摘要目的 初步探索线粒体内膜蛋白Mic60与小鼠心脏衰老的关系.方法 将野生型及Mic60杂合缺失雄性小鼠分为青年组(4~6个月龄,6对)及老年组(18~20个月龄,9对),取心脏,制作石蜡、冷冻切片,提取组织蛋白.应用苏木精-伊红、Masson染色法鉴定小鼠心脏组织形态学变化;衰老相关β-半乳糖苷酶染色检测小鼠心肌组织中β-半乳糖苷酶活性;应用免疫印迹法检测野生型小鼠心肌组织中Mic60的表达及各组小鼠心肌组织中衰老相关蛋白p21的表达.结果 野生小鼠心肌组织中Mic60蛋白表达呈现年龄依赖性增高.Mic60杂合缺失导致老年小鼠左心室壁肥厚[(1.32±0.09)mm比(1.12±0.09)mm,P<0.05]、心肌细胞肥大[(474.9±27.6)μm2比(358.8±48.7)μm2,P<0.05]及心肌间质纤维化面积增多[(38.24±7.58)×103μm2比(25.81±4.12)×103μm2,P<0.05],但对年轻小鼠无显著影响.同时,Mic60杂合缺失导致老年小鼠心脏衰老相关β-半乳糖苷酶活性上调(2.26±0.24比0.25±0.05,P<0.01),对年轻小鼠无明显影响.另外,Mic60杂合缺失老年小鼠心肌组织中衰老相关蛋白p21表达显著增加(P<0.01).结论 通过对青年及老年组小鼠心脏衰老相关指标的检测,发现Mic60半量缺失可导致老年小鼠心肌肥厚、心肌间质纤维化及衰老相关β-半乳糖苷酶活性上调和衰老相关蛋白p21表达增加,提示线粒体内膜蛋白Mic60可能与小鼠心脏衰老有关.

abstractsObjective To investigate the role of Mic60 in cardiac aging.Methods Wild-type and Mic60+/-male mice at age of 4-6 months (young group, n=6) and 18-20 months (aged group, n=9) were used.H&E and Masson staining of frozen and paraffin sections were subjected to morphologic evaluation of the cardiac tissue samples.SA-β-Gal staining was utilized to detect the activity of senescence-associated β-galactosidase.Western blot was performed to detect the expression of Mic60 and p21 in cardiac tissues.Results Expression of Mic60 in mouse cardiac tissue increased in an age-dependent manner.Haploid insufficiency of Mic60 resulted in an increased left ventricular wall thickness [(1.32±0.09) mm vs.(1.12±0.09) mm, P<0.05], cardiomyocyte hypertrophy[(474.9±27.6) μm2 vs.(358.8±48.7) μm2,P<0.05] and interstitial fibrosis [(38.24±7.58) ×103μm2 vs.(25.81±4.12)×103μm2, P<0.05], increased activity of SA-β-Gal (2.26±0.24 vs.0.25±0.05, P<0.01) and higher expression of p21 (P<0.01) in aged mouse cardiac tissue, but not in young mice.Conclusion Haploid insufficiency of Mic60 leads to cardiac hypertrophy, interstitial fibrosis, increased activity of SA-β-Gal and higher expression of p21 in aged cardiac tissue in mice, suggesting that Mic60 may prevent cardiac aging.