组蛋白去乙酰化酶SIRT1经Toll样受体4途径对巨噬细胞凋亡的调控

目的 观察组蛋白去乙酰化酶——人沉默调节蛋白(SIRT1)经组蛋白表观遗传学调控细胞凋亡的具体机制和途径,为动脉粥样硬化防治提出新思路。 方法 选用假手术组大鼠作为对照,观察颈动脉损伤组大鼠颈动脉组织凋亡、SIRT1、组蛋白3(H3)、H3赖氨酸9位点乙酰化(H3K9Ac)及炎症因子蛋白表达;选用不同条件干预的氧化低密度脂蛋白(oxLDL)暴露巨噬细胞为研究对象,采用细胞功能获得或缺失方法,观察巨噬细胞凋亡、SIRT1、H3、H3K9Ac及炎症因子蛋白表达。 结果 与假手术组大鼠和对照组巨噬细胞比较,颈动脉损伤组大鼠颈动脉组织和oxLDL暴露巨噬细胞SIRT1蛋白表达减少,H3K9Ac/H3比值增加,Toll样受体4(TLR4)、白介素1β(IL-1β)蛋白表达增加且伴有凋亡增加(P<0.01);与给予SP600125(JNK 通路拮抗剂)、IAXO-102(TLR4通路拮抗剂)、LY294002(PI3K 通路拮抗剂)干预的巨噬细胞比较,IAXO-102干预后,SIRT1减少现象被逆转(P<0.01);给予SIRT1兴奋剂后,巨噬细胞凋亡减轻伴有H3K9Ac/H3比值减少,TLR4、IL-1β蛋白表达减少(P<0.01);给予SIRT1抑制剂后,巨噬细胞凋亡加重伴有H3K9Ac/H3比值增加,TLR4、IL-1β蛋白表达增加(P<0.01)。 结论 组蛋白乙酰化表观遗传学参与细胞凋亡的调控,进而与动脉粥样硬化发生发展密切相关。组蛋白去乙酰化酶SIRT1减少,H3乙酰化增加,恶化细胞凋亡,促发动脉粥样硬化发生发展,这个过程必经TLR4途径实现。

Mechanism of histone deacetylase SIRT1 inhibiting macrophages apoptosis via TLR4 signaling pathway

Objective To observe the mechanism and specific inflammatory pathways of histone deacetylase SIRT1 involved in the regulation of atherosclerosis through histone epigenetics. Methods Rats with high-fat diet and carotid artery injury and oxidized low-density lipoprotein(oxLDL)exposed macrophages under different conditions were selected as the research subjects. Apoptosis, protein expression of SIRT1, histone H3(H3), histone H3 lysine 9-site acetylation(H3K9Ac)and inflammatory factors in rats and macrophages were observed by cells function acquisition or deletion experiments. Results Compared with the control rats and macrophages, rat models with carotid artery injury and oxLDL exposed macrophages had reduced protein expression of SIRT1, increased ratio of H3K9Ac/H3, increased apoptosis, and increased protein expressions of TLR4 and IL-1β(P<0.01). After treatment of SP600125(JNK pathway antagonist), IAXO-102(TLR4 pathway antagonist), LY294002(PI3K pathway antagonist), the phenomenon of SIRT1 reduction was reversed in IAXO-102 intervention macrophages(P<0.01); after treatment of SIRT1 stimulant, apoptosis was reduced accompanied by a decreasing in the ratio of H3K9Ac/H3 and protein expressions of TLR4 and IL-1β(P<0.01). The results were reversed after treatment of SIRT1 inhibitor(P<0.01). Conclusion Histone acetylation epigenetics is involved in the regulation of apoptosis, which is closely related to the occurrence and development of atherosclerosis. Apoptosis is worsened by a decrease in histone deacetylase SIRT1 and an increase in H3 acetylation, which promotes the development of atherosclerosis, and this process must be achieved through the TLR4 signaling pathway.