Reduced troponin I phosphorylation and increased Ca(2+)-dependent ATP-consumption in triton X-skinned fiber preparations from Galphaq overexpressor mice.
Mol Cell Biochem
; 314(1-2): 133-41, 2008 Jul.
Article
em En
| MEDLINE
| ID: mdl-18473122
ABSTRACT
Overexpression of the Galphaq-protein has been shown to result in hypertrophic and dilated cardiomyopathy. This study investigated Ca(2+ )sensitivity of tension and myosin-ATPase activity in skinned fiber preparations of male and female wildtype (WT; n = 12) and transgenic mice with a cardiac specific overexpression of the Galphaq-protein (Galphaq-OE; n = 11). In addition, the phosphorylation status of troponin I was measured. Ca(2+) sensitivity of tension was increased in Galphaq-OE with a significant reduction in the half-maximum Ca(2+) concentration (EC(50)) compared to WT. Similarly, Ca(2+) sensitivity of myosin ATPase activity was increased in Galphaq-OE when comparing Galphaq-OE to WT. Maximum Ca(2+)-dependent tension and ATPase activity were both enhanced in Galphaq-OE compared to WT littermates. Phosphorylation of troponin I was significantly reduced in Galphaq-OE compared to WT. In the above experiments, no gender specific differences were observed in either Gaq-OE or in WT. We conclude that, in mice, increased expression of the Galphaq-protein induces alterations of myofibrillar function and energy consumption, which are also characteristics of human heart failure. This may result from a decreased phosphorylation of troponin I in Galphaq-OE.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cálcio
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Octoxinol
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Fibras Musculares Esqueléticas
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Troponina I
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Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP
Limite:
Animals
Idioma:
En
Revista:
Mol Cell Biochem
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Alemanha