CD36在棕榈酸诱导的星形胶质细胞凋亡中的作用

Role of CD36 in palmitic acid-induced apoptosis of astrocytes

本文主要探讨分化抗原簇36(cluster of differentiation,CD36)在棕榈酸(palmitic acid,PA)诱导的星形胶质细胞凋亡中的作用。采用MTT法检测细胞活性、TUNEL法检测细胞凋亡,发现PA可使星形胶质细胞活性显著下降,凋亡显著增加。用流式细胞术检测星形胶质细胞对BODIPY FL C16的摄取,结果表明CD36在星形胶质细胞摄取PA过程中发挥关键作用。采用钙离子荧光染料和实时荧光记录系统检测细胞内钙离子浓度变化,发现PA进入细胞后可通过IP3受体(inositol trisphosphate receptor,IP3R)引起星形胶质细胞内钙释放和内质网钙衰竭。采用CM-H2DCFDA荧光染色方法检测细胞内氧自由基(reactive oxygen species,ROS)水平,发现PA可引起星形胶质细胞ROS水平显著增加。CD36抑制剂N-油酰基硫代琥珀酰亚胺(sulfo-N-succinimidyloleate,SSO)可以减少PA的摄取及其诱导的星形胶质细胞钙超载和ROS水平升高。IP3R抑制剂二苯基硼酸-2-氨基乙酯(2-aminoethyl diphenylborinate,APB)可以抑制PA引起的钙超载和ROS水平升高。SSO、APB和抗氧化剂N-乙酰半胱氨酸(N-acetyl-L-cysteine,NAC)对PA引起的星形胶质细胞活性下降均具有明显的保护作用。综上所述,CD36介导PA进入星形胶质细胞,进而引起钙超载和氧化应激,导致细胞凋亡。CD36可能成为保护星形胶质细胞的新靶点。

This study was designed to investigate the role of CD36 in palmitic acid （PA）-induced apoptosis of astrocytes and the potential mechanisms of the action. MTT assay was used to detect cell viability and TUNEL assay to detect cell apoptosis. It was found that PA significantly decreased astrocyte cell viability and increased cell apoptosis. The uptake of BODIPY FL C16 by astrocytes was measured by flow cytometry. The results showed that CD36 played a key role in the process of PA uptake by astrocytes. The changes of intracellular calcium concentration were detected by FLIPR real-time fluorescence recording system. It was found that IP3R mediated PA signal to induce intracellular calcium release and finally caused endoplasmic reticulum calcium depletion. The intracellular ROS level was detected with CM-H2DCFDA fluorescence staining. The ROS level was induced by PA in astrocytes. The effect was blocked by CD36 inhibitor SSO through inhibition of the uptake of PA. PA-induced calcium overload and ROS increase were prevented by IP3R inhibitor APB. SSO, APB and antioxidant NAC all had significant inhibitory effects on PA-induced astrocyte cell viability decrease. In conclusion, CD36 mediates the translocation of PA into astrocytes, which leads to calcium overload, oxidative stress and eventually cell apoptosis.