Objective: 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) μm(2) vs.(358.8±48.7) μm(2), P<0.05] and interstitial fibrosis [ (38.24±7.58) ×10(3)μm(2) vs.(25.81±4.12)×10(3)μm(2,) 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.
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)μm(2)比(358.8±48.7)μm(2)，P<0.05]及心肌间质纤维化面积增多[(38.24±7.58)×10(3)μm(2)比(25.81±4.12)×10(3)μm(2)，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。.
Keywords: Age factors; Animal experimentation; Mitochondrial proteins; Myocytes, cardiac.