Cellular dataset for: The anterior Hox gene ceh-13 and elt-1/GATA activate the posterior Hox genes nob-1 and php-3 to specify posterior lineages in the C. elegans embryo

Hox transcription factors play a conserved role in specifying positional
identity during animal development, with posterior Hox genes typically
repressing the expression of more anterior Hox genes. Here, we dissect the
regulation of the posterior Hox genes nob-1 and php-3 in the nematode C.
elegans. We show that nob-1 and php-3 are co-expressed in
gastrulation-stage embryos in cells that previously expressed the anterior
Hox gene ceh-13. This expression is controlled by several partially
redundant transcriptional enhancers. Surprisingly, these enhancers require
ceh-13 for expression, providing an example of an anterior Hox gene
positively regulating a posterior Hox gene. Several other regulators
including elt-1/GATA, ceh-20/ceh-40/Pbx, unc-62/Meis, pop-1/TCF,
ceh-36/Otx and unc-30/Pitx also act positively through nob-1/php-3
enhancers. We identified defects in both cell position and cell division
patterns in ceh-13 and nob-1;php-3 mutants, suggesting that these factors
regulate lineage identity in addition to positional identity. Taken
together, our results highlight the complexity and remarkable flexibility
of Hox gene regulation and function.

同源盒转录因子（Hox transcription factors）在动物发育过程中，对确立细胞位置同一性发挥着保守的调控作用，通常后部Hox基因会抑制前部Hox基因的表达。本研究剖析了秀丽隐杆线虫（C. elegans）中后部Hox基因nob-1与php-3的调控机制。研究发现，nob-1与php-3会在原肠胚阶段胚胎中，于此前表达前部Hox基因ceh-13的细胞内共表达。该表达过程受多个部分冗余的转录增强子调控。令人意外的是，这些增强子的功能依赖ceh-13方可实现，这为前部Hox基因正向调控后部Hox基因提供了一则范例。另有包括elt-1/GATA、ceh-20/ceh-40/Pbx、unc-62/Meis、pop-1/TCF、ceh-36/Otx以及unc-30/Pitx在内的多种调控因子，也可通过nob-1/php-3的增强子发挥正向调控作用。研究人员在ceh-13及nob-1;php-3突变体中，观察到细胞位置与细胞分裂模式均存在异常，这表明这些因子除调控位置同一性外，还可调控谱系同一性。综上，本研究结果凸显了Hox基因调控与功能的复杂性及显著的灵活性。