长链非编码RNA Meg3介导足细胞线粒体功能障碍在糖尿病肾脏病中的作用及机制的研究

The role of long non-coding RNA in the regulation of podocyte mitochondria function remains unclear. Some important results were found in our previous studies: long non-coding RNA Meg3 expression was increased in podocytes isolated from diabetic db / db mice and human podocytes cultured with high glucose, what’s more, phosphorylation of p53 in mitochondria were also increased in cultured human podocytes with high glucose. Down-regulation of Meg3 by SiRNA can attenuate mitochondrial dysfunction, lower phosphorylation of p53 expression induced by high glucose in podocytes. Some studies showed p53 played a role in the regulation on mitochondrial function. Accordingly, we hypothesize: high glucose induced Meg3 expression, increased phosphorylation of p53, migrated to mitochondria, induced mitochondrial dysfunction, caused podocyte injury, finally lead to onset and progression of diabetic kidney disease. To this end, we set up Meg3 knockout type 1 and type 2 diabetic mice, and culture human podocytes in vitro. We want to clarify the role of Meg3 regulation on podocyte mitochondrial function in diabetic kidney disease and the role of p53 involved with them by measuring parameters of podocyte injury and mitochondrial function in these vivo and vitro studies. This project will help to clarify the new mechanism of podocyte injury and form a potential therapeutic target in diabetic kidney disease.

长链非编码RNA对足细胞线粒体功能的调控作用尚未明确。我们前期研究发现：糖尿病db/db小鼠足细胞及高糖培养的人足细胞中均发现长链非编码RNA Meg3表达增加, 同时高糖可增加人足细胞p53磷酸化；下调Meg3表达可减轻高糖诱导的足细胞线粒体功能障碍，降低p53磷酸化。有研究提示p53参与调控线粒体功能。据此，我们假设：糖尿病肾脏病时，高糖作用足细胞，引起Meg3上调，导致p53磷酸化升高并向线粒体迁移，引起线粒体功能障碍，导致足细胞损伤，促进糖尿病肾脏病的发生和发展。为此，我们构建1型和2型Meg3基因敲除的糖尿病小鼠，体外培养人足细胞，检测足细胞和线粒体功能的改变，从体内和体外两方面明确Meg3在调控足细胞线粒体功能障碍中的机制及p53在其中的作用。该项目完成对进一步阐明糖尿病肾脏病足细胞损伤的新机制，寻找潜在的治疗靶点有重要意义。

线粒体的过度分裂在糖尿病肾脏病足细胞损伤中发挥重要作用，研究表明长链非编码RNA在糖尿病肾脏病的发生和发展中非常重要，然而，目前缺少长链非编码RNA在足细胞分裂与融合调控的研究。因此，我们通过体外培养人足细胞和建立Meg3 特异性敲低糖尿病小鼠，探讨Meg3 在糖尿病肾脏病足细胞线粒体过度分裂中作用及机制。我们发现糖尿病小鼠足细胞Meg3 表达增加，并且其表达量与足细胞数目密切相关；足细胞特异性敲低Meg3 可减轻其线粒体的过度分裂，改善肾脏病理及生理参数，同样的研究发现，在体外培养人足细胞敲低Meg3 ，可改善线粒体过度分裂，减少Drp1线粒体转位，减轻足细胞损伤；相反，当过度表达Meg3 时，足细胞出现显著的足细胞损伤、线粒体的过度分裂，Drp1及其磷酸化增加，使用Mdivi1 预处理，可显著降低线粒体的过度片段化，减轻足细胞损伤；但使用Mdivi1 预处理高糖作用的足细胞，同样可改善线粒体的过度片段化，减少Drp1的线粒体移位。因此，我们的结果表明，T糖尿病小鼠足细胞和高糖作用人足细胞中长链非编码RNA-Meg3显著升高，通过调控 Drp1及其线粒体移位参与线粒体过户分裂，促进足细胞损伤，该研究为糖尿病肾病足细胞的保护性治疗提供了潜在治疗靶点。