title: Connective tissue growth factor/CCN2 attenuates β-adrenergic receptor responsiveness and cardiotoxicity by induction of G protein-coupled receptor kinase-5 in cardiomyocytes.
abstract: Myocardial connective tissue growth factor (CTGF/CCN2) is induced in heart failure, a condition associated with diminution of β-adrenergic receptor (β-AR) responsiveness. Accordingly, we aimed to investigate whether CTGF could play a mechanistic role in regulation of β-AR responsiveness. Concentration-response curves of isoproterenol-stimulated cAMP generation in cardiomyocytes from transgenic mice with cardiac-restricted overexpression of CTGF (Tg-CTGF) or cardiomyocytes pretreated with recombinant human CTGF (rec-hCTGF) revealed marked reduction of both β₁-AR and β₂-AR responsiveness. Consistently, ventricular muscle strips from Tg-CTGF mice stimulated with isoproterenol displayed attenuation of maximal inotropic responses. However, no differences of maximal inotropic responses of myocardial fibers from Tg-CTGF mice and nontransgenic littermate control (NLC) mice were discerned when stimulated with supramaximal concentrations of dibutyryl-cAMP, indicating preserved downstream responsiveness to cAMP. Congruent with a mechanism of desensitization of β-ARs, mRNA and protein levels of G protein-coupled receptor kinase 5 (GRK5) were found isoform-selective upregulated in both cardiomyocytes from Tg-CTGF mice and cardiomyocytes exposed to rec-hCTGF. Corroborating a mechanism of GRK5 in CTGF-mediated control of β-AR sensitivity, Chinese hamster ovary cells pretreated with rec-hCTGF displayed increased agonist- and biased ligand-stimulated β-arrestin binding to β-ARs. Despite increased sensitivity of cardiomyocytes from GRK5-knockout (KO) mice to β-adrenergic agonists, pretreatment of GRK5-KO cardiomyocytes with rec-hCTGF, as opposed to cardiomyocytes from wild-type mice, did not alter β-AR responsiveness. Finally, Tg-CTGF mice subjected to chronic exposure (14 days) to isoproterenol revealed blunted myocardial hypertrophy and preserved cardiac function versus NLC mice. In conclusion, this study uncovers a novel mechanism controlling β-AR responsiveness in cardiomyocytes involving CTGF-mediated regulation of GRK5.
authors.affiliation: Institute for Surgical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Gravning
authors.forename: M Shakil
authors.initials: MS
authors.lastname: Ahmed
authors.forename: Eirik
authors.initials: E
authors.lastname: Qvigstad
authors.forename: Kurt
authors.initials: K
authors.lastname: Krobert
authors.forename: Thor
authors.initials: T
authors.lastname: Edvardsen
authors.forename: Ingvild Tronstad
authors.initials: IT
authors.lastname: Moe
authors.forename: Else Marie V
authors.initials: EM
authors.lastname: Hagelin
authors.forename: Julia
authors.initials: J
authors.lastname: Sagave
authors.forename: Guro
authors.initials: G
authors.lastname: Valen
authors.forename: Finn Olav
authors.initials: FO
authors.lastname: Levy
authors.forename: Jan-Bjørn
authors.initials: JB
authors.lastname: Osnes
authors.forename: Tor
authors.initials: T
authors.lastname: Skomedal
authors.forename: Håvard
authors.initials: H
authors.lastname: Attramadal
mesh_terms: D000322:Adrenergic Agonists / Q000494:pharmacology; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D006332:Cardiomegaly / Q000139:chemically induced; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D054774:G-Protein-Coupled Receptor Kinase 5 / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000633:toxicity*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D000071557:beta-Arrestins; D000099211:Phospholamban
chemical_list: D000322:Adrenergic Agonists; D019390:Arrestins; D002135:Calcium-Binding Proteins; D055513:Connective Tissue Growth Factor; D054774:G-Protein-Coupled Receptor Kinase 5; D007545:Isoproterenol; D010750:Phosphoproteins; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D011994:Recombinant Proteins; D000071557:beta-Arrestins; D000099211:Phospholamban