<i>Xwnt-8</i>, a <i>Xenopus Wnt</i>-1/<i>int</i>-1-related gene responsive to mesoderminducing growth factors, may play a role in ventral mesodermal patterning during embryogenesis

TLDR

In amphibian embryos, body plan formation relies on positional differences in the mesoderm, and although peptide growth factors involved in mesoderm induction have been tentatively identified, additional signals are required to generate patterning in this tissue. We isolated the Xenopus Wnt‑1 related gene Xwnt‑8, found it transiently expressed during gastrulation in ventral mesoderm, downregulated by lithium, and that ectopic expression induces a dorsoanterior phenotype, indicating that Xwnt‑8 acts as a secondary signaling agent in early mesodermal patterning.

Abstract

ABSTRACT In amphibian embryos, formation of the basic body plan depends on positional differences in the mesoderm. Although peptide growth factors involved in mesoderm induction have tentatively been identified, additional signals are required to generate pattern in this tissue. We have isolated a Xenopus cDNA for a Wnt-1 related gene, designated Xwnt-8, which is activated in ‘response to mesoderm-inducing growth factors. Xwnt-8 transcripts are transiently expressed, being most abundant during gastrulation at which time expression is confined primarily to ventral mesodermal cells. Embryos dor-soanteriórized by exposure to lithium exhibit greatly reduced levels of Xwnt-8 mRNA, supporting a correlation between Xwnt-8 expression and a ventral mesodermal cell fate. Surprisingly, ectopic expression of Xwnt-8 in embryos causes a dorsoanterior-enhanced phenotype. These findings suggest that Awni-S may be a secondary signalling agent which is produced in response to mesoderm-inducing factors and is involved in the early steps of mesodermal patterning.