Myosin phosphorylation in skeletal muscle

骨骼肌中的肌球蛋白磷酸化

• 批准号: 6672950
• 负责人: JAMES T STULL
• 金额: $ 34.44万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6672950
• 关键词: biosensor device; calcium channel; calcium flux; calmodulin; cell line; exercise; genetically modified animals; laboratory mouse; muscle contraction; myoblasts; myosin light chain kinase; myosins; myotubes; phosphorylation; striated muscles; troponin

DESCRIPTION (provided by applicant): Myosin light chain kinase (MLCK) catalyzes the Ca2+/calmodulin-dependent phosphorylation of the regulatory light chain (RLC) of the motor protein, myosin II. There are two genes for MLCKs. One expresses smooth muscle MLCKs in all cells, including skeletal muscle fibers, whereas the other expresses a distinct skeletal muscle MLCK only in adult skeletal muscle fibers. Smooth muscle MLCK phosphorylates smooth and nonmuscle RLC but not skeletal muscle RLC. However, skeletal muscle MLCK readily phosphorylates all RLCs. In skeletal muscle Ca2+ activation of contraction is mediated through a thin filament regulatory system, troponin-tropomyosin. Recent reports indicate that Ca2+/calmodulin formation is low relative to the total cellular calmodulin and may be limiting for activation of multiple target proteins. Experiments in intact muscles show a correlation between RLC phosphorylation and post-tetanic potentiation of isometric force amplitude or treppe in fast-twitch skeletal muscles. The relative importance of RLC phosphorylation-force relationship is unclear due to modest increases in the rate and extent of force development in skinned fibers and to other factors affecting contractile performance in intact muscles including length-dependent effects on Ca2+ release from the sarcoplasmic reticulum, inter-myofilament spacing and calmodulin regulation of Ryr1, the calcium release channel. The research described in this application will determine (1) the relationship between the free Ca2+ concentration and Ca2+/ calmodulin formation in C2C12 myotubes and enzymatically dispersed mouse skeletal muscle fibers with biosensor molecules, (2) the temporal and spatial distributions of Ca2+/calmodulin binding to and activation of unique biosensor skeletal and smooth muscle MLCKs in skeletal muscle fibers from transgenic animals, and (3) if RLC phosphorylation and increased force amplitude are inhibited in fast-twitch skeletal muscle fibers from mice with ablation of the skeletal muscle MLCK gene. The results from these investigations will provide insights into Ca2+-dependent mechanisms recruited during exercise that enhance muscle performance.

描述（由申请人提供）： 肌球蛋白轻链激酶 (MLCK) 催化 Ca2+/钙调蛋白依赖性磷酸化 运动蛋白肌球蛋白 II 的调节轻链 (RLC)。有两个基因 MLCK。一种在所有细胞中表达平滑肌 MLCK，包括骨骼肌纤维， 而另一种仅在成人骨骼肌纤维中表达独特的骨骼肌 MLCK。平滑肌 MLCK 磷酸化平滑肌和非肌肉 RLC，但不磷酸化骨骼肌 RLC。然而，骨骼肌 MLCK 很容易磷酸化所有 RLC。 在骨骼肌中，Ca2+ 收缩的激活是通过细丝调节系统肌钙蛋白-原肌球蛋白介导的。最近的报告表明 Ca2+/钙调蛋白的形成较低 相对于总细胞钙调蛋白，可能限制多个靶点的激活 蛋白质。在完整肌肉中进行的实验表明，RLC 磷酸化与 强直后强直肌等长肌力幅度或快肌收缩力的增强。 由于适度的研究，RLC 磷酸化力关系的相对重要性尚不清楚。 皮纤维中力发展的速率和程度以及其他因素的增加 影响完整肌肉的收缩性能，包括长度依赖性影响 肌浆网、肌丝间距和钙调蛋白释放的 Ca2+ 调节钙释放通道 Ryr1。本申请中描述的研究将 确定（1）游离Ca2+浓度与Ca2+/钙调蛋白之间的关系 C2C12 肌管和酶促分散的小鼠骨骼肌纤维中的形成 生物传感器分子，(2) Ca2+/钙调蛋白结合的时间和空间分布 以及激活骨骼肌纤维中独特的生物传感器骨骼和平滑肌 MLCK 来自转基因动物，以及 (3) 如果 RLC 磷酸化和增加的力幅度是 通过骨骼肌消融，小鼠的快肌骨骼肌纤维受到抑制 MLCK 基因。这些研究的结果将提供对 Ca2+ 依赖性的深入了解 运动过程中招募的增强肌肉性能的机制。