Wang X, Chu L T, He J, Emelyanov A, Korzh V, Gong Z
Department of Biological Sciences, National University of Singapore, Singapore 119260, Singapore.
Gene. 2001 Sep 5;275(1):47-55. doi: 10.1016/s0378-1119(01)00648-5.
Many basic helix-loop-helix transcriptional factors play important roles in vertebrate neurogenesis. Among them, Neurogenins act as determination factors and initiate the expression of differentiation genes such as neuroD and other neurogenic genes. Here we describe a zebrafish cDNA (neurogenin3 or ngn3) encoding a novel member of the Neurogenin family closest to mouse Ngn3 and human NGN3. Using a zebrafish radiation hybrid panel, ngn3 was mapped to zebrafish linkage group 13 and the region displayed a conserved synteny with the region of human chromosome 10 containing NGN3. As judged by RT-PCR and whole-mount in situ hybridization, ngn3 expression in zebrafish started much later than other neurogenin genes, at only around 24 h post-fertilization (hpf) and with a higher level of expression on the left side of the anterio-ventral diencephalon. Later at 48 hpf, ngn3 expression was detected in a small number of cells in the tuberal hypothalamus. Unlike Ngn3 in the mouse, zebrafish ngn3 mRNAs were not detected in developing pancreas and spinal cord. Genomic Southern blot hybridization suggested that a closely related sequence is present in the zebrafish genome and the hypothetical gene might result from the recent genome duplication in certain teleost lineage and share the function of the common ancestor with the currently characterized ngn3.
许多基本的螺旋-环-螺旋转录因子在脊椎动物神经发生过程中发挥着重要作用。其中，神经生成素作为决定性因子，启动诸如NeuroD等分化基因以及其他神经发生基因的表达。在此，我们描述了一种斑马鱼cDNA（神经生成素3或ngn3），它编码神经生成素家族的一个新成员，与小鼠Ngn3和人类NGN3最为接近。利用斑马鱼辐射杂种细胞系，ngn3被定位到斑马鱼连锁群13上，该区域与包含NGN3的人类10号染色体区域显示出保守的同线性。通过逆转录聚合酶链反应（RT-PCR）和整体原位杂交判断，斑马鱼中ngn3的表达比其他神经生成素基因开始得晚得多，仅在受精后约24小时（hpf）开始，并且在前腹侧间脑左侧表达水平较高。在稍后的48 hpf时，在结节下丘脑的少数细胞中检测到ngn3的表达。与小鼠中的Ngn3不同，在发育中的胰腺和脊髓中未检测到斑马鱼ngn3 mRNA。基因组Southern印迹杂交表明，斑马鱼基因组中存在一个密切相关的序列，该假设基因可能源于某些硬骨鱼谱系最近的基因组重复事件，并与当前鉴定的ngn3共享共同祖先的功能。
