Multiple transcription factors directly regulate Hox gene lin-39 expression in ventral hypodermal cells of the C. elegans embryo and larva, including the hypodermal fate regulators LIN-26 and ELT-6.
Multiple transcription factors directly regulate Hox gene lin-39 expression in ventral hypodermal cells of the C. elegans embryo and larva, including the hypodermal fate regulators LIN-26 and ELT-6.
复制标题
DOI：
10.1186/1471-213x-14-17
复制
发表时间：
2014-05-13
影响因子：
--
通讯作者：
Eisenmann DM
中科院分区：
文献类型：
--
作者：
Liu WJ;Reece-Hoyes JS;Walhout AJ;Eisenmann DM
Hox基因编码区域命运规范在早期后生动物发育的主调节器。关于果蝇和脊椎动物中Hox基因表达的启动和调控，我们知道的很多，但在非节肢动物无脊椎动物模型系统中，C。优美的梭线虫Hox基因lin-39是在包括外阴前体细胞（VPCs）在内的中间体区域中正确命运特化所必需的。为了更好地了解lin-39的调控和功能，我们的目的是确定VPC中lin-39表达所必需的转录因子，特别是寻找启动胚胎中lin-39表达的因子。我们使用酵母单杂交（Y1 H）方法筛选与lin-39区13个片段结合的因子：12个片段含有C. elegans和其他两种线虫物种，而已知一个片段在产生VPC的细胞的早期胚胎中驱动报告基因表达。在酵母中鉴定了16个与8个lin-39基因组片段结合的转录因子，我们通过验证它们在体外的物理相互作用来表征几个因子，并表明它们的功能降低会导致lin-39水平和lin-39：：GFP报告基因在体内表达的改变。孤儿核激素受体NHR-43、皮下命运调节因子LIN-26和加塔因子ELT-6这三个因子正调节lin-39在VPC的胚胎前体中的表达。特别是，ELT-6与驱动GFP在早期胚胎中表达的增强子相互作用，并且我们鉴定的ELT-6位点对于适当的胚胎表达是必需的。这三个因子与因子ZTF-17、BED-3和TBX-9一起沿着也正调节幼虫VPC中lin-39的表达。这些结果显着扩大了已知的直接结合和调节lin-39表达的因子的数量，确定了胚胎中lin-39表达所需的第一个因子，并暗示了涉及加塔因子的正反馈机制，该机制维持了lin-39在外阴谱系中的表达。这项工作表明，在其他生物中，Hox基因表达的调控在C。elegans是复杂的，冗余的和健壮的。
Hox genes encode master regulators of regional fate specification during early metazoan development. Much is known about the initiation and regulation of Hox gene expression in Drosophila and vertebrates, but less is known in the non-arthropod invertebrate model system, C. elegans. The C. elegans Hox gene lin-39 is required for correct fate specification in the midbody region, including the Vulval Precursor Cells (VPCs). To better understand lin-39 regulation and function, we aimed to identify transcription factors necessary for lin-39 expression in the VPCs, and in particular sought factors that initiate lin-39 expression in the embryo. We used the yeast one-hybrid (Y1H) method to screen for factors that bound to 13 fragments from the lin-39 region: twelve fragments contained sequences conserved between C. elegans and two other nematode species, while one fragment was known to drive reporter gene expression in the early embryo in cells that generate the VPCs. Sixteen transcription factors that bind to eight lin-39 genomic fragments were identified in yeast, and we characterized several factors by verifying their physical interactions in vitro, and showing that reduction of their function leads to alterations in lin-39 levels and lin-39::GFP reporter expression in vivo. Three factors, the orphan nuclear hormone receptor NHR-43, the hypodermal fate regulator LIN-26, and the GATA factor ELT-6 positively regulate lin-39 expression in the embryonic precursors to the VPCs. In particular, ELT-6 interacts with an enhancer that drives GFP expression in the early embryo, and the ELT-6 site we identified is necessary for proper embryonic expression. These three factors, along with the factors ZTF-17, BED-3 and TBX-9, also positively regulate lin-39 expression in the larval VPCs. These results significantly expand the number of factors known to directly bind and regulate lin-39 expression, identify the first factors required for lin-39 expression in the embryo, and hint at a positive feedback mechanism involving GATA factors that maintains lin-39 expression in the vulval lineage. This work indicates that, as in other organisms, the regulation of Hox gene expression in C. elegans is complicated, redundant and robust.