The mammalian Dlx genes encode homeobox‐type transcription factors and are physically organized as convergent bigene clusters. The paired Dlx genes share tissue specificity in the expression profile. Genetic regulatory mechanisms, such as intergenic enhancer sharing between paired Dlx genes, have been proposed to explain this conservation of bigene structure. All mammalian Dlx genes have expression and function in developing craniofacial structures, especially in the first and second pharyngeal arches (branchial arches). Each Dlx cluster (Dlx1/2, Dlx3/4 , and Dlx5/6 ) has overlapping, nested expression in the branchial arches which is called the “Dlx code” and plays a key role in organizing craniofacial structure and evolution. Here we summarize cis‐regulatory studies on branchial arch expression of the three Dlx bigene clusters and show some shared characteristics among the clusters, including cis‐regulatory motifs, TAD (Topologically Associating Domain) boundaries, CTCF loops, and distal enhancer landscapes, together with a molecular condensate model for activation of the Dlx bigene cluster.

中文翻译：

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l弓Dlx基因系统的调控景观：Dlx双烯簇和进化之间的共同特征。

哺乳动物的Dlx基因编码同源异型盒型转录因子，并在物理上组织成会聚的双烯簇。配对的Dlx基因在表达谱中共享组织特异性。已经提出遗传调控机制，例如成对的Dlx基因之间的基因间增强子共享，来解释这种双烯结构的保守性。所有哺乳动物的Dlx基因在发育的颅面结构中都有表达和功能，特别是在第一和第二咽弓（支弓）中。每个DLX簇（Dlx1 / 2，Dlx3 / 4，和DLX5 / 6）在the弓中有重叠的嵌套表达，称为“ Dlx码”，在组织颅面结构和进化中起关键作用。在这里，我们总结了顺式调控研究对三个的鳃弓表达DLX bigene集群，并显示集群中的一些共同特征，包括顺式调控图案，TAD（拓扑缔合域）的边界，CTCF循环和远端增强景观，加上分子缩合物模型用于激活DLX bigene集群。