Apolipoprotein-J Prevents Hypoxia/reoxygenation Induced Injury In Neonatal Rat Ventricular Cells

Acute myocardial infarction(AMI) is a severe type of coronary heart disease, it is one of major cause of death and disability throughout the world nowadays. With the improvement of the medical science, such as intravenous thrombolysis?percutaneous coronary intervention and coronary artery bypass grafting to restore the blood follow of occlusive artery as soon as possible, thus to reduce the infarction area and improved clinical outcome. However, ischemia/refusion(I/R) injury is unavoidable and hard to overcome. So how to reduce I/R injury has gradually become the research hotspot.The pathogenetic mechanism of Myocardial I/R injury is complex, including intracellular calcium overload, mitochondria dysfunction, oxidative stress, endoplasmic reticulum stress, cell apoptosis and the activation of autophagy etc. Apoptosis is one of the important factors in the process of I/R induced injury, therefore, reducing the apoptosis of myocardial cells could alleviate the myocardial I/R injury.Apolipoprotein-J(ApoJ) is a multifunction glycoprotein widely present in tissues and body fluids. It has been implicated in such diverse progress. Apoptotic processes are responsible for increased ApoJ expression, and the function of ApoJ has been proposed to limit tissue injury. This study aimed to determin whether ApoJ overexpression provides cardio-protection against hypoxia/reoxygenation(H/R) induced injury and to exploe the mechanisms by which ApoJ exerts its protective effect.ApoJ expression was achieved by infection with recombinant adenovirus in NRVCs. Using three gas incubator establish H/R model, SOD mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride and e IF2?dephosphory inhibitor Salubrinal pretreatment. We then determined the effect of ApoJ in H/R-induced cell injury. The NRVCs were divided into four gourps: control adenovirus-infected cells ? H/R cells ?ApoJ-transduced cells ? ApoJ+H/R cells ? Mn(III)TBAP+H/R cell ?Salubrinal+H/R cells. The cell viability was measured by MTT assay; the leakages of LDH, the activity of SOD and caspase-3/7 activity were detected by Elisa kit. The protein expression levels of ApoJ ?Nox2/gp91phox?caspase-12?CHOP, and the phosphorylation level of eukaryotic initiation factor 2?(eIF2?)were determined by western blot.ApoJ expression after infection by recombinant adenovirus was significantly increased compared with control adenovirus-infected cells. In culture, NRVCs were damaged by exposure to H/R, cell viability and the activity of SOD were significantly decreased, the leakages of LDH and the activity of caspase-3/7 were increased in H/R group(P<0.05). The protein expression level of Nox2/gp91phox? caspase-12 ? CHOP and the phosphorylation level of eIF2? were increased. Nevertheless, ApoJ overexpression ?Mn(III)TBAP and Salubirnal decreased the leakages of LDH and the activity of caspase-3/7 compared with H/R group. ApoJ overexpressionincreased cell viability and the activity of SOD. Moreover, the protein expression level of Nox2/gp91phox?caspase-12 and CHOP were significantly decreased, while the phosphorylation level of eIF2? were markedly increased by overexpression of ApoJ(P<0.05).To summary, 1. ApoJ plays a role in reducing myocardium cell injury induced by H/R. 2. ApoJ serves as a cytoprotective protein in NRVCs against cytotoxicity of H/R by inhibiting the oxidative stress.3.The function of ApoJ to alleviate the endoplasmic reticulum stress may be via activated PERK/eIF2? signal transduction pathway.