JLP调控肾小管上皮细胞自噬活化在肾脏纤维化中的作用和分子机制

Autophagy activation in tubular epithelial cells (TECs) is tightly associated with the progression of kidney fibrosis, to explore the regulatory mechanism of TECs autophagy activation is of great significance. Previous studies have shown that scaffold protein JLP is a potential inhibitor of autopahgy by mediating the transport of autophagy related molecules. Our group have found that JLP can negatively regulate the progression of kidney fibrosis, JLP is co-localized with Beclin-1 during kidney fibrosis and JLP deficiency exaggerated the activity of autophagy in TECs. Therefore, we proposed that JLP attenuates renal fibrosis by suppressing the activation of autophagy of TECs, the inhibitory effect of JLP in autophagy is related to regulation the function of Beclin-1. This project intends to use the JLP TECs-conditional knockout mice to verify the role of JLP in autophagy activation in TECs and fibrotic responses during kidney fibrosis; and to explore the molecular mechanism of JLP-mediated autophagy impairment in TECs from the perspective of Beclin-1 microtubule-ER transport in both animal and cell experiments. This project will reveal the molecular mechanism of the anti-fibrotic role of JLP during kidney fibrosis, and provide a theoretical evidence for serving JLP as a novel therapeutic target for treatment of kidney fibrosis.

肾小管上皮细胞（TECs）自噬活化与肾脏纤维化密切相关，深入探讨TECs自噬调控机制具有重要意义。近来研究显示，支架蛋白JLP可能通过介导自噬分子转运抑制自噬。本课题组既往发现JLP可拮抗肾脏纤维化反应，肾脏纤维化中JLP与Beclin-1存在共定位且JLP缺失可加重TECs自噬活性。因而我们推测：JLP通过抑制TECs自噬活化减轻肾脏纤维化反应，其自噬抑制效应与其调节Beclin-1功能有关。本项目拟应用TECs特异性JLP敲除小鼠，在动物和细胞实验上进一步验证JLP抑制TECs自噬活化及拮抗肾脏纤维化的作用，从Beclin-1微管-内质网转运角度解析JLP抑制自噬的机制。本研究将揭示JLP拮抗肾脏纤维化的新机制,为确立JLP作为逆转肾脏纤维化的新靶点提供科学依据。

架蛋白 JLP 是 JNK 连接蛋白（JNK-interacting protein, JIPs）家族中的重要一员，在常规细胞信号级联传导、免疫活化、轴突物质转运、细胞凋亡和自噬等多种生物学过程中发挥重要作用。我们前期的研究提示JLP可能是潜在的肾脏纤维化拮抗分子，但其具体作用及潜在分子作用机制仍有待进一步研究。本研究进一步探讨了JLP在肾脏纤维化是否通过调控肾小管上皮细胞（TECs）自噬活化来影响肾脏纤维化进展。通过构建TECs特异性JLP敲除及过表达转基因小鼠模型，我们发现TECs特异性JLP缺失显著促进 (UUO)所致肾间质纤维化损害，增加促纤维化因子TGF-β表达,且加重肾脏炎性细胞浸润和细胞凋亡，伴随有TECs自噬持续活化；相反地，TECs特异性JLP过表达改善了UUO诱导的肾脏间质纤维化进展，减少TGF-β表达并减轻炎性细胞浸润和小管细胞凋亡，且伴随着TECs自噬活化减弱。JLP siRNA可加重TGF-β诱导的小管细胞纤维化表型及自噬活化水平。通过不同药物及培养条件干预细胞自噬活化水平，我们发现JLP参与细胞自噬水平调控。综上所述，本研究发现JLP是重要的促肾脏纤维化分子，可能通过介导TECs自噬活性参与纤维化进展。