Increased expression of the auxiliary beta(2)-subunit of ventricular L-type Ca(2)+ channels leads to single-channel activity characteristic of heart failure.
PLoS One
; 2(3): e292, 2007 Mar 14.
Article
in En
| MEDLINE
| ID: mdl-17356701
ABSTRACT
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 ANDRESULTS:
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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Calcium Channels, L-Type
/
Heart Failure
/
Heart Ventricles
Type of study:
Prognostic_studies
Limits:
Animals
/
Humans
Language:
En
Journal:
PLoS One
Journal subject:
CIENCIA
/
MEDICINA
Year:
2007
Document type:
Article
Affiliation country:
Switzerland