Caspase-mediated nuclear pore complex trimming in myogenesis and muscular dystrophies

项目总结/摘要 半胱天冬酶是一组蛋白酶，最众所周知的是它们在细胞凋亡中的破坏性作用。而他们的 在骨骼肌中，激活通常等同于细胞死亡，但这并不成立。例如在 在肌源性分化中，半胱天冬酶以瞬时、受调节和可逆的方式被激活。这些 蛋白酶也可在杜氏或肢带型肌营养不良症中被慢性激活。然而，非常 关于半胱天冬酶在肌肉形成和变性中的非凋亡作用知之甚少。通过关注 半胱天冬酶介导的修剪核孔复合物（NPC），这个K 01项目将阐明亚致死 半胱氨酸天冬氨酸蛋白酶导致了这种截然不同的结果。半胱天冬酶可以蛋白水解NPC的四个远端亚基， 损害核输出，并捕获几种含内斯（核输出信号）蛋白质，其中许多具有 基因组调控功能。在目标1中，在细胞核中积累的含NES的蛋白质在细胞核中表达。 肌生成和驱动基因组重构将以无偏的方式鉴定。此外，一个重点 将进行研究，以了解FAK，一种含有NES的粘着斑蛋白， 细胞核中的转录辅因子，与MBD 2（一种甲基CpG结合蛋白）相互作用， 基因.在目标2中，将评估营养不良肌肉中半胱天冬酶介导的NPC修整。鉴于这一谦虚 ER应激物激活半胱天冬酶足以引起NPC修剪和核输出关闭， 在肌管中，营养不良肌肉中的NPC将被类似地修饰和功能障碍。因此，蛋白质组- 将进行广泛的搜索以鉴定在营养不良的小鼠中其核水平异常高的蛋白质。 并有可能诱导基因组失调。 总之，通过解剖caspase-NPC-核输出轴的拮抗多效性， 旨在为新的治疗方法提供基础，促进肌肉健康， 个体和肌肉萎缩症患者。这项研究结合了Martin Hetzer实验室（ 索尔克研究所）在NPC和洛伦佐普里实验室（桑福德伯纳姆Prebys）在肌肉生物学。博士 Cho的长期目标是领导一个研究小组，研究核蛋白质组和蛋白酶， 肌生成和肌营养不良。K 01奖将为他提供稳定，网络机会， 有信心发展成为肌肉生物学领域的年轻领导者，精通还原论和 系统方法。

PROJECT SUMMARY/ABSTRACT Caspases are a group of proteases most well known for their destructive role in apoptosis. While their activation is often equated with cell death, in skeletal muscles, this does not hold true. For example, during myogenic differentiation, caspases are activated in a transient, regulated, and reversible manner. These proteases can also be activated chronically in Duchenne or limb-girdle muscular dystrophies. Nevertheless, very little is known about the non-apoptotic roles of caspases in muscle formation and degeneration. By focusing on caspase-mediated trimming of the nuclear pore complex (NPC), this K01 project will elucidate how sublethal caspases bring about such contrasting outcomes. Caspases can proteolyze four distal subunits of the NPC, impair nuclear export, and entrap several NES (nuclear export signal)-containing proteins, many of which have genome regulatory functions. In Aim 1, NES-containing proteins that accumulate in the nucleus during myogenesis and drive genome reconfiguration will be identified in an unbiased manner. In addition, a focused study will be conducted to understand how FAK, an NES-containing focal adhesion protein that doubles as a transcription cofactor in the nucleus, interacts with MBD2, a methyl CpG-binding protein, to de-repress myogenic genes. In Aim 2, caspase-mediated NPC trimming in dystrophic muscles will be assessed. Given that modest activation of caspases by ER stressors is sufficient to cause NPC trimming and nuclear export shutdown in myotubes, the NPC in dystrophic muscles will be similarly modified and dysfunctional. Therefore, a proteome- wide search will be performed to identify proteins whose nuclear levels are abnormally high in dystrophic myonuclei and have potential to induce genome dysregulation. In short, by dissecting the antagonistic pleiotropy of the caspase-NPC-nuclear export axis, this proposal aims to provide a foundation for new therapeutic approaches that promote muscular health in both healthy individuals and muscular dystrophy patients. This research combines the expertise of the Martin Hetzer lab (the Salk Institute) in the NPC and that of the Lorenzo Puri lab (Sanford-Burnham-Prebys) in muscle biology. Dr. Cho’s long-term goal is to lead a research group that studies nuclear proteome and proteases in the context of myogenesis and muscular dystrophies. K01 award will provide him the stability, networking opportunity, and confidence to develop into a young leader in the field of muscle biology who is proficient in both reductionist and systems approaches.