髓样分化蛋白2（MD2）通过调控AMPK介导肥胖性心肌病的作用及机制研究

Metabolic disorders and excessive chronic inflammatory response are important pathological mechanisms of obesity cardiomyopathy. Studies have shown that high-fat can activate Toll-like receptor 4 (TLR4)/NF-κB inflammatory signaling pathway, accompanied by inhibition of AMPK activity. However, the molecular mechanism of interaction between inflammatory pathway and AMPK remains unclear. MD2 is an accessory protein to activate TLR4/NF-κB by pathogenic ligand. Our previous work found that MD2-/- knockout mice significantly alleviates obesity-induced myocardial injury compared with the wide-type mice, accompanied by activation of myocardial AMPK. Therefore, we hypothesized that MD2 mediates obesity-induced myocardial injury via regulating AMPK; AMPK is a target for the treatment of obesity cardiomyopathy. In this project, we intend to research the upstream and downstream molecular mechanisms of AMPK activity regulated by MD2 in vitro; and employ MD2-/- knockout mice, and adeno-associated virus-based tissue specific technology to over-expresses AMPK in vivo to confirm the role of MD2 via regulation of AMPK in obesity cardiomyopathy. The project will explain the molecular mechanism of the change of AMPK activity under the high-fat condition, and provide a novel theoretical basis for the prevention and treatment of obesity cardiomyopathy.

代谢紊乱和慢性过度炎症反应是肥胖性心肌病的重要病理机制。研究表明高脂可激活Toll样受体4（TLR4）/NF-κB炎症信号通路并伴随AMPK活性的抑制，然而炎症通路与AMPK交互作用的分子机理仍不清晰。MD2是递呈病原配体激活TLR4/NF-κB的辅助蛋白。我们前期工作发现：肥胖诱导的MD2-/-基因敲除小鼠的心肌损伤较野生型小鼠显著减轻，并伴随着AMPK的激活。因此我们假设：MD2通过调控AMPK介导肥胖诱导的心肌损伤；AMPK可作为肥胖性心肌病的治疗靶点。本项目中我们拟在细胞水平探索高脂条件下MD2调控AMPK活性的上下游分子机制；在动物水平利用MD2-/-基因敲除小鼠，以及利用腺相关病毒心肌特异性过表达AMPK，确证MD2通过调控AMPK介导肥胖性心肌病的作用。本项目将阐明高脂条件下AMPK活性改变的分子机制，为防治肥胖性心肌病提供新的理论依据。

肥胖性心肌病的病理发生机制仍不完全明确，研究其病理发生机制，确证药物防治的新靶点，寻求有效的治疗策略具有重要的科学意义和临床应用价值。在动物肥胖模型中，AMPK活性被显著抑制，伴随下游mTOR信号通路的激活，通过激活SREBP-1促进脂质合成，引起脂质过量堆积从而产生心脏脂毒性。同时，髓样分化蛋白2（MD2）介导的慢性炎症反应是肥胖性心肌病的重要病理过程。前期研究发现MD2特异性敲除明显缓解肥胖诱导的心肌损伤并伴随AMPK的激活。因此我们提出1）MD2通过调控AMPK活性介导肥胖性心肌病的发生与发展；2）AMPK可作为肥胖性心肌病的治疗靶点。.研究内容包括在细胞水平确认PA抑制AMPK活性的上游机制以及下游效应，以及MD2特异性抑制剂L6H9的对PA诱导心肌细胞损伤的保护作用；L6H9对高脂诱导肥胖小鼠心肌的保护作用：构建肥胖小鼠模型；L6H9对高脂饲料诱导的肥胖小鼠心功能、CK-MB、心肌组织纤维化和炎症因子水平的影响；利用MD2基因敲除小鼠，进一步验证MD2调控AMPK的作用：检测心功能、心肌组织纤维化、CK-MB、LDH等心肌损伤的指标，以及相关拓展研究揭示MD2对AMPK及下游靶点的调控作用。.研究结果明确了高脂条件下MD2通过AMPK调控下游脂质代谢；MD2通过调控AMPK活性介导肥胖性心肌病的发生与发展；MD2小分子抑制剂L6H9对肥胖性心肌病的药理作用。同时研究结果为研究肥胖性心肌病的病理发生机制、药物防治靶点以及有效的治疗策略提供新的思路和实验依据。