Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204-5001, USA.
Department of Biology, Texas A&M University, College Station, TX, 77843-3258, USA.
Dev Genes Evol. 2019 May;229(2-3):43-52. doi: 10.1007/s00427-019-00629-5. Epub 2019 Mar 1.
One of the earliest patterning events in the vertebrate neural plate is the specification of mes/r1, the territory comprising the prospective mesencephalon and the first hindbrain rhombomere. Within mes/r1, an interface of gene expression defines the midbrain-hindbrain boundary (MHB), a lineage restriction that separates the mesencephalon and rhombencephalon. wnt1 is critical to mes/r1 development and functions within the MHB as a component of the MHB gene regulatory network (GRN). Despite its importance to these critical and early steps of vertebrate neurogenesis, little is known about the factors responsible for wnt1 transcriptional regulation. In the zebrafish, wnt1 and its neighboring paralog, wnt10b, are expressed in largely overlapping patterns, suggesting co-regulation. To understand wnt1 and wnt10b transcriptional control, we used a comparative genomics approach to identify relevant enhancers. We show that the wnt1-wnt10b locus contains multiple cis-regulatory elements that likely interact to generate the wnt1 and wnt10b expression patterns. Two of 11 conserved enhancers tested show activity restricted to the midbrain and MHB, an activity that is conserved in the distantly related spotted gar orthologous elements. Three non-conserved elements also play a likely role in wnt1 regulation. The identified enhancers display dynamic modes of chromatin accessibility, suggesting controlled deployment during embryogenesis. Our results suggest that the control of wnt1 and wnt10b expression is under complex regulation involving the interaction of multiple enhancers.
脊椎动物神经板中最早的模式形成事件之一是 mes/r1 的特化，该区域包含前脑和第一个后脑菱脑节。在 mes/r1 中，基因表达的界面定义了中脑-后脑边界（MHB），这是一种谱系限制，将中脑和后脑分开。wnt1 对 mes/r1 的发育至关重要，并且在 MHB 中作为 MHB 基因调控网络（GRN）的一部分发挥作用。尽管 wnt1 对脊椎动物神经发生的这些关键和早期步骤非常重要，但对于负责 wnt1 转录调控的因素知之甚少。在斑马鱼中，wnt1 和其相邻的旁系同源物 wnt10b 以大致重叠的模式表达，表明共同调节。为了理解 wnt1 和 wnt10b 的转录控制，我们使用比较基因组学方法来鉴定相关的增强子。我们表明，wnt1-wnt10b 基因座包含多个可能相互作用以产生 wnt1 和 wnt10b 表达模式的顺式调控元件。在 11 个保守增强子中，有两个表现出仅限于中脑和 MHB 的活性，这种活性在亲缘关系较远的斑点gar 同源元件中是保守的。三个非保守元件也可能在 wnt1 调节中发挥作用。鉴定出的增强子显示出动态的染色质可及性模式，表明在胚胎发生过程中受到控制。我们的结果表明，wnt1 和 wnt10b 表达的控制受到涉及多个增强子相互作用的复杂调控。
