丝氨酸蛋白酶活化蛋白C通过整合素β3调控PI3K p85-sXBP1信号通路减轻肾脏缺血-再灌注损伤的机制研究

Ischemia-reperfusion injury (IRI) is one of the most common kidney diseases in clinical medicine. It is harmful to human health and the consequences of renal IRI can be dramatic, resulting in a marked decline of renal function and high mortality rates. A number of candidate mechanisms involved in renal IRI have been identified in preclinical studies, but the complicated pathogenesis is not fully understood as yet. Some research has shown that endoplasmic reticulum stress (ERS) can be closely correlated with renal IRI. Our preliminary data demonstrated that the serine protease activated protein C (aPC) could be a key regulator both in anti-coagulation and anti-inflammation, it also could play an important role in protecting against renal IRI. However, the underlying mechanism by which aPC regulates ERS remains unknown. Further studies conclusively showed that there are Arginine-Glycine-Aspartate-containing (RGD) three peptides in the sequence of aPC, then aPC could specifically combine with integrin β3 and regulate the phosphatidylinositol 3-kinase (PI3K) signaling pathway. Remarkably, aPC could induce complex formation of p85α/p85β with spliced X box binding protein 1 (sXBP1) and promote nuclear translocation of sXBP1 via heterodimerization with p85α/p85β. Recombinant variants of aPC, such as the 3K3A-aPC (Lys191-193Ala) mutant, which specifically reduced anticoagulant activity, engineered to reduce aPC-associated bleeding risk while retaining normal cell-signaling activity, have shown the same benefits in renal IRI. Therefore, we formulate a hypothesis that aPC could ameliorate renal IRI by regulating PI3K p85-sXBP1 signaling pathway through integrin β3, the nephroprotective effect of aPC in IRI is independent of its anticoagulant function. This study will investigate the effect and elucidate the molecular mechanism of aPC on the regulation of ERS in vivo and in vitro, for providing new idea and theoretical evidence for the treatment of renal IRI.

缺血再灌注损伤是临床肾脏常见的病变之一，其复杂的致病机理尚未完全阐明。有研究显示，内质网应激与肾缺血再灌注损伤密切相关。我们前期研究表明，丝氨酸蛋白酶活化蛋白C（aPC）在减轻肾缺血再灌注损伤中发挥了重要作用，但其调控内质网应激的作用机制仍不明确。进一步研究发现，aPC具有与整合素结合的精氨酸-甘氨酸-天冬氨酸（RGD）三肽序列，其与整合素β3结合后能促进内质网应激相关的磷脂酰肌醇3-激酶（PI3K）信号通路中p85蛋白与剪接的X盒结合蛋白1（sXBP1）相结合而产生保护效应，且其无抗凝血功能的突变体3K3A-aPC具有相同的功效。由此我们假设，aPC是通过整合素β3调控PI3K p85-sXBP1信号通路抑制内质网应激而减轻肾缺血再灌注损伤的，其保护效应与抗凝血功能无关。本项目拟从体内、体外两个水平探讨aPC调控内质网应激的分子机制，为防治肾缺血再灌注损伤提供新的研究思路和理论依据。

缺血再灌注损伤是临床上导致肾脏病变的常见原因之一，严重危害人类健康。因此研究阐明其复杂的致病机理，探寻有效的治疗保护手段，对改善病人预后具有非常重要的临床意义。本研究从体内、体外两个水平均发现凝血系统中的丝氨酸蛋白酶活化蛋白C（aPC）在减轻肾脏缺血再灌注损伤中发挥了重要作用，其通过整合素β3受体调控磷脂酰肌醇3-激酶（PI3K）信号通路中p85蛋白与剪接的X盒结合蛋白1（sXBP1）相结合，抑制内质网应激从而产生保护性效应，且该保护作用与抗凝血功能无关。本研究为防治肾脏缺血再灌注损伤提供了新的研究思路和理论依据。