Ancestral Regulatory Circuits Governing Ectoderm Patterning Downstream of Nodal and BMP2/4 Revealed by Gene Regulatory Network Analysis in an Echinoderm
Figure 8
Epistasis analysis of dorsal genes: irxA as a repressor of ciliary band gene expression downstream of tbx2/3.
(A) tbx2/3 morphants are partially radialized and do not elongate along the D/V axis. The expression of ventral genes such as chordin, foxA, brachyury, onecut/hnf6 and of ciliary band genes such as pax2/5/8 and fgfA is largely normal in these embryos. In contrast, expression of dorsal marker genes such as msx, dlx, irxA and atbf1 is lost at gastrula stages. (B) irxA morphants are partially radialized and occasionally show an ectopic ciliary band like thickened region within the dorsal region. Expression of onecut/hnf6 is dramatically expanded towards the dorsal side of irxA morphants. (C) Onecut/hnf6 morphants are slightly radialized but do form a morphologically recognizable ciliary band. In these embryos, the expression of ciliary band genes gfi1 is absent while the expression of pax2/5/8, foxG or deadringer is strongly reduced. lv, lateral view, vv, vegetal pole view, av, animal pole view, dv, dorsal view, fv, frontal view.