与肝X受体相关的脂肪酸合酶转录调控区乙酰化组蛋白动态表达

Dynamic expression of acetylated histone in transcription regulation area of fatty acid synthase related to liver X receptor

目的利用肝X受体(liver X receptor,LXRs)激动剂T0901317,对脂肪酸合酶(fatty acid synthase,FAS)基因转录调控区的组蛋白乙酰化状态进行研究,探讨FAS基因转录表达中是否存在组蛋白乙酰化引起的染色质重塑事件。方法用实时荧光定量PCR方法测定FAS mRNA的转录表达时间谱。通过染色质免疫沉淀技术,结合实时荧光定量PCR测定脂肪酸合酶基因转录调控区4个位点上乙酰化组蛋白H3和乙酰化组蛋白H4的表达情况。结果①T0901317作用2 h开始FAS mRNA表达呈时间依赖性增高(1.09倍,P>0.05),16 h达到峰值(4.25倍,P<0.01),48 h时仍明显高于0 h的表达(2.59倍,P<0.01)。②T0901317作用30 min,组蛋白H3乙酰化水平显著高于0 h水平(P<0.05),1 h降至0 h水平以下(仅上游2 000 bp位点差异有统计学意义P<0.05),2 h又接近或高于0 h水平(仅LXRE位点增高有统计学意义P<0.05)。③T0901317作用30 min,组蛋白H4乙酰化水平均较0 h增高(P<0.05),而1 h和2 h,其水平均低于0 h(P<0.05)。结论在LXRs激动剂T0901317的作用下,FAS基因mRNA水平呈时间依赖性增高;而在FAS基因转录早期,FAS基因转录起始点上下游约2 500 bp位置范围均有组蛋白乙酰化引起的染色质重塑改变,但这种改变是随位置、时间和组蛋白的不同,呈动态变化的过程。

Objective To determine the expression of acetylated histone in transcription regulation area of fatty acid synthase （FAS） gene with liver X receptor （LXR） agonist T0901317 and whether acetylated histone induces ehromatin remodeling during expression of FAS gene transcription. Methods Transcription expression time spectrum of FAS mRNA was detected by real-time fluorescence quantitative PCR. H3 and H4 expression levels at 4 transcription regulation area sites of FAS gene were measured by chromatin immunoprecip- itation and real-time fluorescence quantitative PCR respectively. Results The expression level of FAS mRNA increased in a time-dependent manner in 2 h after T0901317 was used （ 1.09, P 〉 0.05 ） and reached its peak at 16 h （4.25, P 〈0. O1 ）, which was significantly higher at 48 h than at 0 h （P 〈0.01 ）. The expression level of acetylated H3 was significantly higher at 30 rain than at 0 h after TO901317 was used （P 〈 O. 05 ） , and was lower than that at 0 h with a difference at 2 000 bp （ P 〈 0.05 ） and close to or higher at 2 h than at 0 h with a difference at LXRE （ P 〈 0.05 ）. The expression level of acetylated H4 was also higher at 30 rain than at 0 h after T0901317 was used （ P 〈 0.05 ） and lower at 1 and 2 h than at 0 h （P 〈 0.05 ）. Conclusion The expression level of FAS mRNA is increased in a time-dependent manner when the 3＂0901317 is used. Acetylated histone at 2 500 bp upstream and downstream at the transcription start site during early FAS transcription induces chromatin remodeling with the site of transcription used, and the expression level of histone. regulation area, the time when the T0901317 is