中文摘要：

目的 探讨沉默信息调节因子1（silent mating type information regulation 2 homolog-1,SIRT1）对氧化型低密度脂蛋白（oxidized low density lipoprotein,ox-LDL）诱导的血管平滑肌细胞（vascular smooth muscle cell,VSMC）泡沫化的作用和相关的分子机制。方法 用组织贴块法体外培养原代VSMC,用80μg/mL ox-LDL刺激VSMC诱导泡沫细胞形成。检测SIRT1在ox-LDL刺激不同时间（24、48、72 h）的表达变化。SIRT1的活性调控分别应用SIRT1激动剂（SRT1720,SRT,1μmol/L）和抑制剂（nicotinamide,Nic,100μmol/L）进行干预。干预24 h后采用Western blot检测VSMC过氧化物酶体增殖物激活受体γ（peroxisome proliferator-activated receptorγ,PPARγ）、酰基辅酶A：胆固醇酰基转移酶1（A-cholesterol acyltransferase 1,ACAT1）的蛋白表达,干预48 h后采用油红O染色检测细胞内脂质沉积和泡沫细胞形成情况。应用PPARγ激动剂（Rosiglitazone,RSG,50μmol/L）和抑制剂（GW9662,10μmol/L）调控PPARγ的表达,Western blot检测VSMC中ACAT1的表达。结果 1ox-LDL诱导的VSMC泡沫细胞中,SIRT1蛋白表达在48 h降低约47%（P〈0.01）;油红O染色显示,SRT可以抑制VSMC泡沫细胞形成,而Nic可逆转SRT的抑制作用;2ox-LDL诱导的VSMC泡沫细胞中ACAT1的表达显著增加[（2.77±0.70）,P〈0.01],SIRT1激动剂SRT可显著抑制ACAT1的表达[（0.90±0.27）,P〈0.01],而SIRT1抑制剂Nic可阻断这一作用,升高ACAT1的表达[（2.25±0.37）,P〈0.05];3ox-LDL诱导的VSMC泡沫细胞中PPARγ的表达减少[（0.73±0.12）,P〈0.05],SIRT1激动剂SRT可上调VSMC中PPARγ的表达[（0.98±0.16）,P〈0.05],SIRT1抑制剂Nic抑制PPARγ的表达[（0.47±0.13）,P〈0.01];4PPARγ激动剂RSG可抑制ACAT1的表达[（0.73±0.09）,P〈0.01],而PPARγ抑制剂GW9662则上调ACAT1表达[（1.68±0.09）,P〈0.01]。结论 SIRT1通过上调VSMC中PPARγ表达而抑制ACAT1表达,从而抑制ox-LDL诱导的VSMC泡沫样变。

英文摘要：

Objective To determine the effect of silent information regulation 2 homolog-1 （ SIRT1 ） on foam cell formation in vascular smooth muscle cell （VSMC） after the inducement of oxidized low density lipoprotein （ox-LDL） and investigate the underlying mechanisms. Methods Primary VSMC were isolated from the aorta of male C57BL/6J mice and identified by immunofluorescence staining. The VSMC-derived foam cell formation was induced by the stimulation of 80 μg/mL ox-LDL for 24, 48 or 72 h. The expression profile of SIRT1 was measured in the process of foam cell formation. SIRT1 agonist SRT1720 （SRT, 1 μmol/L） and its antagonist nicotinamide （Nic, 100 μmol/L） were used as well. Western blotting was employed to measure the protein expression levels of peroxisome proliferator-activated receptor gamma （PPARγ） and acylcoenzyme a： A-cholesterol acyltransferase 1 （ACAT1）. Oil red O staining was used to detect intracellular lipid deposition and foam cell formation. PPARγ agonist rosiglitazone （ RSG, 50 μmol/L） and its inhibitor GW9662 （ 10 μmol/L） were used to manipulate the activity of PPARγ, and their effects on the expression of ACAT1 were detected by Western blotting. Results （1）The expression of SIRT1 in VSMC-derived foam cells was reduced approximately by 47% after 48 hours＇ ox-LDL incubation （P〈0.01）. Oil red O staining showed that SRT ＋ ox-LDL treatment inhibited the formation of VSMC-derived foam cells, while the stimulation of SIRT1 antagonist Nic reversed such effect. （2）The expression level of ACATI was enhanced in the VSMC- derived foam cells （2.77 ±0.70, P 〈0.01 ）, which could be counteracted by SRT （0.90 ±0.27, P 〈 0. 01 ）. However, Nic stimulation resulted in block in the inhibition and enhanced the expression of ACAT1 （2.25 ± 0.37, P 〈 0.05 ）. （~The expression of PPARγ was decreased in the VSMC after ox-LDL stimulation （0.73 ±0.09, P 〈 0.01 ）. SIRT1 agonist SRT significantly up-regulated the expression （0.98 ± 0.16,