DJ-1通过调节自噬在肝脏缺血再灌注损伤中的作用和分子机制研究

Liver ischemia-reperfusion injury (IRI) is one of the major obstacles in liver transplantation/hepatectomy.Our previous findings indicate that autophagy is suppressed during liver IRI and that increased autophagy could greatly protect liver from IRI. However the underlying mechanism by which autophagy is regulated under liver IRI is largely unknown. Our preliminary data demonstrate that DJ-1 level was significantly increased in the liver tissues undergoing IRI in WT mice, whereas remarkable resistance to IRI-induced hepatonecrosis and inhibition of autophagy was observed in DJ-1-/- mice. In addition, adminidtration of Chloroquine, an inhibitor of autophagy, can completely abolish the protection phenomenon caused by DJ-1 depletion. These findings strongly suggest that DJ-1 may affect IRI by modukating autophagy. Given that DJ-1 can negatively regulate PTEN’s level and activity and that PTEN can induce the production of PINK1, a key component in triggering type-2 mitotophay, we hypothesized that, by inhibiting PTEN, DJ-1 suppresses the type-2 mitophagy level during IRI and in turn execerbate IRI. To test our hypothesis, we will combine the in vivo liver IRI model with the in vitro hypoxia/reoxygenation model to further examine the protective role of DJ-1 depletion to liver IRI, dissect the underlying mechanism of how DJ-1 regulates autophagy in IRI, and evaluate the role of type-2 mitophagy in DJ-1 depletion mediated protection to IRI. This study may expand our understanding of the role of DJ-1 in the context of liver IRI, which may serve as a novel therapeutic strategy.

缺血再灌注损伤(IRI)是肝脏外科和肝移植的重要临床问题。我们之前研究发现IRI引起自噬抑制，而激活自噬可显著保护肝脏IRI，但IRI时自噬的调控机制尚不清楚。我们预实验发现IRI后WT小鼠肝脏中DJ-1表达显著升高，而DJ-1-/-小鼠对IRI引起的肝坏死及自噬抑制呈明显耐受，另外自噬抑制剂可消除DJ-1缺失对IRI的保护作用，提示DJ-1可能通过调控自噬影响IRI。鉴于DJ-1负向调控PTEN，而PTEN又能激活type2线粒体自噬关键基因PINK1，我们推测DJ-1通过抑制PTEN下调type2线粒体自噬水平从而影响IRI。本项目拟结合体内IRI小鼠模型及体外缺氧再供氧模型进一步：明确DJ-1缺失对肝脏IRI的保护作用，揭示DJ-1在IRI中调节自噬的分子机制，确立type2线粒体自噬在DJ-1缺失介导的IRI保护中的关键作用。本研究将可能为肝脏IRI的防治提供新的干预靶点。

缺血再灌注损伤(IRI)是肝脏外科和肝移植的重要临床问题，其中线粒体损伤是引起肝脏IRI的主要原因之一。我们以往研究发现肝脏IRI引起自噬抑制，而激活自噬可显著保护肝脏IRI，但肝脏IRI时自噬的调控机制尚不清楚。该项目中我们发现和证明了DJ-1通过调节线粒体自噬在肝脏IRI中起关键作用并作为一个潜在治疗肝脏IRI的靶点。通过本项目资助，我们发现临床IRI后的肝脏组织中DJ-1表达显著减少，并在小鼠肝脏缺血再灌注损伤模型及GEO数据库分析进一步证实了该研究结果。我们进一步通过DJ-1敲除小鼠及肝细胞特异性DJ-1敲除小鼠证明了DJ-1缺失对IRI具有显著的保护作用。发现在肝脏IRI中DJ-1缺失可显著增强肝细胞自噬，通过采用自噬抑制剂在体内外实验证明，DJ-1对肝脏IRI的调节依赖于其对肝细胞自噬的调节作用。深入的机制研究发现DJ-1主要是通过增强线粒体Parkin迁移进而增加线粒体自噬发挥对肝脏IRI的调节作用的。我们的研究结果基本验证了我们最初提出的在肝脏IRI中，DJ-1能通过调控线粒体自噬，增加肝脏损伤及炎症反应的假说。通过本项目资助，我们发表了系列研究成果，其中与项目直接相关的文章目前处于修稿中，基于该项目的资助我们对IRI的分子机制进行了深入研究，为治疗肝脏IRI提供了新靶点。