title: Critical role of X-box binding protein 1 in NADPH oxidase 4-triggered cardiac hypertrophy is mediated by receptor interacting protein kinase 1.
abstract: NADPH oxidase 4 (NOX4) and the NOX4-related redox signaling are implicated in cardiac hypertrophy. NOX4 is interrelated with endoplasmic reticulum stress (ERS). Spliced X-box binding protein 1 (Xbp1s) is a key mediator of ERS while its role in cardiac hypertrophy is still poorly understood. Recently, receptor interacting protein kinase 1(RIPK1) has been increasingly reported to be associated with ERS. Therefore, we aimed to test the hypothesis that Xbp1s mediates NOX4-triggered cardiac hypertrophy via RIPK1 signaling. In the heart tissue of transverse aortic constriction (TAC) rats and in primary cultured neonatal cardiomyocytes(NCMs) treated with angiotensinII(AngII) or isoproterenol (ISO), NOX4 expression and reactive oxygen species (ROS) generation, and expression of Xbp1s as well as RIPK1-related phosphorylation of P65 subunit of NF-κB were elevated. Gene silencing of NOX4 by specific small interfering RNA (siRNA) significantly blocked the upregulation of NOX4, generation of ROS, splicing of Xbp1 and activation of the RIPK1-related NF-κB signaling, meanwhile attenuated cardiomyocyte hypertrophy. In addition, ROS scavenger (N-acetyl-L-cysteine, NAC) and NOX4 inhibitor GKT137831 reduced ROS generation and alleviated activation of Xbp1 and RIPK1-related NF-κB signaling. Furthermore, splicing of Xbp1 was responsible for the increase in RIPK1 expression in AngII or ISO-treated NCMs. Upregulated RIPK1 in turn activates NF-κB signaling in a kinase activity-independent manner. These findings suggest that Xbp1s plays an important role in NOX4-triggered cardiomyocyte hypertrophy via activating its downstream effector RIPK1, which may prove significant for the development of future therapeutic strategies.
authors.affiliation: a Department of Cardiology , West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: b Laboratory of Cardiovascular Diseases , Regenerative Medicine Research Center, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Mingyue
authors.initials: M
authors.lastname: Zhao
authors.affiliation: b Laboratory of Cardiovascular Diseases , Regenerative Medicine Research Center, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Junli
authors.initials: J
authors.lastname: Li
authors.affiliation: c Laboratory of Molecular Diagnosis of Cancer , State Key Laboratory of Biotherapy, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: a Department of Cardiology , West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Qinxue
authors.initials: Q
authors.lastname: Bao
authors.affiliation: b Laboratory of Cardiovascular Diseases , Regenerative Medicine Research Center, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Siyuan
authors.initials: S
authors.lastname: Wu
authors.affiliation: d Department of Pathology , West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Xueqin
authors.initials: X
authors.lastname: Deng
authors.affiliation: b Laboratory of Cardiovascular Diseases , Regenerative Medicine Research Center, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Xiaoju
authors.initials: X
authors.lastname: Tang
authors.affiliation: b Laboratory of Cardiovascular Diseases , Regenerative Medicine Research Center, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Wenchao
authors.initials: W
authors.lastname: Wu
authors.affiliation: a Department of Cardiology , West China Hospital, Sichuan University , Chengdu , P.R. China.|b Laboratory of Cardiovascular Diseases , Regenerative Medicine Research Center, West China Hospital, Sichuan University , Chengdu , P.R. China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000378:metabolism*; D020868:Gene Silencing; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D015398:Signal Transduction; D015854:Up-Regulation; D000071717:X-Box Binding Protein 1 / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D034741:RNA, Small Interfering; D000071717:X-Box Binding Protein 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498911:Nox4 protein, rat; D017346:Protein Serine-Threonine Kinases; C586536:RIPK1 protein, rat; D053422:Receptor-Interacting Protein Serine-Threonine Kinases
keywords: NADPH oxidase 4; X-box binding protein 1; cardiac hypertrophy; endoplasmic reticulum stress; receptor interacting protein kinase 1