Cobourne M T
Department of Craniofacial Development, G. K. T. Dental Institute, King's College London, London Bridge, London SE1 9RT, UK.
J Orthod. 2000 Dec;27(4):307-14. doi: 10.1093/ortho/27.4.307.
The vertebrate head is a highly complex composite structure whose morphological characteristics are controlled at the level of the gene. There is now increasing evidence for the role of gene families that encode transcription factors in determining the embryonic plan of the developing craniofacial complex. These genes act as regulators of gene transcription being intimately involved with the control of complex interactions between multiple downstream genes. Combinatorial expression of the Hox genes (a family of highly conserved master regulatory genes related to the homeotic genes of the fruitfly Drosophila) have been shown to play a definitive role in patterning distinct regions of the craniofacial complex. In the vertebrate, Hox genes pattern the hindbrain and branchial regions of the developing head up to and including structures derived from the second branchial arch. The first branchial arch and more rostral regions of the head are patterned by groups of homeobox genes more diverged from the original Hox clusters. Transgenic mice, with targeted disruptions in many of these genes, are now providing insights into the molecular mechanisms that lie behind a number of craniofacial defects seen in man.
脊椎动物的头部是一个高度复杂的复合结构，其形态特征在基因层面受到控制。现在越来越多的证据表明，编码转录因子的基因家族在决定发育中的颅面复合体的胚胎发育模式中发挥着作用。这些基因作为基因转录的调节因子，与多个下游基因之间复杂相互作用的控制密切相关。Hox基因（与果蝇同源异型基因相关的高度保守的主要调控基因家族）的组合表达已被证明在颅面复合体不同区域的模式形成中起决定性作用。在脊椎动物中，Hox基因对发育中头部的后脑和鳃区进行模式化，直至并包括源自第二鳃弓的结构。头部的第一鳃弓和更靠前的区域由与原始Hox簇差异更大的同源框基因群进行模式化。在许多这些基因中存在靶向破坏的转基因小鼠，现在正在为人类中出现的一些颅面缺陷背后的分子机制提供见解。
