Molecular cloning and characterization of WNT3A and WNT14 clustered in human chromosome 1q42 region

Association of single nucleotide polymorphisms in WNT genes with the risk of nonsyndromic cleft lip with or without cleft palate

Nonsyndromic cleft lip with or without cleft palate is a common congenital deformity worldwide with multifaceted etiology. Interaction of genes and environmental factors has been indicated to be related with susceptibility to nonsyndromic cleft lip with or without cleft palate. Some WNT genes which are involved in craniofacial embryogenesis may play a key role in the pathogenesis of nonsyndromic cleft lip with or without cleft palate. In the present study, we aimed to inspect the relationship between WNT3 (rs3809857 and rs9890413), WNT3A (rs752107 and rs3121310), and WNT10a rs201002930 (c.392 C>T) polymorphisms and nonsyndromic cleft lip with or without cleft palate in an Iranian population. The present case-control study was carried out on 120 unrelated nonsyndromic cleft lip with or without cleft palate patients and 112 healthy subjects. The variants were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. The findings suggest that the rs3809857 polymorphism significantly decreased the risk of nonsyndromic cleft lip with or without cleft palate in codominant (odds ratio = 0.16, 95% confidence interval = 0.03-0.75, P = 0.020, TT vs GG), recessive (odds ratio = 0.16, 95% confidence interval = 0.03-0.72, P = 0.009, TT vs GG + GT) inheritance models. The rs9890413 variant marginally decreased the risk of nonsyndromic cleft lip with or without cleft palate in codominant (odds ratio = 0.41, 95% confidence interval = 0.17-0.99, P = 0.047, AG vs AA) model. Regarding C392T variant, the findings revealed that this variant significantly decreased the risk of nonsyndromic cleft lip with or without cleft palate in codominant (odds ratio = 0.24, 95% confidence interval = 0.10-0.58, P = 0.002, CT vs CC) and allele (odds ratio = 0.26, 95% confidence interval = 0.11-0.62, P = 0.002, T vs C) models. No significant association was observed between the rs752107 and rs3121310 variants and risk/protection of nonsyndromic cleft lip with or without cleft palate. Stratified analysis showed that WNT10a rs201002930 (c.392 C>T) significantly decreased the risk of cleft lip with cleft palate and cleft palate only. In summary, the results suggest an association between WNT genes polymorphisms and the risk nonsyndromic cleft lip with or without cleft palate in a sample of the southeast Iranian population.

MicroRNA-29 induces cellular senescence in aging muscle through multiple signaling pathways

The mechanisms underlying the development of aging-induced muscle atrophy are unclear. By microRNA array and individual qPCR analyses, we found significant up-regulation of miR-29 in muscles of aged rodents vs. results in young. With aging, p85α, IGF-1 and B-myb muscle levels were lower while the expression of certain cell arrest proteins (p53, p16 and pRB) increased. When miR-29 was expressed in muscle progenitor cells (MPC), their proliferation was impaired while SA-βgal expression increased signifying the development of senescence. Impaired MPC proliferation resulted from interactions between miR-29 and the 3'-UTR of p85a, IGF-1 and B-myb, suppressing the translation of these mediators of myoblast proliferation. In vivo, electroporation of miR-29 into muscles of young mice suppressed the proliferation and increased levels of cellular arrest proteins, recapitulating aging-induced responses in muscle. A potential stimulus of miR-29 expression is Wnt-3a since we found that exogenous Wnt-3a stimulated miR-29 expression 2.7-fold in primary cultures of MPCs. Thus, aging-induced muscle senescence results from activation of miR-29 by Wnt-3a leading to suppressed expression of several signaling proteins (p85α, IGF-1 and B-myb) that act coordinately to impair the proliferation of MPCs contributing to muscle atrophy. The increase in miR-29 provides a potential mechanism for aging-induced sarcopenia.

