Analysis of the niche for mouse germ cell specification

在小鼠体内，原始生殖细胞(PGCs)的形成受BMP4和WNT3活性的影响。缺乏Dullard活性的胚胎不能形成原生殖细胞。我们发现Dullard的突变对BMP4没有可检测到的影响。遗传学研究结果表明，缺失Dullard对Bmp4和Smads的表达没有明显影响，也不影响BMP4对PGC形成的剂量依赖性诱导活性。相反，Dullard作为一种激动剂，调节WNT信号活动，促进PGC前体的形成。伴随着Dullard功能丧失的是WNT/β-catenin信号活性的下调和Dvl2水平的降低。因此，Dullard可能在WNT信号活性的微调中发挥作用，这对生殖细胞谱系的确定至关重要。

In the mouse, the formation of primordial germ cells (PGCs) is influenced by BMP4 and WNT3 activity. Embryos lacking Dullard activity fail to form PGCs. We found mutations in Dullard had no detectable effect on BMP4. Results of the genetic study showed that loss of Dullard has no discernible effect on the expression of Bmp4 and Smads, and does not affect the dose-dependent inductive activity of BMP4 on PGC formation. Instead, Dullard functions as an agonist that modulates WNT signalling activity to facilitate the formation of PGC precursors. Loss of Dullard function was accompanied by down-regulation of WNT/beta-catenin signalling activity and a reduction in the level of Dishevelled 2 (Dvl2). Therefore, Dullard may play a role in the fine-tuning of WNT signaling activity, which is crucial for the specification of the germ cell lineage.