LAUSR

Cardiomyocyte apoptosis induced by hypoxia and ischemia plays important roles in heart dysfunction after acute myocardial infarction (AMI). However, the mechanism of apoptosis induction remains unclear. A previous study reported that Y‐box protein 1 (YB1) is upregulated after myocardial hypoxia/reoxygenation or ischemia/reperfusion (H/R or I/R, respectively) injury; however, whether YB1 is associated with H/R‐induced cardiomyocyte apoptosis is completely unknown. In the present study, we investigated the roles of YB1 in H/R‐induced cardiomyocyte apoptosis and the possible underlying molecular mechanisms. In vitro, H/R treatment upregulated the YB1 expression in H9C2 cells, whereas YB1 knockdown inhibited H/R‐induced cardiomyocyte apoptosis and induced H9C2 cell proliferation via Src homology region 2 domain‐containing phosphatase 1 (SHP‐1)‐mediated activation of signal transducer and activator of transcription 3 (STAT3). In vivo, YB1 knockdown ameliorated AMI, reducing infarct size, cardiomyocyte apoptosis, and oxidative stress, via SHP‐1‐mediated inactivation of STAT3. Additionally, YB1 knockdown inhibited H/R‐ or I/R‐induced oxidative stress in vitro and in vivo. H/R and I/R increase YB1 expression, and YB1 knockdown ameliorates AMI injury via SHP‐1‐dependent STAT3 inactivation.