Wnt3 gene expression promotes tumor progression in non-small cell lung cancer

The Wnt gene family encodes the multi-functional signaling glycoproteins regulating various normal and pathological processes including tumorigenesis. We investigated the clinical significance of the Wnt3 gene expression in relation to its target genes, c-Myc and survivin, in patients with non-small cell lung cancer (NSCLC). One hundred and twenty-eight patients who underwent resection of NSCLC were analyzed. Quantitative reverse transcription polymerase chain reaction (RT-PCR) was performed to evaluate the gene expression of Wnt3, c-Myc, and survivin. Immunohistochemistry was performed to investigate the protein expression of Wnt3, c-Myc, and survivin. The Ki-67 proliferation index and the apoptotic index using the TUNEL method were also evaluated. Twenty-four carcinomas (18.8%) were found to be high-Wnt3 tumors. The high-Wnt3 tumors were significantly more in squamous cell carcinomas than that in adenocarcinomas (P=0.0022). The Wnt3 gene expression was significantly associated with gene expressions of c-Myc (P=0.0103) and survivin (P=0.0009). As a result, the Ki-67 proliferation index was significantly higher in high-Wnt3 tumors than in low-Wnt3 tumors (P=0.0056). The apoptotic index was significantly lower in high-Wnt3 tumors than in low-Wnt3 tumors (P=0.0245). The overall survival rate was significantly lower in patients with high-Wnt3 tumors than in those with low-Wnt3 tumors (P=0.0020). A Cox regression analysis demonstrated that the Wnt3 status was a significant prognostic factor for NSCLC patients (hazard ratio 2.226, P=0.0296). The present study revealed that Wnt3 gene expression was significantly associated with c-Myc and survivin gene expressions, tumor proliferation, and tumor apoptosis. During the progression of NSCLC, Wnt3 overexpression could be associated with the development of more aggressive tumors.

Conservation, loss, and redeployment of Wnt ligands in protostomes: implications for understanding the evolution of segment formation

Background

The Wnt genes encode secreted glycoprotein ligands that regulate a wide range of developmental processes, including axis elongation and segmentation. There are thirteen subfamilies of Wnt genes in metazoans and this gene diversity appeared early in animal evolution. The loss of Wnt subfamilies appears to be common in insects, but little is known about the Wnt repertoire in other arthropods, and moreover the expression and function of these genes have only been investigated in a few protostomes outside the relatively Wnt-poor model species Drosophila melanogaster and Caenorhabditis elegans. To investigate the evolution of this important gene family more broadly in protostomes, we surveyed the Wnt gene diversity in the crustacean Daphnia pulex, the chelicerates Ixodes scapularis and Achaearanea tepidariorum, the myriapod Glomeris marginata and the annelid Platynereis dumerilii. We also characterised Wnt gene expression in the latter three species, and further investigated expression of these genes in the beetle Tribolium castaneum.

Results

We found that Daphnia and Platynereis both contain twelve Wnt subfamilies demonstrating that the common ancestors of arthropods, ecdysozoans and protostomes possessed all members of all Wnt subfamilies except Wnt3. Furthermore, although there is striking loss of Wnt genes in insects, other arthropods have maintained greater Wnt gene diversity. The expression of many Wnt genes overlap in segmentally reiterated patterns and in the segment addition zone, and while these patterns can be relatively conserved among arthropods and the annelid, there have also been changes in the expression of some Wnt genes in the course of protostome evolution. Nevertheless, our results strongly support the parasegment as the primary segmental unit in arthropods, and suggest further similarities between segmental and parasegmental regulation by Wnt genes in annelids and arthropods respectively.

Conclusions

Despite frequent losses of Wnt gene subfamilies in lineages such as insects, nematodes and leeches, most protostomes have probably maintained much of their ancestral repertoire of twelve Wnt genes. The maintenance of a large set of these ligands could be in part due to their combinatorial activity in various tissues rather than functional redundancy. The activity of such Wnt 'landscapes' as opposed to the function of individual ligands could explain the patterns of conservation and redeployment of these genes in important developmental processes across metazoans. This requires further analysis of the expression and function of these genes in a wider range of taxa.

