Lee J E, Hollenberg S M, Snider L, Turner D L, Lipnick N, Weintraub H
Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
Science. 1995 May 12;268(5212):836-44. doi: 10.1126/science.7754368.
Basic helix-loop-helix (bHLH) proteins are instrumental in determining cell type during development. A bHLH protein, termed NeuroD, for neurogenic differentiation, has now been identified as a differentiation factor for neurogenesis because (i) it is expressed transiently in a subset of neurons in the central and peripheral nervous systems at the time of their terminal differentiation into mature neurons and (ii) ectopic expression of neuroD in Xenopus embryos causes premature differentiation of neuronal precursors. Furthermore, neuroD can convert presumptive epidermal cells into neurons and also act as a neuronal determination gene. However, unlike another previously identified proneural gene (XASH-3), neuroD seems competent to bypass the normal inhibitory influences that usually prevent neurogenesis in ventral and lateral ectoderm and is capable of converting most of the embryonic ectoderm into neurons. The data suggest that neuroD may participate in the terminal differentiation step during vertebrate neuronal development.
碱性螺旋-环-螺旋（bHLH）蛋白在发育过程中对确定细胞类型起重要作用。一种名为NeuroD（神经源性分化）的bHLH蛋白，现已被确定为神经发生的分化因子，原因如下：（i）在中枢和外周神经系统的一部分神经元终末分化为成熟神经元时，它会短暂表达；（ii）在非洲爪蟾胚胎中异位表达NeuroD会导致神经元前体过早分化。此外，NeuroD能将假定的表皮细胞转化为神经元，还可作为神经元决定基因。然而，与另一个先前确定的原神经基因（XASH-3）不同，NeuroD似乎能够绕过通常阻止腹侧和外侧外胚层神经发生的正常抑制性影响，并能够将大部分胚胎外胚层转化为神经元。这些数据表明，NeuroD可能参与脊椎动物神经元发育过程中的终末分化步骤。
