SRSF1对骨骼肌卫星细胞增殖的调控研究

Skeletal muscle satellite cells are the muscle stem cells capable of self-renewal and proliferation, which are responsible for muscle growth through development and muscle repair after injury. Understanding their functional and regulatory mechanisms will help elucidate the role of satellite cells in muscle development and regeneration. Specific-inactivation of SRSF1 in skeletal muscle resulted in severe muscular dystrophy during postnatal development. Isolated single myofibers and in vitro culture assay showed that SRSF1 was only expressed in activated satellite cells and satellite cells lacking SRSF1 cannot proliferate as do the wildtype satellites. Here we plan to combine RNA-seq analysis with multiple molecular and cellular techniques to identifiy altentive splicing events controlled by SRSF1 and to explore the molecular mechanisms by which SRSF1 regulates proliferation of satellite cells. We also attempt to explore how SRSF1 and its alternative splicing events function during skeletal muscle growth and regeneration. These studies will provide a new paradigm with respect to the mechanism that underlies satellite cells in muscle growth, repair and regeneration.

骨骼肌卫星细胞是具有增殖和自我更新能力的成肌干细胞,是骨骼肌发育和修复再生过程中的核心。研究卫星细胞活化增殖的机制,对于理解卫星细胞在骨骼肌发育或再生中的生理功能具有重要的意义。我们前期研究发现，骨骼肌敲除SRSF1的小鼠表现为骨骼肌严重发育不良；基于单根肌纤维的卫星细胞体外培养实验则证明SRSF1蛋白只在活化、增殖的卫星细胞中表达，并且SRSF1的敲除导致卫星细胞体外丧失增殖能力。本研究拟通过高通量测序结合分子生物学和细胞生物学等多种试验手段，寻找和鉴定SRSF1调控的可变剪接，揭示SRSF1及其调控的可变剪接在卫星细胞增殖中的调控机制，阐明SRSF1及其调控的可变剪接在骨骼肌发育、修复和再生中的生理功能和分子机制。

骨骼肌组织的发育和维持是一个高度有序的过程，并在早期出生后阶段经历极其复杂的重构过程。虽然选择性剪接事件在骨骼肌发育和维持过程中的已有部分案例报道，但其详细的功能和分子机制尚不清楚。在此，我们首次报道了选择性剪接调控因子SRSF1不仅对于骨骼肌卫星细胞的增殖至关重要，而且紧密调控着神经肌肉接头的成熟和维持。我们观察到SRSF1的特异高表达在成肌细胞中，并且其表达模式与卫星细胞的激活和增殖息息相关。骨骼肌干细胞特异性敲除SRSF1引发严重的卫星细胞增殖障碍，以及小鼠个体水平上严重的骨骼肌生长不足症。此外，SRSF1缺失小鼠表现出乙酰胆碱受体集簇的弥散排布，呈现严重的神经肌肉接头障碍，因而表现出高度类似先天性重症肌无力疾病中出现的肌肉萎缩症状。最后，我们证明，SRSF1通过调控组织特异性剪接事件而参与骨骼肌的增长和功能维持。