Wnt14 inhibits death of retinal precursor cells

An earlier proteomics study from our laboratory showed that Wnt14, a member of the Wnt family that regulates the development of vertebrates, was one of the proteins expressed transiently during the development of the chick retina. The purpose of this study was to determine in more detail the changes in the expression of Wnt14 during the development of the chick retina, and to investigate the biological function of Wnt14. Endogenous Wnt14 is located in the retinal ganglion cell layer, and is expressed in the chick retina on embryonic days (ED) 7, ED11, and ED15. The level of Wnt14 is transiently decreased on ED11. In vitro analysis showed that an over-expression of Wnt14 reduced the activation of caspase-3 and inhibited the death of R28 cells induced by serum deprivation or exposure to glutamate. An interferon-induced protein was identified as the protein that was bound to Wnt14. These results suggest that a stable expression of Wnt14 inhibits cell death by inactivating caspase-3 in the developing retina.

Networking of WNT, FGF, Notch, BMP, and Hedgehog signaling pathways during carcinogenesis

The biological functions of some orthologs within the human genome and model-animal genomes are evolutionarily conserved, but those of others are divergent due to protein evolution and promoter evolution. Because WNT signaling molecules play key roles during embryogenesis, tissue regeneration and carcinogenesis, the author's group has carried out a human WNT-ome project for the comprehensive characterization of human genes encoding WNT signaling molecules. From 1996 to 2002, we cloned and characterized WNT2B/WNT13, WNT3, WNT3A, WNT5B, WNT6, WNT7B, WNT8A, WNT8B, WNT9A/WNT14, WNT9B/WNT14B, WNT10A, WNT10B, WNT11, FZD1, FZD2, FZD3, FZD4, FZD5, FZD6, FZD7, FZD8, FZD10, FRAT1, FRAT2, NKD1, NKD2, VANGL1, RHOU/ARHU, RHOV/ARHV, GIPC2, GIPC3, FBXW11/betaTRCP2, SOX17, TCF7L1/TCF3, and established a cDNA-PCR system for snap-shot and dynamic analyses on the WNT-transcriptome. In 2003, we identified and characterized PRICKLE1, PRICKLE2, DACT1/DAPPER1, DACT2/DAPPER2, DAAM2, and BCL9L. After completion of the human WNT-ome project, we have been working on the stem cell signaling network. WNT signals are transduced to beta-catenin, NLK, NFAT, PKC, JNK and RhoA signaling cascades. FGF20, JAG1 and DKK1 are target genes of the WNT-beta-catenin signaling cascade. Cross-talk of WNT and FGF signaling pathways potentiates beta-catenin and NFAT signaling cascades. BMP signals induce IHH upregulation in co-operation with RUNX. Hedgehog signals induce upregulation of SFRP1, JAG2 and FOXL1, and then FOXL1 induces BMP4 upregulation. The balance between WNT-FGF-Notch and BMP-Hedgehog signaling networks is important for the maintenance of homoestasis among stem and progenitor cells. Disruption of the stem cell signaling network results in pathological conditions, such as congenital diseases and cancer.

Human brain endothelial cells (HUBEC) promote SCID repopulating cell expansion through direct contact

The objective of this study was to re-evaluate the previously published hematopoietic stem cell (HSC) expansion work using human brain endothelial cells (HUBEC). The expansion effect of contact and non-contact conditions was reported to be equivalent by others. However, we report here different results that the expansion can be achieved only with direct contact. We co-cultured human CD34+ cells with and without HUBEC contact for seven days with cytokines and the readouts were CD34+ / CD38 - phenotype and SCID repopulating cell (SRC) frequency. Also tested was the inhibitory effect of Wnt receptor inhibitor Dkk-1 on HUBEC contact ex vivo expansion; whether an increased expression of Wnt3 occurs on the HUBEC surface; and detection of an increased nuclear localization of beta-catenin in CD34+ / CD38- cells in HUBEC contact culture condition. We conclude that the successful expansion by HUBEC contact culture is a candidate explanation based on the Wnt family protein, possibly Wnt3, expression on HUBEC.

