Regulation of skeletal muscle protein degradation

描述（由申请人提供）： 这项研究计划的长期目标是提供一个全面的了解 细胞内蛋白质的生化机制和生理调节 降解细胞内蛋白质降解在决定净蛋白质中起着关键作用。 骨骼肌等组织的生长和萎缩。此外， 响应于收缩活动模式改变而发生的肌肉蛋白质组成， 这是由受调控的蛋白质降解引起的。哺乳动物细胞含有多种 用于降解其组成蛋白质的蛋白水解系统。相对角色和 这些系统在稳态下对细胞内蛋白质降解的贡献 条件和条件下改变蛋白质代谢，如发生在骨骼 人们对运动中的肌肉了解甚少，并且仍然是根本性的未解决问题， 肌肉生理学该计划项目补助金的研究单位将检查相对 两个主要的蛋白水解系统，泛素-蛋白酶体系统和钙蛋白酶系统， 在培养细胞中骨骼肌蛋白质的正常降解中。各功能 系统和每个系统中特定组件的相关功能将在 通过RNA干扰选择性抑制靶向组分的表达， 通过腺病毒感染使某些成分过度表达。这些治疗对 整体和肌原纤维蛋白降解速率，体外和体内蛋白酶活性， 细胞蛋白的泛素化，以及各种蛋白酶和 蛋白酶调节剂复合物，将被确定。最后，两种模式的影响，改变 收缩活动，慢性低频刺激运动神经和广泛的自愿 运行，对两种蛋白水解系统的水平和功能进行评价。这些 实验将提供重要的新的信息，基本的生化机制， 骨骼肌细胞内蛋白质降解，并确定如何功能和 蛋白水解系统的组成是由特定模式的收缩活动， 促进改变蛋白质降解的方式。

DESCRIPTION (Provided by applicant): The long-term objective of this research program is to provide a comprehensive understanding of the biochemical mechanisms and physiological regulation of intracellular protein degradation. Intracellular protein degradation plays a critical role in determining the net growth and atrophy of tissues, such as skeletal muscle. Moreover, qualitative changes in muscle protein composition that occur in response to altered patterns of contractile activity are brought about by regulated protein degradation. Mammalian cells contain multiple proteolytic systems for the degradation of their constituent proteins. The relative roles and contributions of these systems to the degradation of intracellular proteins under steady state conditions and under conditions of altered protein metabolism, such as occurred in skeletal muscles during exercise, are poorly understood and remain fundamental unresolved issues in muscle physiology. This research unit of the Program Project Grant will examine the relative roles of two major proteolytic systems, the ubiquitin-proteasome system and the calpain system, in the normal degradation of skeletal muscle proteins in cultured cells. Functions of each system and relative functions of specific components within each system will be examined after selective inhibition of expression of targeted components by RNA interference, and after overexpression of certain components by adenovirus infection. Effects of these treatments on rates of global and myofibrillar protein degradation, in vitro and in vivo protease activity, ubiquitination of cellular proteins, and the level and composition of various protease and protease-regulator complexes, will be determined. Finally, the effects of two models of altered contractile activity, chronic low-frequency stimulation of a motor nerve and extensive voluntary running, on the levels and function of the two proteolytic systems will be evaluated. These experiments will provide important new information about basic biochemical mechanisms of intracellular protein degradation in skeletal muscle, and define how the function and composition of proteolytic systems are regulated by specific patterns of contractile activity in a manner that promotes altered protein degradation.