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Добірка наукової літератури з теми "ATF6α"

Автор: Grafiati

Опубліковано: 7 грудня 2024

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Статті в журналах з теми "ATF6α"

Amyot, Julie, Isma Benterki, Ghislaine Fontés, Derek K. Hagman, Mourad Ferdaoussi, Tracy Teodoro, Allen Volchuk, Érik Joly, and Vincent Poitout. "Binding of activating transcription factor 6 to the A5/Core of the rat insulin II gene promoter does not mediate its transcriptional repression." Journal of Molecular Endocrinology 47, no. 3 (August 5, 2011): 273–83. http://dx.doi.org/10.1530/jme-11-0016.

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Pancreatic β-cells have a well-developed endoplasmic reticulum due to their highly specialized secretory function to produce insulin in response to glucose and nutrients. It has been previously reported that overexpression of activating transcription factor 6 (ATF6) reduces insulin gene expression in part via upregulation of small heterodimer partner. In this study, we investigated whether ATF6 directly binds to the insulin gene promoter, and whether its direct binding represses insulin gene promoter activity. A bioinformatics analysis identified a putative ATF6 binding site in the A5/Core region of the rat insulin II gene promoter. Direct binding of ATF6 was confirmed using several approaches. Electrophoretic mobility shift assays in nuclear extracts from MCF7 cells, isolated rat islets and insulin-secreting HIT-T15 cells showed ATF6 binding to the native A5/Core of the rat insulin II gene promoter. Antibody-mediated supershift analyses revealed the presence of both ATF6 isoforms, ATF6α and ATF6β, in the complex. Chromatin immunoprecipitation assays confirmed the binding of ATF6α and ATF6β to a region encompassing the A5/Core of the rat insulin II gene promoter in isolated rat islets. Overexpression of the active (cleaved) fragment of ATF6α, but not ATF6β, inhibited the activity of an insulin promoter–reporter by 50%. However, the inhibitory effect of ATF6α was insensitive to mutational inactivation or deletion of the A5/Core. Therefore, although ATF6 binds directly to the A5/Core of the rat insulin II gene promoter, this direct binding does not appear to contribute to its repressive activity.

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Yoshida, Hiderou, Tetsuya Okada, Kyosuke Haze, Hideki Yanagi, Takashi Yura, Manabu Negishi та Kazutoshi Mori. "Endoplasmic Reticulum Stress-Induced Formation of Transcription Factor Complex ERSF Including NF-Y (CBF) and Activating Transcription Factors 6α and 6β That Activates the Mammalian Unfolded Protein Response". Molecular and Cellular Biology 21, № 4 (15 лютого 2001): 1239–48. http://dx.doi.org/10.1128/mcb.21.4.1239-1248.2001.

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ABSTRACT The levels of molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) are controlled by a transcriptional induction process termed the unfolded protein response (UPR). The mammalian UPR is mediated by the cis-acting ER stress response element (ERSE), the consensus sequence of which is CCAAT-N9-CCACG. We recently proposed that ER stress response factor (ERSF) binding to ERSE is a heterologous protein complex consisting of the constitutive component NF-Y (CBF) binding to CCAAT and an inducible component binding to CCACG and identified the basic leucine zipper-type transcription factors ATF6α and ATF6β as inducible components of ERSF. ATF6α and ATF6β produced by ER stress-induced proteolysis bind to CCACG only when CCAAT is bound to NF-Y, a heterotrimer consisting of NF-YA, NF-YB, and NF-YC. Interestingly, the NF-Y and ATF6 binding sites must be separated by a spacer of 9 bp. We describe here the basis for this strict requirement by demonstrating that both ATF6α and ATF6β physically interact with NF-Y trimer via direct binding to the NF-YC subunit. ATF6α and ATF6β bind to the ERSE as a homo- or heterodimer. Furthermore, we showed that ERSF including NF-Y and ATF6α and/or β and capable of binding to ERSE is indeed formed when the cellular UPR is activated. We concluded that ATF6 homo- or heterodimers recognize and bind directly to both the DNA and adjacent protein NF-Y and that this complex formation process is essential for transcriptional induction of ER chaperones.

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Lee, Ann-Hwee, Neal N. Iwakoshi, and Laurie H. Glimcher. "XBP-1 Regulates a Subset of Endoplasmic Reticulum Resident Chaperone Genes in the Unfolded Protein Response." Molecular and Cellular Biology 23, no. 21 (November 1, 2003): 7448–59. http://dx.doi.org/10.1128/mcb.23.21.7448-7459.2003.

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ABSTRACT The mammalian unfolded protein response (UPR) protects the cell against the stress of misfolded proteins in the endoplasmic reticulum (ER). We have investigated here the contribution of the UPR transcription factors XBP-1, ATF6α, and ATF6β to UPR target gene expression. Gene profiling of cell lines lacking these factors yielded several XBP-1-dependent UPR target genes, all of which appear to act in the ER. These included the DnaJ/Hsp40-like genes, p58IPK, ERdj4, and HEDJ, as well as EDEM, protein disulfide isomerase-P5, and ribosome-associated membrane protein 4 (RAMP4), whereas expression of BiP was only modestly dependent on XBP-1. Surprisingly, given previous reports that enforced expression of ATF6α induced a subset of UPR target genes, cells deficient in ATF6α, ATF6β, or both had minimal defects in upregulating UPR target genes by gene profiling analysis, suggesting the presence of compensatory mechanism(s) for ATF6 in the UPR. Since cells lacking both XBP-1 and ATF6α had significantly impaired induction of select UPR target genes and ERSE reporter activation, XBP-1 and ATF6α may serve partially redundant functions. No UPR target genes that required ATF6β were identified, nor, in contrast to XBP-1 and ATF6α, did the activity of the UPRE or ERSE promoters require ATF6β, suggesting a minor role for it during the UPR. Collectively, these results suggest that the IRE1/XBP-1 pathway is required for efficient protein folding, maturation, and degradation in the ER and imply the existence of subsets of UPR target genes as defined by their dependence on XBP-1. Further, our observations suggest the existence of additional, as-yet-unknown, key regulators of the UPR.

