The Experts below are selected from a list of 9249 Experts worldwide ranked by ideXlab platform
Lingfang Zeng - One of the best experts on this subject based on the ideXlab platform.
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The interaction between XBP1 and eNOS contributes to endothelial cell migration.
Experimental cell research, 2018Co-Authors: Junyao Yang, Lingfang Zeng, Martin Danniel, Xiaocong Wang, Wen Wang, Lisong ShenAbstract:The X-box binding protein 1 (XBP1) is a pivotal transcription factor in the endoplasmic reticulum stress response. Our previous studies have proven that XBP1 is involved in vascular endothelial growth factor (VEGF)-mediated endothelial cell (EC) proliferation and angiogenesis. In this study, we used EC monolayer wound healing, tube formation and transwell migration models to explore the role of XBP1splicing in EC migration. We found that scratching on EC monolayer triggered XBP1splicing, which was attenuated by the presence of SU5416and LY294002, suggesting that VEGF signalling pathways may be involved. Over-expression of the spliced XBP1 (XBP1s) via Ad-XBP1s gene transfer increased while knockdown of IRE1αor XBP1 by ShRNA lentivirus suppressed EC migration. Over-expression of XBP1s up-regulated the nitric oxide synthase 3 (NOS3)mRNA through the 3'UTR-mediated stabilisation and increased eNOS protein translation. Further experiments demonstrated that miR-24 participated in the XBP1s-induced eNOSup-regulation and EC migration. Further co-IP and immunofluorescence staining assays revealed that protein kinase B (Akt), eNOS andXBP1s form a complex, resulting in Akt and eNOS nucleus relocation. These results suggest that XBP1 splicing can regulate eNOS expression and cellular location, leading to EC migration and therefore contributing to wound healing and angiogenesis.
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unspliced XBP1 confers vsmc homeostasis and prevents aortic aneurysm formation via foxo4 interaction
Circulation Research, 2017Co-Authors: Guizhen Zhao, Zeyu Cai, Ze Gong, Rongbo Dai, Lingfang Zeng, Wei KongAbstract:Rationale: Although not fully understood, the phenotypic transition of vascular smooth muscle cells exhibits at the early onset of the pathology of aortic aneurysms. Exploring the key regulators that are responsible for maintaining the contractile phenotype of vascular smooth muscle cells (VSMCs) may confer vascular homeostasis and prevent aneurysmal disease. XBP1 (X-box binding protein 1), which exists in a transcriptionally inactive unspliced form (XBP1u) and a spliced active form (XBP1s), is a key component in response to endoplasmic reticular stress. Compared with XBP1s, little is known about the role of XBP1u in vascular homeostasis and disease. Objective: We aim to investigate the role of XBP1u in VSMC phenotypic switching and the pathogenesis of aortic aneurysms. Methods and Results: XBP1u, but not XBP1s, was markedly repressed in the aorta during the early onset of aortic aneurysm in both angiotensin II–infused apolipoprotein E knockout (ApoE −/− ) and CaPO 4 (calcium phosphate)-induced C57BL/6J murine models, in parallel with a decrease in smooth muscle cell contractile apparatus proteins. In vivo studies revealed that XBP1 deficiency in smooth muscle cells caused VSMC dedifferentiation, enhanced vascular inflammation and proteolytic activity, and significantly aggravated both thoracic and abdominal aortic aneurysms in mice. XBP1 deficiency, but not an inhibition of XBP1 splicing, induced VSMC switching from the contractile phenotype to a proinflammatory and proteolytic phenotype. Mechanically, in the cytoplasm, XBP1u directly associated with the N terminus of FoxO4 (Forkhead box protein O 4), a recognized repressor of VSMC differentiation via the interaction and inhibition of myocardin. Blocking the XBP1u–FoxO4 interaction facilitated nuclear translocation of FoxO4, repressed smooth muscle cell marker genes expression, promoted proinflammatory and proteolytic phenotypic transitioning in vitro, and stimulated aortic aneurysm formation in vivo. Conclusions: Our study revealed the pivotal role of the XBP1u–FoxO4–myocardin axis in maintaining the VSMC contractile phenotype and providing protection from aortic aneurysm formation.
