标题：Transient cardiac expression of constitutively active Gαq leads to hypertrophy and dilated cardiomyopathy by calcineurin-dependent and independent pathways
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：23
页码：13893-13898
DOI：10.1073/pnas.95.23.13893
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Cardiac hypertrophy and dilatation can result from stimulation of signal transduction pathways mediated by heterotrimeric G proteins, especially Gq, whose subunit activates phospholipase C{beta} (PLC{beta}). We now report that transient, modest expression of a hemagglutinin (HA) epitope-tagged, constitutively active mutant of the Gq subunit (HA*q) in hearts of transgenic mice is sufficient to induce cardiac hypertrophy and dilatation that continue to progress after the initiating stimulus becomes undetectable. At 2 weeks, HA*q protein is expressed at less than 50% of endogenous q/11, and the transgenic hearts are essentially normal morphologically. Although HA*q protein declines at 4 weeks and is undetectable by 10 weeks, the animals develop cardiac hypertrophy and dilatation and die between 8 and 30 weeks in heart failure. As the pathology develops, endogenous q/11 rises (2.9-fold in atria; 1.8-fold in ventricles). At 2 weeks, basal PLC activity is increased 9- to 10-fold in atria but not ventricles. By 10 weeks, it is elevated in both, presumably because of the rise in endogenous q/11. We conclude that the pathological changes initiated by early, transient HA*q expression are maintained in part by compensatory changes in signal transduction and other pathways. Cyclosporin A (CsA) prevents hypertrophy caused by activation of calcineurin [Molkentin, J. D., Lu, J.-R., Antos, C. L., Markham, B., Richardson, J., Robbins, J., Grant, S. R. & Olson, E. N. (1998) Cell 93, 215-228]. Because HA*q acts upstream of calcineurin, we hypothesized that HA*q might initiate additional pathways leading to hypertrophy and dilatation. Treating HA*q mice with CsA diminished some, but not all, aspects of the hypertrophic phenotype, suggesting that multiple pathways are involved.
