组蛋白乙酰化修饰调控NF-κB驱动的PNPLA3基因表达的机制初探

Preliminary study of the mechanism of histone acetylation modification in regulating NF-κB-driven PNPLA3 gene expression in liver

目的探讨禁食/再喂食后小鼠肝脏Patatin样磷脂酶域蛋白3(PNPLA3)基因启动子核因子-κB(NF-κB)结合区域组蛋白H3K9乙酰化(H3K9ac)水平以及相关去乙酰化酶(HDAC)和乙酰化转移酶(HAT)的变化特点。方法根据体质量将18只C57BL/6小鼠随机分为3组各6只,分别为自由饮食组、禁食组(夜间饥饿24 h)和再喂食组(饥饿24 h后再自由摄食高蔗糖含量饲料12 h),分别予自由饮食、禁食和禁食后再喂食干预,检测并比较各组肝脏PNPLA3、NF-κB、HDAC(SIRT1、SIRT6)和HAT(GCN5、Elp3)基因表达情况,用染色质免疫共沉淀-定量PCR检测H3K9ac富集水平,并分析H3K9ac与PNPLA3表达的相关性。结果 3组比较,C57BL/6小鼠肝脏PNPLA3、NF-κB基因表达在禁食时下调,再喂食后又上调(P均<0.001)。H3K9ac水平变化与PNPLA3变化趋势一致(P均<0.05),相关分析提示两者具有相关性(rs=0.958, P <0.001);禁食组SIRT1和SIRT6表达水平较自由饮食组高,再喂食组两者水平均下降(P均<0.05),与H3K9ac变化趋势相反;GCN5、Elp3表达变化与SIRT1及SIRT6类似(P均<0.05)。结论 SIRT1和SIRT6相关H3K9去乙酰化涉及饮食调节NF-κB驱动的PNPLA3的表达。

Objective To characterize the changes in the levels of H3K9acetylation( H3K9ac) around the Nuclear factor-κB( NF-κB) binding site of PNPLA3 gene promoter and the expression levels of related deacetylase( HDAC) and acetyltransferase( HAT) enzymes in the liver of C57BL/6 mice during the fasting/re-feeding transition. Methods According to the weight, 18C57BL/6 mice were randomly assigned into the ad libitum feeding group( n = 6), fasting group( n = 6, fasting for 24 h during night) and re-feeding group( n = 6, 24-h fasting followed by ad libitum re-feeding with high sucrose diet for 12 h). Mice were subjected to fasting/re-feeding interventions. The expression levels of PNPLA3, NF-κB, HDAC(SIRT1, SIRT6) and HAT( GCN5, Elp3) genes were detected and compared among three groups. The H3K9ac enrichment level was assayed by using ChIP-qPCR. Correlation analysis was performed to analyze the relationship between H3K9ac and PNPLA3 expression levels. Results The expression levels of PNPLA3 and NF-κB genes in C57BL/6 mouse liver were significantly down-regulated during fasting and then significantly up-regulated after re-feeding( all P < 0.001). The changes in the H3K9ac expression level were consistent with those in PNPLA3( all P < 0.05). Correlation analysis suggested a significant association between H3K9ac and PNPLA3 expression levels( rs = 0.958, P < 0.001). The expression levels of SIRT1 and SIRT6 in the fasting group were significantly higher compared with those in the ad libitum feeding group, which were significantly down-regulated in re-feeding groups( all P < 0.05), contrary to the changing trend of H3K9ac. The changes in the expression levels of GCN5 and Elp3 were similar with those of SIRT1 and SIRT6( all P < 0.05). Conclusions SIRT1 and SIRT6-associated H3K9 deacetylation may be involved in the dietary regulation of NF-κB-driven PNPLA3 expression.