表观遗传因子在自闭症模型大鼠海马内的异常表达(英文)

Abnormal expression of epigenetic factors in the hippocampus of prenatal valproic acid exposure autistic rat model

目的:研究两个关键表观遗传修饰因子DNA甲基转移酶3b(DNMT3b)及甲基化CpG结合蛋白2(MeCP2)在VPA自闭症大鼠模型海马脑区的表达变化。方法:依孕期服用丙戊酸(valproic acid,VPA)会增加子代罹患自闭症易感性的机理,在大鼠孕12.5 d时,腹腔注射VPA以制作子代鼠自闭症模型。运用实时定量PCR检测子代鼠海马脑区DNMT3b及MeCP2的mRNA表达,并运用免疫荧光及免疫印迹技术检测DNMT3b及MeCP2蛋白的定位及定量表达变化。结果:与对照组比较,自闭症模型大鼠海马脑区DNMT3b基因的mRNA表达显著下降(P<0.01),而MeCP2基因的mRNA表达未见显著变化(P>0.05)。DNMT3b免疫阳性神经元数量及DN-MT3b蛋白水平均较对照组显著下降(P<0.001),而MeCP2免疫阳性神经元数量及DNMT3b蛋白水平未见异常变化。结论:大鼠孕期接触VPA引起子代鼠脑内某些表观遗传因子的异常表达,可能继而带来脑内基因表达谱异常,从而导致子代对自闭症易感。

Objective： The aim of this study was to investigate the changes of expression of two epigenetic factors, DNA methyltransferase 3b （DNMT3b） and methyl-CpG-binding protein 2 （ MeCP2）, which take the key position for epigenetic modification, in the hippocampus of an autistic rat model. Methods： The phenomenon that maternal administration of valproic acid （valproate, YPA） would remarkably increase susceptibility in the offspring to autism spectrum disorders （ASDs） leads to the production of autistic animal model. The rats were exposed in early pregnancy to VPA to produce au- tistic model in the offspring. Real-time PCR was used to examine the mRNA expression of DNMT3b and MeCP2; Immuofluorescence and Western blot were employed to detect the protein level of them in the hippoeampus of the autistic model or the control rats. Results： We found that the mRNA expression of DNMT3b, but not of MeCP2 was decreased in the hippocampus of autistic model, in comparison with the control rats （P 〈0.01 and P 〉0.05, respectively）. We also observed that the number of DNMT3b-immunoreactive neurons, as well as the protein level of DNMT3b was significantly decreased in the hippocampus of autistic model, in comparison with the control rats （P 〈 0. 001 ）. However, both the number of MeCP2-immunoreactive neurons and the protein level of MeCP2 didn＇t show abnormal change in autistic model. Conclusion： Some epigenetic factors such as DNMT3b is abnormally expressed in the brain regions of rats prenatally ex- posed to VPA, which may further bring about wide abnormal gene expression spectrum, thus facilitating susceptibility to ASDs.