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Abstract 654: XBP1 Splicing is Involved in Endothelial and Smooth Muscle Cells Interaction
Arteriosclerosis Thrombosis and Vascular Biology, 2015Co-Authors: Junyao Yang, Lingfang ZengAbstract:Background: The X-box binding protein 1 (XBP1) is a stress inducible transcription factors, essential for cell survival under stress conditions. Our previous studies have revealed that XBP1 participates in endothelial cell (EC) proliferation, autophagic response and survival and in smooth muscle cell (SMC) proliferation. Whether XBP1 is involved in EC/SMC interaction remains unclear. Methods and Results: In this study, we first performed hindlimb ischemia model in XBP1loxP/loxP and SM22-Cre+/XBP1loxP/loxP mice. The XBP1 deficiency in SMCs significantly attenuated the recovery of foot blood perfusion in ischemic mice. Immunofluorescence staining revealed that ECs lost contact to each other in XBP1 deficient mice, suggesting that XBP1 in SMCs may contribute to EC/SMC interaction. The conditioned medium from Ad-XBP1s-infected SMCs increased EC migration and proliferation. The conditioned medium from Ad-XBP1s-infected ECs also increased SMC migration but suppressed SMC proliferation. The migration effect coul...
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Gang Wang, Lingfang ZengAbstract:It is well known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box-binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a VEGF receptor and PI3K/Akt-dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Overexpression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization, and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation, and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3, and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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YIA1 Interaction between HDAC3 and XBP1 is critical in maintainence of endothelial integrity
Heart, 2010Co-Authors: D Martin, Anna Zampetaki, Lingfang ZengAbstract:Histone deacetylases (HDACs) play a crucial role in transcriptional regulation through modulation of chromatin structure. The class I HDAC, HDAC3, is involved in maintaining endothelial cell integrity.1 Sustained activation of the x-box binding protein 1 (XBP1), an endoplasmic reticulum stress response transcription factor, results in the development of atherosclerosis in apoE−/− mice.2 HDAC3 and XBP1 are similarly expressed in the bifurcation regions of the aorta. In this study, we investigated whether cross-talk existed between HDAC3 and XBP1, and its role in the maintenance of endothelial cell integrity. Our study demonstrated that disturbed flow upregulated HDAC3 and unspliced XBP1 (XBP1u) protein production through the KDR/PI3K/Akt pathway. Knockdown of XBP1 by shRNA lentiviral transfection ablated disturbed flow-induced HDAC3 upregulation. Similarly to HDAC3, overexpression of XBP1u by adenoviral gene transfer increased Akt phosphorylation at Serine473 and haem oxygenase 1 gene transcription, which showed a protective role in hydrogen peroxide-induced apoptosis of endothelial cells. Co-immunoprecipitation assays demonstrated that HDAC3 physically associates with XBP1u and this could be enhanced by disturbed flow and VEGF treatment. The use of truncated HDAC3 constructs demonstrated that XBP1 binds to the central section of HDAC3. Further experiments indicated that overexpression of XBP1u increased the binding of HDAC3 to IRE1α, Akt and PI3K, especially after VEGF treatment. In contrast, sustained activation of spliced XBP1 decreased HDAC3 protein production through transcriptional suppression, leading to endothelial apoptosis. These results suggest that XBP1u protects endothelial cells from oxidative stress by interacting with HDAC3. Targeting this interaction may provide novel therapeutic strategies for vascular disease via maintaining endothelial integrity.
Anna Zampetaki - One of the best experts on this subject based on the ideXlab platform.