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Ishikawa, Tokiro, Tetsuya Okada, Tomoko Ishikawa-Fujiwara, Takeshi Todo, Yasuhiro Kamei, Shuji Shigenobu, Minoru Tanaka та ін. "ATF6α/β-mediated adjustment of ER chaperone levels is essential for development of the notochord in medaka fish". Molecular Biology of the Cell 24, № 9 (травень 2013): 1387–95. http://dx.doi.org/10.1091/mbc.e12-11-0830.

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ATF6α and ATF6β are membrane-bound transcription factors activated by regulated intramembrane proteolysis in response to endoplasmic reticulum (ER) stress to induce various ER quality control proteins. ATF6α- and ATF6β single-knockout mice develop normally, but ATF6α/β double knockout causes embryonic lethality, the reason for which is unknown. Here we show in medaka fish that ATF6α is primarily responsible for transcriptional induction of the major ER chaperone BiP and that ATF6α/β double knockout, but not ATF6α- or ATF6β single knockout, causes embryonic lethality, as in mice. Analyses of ER stress reporters reveal that ER stress occurs physiologically during medaka early embryonic development, particularly in the brain, otic vesicle, and notochord, resulting in ATF6α- and ATF6β-mediated induction of BiP, and that knockdown of the α1 chain of type VIII collagen reduces such ER stress. The absence of transcriptional induction of several ER chaperones in ATF6α/β double knockout causes more profound ER stress and impaired notochord development, which is partially rescued by overexpression of BiP. Thus ATF6α/β-mediated adjustment of chaperone levels to increased demands in the ER is essential for development of the notochord, which synthesizes and secretes large amounts of extracellular matrix proteins to serve as the body axis before formation of the vertebra.

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Sharma, Rohit B., Christine Darko, and Laura C. Alonso. "Intersection of the ATF6 and XBP1 ER stress pathways in mouse islet cells." Journal of Biological Chemistry 295, no. 41 (August 11, 2020): 14164–77. http://dx.doi.org/10.1074/jbc.ra120.014173.

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Success or failure of pancreatic beta cell adaptation to ER stress is a determinant of diabetes susceptibility. The ATF6 and IRE1/XBP1 pathways are separate ER stress-response effectors important to beta cell health and function. ATF6α. and XBP1 direct overlapping transcriptional responses in some cell types. However, the signaling dynamics and interdependence of ATF6α and XBP1 in pancreatic beta cells have not been explored. To assess pathway-specific signal onset, we performed timed exposures of primary mouse islet cells to ER stressors and measured the early transcriptional response. Comparing the time course of induction of ATF6 and XBP1 targets suggested that the two pathways have similar response dynamics. The role of ATF6α in target induction was assessed by acute knockdown using islet cells from Atf6αflox/flox mice transduced with adenovirus expressing Cre recombinase. Surprisingly, given the mild impact of chronic deletion in mice, acute ATF6α knockdown markedly reduced ATF6-pathway target gene expression under both basal and stressed conditions. Intriguingly, although ATF6α knockdown did not alter Xbp1 splicing dynamics or intensity, it did reduce induction of XBP1 targets. Inhibition of Xbp1 splicing did not decrease induction of ATF6α targets. Taken together, these data suggest that the XBP1 and ATF6 pathways are simultaneously activated in islet cells in response to acute stress and that ATF6α is required for full activation of XBP1 targets, but XBP1 is not required for activation of ATF6α targets. These observations improve understanding of the ER stress transcriptional response in pancreatic islets.

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Teodoro, Tracy, Tanya Odisho, Elena Sidorova та Allen Volchuk. "Pancreatic β-cells depend on basal expression of active ATF6α-p50 for cell survival even under nonstress conditions". American Journal of Physiology-Cell Physiology 302, № 7 (1 квітня 2012): C992—C1003. http://dx.doi.org/10.1152/ajpcell.00160.2011.

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Activating transcription factor 6 (ATF6) is one of three principle endoplasmic reticulum (ER) stress response proteins and becomes activated when ER homeostasis is perturbed. ATF6 functions to increase ER capacity by stimulating transcription of ER-resident chaperone genes such as GRP78. Using an antibody that recognizes active ATF6α-p50, we found that active ATF6α was detected in insulinoma cells and rodent islets even under basal conditions and the levels were further increased by ER stress. To examine the function of ATF6α-p50, we depleted endogenous ATF6α-p50 levels using small interfering RNA in insulinoma cells. Knockdown of endogenous ATF6α-p50 levels by ∼60% resulted in a reduction in the steady-state levels of GRP78 mRNA and protein levels in nonstressed cells. Furthermore, ATF6α knockdown resulted in an apoptotic phenotype. We hypothesized that removal of the ATF6α branch of the unfolded protein response (UPR) would result in ER stress. However, neither the PKR-like endoplasmic reticulum kinase (PERK), nor the inositol requiring enzyme 1 (IRE1) pathways of the UPR were significantly activated in ATF6α knockdown cells, although these cells were more sensitive to ER stress-inducing compounds. Interestingly, phosphorylation of JNK, p38, and c-Jun were elevated in ATF6α knockdown cells and inhibition of JNK or p38 kinases prevented apoptosis. These results suggest that ATF6α may have a role in maintaining β-cell survival even in the absence of ER stress.

