Rodrigues Deivid C, Kim Dae-Sung, Yang Guang, Zaslavsky Kirill, Ha Kevin C H, Mok Rebecca S F, Ross P Joel, Zhao Melody, Piekna Alina, Wei Wei, Blencowe Benjamin J, Morris Quaid, Ellis James
Program in Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada.
Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada.
Cell Rep. 2016 Oct 11;17(3):720-734. doi: 10.1016/j.celrep.2016.09.049.
A progressive increase in MECP2 protein levels is a crucial and precisely regulated event during neurodevelopment, but the underlying mechanism is unclear. We report that MECP2 is regulated post-transcriptionally during in vitro differentiation of human embryonic stem cells (hESCs) into cortical neurons. Using reporters to identify functional RNA sequences in the MECP2 3' UTR and genetic manipulations to explore the role of interacting factors on endogenous MECP2, we discover combinatorial mechanisms that regulate RNA stability and translation. The RNA-binding protein PUM1 and pluripotent-specific microRNAs destabilize the long MECP2 3' UTR in hESCs. Hence, the 3' UTR appears to lengthen during differentiation as the long isoform becomes stable in neurons. Meanwhile, translation of MECP2 is repressed by TIA1 in hESCs until HuC predominates in neurons, resulting in a switch to translational enhancement. Ultimately, 3' UTR-directed translational fine-tuning differentially modulates MECP2 protein in the two cell types to levels appropriate for normal neurodevelopment.
MECP2蛋白水平的逐步增加是神经发育过程中一个关键且受到精确调控的事件，但其潜在机制尚不清楚。我们报告称，在人胚胎干细胞（hESCs）体外分化为皮质神经元的过程中，MECP2在转录后水平受到调控。我们使用报告基因来鉴定MECP2 3' UTR中的功能性RNA序列，并通过基因操作来探索相互作用因子对内源性MECP2的作用，从而发现了调控RNA稳定性和翻译的组合机制。RNA结合蛋白PUM1和多能特异性微小RNA会使hESCs中较长的MECP2 3' UTR不稳定。因此，随着长异构体在神经元中变得稳定，3' UTR在分化过程中似乎会延长。与此同时，在hESCs中，MECP2的翻译受到TIA1的抑制，直到HuC在神经元中占主导地位，从而导致翻译增强的转变。最终，3' UTR指导的翻译微调在两种细胞类型中差异调节MECP2蛋白至适合正常神经发育的水平。