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Yanhua Hu, Hui Yu, Gang Wang, Qingbo XuAbstract:Abstract It is well-known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a vascular endothelial growth factor receptor (VEGFR) and PI3K/Akt dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Over-expression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 Protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3 and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Gang Wang, Lingfang ZengAbstract:It is well known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box-binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a VEGF receptor and PI3K/Akt-dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Overexpression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization, and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation, and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3, and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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XBP1 mrna splicing triggers an autophagic response in endothelial cells through beclin 1 transcriptional activation
Journal of Biological Chemistry, 2013Co-Authors: Andriana Margariti, Anna Zampetaki, Daniel Martin, Saydul Alam, Qingzhong Xiao, Ting Chen, Gema Vizcaybarrena, Eirini Karamariti, Zhongyi Zhang, Wen WangAbstract:Sustained activation of X-box-binding protein 1 (XBP1) results in endothelial cell (EC) apoptosis and atherosclerosis development. The present study provides evidence that XBP1 mRNA splicing triggered an autophagic response in ECs by inducing autophagic vesicle formation and markers of autophagy BECLIN-1 and microtubule-associated protein 1 light chain 3β (LC3-βII). Endostatin activated autophagic gene expression through XBP1 mRNA splicing in an inositol-requiring enzyme 1α (IRE1α)-dependent manner. Knockdown of XBP1 or IRE1α by shRNA in ECs ablated endostatin-induced autophagosome formation. Importantly, data from arterial vessels from XBP1 EC conditional knock-out (XBP1eko) mice demonstrated that XBP1 deficiency in ECs reduced the basal level of LC3β expression and ablated response to endostatin. Chromatin immunoprecipitation assays further revealed that the spliced XBP1 isoform bound directly to the BECLIN-1 promoter at the region from nt −537 to −755. BECLIN-1 deficiency in ECs abolished the XBP1-induced autophagy response, whereas spliced XBP1 did not induce transcriptional activation of a truncated BECLIN-1 promoter. These results suggest that XBP1 mRNA splicing triggers an autophagic signal pathway through transcriptional regulation of BECLIN-1. Background: Apoptosis and autophagy are two closely related systems that induce cell death. Results: X-box-binding protein 1 (XBP1) mRNA splicing regulates BECLIN-1 transcriptional activation, a fundamental player in the initiation of autophagy. Conclusion: XBP1 splicing induces an autophagic response in endothelial cells. Significance: XBP1 could be used as an important pharmacological target that can regulate the autophagic machinery and endothelial cell death.
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YIA1 Interaction between HDAC3 and XBP1 is critical in maintainence of endothelial integrity
Heart, 2010Co-Authors: D Martin, Anna Zampetaki, Lingfang ZengAbstract:Histone deacetylases (HDACs) play a crucial role in transcriptional regulation through modulation of chromatin structure. The class I HDAC, HDAC3, is involved in maintaining endothelial cell integrity.1 Sustained activation of the x-box binding protein 1 (XBP1), an endoplasmic reticulum stress response transcription factor, results in the development of atherosclerosis in apoE−/− mice.2 HDAC3 and XBP1 are similarly expressed in the bifurcation regions of the aorta. In this study, we investigated whether cross-talk existed between HDAC3 and XBP1, and its role in the maintenance of endothelial cell integrity. Our study demonstrated that disturbed flow upregulated HDAC3 and unspliced XBP1 (XBP1u) protein production through the KDR/PI3K/Akt pathway. Knockdown of XBP1 by shRNA lentiviral transfection ablated disturbed flow-induced HDAC3 upregulation. Similarly to HDAC3, overexpression of XBP1u by adenoviral gene transfer increased Akt phosphorylation at Serine473 and haem oxygenase 1 gene transcription, which showed a protective role in hydrogen peroxide-induced apoptosis of endothelial cells. Co-immunoprecipitation assays demonstrated that HDAC3 physically associates with XBP1u and this could be enhanced by disturbed flow and VEGF treatment. The use of truncated HDAC3 constructs demonstrated that XBP1 binds to the central section of HDAC3. Further experiments indicated that overexpression of XBP1u increased the binding of HDAC3 to IRE1α, Akt and PI3K, especially after VEGF treatment. In contrast, sustained activation of spliced XBP1 decreased HDAC3 protein production through transcriptional suppression, leading to endothelial apoptosis. These results suggest that XBP1u protects endothelial cells from oxidative stress by interacting with HDAC3. Targeting this interaction may provide novel therapeutic strategies for vascular disease via maintaining endothelial integrity.
