Molecular Analysis of the A63 Gene That Is Essential for Drosophila Neurogenesis

果蝇的中枢神经系统包括大量的神经元，这些神经元起源于神经干细胞，神经母细胞。它们产生一系列特定的神经节母细胞，每一个母细胞都分裂成一对神经元。神经元的身份似乎是由神经母细胞和神经元出生的谱系决定的。虽然对单个神经元正确获得其身份的分子过程知之甚少，但已表明发育中的中枢神经系统中的细胞命运决定涉及已知在早期胚胎发生中控制节段结构建立的节段基因。我们通过增强子陷阱方法筛选了控制神经发生的基因突变，并确定了神经发生所需的pros基因。prosfunction的缺失导致中枢神经系统神经形态的致命缺陷，以及分段基因fushitarazu（ftz）、even-skipped（eve）和enrailed（en）的异常表达模式，导致某些神经元轴突的错误寻路。为了了解pros的功能，我们分离了pros基因。pros编码含有同源结构域样序列的核蛋白。在中枢神经系统的神经元谱系中，在神经节母细胞中特异性检测到pros蛋白，尽管其亲本成神经细胞已开始表达显著水平的pros转录物，表明pros表达的转录后控制。我们的研究结果提示，在神经元细胞分化中，神经节母细胞可能起着关键的作用，与前功能相关。

The Drosophila central nervous system comprises an enormous diversity of neurons that are originated from neuronal stem cells, neuroblasts. They generate a specific series of ganglion mother cells, each of which is once cleaved into a pair of neurons. Neuronal identity seems to be determined by neuroblasts from which, and by lineages through which neurons are born. While much is not known about the molecular process for individual neurons to correctly acquire their identity, it has been shown that cell fate determination in the developing central nervous system involves segmentation genes that are known to control the establishment of the segmental structure in early embryogenesis.We have screened for mutations in genes controlling neurogenesis by the enhancer trap method, and identified the prospero (pros) gene that is required for neurogenesis. Loss of pros function causes lethal defects in the neural morphology, and abnormal expression patterns of segmentation genes, fushitarazu (ftz), even-skipped (eve) and engrailed (en) in the central nervous system, resulting in wrong path finding of axons in some identified neurons. To understand how pros functions, we have isolated the pros gene. pros encodes a nuclear protein containing a homeodomain-like sequence. In neuronal lineages of the central nervous system, pros protein is specifically detected in ganglion mother cells, although their parental neuroblasts have begun expressing a significant level of pros transcripts, suggesting a post-transcriptional control of pros expression. Our results provoke that in neuronal cell differentiation ganglion mother cells might play a pivotal role associating with the pros function.