CALMODULIN-DEPENDENT PROTEIN KINASE II IN HEART CALCIUM CHANNEL REGULATION

钙离子通过电压依赖性钙通道的内流在心脏中很重要 血管肌肉兴奋收缩偶联。钙离子的调节作用 多功能蛋白激酶、钙/钙调素依赖性蛋白激酶II (CaMKII)在神经细胞的信号转导中起着非常重要的作用。 系统，如长时程增强(LTP)和记忆。然而，小我 已知这种蛋白激酶是否也调节 心肌细胞。我们的研究表明，在空间分辨率和 钙通道阻滞剂CaMKII对L型钙通道电流的新效应 (ICA)在心肌细胞中。单独去极化或钙离子内流都可以 增加ICA波幅，减缓ICA失活。不同的伏特 E- 钙依赖效应持续存在，时间常数约为1.7%，S和 9 S。这两种影响都被一种特定的 CaMKII的多肽抑制剂。这种CaMKII抑制剂还能抑制 去极化保持电位引起的ICa延长。安特卫普 针对自磷酸化(激活)的CaMKII，PY-66是定位的 靠近肌膜，CaMKII激活的轮廓是 与不同条件下ICA的变化定性相关。 因此，CaMKII对ICa的作用受膜的双重调节 去极化和钙内流：后者直接激活CaMKII 而前者可能促进了本构CaMKI之间的相互作用 以及膜通道蛋白。与活跃的CaMKII相反 CaMKII总酶的胞内分布 (通过使用与CaMKII k特异反应的抗体进行可视化 异构体)，但没有感觉到它的激活状态与更高的 核子分布。这表明CaMKII被转移到细胞内 心肌细胞激活后的肌膜。这些调查结果提供了 对理解血管内皮细胞的生理功能的新见解 心肌细胞中普遍存在的蛋白激酶，CaMKII可能在 其他类型的细胞也是如此。

Ca2+ entry through voltage-dependent Ca2+ channels is important in cardiac and vascular muscle excitation-contraction coupling. The Ca2+ regulated multifunctional protein kinase, Ca2+/calmodulin-dependent protein kinase II (CaMKII), has a very important role in signal transduction in nervous system, such as long-term potentiation (LTP) and memory. However, little i known as to whether this protein kinase also modulates the function of cardiac cells. Our studies demonstrate both spatially resolved and temporally distinct novel effects of CaMKII on L-type Ca2+ channel current (ICa) in cardiac cells. Either depolarization alone or calcium influx can increase the amplitude and slow the inactivation of ICa. The distinct volt e- and Ca2+-dependent effects persist with time constants of about 1.7 s and 9 s, respectively. Both effects are completely abolished by a specific peptide inhibitor of CaMKII. This CaMKII inhibitor also suppresses the prolongation of ICa induced by depolarizing holding potentials. An antibod specific for the autophosphorylated (activated) CaMKII, PY-66, is localized close to sarcolemmal membranes and the profile of CaMKII activation is qualitatively correlated with the changes in ICa under various conditions. Thus, the action of CaMKII on ICa is dually regulated by membrane depolarization and by calcium influx: the latter directly activates CaMKII while the former likely promotes the interaction between constitutive CaMKI and the membrane channel proteins. In contrast to the active CaMKII distribution, the intracellular distribution of the total CaMKII enzyme (visualized by using an antibody which specifically reacts with CaMKII k isoform) but does not sense its activation state is uniform with a higher nuclear distribution. This suggests that CaMKII is translocated to the cel sarcolemma following activation in cardiac myocytes. These findings provid new insights toward understanding the physiological function of the ubiquitous protein kinase, CaMKII in cardiac muscle cells as possibly in other type of cells as well.