Complex expression pattern of Wnt ligands and frizzled receptors in human placenta and its trophoblast subtypes

Canonical Wingless (Wnt) signalling provoked by exogenous and endogenous Wnt ligands was recently shown to play a crucial role in the invasive differentiation of human trophoblasts. To gain insights into the expression pattern of the developmental regulators, we analysed all human Wnt ligands and their frizzled (FZD) receptors in the human placenta and different trophoblast model systems using semi-quantitative PCR. Fourteen out of 19 Wnt ligands and 8 out of 10 FZD receptors were detectable in placental tissues, however, expression patterns varied with gestational age and between different trophoblast subtypes suggesting cell-specific functions. Besides Wnt ligands acting through the canonical pathway, non-canonical ligands such as Wnt-5a, which may also activate alternative Wnt signalling pathways or inhibit canonical Wnt signalling, could be identified. Western blot analyses revealed secretion of Wnt-5a from primary trophoblast cultures and trophoblastic cell lines. To evaluate the potential role of Wnt-5a, SGHPL-5 trophoblast cells were transfected with luciferase reporter plasmids harbouring eight T-cell factor (TCF) DNA-recognition sequences which are exclusively activated through the canonical Wnt signalling pathway. Luciferase assays revealed that Wnt-3a-induced reporter activity was repressed by recombinant Wnt-5a indicating an antagonistic role in trophoblasts. The data suggest that a complex network of Wnt ligands and FZD receptors may regulate developmental processes of the human placenta.

Activation of the canonical wingless/T-cell factor signaling pathway promotes invasive differentiation of human trophoblast

The molecular mechanisms governing invasive differentiation of human trophoblasts remain largely elusive. Here, we investigated the role of Wnt-beta-catenin-T-cell factor (TCF) signaling in this process. Reverse transcriptase-polymerase chain reaction and Western blot analyses demonstrated expression of Wnt ligands, frizzled receptors, LRP-6, and TCF-3/4 transcription factors in total placenta and different trophoblast cell models. Immunohistochemistry of placental tissues and differentiating villous explant cultures showed that expression of TCF-3/4 strongly increased in invading trophoblasts. Some of these cells also accumulated dephosphorylated beta-catenin in the nucleus. Wnt3A treatment of primary cytotrophoblasts and SGHPL-5 cells induced activity of TCF-luciferase reporters. Accordingly, the ligand provoked interaction of TCF-3/4 with beta-catenin as assessed in electrophoretic mobility shift assays (EMSAs) and up-regulation of Wnt/TCF target genes as observed by Western blot analyses. Wnt3A stimulated trophoblast migration and invasion through Matrigel, which could be blocked by addition of Dickkopf-1, mediating in-hibition of canonical Wnt signaling. Dickkopf-1 also reduced basal migration, invasion, and proliferation of cytotrophoblasts, suggesting expression of endogenous Wnt ligand(s). Immunohistochemistry revealed that the percentage of extravillous trophoblasts containing nuclear beta-catenin was significantly higher in placentas of complete hydatidiform mole pregnancies as compared to normal placentas. Thus, canonical Wnt signaling may promote invasive trophoblast differentiation, and exaggerated activation of the path-way could contribute to trophoblastic hyperplasia and local invasion.

Glypican-3 promotes the growth of hepatocellular carcinoma by stimulating canonical Wnt signaling

Glypican-3 (GPC3) is a heparan sulfate proteoglycan that is bound to the cell membrane by a glycosyl-phosphatidylinositol anchor. GPC3 is expressed by most hepatocellular carcinomas but not by normal hepatocytes and benign liver lesions. We report here that GPC3 stimulates the in vitro and in vivo growth of hepatocellular carcinoma cells by increasing autocrine/paracrine canonical Wnt signaling. Co-immunoprecipitation experiments showed that GPC3 is able to form complexes with Wnts, and cell-binding assays indicated that GPC3-expressing cells have an increased capacity to bind Wnt. Collectively, these results suggest that GPC3 stimulates Wnt activity by facilitating the interaction of this polypeptide with its signaling receptors. Surprisingly, in contrast to the current model that proposes that Wnt-glypican binding is mediated by the heparan sulfate chains, we found that the nonglycanated GPC3 core protein can form complexes with Wnts. Furthermore, we showed that the glycosaminoglycan chains are not required for the stimulatory effect on Wnt signaling and hepatocellular carcinoma growth.