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Xue, Fei, Jianwen Lu, Samuel C. Buchl, Liankang Sun, Vijay H. Shah, Harmeet Malhi та Jessica L. Maiers. "Coordinated signaling of activating transcription factor 6α and inositol-requiring enzyme 1α regulates hepatic stellate cell-mediated fibrogenesis in mice". American Journal of Physiology-Gastrointestinal and Liver Physiology 320, № 5 (1 травня 2021): G864—G879. http://dx.doi.org/10.1152/ajpgi.00453.2020.

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ATF6α is a critical driver of hepatic stellate cell (HSC) activation in vitro. HSC-specific deletion of Atf6a limits fibrogenesis in vivo despite increased IRE1α signaling. Conditional deletion of Ire1α from HSCs limits fibrogenic gene transcription without impacting overall fibrosis. This could be due in part to observed upregulation of the ATF6α pathway. Dual loss of Atf6a and Ire1a from HSCs worsens fibrosis in vivo through enhanced HSC activation.

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Stauffer, Winston T., Adrian Arrieta, Erik A. Blackwood та Christopher C. Glembotski. "Sledgehammer to Scalpel: Broad Challenges to the Heart and Other Tissues Yield Specific Cellular Responses via Transcriptional Regulation of the ER-Stress Master Regulator ATF6α". International Journal of Molecular Sciences 21, № 3 (8 лютого 2020): 1134. http://dx.doi.org/10.3390/ijms21031134.

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Анотація:

There are more than 2000 transcription factors in eukaryotes, many of which are subject to complex mechanisms fine-tuning their activity and their transcriptional programs to meet the vast array of conditions under which cells must adapt to thrive and survive. For example, conditions that impair protein folding in the endoplasmic reticulum (ER), sometimes called ER stress, elicit the relocation of the ER-transmembrane protein, activating transcription factor 6α (ATF6α), to the Golgi, where it is proteolytically cleaved. This generates a fragment of ATF6α that translocates to the nucleus, where it regulates numerous genes that restore ER protein-folding capacity but is degraded soon after. Thus, upon ER stress, ATF6α is converted from a stable, transmembrane protein, to a rapidly degraded, nuclear protein that is a potent transcription factor. This review focuses on the molecular mechanisms governing ATF6α location, activity, and stability, as well as the transcriptional programs ATF6α regulates, whether canonical genes that restore ER protein-folding or unexpected, non-canonical genes affecting cellular functions beyond the ER. Moreover, we will review fascinating roles for an ATF6α isoform, ATF6β, which has a similar mode of activation but, unlike ATF6α, is a long-lived, weak transcription factor that may moderate the genetic effects of ATF6α.

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Azuma, Yoshinori, Daisuke Hagiwara, Wenjun Lu, Yoshiaki Morishita, Hidetaka Suga, Motomitsu Goto, Ryoichi Banno та ін. "Activating Transcription Factor 6α Is Required for the Vasopressin Neuron System to Maintain Water Balance Under Dehydration in Male Mice". Endocrinology 155, № 12 (1 грудня 2014): 4905–14. http://dx.doi.org/10.1210/en.2014-1522.

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Анотація:

Activating transcription factor 6α (ATF6α) is a sensor of endoplasmic reticulum (ER) stress and increases the expression of ER chaperones and molecules related to the ER-associated degradation of unfolded/misfolded proteins. In this study, we used ATF6α knockout (ATF6α−/−) mice to clarify the role of ATF6α in the arginine vasopressin (AVP) neuron system. Although urine volumes were not different between ATF6α−/− and wild-type (ATF6α+/+) mice with access to water ad libitum, they were increased in ATF6α−/− mice compared with those in ATF6α+/+ mice under intermittent water deprivation (WD) and accompanied by less urine AVP in ATF6α−/− mice. The mRNA expression of immunoglobulin heavy chain binding protein, an ER chaperone, was significantly increased in the supraoptic nucleus in ATF6α+/+ but not ATF6α−/− mice after WD. Electron microscopic analyses demonstrated that the ER lumen of AVP neurons was more dilated in ATF6α−/− mice than in ATF6α+/+ mice after WD. ATF6α−/− mice that were mated with mice possessing a mutation causing familial neurohypophysial diabetes insipidus (FNDI), which is characterized by progressive polyuria and AVP neuronal loss due to the accumulation of mutant AVP precursor in the ER, manifested increased urine volume under intermittent WD. The aggregate formation in the ER of AVP neurons was further impaired in FNDI/ATF6α−/− mice compared with that in FNDI mice, and AVP neuronal loss was accelerated in FNDI/ATF6α−/− mice under WD. These data suggest that ATF6α is required for the AVP neuron system to maintain water balance under dehydration.

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Pagliara, Valentina, Giuseppina Amodio, Vincenzo Vestuto, Silvia Franceschelli, Nicola Antonino Russo, Vittorio Cirillo, Giovanna Mottola, Paolo Remondelli та Ornella Moltedo. "Myogenesis in C2C12 Cells Requires Phosphorylation of ATF6α by p38 MAPK". Biomedicines 11, № 5 (16 травня 2023): 1457. http://dx.doi.org/10.3390/biomedicines11051457.

