Chapman D L, Garvey N, Hancock S, Alexiou M, Agulnik S I, Gibson-Brown J J, Cebra-Thomas J, Bollag R J, Silver L M, Papaioannou V E
Department of Genetics and Development, College of Physicans and Surgeons, Columbia University, New York, New York 10032, USA.
Dev Dyn. 1996 Aug;206(4):379-90. doi: 10.1002/(SICI)1097-0177(199608)206:4<379::AID-AJA4>3.0.CO;2-F.
A novel family of genes, characterized by the presence of a region of homology to the DNA-binding domain of the Brachyury (T) locus product, has recently been identified. The region of homology has been named the T-box, and the new mouse genes that contain the T-box domain have been named T-box 1-6 (Tbx1 through Tbx6). As the basis for further study of the function and evolution of these genes, we have examined the expression of 5 of these genes, Tbx1-Tbx5, across a wide range of embryonic stages from blastocyst through gastrulation and early organogenesis by in situ hybridization of wholemounts and tissue sections. Tbx3 is expressed earliest, in the inner cell mass of the blastocyst. Four of the genes are expressed in different components of the mesoderm or mesoderm/endoderm during gastrulation (Tbx1 and Tbx3-5). All of these genes have highly specific patterns of expression during later embryogenesis, notably in areas undergoing inductive tissue interactions. In several cases there is complementary expression of different genes in 2 interacting tissues, as in the lung epithelium (Tbx1) and lung mesenchyme (Tbx2-5), and in mammary buds (Tbx3) and mammary stroma (Tbx2). Tbx1 shows very little overlap in the sites of expression with the other 4 genes, in contrast to a striking similarity in expression between members of the 2 cognate gene sets, Tbx2/Tbx3 and Tbx4/Tbx5. This is a clear reflection of the evolutionary relationship between the 5 genes since the divergence of Tbx1 occurred long before the relatively recent divergence of Tbx2 and 3 and Tbx4 and 5 from common ancestral genes. These studies are a good indication that the T-box family of genes has important roles in inductive interactions in many stages of mammalian embryogenesis.
最近发现了一个新的基因家族，其特征是存在与短尾（T）基因座产物的DNA结合结构域具有同源性的区域。该同源区域被命名为T盒，而包含T盒结构域的新的小鼠基因被命名为T盒1-6（Tbx1至Tbx6）。作为进一步研究这些基因功能和进化的基础，我们通过对整个胚胎和组织切片进行原位杂交，检测了其中5个基因（Tbx1-Tbx5）在从囊胚到原肠胚形成以及早期器官发生的广泛胚胎阶段的表达情况。Tbx3最早在囊胚的内细胞团中表达。在原肠胚形成过程中，其中4个基因在中胚层或中胚层/内胚层的不同成分中表达（Tbx1和Tbx3-5）。所有这些基因在胚胎后期发育过程中都具有高度特异性的表达模式，特别是在经历诱导性组织相互作用的区域。在几种情况下，不同基因在两个相互作用的组织中存在互补表达，如在肺上皮（Tbx1）和肺间充质（Tbx2-5）中，以及在乳腺芽（Tbx3）和乳腺基质（Tbx2）中。与2个同源基因组（Tbx2/Tbx3和Tbx4/Tbx5）成员之间明显的表达相似性相反，Tbx1在表达位点上与其他4个基因几乎没有重叠。这清楚地反映了这5个基因之间的进化关系，因为Tbx1的分化发生在Tbx2和3以及Tbx4和5从共同祖先基因相对较近的分化之前很久。这些研究充分表明，T盒基因家族在哺乳动物胚胎发育的许多阶段的诱导性相互作用中具有重要作用。
