Yokouchi Y, Sakiyama J, Kuroiwa A
Department of Molecular Biology, School of Science, Nagoya University, Japan.
Dev Biol. 1995 May;169(1):76-89. doi: 10.1006/dbio.1995.1128.
To elucidate the molecular mechanism for determining the positional specificity and morphogenesis of the chicken digestive tract, we analyzed expression patterns of Hox genes during development of the digestive tract, focusing on the Abd-B subfamily genes of the HoxA cluster, Hoxa-9,-10,-11, and -13. Region-specific expression of these genes was found in the visceral mesoderm. In early development, before commencement of hindgut closure, they were expressed in a Russian doll pattern with the more 5' located gene on the cluster showing the more posterior restricted expression domain. At middle stage, when hindgut closure had occurred and morphological subdivision of the hindgut was gradually becoming distinct, the expression domains of each gene became mutually exclusive and restricted to the subdivisions; i.e., Hoxa-9 in the posterior part of the small intestine and the ceca, Hoxa-10 in the ceca, Hoxa-11 in the ceca, the large intestine, and the cloaca, and Hoxa-13 in the cloaca. At later stages, when the bilateral branches of the ceca had formed, the overlapping expression domains of Hoxa-10 and -11 were strongly correlated with the budding processes of the ceca. These observations suggest the possibility that Hox genes are responsible for determination of the position-specific differentiation of the visceral mesoderm of the digestive system and regulate the budding processes of the ceca.
为阐明决定鸡消化道位置特异性和形态发生的分子机制，我们分析了消化道发育过程中Hox基因的表达模式，重点关注HoxA基因簇的Abd - B亚家族基因Hoxa - 9、- 10、- 11和- 13。这些基因在内脏中胚层呈现区域特异性表达。在发育早期，后肠闭合开始之前，它们以俄罗斯套娃模式表达，基因簇上位置越靠5'端的基因，其表达域越靠后。在中期，当后肠闭合发生且后肠的形态细分逐渐变得明显时，每个基因的表达域相互排斥并局限于细分区域；即，Hoxa - 9在小肠后部和盲肠中表达，Hoxa - 10在盲肠中表达，Hoxa - 11在盲肠、大肠和泄殖腔中表达，Hoxa - 13在泄殖腔中表达。在后期，当盲肠的双侧分支形成时，Hoxa - 10和- 11的重叠表达域与盲肠的出芽过程密切相关。这些观察结果表明，Hox基因可能负责确定消化系统内脏中胚层的位置特异性分化，并调节盲肠的出芽过程。