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Activating transcription factor 6α (ATF6α) is an endoplasmic reticulum protein known to participate in unfolded protein response (UPR) during ER stress in mammals. Herein, we show that in mouse C2C12 myoblasts induced to differentiate, ATF6α is the only pathway of the UPR activated. ATF6α stimulation is p38 MAPK-dependent, as revealed by the use of the inhibitor SB203580, which halts myotube formation and, at the same time, impairs trafficking of ATF6α, which accumulates at the cis-Golgi without being processed in the p50 transcriptional active form. To further evaluate the role of ATF6α, we knocked out the ATF6α gene, thus inhibiting the C2C12 myoblast from undergoing myogenesis, and this occurred independently from p38 MAPK activity. The expression of exogenous ATF6α in knocked-out ATF6α cells recover myogenesis, whereas the expression of an ATF6α mutant in the p38 MAPK phosphorylation site (T166) was not able to regain myogenesis. Genetic ablation of ATF6α also prevents the exit from the cell cycle, which is essential for muscle differentiation. Furthermore, when we inhibited differentiation by the use of dexamethasone in C2C12 cells, we found inactivation of p38 MAPK and, consequently, loss of ATF6α activity. All these findings suggest that the p-p38 MAPK/ATF6α axis, in pathophysiological conditions, regulates myogenesis by promoting the exit from the cell cycle, an essential step to start myoblasts differentiation.

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Більше джерел

Дисертації з теми "ATF6α"

Forouhan, Mitra. "The role of ATF6α and ATF6β in the UPR associated with an ER stress-induced skeletal chondrodysplasia". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/the-role-of-atf6alpha-and-atf6-in-the-upr-associated-with-an-er-stressinduced-skeletal-chondrodysplasia(9e26ce51-f188-454c-8ee1-3832845ee014).html.

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Mutations in the COL10A1 gene cause metaphyseal chondrodysplasia type Schmid (MCDS) by triggering ER stress and unfolded protein response (UPR). MCDS is characterised by a mild short-limb dwarfism accompanied by expansion of the cartilage growth plate hypertrophic zone (HZ) and altered differentiation of hypertrophic chondrocytes (HCs). ATF6 is one of the UPR mediators, which exists in two isoforms, ATF6α and ATF6β. Activation and up-regulation of ATF6α was a prominent biochemical sign of ER stress in a mouse model of MCDS, COL10a1 p.N617K. Although ATF6β is induced and activated in response to ER stress in a similar fashion to ATF6α, the role and significance of ATF6β in the pathology of many ER stress-associated diseases including MCDS is unknown. Here we utilized a combination of in vitro and in vivo approaches to define the precise role of each isoform of ATF6 in MCDS.To investigate the functions of ATF6α and ATF6β in vitro, we developed a MCDS cell model system (expressing either the wild type collagen X or one of the following MCDS-causing mutant forms of the protein: p.N617K, G618V, Y598D, and NC1del10) in which the expression of either ATF6α or ATF6β was efficiently silenced using siRNAs. ATF6α knockdown in HeLa cells expressing different MCDS-causing mutations suppressed the increased expression of UPR-associated genes such as BiP leading to an elevated ER stress, based on increased XBP1 splicing and/or ATF4 protein. In contrast, ATF6β knockdown did not significantly affect the mutant collagen X-induced increased expression of UPR-associated genes. Furthermore, the ER stress levels were significantly reduced in the ATF6β knockdown MCDS mutant cells based on the lower levels of XBP1 splicing and/or ATF4 protein detected. We then crossed the ATF6α/β knockout mice models with COL10a1 p.N617K mouse model of MCDS to investigate the function of ATF6α and ATF6β in vivo. Ablation of ATF6α in MCDS mice further- reduced the endochondral bone growth rate, further expanded the growth plate hypertrophic zone, and disrupted differentiation of HCs. Therefore, ATF6α appeared to play a chondroprotective role in MCDS as its deficiency caused an increase in the severity of the disease. Of particular note, the level of ER stress was further increased in the absence of ATF6α in MCDS, based on enhanced activities of PERK and IRE1 signalling pathways in compensation for the ATF6α loss. Paradoxically, ablation of ATF6β in MCDS mice reduced the intracellular retention of collagen X protein, and alleviated the ER stress as judged by the attenuated activities of PERK and IRE1 signalling pathways. The reduced ER stress resulting from deficiency for ATF6β in MCDS mice restored the expression of collagen X mRNA towards normal and improved the differentiation of HCs, causing a mark decrease in the expansion of HZ. The results presented within this thesis greatly increased our understanding of the function of ATF6α and ATF6β and their interplay in the pathogenesis of MCDS. We demonstrated an indispensable beneficiary role for ATF6α but a detrimental role for its closely related isoform, ATF6β, in pathology of MCDS. We also showed that the role of ATF6β should not be ignored. These findings may be used to develop a potential therapeutic strategy for MCDS through targeting and enhancing ATF6α-dependent and/or attenuating/blocking of ATF6β-dependent signalling pathways.

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Egawa, Naohiro. "The endoplasmic reticulum stress sensor, ATF6α, protects against neurotoxin-induced dopaminergic neuronal death". Kyoto University, 2011. http://hdl.handle.net/2433/142092.

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Giroud, Joëlle. "Impact of the UPR pathway on the establishment of the senescent phenotype induced by UVB." Electronic Thesis or Diss., Université de Lille (2022-....), 2024. http://www.theses.fr/2024ULILS036.

