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XBP1s Is an Anti-lipogenic Protein.

ABSTRACT: Endoplasmic reticulum (ER) stress has been shown to contribute to various metabolic diseases, including non-alcoholic fatty liver disease and type 2 diabetes. Reduction of ER stress by treatment with chemical chaperones or overexpression of ER chaperone proteins alleviates hepatic steatosis. Nonetheless, X-box binding protein 1s (XBP1s), a key transcription factor that reduces ER stress, has been proposed as a lipogenic transcription factor. In this report, we document that XBP1s leads to suppression of lipogenic gene expression and reduction of hepatic triglyceride and diacylglycerol content in livers of diet-induced obese and genetically obese and insulin-resistant ob/ob mice. Furthermore, we also show that PKC? activity, which correlates with fatty liver and which causes insulin resistance, was significantly reduced in diet-induced obese mice. Finally, we have shown that XBP1s reduces the hepatic fatty acid synthesis rate and enhances macrolipophagy, an initiating step in lipolysis. Our results reveal that XBP1s reduces hepatic lipogenic gene expression and improves hepatosteatosis in mouse models of obesity and insulin resistance, which leads us to conclude that XBP1s has anti-lipogenic properties in the liver.

SUBMITTER: Herrema H

PROVIDER: S-EPMC5016136 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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XBP1s Is an Anti-lipogenic Protein.

Herrema Hilde H Zhou Yingjiang Y Zhang Dongyan D Lee Justin J Salazar Hernandez Mario Andres MA Shulman Gerald I GI Ozcan Umut U

The Journal of biological chemistry 20160620 33

Endoplasmic reticulum (ER) stress has been shown to contribute to various metabolic diseases, including non-alcoholic fatty liver disease and type 2 diabetes. Reduction of ER stress by treatment with chemical chaperones or overexpression of ER chaperone proteins alleviates hepatic steatosis. Nonetheless, X-box binding protein 1s (XBP1s), a key transcription factor that reduces ER stress, has been proposed as a lipogenic transcription factor. In this report, we document that XBP1s leads to suppre ...[more]

PMID: 27325692

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Project description:Background: Resveratrol has been demonstrated to exert pleiotropic health beneficial effects. Among the various mechanisms of action antioxidant, anti-inflammatory, cardio- and cancer-protective outcomes have been reported. Particularly, an important function of this natural compound against atherosclerosis has been postulated and the action of resveratrol on lipids and lipoprotein levels seems to be of relevance in this pathology, but also for other metabolic diseases. Accordingly, taking into consideration the straight contact of resveratrol with the intestine, this study aimed to gain insights into the protective effects of trans-resveratrol on enterocyte physiology and metabolism in proinflammatory conditions. For this purpose, a DNA microarray analysis was conducted in Caco-2 cells where global gene expression profile at intestinal level was screened. Cells were pretreated with 50 Î¼Î? of trans-resveratrol and, subsequently, lipopolysaccharide (LPS) was added for 48 h. Results: The microarray analysis revealed 121 genes differentially expressed between resveratrol-treated and non-treated cells (B> 0). Four genes, inhibitor of DNA binding 1(ID1), histidine-rich glycoprotein (HRG), NADPH oxidase (NOX1) and sprouty homolog 1 (SPRY), were upregulated by LPS treatment, but significantly downregulated with trans-resveratrol pretreatment (padj< 0.05). Moreover, genes implicated in pathways related to lipid metabolism, such as synthesis of lipids (z-score= -1.195) and concentration of cholesterol (z-score= -0.109), were markedly downregulated by trans-resveratrol. Other genes implicated in lipid metabolism, but also in cell death and survival function, such as transcription factors KrÃ¼ppel-like factor 5 (KLF5) and amphiregulin (AREG), were also significantly inhibited by trans-resveratrol pretreatment. RT-qPCR-data confirmed the microarray results. Special mention deserves acyl-CoA synthetase long-chain family member 3 (ACSL3) and endothelial lipase (LIPG), which were downregulated by the stilbene and have been previously associated with fatty acid synthesis and obesity in other tissues. Conclusions: This study envisages that trans-resveratrol might exert important anti-lipogenic effect at intestinal level under proinflammatory conditions, which have not been previously described. The experiment was conducte in Caco-2 cells. There were three experimental groups (n=5), Caco-2 cells stimulated with lipopolysaccharides (LPS), Caco-2 cells stimulated with LPS and pre-treated with trans-resveratrol (LPS+RSV) and non-treated Caco-2 cells.

