title: Molecular mechanisms involved in the angiotensin-(1-7)/Mas signaling pathway in cardiomyocytes.
abstract: Recently there has been growing evidence suggesting that beneficial effects of angiotensin-(1-7) [Ang-(1-7)] in the heart are mediated by its receptor Mas. However, the signaling pathways involved in these effects in cardiomyocytes are unknown. Here, we investigated the involvement of the Ang-(1-7)/Mas axis in NO generation and Ca(2+) handling in adult ventricular myocytes using a combination of molecular biology, intracellular Ca(2+) imaging, and confocal microscopy. Acute Ang-(1-7) treatment (10 nmol/L) leads to NO production and activates endothelial NO synthase and Akt in cardiomyocytes. Ang-(1-7)-dependent NO raise was abolished by pretreatment with A-779 (1 micromol/L). To confirm that Ang-(1-7) action is mediated by Mas, we used cardiomyocytes isolated from Mas-deficient mice. In Mas-deficient cardiomyocytes, Ang-(1-7) failed to increase NO levels. Moreover, Mas-ablation was accompanied by significant alterations in the proteins involved in the regulation of endothelial NO synthase activity, indicating that endothelial NO synthase and its binding partners are important effectors of the Mas-mediated pathway in cardiomyocytes. We then investigated the role of the Ang-(1-7)/Mas axis on Ca(2+) signaling. Cardiomyocytes treated with 10 nmol/L of Ang-(1-7) did not show changes in Ca(2+)-transient parameters such as peak Ca(2+) transients and kinetics of decay. Nevertheless, cardiomyocytes from Mas-deficient mice presented reduced peak and slower [Ca(2+)](i) transients when compared with wild-type cardiomyocytes. Lower Ca(2+) ATPase of the sarcoplasmic reticulum expression levels accompanied the reduced Ca(2+) transient in Mas-deficient cardiomyocytes. Therefore, chronic Mas-deficiency leads to impaired Ca(2+) handling in cardiomyocytes. Collectively, these observations reveal a key role for the Ang-(1-7)/Mas axis as a modulator of cardiomyocyte function.
authors.affiliation: Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Marco F
authors.initials: MF
authors.lastname: Dias-Peixoto
authors.forename: Robson A S
authors.initials: RA
authors.lastname: Santos
authors.forename: Enéas R M
authors.initials: ER
authors.lastname: Gomes
authors.forename: Márcia N M
authors.initials: MN
authors.lastname: Alves
authors.forename: Pedro W M
authors.initials: PW
authors.lastname: Almeida
authors.forename: Leonardo
authors.initials: L
authors.lastname: Greco
authors.forename: Mariana
authors.initials: M
authors.lastname: Rosa
authors.forename: Beatrix
authors.initials: B
authors.lastname: Fauler
authors.forename: Michael
authors.initials: M
authors.lastname: Bader
authors.forename: Natalia
authors.initials: N
authors.lastname: Alenina
authors.forename: Silvia
authors.initials: S
authors.lastname: Guatimosim
mesh_terms: D000803:Angiotensin I / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D009569:Nitric Oxide; D000803:Angiotensin I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C118790:angiotensin I (1-7)