Jan Y N, Jan L Y
Howard Hughes Medical Institute, University of California, San Francisco 94143-0724.
Trends Neurosci. 1990 Dec;13(12):493-8. doi: 10.1016/0166-2236(90)90083-m.
The nervous system contains a diverse group of cells. Specification of the correct cell fate is obviously important for the proper function of the nervous system, yet how are the fates of different neurons determined during development? Very little is known about the underlying molecular mechanisms used in the mammalian nervous system. How, for example, are certain cells directed to form pyramidal cells rather than local interneurons? In the fruit fly Drosophila melanogaster, and the nematode Caenorhabditis elegans, some progress has been made in studying neuronal fate determination. For instance, in Drosophila, a number of genes acting at different levels have been found to control this process. They function to (1) endow a subset of the ectodermal cells in the early embryo with the potential to become neuronal precursors, (2) commit some of these cells to the fate of neuronal precursors, (3) specify the identity of these neuronal precursors, and (4) specify the identity of the individual progeny cells of a neuronal precursor. In this review, we discuss first the rationale of the genetic approach, then outline the working hypothesis and, finally, briefly describe the genes known to be involved in the formation of the sensory nervous system in Drosophila. We also discuss the prospects for extrapolating these molecular mechanisms and principles to vertebrate and invertebrate neural development.
神经系统包含多种不同类型的细胞。确定正确的细胞命运对于神经系统的正常功能显然至关重要，然而在发育过程中不同神经元的命运是如何被决定的呢？对于哺乳动物神经系统中所使用的潜在分子机制，我们知之甚少。例如，某些细胞是如何被引导形成锥体细胞而非局部中间神经元的呢？在果蝇黑腹果蝇和线虫秀丽隐杆线虫中，在研究神经元命运决定方面已经取得了一些进展。例如，在果蝇中，已经发现一些在不同水平起作用的基因来控制这个过程。它们的作用是：（1）赋予早期胚胎中外胚层细胞的一个子集成为神经元前体的潜能；（2）使这些细胞中的一些确定为神经元前体的命运；（3）确定这些神经元前体的身份；（4）确定神经元前体的单个子代细胞的身份。在这篇综述中，我们首先讨论遗传方法的基本原理，然后概述工作假设，最后简要描述已知参与果蝇感觉神经系统形成的基因。我们还讨论了将这些分子机制和原理外推到脊椎动物和无脊椎动物神经发育的前景。
