Inflammation, miRNA and autophagy in diabetes

项目总结： 糖尿病的一个主要原因是骨骼肌对葡萄糖的摄取受损，从而导致 向血液中泵入额外的葡萄糖导致高血糖。临床研究显示， 糖尿病会导致心肌病，如果患者患有心力衰竭 糖尿病。糖尿病心脏功能不全的机制之一是氧化。 激活潜伏性基质金属蛋白酶-9(MMP9)的应激反应，进而导致纤维化 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MMP9尚未被研究。我们的预赛 对HL1心肌细胞的研究表明，抑制miR-133可诱导MMP9及以上 MiR-133的表达抑制MMP9的表达。荧光素酶报告实验显示miR-133 目标是MMP9。有趣的是，葡萄糖介导的MMP9诱导被miR-133取消。在……里面 糖尿病秋田小鼠的心脏肌球蛋白增强因子2c(MEF2C-miR-133的诱导剂)是 缓解后，miR-133下调，MMP9强健。这些结果引出了我们的假设 氧化应激抑制MEF2C，导致miR-133的减弱，从而诱导MMP9 导致糖尿病患者的收缩功能障碍。为了解决这一假设，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血管紧张素转换酶激活 MMP9。 假设：MIR-133通过靶向MMP9的3/UTR直接抑制MMP9。它还间接抑制了 MMP9通过诱导miR-466和取消miR-705。 目的#2：确定氧化应激是否抑制MEF2C引起的 糖尿病患者的MIR-133。 假设：氧化应激抑制MEF2C，后者导致糖尿病患者miR-133的减弱。 目的#3：确定miR-133或MEF2C的过表达是否会抑制 MMP9，反过来促进骨骼肌对葡萄糖的摄取，改善收缩 糖尿病中的功能障碍。 假设：miR-133和MEF2C的过表达抑制MMP9增强血糖 通过骨骼肌摄取和减轻糖尿病心肌细胞的收缩功能障碍。 我们的建议揭示了miR-133调控MMP9的新机制。它还 提出了一种新的概念，即miRNA不仅通过直接靶向抑制基因，而且还 诱导/抑制其他间接影响靶基因的miRNAs。在翻译层面上， 该提案将提供具体证据，证明miR-133的过度表达或消融 MMP9可改善糖尿病心肌病变。

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.