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Contexte : En France, la prévalence des modifications corporelles apparentes augmente, y compris chez les médecins généralistes. Il n’existe actuellement pas d’étude sur le vécu des médecins porteurs de modifications corporelles apparentes dans leur relation avec le patient.Méthode : Etude qualitative par IPA par entretiens semi-directifs entre janvier et juin 2024. Le recrutement a eu lieu au cours du CNGE de 2022, par « effet boule de neige » et via la diffusion d’annonces sur les réseaux sociaux. 6 médecins ont été interrogés sur la base d’un guide d’entretien révisé après chaque entretien.Résultats : Dans l’imaginaire collectif le look du médecin généraliste reste stéréotypé et est un moyen de se présenter à l’autre. Le médecin a tendance à s’auto-censurer dans son look pour se conformer à la norme sociale tout en ayant le désir d’être authentique. Les patients accueillent de façon bienveillante le plus souvent les modifications corporelles apparentes. Certains sont plus réticents mais les compétences professionnelles semblent primer sur la première impression. Les médecins s’amusent parfois des réactions des patients, d’autant plus s’ils assument pleinement leurs modifications corporelles. Pour d’autres, le bilan est plus mitigé, notamment lorsqu’un manque de légitimité se fait ressentir.Conclusion : En l’absence d’autre facteur de discrimination, les modifications corporelles apparentes du médecin généraliste sont plus ou moins acceptables selon leur visibilité et la sensibilité, la « norme » du patient. Il serait d’intérêt de réaliser d’autres études quant à l’impact des différents facteurs de discrimination du médecin sur la relation médecin-patient.Le vieillissement cutané, influencé par une combinaison de facteurs intrinsèques et extrinsèques, entraine des dommages capables d'altérer les fonctions cutanées. Parmi les facteurs extrinsèques, les rayonnements ultraviolets (UV) sont responsables du photo-vieillissement de la peau. Ces éléments conduisent notamment à une accumulation de cellules sénescentes capables de contribuer au développement de pathologies liées à l’âge, telles que les cancers cutanés. En effet, la sénescence s’accompagne de profonds changements morphologiques et moléculaires au sein de la cellule. Cela inclut notamment une modification de son sécrétome, qui s'enrichit en cytokines pro-inflammatoires, en facteurs de croissance et en enzymes remodelant la matrice extracellulaire, altérants les caractéristiques des tissus lors du vieillissement. Néanmoins, les mécanismes précis qui aboutissent au phénotype sénescent induit par les UVB restent largement inconnus. Dans ce contexte, l’objectif principal de ce travail a été d'identifier des mécanismes moléculaires sous-jacents à l’établissement de la sénescence induite par les UVB dans des fibroblastes de derme humains normaux (NHDFs), mécanismes qui pourraient contribuer au vieillissement cutané. In vitro, nous avons confirmé que des expositions répétées aux UVB induisent la sénescence prématurée des NHDFs et que cet état est associé à l’activation des trois branches de la voie UPR (Unfolded Protein Response) responsables du maintien de l’homéostasie du réticulum endoplasmique (RE), le premier compartiment de sécrétion. Ces observations ont été supportées par une analyse transcriptomique, révélant des éléments de régulation liés aux grandes voies de sénescence et aux fonctions du RE dans les NHDFs exposés aux UVB. Par la suite, nous avons montré que la branche ATF6α joue un rôle central dans la survenue des biomarqueurs du phénotype sénescent induit par les UVB. En effet, l’invalidation d’ATF6α protège non seulement des changements morphologiques induits par les UVB, mais réduit le pourcentage de cellules positives pour la SA-βgalactosidase (SA-βgal), prévient la persistance des dommages à l'ADN, et modifie l'expression de facteurs majeurs du phénotype sécrétoire associé à la sénescence (SASP) [...]
Skin ageing, influenced by a combination of intrinsic and extrinsic factors, can result in damage that has the potential to alter skin functions. Among extrinsic factors, ultraviolet (UV) radiation is responsible for skin photoageing. These factors notably contribute to the accumulation of senescent cells which in turn can contribute to the development of age-related pathologies, including skin cancers. Indeed, senescence is characterized by profound morphological and molecular changes within the cell. This includes a modification of its secretome, which becomes enriched in pro-inflammatory cytokines, growth factors, and matrix-remodelling enzymes, altering tissue characteristics during ageing. However, the exact mechanisms driving the senescent phenotype induced by UVB remain largely unknown. In this context, the main objective of this work was to identify the underlying molecular mechanisms responsible for the establishment of UVB-induced senescence in normal human dermal fibroblasts (NHDFs), mechanisms that may play a role in skin ageing. In vitro, we confirmed that repeated exposures to UVB induce premature senescence of NHDFs and that this state is associated with the activation of the three branches of the Unfolded Protein Response (UPR), which are responsible for maintaining endoplasmic reticulum (ER) homeostasis, the primary cellular secretion compartment. These observations were supported by transcriptomic analysis, revealing regulatory elements related to major senescence pathways and ER functions in UVB-exposed NHDFs. Subsequently, we demonstrated that the ATF6α branch plays a central role in the development of the UVB-induced senescent phenotype. Indeed, the silencing of ATF6α not only protects against morphological changes induced by UVB, but also reduces the percentage of senescence-associated β-galactosidase (SA-βgal) positive cells, prevents the persistence of DNA damage, and alters the expression of major factors associated with the senescence-associated secretory phenotype (SASP). The SASP, exerting a pro-tumoral action, led us to assess whether the conditioned medium (CM) from UVB-exposed fibroblasts invalidated for ATF6α could impact the migration and invasion potential of melanoma cells. However, we did not observe any ATF6α-dependent pro-migratory or pro-invasive effects. To highlight a potential role of ATF6α in another biological process, we further analyzed our transcriptomic and secretomic analyses and identified a possible effect of ATF6α on the paracrine control of the skin environment. To explore this, we focused on SASP factors (cytokines and metalloproteinases) regulated by ATF6α and whose impact on tissue environment was known. Subsequently, we treated a reconstructed human epidermis (RHE) model with CM from NHDFs exposed or not to UVB and invalidated or not for ATF6α.Surprisingly, we observed that the CM from UVB-exposed NHDFs increased the thickness of the RHE as well as the proliferation of basal keratinocytes, via an ATF6α-dependent mechanism. Finally, we identified IL-8 as a major paracrine factor involved in this process, as blocking IL-8 with neutralizing antibodies prevented excessive proliferation of keratinocytes. In conclusion, we report the role of ATF6α in UVB-induced senescence and its impact on the preservation of skin homeostasis under stress conditions, particularly through the regulation of the expression of SASP components. This suggests that ATF6α and its effectors could be promising targets for controlling the effects of skin ageing

