Xenopus Wnt11b is identified as a potential pronephric inducer

Abstract

In this study, we aimed to establish if known wnt signaling molecules could be responsible for inducing early pronephros specification, using a novel and effective in vitro bioassay in Xenopus embryos. Anterior somites have the unique biological activity to signal to unspecified intermediate mesoderm to induce pronephros formation in Xenopus embryos. We have used a molecular candidate gene approach to analyze both canonical and noncanonical wnt expression in isolated anterior and posterior somites and dissected presumptive pronephros, pronephric anlagen, and pronephros from stage 12.5-35 embryos. We have identified potential candidate wnt genes expressed in the right time and place to specify pronephric development. These candidates were then directly tested in an in vitro pronephrogenesis assay based on Holtfreter sandwich cultures. Results revealed that noncanonical wnt11b and wnt11 can induce pronephros formation in vitro. Loss-of-function experiments confirmed that these genes are necessary for normal pronephros development. Developmental Dynamics 239:148 -159, 2010.

Heat Shock 70-kDa Protein 5 (Hspa5) Is Essential for Pronephros Formation by Mediating Retinoic Acid Signaling

“…It is initiated from the intermediate mesoderm at neurula stages. Many signaling pathways including bone morphogenetic protein (7), Wnt (8), FGF (9), Notch (10), and retinoic acid (RA) 5 signaling have been implicated in pronephros development. These coordinated signaling cascades trigger the expression of a series of transcription factors that include Lim homeobox protein 1 (Lhx1), Wt1, and Pax8, which orchestrate the induction of the pronephros primordium.…”

Pronephric Tubulogenesis Requires Daam1-Mediated Planar Cell Polarity Signaling

“…34,38 Multiple signals contribute to nephron formation, including those of the fibroblast growth factor, bone morphogenic protein, and Wnt pathways. 31,39,40 Numerous Wnt ligands are expressed in the developing kidney, including Wnt2, Wnt4, Wnt5a, Wnt6, Wnt7b, Wnt8, Wnt9a, Wnt9b, Wnt11, and Wnt11b, [41][42][43][44][45][46][47][48] and several of these are required for nephrogenesis. Although the downstream signaling trajectories for several of these Wnt ligands have been identified, many within the context of kidney development remain unclear.…”

TRPP2-dependent Ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment inXenopus

“…It is likely that Ca 2+ -signaling-dependent regulation of pax8 takes place downstream of the signals potentially responsible for kidney field specification during gastrulation, such as RA (Cartry et al, 2006) or Wnt11b (Tételin andJones, 2010). In this work we show that a TRPP2-dependent Ca 2+ signaling is not acting upstream of lhx1, osr1 or osr2.…”

“…It is therefore likely that lhx1 or osr1, osr2 and pax8 are differently regulated by the signals potentially responsible for kidney field specification during gastrulation, such as RA (Cartry et al, 2006) andWnt11b (Tételin andJones, 2010). As outlined above, some of these genes are directly regulated by specification signals.…”