Roles of Myosin Light Chain Kinases in the Heart

肌球蛋白轻链激酶在心脏中的作用

• 批准号: 7564721
• 负责人: JAMES T STULL
• 金额: $ 38.11万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7564721
• 关键词: Ablation; Actins; Affect; Biochemical; Biosensor; Birth; Breeding; Calcium; Calmodulin; Cardiac; Cardiac Myocytes; Cardiac Myosins; Cardiomyopathies; Catheterization; Cells; Congestive Heart Failure; Consensus; Data; Defect; Development; Echocardiography; Embryonic Heart; Fiber; Fluorescence Resonance Energy Transfer; Genes; Heart; Heart Atrium; Heart Hypertrophy; Histology; Investigation; Knock-out; Knockout Mice; Lead; Left; Length; Light; Measurement; Measures; Mus; Muscle Cells; Myocardium; Myosin ATPase; Myosin Light Chain Kinase; Myosin Light Chains; Myosin Type II; Newborn Infant; Nonmuscle Myosin Type IIB; Performance; Phosphorylation; Phosphotransferases; Physiological; Play; Procedures; Property; Protein Isoforms; Proteins; Regulation; Research; Role; Sarcomeres; Skeletal Muscle Myosins; Skin; Stress; Structure; Testing; Thick Filament; Tissues; Transgenic Mice; Transgenic Organisms; Transmission Electron Microscopy; Ventricular; Weight; base; fiber cell; gain of function; in vivo; indexing; insight; knockout animal; knockout gene; novel; overexpression; response

Contraction of heart muscle results from the cyclic interaction of myosin with actin under the regulation of sarcomeric thin and thick filament proteins. Based on results from skinned fibers and cells in culture it has been proposed that phosphorylation of the regulatory light chain (RLC) of sarcomeric myosin plays a role in enhancing ventricular contraction while phosphorylation of either sarcomeric or cytoplasmic myosin-IIB promotes sarcomere assembly. Functional changes in the expression and activity of Ca2+/calmodulin- dependent myosin light chain kinase (MLCK) may lead to cardiomyopathy. Although cardiac myocytes contain smooth (sm) muscle MLCK, it is not clear that this is the only kinase responsible for RLC phosphorylations. We propose to identify the kinase that phosphorylates the respective RLCs in addition to physiological roles for RLC phosphorylations in cardiac contraction and sarcomere assembly. Specific Aim 1. Determine effects of overexpression and knockout of smMLCK in ventricular and atrial myocytes. Transgenic mice will be made with MLCK expressed specifically in cardiac myocytes. The gene for smooth muscle MLCK will be ablated by crossing mice with the floxed smooth muscle MLCK gene and mice expressing Cre specifically in cardiac myocytes. Other kinases that phosphorylate RLC will be identified. RLC phosphorylations will be measured in cardiac tissues as well as isolated myocytes. Specific Aim 2. Determine if functional consequences are associated with changes in expression of MLCK isoforms. Anatomical properties of hearts from transgenic and knockout mice will be assessed. Functional properties including contractile indices will be measured in perfused hearts and in vivo by invasive and noninvasive measurements. Responsiveness to stresses that lead to cardiac hypertrophy will also be evaluated. Specific Aim 3. Determine if sarcomere assembly is affected by overexpression or knockout of smMLCK. Sarcomere formation in response to hypertrophic agents will be measured in myocytes from newborn transgenic or knockout mice. Morphometric analyses will be combined with RLC phosphorylation measurements. Development of myofibrillar structure will be examined in hearts from embryonic knockout mice. Results from these studies will provide novel biochemical insights into the physiological regulation and functional importance of cardiac myosin light chain phosphorylation.

心肌收缩是肌凝蛋白与肌动蛋白循环相互作用的结果