Neural crest survival and differentiation in zebrafish depends on mont blanc/tfap2a gene function
Neural crest survival and differentiation in zebrafish depends on mont blanc/tfap2a gene function
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DOI：
10.1242/dev.01033
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发表时间：
2004-04-01
期刊：
影响因子：
4.6
通讯作者：
Knapik, EW
中科院分区：
文献类型：
--
作者：
Barrallo-Gimeno, A;Holzschuh, J;Knapik, EW
神经嵴祖细胞是脊椎动物头部颅面软骨和结缔组织的主要贡献者。这些祖细胞还产生色素、神经元和神经胶质细胞谱系。为了研究神经嵴分化的分子基础，我们克隆了在mont blanc（mob（m610））突变中被破坏的基因，该基因影响所有神经嵴衍生物。使用位置候选克隆方法，我们确定了tfap 2a基因的第六个内含子的3'剪接位点内的A到G转换，其废除了编码关键蛋白质二聚化和DNA结合结构域的最后一个外显子。神经嵴的诱导和特化在mob（m610）突变胚胎中没有受到阻碍，这是由早期神经嵴特异性基因如snail 2，foxd 3和sox 10的正常表达所揭示的。此外，颅神经嵴迁移的初始阶段似乎未受干扰，而在后期阶段，咽弓2至7的颅面原基不能表达其典型的基因组（sox 9a，wnt 5a，dlx 2，hoxa 2/b2）。在mob（m610）突变胚胎中，神经嵴的神经元和神经胶质衍生物的细胞数量大大减少，表明tfap 2a是其正常发育所必需的。通过追踪神经嵴祖细胞在活的勃朗峰（MOB（M610））胚胎的命运，我们发现，在24 hpf神经嵴细胞正常迁移在第一咽弓，而耳前和耳后神经嵴细胞开始迁移，但未能下降到头部的咽部区域。TUNEL法和吖啶橙子染色显示，在tfap 2a的情况下，神经嵴细胞的一个子集不能进行终末分化和凋亡死亡。此外，在tfap 2a/mob（m610）突变胚胎中存活的神经嵴细胞正常增殖，随后分化为单个衍生物。我们的研究结果表明，tfap 2a是必不可少的开启正常的发育程序，在拱2-7和躯干神经嵴。因此，tfap 2a似乎不参与神经嵴的早期特化和细胞增殖，但它是早期分化阶段的关键调节因子，并且是神经嵴衍生细胞谱系中细胞存活所需的。
Neural crest progenitor cells are the main contributors to craniofacial cartilage and connective tissue of the vertebrate head. These progenitor cells also give rise to the pigment, neuronal and glial cell lineages. To study the molecular basis of neural crest differentiation, we have cloned the gene disrupted in the mont blanc (mob(m610)) mutation, which affects all neural crest derivatives. Using a positional candidate cloning approach we identified an A to G transition within the 3' splice site of the sixth intron of the tfap2a gene that abolishes the last exon encoding the crucial protein dimerization and DNA-binding domains. Neural crest induction and specification are not hindered in mob(m610) mutant embryos, as revealed by normal expression of early neural crest specific genes such as snail2, foxd3 and sox10. In addition, the initial stages of cranial neural crest migration appear undisturbed, while at a later phase the craniofacial primordia in pharyngeal arches two to seven fail to express their typical set of genes (sox9a, wnt5a, dlx2, hoxa2/b2). In mob(m610) mutant embryos, the cell number of neuronal and glial derivatives of neural crest is greatly reduced, suggesting that tfap2a is required for their normal development. By tracing the fate of neural crest progenitors in live mont blanc (mob(m610)) embryos, we found that at 24 hpf neural crest cells migrate normally in the first pharyngeal arch while the preotic and postotic neural crest cells begin migration but fail to descend to the pharyngeal region of the head. TUNEL assay and Acridine Orange staining revealed that in the absence of tfap2a a subset of neural crest cells are unable to undergo terminal differentiation and die by apoptosis. Furthermore, surviving neural crest cells in tfap2a/mob(m610) mutant embryos proliferate normally and later differentiate to individual derivatives. Our results indicate that tfap2a is essential to turn on the normal developmental program in arches 2-7 and in trunk neural crest. Thus, tfap2a does not appear to be involved in early specification and cell proliferation of neural crest, but it is a key regulator of an early differentiation phase and is required for cell survival in neural crest derived cell lineages.