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Felden, Julia Verfasser], and Bernd [Akademischer Betreuer] [Wissinger. "Die Bedeutung von Atf6 für die Zebrafischretina : Generierung und Charakterisierung eines atf6-/- - Zebrafischmodells / Julia Felden ; Betreuer: Bernd Wissinger." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1199929522/34.

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SICARI, DARIA. "Unveiling a role for mutant p53 in regulation of Unfolded Protein Response." Doctoral thesis, Università degli Studi di Trieste, 2018. http://hdl.handle.net/11368/2924770.

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Disturbances in the homeostasis of endoplasmic reticulum (ER) referred to as ER stress is involved in a variety of human diseases. Tumor progression is strictly related to ER stress, while cancer cells are prone to tolerate unfolded protein accumulation and to take advantages from ER stress-related pro-survival pathways. Mutation of Tp53 gene is a frequent event in human tumor and a significant factor in cancer development and progression. We report that cancer cells bearing mutant p53 respond to ER stress insult by dampening ER-stress associated pro-apoptotic factor and by sustaining survival. Mechanistically, we find that mutp53 is inhibiting JNK and CHOP and is promoting ATF6 transcriptional activity. These observations reveals a protective role of mutant p53 in the response to chronic ER stress, offering an additional perspective to cancer treatment. Indeed, we observed a cooperative effect in using mutp53 and ATF6 inhibitors in killing cancer cells.

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Santinelli, Raphaël. "Inhibition de la voie ATF6 de la réponse aux protéines mal formées comme nouvelle approche thérapeutique dans le cadre de la mucoviscidose." Electronic Thesis or Diss., Brest, 2024. http://www.theses.fr/2024BRES0009.

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La mucoviscidose est la maladie génétique létale à transmission autosomale récessive la plus fréquemment retrouvée dans la population européenne. Elle est due à des mutations altérant le gène CFTR, dont la plus fréquente est la mutation induisant la délétion d’une phénylalanine en position 508 de la séquence polypeptidique de cette protéine (p.Phe508del-CFTR). Ces mutations altèrent la viscosité du mucus présent à la surface apicale des cellules épithéliales des systèmes respiratoire, digestif et génital. Cela entraîne une baisse de la clairance mucociliaire, rendant difficile le renouvellement de ce mucus qui est la première barrière protectrice vis-à-vis du développement de microorganismes potentiellement pathogènes. En conséquence, des réponses inflammatoire et infectieuse se mettent en place. En ajoutant l’accumulation de protéines mal repliées dans la lumière du RE, le mécanisme de défense adaptatif UPR est déclenché. ATF6 fait partie de ses trois voies régulatrices. Il a été montré que ATF6 inhibait l’expression du CFTR. Le but de ce projet de thèse est d’évaluer les effets de l’inhibition de la S1P, une protéine centrale pour l’activation de ATF6, sur le p.Phe508del-CFTR par des moyens pharmacologiques. Les résultats montrent que les efflux d’ions Cl- lié à l’activité du canal p.Phe508del-CFTR était augmenté grâce à une augmentation de l’expression globale, ainsi que du transport de ce canal jusqu’à la membrane plasmique. Nous donnons également quelques pistes pouvant expliquer ces effets bénéfiques, notamment en rapport avec le déclenchement de l’UPS qui est une voie permettant le transport de protéines mutées jusqu’à la membrane plasmique
Cystic fibrosis is the most common lethal autosomal recessive genetic disease in the European population. It is caused by mutations in the CFTR gene, the most common of which is the deletion of a phenylalanine at position 508 of the protein's polypeptide sequence (p.Phe508del- CFTR). These mutations alter the viscosity of the mucus present on the apical surface of epithelial cells in the respiratory, digestive and genital systems. This leads to a reduction in mucociliary clearance, making it difficult to renew the mucus that forms the first protective barrier against the development of potentially pathogenic micro- organisms. As a result, inflammatory and infectious responses are triggered. By adding the accumulation of misfolded proteins in the lumen of the ER, the UPR adaptive defence mechanism is triggered. ATF6 is one of its three regulatory pathways. ATF6 has been shown to inhibit CFTR expression. The aim of this thesis project is to evaluate the effects of inhibiting S1P, a protein central for the activation of ATF6, on p.Phe508del-CFTR by pharmacological means. The results show that Cl- ion efflux linked to the activity of the p.Phe508del-CFTR channel is increased through an increase in the overall expression and transport of this channel to the plasma membrane. We also give some possible explanations for these beneficial effects, in particular in relation to the triggering of the UPS, a pathway that allows mutated proteins to be transported to the plasma membrane

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Huguet, Florentin. "Impact de la modulation de TRPM7 et ATF6 sur le cystic fibrosis transmembrane conductance regulator." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0058/document.

