LAMTOR1调节的足细胞自噬在糖尿病肾病发病中的作用

Previous studies have found that reduced levels of autophagy induced by hyperglycemia in podocytes plays an important role in the pathogenesis of diabetic nephropathy (DN). Recently, our results demonstrated that LAMTOR1, a membrane protein specifically localized to the surface of late endosomes/lysosomes that serves as an anchor for the “Ragulator” complex, which regulates autophagy formation significantly upregulated in podocytes incubated by high glucose, however, its role is unknown. In this study, by gene recombination in vitro, this study is designed to, firstly, investigate that high glucose-induced upregulation of LAMTOR1 can cause the down-regulation of autophagy-related genes and the decrease of autophagy in podocytes, further resulted in the apoptosis and dysfunction of podocyte; secondly, to clarify whether the decrease of autophagy in podocytes was mediated by LAMTOR1 through mTORC1 activation and so on. In addition, Podocyte-specific LAMTOR1 knockout mice model will be used to observe whether LAMTOR1 activation can lead to diabetes glomerular filtration barrier damage, resulting in proteinuria; further, reveal that LAMTOR1 may be an effective target for the treatment of DN through intervention study. So far, So far, it is no report about the action of LAMTOR1 in the pathogenesis of glomerular filtration barrier damage in DN. It is believed that the novel findings would highlight the potential role of LAMTOR1 in the pathogenesis of DN. In summary, these results may provide scientific basis for the prevention and treatment of DN.

既往研究发现足细胞自噬水平降低在糖尿病肾病（DN）发生中发挥重要作用；最近，本课题组发现，一种可调节自噬形成的且特异性定位于晚期内涵体/溶酶体表面的膜蛋白LAMTOR1在高糖孵育的足细胞中显著上调，但其作用不明。为此，本课题运用基因重组技术，通过体外研究，首先揭示高糖诱导LAMTOR1上调可引起自噬相关基因下调，足细胞自噬减少，导致足细胞凋亡及功能异常；其次，阐明LAMTOR1调节足细胞自噬的分子机制与mTORC1活化等有关。另外，应用已经建立的特异性足细胞LAMTOR1基因敲除鼠模型，观察LAMTOR1活化可引起糖尿病肾脏-足细胞受损，导致蛋白尿；进一步以LAMTOR1为靶标进行干预，揭示LAMTOR1可能是DN治疗有效靶点。迄今，这些研究在国际上尚属空白，其预期的研究结果将丰富人们对DN肾小球滤过屏障受损发病机制认识，为DN的临床防治等提供理论和实验依据，具有重要的理论和现实意义。

本研究发现糖尿病小鼠肾脏及高糖处理的人足细胞LAMTOR1表达显著升高同时伴随肾小球足突融合、变宽和肾小球基底膜增厚肾间质纤维化。高糖情况下，细胞内LAMTOR1表达升高及自噬通路的激活影响足细胞凋亡。敲除LAMTOR1表达能够逆转高糖引起的细胞凋亡。此外，高糖情况下，巨噬细胞内LAMTOR1表达升高能促进其产生和分泌TGF-β从而促进足细胞凋亡。LAMTOR1肾脏敲除后，糖尿病模型中小鼠肾脏纤维化、细胞凋亡情况显著改善。