Podocyte injury plays an important role in diabetic nephropathy (DN), and apoptosis is one of its mechanisms. The transient receptor potential channel 6 (TRPC6) is expressed in podocytes and mediates podocyte injury induced by high glucose levels. Tacrolimus is a novel immunosuppressive agent that is reported to play an important role in podocyte protection. The purpose of this study was to investigate the potential mechanism of podocyte protection by tacrolimus in a type 2 diabetic mellitus (T2DM) rat model and in immortalized mouse podocytes (MPC5). Transmission electron microcopy was used to evaluate renal injury morphology. After treatment with FK506, we measured 24-hour urinary albumin-to-creatinine ratios and creatinine clearance rates as well as major biochemical parameters such as glucose, insulin, serum creatinine, urea nitrogen, total cholesterol, triglycerides, alanine transaminase, and aspartate aminotransferase. Nephrin and TRPC6 protein expression and podocyte apoptotic rates in vivo and in vitro were measured using immunohistochemical staining, TUNEL assays, and flow cytometry, respectively. Western blot was used to measure expression of cleaved-caspase-3 and bax/bcl-2. Exposed to high glucose (HG), DM rats exhibited disrupted biochemical conditions and impaired podocyte structure. Decreased expression of nephrin and increased expression of TRPC6, cleaved-caspase-3, and bax/bcl-2 ratios were found in podocytes, along with higher apoptotic percentage, while tacrolimus intervention counteracted the effect of HG on podocytes. Our results suggest that tacrolimus protects podocytes during the progression of type 2 diabetic nephropathy, possibly ameliorating podocyte apoptosis by downregulating the expression of TRPC6.

中文翻译：

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他克莫司通过下调 TRPC6 在糖尿病肾病中保护足细胞免于凋亡

足细胞损伤在糖尿病肾病（DN）中起重要作用，细胞凋亡是其机制之一。瞬时受体电位通道 6 (TRPC6) 在足细胞中表达，介导高葡萄糖水平诱导的足细胞损伤。他克莫司是一种新型免疫抑制剂，据报道在足细胞保护中起重要作用。本研究的目的是研究他克莫司在 2 型糖尿病 (T2DM) 大鼠模型和永生化小鼠足细胞 (MPC5) 中保护足细胞的潜在机制。透射电子显微镜用于评估肾损伤形态。用 FK506 治疗后，我们测量了 24 小时尿白蛋白肌酐比值和肌酐清除率以及主要生化参数，如葡萄糖、胰岛素、血清肌酐、尿素氮、总胆固醇、甘油三酯、丙氨酸转氨酶和天冬氨酸转氨酶。肾素和 TRPC6 蛋白表达和足细胞凋亡率分别使用免疫组织化学染色、TUNEL 测定和流式细胞术测量体内和体外。蛋白质印迹用于测量 cleaved-caspase-3 和 bax/bcl-2 的表达。暴露于高葡萄糖 (HG) 下，DM 大鼠表现出生化条件破坏和足细胞结构受损。在足细胞中发现 nephrin 表达降低，TRPC6、cleaved-caspase-3 和 bax/bcl-2 比率表达增加，以及更高的凋亡百分比，而他克莫司干预抵消了 HG 对足细胞的影响。我们的研究结果表明，他克莫司在 2 型糖尿病肾病进展过程中保护足细胞，可能通过下调 TRPC6 的表达来改善足细胞凋亡。