生物谷报道：本期Nature报道了在体研究静息状态的神经干细胞对Sonic hedgehog （SHH）信号的反应机制。这为揭示为什么成体干细胞能在组织内终生存在，但并不会出现增殖或分化的机理。
Sonic hedgehog (Shh) has been implicated in the ongoing neurogenesis in postnatal rodent brains1, 2. Here we adopted an in vivo genetic fate-mapping strategy, using Gli1 (GLI-Kruppel family member) as a sensitive readout of Shh activity, to systematically mark and follow the fate of Shh-responding cells in the adult mouse forebrain. We show that initially, only a small population of cells (including both quiescent neural stem cells and transit-amplifying cells) responds to Shh in regions undergoing neurogenesis. This population subsequently expands markedly to continuously provide new neurons in the forebrain. Our study of the behaviour of quiescent neural stem cells provides in vivo evidence that they can self-renew for over a year and generate multiple cell types. Furthermore, we show that the neural stem cell niches in the subventricular zone and dentate gyrus are established sequentially and not until late embryonic stages.
原文来源：
Sohyun Ahn and Alexandra L. Joyner. In vivo analysis of quiescent adult neural stem cells responding to Sonic hedgehog. Nature 437, 894-897 (6 October 2005)
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