title: Regulation of STIM1, store-operated Ca2+ influx, and nitric oxide generation by retinoic acid in rat mesangial cells.
abstract: It has been shown that store-operated Ca(2+) influx (SOC) plays critical roles in the activation of endothelial nitric oxide (NO) synthase (eNOS) and generation of NO in endothelial cells. Recent studies indicate stromal interaction molecule 1 (STIM1) is the molecule responsible for SOC activation following Ca(2+) depletion in the ER. Retinoic acids (RA) have beneficial effects in the treatment of renal diseases. The mechanism of the RA action is still largely unknown. In the current study, we used primary cultured rat mesangial cells to examine the effect of RA on SOC and STIM1. In these cells, BK caused concentration-dependent [Ca(2+)](i) mobilization. Treatment of the cells with RA, while it had no effect on the initial peak, reduced the plateau phase of BK-mediated [Ca(2+)](i) response, indicating the inhibition of SOC by RA. The level of STIM1 protein but not mRNA in RA-treated cells was significantly reduced. RA treatment did not affect TGF-beta-mediated gradual Ca(2+) influx which occurred by superoxide anion-mediated mechanism, indicating RA treatment specifically inhibited SOC in mesangial cells. RT-PCR and Western blot analysis demonstrated that eNOS was expressed in rat mesangial cells grown in media containing 11 and 30 but not 5.5 mM glucose. Downregulation of STIM1 protein and BK-induced SOC by RA treatment or STIM1 dsRNA were associated with abolished NO production. The 26S proteasome inhibitor lactacystin blocked the RA-mediated downregulation of BK-induced SOC, suggesting that ubiquitin-proteasome pathway may be involved in RA-mediated STIM1 protein downregulation in rat mesangial cells. Our data suggest that glucose-induced eNOS expression and NO production in mesangial cells may contribute to hyperfiltration in diabetes and RA may exert beneficial effects by downregulation of STIM1 and SOC in mesangial cells.
authors.affiliation: Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, Audie L. Murphy Division, University of Texas Health Science Center San Antonio, San Antonio, Texas, USA.
authors.forename: Wanke
authors.initials: W
authors.lastname: Zhang
authors.forename: Hua
authors.initials: H
authors.lastname: Meng
authors.forename: Zhen-Hua
authors.initials: ZH
authors.lastname: Li
authors.forename: Zhenju
authors.initials: Z
authors.lastname: Shu
authors.forename: Xiuye
authors.initials: X
authors.lastname: Ma
authors.forename: Bin-Xian
authors.initials: BX
authors.lastname: Zhang
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D050527:Mesangial Cells / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D061988:Proteasome Inhibitors; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071737:Stromal Interaction Molecule 1; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D015853:Cysteine Proteinase Inhibitors; D008562:Membrane Glycoproteins; D061988:Proteasome Inhibitors; D034741:RNA, Small Interfering; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D016212:Transforming Growth Factor beta; C067713:lactacystin; D009569:Nitric Oxide; D014212:Tretinoin; D052250:Nitric Oxide Synthase Type III; D005947:Glucose; D001920:Bradykinin; D002118:Calcium; D000111:Acetylcysteine