[Correlation between Mic60 haploid insufficiency and cardiac aging in mouse]

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.