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sustained activation of XBP1 splicing leads to endothelial apoptosis and atherosclerosis development in response to disturbed flow
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Lingfang Zeng, Anna Zampetaki, Andriana Margariti, Daniel Martin, Wen Wang, Anna Elena Pepe, Saydul Alam, Qingzhong Xiao, Zhenggen Jin, Gillian W CockerillAbstract:X-box binding protein 1 (XBP1) is a key signal transducer in endoplasmic reticulum stress response, and its potential role in the atherosclerosis development is unknown. This study aims to explore the impact of XBP1 on maintaining endothelial integrity related to atherosclerosis and to delineate the underlying mechanism. We found that XBP1 was highly expressed at branch points and areas of atherosclerotic lesions in the arteries of ApoE−/− mice, which was related to the severity of lesion development. In vitro study using human umbilical vein endothelial cells (HUVECs) indicated that disturbed flow increased the activation of XBP1 expression and splicing. Overexpression of spliced XBP1 induced apoptosis of HUVECs and endothelial loss from blood vessels during ex vivo cultures because of caspase activation and down-regulation of VE-cadherin resulting from transcriptional suppression and matrix metalloproteinase-mediated degradation. Reconstitution of VE-cadherin by Ad-VEcad significantly increased Ad-XBP1s-infected HUVEC survival. Importantly, Ad-XBP1s gene transfer to the vessel wall of ApoE−/− mice resulted in development of atherosclerotic lesions after aorta isografting. These results indicate that XBP1 plays an important role in maintaining endothelial integrity and atherosclerosis development, which provides a potential therapeutic target to intervene in atherosclerosis.
Daniel Martin - One of the best experts on this subject based on the ideXlab platform.
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Yanhua Hu, Hui Yu, Gang Wang, Qingbo XuAbstract:Abstract It is well-known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a vascular endothelial growth factor receptor (VEGFR) and PI3K/Akt dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Over-expression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 Protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3 and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Gang Wang, Lingfang ZengAbstract:It is well known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box-binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a VEGF receptor and PI3K/Akt-dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Overexpression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization, and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation, and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3, and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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XBP1 mrna splicing triggers an autophagic response in endothelial cells through beclin 1 transcriptional activation
Journal of Biological Chemistry, 2013Co-Authors: Andriana Margariti, Anna Zampetaki, Daniel Martin, Saydul Alam, Qingzhong Xiao, Ting Chen, Gema Vizcaybarrena, Eirini Karamariti, Zhongyi Zhang, Wen WangAbstract:Sustained activation of X-box-binding protein 1 (XBP1) results in endothelial cell (EC) apoptosis and atherosclerosis development. The present study provides evidence that XBP1 mRNA splicing triggered an autophagic response in ECs by inducing autophagic vesicle formation and markers of autophagy BECLIN-1 and microtubule-associated protein 1 light chain 3β (LC3-βII). Endostatin activated autophagic gene expression through XBP1 mRNA splicing in an inositol-requiring enzyme 1α (IRE1α)-dependent manner. Knockdown of XBP1 or IRE1α by shRNA in ECs ablated endostatin-induced autophagosome formation. Importantly, data from arterial vessels from XBP1 EC conditional knock-out (XBP1eko) mice demonstrated that XBP1 deficiency in ECs reduced the basal level of LC3β expression and ablated response to endostatin. Chromatin immunoprecipitation assays further revealed that the spliced XBP1 isoform bound directly to the BECLIN-1 promoter at the region from nt −537 to −755. BECLIN-1 deficiency in ECs abolished the XBP1-induced autophagy response, whereas spliced XBP1 did not induce transcriptional activation of a truncated BECLIN-1 promoter. These results suggest that XBP1 mRNA splicing triggers an autophagic signal pathway through transcriptional regulation of BECLIN-1. Background: Apoptosis and autophagy are two closely related systems that induce cell death. Results: X-box-binding protein 1 (XBP1) mRNA splicing regulates BECLIN-1 transcriptional activation, a fundamental player in the initiation of autophagy. Conclusion: XBP1 splicing induces an autophagic response in endothelial cells. Significance: XBP1 could be used as an important pharmacological target that can regulate the autophagic machinery and endothelial cell death.
