Activation of XBP1 but not ATF6α rescues heart failure induced by persistent ER stress in medaka fish
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ABSTRACT:
ORGANISM(S): Oryzias latipes
PROVIDER: GSE215040 | GEO | 2022/10/14
REPOSITORIES: GEO
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Project description:The unfolded protein response is triggered in vertebrates by ubiquitously expressed IRE1α/β (although IRE1β is gut-specific in mice), PERK, and ATF6α/β, transmembrane-type sensor proteins in the ER, to cope with ER stress, the accumulation of unfolded and misfolded proteins in the ER. Here, we burdened medaka fish, a vertebrate model organism, with ER stress persistently from fertilization by knocking out the AXER gene encoding an ATP/ADP exchanger in the ER membrane, leading to decreased ATP concentration-mediated impairment of the activity of Hsp70- and Hsp90-type molecular chaperones in the ER lumen. ER stress and apoptosis were evoked from 4 and 6 dpf, respectively, leading to the death of all AXER-KO medaka by 12 dpf because of heart failure (medaka hatch at 7 dpf). Importantly, constitutive activation of IRE1α signaling-but not ATF6α signaling-rescued this heart failure and allowed AXER-KO medaka to survive 3 d longer, likely because of XBP1-mediated transcriptional induction of ER-associated degradation components. Thus, activation of a specific pathway of the unfolded protein response can cure defects in a particular organ.
| S-EPMC10172766 | biostudies-literature
Project description:Activation of XBP1 but not ATF6α rescues heart failure induced by persistent ER stress in medaka fish
| PRJNA888120 | ENA
Project description:The IRE1α-XBP1 arm of the unfolded protein response (UPR) maintains endoplasmic reticulum (ER) homeostasis, but also controls UPR-independent processes such as cytokine production and lipid metabolism. Yet, the physiological consequences of IRE1α-XBP1 activation in immune cells remain largely unexplored. Here, we report that leukocyte-intrinsic IRE1α-XBP1 signaling drives prostaglandin biosynthesis and pain. Transcriptomic analyses revealed that induction of prostaglandin-endoperoxide synthase 2 (Ptgs2/Cox-2) and prostaglandin E synthase (Ptges/mPGES-1) was compromised in IRE1α-deficient myeloid cells undergoing ER stress or stimulated via pattern recognition receptors. Inducible biosynthesis of prostaglandins, including PGE2, was markedly decreased in myeloid cells lacking IRE1α or XBP1, but not altered in the absence of the two other ER stress sensors PERK and ATF6. Mechanistically, IRE1α-activated XBP1 bound to and directly induced the expression of human PTGS2 and PTGES to enable PGE2 generation. Mice selectively lacking IRE1α-XBP1 in leukocytes, or treated with pharmacological IRE1α inhibitors, failed to induce PGE2 upon challenge with inflammatory stimuli and demonstrated reduced behavioral pain responses in PGE2-dependent models of pain. Our study uncovers an unexpected role for IRE1α-XBP1 as a key mediator of prostaglandin biosynthesis and indicates that targeting this pathway may represent an alternative approach to control pain.
2020-05-16 | GSE131404 | GEO
Project description:IRE1a and XBP1 are key regulators of the unfolded protein response (UPR). XBP1 ablation causes profound hypolipidemia in mice, and triggers feedback activation of its upstream enzyme IRE1a, instigating regulated IRE1-dependent decay (RIDD), an mRNA degradation mechanism dependent on IRE1a's endoribonuclease activity. Comprehensive microarray analysis of XBP1 and/or IRE1a deficient liver identified genes involved in lipogenesis and lipoprotein metabolism as RIDD substrates, which might contribute to the suppression of plasma lipid levels by activated IRE1a. To identify RIDD substrate mRNAs and direct XBP1 targets in the liver, we performed a comprehensive comparative microarray analysis of three groups of RNA samples: WT and XBP1 deficient mice, WT and IRE1a deficient mice untreated or injected with tunicamycin, and XBP1 deficient mice injected with luciferase or IRE1a siRNA.
