The valproic acid (VPA)-induced animal model is one of the most widely utilized environmental risk factor models of autism. Autism spectrum disorder (ASD) remains an insurmountable challenge among neurodevelopmental disorders due to its heterogeneity, unresolved pathological pathways and lack of treatment. We previously reported that VPA-exposed rats and cultured rat primary neurons have increased Pax6 expression during post-midterm embryonic development which led to the sequential upregulation of glutamatergic neuronal markers. In this study, we provide experimental evidence that telomerase reverse transcriptase (TERT), a protein component of ribonucleoproteins complex of telomerase, is involved in the abnormal components caused by VPA in addition to Pax6 and its downstream signals. In embryonic rat brains and cultured rat primary neural progenitor cells (NPCs), VPA induced the increased expression of TERT as revealed by Western blot, RT-PCR, and immunostainings. The HDAC inhibitor property of VPA is responsible for the TERT upregulation. Chromatin immunoprecipitation revealed that VPA increased the histone acetylation but blocked the HDAC1 binding to both Pax6 and Tert genes. Interestingly, the VPA-induced TERT overexpression resulted to sequential upregulations of glutamatergic markers such as Ngn2 and NeuroD1, and inter-synaptic markers such as PSD-95, α-CaMKII, vGluT1 and synaptophysin. Transfection of Tert siRNA reversed the effects of VPA in cultured NPCs confirming the direct involvement of TERT in the expression of those markers. This study suggests the involvement of TERT in the VPA-induced autistic phenotypes and has important implications for the role of TERT as a modulator of balanced neuronal development and transmission in the brain.

中文翻译：

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丙戊酸在皮质发育过程中诱导端粒酶逆转录酶表达。

丙戊酸（VPA）诱导的动物模型是自闭症使用最广泛的环境危险因素模型之一。自闭症谱系障碍（ASD）由于其异质性，未解决的病理学途径和缺乏治疗，仍然是神经发育障碍中不可克服的挑战。我们以前曾报道过，在中期中期胚胎发育后，暴露于VPA的大鼠和培养的大鼠原代神经元Pax6表达增加，从而导致谷氨酸能神经元标志物的顺序上调。在这项研究中，我们提供实验证据，端粒酶逆转录酶（TERT），端粒酶核糖核蛋白复合物的蛋白质成分，除了Pax6及其下游信号外，还参与了由VPA引起的异常成分。如通过蛋白质印迹，RT-PCR和免疫染色所揭示的，在胚胎大鼠的大脑和培养的大鼠原代神经祖细胞（NPC）中，VPA诱导了TERT表达的增加。VPA的HDAC抑制剂特性负责TERT的上调。染色质的免疫沉淀表明，VPA增强了组蛋白的乙酰化作用，但阻止了HDAC1与两者的结合Pax6和Tert基因。有趣的是，VPA诱导的TERT过表达导致谷氨酸能标记物（如Ngn2和NeuroD1）和突触间标记物（如PSD-95，α-CaMKII，vGluT1和突触素）的顺序上调。Tert siRNA的转染逆转了培养的NPC中VPA的作用，证实了TERT直接参与这些标志物的表达。这项研究表明，TERT参与了VPA诱发的自闭症表型，并且对TERT作为大脑中平衡的神经元发育和传播调节剂的作用具有重要意义。