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sustained activation of XBP1 splicing leads to endothelial apoptosis and atherosclerosis development in response to disturbed flow
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Lingfang Zeng, Anna Zampetaki, Andriana Margariti, Daniel Martin, Wen Wang, Anna Elena Pepe, Saydul Alam, Qingzhong Xiao, Zhenggen Jin, Gillian W CockerillAbstract:X-box binding protein 1 (XBP1) is a key signal transducer in endoplasmic reticulum stress response, and its potential role in the atherosclerosis development is unknown. This study aims to explore the impact of XBP1 on maintaining endothelial integrity related to atherosclerosis and to delineate the underlying mechanism. We found that XBP1 was highly expressed at branch points and areas of atherosclerotic lesions in the arteries of ApoE−/− mice, which was related to the severity of lesion development. In vitro study using human umbilical vein endothelial cells (HUVECs) indicated that disturbed flow increased the activation of XBP1 expression and splicing. Overexpression of spliced XBP1 induced apoptosis of HUVECs and endothelial loss from blood vessels during ex vivo cultures because of caspase activation and down-regulation of VE-cadherin resulting from transcriptional suppression and matrix metalloproteinase-mediated degradation. Reconstitution of VE-cadherin by Ad-VEcad significantly increased Ad-XBP1s-infected HUVEC survival. Importantly, Ad-XBP1s gene transfer to the vessel wall of ApoE−/− mice resulted in development of atherosclerotic lesions after aorta isografting. These results indicate that XBP1 plays an important role in maintaining endothelial integrity and atherosclerosis development, which provides a potential therapeutic target to intervene in atherosclerosis.
Annhwee Lee - One of the best experts on this subject based on the ideXlab platform.
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A negative feedback loop between XBP1 and Fbw7 regulates cancer development
Oncogenesis, 2019Co-Authors: Unbin Chae, Annhwee Lee, Bokyung Kim, Dong-seok Lee, Heejin Lee, Haiyoung Jung, Byeong Mo Kim, Sang-hyun MinAbstract:In cancer, activation of X-box binding protein (XBP1) has a critical role in tumorigenesis and cancer progression. Transcriptional regulatory mechanism of XBP1 in cancer development has been well known, however, regulation of ubiquitination and degradation of XBP1 has not been elucidated yet. Here we show that Fbw7, a substrate recognition component of the SKP1-Cullin-F-box-type E3 ligase, interacts with XBP1 in a phosphorylation-dependent manner, and facilitates XBP1 ubiquitination and protein degradation. Moreover, Fbw7 inhibits oncogenic pathways including NF-κB, AP1, and Myc induced by XBP1. Interestingly, XBP1 negatively regulates transcription of Fbw7 via a feedback mechanism through NF-κB/E2F-1 axis signaling pathway, suggesting that overexpression of XBP1s may contribute to low level of Fbw7 expression in human cancers. Therefore, a negative feedback loop between Fbw7 and XBP1 contributes to the regulation of tumor development and can be an attractive target for novel therapy in cancers.
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Spliced XBP1 Rescues Renal Interstitial Inflammation Due to Loss of Sec63 in Collecting Ducts.
Journal of the American Society of Nephrology : JASN, 2019Co-Authors: Yasunobu Ishikawa, Annhwee Lee, Sorin V. Fedeles, Arnaud Marlier, Chao Zhang, Anna Rachel Gallagher, Stefan SomloAbstract:Background SEC63 encodes a resident protein in the endoplasmic reticulum membrane that, when mutated, causes human autosomal dominant polycystic liver disease. Selective inactivation of Sec63 in all distal nephron segments in embryonic mouse kidney results in polycystin-1–mediated polycystic kidney disease (PKD). It also activates the Ire1 α -XBP1 branch of the unfolded protein response, producing XBP1s, the active transcription factor promoting expression of specific genes to alleviate endoplasmic reticulum stress. Simultaneous inactivation of XBP1 and Sec63 worsens PKD in this model. Methods We explored the renal effects of postnatal inactivation of Sec63 alone or with concomitant inactivation of XBP1 or Ire1α , specifically in the collecting ducts of neonatal mice. Results The later onset of inactivation of Sec63 restricted to the collecting duct does not result in overt activation of the Ire1 α -XBP1 pathway or cause polycystin-1–dependent PKD. Inactivating Sec63 along with either XBP1 or Ire1α in this model causes interstitial inflammation and associated fibrosis with decline in kidney function over several months. Re-expression of XBP1s in vivo completely rescues the chronic kidney injury observed after inactivation of Sec63 with either XBP1 or Ire1α . Conclusions In the absence of Sec63 , basal levels of XBP1s activity in collecting ducts is both necessary and sufficient to maintain proteostasis (protein homeostasis) and protect against inflammation, myofibroblast activation, and kidney functional decline. The Sec63-XBP1 double knockout mouse offers a novel genetic model of chronic tubulointerstitial kidney injury, using collecting duct proteostasis defects as a platform for discovery of signals that may underlie CKD of disparate etiologies.
