor induced a significant production of reactive oxygen species (ROS). Ripe and unripe fruit tissue differ with regard to the ROS production. The unripe, resistant fruit are physiologically able to react and to produce high levels of ROS and increased activity of H+ATPase that can enhance the phenylpropanoid pathway ad regulate the levels of the antifungal compound-diene, inhibit fungal development, resulting in its quiescence. Interestingly, it was also found that growth regulators like cytokinin could do activation of the mechanism of resistance. Postharvest treatments of cytokinins strongly activated the phenylpropanoid pathway and induce resistance. We have developed non-pathogenic strains of C. gloeosporioides by Random Enzyme Mediated Integration and selected a hygromycin resistance, non-pathogenic strain Cg-142 out of 3500 transformants. This non-pathogenic isolate activates H+ATPase and induces resistance against Colletotrichum attack. As a basis for studying the importance of PL in pathogenicity, we have carried out heterologous expression of pel from C. gloeosporioides in the non-pathogenic C. magna and determine the significant increase in pathogenicity of the non-pathogenic strain. Based on these results we can state that pectate lyase is an important pathogenicity factor of C. gloeosporioides and found that fungal pathogenicity is affected not by pel but by PL secretion. Our results suggest that PH regulates the secretion of pectate lyase, and support its importance as a pathogenicity factor during the attack of avocado fruit by C. gloeosporioides . This implicates that if these findings are of universal importance in fungi, control of disease development could be done by regulation of secretion of pathogenicity factors.
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Lapidot, Moshe, et Vitaly Citovsky. molecular mechanism for the Tomato yellow leaf curl virus resistance at the ty-5 locus. United States Department of Agriculture, janvier 2016. http://dx.doi.org/10.32747/2016.7604274.bard.
Texte intégralRésumé :
Tomato yellow leaf curl virus (TYLCV) is a major pathogen of tomato that causes extensive crop loss worldwide, including the US and Israel. Genetic resistance in the host plant is considered highly effective in the defense against viral infection in the field. Thus, the best way to reduce yield losses due to TYLCV is by breeding tomatoes resistant or tolerant to the virus. To date, only six major TYLCV-resistance loci, termed Ty-1 to Ty-6, have been characterized and mapped to the tomato genome. Among tomato TYLCV-resistant lines containing these loci, we have identified a major recessive quantitative trait locus (QTL) that was mapped to chromosome 4 and designated ty-5. Recently, we identified the gene responsible for the TYLCV resistance at the ty-5 locus as the tomato homolog of the gene encoding messenger RNA surveillance factor Pelota (Pelo). A single amino acid change in the protein is responsible for the resistant phenotype. Pelo is known to participate in the ribosome-recycling phase of protein biosynthesis. Our hypothesis was that the resistant allele of Pelo is a “loss-of-function” mutant, and inhibits or slows-down ribosome recycling. This will negatively affect viral (as well as host-plant) protein synthesis, which may result in slower infection progression. Hence we have proposed the following research objectives: Aim 1: The effect of Pelota on translation of TYLCV proteins: The goal of this objective is to test the effect Pelota may or may not have upon translation of TYLCV proteins following infection of a resistant host. Aim 2: Identify and characterize Pelota cellular localization and interaction with TYLCV proteins: The goal of this objective is to characterize the cellular localization of both Pelota alleles, the TYLCV-resistant and the susceptible allele, to see whether this localization changes following TYLCV infection, and to find out which TYLCV protein interacts with Pelota. Our results demonstrate that upon TYLCV-infection the resistant allele of pelota has a negative effect on viral replication and RNA transcription. It is also shown that pelota interacts with the viral C1 protein, which is the only viral protein essential for TYLCV replication. Following subcellular localization of C1 and Pelota it was found that both protein localize to the same subcellular compartments. This research is innovative and potentially transformative because the role of Peloin plant virus resistance is novel, and understanding its mechanism will lay the foundation for designing new antiviral protection strategies that target translation of viral proteins. BARD Report - Project 4953 Page 2