title: Na+/Ca2+ exchanger activity modulates connective tissue growth factor mRNA expression in transforming growth factor beta1- and Des-Arg10-kallidin-stimulated myofibroblasts.
abstract: Transforming growth factor (TGF)-beta and des-Arg(10)-kallidin stimulate the expression of connective tissue growth factor (CTGF), a matrix signaling molecule that is frequently overexpressed in fibrotic disorders. Because the early signal transduction events regulating CTGF expression are unclear, we investigated the role of Ca(2+) homeostasis in CTGF mRNA expression in TGF-beta1- and des-Arg(10)-kallidin-stimulated human lung myofibroblasts. Activation of the kinin B1 receptor with des-Arg(10)-kallidin stimulated a rise in cytosolic Ca(2+) that was extracellular Na(+)-dependent and extracellular Ca(2+)-dependent. The des-Arg(10)-kallidin-stimulated increase of cytosolic Ca(2+) was blocked by KB-R7943, a specific inhibitor of Ca(2+) entry mode operation of the plasma membrane Na(+)/Ca(2+) exchanger. TGF-beta1 similarly stimulated a KB-R7943-sensitive increase of cytosolic Ca(2+) with kinetics distinct from the des-Arg(10)-kallidin-stimulated Ca(2+) response. We also found that KB-R7943 or 2',4'-dichlorobenzamil, an amiloride analog that inhibits the Na(+)/Ca(2+) exchanger activity, blocked the TGF-beta1- and des-Arg(10)-kallidin-stimulated increases of CTGF mRNA. Pretreatment with KB-R7943 also reduced the basal and TGF-beta1-stimulated levels of alpha1(I) collagen and alpha smooth muscle actin mRNAs. These data suggest that, in addition to regulating ion homeostasis, Na(+)/Ca(2+) exchanger acts as a signal transducer regulating CTGF, alpha1(I) collagen, and alpha smooth muscle actin expression. Consistent with a more widespread role for Na(+)/Ca(2+) exchanger in fibrogenesis, we also observed that KB-R7943 likewise blocked TGF-beta1-stimulated levels of CTGF mRNA in human microvascular endothelial and human osteoblast-like cells. We conclude that Ca(2+) entry mode operation of the Na(+)/Ca(2+) exchanger is required for des-Arg(10)-kallidin- and TGF-beta1-stimulated fibrogenesis and participates in the maintenance of the myofibroblast phenotype.
authors.affiliation: Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA. jromero@rics.bwh.harvard.edu
authors.forename: José R
authors.initials: JR
authors.lastname: Romero
authors.forename: Alicia
authors.initials: A
authors.lastname: Rivera
authors.forename: Vasco
authors.initials: V
authors.lastname: Lança
authors.forename: Manuel D P
authors.initials: MD
authors.lastname: Bicho
authors.forename: Paul R
authors.initials: PR
authors.lastname: Conlin
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Ricupero
mesh_terms: D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D055513:Connective Tissue Growth Factor; D003600:Cytosol / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis* / Q000737:chemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000737:chemistry; D007609:Kallidin / Q000031:analogs & derivatives* / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D008833:Microcirculation; D009206:Myocardium / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1
chemical_list: C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; C526317:CCN2 protein, human; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D055513:Connective Tissue Growth Factor; D007609:Kallidin; D012313:RNA; C052787:kallidin, des-Arg(10)-; D003094:Collagen; D008156:Luciferases; D013890:Thiourea; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium