Combinatorial temporal patterning in progenitors expands neural diversity

摘要

Human outer subventricular zone (OSVZ) neural progenitors and Drosophila type II neuroblasts both generate intermediate neural progenitors (INPs) that populate the adult cerebral cortex or central complex, respectively. It is unknown whether INPs simply expand or also diversify neural cell types. Here we show that Drosophila INPs sequentially generate distinct neural subtypes, that INPs sequentially express Dichaete, Grainy head and Eyeless transcription factors, and that these transcription factors are required for the production of distinct neural subtypes. Moreover, parental type II neuroblasts also sequentially express transcription factors and generate different neuronal/ glial progeny over time, providing a second temporal identity axis. We conclude that neuroblast and INP temporal patterning axes act together to generate increased neural diversity within the adult central complex; OSVZ progenitors may use similar mechanisms to increase neural diversity in the human brain.%大脑由很多不问类型的神经细胞和胶质细胞组成，但它们的亲本神经干细胞在发育过程中是怎样产生这种多样性的基本上不清楚。来自几个方面的证据指向神经干细胞发育模式中的一个时间要素，同时本期Nature上的两篇论文也用果蝇模型说明了“时间推进”在调控级联的控制下所起的一个作用。Omer Ali Bayraktar和Chris Doe(利用果蝇幼虫的脑)与Claude Desplan及其同事(利用果蝇视觉系统)发现，神经祖细胞在产生调控蛋白的连续波时会随时间变化，从而增加它们的神经细胞和胶质细胞后代的大小及多样性。由于类似的神经祖细胞以及同源调控蛋白已在发育中的哺乳动物脑中被发现，所以这种时间模式形成方式可能也对人类新皮层的神经复杂性有贡献。