Systemic and local cues drive neural stem cell niche remodelling during neurogenesis in Drosophila.

Pauline Spéder,Andrea H Brand

doi:10.7554/elife.30413

Abstract

Successful neurogenesis requires adequate proliferation of neural stem cells (NSCs) and their progeny, followed by neuronal differentiation, maturation and survival. NSCs inhabit a complex cellular microenvironment, the niche, which influences their behaviour. To ensure sustained neurogenesis, niche cells must respond to extrinsic, environmental changes whilst fulfilling the intrinsic requirements of the neurogenic program and adapting their roles accordingly. However, very little is known about how different niche cells adjust their properties to such inputs. Here, we show that nutritional and NSC-derived signals induce the remodelling of Drosophila cortex glia, adapting this glial niche to the evolving needs of NSCs. First, nutrition-induced activation of PI3K/Akt drives the cortex glia to expand their membrane processes. Second, when NSCs emerge from quiescence to resume proliferation, they signal to glia to promote membrane remodelling and the formation of a bespoke structure around each NSC lineage. The remodelled glial niche is essential for newborn neuron survival.

Highlights

Stem cell niches support the normal function of stem cells (Bjornsson et al, 2015; Lander et al, 2012)
An important question has been whether the cortex glial chamber is present throughout postembryonic life, enclosing neural stem cells (NSCs) lineages from quiescence to proliferation (Sousa-Nunes et al, 2011; Limmer and Klambt, 2014), or whether the cortex glial niche evolves over time (Pereanu et al, 2005)
We demonstrate that the cortex glial niche cells are able to integrate both external, nutritional signals and local NSC behaviour, triggering remodelling of their architecture

Summary

Introduction

Stem cell niches support the normal function of stem cells (Bjornsson et al, 2015; Lander et al, 2012). The mammalian NSC niche displays an intricate and compact architecture made up of diverse cell populations, including neurons, astrocytes, blood vessels forming part of the blood-brain barrier (BBB) and resident immune cells, the microglia (Bjornsson et al, 2015; Silva-Vargas et al, 2013). Both mechanical and diffusible signals pass between cell populations to influence NSCs (Bjornsson et al, 2015; Silva-Vargas et al, 2013). How niche cells respond to NSC inputs and how these interactions respond to external pressures remain to be determined

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Results

Conclusion