白细胞介素-1β激活HMGCoA还原酶促进HepG2细胞脂质积聚

IL-1β activates HMGCoAR and contributes to lipid accumulation in HepG2 cells

目的:探讨白细胞介素-1β(interleukin-1β,IL-1β)对HepG2细胞羟甲基戊二酸单酰辅酶A(3-hydroxy-3-methyl-glutaryl-coenzyme A,HMGCo A)还原酶及脂质积聚的影响。方法:200μg/m L低密度脂蛋白(low density lipoprotein,LDL)负荷下的HepG2细胞分别给予0 ng/m L(对照组)、20 ng/m L(炎症组)IL-1β处理24 h。荧光定量PCR(RT-PCR)、Western blot分别测定HMGCo A还原酶mRNA及蛋白表达水平;薄层层析法检测HMGCo A还原酶活性;同位素标记法评估胆固醇合成情况;油红O染色及酶法定量检测细胞内脂质。结果:IL-1β处理下,HepG2细胞HMGCo A还原酶mRNA表达水平为对照组的(1.54±0.04)倍(t=5.619,P=0.001)、蛋白表达水平为对照组的(1.92±0.12)倍(t=7.745,P=0.002),且HMGCo A还原酶的酶活性为对照组的(1.73±0.25)倍(t=2.476,P=0.048)。IL-1β处理使HepG2细胞的胆固醇合成增多为对照组的(1.32±0.11)倍(t=2.316,P=0.036)。IL-1β处理的HepG2细胞内红染的脂滴显著多于对照组,且IL-1β处理组细胞内总胆固醇含量(22.43±1.62)为对照组(14.90±1.11)的1.51倍(t=3.845,P=0.018),胆固醇酯的含量(3.84±0.20)为对照组(1.41±0.05)的2.72倍(t=11.730,P=0.000)。结论:IL-1β可以上调HepG2细胞HMGCo A还原酶的mRNA和蛋白表达水平,并增强其酶活性,促进HepG2细胞内胆固醇合成和脂质积聚。

Objective ： To investigate the effects of interleukin - 1β （ IL - 1β ） on 3 -hydroxy - 3 -methyl-glutaryl-coenzyme. A reductase （HMGCoAR） and lipid accumulation in HepG2 cells. Methods：Low density lipoprotein 200 μg/mL loaded HepG2 cells were treated with 0 ng/mL （control） or 20 ng/mL IL-1β for 24 hours. The mRNA and protein levels of HMGCoAR were measured by real-time PCR （RT-PCR） and Western blot respectively. HMGCoAR activity was evaluated by thin layer chromatography. Cholesterol synthesis was measured by isotopic labeling method. Intracellular lipids were visualized by oil red O staining and quantitatively analyzed by enzymatic method. Results ： IL-1β increased the mRNA levels of HMGCoAR to （1.54 ± 0.04） folds （t=5.619,P=0.001） and protein levels to （ 1.92 ± 0.12） folds （t =7.745, P=0.002）, as well＇ as its enzymatic activities to （1.73 ± 0.25） folds （t =2.476,P=0.048） in HepG2 cells. IL-1β also increased cellular cholesterol synthesis to （1.32± 0.11 ） folds（t=2.316,P=0.036）. Markedly red-dyed lipid droplets were observed in IL-1β-treated HepG2 cells. In IL-l[3-treated HepG2 cells,intracellular total cholesterol（22.43 ± 1.62） was increased to 1.51 folds comparing with that of control group（14.90 ± 1.11 ） （t=3.845 ,P=-0.018）, and cholesterol ester（3.84 ± 0.20） was increased to 2.72 folds comparing with that of control group （1.41 ± 0.05）（t=11.730, P=0.000）. Conclusion：IL-1β upregulates HMG- CoAR mRNA and protein levels,as well as its enzymatic activities, contributing to enhanced de novo cholesterol synthesis and lipid accumulation in HepG2 cells.