Li Wei, Cornell Robert A
Interdisciplinary Graduate Program in Genetics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
Dev Biol. 2007 Apr 1;304(1):338-54. doi: 10.1016/j.ydbio.2006.12.042. Epub 2006 Dec 23.
A knockdown study suggested that transcription factor AP-2 alpha (Tfap2a) is required for neural crest induction in frog embryos. However, because Tfap2a is expressed in neural crest and in presumptive epidermis, a source of signals that induce neural crest, it was unclear whether this requirement is cell autonomous. Moreover, neural crest induction occurs normally in zebrafish tfap2a and mouse Tcfap2a mutant embryos, so it was unclear if a requirement for Tfap2a in this process has been evolutionarily conserved. Here we show that zebrafish tfap2c, encoding AP-2 gamma (Tfap2c), is expressed in non-neural ectoderm including transiently in neural crest. Inhibition of tfap2c with antisense oligonucleotides does not visibly perturb development. However, simultaneous inhibition of tfap2a and tfap2c utterly prevents neural crest induction, supporting a conserved role for Tfap2-type activity in neural crest induction. Transplant studies suggest that this role is cell-autonomous. In addition, in tfap2a/tfap2c doubly deficient embryos cranial placode derivatives are reduced, although gene expression characteristic of pre-placodal domain is normal. Unexpectedly, Rohon-Beard sensory neurons, which previous studies indicated are derived from the same precursor population as neural crest, are reduced by less than half in such embryos, implying a non-neural crest origin for a subset of them.
一项基因敲低研究表明,转录因子AP - 2α(Tfap2a)是青蛙胚胎中神经嵴诱导所必需的。然而,由于Tfap2a在神经嵴和假定的表皮(诱导神经嵴的信号来源)中都有表达,所以尚不清楚这种需求是否是细胞自主的。此外,神经嵴诱导在斑马鱼tfap2a和小鼠Tcfap2a突变胚胎中正常发生,因此尚不清楚在此过程中对Tfap2a的需求是否在进化上保守。在这里,我们表明,编码AP - 2γ(Tfap2c)的斑马鱼tfap2c在非神经外胚层中表达,包括在神经嵴中短暂表达。用反义寡核苷酸抑制tfap2c不会明显干扰发育。然而,同时抑制tfap2a和tfap2c完全阻止了神经嵴诱导,支持了Tfap2型活性在神经嵴诱导中的保守作用。移植研究表明这种作用是细胞自主的。此外,在tfap2a/tfap2c双缺陷胚胎中,颅基板衍生物减少,尽管基板前结构域的基因表达特征正常。出乎意料的是,罗霍恩 - 比尔兹 sensory神经元(先前的研究表明它们与神经嵴来自相同的前体细胞群)在这类胚胎中的减少不到一半,这意味着它们的一部分起源于非神经嵴。 (注:“Rohon-Beard sensory neurons”中“sensory”前的单词拼写可能有误,推测可能是“Rohon-Beard”,按照推测进行了翻译,若有误请根据实际情况调整)