title: A-kinase anchoring protein Lbc coordinates a p38 activating signaling complex controlling compensatory cardiac hypertrophy.
abstract: In response to stress, the heart undergoes a remodeling process associated with cardiac hypertrophy that eventually leads to heart failure. A-kinase anchoring proteins (AKAPs) have been shown to coordinate numerous prohypertrophic signaling pathways in cultured cardiomyocytes. However, it remains to be established whether AKAP-based signaling complexes control cardiac hypertrophy and remodeling in vivo. In the current study, we show that AKAP-Lbc assembles a signaling complex composed of the kinases PKN, MLTK, MKK3, and p38α that mediates the activation of p38 in cardiomyocytes in response to stress signals. To address the role of this complex in cardiac remodeling, we generated transgenic mice displaying cardiomyocyte-specific overexpression of a molecular inhibitor of the interaction between AKAP-Lbc and the p38-activating module. Our results indicate that disruption of the AKAP-Lbc/p38 signaling complex inhibits compensatory cardiomyocyte hypertrophy in response to aortic banding-induced pressure overload and promotes early cardiac dysfunction associated with increased myocardial apoptosis, stress gene activation, and ventricular dilation. Attenuation of hypertrophy results from a reduced protein synthesis capacity, as indicated by decreased phosphorylation of 4E-binding protein 1 and ribosomal protein S6. These results indicate that AKAP-Lbc enhances p38-mediated hypertrophic signaling in the heart in response to abrupt increases in the afterload.
authors.affiliation: Department of Pharmacology and Toxicology, Faculté de Biologie et Médecine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Irene
authors.initials: I
authors.lastname: Pérez López
authors.forename: Luca
authors.initials: L
authors.lastname: Cariolato
authors.forename: Darko
authors.initials: D
authors.lastname: Maric
authors.forename: Ludovic
authors.initials: L
authors.lastname: Gillet
authors.forename: Hugues
authors.initials: H
authors.lastname: Abriel
authors.forename: Dario
authors.initials: D
authors.lastname: Diviani
mesh_terms: D054758:A Kinase Anchor Proteins / Q000378:metabolism*; D000818:Animals; D006332:Cardiomegaly / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D018507:Gene Expression Regulation, Developmental; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D015778:Minor Histocompatibility Antigens; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D054758:A Kinase Anchor Proteins; C526201:Akap13 protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D015778:Minor Histocompatibility Antigens; C061570:protein kinase N; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D011493:Protein Kinase C; D048051:p38 Mitogen-Activated Protein Kinases