Effect of oxidized LDL on the expression of connexins in cultured human umbilical-vein endothelial cells

The role of connexins in atherogenesis has attracted increasing attention in recent years; however, whether oxidized LDL (low density lipoprotein) is one of the pro-atherosclerotic factors that can influence the expression of endothelial connexins remains unclear. To investigate the effect of oxidized LDL on the gene expression of the gap junction proteins connexin37, connexin40 and connexin43 in cultured HUVEC (human umbilical-vein endothelial cells) in vitro, HUVEC were cultured and divided into groups before being stimulated with various concentrations of oxidized LDL for different times. mRNA expression of connexin37, connexin40 and connexin43 in each group were determined semi-quantitatively by RT-PCR (reverse transcription-PCR), while protein expression of the three connexins was investigated by immunocytochemical staining. Various concentrations of oxidized LDL down-regulated mRNA and protein expression of connexin37, and up-regulated the expression of connexin40 and connexin43. Time-dependent dynamic alterations of the mRNA expression levels of connexin37, connexin40 and connexin43 were also found in HUVEC stimulated by oxidized LDL. We conclude that oxidized LDL can change the expression of connexin genes in cultured HUVEC within a short period, and thus may be involved in the pro-atherosclerotic effect of oxidized LDL.