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Critical role of XBP1 in cancer signalling is regulated by PIN1
The Biochemical journal, 2016Co-Authors: Unbin Chae, Annhwee Lee, Sun-ji Park, Bokyung Kim, Shou Wei, Ju-sik Min, Jun-hyeog Lee, Hoon Park, Dong-seok LeeAbstract:XBP1 (X-box-binding protein 1) is activated in cancer and has a pivotal role in tumorigenesis and progression of human cancer. In particular, the XBP1 transcriptional regulatory network is well known to drive cancer development, but little is known about whether the stability of XBP1 is regulated and, if so, what controls the stability of XBP1. In the present study we show that PIN1 prolyl isomerase interacts with the active form of XBP1 (XBP1s) in a phosphorylation-dependent manner and promotes XBP1s-induced cell proliferation and transformation through the regulation of XBP1 stability. By contrast, depletion of Pin1 in cancer cells reduced XBP1s expression, which subsequently inhibits cell proliferation and transformation. Interestingly, XBP1s activates multiple oncogenic pathways including NF-κB (nuclear factor κB), AP1 (activator protein 1) and Myc, and down-regulates PIN1 transcription via a negative-feedback mechanism through p53 induction. Ultimately, reciprocal regulation of Pin1 and XBP1s is associated with the activation of oncogenic pathways, and the relationship of PIN1 and XBP1 may be an attractive target for novel therapy in cancers.
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Sec63 and XBP1 regulate IRE1α activity and polycystic disease severity
The Journal of clinical investigation, 2015Co-Authors: Sorin V. Fedeles, Anna Rachel Gallagher, Stefan Somlo, Amol Shrikhande, Seunghun Lee, Christina E. Barkauskas, Annhwee LeeAbstract:The HSP40 cochaperone SEC63 is associated with the SEC61 translocon complex in the ER. Mutations in the gene encoding SEC63 cause polycystic liver disease in humans; however, it is not clear how altered SEC63 influences disease manifestations. In mice, loss of SEC63 induces cyst formation both in liver and kidney as the result of reduced polycystin-1 (PC1). Here we report that inactivation of SEC63 induces an unfolded protein response (UPR) pathway that is protective against cyst formation. Specifically, using murine genetic models, we determined that SEC63 deficiency selectively activates the IRE1α-XBP1 branch of UPR and that SEC63 exists in a complex with PC1. Concomitant inactivation of both SEC63 and XBP1 exacerbated the polycystic kidney phenotype in mice by markedly suppressing cleavage at the G protein–coupled receptor proteolysis site (GPS) in PC1. Enforced expression of spliced XBP1 (XBP1s) enhanced GPS cleavage of PC1 in SEC63-deficient cells, and XBP1 overexpression in vivo ameliorated cystic disease in a murine model with reduced PC1 function that is unrelated to SEC63 inactivation. Collectively, the findings show that SEC63 function regulates IRE1α/XBP1 activation, SEC63 and XBP1 are required for GPS cleavage and maturation of PC1, and activation of XBP1 can protect against polycystic disease in the setting of impaired biogenesis of PC1.
