目的 探讨分子伴侣介导的自噬（chaperone-mediated autophagy, CMA）对未结合胆红素（unconjugated bilirubin, UCB）诱导的小鼠小胶质细胞BV2损伤的影响。 方法 BV2细胞实验分为两部分。（1）CMA激活实验分为：对照组（等体积二甲基亚砜处理）、QX77组（20 μmol/L QX77处理24 h）、UCB组（40 μmol/L UCB处理24 h）、UCB+QX77组（20 μmol/L QX77和40 μmol/L UCB共处理24 h）。（2）细胞转染实验分为：LAMP2A沉默对照组（等体积二甲基亚砜处理）、LAMP2A沉默对照+UCB组（40 μmol/L UCB处理24 h）、LAMP2A沉默组（等体积二甲基亚砜处理）、LAMP2A沉默+UCB组（40 μmol/L UCB处理24 h）。采用改良MTT法检测细胞存活率，蛋白免疫印迹法检测p65、核苷酸结合寡聚化结构域样受体蛋白3（nucleotide-binding oligomerization domain-like receptor protein 3, NLRP3）、半胱氨酸天冬氨酸蛋白水解酶-1（cysteinyl aspartate specific proteinase-1, caspase-1）蛋白表达水平，实时荧光定量聚合酶链反应法检测炎症因子白细胞介素（interleukin, IL）-1β、IL-6、肿瘤坏死因子-α（tumor necrosis factor-α, TNF-α）mRNA相对表达量，ELISA法检测细胞培养上清液中炎症因子IL-6和TNF-α水平，免疫荧光法检测细胞内p65、NLRP3与热休克同源蛋白70的荧光共定位。 结果 与UCB组相比，UCB+QX77组细胞存活率升高，炎症相关蛋白p65、NLRP3、caspase-1表达水平降低，炎症因子IL-1β、IL-6、TNF-α mRNA相对表达量降低以及IL-6、TNF-α水平降低（P<0.05）。与对照组相比，UCB组和UCB+QX77组热休克同源蛋白70与p65、NLRP3存在共定位。沉默LAMP2A基因后，与LAMP2A沉默对照+UCB组相比，LAMP2A沉默+UCB组炎症相关蛋白p65、NLRP3、caspase-1蛋白表达水平升高，炎症因子IL-1β、IL-6、TNF-α mRNA相对表达量升高以及IL-6、TNF-α水平升高（P<0.05）。 结论 CMA在UCB诱导的BV2细胞损伤中被抑制，激活CMA可能通过降低p65和NLRP3蛋白水平，抑制炎症反应，拮抗胆红素神经毒性。
Abstract
Objective To investigate the effect of chaperone-mediated autophagy (CMA) on the damage of mouse microglial BV2 cells induce by unconjugated bilirubin (UCB). Methods The BV2 cell experiments were divided into two parts. (1) For the CMA activation experiment: control group (treated with an equal volume of dimethyl sulfoxide), QX77 group (treated with 20 μmol/L QX77 for 24 hours), UCB group (treated with 40 μmol/L UCB for 24 hours), and UCB+QX77 group (treated with both 20 μmol/L QX77 and 40 μmol/L UCB for 24 hours). (2) For the cell transfection experiment: LAMP2A silencing control group (treated with an equal volume of dimethyl sulfoxide), LAMP2A silencing control+UCB group (treated with 40 μmol/L UCB for 24 hours), LAMP2A silencing group (treated with an equal volume of dimethyl sulfoxide), and LAMP2A silencing+UCB group (treated with 40 μmol/L UCB for 24 hours). The cell viability was assessed using the modified MTT method. The expression levels of p65, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), and cysteinyl aspartate specific proteinase-1 (caspase-1) were detected by Western blot. The relative mRNA expression levels of the inflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were determined by real-time quantitative polymerase chain reaction. Levels of IL-6 and TNF-α in the cell culture supernatant were measured using ELISA. The co-localization of heat shock cognate protein 70 with p65 and NLRP3 was detected by immunofluorescence. Results Compared to the UCB group, the cell viability in the UCB+QX77 group increased, and the expression levels of inflammation-related proteins p65, NLRP3, and caspase-1, as well as the mRNA relative expression levels of IL-1β, IL-6, and TNF-α and levels of IL-6 and TNF-α decreased (P<0.05). Compared to the control group, there was co-localization of heat shock cognate protein 70 with p65 and NLRP3 in both the UCB and UCB+QX77 groups. After silencing the LAMP2A gene, compared to the LAMP2A silencing control+UCB group, the LAMP2A silencing+UCB group showed increased expression levels of inflammation-related proteins p65, NLRP3, and caspase-1, as well as increased mRNA relative expression levels of IL-1β, IL-6, and TNF-α and levels of IL-6 and TNF-α (P<0.05). Conclusions CMA is inhibited in UCB-induced BV2 cell damage, and activating CMA may reduce p65 and NLRP3 protein levels, suppress inflammatory responses, and counteract bilirubin neurotoxicity.
关键词
胆红素 /
分子伴侣介导的自噬 /
神经毒性 /
小胶质细胞
Key words
Bilirubin /
Chaperone-mediated autophagy /
Neurotoxicity /
Microglia
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参考文献
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基金
国家自然科学基金项目（81971426）；重庆市技术创新与应用发展专项重点项目（CSTB2022TIAD-KPX0147）。
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