Transcriptional upregulation of the C. elegans Hox gene lin-39 during vulval cell fate specification.
Transcriptional upregulation of the C. elegans Hox gene lin-39 during vulval cell fate specification.
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外阴细胞命运规范过程中线虫 Hox 基因 lin-39 的转录上调。
DOI：
10.1016/j.mod.2005.11.003
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
Eisenmann,DavidM
中科院分区：
文献类型：
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作者：
Wagmaister,JavierA;Gleason,JulieE;Eisenmann,DavidM
细胞外信号通路和转录调控网络在发育过程中发挥作用，以指定后生动物细胞的命运。在秀丽隐杆线虫外阴发育过程中，三种外阴前体细胞（VPC）的特化需要Wnt、Notch和Ras信号通路的活性以及Hox基因lin-39的功能。LIN-39蛋白水平在VPC中通过Wnt和Ras信号传导调节。具体地，Ras信号传导的激活导致在VPC命运特化时P6.p中LIN-39蛋白的增加。我们希望了解lin-39通过这些途径的调节。我们首先表明，LIN-39是MAP激酶在体外的目标，这表明Ras依赖的LIN-39的上调可能是介导的后炎症。为了验证这一想法，我们创建了包括整个lin-39基因组区域的转录和翻译lin-39：：GFP融合体，允许在活体动物中观察lin-39表达。报告基因在之前通过LIN-39抗体染色观察到的大多数（如果不是全部）表达位点中表达GFP。我们使用这些构建体来显示，在外阴诱导时，lin-39：：GFP报告基因在P6. p中均上调，表明先前检测到的高水平LIN-39蛋白的积累对应于lin-39表达的转录上调。lin-39的这种转录上调依赖于Ras信号传导。我们测试了VPC中Ras信号下游作用的几种转录因子的需要，发现P6 β上调需要转录因子LIN-1和LIN-25，但似乎不依赖于LIN-31、SEM-4、EOR-1和EOR-2。最后，我们发现当Wnt通路过度激活时，转录因子lin-39：GFP增加，表明Wnt途径也在转录水平上调节lin-39。
Extracellular signaling pathways and transcriptional regulatory networks function during development to specify metazoan cell fates. During Caenorhabditis elegans vulval development, the specification of three vulval precursor cells (VPCs) requires the activity of Wnt, Notch, and Ras signaling pathways, and function of the Hox gene lin-39. LIN-39 protein levels are regulated in the VPCs by both Wnt and Ras signaling. In particular, activation of Ras signaling leads to an increase in LIN-39 protein in P6.p at the time of VPC fate specification. We wish to understand the regulation of lin-39 by these pathways. We first show that LIN-39 is a target for MAP kinase in vitro, suggesting that the Ras-dependent LIN-39 upregulation could be mediated post-translationally. To test this idea, we created transcriptional and translational lin-39::GFP fusions that include the entire lin-39 genomic region, allowing observation of lin-39 expression in live animals. The reporters express GFP in most, if not all, sites of expression previously observed by LIN-39 antibody staining. We used these constructs to show that at the time of vulval induction both lin-39::GFP reporters are upregulated in P6.p, indicating that the accumulation of high levels of LIN-39 protein detected previously corresponds to transcriptional upregulation of lin-39 expression. This transcriptional upregulation of lin-39 is dependent on Ras signaling. We tested the requirement for several transcription factors acting downstream of Ras signaling in the VPCs, and found that P6.p upregulation requires the transcription factors LIN-1 and LIN-25, but appears to be independent of LIN-31, SEM-4, EOR-1 and EOR-2.Finally, we found that when the Wnt pathway is over activated, expression from the transcriptional lin-39::GFP increases, suggesting that the Wnt pathway also regulates lin-39 at the transcriptional level.