CDK9通过调控肾脏炎症反应介导糖尿病肾病的作用和机制研究

Diabetic nephropathy (DN) is one of the most important diabetic complications. Hyperglycemia-induced inflammation was the main pathological process of DN. Cyclin-dependent kinase 9 (CDK9) was recognized as not only a novel therapeutic target in cancers, but also a mediator of inflammation and fibrosis in a few non-neoplastic diseases. However, there is no study reporting about CDK9 in DN. Our previous studied revealed that phosphorylation of CDK9 was activated in glomerular mesangial cell of diabetic mice, and LDC, an inhibitor of CDK9, could alleviate DN by reducing inflammation in kidney. Therefore, it is warranted to hypothesize that CDK9 plays a critical role in the development of DN. Base on the research of literature and pilot experiments, we further proposed the hypothesis that high glucose (HG) induces inflammation in kidney through "STAT3/CDK9-MAPKs-AP-1" signaling pathway. With a series of molecular biology methods, this project was aimed to confirm the protective effects of inhibition and silence of CDK9 on DN of type 1 and type 2 diabetes mellitus, and elucidate the molecular mechanism of HG activating CDK9 via STAT3, as well as CDK9 stimulating inflammatory response via the phosphorylation of MAPKs which activates transcription factor AP1. This project provides a new target for the prevention and treatment of DN.

糖尿病肾病（DN）是糖尿病的重要并发症之一，高血糖诱导的炎症反应是DN主要病理过程。细胞周期依赖性激酶9（CDK9）被认为是肿瘤治疗药物的新靶点，在少量非肿瘤疾病中也可介导炎症和纤维化过程。它在DN中的作用尚无报道。我们前期研究发现，糖尿病小鼠肾小球系膜细胞中CDK9被磷酸化激活，CDK9抑制剂LDC可以通过减轻肾脏炎症反应缓解DN。由此我们提出假设：CDK9在DN发生发展过程中起重要作用，靶向CDK9可能成为DN防治的新策略。进一步，我们通过文献调研和预实验，提出高糖（HG）通过“STAT3/CDK9-MAPKs-AP1”诱导肾细胞炎症反应的机制假设。本项目拟采用系列分子生物学方法，确证CDK9抑制或沉默对1型和2型糖尿病肾病的保护作用，深入阐明HG通过STAT3激活CDK9、以及CDK9通过磷酸化MAPKs激活转录因子AP1从而上调炎症反应的分子机制。项目将为DN的防治提供新的靶点。

糖尿病肾病（DN）是糖尿病的常见且严重的并发症之一，它是终末期肾脏疾病（ESRD）形成的主要原因。尽管严格的血糖控制和降压/降脂治疗可以减慢DN的进展，但这些干预措施仍不足以阻止其发展为ESRD。因此了解DN进展的机制并确定潜在的治疗靶点至关重要。.在这项研究中，我们发现CDK9在糖尿病小鼠的肾脏中被激活为磷酸化形式。通过糖尿病小鼠肾脏组织病理染色、Western blot、RT-qPCR等检测发现CDK9抑制剂LDC可以缓解糖尿病诱导的肾功能障碍，缓解糖尿病诱导的肾脏炎症反应。此外，在体外细胞实验中，我们进一步证实了通过药理学抑制（LDC）和基因沉默来降低肾小球系膜细胞SV40中CDK9表达后，HG诱导的促纤维化、促炎症作用减弱，同时MAPK-AP1通路激活减弱。综上所述，我们发现高血糖/HG可以激活CDK9的磷酸化，进而激活MAPK-AP1炎症信号通路，最终引起炎症反应，诱导肾功能损伤。