Census of vertebrate Wnt genes: Isolation and developmental expression of Xenopus Wnt2, Wnt3, Wnt9a, Wnt9b, Wnt10a, and Wnt16

Abstract

The Wnt family of growth factors regulate many different aspects of embryonic development. Assembly of the complete mouse and human genome sequences, plus expressed sequence tag surveys have established the existence of 19 Wnt genes in mammalian genomes. However, despite the importance of model vertebrates for studies in developmental biology, the complete complement of Wnt genes has not been established for nonmammalian genomes. Using genome sequences for chicken (Gallus gallus), frog (Xenopus tropicalis), and fish (Danio rerio and Tetraodon nigroviridis), we have analyzed gene synteny to identify the orthologues of all 19 human Wnt genes in these species. We find that, in addition to the 19 Wnts observed in humans, chicken contained an additional Wnt gene, Wnt11b, which is orthologous to frog and zebrafish Wnt11 (silberblick). Frog and fish genomes contained orthologues of the 19 mammalian Wnt genes, plus Wnt11b and several duplicated Wnt genes. Specifically, the Xenopus tropicalis genome contained 24 Wnt genes, including additional copies of Wnt7-related genes (Wnt7c) and 3 recent Wnt duplications (Wnt3, Wnt9b, and Wnt11). The Danio rerio genome contained 27 Wnt genes with additional copies of Wnt2, Wnt2b, Wnt4b, Wnt6, Wnt7a, and Wnt8a. The presence of the additional Wnt11 sequence (Wnt11b) in the genomes of all ancestral vertebrates suggests that this gene has been lost during mammalian evolution. Through these studies, we identified the frog orthologues of the previously uncharacterized Wnt2, Wnt3, Wnt9a, Wnt9b, Wnt10a, and Wnt16 genes and their expression has been characterized during early Xenopus development.

Variability in dentofacial phenotypes in four families with WNT10A mutations

“…WNT genes are involved in hair-follicle morphogenesis, 27,28 skin and tooth embryogenesis [29][30][31] and several other developmental processes. 32 It also explains that in addition to TA, hypoplastic morphological dental features, including conical tooth shapes and microdontia, occur in the permanent teeth which did develop.…”

Evolutionary Dynamics of the wnt Gene Family: A Lophotrochozoan Perspective

“…In light of the genetic linkage between several wnt genes in other metazoans (Garriock et al 2007;Bolognesi et al 2008;Putnam et al 2008), we also looked for scaffolds containing multiple wnt genes in the three lophotrochozoan species ( fig. 2).…”

“…Wnt ligands are secreted glycoproteins 350-400 amino acids in length, whose domain structure is defined by the presence of 23-24 cysteines positioned at conserved sites throughout the protein's length (Nusse and Varmus 1992;Cadigan and Nusse 1997). Comparisons of available whole-genome sequences indicate that 13 wnt subfamilies were present in the common ancestor of cnidarians and bilaterally symmetric animals (Kusserow et al 2005;Croce et al 2006;Garriock et al 2007;Bolognesi et al 2008;Lengfeld et al 2009). Of these, 12 have been retained in Nematostella vectensis, a modern cnidarian, which shows one case of gene duplication, resulting in a total of 12 wnt genes (Kusserow et al 2005; note that originally two gene duplications were reported, however, our close examination indicates that wnt7a and wnt7b are splice variants of a single gene).…”

“…Of these, 12 have been retained in Nematostella vectensis, a modern cnidarian, which shows one case of gene duplication, resulting in a total of 12 wnt genes (Kusserow et al 2005; note that originally two gene duplications were reported, however, our close examination indicates that wnt7a and wnt7b are splice variants of a single gene). The human genome (super-phylum Deuterostomia) contains 19 wnt genes, representing 12 subfamilies with seven duplications (Garriock et al 2007). In contrast, the beetle Tribolium (super-phylum Ecdysozoa) retains only 9 subfamilies, with no duplications (Bolognesi et al 2008), and two other ecdysozoans, Drosophila and Caenorhabditis, have just seven and five wnt genes, respectively (Eisenmann 2005;Bolognesi et al 2008).…”

Modulating expression level of secreted Wnt3 influences cerebellum development in zebrafish transgenics

“…Cerebellar vermis hypoplasia in Joubert syndrome, for example, is linked to defective canonical Wnt signaling (Lancaster et al, 2011). Wnt3 is expressed in the developing cerebellum and the dorsal spinal cord of all vertebrates (Roelink and Nusse, 1991;Bulfone et al, 1993;Garriock et al, 2007;Clements et al, 2009;Anne et al, 2013). In mice, Wnt3 is expressed prior to gastrulation and its targeted deletion causes an early developmental arrest (Liu et al, 1999).…”