The Effect And Mechanism Of NgBR On Reverse Cholesterol Transport Of RAW264.7 Derived Foam Cells

Objective:By transfection of small interfering RNA(siRNA) to silence RAW264.7 derived foam cells’ neurite outgrowth inhibitor-B receptor(NgBR) expression, to study the effect and mechanism of NgBR on reverse cholesterol transport(RCT) of foam cells,to explore new methods to prevent atherosclerosis(AS) from RCT pathway,and to provide new ideas for clinical prevention and treatment of coronary heart disease. Methods:Using oxidized low density lipoprotein(ox-LDL) to induce the RAW264.7 cells to form foam cells, and using the oil red O staining to identify them.Then the foam cells were divided into 4 groups: blank control group(CON), siRNA negative control group(NC), NgBR-siRNA1 transfection group(siNgBR-1) and NgBR-siRNA2 transfection group(siNgBR-2).Whereafter used siRNA to silence NgBR expression in RAW264.7 cells, and the interference efficiency was identified by Real-time PCR and Western blot.Then applied Real-time PCR to detect mRNA content of liver X receptor alpha(LXR α), ATP binding cassette transporter A1(ABCA1), ATP binding transporter G1(ABCG1) in cells of each group,and corresponding protein content of each group cells were detected by Western blot,and the intracellular cholesterol efflux was determined by liquid scintillation counter. Results:ox-LDL induced foam cells formation successfully;Compared with other groups,NgBR mRNA and protein content were significantly decreased in siNgBR-1 and siNgBR-2 group(P<0.05); Compared with other groups,mRNA and protein expression of the genes related to RCT- ABCA1,LXR,ABCG1 were significantly inhibited in siNgBR-1 and siNgBR-2 group(P<0.05), and the cholesterol efflux was significantly reduced in siNgBR-1/2 group(P<0.05). Conclusion:NgBR can increase the expression of LXR α and its downstream genes as ABCA1 and ABCG1 which related to RCT regulation of macrophage derived foam cells and it can increase the intracellular cholesterol efflux,thereby weakening or avoiding the occurrence and development of atherosclerosis,and provide the theoretical basis for clinical prevention and treatment of coronary heart disease.