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Endocytosis machinery is required for beta1-adrenergic receptor-induced hypertrophy in neonatal rat cardiac myocytes.

Authors: Morisco, C  Marrone, C  Galeotti, J  Shao, D  Vatner, DE  Vatner, SF  Sadoshima, J 
Citation: Morisco C, etal., Cardiovasc Res. 2008 Apr 1;78(1):36-44. Epub 2008 Jan 14.
Pubmed: (View Article at PubMed) PMID:18194989
DOI: Full-text: DOI:10.1093/cvr/cvn008

AIMS: Cardiac hypertrophy by activation of the beta-adrenergic receptor (beta AR) is mediated more efficiently by the beta1-AR than by the beta2-AR. We investigated the signalling mechanism by which the beta1-AR mediates cardiac hypertrophy. METHODS AND RESULTS: Experiments were performed in cultured neonatal rat cardiomyocytes. Hypertrophy was determined by the protein/DNA content and atrial natriuretic factor transcription. Phosphorylation of Akt and Src was assessed by immunoblotting. Isoproterenol (ISO, 10 microM), a non-selective beta-AR agonist, caused selective downregulation of the beta1-AR (control beta1 vs. beta2: 35 vs. 65%, Bmax 78 +/- 4 fmol/mg; 4 h, 10 vs. 90%, 61 +/- 5 fmol/mg). Concanavalin A (Con A, 0.5 microg/mL), an inhibitor of endocytosis, prevented downregulation of beta1-ARs by ISO treatment (4 h, 35 vs. 65%, 73 +/- 8 fmol/mg), suggesting that beta1-ARs selectively undergo endocytosis. Interference with beta1-AR endocytosis by Con A, carboxyl terminal peptide of beta-AR kinase-1, dominant negative (DN) beta-arrestin-1, or DN dynamin inhibited beta-adrenergic hypertrophy, suggesting that the endocytosis machinery plays a key role in mediating beta-adrenergic hypertrophy. Activation of Akt by the beta1-AR was blocked by inhibition of the endocytosis machinery, suggesting that endocytosis mediates activation of Akt. Akt plays a critical role in beta-adrenergic hypertrophy, since DN Akt blocked ISO-induced hypertrophy. beta-Adrenergic activation of Akt is mediated by Src, which associates with the endocytosis machinery and is necessary and sufficient to mediate beta-adrenergic hypertrophy. CONCLUSION: Activation of the endocytosis machinery is required for activation of Akt, which, in turn, critically mediates beta1-AR-induced cardiac hypertrophy.

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RGD Object Information
RGD ID: 5129139
Created: 2011-03-24
Species: All species
Last Modified: 2011-03-24
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.