Project description:Background: Resveratrol has been demonstrated to exert pleiotropic health beneficial effects. Among the various mechanisms of action antioxidant, anti-inflammatory, cardio- and cancer-protective outcomes have been reported. Particularly, an important function of this natural compound against atherosclerosis has been postulated and the action of resveratrol on lipids and lipoprotein levels seems to be of relevance in this pathology, but also for other metabolic diseases. Accordingly, taking into consideration the straight contact of resveratrol with the intestine, this study aimed to gain insights into the protective effects of trans-resveratrol on enterocyte physiology and metabolism in proinflammatory conditions. For this purpose, a DNA microarray analysis was conducted in Caco-2 cells where global gene expression profile at intestinal level was screened. Cells were pretreated with 50 μΜ of trans-resveratrol and, subsequently, lipopolysaccharide (LPS) was added for 48 h. Results: The microarray analysis revealed 121 genes differentially expressed between resveratrol-treated and non-treated cells (B> 0). Four genes, inhibitor of DNA binding 1(ID1), histidine-rich glycoprotein (HRG), NADPH oxidase (NOX1) and sprouty homolog 1 (SPRY), were upregulated by LPS treatment, but significantly downregulated with trans-resveratrol pretreatment (padj< 0.05). Moreover, genes implicated in pathways related to lipid metabolism, such as synthesis of lipids (z-score= -1.195) and concentration of cholesterol (z-score= -0.109), were markedly downregulated by trans-resveratrol. Other genes implicated in lipid metabolism, but also in cell death and survival function, such as transcription factors Krüppel-like factor 5 (KLF5) and amphiregulin (AREG), were also significantly inhibited by trans-resveratrol pretreatment. RT-qPCR-data confirmed the microarray results. Special mention deserves acyl-CoA synthetase long-chain family member 3 (ACSL3) and endothelial lipase (LIPG), which were downregulated by the stilbene and have been previously associated with fatty acid synthesis and obesity in other tissues. Conclusions: This study envisages that trans-resveratrol might exert important anti-lipogenic effect at intestinal level under proinflammatory conditions, which have not been previously described.

Project description:IntroductionThe unfolded protein response (UPR) has emerged as an important signaling pathway mediating anti-viral defenses to Respiratory Syncytial Virus (RSV) infection. Earlier we found that RSV replication predominantly activates the evolutionarily conserved Inositol Requiring Enzyme 1α (IRE1α)-X-Box Binding Protein 1 spliced (XBP1s) arm of the Unfolded Protein Response (UPR) producing inflammation, metabolic adaptation and cellular plasticity, yet the mechanisms how the UPR potentiates inflammation are not well understood.MethodsTo understand this process better, we examined the genomic response integrating RNA-seq and Cleavage Under Targets and Release Using Nuclease (CUT&RUN) analyses. These data were integrated with an RNA-seq analysis conducted on RSV-infected small airway cells ± an IRE1α RNAse inhibitor.ResultsWe identified RSV induced expression changes in ~3.2K genes; of these, 279 required IRE1α and were enriched in IL-10/cytokine signaling pathways. From this data set, we identify those genes directly under XBP1s control by CUT&RUN. Although XBP1s binds to ~4.2 K high-confidence genomic binding sites, surprisingly only a small subset of IL10/cytokine signaling genes are directly bound. We further apply CUT&RUN to find that RSV infection enhances XBP1s loading on 786 genomic sites enriched in AP1/Fra-1, RELA and SP1 binding sites. These control a subset of cytokine regulatory factor genes including IFN response factor 1 (IRF1), CSF2, NFKB1A and DUSP10. Focusing on the downstream role of IRF1, selective knockdown (KD) and overexpression experiments demonstrate IRF1 induction controls type I and -III interferon (IFN) and IFN-stimulated gene (ISG) expression, demonstrating that ISG are indirectly regulated by XBP1 through IRF1 transactivation. Examining the mechanism of IRF1 activation, we observe that XBP1s directly binds a 5' enhancer sequence whose XBP1s loading is increased by RSV. The functional requirement for the enhancer is demonstrated by targeting a dCas9-KRAB silencer, reducing IRF1 activation. Chromatin immunoprecipitation shows that XBP1 is required, but not sufficient, for RSV-induced recruitment of activated phospho-Ser2 Pol II to the enhancer.DiscussionWe conclude that XBP1s is a direct activator of a core subset of IFN and cytokine regulatory genes in response to RSV. Of these IRF1 is upstream of the type III IFN and ISG response. We find that RSV modulates the XBP1s binding complex on the IRF1 5' enhancer whose activation is required for IRF1 expression. These findings provide novel insight into how the IRE1α-XBP1s pathway potentiates airway mucosal anti-viral responses.

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XBP1s Is an Anti-lipogenic Protein.

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XBP1s Is an Anti-lipogenic Protein.

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