2012-10-17 | E-GEOD-40515 | biostudies-arrayexpress
Project description:The significant changes of hematopoietic cells induced by Xbp1S expression indicate that there is global alteration in gene expression. UPR induces transcription of Xbp1, and phosphorylation of the ER transmembrane kinase IRE1 initiates UPR-mediated mRNA splicing of Xbp1, resulting in the production of Xbp1S, an active form of a basic leucine zipper transcription factor. In the present study, Xbp1S retrovirus vector infected 32cl3 cells show cell cycle arrest and myeloid differentiation. Xbp1S may modulate important genes of differentiation and the cell cycle. RNA samples extracted from 32Dcl3 cells with pMIG (empty vector), pMY-Xbp1U (unspliced form) and pMY-Xbp1S (spliced form) retroviral vector transfected cells were subjected to expression profiling using the Affymetrix GeneChip microarray system.
2010-10-01 | E-GEOD-17023 | biostudies-arrayexpress
Project description:Partial hepatectomy (PH) imposes increased protein synthesis demands on remaining hepatocytes. Activation of IRE1α, a key sensor of endoplasmic reticulum (ER) stress, elicits XBP1 mRNA splicing and production of XBP1 protein, a main trigger of the unfolded protein response (UPR). Using genome-wide ChIPseq analysis we have explored the role of XBP1 during liver regeneration. XBP1 was induced in liver at 6h after PH in an IL-6 dependent manner. After PH, XBP1 silencing caused persistent ER stress, defective acute phase response (APR), increased hepatocellular damage and regenerative delay. At 6h post-PH, XBP1 bound an increased number of genes implicated in proteostasis, APR, metabolism, antioxidant defense and DNA damage response (DDR). ). XBP1 was linked to regulatory sequences containing canonical UPR motifs as well as motifs characteristic of other nuclear factors suggesting molecular interactions during liver regeneration. Upon PH, XBP1 bound the promoter of STAT3, a molecule downregulated in XBP1-silenced livers. XBP1 was indispensable for ser727-STAT3 phosphorylation, a post-translational modification implicated in cell proliferation and DNA damage repair. During active DNA replication XBP1 deficient livers showed high levels of the DNA double-strand break marker γ-H2AX, in association with defective upregulation of Eme1 and Fen1, two main executors of DDR. In conclusion, XBP1 is induced after PH and co-regulates UPR, APR and DDR during liver regeneration.
2017-01-17 | GSE86048 | GEO
Project description:The significant changes of hematopoietic cells induced by Xbp1S expression indicate that there is global alteration in gene expression. UPR induces transcription of Xbp1, and phosphorylation of the ER transmembrane kinase IRE1 initiates UPR-mediated mRNA splicing of Xbp1, resulting in the production of Xbp1S, an active form of a basic leucine zipper transcription factor. In the present study, Xbp1S retrovirus vector infected 32cl3 cells show cell cycle arrest and myeloid differentiation. Xbp1S may modulate important genes of differentiation and the cell cycle.
2010-10-01 | GSE17023 | GEO
Project description:BACKGROUND AND AIM: We previously established that endoplasmic reticulum stress leads to unfolded protein response (UPR) that promotes liver fibrosis by activating hepatic stellate cell (HSC). We aimed to determine the role of X-box binding protein 1 (XBP1), one of three UPR effector pathways, in the fibrogenic HSC activation. METHODS: XBP1 expression was measured by qPCR in tunicamycin-treated human HSC lines (TWNT4 and LX2) and culture-activated human primary HSCs. XBP1 was overexpressed in primary human HSCs and the HSC lines, and fibrogenic genes (COL1A1, ACTA2, PDGFRB, MMP2, TIMP1) and encoded proteins were assessed by qPCR and Western blotting, respectively. Autophagy was inhibited by knockdown of ATG7. Genome-wide transcriptome profiling was performed to determine modulated molecular pathway by XBP1. In vivo XBP1 activation was assessed in transcriptome datasets of fibrotic mouse models and immunohistochemistry of human liver tissues. RESULTS: XBP1 overexpression accompanied both tunicamycin- and culture-based HSC activation. Ectopic overexpression of XBP1 induced fibrogenic gene expression in the HSC lines, which was inhibited by knockdown of ATG7. UPR pathway together with PDGFRB pathway, a hallmark of HSC activation, were induced in transcriptome profiles of XBP1-transduced HSC lines. Some known fibrogenic pathways such as transforming growth factor (TGF)-beta pathway were not induced, suggesting partial contribution of XBP1 to the entire fibrogenic HSC activation machinery. XBP1 target gene signature defined in our XBP1-overexpressing HSC lines was significantly induced in liver tissue transcriptome profiles of carbon tetrachloride-treated or bile duct-ligated mouse models, and XBP1 and alpha-smooth muscle actin (encoded by ACTA2, another hallmark of HSC activation) were co-localized in human fibrotic liver tissues, collectively supporting involvement of XBP1 in HSC activation and fibrogesis in vivo. CONCLUSIONS: XBP1-mediated UPR is at least partially responsible for fibrogenic HSC activation via autophagy.
2016-12-21 | GSE78070 | GEO
Project description:IRE1a and XBP1 are key regulators of the unfolded protein response (UPR). XBP1 ablation causes profound hypolipidemia in mice, and triggers feedback activation of its upstream enzyme IRE1a, instigating regulated IRE1-dependent decay (RIDD), an mRNA degradation mechanism dependent on IRE1a's endoribonuclease activity. Comprehensive microarray analysis of XBP1 and/or IRE1a deficient liver identified genes involved in lipogenesis and lipoprotein metabolism as RIDD substrates, which might contribute to the suppression of plasma lipid levels by activated IRE1a.
2012-10-17 | GSE40515 | GEO
Project description:Background/Aims: Cholestatic liver diseases (CLD) are the leading indication for pediatric liver transplantation. Increased intrahepatic bile acid concentrations cause endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) is activated to maintain homeostasis. UPR dysregulation, including the inositol-requiring enzyme 1α/X-box protein 1 (IRE1α/XBP1) pathway, is associated with several adult liver diseases. We evaluated hepatic UPR expression in pediatric patients with end-stage CLD and hypothesize that an inability to appropriately activate the hepatic IRE1α/XBP1 pathway is associated with the pathogenesis of CLD. Methods: We evaluated 34 human liver explants. Cohorts included: pediatric CLD (Alagille, ALGS, and progressive familial intrahepatic cholestasis, PFIC), pediatric non-cholestatic liver disease controls (autoimmune hepatitis, AIH), adult CLD, and normal controls. We performed RNA-seq, quantitative PCR, and western blotting to measure expression differences of the hepatic UPR and other signaling pathways. Results: Metascape pathway analysis demonstrated that the KEGG ‘protein processing in ER’ pathway was downregulated in pediatric CLD compared to normal controls. Pediatric CLD had decreased hepatic IRE1α/XBP1 pathway gene expression and decreased protein expression of p-IRE1α compared to normal controls. These CLD changes were not disease-specific to ALGS or PFIC. IRE1α/XBP1 pathway gene expression was decreased in pediatric CLD compared to AIH disease controls. Conclusion: Pediatric CLD explants have decreased gene and protein expression of the protective IRE1α/XBP1 pathway and down-regulated KEGG protein processing in the ER pathways. IRE1α/XBP1 pathway expression differences occur when compared to both normal and non-cholestatic disease controls. Attenuated expression of the IRE1α/XBP1 pathway is associated with cholestatic diseases and could be targeted to treat pediatric CLD.
2022-06-23 | GSE206364 | GEO