miR-107调控系膜细胞和糖尿病肾病大鼠PARP-1表达的分子机制研究

Polyol pathway, advanced glycation end products (AGEs) pathway, protein kinase C pathway and hexose ammonia pathway are recognized as the fourth important injury mechanism. But, blocking either way did not achieve good results. Our previous NSFC study found that high glucose and AngII can promote the oxidative stress, and induce Poly ADP-ribose polymerase -1 (PARP-1) activation,following by regulating these four important damage pathways, triggering a series of complications of diabetes.Therefore, PARP-1 overexpression is regarded as a common pathogenesis of DN. However, the molecular mechanisms and signal pathways are not clear. Our previous study also found that miR-107 expression could be expressed in mesangial cells, and its expression was negatively correlated with PARP-1 expression. So, miR-107 may regulate the expression of PARP-1, and acts as the key factors involved in the pathogenesis of DN. In this study, we will up-regulate and down-regulate the miR-107 expression in mesangial cells in mice and kidney tissue of diabetic rats, and observed the regulating role of miR-107 in the expression of PARP-1 in DN diseases, to clarify its key role in the pathogenesis and prevention of DN.

多元醇途径、糖基化终产物、蛋白激酶C以及己糖氨途径是公认的糖尿病肾病（DN）四个重要损伤机制。但单一阻断其中任一途径并未取得理想疗效。我们上一个国家自然科学基金研究发现，高糖及AngII可促进氧化应激反应并诱导多聚ADP核糖聚合酶-1（PARP-1）表达和激活，从而激发上述四条损伤途径，引发一系列糖尿病并发症，因此PARP-1过表达被视为DN的共同发病机制。但调控PARP-1的分子机制和信号通路尚不明确。我们前期研究首次发现小鼠肾脏系膜细胞能表达miR-107，高糖可下调系膜细胞miR-107表达，其表达与PARP-1过表达呈负相关；miR-107可能是调控PARP-1表达，参与DN发病的关键因子。为此，在本课题中，我们将通过抑制和上调miR-107在小鼠系膜细胞中和糖尿病大鼠肾脏组织中的表达，探索miR-107调控DN PARP-1表达的分子机制，阐明其在DN发病机制及防治中的关键作用。

糖尿病肾病（DN）是糖尿病严重的并发症之一,肾小球系膜细胞损伤是糖尿病肾病进展、肾功能恶化、肾脏纤维化的关键机制。越来越多的证据表明microRNA表达异常在DN的发生发展中起到重要作用，我们首次证实小鼠肾脏组织、小鼠肾小球系膜细胞及人肾小球系膜细胞中存在miR-107的表达。本研究将围绕糖尿病肾小球系膜细胞病变机制展开，探讨miR-107调控PARP-1在糖尿病肾病肾小球系膜细胞纤维化中的关键作用。.本研究发现：.1.糖尿病小鼠肾脏组织miR-107表达下调，PARP-1表达升高，且两者呈负相关。.2.高糖诱导小鼠肾小球系膜细胞纤维化损伤加重，FN、COL IV、MMP-2、MMP-9表达升高；同时，miR-107表达下调，PARP-1表达升高，且两者呈负相关。等渗条件不引起上述指标改变。.3.高糖诱导人肾小球系膜细胞miR-107表达下调，PARP-1表达升高，且两者呈负相关。等渗条件不引起上述指标改变。.4.在人肾小球系膜细胞中过表达miR-107后，PARP-1表达降低，进一步提示了miR-107对PARP-1的调控作用；同时，FN表达降低，提示了miR-107/PARP-1在肾小球系膜细胞纤维化起到重要作用，miR-107具有潜在治疗价值。.5.双荧光素梅报告基因结果显示，miR-107负向调控PARP-1，证实两者的直接作用；.6.在AGEs刺激人原代肾小球系膜细胞中，PARP-1表达升高，STAT3磷酸化水平增加，纤维化指标COL1a1升高，提示了PARP-1/STAT3激活在促肾小球系膜细胞纤维化中的可能作用。.本研究通过体内体外实验发现：糖尿病肾病中，miR-107表达下调，引起PARP-1去抑制，进而STAT3磷酸化水平升高，加重肾小球系膜细胞纤维化水平，而外源性补充miR-107可以下调PARP-1蛋白表达、减轻肾小球系膜细胞损伤，展现了潜在的治疗价值。