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  • Ovid Technologies (Wolters Kluwer Health)  (2)
  • Tadevosyan, Artavazd  (2)
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  • Ovid Technologies (Wolters Kluwer Health)  (2)
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  • 1
    Online Resource
    Online Resource
    Transient Receptor Potential Canonical-3 Channel–Dependent Fibroblast Regulation in Atrial Fibrillation
    Ovid Technologies (Wolters Kluwer Health) ; 2012
    In:  Circulation Vol. 126, No. 17 ( 2012-10-23), p. 2051-2064
    Details
    In: Circulation, Ovid Technologies (Wolters Kluwer Health), Vol. 126, No. 17 ( 2012-10-23), p. 2051-2064
    Abstract: Fibroblast proliferation and differentiation are central in atrial fibrillation (AF)–promoting remodeling. Here, we investigated fibroblast regulation by Ca 2+ -permeable transient receptor potential canonical-3 (TRPC3) channels. Methods and Results— Freshly isolated rat cardiac fibroblasts abundantly expressed TRPC3 and had appreciable nonselective cation currents ( I NSC ) sensitive to a selective TPRC3 channel blocker, pyrazole-3 (3 μmol/L). Pyrazole-3 suppressed angiotensin II–induced Ca 2+ influx, proliferation, and α-smooth muscle actin protein expression in fibroblasts. Ca 2+ removal and TRPC3 blockade suppressed extracellular signal-regulated kinase phosphorylation, and extracellular signal-regulated kinase phosphorylation inhibition reduced fibroblast proliferation. TRPC3 expression was upregulated in atria from AF patients, goats with electrically maintained AF, and dogs with tachypacing-induced heart failure. TRPC3 knockdown (based on short hairpin RNA [shRNA]) decreased canine atrial fibroblast proliferation. In left atrial fibroblasts freshly isolated from dogs kept in AF for 1 week by atrial tachypacing, TRPC3 protein expression, currents, extracellular signal-regulated kinase phosphorylation, and extracellular matrix gene expression were all significantly increased. In cultured left atrial fibroblasts from AF dogs, proliferation rates, α-smooth muscle actin expression, and extracellular signal-regulated kinase phosphorylation were increased and were suppressed by pyrazole-3. MicroRNA-26 was downregulated in canine AF atria; experimental microRNA-26 knockdown reproduced AF-induced TRPC3 upregulation and fibroblast activation. MicroRNA-26 has NFAT (nuclear factor of activated T cells) binding sites in the 5′ promoter region. NFAT activation increased in AF fibroblasts, and NFAT negatively regulated microRNA-26 transcription. In vivo pyrazole-3 administration suppressed AF while decreasing fibroblast proliferation and extracellular matrix gene expression. Conclusions— TRPC3 channels regulate cardiac fibroblast proliferation and differentiation, likely by controlling the Ca 2+ influx that activates extracellular signal-regulated kinase signaling. AF increases TRPC3 channel expression by causing NFAT-mediated downregulation of microRNA-26 and causes TRPC3-dependent enhancement of fibroblast proliferation and differentiation. In vivo, TRPC3 blockade prevents AF substrate development in a dog model of electrically maintained AF. TRPC3 likely plays an important role in AF by promoting fibroblast pathophysiology and is a novel potential therapeutic target.
    Type of Medium: Online Resource
    ISSN: 0009-7322 , 1524-4539
    URL: Article
    DOI: 10.1161/CIRCULATIONAHA.112.121830
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2012
    detail.hit.zdb_id: 1466401-X
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  • 2
    Online Resource
    Online Resource
    Exchange Protein Directly Activated by cAMP Mediates Slow Delayed-Rectifier Current Remodeling by Sustained β-Adrenergic Activation in Guinea Pig Hearts
    Ovid Technologies (Wolters Kluwer Health) ; 2014
    In:  Circulation Research Vol. 114, No. 6 ( 2014-03-14), p. 993-1003
    Details
    In: Circulation Research, Ovid Technologies (Wolters Kluwer Health), Vol. 114, No. 6 ( 2014-03-14), p. 993-1003
    Abstract: β-Adrenoceptor activation contributes to sudden death risk in heart failure. Chronic β-adrenergic stimulation, as occurs in patients with heart failure, causes potentially arrhythmogenic reductions in slow delayed-rectifier K + current (I Ks ). Objective: To assess the molecular mechanisms of I Ks downregulation caused by chronic β-adrenergic activation, particularly the role of exchange protein directly activated by cAMP (Epac). Methods and Results: Isolated guinea pig left ventricular cardiomyocytes were incubated in primary culture and exposed to isoproterenol (1 μmol/L) or vehicle for 30 hours. Sustained isoproterenol exposure decreased I Ks density (whole cell patch clamp) by 58% ( P 〈 0.0001), with corresponding decreases in potassium voltage-gated channel subfamily E member 1 (KCNE1) mRNA and membrane protein expression (by 45% and 51%, respectively). Potassium voltage-gated channel, KQT-like subfamily, member 1 (KCNQ1) mRNA expression was unchanged. The β1-adrenoceptor antagonist 1-[2-((3-Carbamoyl-4-hydroxy)phenoxy)ethylamino]-3-[4-(1-methyl-4-trifluoromethyl-2-imidazolyl)phenoxy] -2-propanol dihydrochloride (CGP-20712A) prevented isoproterenol-induced I Ks downregulation, whereas the β 2 -antagonist ICI-118551 had no effect. The selective Epac activator 8-pCPT-2′-O-Me-cAMP decreased I Ks density to an extent similar to isoproterenol exposure, and adenoviral-mediated knockdown of Epac1 prevented isoproterenol-induced I Ks /KCNE1 downregulation. In contrast, protein kinase A inhibition with a cell-permeable highly selective peptide blocker did not affect I Ks downregulation. 1,2-Bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetate-AM acetoxymethyl ester (BAPTA-AM), cyclosporine, and inhibitor of nuclear factor of activated T cell (NFAT)-calcineurin association-6 (INCA6) prevented I Ks reduction by isoproterenol and INCA6 suppressed isoproterenol-induced KCNE1 downregulation, consistent with signal-transduction via the Ca 2+ /calcineurin/NFAT pathway. Isoproterenol induced nuclear NFATc3/c4 translocation (immunofluorescence), which was suppressed by Epac1 knockdown. Chronic in vivo administration of isoproterenol to guinea pigs reduced I Ks density and KCNE1 mRNA and protein expression while inducing cardiac dysfunction and action potential prolongation. Selective in vivo activation of Epac via sp-8-pCPT-2′-O-Me-cAMP infusion decreased I Ks density and KCNE1 mRNA/protein expression. Conclusions: Prolonged β 1 -adrenoceptor stimulation suppresses I Ks by downregulating KCNE1 mRNA and protein via Epac-mediated Ca 2+ /calcineurin/NFAT signaling. These results provide new insights into the molecular basis of K + channel remodeling under sustained adrenergic stimulation.
    Type of Medium: Online Resource
    ISSN: 0009-7330 , 1524-4571
    URL: Article
    DOI: 10.1161/CIRCRESAHA.113.302982
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2014
    detail.hit.zdb_id: 1467838-X
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