Nucleocytoplasmic Transport in Skeletal Muscle

描述（由申请人提供）：适当的骨骼肌功能依赖于卫星细胞中许多基因的激活和抑制，卫星细胞是组织特异性干细胞，以及多核收缩肌纤维。基因表达部分是通过控制具有核功能的蛋白质的定位来调节的，例如转录因子和染色质重塑酶。这些核蛋白的亚细胞定位必须严格控制，因为核输入或输出的改变可能导致肌肉质量和功能的异常。关键的核调节蛋白如何进入卫星细胞和肌纤维的细胞核尚不清楚。大多数核和细胞质之间的运输是由核孔复合物和核转运受体介导的，核转运受体识别货物蛋白并介导通过这些核孔的运输。我们的长期目标是了解核转运机制在正常和衰老肌肉中的功能，以及它如何有助于控制基因表达。根据我们的初步数据和已发表的文献，我们假设核运输机制（核输入受体和核孔）的扰动会改变肌肉生理。本研究采用互补的体外和体内方法来探索卫星细胞和肌纤维中核细胞质运输机制的不同组成部分，以获得核运输的综合分析。因此，我们将研究卫星细胞中特定核输入受体的功能（目的1）和特定核输入途径的选择性

DESCRIPTION (provided by applicant): Proper skeletal muscle function is dependent on activation and repression of numerous genes in satellite cells, which are tissue-specific stem cells, as well as in multinucleated contractile myofibers. Gene expression is regulated in part by controlling the localization of proteins with nuclear functions, such as transcription factors and chromatin remodeling enzymes. The subcellular localization of these nuclear proteins must be tightly controlled because altered nuclear import or export could result in aberrant muscle mass and function. How key nuclear regulatory proteins gain access to nuclei in satellite cells and myofibers is unknown. Most transport between the nucleus and the cytoplasm is mediated by nuclear pore complexes in concert with nuclear transport receptors that recognize cargo proteins and mediate transport through these nuclear pores. Our long-term goal is to understand the function of the nuclear transport machinery in normal and aged muscle and how it contributes to control of gene expression. Based on our preliminary data together with published literature, we hypothesize that perturbations in the nuclear transport machinery (nuclear import receptors and nuclear pores) alter muscle physiology. This proposal uses complementary in vitro and in vivo approaches to probe different components of the nucleocytoplasmic transport machinery in satellite cells and myofibers in order to obtain an integrated analysis of nuclear transport. Thus, we will interrogate the function of specific nuclea import receptors in satellite cells (Aim 1) and the selectivity of specific nuclear import pathways for individual nuclei of multinucleated myofibers (Aim 2). In addition, we will assess nuclear pore selectivity in skeletal muscle nuclei in response to aging and oxidative stress (Aim 3). Understanding how nucleocytoplasmic transport is regulated in skeletal muscle will lead to a greater understanding of how external signals are sensed by muscle cells and translated into changes in gene expression necessary for tissue homeostasis. These analyses may provide new targets for preventing loss of muscle mass with aging, injury, or disease. In addition, our analyses may enhance the efficiency of cell therapeutic approaches that rely on fusion and nuclear reprogramming of individual donor cells with multinucleated myofibers.