OBJECTIVETo understand the role of mitochondria associated signaling pathway in the apoptosis of human vascular endothelial cell induced by homocysteine (Hcy).

METHODSThe mRNA and protein expression levels of the up-stream signaling molecules of caspase 3, Bcl 2, caspase 9, and cytosolic cytochrome-c, were investigated. The in vitro cultured human umbilical vein endothelial cells with homocysteine at different concentrations were incubated for 24 h. The expressions of Bcl 2 and caspase 9 at mRNA and protein levels were analyzed by reverse transcription-polymerase chain reaction(RT-PCR) and Western blot. Cytochrome-c in cytoplasm was also detected by Western blot.

RESULTSThe expression levels of three signaling molecules were all down-regulated by homocysteine at both mRNA and protein levels in a dose-dependent manner.

CONCLUSIONHomocysteine could affect the formation of apoptosome through repressing the expression of Bcl 2 gene and release of cytochrome-c from mitochondria. Decreasing of apoptosome could disturb the activation of caspase 9. The results also indicate that the mitochondria pathway is not the major signaling pathway involved in Hcy-induced apoptosis.