The role of Ppt/Wnt5 in regulating cell shape and movement during zebrafish gastrulation

Abstract

Wnt genes play important roles in regulating patterning and morphogenesis during vertebrate gastrulation. In zebrafish, slb/wnt11 is required for convergence and extension movements, but not cell fate specification during gastrulation. To determine if other Wnt genes functionally interact with slb/wnt11, we analysed the role of ppt/wnt5 during zebrafish gastrulation. ppt/wnt5 is maternally provided and zygotically expressed at all stages during gastrulation. The analysis of ppt mutant embryos reveals that Ppt/Wnt5 regulates cell elongation and convergent extension movements in posterior regions of the gastrula, while its function in more anterior regions is largely redundant to that of Slb/Wnt11. Frizzled-2 functions downstream of ppt/wnt5, indicating that it might act as a receptor for Ppt/Wnt5 in this process. The characterisation of the role of Ppt/Wnt5 provides insight into the functional diversity of Wnt genes in regulating vertebrate gastrulation movements.

Wnt5a uses CD146 as a receptor to regulate cell motility and convergent extension

“…The phenotype of CD146 morphant embryos is similar to that of Wnt5a morphants with wider and shorter notochord accompanying a wider and disordered somites (Fig. 5a,b) 36 . These phenotypes commonly result from impaired Wnt/PCP signalling in association with gastrulation defects 35 .…”

Wnt Signaling in Vertebrate Axis Specification

“…Because maternal Wnt11 RNA is vegetally localized (Ku and Melton 1993), one possibility is that Wnt11 is delivered to its future site of action by the cortical rotation (Tao et al 2005). So far, dorsoventral patterning defects have not been described in embryos with genetically reduced Wnt5a or Wnt11 function (Rauch et al 1997;Yamaguchi et al 1999;Heisenberg et al 2000;Kilian et al 2003;Majumdar et al 2003 Fossat et al 2011). Potentially, these observations could be explained by functional redundancy or by the presence of maternally encoded proteins.…”

Wnt5a Signaling Induces Proliferation and Survival of Endothelial Cells In Vitro and Expression of MMP-1 and Tie-2

“…Wnt5a has been shown to function in noncanonical Wnt signaling in several systems. For example, expression of Wnt5a in zebra fish or Xenopus embryos can stimulate intracellular Ca 2ϩ fluxes (Slusarski et al, 1997), and Wnt5a regulates morphogenetic movements during gastrulation independently of canonical signaling (Kilian et al, 2003). Consistent with noncanonical signaling, ectopic overexpression of Wnt5a in human primary endothelial cells did not stabilize cytosolic ␤-catenin or activate ␤-catenin/ TCF-mediated transcription (Wright et al, 1999;Masckauchan et al, 2005).…”