基于IRS-1 Tyr/Ser磷酸化失衡探讨芪地糖肾方干预糖尿病肾病足细胞自噬的机制

足细胞损伤导致的蛋白尿是糖尿病肾病(DN)进展的关键，适度自噬对足细胞保护至关重要。胰岛素受体底物1(IRS-1)酪氨酸(Tyr)或丝氨酸(Ser)磷酸残基化通过激活或抑制PI3K/Akt/mTOR信号通路，对自噬产生相反的作用。因此IRS-1Tyr/Ser磷酸化平衡在足细胞适度自噬中发挥重要作用。前期研究表明：芪地糖肾方可降低DN蛋白尿，减轻足细胞损伤。基于此我们提出芪地糖肾方通过恢复足细胞IRS-1Tyr/Ser磷酸化平衡，发挥调控细胞自噬，保护足细胞作用的假说。拟采用db/db自发2型DN小鼠和基因点突变阻断足细胞IRS-1Tyr或Ser磷酸化，模拟二者失衡状态，制备自噬激活或抑制细胞模型。从整体和细胞水平观察芪地糖肾方对IRS-1Tyr/Ser磷酸化平衡及其下游PI3K/Akt/mTOR信号通路和足细胞自噬的影响，以阐明芪地糖肾方足细胞保护作用机制，为临床防治DN蛋白尿提供新靶点。

Podocyte impairment induced proteinuria is the critical influencing factor of Diabetic Nephropathy (DN) progression. For podocyte protecting, moderate autophagy is of great importance. Insulin receptor substrate 1 (IRS-1) plays a important role in insulin signaling transduction. The phosphorylation of its tyrosine residues (Tyr) can suppress autophagy via activating the PI3K/Akt/mTOR signaling pathway. Conversely, its serine residues (Ser) are confirmed to promote the autophagy by preventing the PI3K/Akt/mTOR signaling pathway from activation. Thus, the balanced phosphorylation of IRS-1 Tyr/Ser contributes to moderate podocyte autophagy. Our previous studies have shown that Qi-Di-Tang-Shen formula can reduce proteinuria in DN patients and experimental rats, as well as alleviate podocyte impairment. Based on this, we presume that Qi-Di-Tang-Shen formula can regulate autophagy and reduce podocyte impairment by regaining the balance of IRS-1 Tyr/Ser phosphorylation and controlling downstream PI3K/Akt/mTOR signaling pathway. To verify the above hypothesis, we in order to utilizing specific gene mutation knock-in and plasmid transfection to create unbalanced situation of IRS-1 Tyr/Ser phosphorylation. Our study can clarifying the podocyte protection mechanism of Qi-Di-Tang-Shen formula. And provide a new target for DN treatment of traditional Chinese medicing.