AMPK在病毒诱导的扩张性心肌病发病机制中的作用

Dilated cardiomyopathy (DCM) induced by virus, the further progress of viral myocarditis, is closely related with severe disturbance in myocardial function. And many severe cases could be developed to heart failure, sudden cardiac death, et al. It has been reported that DCM induced by virus has a close relation with energy metabolism of cardiac myocyte although its exact mechanism still missing. As one of the core signal-transduction molecules in energy metabolism of cardiomyocytes, amp-activated protein kinase (AMPK) has been found to modulate the pathological myocardial remodeling in our previous research work. While myocardial remodeling plays an important role in heart failure. Therefore, it's assumed that variable AMPK activity happens in the core pathogenesy of DCM induced by virus, which can be inhibited even avoided by regulated AMPK activity. To testify the assumption, the AMPKα2 knockout mouse will be used to produce the DCM mouse model induced by virus. Pathology dissect techniques, electron microscope, cytobiology and molecular biology techniques will be used to observe the effect of AMPK activity variation on DCM induced by virus from various scales, such as organ, tissue, cell and cytoskeleton proteins expression, et al. This subject will take a new view to illustrate the pathogenesis, and find a new drug-target of DCM induced by virus.

病毒诱导的扩张性心肌病是病毒性心肌炎的进一步发展，与重度心肌功能障碍密切相关，易致心衰、猝死等严重后果，确切发病机制尚不明了，但有报道认为与心肌细胞能量代谢关系非常密切。腺苷酸激活蛋白激酶（AMPK）是细胞内能量代谢的核心信号转导分子之一，我们前期研究发现过激活AMPK能调节病理状态下心肌重塑，而心肌重塑是心衰的重要发病机制，因此我们推测在病毒诱导的扩张性心肌病发病过程中存在AMPK活性变化，且是关键性发病环节之一，干预AMPK活性能够抑制该病的发生发展。为证实这一假说，我们将利用AMPK活性亚基α2基因敲除小鼠复制病毒诱导的扩张性心肌病小鼠模型，采用病理解剖、电镜、细胞生物学及分子生物学技术，从动物整体-心肌组织-细胞-相关骨架蛋白表达等多层面观察AMPK活性变化对病毒诱导的扩张性心肌病的影响。本课题将从新的视角阐明病毒诱导的扩张性心肌病发病机制，并为该病的防治提供新的药物作用靶点。

腺苷酸激活蛋白激酶（Amp-activated protein kinase, AMPK）则是细胞内信号转导通路的重要枢纽。尽管AMPK在心肌细胞能量代谢中的作用早已明确，但它与病毒性心肌炎及扩张性心肌病（Dilated cardiomyopathy, DCM）之间的确切关系仍不清楚。本课题通过体内实验观察了AMPK活性改变对病毒性心肌炎及扩张性心肌病小鼠心功能的影响，并进一步在体外实验中探讨其作用机制。结果显示，以腹腔注射法给予小鼠接种柯萨奇B3(Coxsackie virus, CVB3)病毒稀释液可形成DCM模型；应用AMPK激活剂Metformin能够有效缩小DCM模型鼠左室舒张末期内径(End diastolic dimension, EDD)、左室收缩末期内径(End systolic diameter, EDV)，提高心脏射血分数（Ejection fraction, EF），降低心肌纤维化面积。与野生型DCM模型鼠相比，AMPKα2基因敲除后DCM模型鼠EDD、EDV未见明显改变，但心脏EF值有较明显降低。在体外试验中，CVB3感染不能诱导心肌细胞发生病变效应，但能促进心肌成纤维细胞增殖及胶原分泌; AMPK激活剂5-Aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR)能够激活下游激酶p38-MAPK，并有效抑制CVB3对心肌成纤维增殖及胶原分泌的促进作用，这种抑制效应可被AMPK特异性抑制剂Compound C及拮抗；p38特异性抑制剂 SB203580能够有效阻断AICAR对心肌成纤维细胞胶原分泌的促进作用。这些研究结果提示AMPK-p38信号转导通路参与了CVB3诱导性DCM小鼠发生心肌纤维化及心功能降低的发病机制，调节AMPK活性可以有效影响CVB3诱导性病毒性心肌炎向DCM发展的过程。