β-Catenin/T-cell factor-mediated transcription is modulated by cell density in human bronchial epithelial cells

The embryonic Wnt/beta-catenin ('canonical') pathway has been implicated in epithelial regeneration. To investigate the role of Wnt signal transduction in the airways, we characterised the expression of key pathway components in human bronchial epithelial cells (HBEC) and studied the influence of cell density on pathway activity, using sub-confluent cells in log-phase growth as a simple model of repairing epithelium. Primary HBEC and H292 bronchial epithelial cells were found to express TCF-4, TCF-3 and isoforms of LEF-1, transcription factors that are regulated by Wnt signalling. The cells also had the potential to respond to Wnt signalling through expression of several members of the Frizzled receptor family, including FZD-5 and -6. In confluent H292 cells, 20 mM lithium and 25% v/v Wnt-3a conditioned medium induced 4.5-fold (p = 0.008) and 1.4-fold (p = 0.006) increases in TOPflash activity, respectively. Under conditions of reduced cell density, TOPflash activity increased 1.8-fold (p = 0.002) in association with increased nuclear localisation of hypophosphorylated (active) beta-catenin and increased cell proliferation. This up-regulation in reporter activity occurred independently of EGF receptor activation and could not be recapitulated by use of low-calcium medium to disrupt cadherin-mediated cell-cell adhesion, but was associated with changes in FZD-6 expression. We conclude that reactivation of this embryonic pathway may play an important role in bronchial epithelial regeneration, and that modulation of Fzd-6 receptors may regulate Wnt signalling at confluence. Recognising that many chronic inflammatory disorders of the airways involve epithelial damage and repair, altered Wnt signalling might contribute to disease pathogenesis or progression.

Abnormal pigmentation in hypomelanosis of Ito and pigmentary mosaicism: the role of pigmentary genes

There is increasing evidence that hypomelanosis of Ito and related disorders such as linear and whorled naevoid hypermelanosis are due to mosaicism for a variety of chromosomal abnormalities. This group of disorders is better termed 'pigmentary mosaicism'. In this review we explain how disparate chromosomal abnormalities might manifest as a common pigmentary phenotype. In particular, we provide evidence supporting the hypothesis that the chromosomal abnormalities reported in these disorders specifically disrupt expression or function of pigmentary genes.

Congenital and idiopathic scoliosis: clinical and genetic aspects

OBJECTIVE

Genetic and environmental factors influencing spinal development in lower vertebrates are likely to play a role in the abnormalities associated with human congenital scoliosis (CS) and idiopathic scoliosis (IS). An overview of the molecular embryology of spinal development and the clinical and genetic aspects of CS and IS are presented. Utilizing synteny analysis of the mouse and human genetic databases, likely candidate genes for human CS and IS were identified.

DESIGN

Review and synteny analysis.

METHODS

A search of the Mouse Genome Database was performed for "genes," "markers" and "phenotypes" in the categories Neurological and neuromuscular, Skeleton, and Tail and other appendages. The Online Mendelian Inheritance in Man was used to determine whether each mouse locus had a known human homologue. If so, the human homologue was assigned candidate gene status. Linkage maps of the chromosomes carrying loci with possibly relevant phenotypes, but without known human homologues, were examined and regions of documented synteny between the mouse and human genomes were identified.

RESULTS

Searching the Mouse Genome Database by phenotypic category yielded 100 mutants of which 66 had been mapped. The descriptions of each of these 66 loci were retrieved to determine which among these included phenotypes of scoliosis, kinky or bent tails, other vertebral abnormalities, or disturbances of axial skeletal development. Forty-five loci of interest remained, and for 27 of these the comparative linkage maps of mouse and human were used to identify human syntenic regions to which plausible candidate genes had been mapped.

CONCLUSION

Synteny analysis of mouse candidate genes for CS and IS holds promise due to the close evolutionary relationship between mice and human beings. With the identification of additional genes in animal model systems that contribute to different stages of spine development, the list of candidate genes for CS and IS will continue to grow.

