Immune challenge effects on RNA-editing in the human IPSC-derived neurons and microglia-like cells

通过流行病学研究和动物模型确定，母体免疫激活（MIA）是神经发育障碍的已知环境风险因素（Brown & Meyer, 2018）。导师实验室之前的工作表明，细胞因子暴露的影响也可以在人类诱导多能干细胞（iPSC）衍生的神经元中成功模拟，这些暴露于干扰素γ (IFNY)的细胞显示出持续的基因表达变化（Warre-Cornish等人，2020）。然而，目前尚不清楚这些变化的持久性是如何介导的。表观基因组和表转录组的变化可能是长期变化的机制之一。近年来，包括n6 -甲基腺苷（m6A）在内的RNA修饰已被证明在皮质发育中发挥重要作用，并且仅在人类m6A标记的转录本中显示与精神分裂症和自闭症相关的富集，这表明这种修饰与神经发育障碍之间存在联系（Yoon等人，2017）。m6A通过甲基转移酶写入复合物（METTL3和METTL14）沉积在转录本上，并被擦除剂（FTO和ALKBH5）去除，并且在功能上该标记与RNA周转有关（Roundtree等人，2017）。虽然书写复合物的丢失会导致细胞周期延长和神经祖细胞的增殖（Yoon等人，2017），但据我们所知，橡皮擦丢失的影响尚未得到广泛研究。此外，免疫学领域最近的研究表明，病毒和细胞RNA上的m6A修饰在调节宿主对病毒感染的反应中发挥作用（McFadden & Horner, 2021）。一些研究表明，m6A的变化可能参与了免疫挑战下METTL3表达上调的小胶质细胞炎症反应机制（Wen et al., 2020）。在这种情况下，像ALKBH5这样的擦除剂对这种情况下的反应具有修饰功能是可行的，然而，擦除剂的丢失如何影响小胶质细胞对免疫挑战的反应仍有待研究。该项目旨在探索m6A水平的变化是否会增加免疫攻击后神经发育疾病的易感性，使用ipsc衍生的神经元和小胶质样细胞作为早期人类大脑发育的模型。

Maternal immune activation (MIA) is a known environmental risk factor for neurodevelopmental disorders, established through both epidemiological studies and animal models (Brown & Meyer, 2018). Previous work in the supervisor labs has shown that the effects of cytokine exposure can also be successfully modelled in human induced pluripotent stem cell (iPSC)-derived neurons and these cells exposed to interferon gamma (IFNY) show persistent gene expression changes (Warre-Cornish et al., 2020). However, it remains unknown how the persistency of these changes is mediated.Epigenome and epitranscriptome changes might be among the mechanisms underlying the long-term changes. In the recent years, RNA modifications, including N6-methyladenosine (m6A), have been shown to play important roles in cortical development and exclusively in human m6A tagged transcripts showed enrichment for associations with schizophrenia and autism, suggesting a link between this modification and neurodevelopmental disorders (Yoon et al., 2017). m6A gets deposited on the transcripts by the methyltransferase writer complex (METTL3 and METTL14) and removed by the erasers (FTO and ALKBH5) and functionally this mark is associated with RNA turnover (Roundtree et al., 2017). While loss of the writers complex leads to extended cell cycle and proliferation of neural progenitors (Yoon et al., 2017), to the best of our knowledge, the effects of the eraser loss have not been extensively investigated.Furthermore, recent studies in the immunology field suggest that m6A modifications on viral and cellular RNA play a role in modulating host responses to viral infection (McFadden & Horner, 2021). Some studies have shown that changes in m6A may contribute to the mechanisms microglial inflammatory responses with METTL3 expression is upregulated in response to immune challenge (Wen et al., 2020). In this case, it is feasible that the erasers like ALKBH5 have a modifying function on the response in this case, however, how the eraser loss affects microglia response to immune challenge remains to be investigated. This project aims to explore whether changes in m6A levels increase the susceptibility to neurodevelopmental disease after an immune challenge, using iPSC-derived neurons and microglia like cells as a model for early human brain development.