PINK1/Parkin介导的线粒体自噬调控破骨细胞与根尖周骨破坏

Mitophagy is the selective degradation of mitochondria by autophagy. Evidence has recently arised regarding the essential role of PINK1/Parkin-mediated mitophagy in hematopoietic system-derived macrophages and dendritic cells-mediated immune function. However, the role and underlying mechanisms of PINK1/Parkin-mitophagy pathway in another distinct hematopoietic-derived cell, the osteoclast differentiation and function, remains unclear. Our preliminary data imply: Hyperactivation of PINK1/Parkin and mitophagy was present in periapical osteoclasts, which may be directly correlated with osteoclast differentiation and function. Thus, we proposed a new hypothetic model that PINK1/Parkin-mediated mitophagy regulates osteoclast and periapical bone destruction. Thus the thesis is devided into three main parts: Part one is in vivo experiment: PINK1/Parkin, mitophagy, and osteoclast-related factors are detected and measured in periapical tissues obtained as biopsy samples during periapical surgery, and in experimental periapical lesions of wildtype and Parkin knockout mice. Part two is to investigate the potential action of Mdivi-1 suppressing mitophagy to alleviate periapical bone destruction. Part three is in vitro experiment: Cultured osteoclasts are either treated with Mdivi-1, or genetically manipulated for Parkin knockout or overexpression, then its osteoclastogenic potential was analysed. Therefore, the present project may deepen molecular understanding of periapical bone destruction and comprehensively recognize the signaling control of osteoclast differentiation and function.

线粒体自噬是细胞通过自噬机制选择性清除异常或受损线粒体的过程。新发现PINK1/Parkin介导的线粒体自噬对造血系统来源巨噬细胞和树突状细胞免疫应答反应有重要作用。但其在另一独特造血源性细胞—破骨细胞中的调控效应尚不明确。我们前期研究发现小鼠根尖周病灶破骨细胞存在PINK1/Parkin高表达及线粒体自噬，可能与该细胞形成直接相关。本课题提出线粒体自噬调控破骨细胞及根尖周骨破坏的新假设：拟通过人病变组织、根尖周病动物模型和基因敲除小鼠等，检测PINK1/Parkin、线粒体自噬及破骨相关因子在根尖周病变不同阶段的动态变化；观察局部注射线粒体自噬阻断剂Mdivi-1对小鼠根尖周炎治疗效应；研究PINK1/Parkin信号干预下体外诱导破骨细胞过程中，线粒体自噬、分化及功能改变，以探讨其调控根尖周骨破坏的机理。本研究将对进一步阐明根尖周骨破坏机制和加深认识破骨细胞信号调控都具有重要意义。

线粒体自噬是细胞通过自噬的机制选择性清除异常或受损线粒体的过程。新发现PINK1/Parkin介导的线粒体自噬在造血系统来源巨噬细胞和树突状细胞的免疫应答反应中发挥重要作用。但其在另一独特造血源性细胞—破骨细胞中的调控效应及机理尚不明确。我们前期研究发现小鼠根尖周病灶破骨细胞存在PINK1/Parkin高表达及线粒体自噬发生，可能与该细胞分化和功能直接相关。本课题研究发现临床根尖病变标本中存在PINK1/Parkin/LC3/TOMM20的高表达；小鼠根尖周炎病损进展过程中，在破骨细胞中检测到PINK1/Parkin/LC3/TOMM20的高表达；体外破骨细胞分化过程中，PINK1/Parkin/LC3/TOMM20的表达逐渐增加，而线粒体自噬抑制剂Mdivi-1的干预显著抑制了破骨细胞的分化和骨吸收功能，同时伴随PINK1/Parkin/LC3/TOMM20的表达减弱；构建Parkin条件性敲除转基因小鼠，原代培养转基因小鼠骨髓来源单核巨噬细胞，发现其破骨细胞分化过程PINK1/Parkin/LC3/TOMM20的表达降低，MicroCT、TRAP染色结果表明基因敲除雄性小鼠股骨的骨密度显著高于对照组；合成载异甘草素的介孔硅，发现其可以显著抑制破骨细胞分化及小鼠颅盖骨炎性骨吸收。本系列研究将对进一步阐明根尖周骨破坏机制和加深认识破骨细胞信号调控都具有重要意义。