A direct role for Wnt8 in ventrolateral mesoderm patterning.

Vertebrate dorsoventral patterning requires both Wnt8 and BMP signaling. Because of their multiple interactions, discerning roles attributable specifically to Wnt8 independent of BMP has been a challenge. For example, Wnt8 represses the dorsal organizer that negatively regulates ventral BMP signals, thus Wnt8 loss-of-function phenotypes may reflect the combined effects of reduced Wnt8 and BMP signaling.

WNT8 and BMP2B co-regulate non-axial mesoderm patterning during zebrafish gastrulation.

During vertebrate mesoderm formation, fates are established according to position in the dorsoventral (D/V) axis of the embryo. Initially, maternal signaling divides nascent mesoderm into axial (dorsal) and non-axial (ventral) domains. Although the subsequent subdivision of non-axial mesoderm into multiple D/V fate domains is known to involve zygotic Wnt8 and BMP signaling as well as the Vent/Vox/Ved family of transcriptional repressors, how levels of signaling activity are translated into differential regulation of fates is not well understood.