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La mucoviscidose est une maladie causée par des mutations du gène cftr entraînant des défauts importants de la protéine CFTR. La mutation la plus fréquente (F508del) est caractérisée par un repliement incorrect conduisant à la rétention de la protéine dans le RE.L’accumulation de CFTR-F508del dans le RE, l’inflammation et les infections vont déclencher un stress du RE dans les cellules épithéliales ainsi que l’UPR. Cette dernière est une réponse adaptative déclenchée par le stress du RE et permet de rétablir l’homéostasie de ce compartiment. L’UPR est constituée de trois voies majeures dont l’une d’entre elles est activée dans les cellules exprimant un CFTR-F508del. Il s’agit de la voie ATF6 qui est de plus responsable de la répression transcriptionnelle du CFTR, ce qui en fait une cible thérapeutique potentielle. Nous avons montré que son inhibition conduit à l’amélioration de la fonction duCFTR-F508del et à l’augmentation de sa présence à la membrane des cellules.Nous nous sommes également intéressés au Mg2+ et au TRPM7, le régulateur principal de la [Mg2+]i dans les cellules. Nous avons émis l’hypothèse que TRPM7 était en partie responsable de l’activation d’ATF6 dans les cellules exprimant un CFTR-F508del. Le but de cette seconde partie du projet était donc tout d’abord d’étudier la relation existante entre le Mg2+, TRPM7 et le CFTR. Nous avons montré qu’il existait des différences de [Mg2+]i selon le type de mutation du CFTR exprimé par les cellules. Ces différences sont en partie dues à un défaut d’activation de TRPM7, lui-même probablement lié à un défaut du CFTR. En augmentant l’activité de TRPM7 par du Naltriben, nous avons pu montrer un effet potentialisant sur leCFTR-G551D
Cystic fibrosis is caused by mutations in the cftr gene resulting in several defaults on the CFTR protein. The most frequent mutation is F508del which is characterized by an incorrect folding causing its retention within the ER. CFTR-F508del protein accumulation in the ER, inflammation and infections will trigger the ER stress in epithelial cells, as well as UPR. UPR constitutes an adaptive response of the ER in order to restore ER’s homeostasis. UPR consists in three major pathways. Among them, one is activated in cells expressing CFTR-F508del protein. The ATF6 pathway of UPR is responsible of the transcriptional repression of CFTR, which makes of it a potential therapeutic target. We showed that the inhibition of ATF6 leads to the improvement of CFTR-508del function, as well as its increased presence in the cellular membrane. We were also interested in Mg2+ and TRPM7, the main regulator of [Mg2+]i. We suspected that TRPM7 is, at least in part, responsible for the activation of ATF6 in cells expressing the mutant CFTR-F508del. Thus, the second part of my work was focused on the study of the relationship between Mg2+, TRPM7 and CFTR. We showed the existence of [Mg2+]I differences according to CFTR mutant expressed in cells. These differences are the result of an altered TRPM7 activation, probably in link with the mutated CFTR’s malfunction. We proved that increasing TRPM7 activity by Naltriben treatment potentiates CFTR-G551D

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Papaioannou, Alexandra. "Fine-tuning UPR signals and subsequent cellular outputs." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1B013.

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La présente thèse explore le monde de la biologie du stress du RE (réticulum endoplasmique). Une vue globale du RE et du stress du RE est d'abord fournie en commençant par les mécanismes de base impliqués pour aller vers de possibles applications cliniques. L'accent est ensuite mis sur le rôle crucial de l'UPR dans la cancérogénèse, qui est activée en réponse au stress du RE dans la micro-environnement de la tumeur. Après avoir passé en revue ces aspects, nous mettons en évidence des éléments manquants dans notre compréhension de la façon dont les signaux UPR sont affinés et conduisent soit à la restauration de l'homéostasie du RE et des cellules soit à la mort cellulaire. Parmi les branches de l'UPR, les signaux ATF6 et IRE1 deviennent notre sujet d'investigation en raison de leur convergence dans la régulation du facteur XBP1 favorisant la survie. D'une part, nous découvrons les mécanismes provenant du lumen du RE qui régulent l'activation de l'ATF6 en réponse au stress du RE et affectant la signalisation adaptative cellulaire de l'ATF6 en aval. D'autre part, nous observons l'existence d'un réseau autorégulateur de l'activité RNase de l’IRE1 consistant en un système tyrosine kinase-phosphatase ciblant la RtcB et impactant l'épissage de l'ARNm de XBP1. Ainsi, grâce à nos études, nous avons découvert un circuit de signalisation intégré capable d’ajuster avec précision les sorties cellulaires de l’activation conjointe ATF6 et IRE1 en réponse au stress du RE
The present thesis explores the world of ER (endoplasmic reticulum) stress biology. A global view of ER and ER stress is first provided with a transition from the basic mechanisms involved to possible clinical applications. The focus is then placed to the crucial role of the UPR in carcinogenesis that is activated in response to ER stress in the micro-environment of the tumor. After reviewing these aspects, we point to missing parts in our comprehension of how UPR signals are fine-tuned and lead to either restoration of ER and cell homeostasis or cell death. Among the UPR branches, ATF6 and IRE1 signaling become our focus of investigation because of their convergence in the regulation of the pro-survival factor XBP1s. On the one hand, we unravel mechanisms originating from the ER lumen that regulate the ATF6 activation in response to ER stress and affect its downstream cell adaptive signaling. On the other hand, we witness the existence of an auto-regulatory network of IRE1 RNase activity consisted of a tyrosine kinase-phosphatase system that targets RtcB and impacts on XBP1 mRNA splicing. Hence, through our studies we uncover an integrated signaling circuit that can fine-tune the cellular outputs of the joint ATF6 and IRE1 activation in response to ER stress

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Martindale, Joshua J. "Protecting the myocardium from ischemia and reperfusion injury via inducible activation of ATF6 or constitutive expression of MKK6 /." Diss., Connect to a 24 p. preview or request complete full text in PDF formate. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3236641.

