Harris R, Sabatelli L M, Seeger M A
Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
Neuron. 1996 Aug;17(2):217-28. doi: 10.1016/s0896-6273(00)80154-3.
Netrins are chemotropic guidance signals that play important roles in circumferential axon guidance in C. elegans and in the developing vertebrate spinal cord. We have identified two Drosophila homologs of this protein family (Netrin-A and Netrin-B). Both Netrins are dynamically expressed throughout embryogenesis, including CNS midline expression at the time of commissure formation. Both Netrin genes map close to each other on the X chromosome, and embryos deficient for this region exhibit defects in commissure formation. This CNS phenotype can be rescued by expression of either Netrin at the CNS midline, confirming an important role for Drosophila Netrins in commissural growth cone guidance. A localized source of Netrin protein at the midline is apparently important for function, since ectopic expression of either Netrin throughout the CNS results in phenotypic defects similar to the loss-of-function phenotype.
Netrins是化学趋向性引导信号，在秀丽隐杆线虫的圆周轴突引导以及发育中的脊椎动物脊髓中发挥重要作用。我们已经鉴定出该蛋白家族的两个果蝇同源物（Netrin-A和Netrin-B）。两种Netrins在整个胚胎发育过程中动态表达，包括在连合形成时在中枢神经系统中线的表达。两个Netrin基因在X染色体上彼此靠近定位，并且该区域缺陷的胚胎在连合形成中表现出缺陷。这种中枢神经系统表型可以通过在中枢神经系统中线表达任何一种Netrin来挽救，证实了果蝇Netrins在连合生长锥引导中的重要作用。中线处Netrin蛋白的局部来源显然对功能很重要，因为在整个中枢神经系统中异位表达任何一种Netrin都会导致与功能丧失表型相似的表型缺陷。
