转录因子NFI-C通过miR-200家族调控细胞自噬在神经管畸形发生中的作用与机制

We first reported that miR-200b can induce apoptosis leading to NTDs (Neural tube defects) through its target gene CITED2. Our preliminary studies found that a transcription factor, NFI-C, significantly increased in NTDs by using RNA-seq and it is predicted as a putative transcriptional regulator for miR-200b family. We also identified two novel target genes of miR-200 family, autophagy related gene Ambra1 and Atg5. Based on our findings, we hypothesize that NFI-C-suppressed Ambra1 and Atg5 through regulating miR-200s inhibit autophagy, impacting cell proliferation, differentiation and apoptosis, which is essential for neural tube closure. In the current study, we employ a retinoic acid-induced NTDs mouse model as well as NFI-C transgenic/knockout mouse model to investigate the relationship of NFI-C/miR-200s /Ambra1, Atg5, to demonstrate the function and mechanism of this axis in autophagy, proliferation, differentiation and apoptosis of NTDs. This project will provide scientific evidence for understanding for pathogenesis and new therapeutic treatments of NTDs.

申请人首次报道了miR-200b能通过CITED2促进细胞凋亡导致神经管畸形（NTDs）的产生。本课题预实验中，我们利用RNA-seq首次发现了一个转录因子NFI-C在NTDs小鼠中表达升高，而且预测显示NFI-C是miR-200家族的转录调节因子。进一步我们发现并证明了miR-200家族的两个新的靶基因，自噬相关基因Ambra1和Atg5。因此我们推测，NFI-C通过调节miR-200家族转录，抑制Ambra1和Atg5表达，减少细胞自噬，进而破坏细胞增殖、分化与凋亡平衡，最终导致NTDs。本研究中我们拟以NFI-C/miR-200家族/Ambra1、Atg5为主轴，用维甲酸灌胃制作的NTDs动物模型以及采用NFI-C转基因鼠和敲除鼠，研究此通路中各个因子间的调节关系，明确它们对细胞自噬、增殖、分化与凋亡的影响，为揭示NTDs发生发展机制和寻找新的临床治疗干预靶点提供重要的研究基础。

自噬受损和凋亡过度破坏细胞内稳态进而导致神经管畸形（neural tube defects, NTDs），一种由于在早期胚胎发育过程中神经管闭合失败引起的致命致残的出生缺陷。然而，NTDs的调控机制仍不清楚。本项目中，我们研究了转录因子核因子I-C (NFIC)在NTDs中维持细胞稳态的作用。在NTD小鼠模型中，异常升高的NFIC可以与miR-200b启动子相互作用，引起miR-200b转录激活，而miR-200b正如我们之前的报道所述，在NTDs的形成中发挥着关键作用。此外，miR-200b通过直接靶向自噬相关基因Ambra1 (Autophagy/Beclin1 regulator 1) 抑制自噬并触发细胞凋亡。值得注意的是，miR-200b抑制剂可以减轻NFIC对细胞自噬和凋亡的不良作用。总的来说，这些结果表明，NFIC-miR-200b-Ambra1轴整合了转录和表观基因组调控的miRNAs和自噬调节因子，在神经管关闭期间破坏细胞内稳态，并可能为NTDs的发病机制提供新的认识。