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dissociation of inositol requiring enzyme ire1α mediated c jun n terminal kinase activation from hepatic insulin resistance in conditional x box binding protein 1 XBP1 knock out mice
Journal of Biological Chemistry, 2012Co-Authors: Michael J Jurczak, Annhwee Lee, Laurie H Glimcher, Francois R Jornayvaz, Huiyoung Lee, Andreas L Birkenfeld, Blas A Guigni, Mario Kahn, Varman T Samuel, Gerald I ShulmanAbstract:Hepatic insulin resistance has been attributed to both increased endoplasmic reticulum (ER) stress and accumulation of intracellular lipids, specifically diacylglycerol (DAG). The ER stress response protein, X-box-binding protein-1 (XBP1), was recently shown to regulate hepatic lipogenesis, suggesting that hepatic insulin resistance in models of ER stress may result from defective lipid storage, as opposed to ER-specific stress signals. Studies were designed to dissociate liver lipid accumulation and activation of ER stress signaling pathways, which would allow us to delineate the individual contributions of ER stress and hepatic lipid content to the pathogenesis of hepatic insulin resistance. Conditional XBP1 knock-out (XBP1Δ) and control mice were fed fructose chow for 1 week. Determinants of whole-body energy balance, weight, and composition were determined. Hepatic lipids including triglyceride, DAGs, and ceramide were measured, alongside markers of ER stress. Whole-body and tissue-specific insulin sensitivity were determined by hyperinsulinemic-euglycemic clamp studies. Hepatic ER stress signaling was increased in fructose chow-fed XBP1Δ mice as reflected by increased phosphorylated eIF2α, HSPA5 mRNA, and a 2-fold increase in hepatic JNK activity. Despite JNK activation, XBP1Δ displayed increased hepatic insulin sensitivity during hyperinsulinemic-euglycemic clamp studies, which was associated with increased insulin-stimulated IRS2 tyrosine phosphorylation, reduced hepatic DAG content, and reduced PKCϵ activity. These studies demonstrate that ER stress and IRE1α-mediated JNK activation can be disassociated from hepatic insulin resistance and support the hypothesis that hepatic insulin resistance in models of ER stress may be secondary to ER stress modulation of hepatic lipogenesis.
Andriana Margariti - One of the best experts on this subject based on the ideXlab platform.
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Yanhua Hu, Hui Yu, Gang Wang, Qingbo XuAbstract:Abstract It is well-known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a vascular endothelial growth factor receptor (VEGFR) and PI3K/Akt dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Over-expression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 Protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3 and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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unspliced x box binding protein 1 XBP1 protects endothelial cells from oxidative stress through interaction with histone deacetylase 3
Journal of Biological Chemistry, 2014Co-Authors: Daniel Martin, Anna Zampetaki, Junyao Yang, Zhixin Jiang, Andriana Margariti, Gang Wang, Lingfang ZengAbstract:It is well known that atherosclerosis occurs geographically at branch points where disturbed flow predisposes to the development of plaque via triggering of oxidative stress and inflammatory reactions. In this study, we found that disturbed flow activated anti-oxidative reactions via up-regulating heme oxygenase 1 (HO-1) in an X-box-binding protein 1 (XBP1) and histone deacetylase 3 (HDAC3)-dependent manner. Disturbed flow concomitantly up-regulated the unspliced XBP1 (XBP1u) and HDAC3 in a VEGF receptor and PI3K/Akt-dependent manner. The presence of XBP1 was essential for the up-regulation of HDAC3 protein. Overexpression of XBP1u and/or HDAC3 activated Akt1 phosphorylation, Nrf2 protein stabilization and nuclear translocation, and HO-1 expression. Knockdown of XBP1u decreased the basal level and disturbed flow-induced Akt1 phosphorylation, Nrf2 stabilization, and HO-1 expression. Knockdown of HDAC3 ablated XBP1u-mediated effects. The mammalian target of rapamycin complex 2 (mTORC2) inhibitor, AZD2014, ablated XBP1u or HDAC3 or disturbed flow-mediated Akt1 phosphorylation, Nrf2 nuclear translocation, and HO-1 expression. Neither actinomycin D nor cycloheximide affected disturbed flow-induced up-regulation of Nrf2 protein. Knockdown of Nrf2 abolished XBP1u or HDAC3 or disturbed flow-induced HO-1 up-regulation. Co-immunoprecipitation assays demonstrated that XBP1u physically bound to HDAC3 and Akt1. The region of amino acids 201 to 323 of the HDAC3 protein was responsible for the binding to XBP1u. Double immunofluorescence staining revealed that the interactions between Akt1 and mTORC2, Akt1 and HDAC3, Akt1 and XBP1u, HDAC3, and XBP1u occurred in the cytosol. Thus, we demonstrate that XBP1u and HDAC3 exert a protective effect on disturbed flow-induced oxidative stress via up-regulation of mTORC2-dependent Akt1 phosphorylation and Nrf2-mediated HO-1 expression.
