HIP-55 negatively regulates myocardial contractility at the single-cell level

Myocardial contractility is crucial for cardiac output and heart function. But the detailed mechanisms of regulation remain unclear. In the present study, we found that HIP-55, an actin binding protein, negatively regulates myocardial contractility at the single-cell level. HIP-55 was overexpressed and knocked down in cardiomyocytes with an adenovirus infection. The traction forces exerted by single cardiomyocyte were measured using cell traction force microscopy. The results showed that HIP-55 knockdown significantly increased the contractility of the cardiomyocytes and HIP-55 overexpression could markedly reverse this process. Furthermore, HIP-55 was obviously co-localized with F-actin in cardiomyocytes, suggesting that HIP-55 regulated cardiac contractile function through the interaction between HIP-55 and F-actin. This study reveals the regulatory mechanisms of myocardial contractility and provides a new target for preventing and treating cardiovascular disease.