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Lyle, Chimera. "Super Low Dose Endotoxin Exacerbates Low Grade Inflammation through Modulating Cell Stress and Decreasing Cellular Homeostatic Protein Expression." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/86360.

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The establishment of non-resolving inflammation underlies the pathogenesis of chronic inflammatory diseases in humans. Super low dose (SLD) endotoxin has been associated with exacerbating inflammation and the pathogenesis of chronic inflammatory diseases. However, the underlying molecular mechanisms are not well studied. In this study, I tested the hypothesis that SLD endotoxin may potentiate non-resolving innate immune cell inflammation through disrupting cellular endoplasmic reticulum (ER) homeostasis. We chose to study the dynamics of ER homeostasis in macrophages stimulated with SLD endotoxin. In naïve cells, ER stressor such as tunicamycin (TM) not only will induce cellular stress and inflammation through JNK and NFkβ activation, but also will cause subsequent compensatory homeostasis through inducing homeostatic molecules such as XBP1 and GRP78/BiP. We observed that cells challenged with SLD endotoxin have significantly reduced expression of homeostatic molecules XBP1 and BiP. Mechanistically, we observed that SLD-LPS increases phosphorylated HCK expression in TM treated cells. Phosphorylated HCK activation resulted in the phosphorylation of Golgi protein GRASP, leading to unstacking of Golgi cisterna and overall dysfunction of the Golgi apparatus. Dysfunctional Golgi apparatus and its effect on protein transport and secretion, may account for decreased levels of Site 2 Protease, reduced generation of ATF6 and its transcriptional target BiP. Taken together, our study reveal that super low dose endotoxin exacerbates low grade inflammation through increasing phosphorylation of HCK, inducing Golgi dysfunction, and decreasing BiP /homeostatic protein expression in innate immune cells.
Ph. D.

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Частини книг з теми "ATF6α"

Chiang, Wei-Chieh Jerry, Heike Kroeger, Lulu Chea, and Jonathan H. Lin. "Pathomechanisms of ATF6-Associated Cone Photoreceptor Diseases." In Retinal Degenerative Diseases, 305–10. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27378-1_50.

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Jerry Chiang, Wei-Chieh, and Jonathan H. Lin. "The Effects of IRE1, ATF6, and PERK Signaling on adRP-Linked Rhodopsins." In Retinal Degenerative Diseases, 661–67. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4614-3209-8_83.

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"ATF6." In Encyclopedia of Cancer, 299. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-16483-5_430.

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Тези доповідей конференцій з теми "ATF6α"

Mekhael, O., H. Patel, J. Imani, E. Ayaub, M. Padwal, A. Ayoub, M. Vierhout та ін. "Assessing the Role of ATF6α in the Alternative Activation of Macrophages in the Progression of Fibrotic Lung Diseases". У American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a7232.

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Edmondson, Jacob L., Megan R. Reed, Daniel Fil, Billie Heflin, Nathan Avaritt, Katherine Wallis, Alan J. Tackett, and Brian Koss. "538 ATF6 activation in melanoma promotes anti-tumor immunity and improves ICB therapy response." In SITC 39th Annual Meeting (SITC 2024) Abstracts, A610. BMJ Publishing Group Ltd, 2024. http://dx.doi.org/10.1136/jitc-2024-sitc2024.0538.

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McMellen, Alexandra N., and Benjamin G. Bitler. "Abstract A51: The role of ATF6-mediate AP-1 signaling in promoting PARP inhibitor-resistant ovarian cancer." In Abstracts: AACR Special Conference on Advances in Ovarian Cancer Research; September 13-16, 2019; Atlanta, GA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1557-3265.ovca19-a51.

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Yan, Xiao Hong, Yuan Wang, Ya Lan Ding, Min Hu, Gui Mei Wang, and Xiao Min Guo. "ATF6 activated endoplasmic reticulum stress involved in cardioprotection of hydrogen sulfide postconditioning against cardiac myocytes apoptosis by ischemia reperfusion in vivo." In Annual International Conference on Advanced Research: Physiology. Global Science & Technology Forum (GSTF), 2014. http://dx.doi.org/10.5176/2382-607x_arp14.16.

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Carvajal, Patricia, Sergio Aguilera, María-José Barrera, Carolina Lagos, Isabel Castro, Sergio González, Daniela Jara, Claudio Molina, and María-Julieta González. "THU0203 PROMOTER DNA METHYLATION AND HSA-MIR-424-5P REGULATE ATF6 ALPHA EXPRESSION IN SALIVARY GLANDS OF PATIENTS WITH SJÖGREN’S SYNDROME." In Annual European Congress of Rheumatology, EULAR 2019, Madrid, 12–15 June 2019. BMJ Publishing Group Ltd and European League Against Rheumatism, 2019. http://dx.doi.org/10.1136/annrheumdis-2019-eular.4712.

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Guan, Min. "Abstract 2653: Nelfinavir induces apoptosis in hormone-resistant prostate cancer cells through inhibition of regulated intramembrane proteolysis of SREBP-1 and ATF6." In Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.am2011-2653.

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