LonP1 regulates mitochondrial network remodeling through the PINK1/Parkin pathway during myoblast differentiation (Supplementary Table-1.docx)

Myoblast differentiation is a crucial process for myogenesis. Mitochondria function as an energy-providing machine that is critical to this process, and mitochondrial dysfunction can prevent myoblasts from fusing into myotubes. However, the molecular mechanisms underlying the dynamic regulation of mitochondrial networks remain poorly understood. In the present study, we found that the PTEN induced kinase 1(PINK1) /Parkin (an E3 ubiquitin-protein ligase) pathway is activated at the early stage of myoblast differentiation. Moreover, downregulation of mitofusin 2 (Mfn2) and increased dynamin-related protein 1 (Drp1) resulted in loosely formed mitochondria during this period. Furthermore, selective knockdown of the mitochondrial matrix protein Lon proteinase-1 (LonP1) at the early stage of myoblast differentiation induced mitochondrial depolarization and suppressed the PINK1/Parkin pathway and reduced Mfn2 and Drp1 levels, which blocked mitochondrial remodeling and myoblast differentiation. Overall, these data suggest that LonP1 plays an essential role in maintaining the normal myoblast differentiation process, which partly by regulating PINK1/Parkin mediated mitochondrial remodeling.成肌细胞分化是肌发生的关键过程。线粒体作为能量供给核心装置，对该过程至关重要，而线粒体功能障碍会阻碍成肌细胞融合为肌管。然而，线粒体网络动态调控的分子机制仍不甚明晰。 本研究发现，PTEN诱导激酶1（PTEN induced kinase 1，PINK1）/Parkin（一种E3泛素蛋白连接酶）通路在成肌细胞分化早期被激活。此外，该时期内线粒体融合蛋白2（mitofusin 2，Mfn2）表达下调、动力相关蛋白1（dynamin-related protein 1，Drp1）表达上调，导致线粒体结构松散。 进一步研究显示，在成肌细胞分化早期选择性敲低线粒体基质蛋白Lon蛋白酶-1（Lon proteinase-1，LonP1），可诱导线粒体去极化，抑制PINK1/Parkin通路，并降低Mfn2与Drp1的表达水平，进而阻断线粒体重塑与成肌细胞分化。 综上，本研究数据表明，LonP1在维持正常成肌细胞分化进程中发挥不可或缺的作用，其部分机制是通过调控PINK1/Parkin介导的线粒体重塑实现的。