BACKGROUND During mammalian cerebral cortex development, different types of projection neurons are produced in a precise temporal order and in stereotypical numbers. The mechanisms regulating timely generation of neocortex projection neurons and ensuring production in sufficient numbers of each neuronal identity are only partially understood. RESULTS Here, we show that ephrin-B2, a member of the Eph:ephrin cell-to-cell communication pathway, sets the neurogenic tempo in the neocortex. Indeed, conditional mutant embryos for ephrin-B2 exhibit a transient delay in neurogenesis and acute stimulation of Eph signaling by in utero injection of synthetic ephrin-B2 led to a transient increase in neuronal production. Using genetic approaches we show that ephrin-B2 acts on neural progenitors to control their differentiation in a juxtacrine manner. Unexpectedly, we observed that perinatal neuron numbers recovered following both loss and gain of ephrin-B2, highlighting the ability of neural progenitors to adapt their behavior to the state of the system in order to produce stereotypical numbers of neurons. CONCLUSIONS Altogether, our data uncover a role for ephrin-B2 in embryonic neurogenesis and emphasize the plasticity of neuronal production in the neocortex.

中文翻译：

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Ephrin-B2加快了新皮层中神经元的产生。

背景技术在哺乳动物大脑皮层发育期间，以精确的时间顺序和定型数量产生不同类型的投射神经元。调节新皮层投射神经元及时产生并确保产生足够数量的每种神经元身份的机制仅被部分理解。结果在这里，我们显示了Eph：ephrin细胞间通信途径的成员ephrin-B2设定了新皮层的神经发生速度。实际上，ephrin-B2的条件性突变体胚胎在神经发生中表现出短暂的延迟，并且通过子宫内注射合成的ephrin-B2引起的Eph信号的急性刺激导致神经元产生的短暂增加。使用遗传学方法，我们表明，ephrin-B2作用于神经祖细胞，以邻分泌方式控制其分化。出乎意料的是，我们观察到，ephrin-B2的丧失和获得都伴随着围产期神经元数量的恢复，突显了神经祖细胞适应其行为以产生定型数量神经元的能力。结论总之，我们的数据揭示了ephrin-B2在胚胎神经发生中的作用，并强调了新皮层中神经元产生的可塑性。