兔主动脉平滑肌细胞低密度脂蛋白受体相关蛋白(LRP)的诱导表达调节

Regulation of Expression of Low Density Lipoprotein Receptor Related Protein(LRP) in Rabbit Aortic Smooth Muscle Cells

在兔主动脉平滑肌细胞 ( SMC)培养基中分别加入正常低密度脂蛋白 ( N- LDL)、氧化低密度脂蛋白 ( ox- LDL)、正常极低密度脂蛋白 ( N- VLDL)、氧化极低密度脂蛋白 ( ox- VLDL)和 β-极低密度脂蛋白 (β- VLDL )培养 2 4 h后 ,用定量 RT- PCR和配体结合实验检测平滑肌细胞 LRP的m RNA和蛋白质水平的表达 .结果表明 :五种脂蛋白均能在转录和翻译水平诱导兔主动脉平滑肌细胞的 LRP表达 ,尤以富含胆固醇的 N- LDL ,ox- LDL和β- VLDL的刺激作用更明显 .用胆固醇单独或与脂蛋白共同温育 SMC后 ,发现胆固醇本身可促进 SMC的 LRP蛋白水平的表达 ,脂蛋白与胆固醇的共同刺激作用更为显著 .结果提示 :上述五种脂蛋白对 SMC上 LRP的表达有上调作用 ,其机制可能主要是通过其中的胆固醇来实现的 .

The normal low density lipoprotein (N LDL),oxidized low density lipoprotein(ox LDL),β very low density lipoprotein(β VLDL),normal very low density lipoprotein(N VLDL) and oxidized very low density lipoprotein(ox VLDL) were incubated in rabbit aortic smooth muscle cells (SMCs) for 24 hours,respectively.The LRP expression at mRNA and protein levels in the cells was examined by quantitative RT PCR and ligand binding assay.The results indicated that all the lipoproteins could induce the expression of LRP in SMCs at transcription and translation levels.The effects of cholesterol rich lipoproteins (N LDL,ox LDL,β VLDL) on LRP expression were more obvious than the other two lipoproteins.When cholesterol with or without lipoproteins was incubated in SMCs,the expression of LRP in SMCs increased.Higher content of LRP was seen in cholesterol plus lipoprotein groups.These results suggested that the expression of LRP in SMCs could be up regulated by the five types of lipoproteins.The component of cholesterol in these lipoproteins may be responsible for the up regulation.