title: Reciprocal regulation between proinflammatory cytokine-induced inducible NO synthase (iNOS) and connexin43 in bladder smooth muscle cells.
abstract: Gap junctions (GJs) play an important role in the control of bladder contractile response and in the regulation of various immune inflammatory processes. Here, we investigated the possible interaction between inflammation and GJs in bladder smooth muscle cells (BSMCs). Stimulation of BSMCs with IL1β and TNFα increased connexin43 (Cx43) expression and function, which was associated with increased phosphorylation of vasodilator-stimulated phosphoprotein. Inhibition of PKA with H89 or down-regulation of CREB with specific siRNAs largely abolished the Cx43-elevating effect. Further analysis revealed that IL1β/TNFα induced NFκB-dependent inducible NO synthase (iNOS) expression. Inhibition of iNOS with G-nitro-l-arginine methyl ester abrogated and an exogenous NO donor mimicked the effect of the cytokines on Cx43. Intraperitoneal injection of LPS into mice also induced bladder Cx43 expression, which was largely blocked by an iNOS inhibitor. Finally, the elevated Cx43 was found to negatively regulate iNOS expression. Dysfunction of GJs with various blockers or down-regulation of Cx43 with siRNA significantly potentiated the expression of iNOS. Fibroblasts from Cx43 knock-out (Cx43(-/-)) mice also displayed a significantly higher response to the cytokine-induced iNOS expression than cells from Cx43 wild-type (Cx43(+/+)) littermates. Collectively, our study revealed a previously unrecognized reciprocal regulation loop between cytokine-induced NO and GJs. Our findings may provide an important molecular mechanism for the symptoms of bladder infection. In addition, it may further our understanding of the roles of GJs in inflammatory diseases.
authors.affiliation: Department of Molecular Signaling, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan; Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan; Department of Oncology, China Medical University, Shenyang 110001, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Molecular Signaling, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan. Electronic address: yao@yamanashi.ac.jp.
authors.forename: Jian
authors.initials: J
authors.lastname: Yao
authors.affiliation: Department of Cardiology, First Affiliated Hospital, China Medical University, Shenyang 110001, China.
authors.forename: Liye
authors.initials: L
authors.lastname: Shi
authors.affiliation: Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Norifumi
authors.initials: N
authors.lastname: Sawada
authors.affiliation: Department of Molecular Signaling, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chi
authors.affiliation: Department of Molecular Signaling, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Qiaojing
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Department of Dermatology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsue
authors.affiliation: Department of Molecular Signaling, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kitamura
authors.affiliation: Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018031:Connexin 43 / Q000096:biosynthesis* / Q000235:genetics; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D003556:Cystitis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D053583:Interleukin-1beta / Q000378:metabolism* / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D001743:Urinary Bladder / Q000378:metabolism* / Q000473:pathology
chemical_list: D018031:Connexin 43; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat