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）催化钙/钙调蛋白依赖性磷酸化 的调节轻链（RLC）的马达蛋白，肌球蛋白II。有两种基因 MLCK。一种在所有细胞中表达平滑肌MLCK，包括骨骼肌纤维， 而另一个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容易磷酸化所有RLC。 在骨骼肌中，Ca 2+激活收缩是通过细丝调节系统（肌钙蛋白-原肌球蛋白）介导的。最近的报道表明，Ca2 +/钙调素形成低， 相对于总的细胞钙调素， proteins.在完整肌肉中的实验显示RLC磷酸化和 强直后增强的等长力量的幅度或在快速收缩骨骼肌treppe。 RLC磷酸化力关系的相对重要性尚不清楚， 在剥皮纤维中力发展的速率和程度的增加以及其他因素 影响完整肌肉的收缩性能，包括对 肌浆网钙释放、肌丝间距和钙调蛋白 调节Ryr1，钙释放通道。本申请中描述的研究将 确定（1）游离Ca 2+浓度与Ca 2 +/钙调素之间的关系 在C2C12肌管和酶促分散的小鼠骨骼肌纤维中形成， 生物传感器分子，（2）时间和空间分布的Ca 2 +/钙调素结合， 以及骨骼肌纤维中独特的生物传感器骨骼肌和平滑肌MLCK的激活 从转基因动物，和（3）如果RLC磷酸化和增加的力的幅度是 在骨骼肌消融小鼠的快速收缩骨骼肌纤维中受到抑制 MLCK基因。这些研究的结果将为钙离子依赖性 在运动中增强肌肉表现的机制。