Nucleocytoplasmic Transport in Skeletal Muscle

描述(申请人提供)：适当的骨骼肌功能依赖于卫星细胞中大量基因的激活和抑制，卫星细胞是组织特异性干细胞，以及多核收缩肌纤维。基因的表达在一定程度上是通过控制具有核功能的蛋白质的定位来调节的，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，因为改变核的输入或输出可能会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。细胞核和细胞质之间的大部分运输是由核孔复合体和核运输受体共同调节的，核运输受体识别货物蛋白并通过这些核孔调节运输。我们的长期目标是了解核运输机制在正常和衰老肌肉中的功能，以及它如何有助于基因表达的控制。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)的扰动改变了肌肉生理学。这项建议使用体外和体内互补的方法来探测卫星细胞和肌纤维中核质运输机制的不同组成部分，以获得对核运输的综合分析。因此，我们将询问卫星细胞中特定的核输入受体的功能(目标1)和特定核输入途径的选择性。 对于多核肌纤维的单个核(目标2)。此外，我们还将评估核孔洞 骨骼肌核对衰老和氧化应激反应的选择性(目标3)。了解骨骼肌中核质运输是如何调控的，将有助于更好地理解外部信号是如何被肌肉细胞感知并转化为组织内稳态所需的基因表达变化的。这些分析可能为预防因衰老、损伤或疾病造成的肌肉质量损失提供新的靶点。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新编程。

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.