二十碳五烯酸改变JurkatT细胞膜脂肪微区域脂肪环境的研究

目的:研究二十碳五烯酸(EPA)处理后T细胞膜脂肪微区域中脂肪酸组成改变及其对磷脂分子中脂肪酰基取代基团的作用。方法:用不连续蔗糖密度梯度超速离心法分离T细胞膜脂肪微区域,然后用气相色谱分析细胞膜亚区域中脂肪酸组成,高效液相质谱联用测定膜脂肪微区域磷脂分子脂肪酸酰基取代基团的构成。结果:EPA处理使T细胞脂肪微区域中多不饱和脂肪酸(PUFAs),n-3PUFAs和n-3PUFAs/n-6PUFAs的比值升高;磷脂分子中除了鞘磷脂以外,其他的磷脂分子如磷脂酰胆碱、磷脂酰乙醇胺、磷脂酰丝氨酸、磷脂酰肌醇分子中一些脂肪酰取代基团有显著改变。结论:EPA处理明显改变T细胞膜脂肪微区域和可溶膜组分中脂肪酸的组成,改变磷脂分子脂肪酰基取代基团的构成,从而改变细胞膜脂肪微区域的脂肪环境。

POLYUNSATURATED FATTY ACIDS (20: 5 n-3) CHANGES OF LIPID COMPOSITION IN JURKAT T CELL MEMBRANE SUBDOMAINS

Objective: To investigate the effects of eicosapentaenoic acid (EPA, 20:5 n-3) supplementation on modulating lipid composition and fatty acyl substitution in their cytoplasmic and exoplasmic lipid leaflet in membrane subdomains. Method: Lipid rafts were isolated using discontinuous sucrose density gradient ultracentrifugation, and then fatty acids composition was determined by gas chromatography. Moreover, fatty acyl chains of several important phospholipids were analyzed by QTRAP LC/MS/MS system. Results: EPA treatment could alter lipid composition and resulted in a considerable increase of unsaturated fatty acyl chains in cell membrane from EPA-treated T cells compared with control cells. Effective incorporation of EPA in rafts was not only in the exoplasmic but also in the cytoplasmic membrane lipid leaflet. Conclusion: EPA treatment can alter the lipid environment in rafts and thereby disrupts raft structures. The results proposed a possible mechanism for explaining the immunosupressive function of PUFAs in clinic.