Department of Clinical and Experimental Medicine, Linkoping University, Linkoping, Sweden.
School of Biomedical Sciences, University of Queensland, St. Lucia, Queensland, Australia.
PLoS Biol. 2019 Feb 26;17(2):e3000163. doi: 10.1371/journal.pbio.3000163. eCollection 2019 Feb.
During central nervous system (CNS) development, genetic programs establish neural stem cells and drive both stem and daughter cell proliferation. However, the prominent anterior expansion of the CNS implies anterior-posterior (A-P) modulation of these programs. In Drosophila, a set of neural stem cell factors acts along the entire A-P axis to establish neural stem cells. Brain expansion results from enhanced stem and daughter cell proliferation, promoted by a Polycomb Group (PcG)->Homeobox (Hox) homeotic network. But how does PcG->Hox modulate neural-stem-cell-factor activity along the A-P axis? We find that the PcG->Hox network creates an A-P expression gradient of neural stem cell factors, thereby driving a gradient of proliferation. PcG mutants can be rescued by misexpression of the neural stem cell factors or by mutation of one single Hox gene. Hence, brain expansion results from anterior enhancement of core neural-stem-cell-factor expression, mediated by PcG repression of brain Hox expression.
在中枢神经系统 (CNS) 发育过程中，遗传程序会建立神经干细胞，并驱动干细胞和子细胞的增殖。然而，CNS 的明显前向扩张意味着这些程序的前后（A-P）调节。在果蝇中，一组神经干细胞因子沿整个 A-P 轴起作用以建立神经干细胞。脑的扩张是由于多梳组 (PcG) - >同源盒 (Hox) 同源异型网络促进了干细胞和子细胞的增殖。但是，PcG->Hox 如何沿着 A-P 轴调节神经干细胞因子的活性呢？我们发现，PcG->Hox 网络在 A-P 上创建了神经干细胞因子的表达梯度，从而驱动了增殖的梯度。PcG 突变体可以通过神经干细胞因子的异位表达或单个 Hox 基因突变来挽救。因此，脑的扩张是由于前脑核心神经干细胞因子表达的增强，这是由 PcG 对脑 Hox 表达的抑制介导的。
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