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：2016
卷号：113
期号：49
页码：E7976-E7985
DOI：10.1073/pnas.1617116113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceCalcium entry initiates contraction in cardiac myocytes, and altered expression of voltage-gated calcium channel 1.2 (CaV1.2) causes heart failure in mice. Here we show that reducing {beta}-adrenergic regulation of CaV1.2 by mutation of a PKA site in the C-terminal domain causes age-related heart failure. Dual mutation of a nearby casein-kinase II phosphorylation site accelerated heart failure. The PKA level was increased; PKA-mediated phosphorylation of ryanodine receptor type-2, phospholamban, and troponin-I was increased; the calcium pool in the sarcoplasmic reticulum was increased; and the activity of the calcium-dependent phosphoprotein phosphatase calcineurin was persistently elevated. These changes in mice with a mutation at the PKA site Ser1700 (SA mice) suggest that compensatory mechanisms may initially enhance contractility but eventually cause increased sensitivity to cardiovascular stress and heart failure. L-type Ca2+ currents conducted by voltage-gated calcium channel 1.2 (CaV1.2) initiate excitation-contraction coupling in the heart, and altered expression of CaV1.2 causes heart failure in mice. Here we show unexpectedly that reducing {beta}-adrenergic regulation of CaV1.2 channels by mutation of a single PKA site, Ser1700, in the proximal C-terminal domain causes reduced contractile function, cardiac hypertrophy, and heart failure without changes in expression, localization, or function of the CaV1.2 protein in the mutant mice (SA mice). These deficits were aggravated with aging. Dual mutation of Ser1700 and a nearby casein-kinase II site (Thr1704) caused accelerated hypertrophy, heart failure, and death in mice with these mutations (STAA mice). Cardiac hypertrophy was increased by voluntary exercise and by persistent {beta}-adrenergic stimulation. PKA expression was increased, and PKA sites Ser2808 in ryanodine receptor type-2, Ser16 in phospholamban, and Ser23/24 in troponin-I were hyperphosphorylated in SA mice, whereas phosphorylation of substrates for calcium/calmodulin-dependent protein kinase II was unchanged. The Ca2+ pool in the sarcoplasmic reticulum was increased, the activity of calcineurin was elevated, and calcineurin inhibitors improved contractility and ameliorated cardiac hypertrophy. Cardio-specific expression of the SA mutation also caused reduced contractility and hypertrophy. These results suggest engagement of compensatory mechanisms, which initially may enhance the contractility of individual myocytes but eventually contribute to an increased sensitivity to cardiovascular stress and to heart failure in vivo. Our results demonstrate that normal regulation of CaV1.2 channels by phosphorylation of Ser1700 in cardiomyocytes is required for cardiovascular homeostasis and normal physiological regulation in vivo.
