Inflammation, miRNA and autophagy in diabetes

项目摘要： 糖尿病的一个主要原因是骨骼肌对葡萄糖的摄取受损， 将额外的葡萄糖泵入血液导致高血糖症。临床研究显示， 糖尿病会导致心肌病，如果患者患有心脏病， 糖尿病与糖尿病相关的心功能障碍的机制之一是氧化 应激激活潜在基质金属蛋白酶9（MMP 9），进而诱导纤维化 和收缩功能障碍。然而，氧化应激如何激活的具体机制 导致收缩功能障碍的MMP 9尚未被研究。我们的初步 对HL 1心肌细胞的研究表明，抑制miR-133可诱导MMP 9及以上 miR-133的表达抑制MMP 9。荧光素酶报告基因检测显示，miR-133 靶向MMP 9。有趣的是，葡萄糖介导的MMP 9诱导被miR-133消除。在 在糖尿病秋田小鼠的心脏中，肌球蛋白增强因子2c（Mef 2c-miR-133的诱导剂）是 缓解后，miR-133下调，MMP 9稳定。这些结果让我们假设 氧化应激抑制Mef 2c，导致诱导MMP 9的miR-133减弱， 导致糖尿病中的收缩功能障碍。为了解决这个假设，我们制定了三个 具体目标： 目的#1：确定miR-133是否直接或间接抑制了 MMP9。 假设：MiR-133通过靶向MMP 9的3/ UTR直接抑制MMP 9。这也间接地抑制了 通过诱导miR-466和废除miR-705来抑制MMP 9。 目的#2：确定氧化应激是否抑制Mef 2c，从而引起Mef 2c的减弱。 miR-133与糖尿病 假设：氧化应激抑制Mef 2c，导致糖尿病中miR-133的衰减。 目的#3：确定miR-133或Mef 2c的过表达是否会抑制 MMP 9，进而改善骨骼肌中的葡萄糖摄取并改善收缩 糖尿病的功能障碍。 假设：miR-133和Mef 2c的过表达抑制了MMP 9，MMP 9增强了葡萄糖 通过骨骼肌摄取并减轻糖尿病中心肌细胞的收缩功能障碍。 我们的提议揭示了miR-133调控MMP 9的新机制。它还 提供了一个新的概念，即miRNA不仅通过直接靶向基因来抑制基因， 诱导/抑制间接影响靶基因的其他miRNA。在翻译水平上， 该提案将提供具体证据，证明miR-133过表达或 MMP 9可以改善糖尿病心肌病。

Project Summary: A major cause of diabetes is impairment of glucose uptake by skeletal muscle that causes pumping of extra glucose into blood leading to hyperglycemia. Clinical studies revealed that diabetes causes cardiomyopathy and the chances of heart failure increases if the patient has diabetes. One of the mechanisms of cardiac dysfunction associated with diabetes is oxidative stress that activates latent matrix metalloproteinase-9 (MMP9), which in turn induces fibrosis and contractile dysfunction. However, the specific mechanisms for how oxidative stress activates MMP9, which leads to contractile dysfunction, have not been investigated. Our preliminary studies on HL1 cardiomyocytes suggest that inhibition of miR-133 induces MMP9 and over expression of miR-133 inhibits MMP9. The luciferase reporter assay revealed that miR-133 targets MMP9. Interestingly, glucose mediated induction of MMP9 is abrogated by miR-133. In the heart of diabetic Akita mice, myosin enhancer factor 2c (Mef2c- an inducer of miR-133) is alleviated, miR-133 is down regulated and MMP9 is robust. These results lead us to hypothesize that oxidative stress inhibits Mef2c causing attenuation of miR-133 that induces MMP9 leading to contractile dysfunction in diabetes. To address the hypothesis, we formulated three specific aims: Aim#1: To determine whether the miR-133 directly or indirectly inhibits the activation of MMP9. Hypothesis: MiR-133 directly inhibits MMP9 by targeting its 3/ UTR. It also indirectly inhibits MMP9 by inducing miR-466 and abrogating miR-705. Aim# 2: To determine whether the oxidative stress inhibits Mef2c causing attenuation of miR-133 in diabetes. Hypothesis: The oxidative stress inhibits Mef2c that causes attenuation of miR-133 in diabetes. Aim # 3: To determine whether the over-expression of miR-133 or Mef2c will inhibit MMP9 that in turn improve glucose uptake in skeletal muscle and ameliorates contractile dysfunction in diabetes. Hypothesis: The over expression of miR-133 and Mef2c inhibits MMP9 that enhances glucose uptake by skeletal muscle and mitigates contractile dysfunction of cardiomyocytes in diabetes. Our proposal unravels a new mechanism of regulation of MMP9 by miR-133. It also provides a new concept that miRNA inhibits a gene not only by directly targeting it rather it also induces / inhibits other miRNAs that indirectly influences the target gene. At translational level, the proposal will provide concrete evidence that over expression of miR-133 or ablation of MMP9 can ameliorate diabetic cardiomyopathy.