Mouse Wnt9b transforming activity, tissue-specific expression, and evolution

The members of the Wnt family of secreted factors have oncogenic potential and important roles as developmental regulators. We report an analysis of mouse Wnt9b (also called Wnt15 and Wnt14b), including its cDNA sequence, chromosomal mapping, epithelial cell transforming activity, adult and embryonic tissue expression patterns, and evolution. We also deduced the full-length amino acid sequence of its close relative, Wnt9a (also called Wnt14), from unannotated genomic DNA sequences in GenBank. Full-length comparisons among Wnt amino acid sequences provide evidence that Wnt9b and Wnt9a are close paralogs of each other and are orthologs of Wnt9 genes from shark and hagfish. Mapping Wnt9b to The Jackson Laboratory BSS interspecific backcross panel places it at 63.0 cM on chromosome 11. Sequence comparisons of two pairs of linked Wnt genes (the Wnt9a-Wnt3a pair and the Wnt9b-Wnt3 pair) suggest that they arose from the relatively recent duplication of a single ancestral Wnt gene pair, confirming the close paralogous relationship of Wnt9a and Wnt9b. Wnt9b expression is primarily restricted to the kidney in the adult mouse, with lower levels detected in the preputial gland, liver, and mammary gland. Testing of staged whole mouse embryos from 9.5 to 17.5 days of gestation showed expression at all stages with a peak at day 10.5. In situ hybridization analysis showed expression in most but not all tissues of the 16.5-day embryo. No significant elevation of Wnt9b expression was detected in 29 mouse mammary tumor virus-induced tumors. Overexpression of Wnt9b in C57MG mammary epithelial cells caused small transformed foci in cell monolayers and a moderate morphological transformation in pooled colonies compared with Wnt1.

The Wnts

SUMMARY

The Wnt genes encode a large family of secreted protein growth factors that have been identified in animals from hydra to humans. In humans, 19 WNT proteins have been identified that share 27% to 83% amino-acid sequence identity and a conserved pattern of 23 or 24 cysteine residues. Wnt genes are highly conserved between vertebrate species sharing overall sequence identity and gene structure, and are slightly less conserved between vertebrates and invertebrates. During development, Wnts have diverse roles in governing cell fate, proliferation, migration, polarity, and death. In adults, Wnts function in homeostasis, and inappropriate activation of the Wnt pathway is implicated in a variety of cancers.

WNT2B2 mRNA, up-regulated in primary gastric cancer, is a positive regulator of the WNT- beta-catenin-TCF signaling pathway

Genetic alterations of WNT signaling molecules lead to carcinogenesis through activation of the beta-catenin-TCF signaling pathway. We have previously cloned and characterized WNT2B/WNT13 gene on human chromosome 1p13, which is homologous to proto-oncogene WNT2 on human chromosome 7q31. WNT2B1 and WNT2B2 mRNAs, generated from the WNT2B gene due to alternative splicing of the alternative promoter type, encode almost identical polypeptides with divergence in the N-terminal region. WNT2B2 mRNA rather than WNT2B1 mRNA is preferentially expressed in NT2 cells with the potential of neuronal differentiation. Here, we describe our investigations of expression of WNT2B mRNAs in various types of human primary cancer. Matched tumor/normal expression array analysis revealed that WNT2B mRNAs were significantly up-regulated in 2 of 8 cases of primary gastric cancer. WNT2B2 mRNA rather than WNT2B1 mRNA was found to be preferentially up-regulated in a case of primary gastric cancer (signet ring cell carcinoma). Function of WNT2B1 mRNA and that of WNT2B2 mRNA were investigated by using Xenopus axis duplication assay. Injection of synthetic WNT2B1 mRNA into the ventral marginal zone of fertilized Xenopus eggs at the 4-cell stage did not induce axis duplication. In contrast, ventral injection of synthetic WNT2B2 mRNA induced axis duplication in 90% of embryos (complete axis duplication, 24%). These results strongly suggest that WNT2B2 up-regulation in some cases of gastric cancer might lead to carcinogenesis through activation of the beta-catenin-TCF signaling pathway.