Robinson G W, Wray S, Mahon K A
Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
New Biol. 1991 Dec;3(12):1183-94.
The homeobox genes of Drosophila perform key functions in embryonic pattern formation, and their vertebrate counterparts may play similar developmental roles. Using polymerase chain reaction technology, we have identified four murine homologs of the Drosophila Distal-less homeobox gene that are expressed in midgestation embryos. The homeodomains encoded by these genes vary considerably from other known homeodomain sequences and represent a new family of vertebrate homeobox genes. We isolated a cDNA for one of these genes (Dlx-2) and studied its expression by in situ hybridization from 8.5 days postcoitum (pc) until postnatal day 1. Dlx-2 shows a restricted pattern of expression in the ventral forebrain, extending from the olfactory bulb to the ventral diencephalon. This domain of expression may delineate an ontogenetically defined subdivision within the forebrain. The murine Distal-less genes are the first homeobox genes described whose expression in the central nervous system is exclusively restricted to the forebrain. Thus, the Distal-less genes may contribute missing positional cues not provided by the previously identified vertebrate homeobox genes.
果蝇的同源异型框基因在胚胎模式形成中发挥关键作用，其脊椎动物的对应基因可能具有相似的发育作用。利用聚合酶链反应技术，我们已鉴定出果蝇远端缺失同源异型框基因的四个小鼠同源基因，它们在妊娠中期胚胎中表达。这些基因编码的同源结构域与其他已知的同源结构域序列有很大差异，代表了脊椎动物同源异型框基因的一个新家族。我们分离出其中一个基因（Dlx-2）的cDNA，并通过原位杂交研究了从受精后8.5天（pc）到出生后第1天其表达情况。Dlx-2在前脑腹侧呈现出受限的表达模式，从嗅球延伸至腹侧间脑。这种表达区域可能划定了前脑内一个在个体发生学上定义的亚区。小鼠远端缺失基因是首批被描述的同源异型框基因，其在中枢神经系统中的表达仅局限于前脑。因此，远端缺失基因可能提供了先前鉴定的脊椎动物同源异型框基因未提供的缺失位置线索。