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XBP1 mrna splicing triggers an autophagic response in endothelial cells through beclin 1 transcriptional activation
Journal of Biological Chemistry, 2013Co-Authors: Andriana Margariti, Anna Zampetaki, Daniel Martin, Saydul Alam, Qingzhong Xiao, Ting Chen, Gema Vizcaybarrena, Eirini Karamariti, Zhongyi Zhang, Wen WangAbstract:Sustained activation of X-box-binding protein 1 (XBP1) results in endothelial cell (EC) apoptosis and atherosclerosis development. The present study provides evidence that XBP1 mRNA splicing triggered an autophagic response in ECs by inducing autophagic vesicle formation and markers of autophagy BECLIN-1 and microtubule-associated protein 1 light chain 3β (LC3-βII). Endostatin activated autophagic gene expression through XBP1 mRNA splicing in an inositol-requiring enzyme 1α (IRE1α)-dependent manner. Knockdown of XBP1 or IRE1α by shRNA in ECs ablated endostatin-induced autophagosome formation. Importantly, data from arterial vessels from XBP1 EC conditional knock-out (XBP1eko) mice demonstrated that XBP1 deficiency in ECs reduced the basal level of LC3β expression and ablated response to endostatin. Chromatin immunoprecipitation assays further revealed that the spliced XBP1 isoform bound directly to the BECLIN-1 promoter at the region from nt −537 to −755. BECLIN-1 deficiency in ECs abolished the XBP1-induced autophagy response, whereas spliced XBP1 did not induce transcriptional activation of a truncated BECLIN-1 promoter. These results suggest that XBP1 mRNA splicing triggers an autophagic signal pathway through transcriptional regulation of BECLIN-1. Background: Apoptosis and autophagy are two closely related systems that induce cell death. Results: X-box-binding protein 1 (XBP1) mRNA splicing regulates BECLIN-1 transcriptional activation, a fundamental player in the initiation of autophagy. Conclusion: XBP1 splicing induces an autophagic response in endothelial cells. Significance: XBP1 could be used as an important pharmacological target that can regulate the autophagic machinery and endothelial cell death.
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sustained activation of XBP1 splicing leads to endothelial apoptosis and atherosclerosis development in response to disturbed flow
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Lingfang Zeng, Anna Zampetaki, Andriana Margariti, Daniel Martin, Wen Wang, Anna Elena Pepe, Saydul Alam, Qingzhong Xiao, Zhenggen Jin, Gillian W CockerillAbstract:X-box binding protein 1 (XBP1) is a key signal transducer in endoplasmic reticulum stress response, and its potential role in the atherosclerosis development is unknown. This study aims to explore the impact of XBP1 on maintaining endothelial integrity related to atherosclerosis and to delineate the underlying mechanism. We found that XBP1 was highly expressed at branch points and areas of atherosclerotic lesions in the arteries of ApoE−/− mice, which was related to the severity of lesion development. In vitro study using human umbilical vein endothelial cells (HUVECs) indicated that disturbed flow increased the activation of XBP1 expression and splicing. Overexpression of spliced XBP1 induced apoptosis of HUVECs and endothelial loss from blood vessels during ex vivo cultures because of caspase activation and down-regulation of VE-cadherin resulting from transcriptional suppression and matrix metalloproteinase-mediated degradation. Reconstitution of VE-cadherin by Ad-VEcad significantly increased Ad-XBP1s-infected HUVEC survival. Importantly, Ad-XBP1s gene transfer to the vessel wall of ApoE−/− mice resulted in development of atherosclerotic lesions after aorta isografting. These results indicate that XBP1 plays an important role in maintaining endothelial integrity and atherosclerosis development, which provides a potential therapeutic target to intervene in atherosclerosis.
