Increased expression of the auxiliary beta2-subunit of ventricular L-type Ca2+ channels leads to single-channel activity characteristic of heart failure

Hullin, Roger; Matthes, Jan; von Vietinghoff, Sibylle; Bodi, Ilona; Rubio, Marta; D'Souza, Karen; Friedrich Khan, Ismail; Rottländer, Dennis; Hoppe, Uta C; Mohacsi, Paul; Schmitteckert, Eva; Gilsbach, Ralf; Bünemann, Moritz; Hein, Lutz; Schwartz, Arnold; Herzig, Stefan (2007). Increased expression of the auxiliary beta2-subunit of ventricular L-type Ca2+ channels leads to single-channel activity characteristic of heart failure. PLoS ONE, 2(3), e292. Lawrence, Kans.: Public Library of Science 10.1371/journal.pone.0000292

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BACKGROUND: Increased activity of single ventricular L-type Ca(2+)-channels (L-VDCC) is a hallmark in human heart failure. Recent findings suggest differential modulation by several auxiliary beta-subunits as a possible explanation. METHODS AND RESULTS: By molecular and functional analyses of human and murine ventricles, we find that enhanced L-VDCC activity is accompanied by altered expression pattern of auxiliary L-VDCC beta-subunit gene products. In HEK293-cells we show differential modulation of single L-VDCC activity by coexpression of several human cardiac beta-subunits: Unlike beta(1) or beta(3) isoforms, beta(2a) and beta(2b) induce a high-activity channel behavior typical of failing myocytes. In accordance, beta(2)-subunit mRNA and protein are up-regulated in failing human myocardium. In a model of heart failure we find that mice overexpressing the human cardiac Ca(V)1.2 also reveal increased single-channel activity and sarcolemmal beta(2) expression when entering into the maladaptive stage of heart failure. Interestingly, these animals, when still young and non-failing ("Adaptive Phase"), reveal the opposite phenotype, viz: reduced single-channel activity accompanied by lowered beta(2) expression. Additional evidence for the cause-effect relationship between beta(2)-subunit expression and single L-VDCC activity is provided by newly engineered, double-transgenic mice bearing both constitutive Ca(V)1.2 and inducible beta(2) cardiac overexpression. Here in non-failing hearts induction of beta(2)-subunit overexpression mimicked the increase of single L-VDCC activity observed in murine and human chronic heart failure. CONCLUSIONS: Our study presents evidence of the pathobiochemical relevance of beta(2)-subunits for the electrophysiological phenotype of cardiac L-VDCC and thus provides an explanation for the single L-VDCC gating observed in human and murine heart failure.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Cardiovascular Disorders (DHGE) > Clinic of Cardiology
UniBE Contributor:	Hullin, Roger, Mohacsi, Paul
ISSN:	1932-6203
ISBN:	17356701
Publisher:	Public Library of Science
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:55
Last Modified:	05 Dec 2022 14:17
Publisher DOI:	10.1371/journal.pone.0000292
PubMed ID:	17356701
Web of Science ID:	000207444800015
URI:	https://boris.unibe.ch/id/eprint/23248 (FactScience: 40702)