OBJECTIVETo investigate the changes of expression and subcellular location of nuclear growth-induced protein-B(NGFI-B) in cardiomyocytes of stressed rats and its biological effect and to provide scientific evidences for exploring the mechanism underlying myocardium injury induced by stress.

METHODSThe cell model of stress-induced cardiomyocyte injury were established. Western blot method and confocal microscopy method were used to investigate the subcellular location of NGFI-B in cardiomyocytes under stress. The flow-cytometry was selected to detect the apoptotic rate in cardiomyocytes in vitro. Western blot method was used to determine the content of cytochrome C protein in mitochondria and cytoplasm respectively.

RESULTSStress induced the increase of NGFI-B content in the mitochondria of cardiomyocytes and the translocation of NGFI-B from the nucleus to the mitochondria. The translocation of NGFI-B promoted the release of cytochrome C from the mitochondria and the cardiomyocyte apoptosis. Treatment of stressed cardiomyocytes with leptomycin B, a non-specific blocker of nuclear export, resulted in nuclear retention of NGFI-B and abrogated its ability to induce the release of cytochrome C from the mitochondria.

CONCLUSIONStress could induce NGFI-B translocation from the nucleus to the mitochondria in cardiomyocytes, which activated the mitochondrial pathway of cell apoptosis.