Nucleocytoplasmic Transport in Skeletal Muscle

描述（由申请人提供）：正常的骨骼肌功能依赖于卫星细胞（组织特异性干细胞）以及多核收缩肌纤维中许多基因的激活和抑制。基因表达部分通过控制具有核功能的蛋白质的定位来调节，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，因为改变核输入或输出可能导致异常的肌肉质量和功能。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。大多数细胞核和细胞质之间的转运是由核孔复合物介导的，核孔复合物与核转运受体协同作用，核转运受体识别货物蛋白并介导通过这些核孔的转运。我们的长期目标是了解正常和老化肌肉中核转运机制的功能，以及它如何有助于控制基因表达。根据我们的初步数据与已发表的文献，我们假设，在核转运机制（核输入受体和核孔）的扰动改变肌肉生理。该建议使用互补的体外和体内方法来探测卫星细胞和肌纤维中的核质转运机制的不同组分，以获得核转运的综合分析。因此，我们将询问卫星细胞中特定核输入受体的功能（Aim 1）和特定核输入途径的选择性 对于多核肌纤维的单个核（Aim 2）。此外，我们将评估核孔 骨骼肌细胞核对衰老和氧化应激反应的选择性（目的3）。了解核质运输在骨骼肌中的调节方式将有助于更好地理解肌肉细胞如何感知外部信号并将其转化为组织稳态所需的基因表达变化。这些分析可能为预防肌肉质量随衰老、损伤或疾病而损失提供新的靶点。此外，我们的分析可能会提高细胞治疗方法的效率，这些方法依赖于单个供体细胞与多核肌纤维的融合和核重编程。

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.