人参皂苷Rd对组蛋白H3乙酰化的调控机制研究

Regulatory mechanism of ginsenoside Rd on histone H3 acetylation

目的基于定量蛋白组学分析和分子生物学实验验证,阐明人参皂苷Rd调控组蛋白H3乙酰化水平的作用机制。方法利用氨基酸稳定同位素标记(SILAC)技术和液相色谱-质谱联用技术(LC-MS/MS)检测人参皂苷Rd作用下人胚肾HEK293T细胞蛋白质组的动态变化;通过对定量蛋白组学数据库分析监测组蛋白乙酰转移酶(HATs)和组蛋白去乙酰转移酶(HDACs)表达水平的变化,并通过Western blotting和实时荧光定量PCR(q RT-PCR)实验验证相关蛋白质表达和转录水平的变化;利用si RNA进行基因敲除实验以明确人参皂苷Rd对组蛋白H3K9和H3K18位点乙酰基修饰水平的调控作用。结果人参皂苷Rd处理HEK293T细胞后,组蛋白H3K9ac、H3K18ac表达水平降低,但催化修饰这2个位点的P300没有明显变化;同时人参皂苷Rd可上调HDAC2的转录和表达水平,si HDAC2处理HEK293T细胞后,逆转了人参皂苷Rd对H3K9ac、H3K18ac的下调作用。结论人参皂苷Rd通过上调HDAC2,下调组蛋白H3K9和H3K18位赖氨酸位点的乙酰化水平,从而影响下游基因的转录激活。

Objective Based on quantitative proteomics analysis and molecular biology experimental verification, the regulatory mechanism of ginsenoside Rd on histone H3 acetylation levels was elucidated. Methods The effects of ginsenoside Rd on the dynamic changes of proteome of HEK293 T cells were detected by.stable isotope labeling with amino acid（SILAC） technique and LC-MS/MS; Quantitative proteomics database analysis was used to monitor the changes in histone acetyltransferase HATs and histone deacetylase HDACs expression levels. Western blotting and q RT-PCR were used to verify the changes of related protein expression and transcriptional level. Gene knockdown experiments were performed using si RNAs to determine the role of ginsenoside Rd in regulating the level of acetyl modifications at histone H3 K9 and K18 sites. Results The histone H3 K9 ac, H3 K18 ac expression levels in HEK293 T cells decreased after ginsenoside Rd treatment, but the P300 catalytic modification of these two sites did not change significantly; At the same time, ginsenoside Rd up-regulated the transcription and expression of HDAC2, and si HDAC2 treatment reversed the down-regulation effects of ginsenoside Rd on H3 K9 ac and H3 K18 ac in HEK293 T cells. Conclusion Ginsenoside Rd down-regulates the acetylation level of lysine at histone H3 K9 and K18 sites by up-regulating HDAC2, thereby affecting transcriptional activation of downstream genes.