Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63, Gdansk 80-308, Poland; Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk 80-308, Poland.
Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63, Gdansk 80-308, Poland.
Cell Signal. 2023 May;105:110622. doi: 10.1016/j.cellsig.2023.110622. Epub 2023 Feb 6.
A decrease in intracellular levels of 3',5'-cyclic guanosine monophosphate (cGMP) has been implicated in the progression of diabetic nephropathy. Hyperglycemia significantly inhibits cGMP-dependent pathway activity in the kidney, leading to glomerular damage and proteinuria. The enhancement of activity of this pathway that is associated with an elevation of cGMP levels may be achieved by inhibition of the cGMP specific phosphodiesterase 5A (PDE5A) using selective inhibitors, such as tadalafil. Hyperglycemia decreased the insulin responsiveness of podocytes and impaired podocyte function. These effects were associated with lower protein amounts and activity of the protein deacetylase sirtuin 1 (SIRT1) and a decrease in the phosphorylation of adenosine monophosphate-dependent protein kinase (AMPK). We found that PDE5A protein levels increased in hyperglycemia, and PDE5A downregulation improved the insulin responsiveness of podocytes with reestablished SIRT1 expression and activity. PDE5A inhibitors potentiate nitric oxide (NO)/cGMP signaling, and NO modulates the activity and expression of SIRT1. Therefore, we investigated the effects of tadalafil on SIRT1 and AMPK in the context of improving the insulin sensitivity in podocytes and podocyte function in hyperglycemia. Our study revealed that tadalafil restored SIRT1 expression and activity and activated AMPK by increasing its phosphorylation. Tadalafil also restored stimulating effect of insulin on glucose transport in podocytes with high glucose-induced insulin resistance. Additionally, tadalafil improved the function of podocytes that were exposed to high glucose concentrations. Our results display novel mechanisms involved in the pathogenesis of glomerulopathies in diabetes, which may contribute to the development of more effective treatment strategies for diabetic nephropathy.
细胞内 3'，5'-环鸟苷单磷酸（cGMP）水平的降低与糖尿病肾病的进展有关。高血糖显著抑制肾脏中 cGMP 依赖性途径的活性，导致肾小球损伤和蛋白尿。通过抑制 cGMP 特异性磷酸二酯酶 5A（PDE5A）来增强该途径的活性，可使 cGMP 水平升高，使用选择性抑制剂如他达拉非可以达到这种效果。高血糖降低了足细胞对胰岛素的反应性并损害了足细胞的功能。这些作用与蛋白去乙酰化酶 SIRT1（沉默信息调节因子 2 相关酶 1）的蛋白含量和活性降低以及腺苷单磷酸依赖蛋白激酶（AMPK）的磷酸化减少有关。我们发现，PDE5A 蛋白水平在高血糖症中增加，而 PDE5A 的下调可通过重新建立 SIRT1 的表达和活性来改善足细胞对胰岛素的反应性。PDE5A 抑制剂增强了一氧化氮（NO）/cGMP 信号，而 NO 调节 SIRT1 的活性和表达。因此，我们研究了在改善高血糖症中足细胞的胰岛素敏感性和足细胞功能的情况下，他达拉非对 SIRT1 和 AMPK 的影响。我们的研究表明，他达拉非通过增加磷酸化来恢复 SIRT1 的表达和活性并激活 AMPK。他达拉非还恢复了高葡萄糖诱导的胰岛素抵抗下足细胞中胰岛素对葡萄糖转运的刺激作用。此外，他达拉非改善了暴露于高葡萄糖浓度下的足细胞的功能。我们的结果显示了涉及糖尿病肾小球病变发病机制的新机制，这可能有助于开发更有效的糖尿病肾病治疗策略。
