网膜素1通过PI3K/Akt途径上调ABCA1表达促进胆固醇流出

Omentin-1 upregulates ABCA1 expression via the PI3K/Akt pathway to promote cholesterol efflux

摘要:

目的]探讨网膜素1对巨噬细胞ATP结合盒转运体A1(ABCA1)表达及其介导的胆固醇流出的影响,并阐明其调控机制。 [方法]采用网膜素1孵育THP-1源性巨噬细胞24 h后,分别抑制和沉默磷脂酰肌醇3激酶(PI3K)和蛋白激酶B(Akt),采用Western blot检测ABCA1、肝X受体α(LXRα)等蛋白水平,通过高效液相色谱法测定细胞内总胆固醇(TC)、游离胆固醇(FC)及胆固醇酯(CE)含量,应用液体闪烁计数仪检测胆固醇外排,采用油红O染色观察细胞内脂滴情况。为深入探讨其作用机制,采用ABCA1特异性siRNA沉默技术,观察网膜素1对胆固醇流出的影响。 [结果]网膜素1呈剂量依赖性地增强巨噬细胞ABCA1的表达,促进胆固醇外排,降低细胞内TC、FC和CE的含量,减少脂质蓄积并抑制泡沫细胞形成。特异性沉默ABCA1表达后,网膜素1促进胆固醇外排的效应显著减弱,细胞内脂质蓄积增加,泡沫细胞形成明显增多。抑制或沉默PI3K与Akt后,LXRα和ABCA1的表达显著下调,网膜素1促胆固醇外排效应受到抑制,细胞内脂质蓄积增加,泡沫细胞形成增多。 [结论]网膜素1可通过PI3K/Akt途径上调巨噬细胞ABCA1的表达,增强胆固醇外排,进而减少脂质蓄积并抑制泡沫细胞形成。

Abstract:

Aim To investigate the effect of omentin-1 on the expression of ATP-binding cassette transporter A1 (ABCA1) in macrophages and its mediated cholesterol efflux, as well as to elucidate its regulatory mechanism. Methods After THP-1-derived macrophages incubated with omentin-1 for 24 h, phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) were inhibited and silenced, respectively. Western blot was used to detect protein levels of ABCA1 and liver X receptor α (LXRα), high performance liquid chromatography was adopted to detect total cholesterol (TC), free cholesterol (FC) and cholesterol ester (CE) content, a liquid scintillation counter was applied to determine cholesterol efflux, and intracellular lipid droplets were observed via oil red O staining. In order to explore its mechanism of action in depth, ABCA1-specific siRNA silencing technique was used to observe the effect of omentin-1 on cholesterol efflux. Results Omentin-1 increased the expression of ABCA1 in macrophages in a concentration-dependent manner, promoted cholesterol efflux, reduced the contents of TC, FC and CE in cells, reduced lipid accumulation and inhibited the formation of foam cells. After specifically silencing the expression of ABCA1, the effect of omentin-1 on cholesterol efflux was significantly weakened, the intracellular lipid accumulation was increased, and the formation of foam cells was significantly increased. After inhibiting or silencing PI3K and Akt, the expression of LXR α and ABCA1 was significantly downregulated, the cholesterol efflux effect of omentin-1 was inhibited, the intracellular lipid accumulation increased, and the formation of foam cells increased. Conclusion Omentin-1 can upregulate the expression of ABCA1 in macrophages through PI3K/Akt pathway, enhance cholesterol efflux, thereby reducing lipid accumulation and inhibiting the formation of foam cells.