VLDL受体的表达调控在泡沫细胞形成中的作用研究

ABSTRACT：The very low density lipoprotein receptor (VLDLR) is thought to participate in the pathogenesis of atherosclerosis induced by triglyceride-rich lipoprotein (TRL). The present study was undertaken to elucidate the effects of TRL on VLDLR expression、the signaling pathway for it and the role of VLDLR in cellular lipid accumulation and foam cell formation. The study on murine macrophages incubated with TRL showed that β-VLDL、VLDL increased VLDLR transcription, which was monitored at different levels including RT-PCR analysis of VLDLR mRNA and transcriptional regulation of VLDLR gene promoter-driven luciferase activity, but they had no or little effect on LDLR and LRP message. Using Western Blot Assay of phosphorylated ERK1/2 protein, we found that β-VLDL、VLDL stimulated ERK1/2 activity in a protein kinase C (PKC)-dependent manner. Studies using different protein kinases inhibitors or activators indicated that the effect of β-VLDL、VLDL-induced VLDLR transcription was extremely abolished by pretreating cells with PD98059, a inhibitor of ERK1/2 and GF 109203X, a inhibitor of PKC. Furthermore, the blocking of VLDLR expression by using antisense S-ODNs reduced partiallyβ-VLDL、VLDL-induced lipid accumulation. Finally, in comparison analysis of lipid contents and foam cell formation in VLDLR-trace expression ldl-A7 cells and VLDLR-overexpression ldl-A7-VR cells, we found thatβ-VLDL、VLDL increased substantially lipid contents and lead to foam cell formation in ldl-A7-VR cells , This effect did not occur in ldl-A7 cells. Taken together, our findings suggest that (a) β-VLDL、VLDL induced VLDLR mRNA expression via PKC/ERK1/2 signal pathway. (b) VLDLR plays a crucial role in TRL-induced foam cell formation. ..

在培养细胞中用反义核酸和单克隆抗体技术单一或不同组合阻断、封闭对VLDL具有交叉结合作用的LRP、LDL受体和VLDL受体，与VLDL进行不同浓度、不同时间温育后，测定三种受体在mRNA和蛋白水平表达变化和胞内脂质堆积的变化，以明确在泡沫细胞形成中VLDL受体表达上调的作用地位，并初步了解其调控，为TRL直接致AS提供新的实验依据和理论认识。