Effects of Panax notoginseng saponins on the expression of sortilin and cholesterol metabolism in macrophages
Objective To explore the role of Panax notoginseng saponins(PNS)in regulating the expression of sortilin and ATP-binding cassette transporter A1(ABCA1)in macrophages,and the effect of PNS on inhibiting formation of foam cells and the potential mechanism of PNS adjusting sortilin expression and cholesterol metabolism.Methods The macrophages were divided into five groups as follows:group A(only added with cell culture),group B(transfected with negative control lentivirus),group C(transfected with lentivirus-mediated sortilin overexpression),group D(transfected with lentivirus-mediated sortilin overexpression+60 μg·mL-1PNS),group E(transfected with lentivirus-mediated sortilin overexpression+10 μmol·L-1 mitogen-activated protein kinase kinase(MEK)inhibitor PD98059+60 μg·mL-1 PNS).The protein contents of sortilin,ABCA1,extracellular signal-regulated kinase(ERK)and phosphorylated-ERK(p-ERK)were evaluated with Western blot.All the cells in five groups were cultured with 50 μg·mL-1ox-LDL to form foam cells.The lipid in macrophages was investigated with red O assay.Results The relative expression levels of sortilin protein were 1.00±0.08,0.91±0.15,2.28±0.13,1.62±0.09 and 2.01±0.08;the relative expression levels of ABCA1 protein were 1.00±0.01,0.92±0.07,0.29±0.04,0.66±0.09 and 0.44±0.07;the ratios of p-ERK/ERK protein were 1.00±0.09,0.92±0.05,1.03±0.12,2.00±0.12 and 1.64±0.14;the contents of lipid in macrophages were(4.82±2.19)%,(6.70±0.88)%,(44.56±4.15)%,(27.66±3.25)%and(41.67±5.45)%.Except the ratios of p-ERK/ERK,the other parameters between group C and group A were statistically significant difference(all P<0.01).Meanwhile,there were also statistically significant difference between group D and group C as well as group D and group E(P<0.05,P<0.01).Conclusion PNS inhibits the lipid accumulation in macrophages through upregulating ABCA1 and downregulating sortilin,and ERK signaling pathway may be as one of important mechanisms influencing the expression of sortilin and ABCA1 mediated by PNS.