The overexpression of CGRRF1 induces hypertrophy in cultured cardiomyocytes
【Background】Cardiomyocytes (CMs) are terminally differentiated cells that lose proliferative capacity immediately after birth; however, it remains to be fully elucidated how CMs exit from cell cycle and reach maturity. In this study, among the factors involved in cell cycle arrest, we focused on Cell Growth Regulator With Ring Finger Domain 1 (CGRRF 1).
【Objective】To explore the biological significance of CGRRF1 in CMs.
【Methods and Results】Real time RT-PCR analyses demonstrated that the expression of CGRRF1 mRNA was increased in murine adult hearts, compared with neonatal hearts.  Next, we examined the expression of CGRRF1 mRNA in adult and neonatal CMs and found that CGRRF1 expression was remarkably upregulated in adult CMs. Since the expression level of CGRRF1 increases in cells expressing p53, neonatal rat CMs were infected with adenoviral vector expressing p53. The overexpression of p53 enhanced expression of CGRRF1 mRNA. Finally, in order to investigate the biological function of CGRRF1, we constructed adenoviral vector expressing CGRRF1. Interestingly, CGRRF1 overexpression resulted in CM hypertrophy.
【Discussion】CGRRF1 was induced in CMs during growth. The overexpression of CGRRF1 enlarged CMs, suggesting that CGRRF1 may be related to CM maturation.

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