Commissureless is required both in commissural neurones and midline cells for axon guidance across the midline.
Commissureless is required both in commissural neurones and midline cells for axon guidance across the midline.
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作者：
M. Georgiou;G. Tear
在缺乏无连合 (Comm) 功能的情况下，轴突无法延伸穿过中枢神经系统中线。 Comm 下调 Roundabout (Robo)（中线排斥狭缝的受体）的水平，以允许轴突穿过中线。 comm 转录物在中线神经胶质细胞中高水平表达，并且 Comm 蛋白在中线的轴突上积累。这导致了这样的假设：Comm 从中线神经胶质细胞移动到轴突，从而降低 Robo 水平。我们发现中线细胞中 Comm 的表达无法挽救 Comm 表型，并且 Comm 的标记版本不会转移到轴突。对 Comm 蛋白表达的重新检查和靶向 RNA 干扰的使用表明，正确的中线交叉需要 Comm 在连合轴突和中线神经胶质细胞中表达。我们认为，Comm 蛋白在中线的积累在空间上限制了 Comm 的活性，并阻止它在中枢神经系统的对侧活跃。
In the absence of Commissureless (Comm) function, axons are unable to extend across the central nervous system midline. Comm downregulates levels of Roundabout (Robo), a receptor for the midline repellent Slit, in order to allow axons to cross the midline. comm transcript is expressed at high levels in the midline glia and Comm protein accumulates on axons at the midline. This has led to the hypothesis that Comm moves from the midline glia to the axons, where it can reduce Robo levels. We have found that expression of Comm in the midline cells is unable to rescue the comm phenotype and that tagged versions of Comm are not transferred to axons. A re-examination of Comm protein expression and the use of targeted RNA interference reveal that correct midline crossing requires that Comm is expressed in the commissural axons and midline glia. We suggest that accumulation of Comm protein at the midline spatially limits Comm activity and prevents it from being active on the contralateral side of the central nervous system.