Role of phosphorylation in cardiac muscle myosin

磷酸化在心肌肌球蛋白中的作用

• 批准号: 9353147
• 负责人: James Sellers
• 金额: $ 12.91万
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9353147
• 关键词: ATP phosphohydrolase; Actinin; Actins; Actomyosin; Biological Assay; Calcium; Cardiac; Cardiac Myosins; Cardiovascular Diseases; Diabetes Mellitus; Endocardium; Failure; Family suidae; Goals; Heart Diseases; Heart failure; In Vitro; Infarction; Inherited; Kinetics; Length; Light; Measures; Mechanics; Molecular; Motor; Muscle; Myosin ATPase; Myosin Regulatory Light Chains; Phosphorylation; Play; Population; Property; Role; cell motility; non-muscle myosin; optical traps

Phosphorylation of the regulatory light chain of myosin (RLC) is altered in many forms of cardiac diseases, both inherited (HCM and DCM) and acquired (failure, infarction and diabetes). Phosphorylation of the RLC alters muscle mechanics by influencing calcium sensitivity, force, power and shortening velocity. Currently we do not understand how these effects on muscle are created at the molecular level of the cross-bridge. To this end, we isolated full-length cardiac myosin from porcine endocardium and altered its phosphorylation level in-vitro. We compare populations of myosins with complete (100%) RLC phosphorylation, intermediate phosphorylation (40% & 50%), and eradicated phosphorylation (0%). We could thereby correlate enzymatic and motility changes produced with RLC phosphorylation. We find that when myosin possesses 100% phosphorylated RLCs, the ATPase rate is accelerated and actin gliding velocities in putative unloaded and loaded (in presence of -actinin) conditions are accelerated. These results are consistent with the influence of RLC phosphorylation on the kinetics of the cross-bridge motor kinetics. RLC phosphorylation reduced the lifetime of actomyosin attachment as measured in the optical trap three-bead assay. These results suggest an important role for RLC phosphorylation in regulating the function of cardiac myosin. - The results are consistent with the hypothesis that reductions in normal levels of RLC phosphorylation may precipitate cardiovascular disorders and heart failure.

肌球蛋白调节轻链（RLC）的磷酸化在许多形式的心脏病中发生改变，包括遗传性（HCM和DCM）和获得性（衰竭、梗死和糖尿病）。RLC的磷酸化通过影响钙敏感性、力、功率和缩短速度来改变肌肉力学。目前我们还不知道这些对肌肉的影响是如何在分子水平上产生的。为此，我们从猪心内膜中分离出全长心肌肌球蛋白，并在体外改变其磷酸化水平。我们比较了完全（100%）RLC磷酸化、中间磷酸化（40%和50%）和完全磷酸化（0%）的肌球蛋白群体。因此，我们可以将RLC磷酸化产生的酶和运动性变化联系起来。我们发现，当肌凝蛋白拥有100%磷酸化的rlc时，ATPase速率加快，肌动蛋白在假定的卸载和加载（存在-肌动蛋白）条件下的滑动速度加快。这些结果与RLC磷酸化对过桥运动动力学的影响是一致的。RLC磷酸化减少了肌动球蛋白附着的寿命，这是在光学陷阱三头实验中测量的。这些结果提示RLC磷酸化在调节心肌肌球蛋白功能中起重要作用。-结果与RLC正常磷酸化水平的降低可能导致心血管疾病和心力衰竭的假设一致。