Chinese Medical Journal (Jan 2018)

Cardiac Hypertrophy is Positively Regulated by MicroRNA-24 in Rats

  • Juan Gao,
  • Min Zhu,
  • Rui-Feng Liu,
  • Jian-Shu Zhang,
  • Ming Xu

DOI
https://doi.org/10.4103/0366-6999.232793
Journal volume & issue
Vol. 131, no. 11
pp. 1333 – 1341

Abstract

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Background: MicroRNA-24 (miR-24) plays an important role in heart failure by reducing the efficiency of myocardial excitation-contraction coupling. Prolonged cardiac hypertrophy may lead to heart failure, but little is known about the role of miR-24 in cardiac hypertrophy. This study aimed to preliminarily investigate the function of miR-24 and its mechanisms in cardiac hypertrophy. Methods: Twelve Sprague-Dawley rats with a body weight of 50 ± 5 g were recruited and randomly divided into two groups: a transverse aortic constriction (TAC) group and a sham surgery group. Hypertrophy index was measured and calculated by echocardiography and hematoxylin and eosin staining. TargetScans algorithm-based prediction was used to search for the targets of miR-24, which was subsequently confirmed by a real-time polymerase chain reaction and luciferase assay. Immunofluorescence labeling was used to measure the cell surface area, and 3H-leucine incorporation was used to detect the synthesis of total protein in neonatal rat cardiac myocytes (NRCMs) with the overexpression of miR-24. In addition, flow cytometry was performed to observe the alteration in the cell cycle. Statistical analysis was carried out with GraphPad Prism v5.0 and SPSS 19.0. A two-sided P < 0.05 was considered as the threshold for significance. Results: The expression of miR-24 was abnormally increased in TAC rat cardiac tissue (t = −2.938, P < 0.05). TargetScans algorithm-based prediction demonstrated that CDKN1B (p27, Kip1), a cell cycle regulator, was a putative target of miR-24, and was confirmed by luciferase assay. The expression of p27 was decreased in TAC rat cardiac tissue (t = 2.896, P < 0.05). The overexpression of miR-24 in NRCMs led to the decreased expression of p27 (t = 4.400, P < 0.01), and decreased G0/G1 arrest in cell cycle and cardiomyocyte hypertrophy. Conclusion: MiR-24 promotes cardiac hypertrophy partly by affecting the cell cycle through down-regulation of p27 expression.

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