We investigated the role of SYT1 in the development of TAC-induced cardiac hypertrophy in mice in vivo and Ang II-induced cardiomyocyte hypertrophy in H9C2 cells in vitro, and found that Syt1 KO or silencing exacerbated cardiac hypertrophy, dysfunction, fibrosis and cardiomyocyte apoptosis, strongly suggesting that SYT1 is a protective factor of cardiac hypertrophy. The gene discussed is AGT; the disease is cardiac hypertrophy.