Department of Biology, Texas A&M University, College Station, Texas, USA.
Dev Dyn. 2011 Apr;240(4):898-907. doi: 10.1002/dvdy.22599. Epub 2011 Mar 7.
Vertebrate wnt8a links anteroposterior and dorsoventral axis patterning, but the regulation of wnt8a expression and its relationship to mesoderm induction and maintenance pathways is unclear. To address this, we have generated zebrafish transgenic for a modified genomic PAC clone that expresses EGFP from the wnt8a locus. The EGFP reporter transgene is expressed in a pattern nearly identical to wnt8a, including maternal deposition, expression in the ventrolateral mesoderm and in the yolk syncytial layer. Loss of function studies show that wnt8a expression is under biphasic control by Nodal and No Tail/Brachyury, whereby early phase expression is Nodal-dependent but late phase expression is Ntl/Bra dependent. EGFP fluorescence persists in cells that transcribe the reporter, thus comprising a tracer for ventrolaterally derived mesodermal lineages. We use this property to show that wnt8a expression marks Nodal-independent tail mesoderm formation and that Ntl/Bra predominantly regulates wnt8a in paraxial mesoderm progenitors.
脊椎动物 wnt8a 连接前后轴和背腹轴模式，但 wnt8a 表达的调节及其与中胚层诱导和维持途径的关系尚不清楚。为了解决这个问题，我们生成了斑马鱼的转基因品系，该品系使用一个修饰的基因组 PAC 克隆表达 EGFP 从 wnt8a 基因座。EGFP 报告基因在与 wnt8a 几乎完全相同的模式下表达，包括母体沉积、在腹侧中胚层和卵黄合胞层中的表达。功能丧失研究表明，wnt8a 的表达受到 Nodal 和 No Tail/Brachyury 的双相控制，其中早期表达依赖于 Nodal，但晚期表达依赖于 Ntl/Bra。EGFP 荧光在转录报告基因的细胞中持续存在，因此构成了腹侧中胚层谱系的示踪剂。我们利用这一特性表明，wnt8a 表达标志着 Nodal 非依赖性尾部中胚层的形成，并且 Ntl/Bra 主要调节轴旁中胚层祖细胞中的 wnt8a。
