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铁杆木虫 (小有名气)

[交流] Neuron:神经祖细胞Notch信号调节

胚胎中的神经祖细胞依靠Notch效应子基因Hes1的表达,然而,长时间高水平的
Hes1基因表达会抑制神经祖细胞的增殖和分化。

在4月10日的《神经元》(Neuron)杂志上,Shimojo等人就这个问题,用实时
成像的方法发现,Hes1基因在神经祖细胞中的表达呈动态振荡的形式。进一步
的研究证实,持续过度的Hes1基因表达会抑制基因、Notch配体和细胞周期调节
子的表达。这说明正是Hes1基因的振荡表达决定了颈板等基因的适量表达。

令人吃惊的是,神经祖细胞中的颈板基因Neurogenin2(Ngn2)和Notch配体De
lta-like1(Dll1)也在以振荡的方式表达并抑制Notch信号。通常人们认为No
tch信号可以诱导神经细胞的分化,引发Hes1基因的下调以及Ngn2和Dll1基因的
上调。

因此,Shimojo等的研究结果表明,Hes1基因的振荡表达调节着Ngn2和Dll1基因
的振荡表达。而Ngn2和Dll1基因的振荡表达又通过引导Notch信号的共活化来保
证神经祖细胞的正常运转。(科学网 武彦文/编译)

推荐原始出处:

(Neuron),Vol 58, 52-64, 10 April 2008,Hiromi Shimojo, Ryoichiro
Kageyama

Oscillations in Notch Signaling Regulate Maintenance of Neural Proge
nitors

Hiromi Shimojo, Toshiyuki Ohtsuka, and Ryoichiro Kageyama

Expression of the Notch effector gene Hes1 is required for maintenan
ce of neural progenitors in the embryonic brain, but persistent and
high levels of Hes1 expression inhibit proliferation and differentia
tion of these cells. Here, by using a real-time imaging method, we f
ound that Hes1 expression dynamically oscillates in neural progenito
rs. Furthermore, sustained overexpression of Hes1 downregulates expr
ession of proneural genes, Notch ligands, and cell cycle regulators,
suggesting that their proper expression depends on Hes1 oscillation
. Surprisingly, the proneural gene Neurogenin2 (Ngn2) and the Notch
ligand Delta-like1 (Dll1) are also expressed in an oscillatory manne
r by neural progenitors, and inhibition of Notch signaling, a condit
ion known to induce neuronal differentiation, leads to downregulatio
n of Hes1 and sustained upregulation of Ngn2 and Dll1. These results
suggest that Hes1 oscillation regulates Ngn2 and Dll1 oscillations,
which in turn lead to maintenance of neural progenitors by mutual a
ctivation of Notch signaling.


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