全周 (9AM - 6PM)

我们和你在一起

Extra info thumb
WNT LIGAND SECRETION MEDIATOR; WLS

WNT LIGAND SECRETION MEDIATOR; WLS

Alternative titles; symbolsWNTLESS, DROSOPHILA, HOMOLOG OFG PROTEIN-COUPLED RECEPTOR 177; GPR177EVENNESS INTERRUPTED, DROSOPHILA, HOMOLOG OF; EVIHGNC Approved Ge...

Alternative titles; symbols

  • WNTLESS, DROSOPHILA, HOMOLOG OF
  • G PROTEIN-COUPLED RECEPTOR 177; GPR177
  • EVENNESS INTERRUPTED, DROSOPHILA, HOMOLOG OF; EVI

HGNC Approved Gene Symbol: WLS

Cytogenetic location: 1p31.3 Genomic coordinates (GRCh38): 1:68,098,458-68,233,017 (from NCBI)

▼ Description
Secreted Wnt (see WNT1, 164820) glycoproteins mediate many developmental processes during embryogenesis, including anterior-posterior axis formation, cell polarity, and cell migration. In adult organs, Wnt proteins maintain stem cell populations. WLS is an evolutionarily conserved transmembrane protein necessary for Wnt protein secretion (summary by Jin et al., 2010).

▼ Cloning and Expression
By searching for homologs of Drosophila Wls, Banziger et al. (2006) identified human GPR177, which they called WLS. The deduced 543-amino acid protein contains an N-terminal signal sequence and 7 transmembrane domains.

Jin et al. (2010) found that human GPR177 is 96% identical to the mouse Gpr177 protein and 78% identical to the zebrafish protein. They identified 2 potential sites for N-glycosylation in human GPR177. Western blot analysis detected Gpr177 in all mouse and rat tissues examined and in all brain regions examined. In mouse and rat cerebellum, Gpr177 localized predominantly within Purkinje cells. In zebrafish, Gpr177 was expressed throughout embryogenesis and was detectable as early as 1 hour postfertilization. In situ hybridization revealed prominent Gpr177 expression in brain and ear of embryonic zebrafish. Epitope-tagged human GRP177 was expressed at the plasma membrane and in a punctate cytoplasmic distribution in transfected HEK293 cells. Western blot analysis detected endogenous GPR177 at an apparent molecular mass of about 46 kD in HEK293 and SH-SY5Y cells, and glycosidase treatment reduced the apparent molecular mass of the protein.

▼ Mapping
Hartz (2013) mapped the WLS gene to chromosome 1p31.3 based on an alignment of the WLS sequence (GenBank AK026744) with the genomic sequence (GRCh37).

▼ Gene Function
Using small interfering RNA directed against WLS in human embryonic kidney (HEK293) cells expressing a WNT3A (606359) reporter plasmid, Banziger et al. (2006) demonstrated that WLS was required for cell surface WNT3A expression. They concluded that WLS plays an essential role in WNT-mediated cell-cell communication in human cells, in agreement with results obtained in Drosophila and C. elegans.

Bartscherer et al. (2006) found that WLS was required for WNT signaling in HEK293 cells. Fluorescence-tagged WLS was expressed at the cell surface.

Jin et al. (2010) found that HEK293 cells expressing epitope-tagged GPR177 supported secretion of cotransfected WNT3.

Stefater et al. (2011) showed that during development, retinal myeloid cells produce Wnt ligands to regulate blood vessel branching. In the mouse retina, where angiogenesis occurs postnatally, somatic deletion in retinal myeloid cells of the Wnt ligand transporter Wntless results in increased angiogenesis in the deeper layers. Stefater et al. (2011) also showed that mutation of Wnt5a (164975) and Wnt11 (603699) results in increased angiogenesis and that these ligands elicit retinal myeloid cell responses via a noncanonical Wnt pathway. Using cultured myeloid-like cells and retinal myeloid cell somatic deletion of Flt1 (165070), Stefater et al. (2011) showed that Flt1, a naturally occurring inhibitor of VEGF (192240), is an effector of Wnt-dependent suppression of angiogenesis by retinal myeloid cells. Stefater et al. (2011) concluded that resident myeloid cells can use a noncanonical, Wnt-Flt1 pathway to suppress angiogenic branching.

By coimmunoprecipitation analysis of transfected HEK293 cells, Zhu et al. (2013) found that mouse Gpr177 interacted with every Wnt ligand tested. Overexpression of Gpr177 enhanced Wnt secretion to the media.

▼ Molecular Genetics
In 10 affected individuals from 5 unrelated families with Zaki syndrome (ZKS; 619648) who had delayed global milestones, short stature, progressive microcephaly, and variable dysmorphic features and other anomalies, Chai et al. (2021) identified homozygosity for missense mutations in the WLS gene (611514.0001-611514.0004). The mutations segregated fully with disease in the respective families, and functional analysis demonstrated a significant reduction in Wnt signaling with all of the variants.

▼ Animal Model
Banziger et al. (2006) and Bartscherer et al. (2006) found that Wls was required for proper wingless (see 164820) pathway activity at multiple stages of fly development.

Zhu et al. (2013) found that targeted deletion of Gpr177 in epithelium of mice resulted in perinatal lethality. Examination of embryonic teeth revealed that deletion of Gpr177 led to arrest of tooth development at the early cap stage and abrogated tooth-forming ability of the dental epithelium. In culture, mutant dental epithelium lacked Wnt secretion and canonical Wnt signaling activity. Deletion of Axin2 (604025), an inhibitor of canonical Wnt signaling, rescued the tooth defects in mutant embryos.

Augustin et al. (2013) generated mice with conditional knockout of Wls in epidermis and observed hair loss during the first hair cycle, showing reddish skin with impaired skin barrier function. Expression profiling revealed upregulation of inflammation-associated genes. Immunohistochemical and flow cytometric analyses demonstrated that Wls mutant skin, in an age-dependent manner, had significantly fewer dendritic epidermal T cells and high levels of Tcr-positive gamma/delta cells. Epidermal loss of Wls also promoted growth of cutaneous blood vessels and keratinocytes. Study of human psoriatic skin biopsies showed downregulation of WLS expression. Augustin et al. (2013) concluded that the inflammatory skin phenotype in Wls-deficient mice indicates an essential role for Wnt secretion in maintaining normal skin homeostasis by enabling balanced epidermal-dermal communication.

Chai et al. (2021) generated knock-in mice carrying the Wls Y392C (611514.0001) or Y478C (611514.0002) mutations. Heterozygotes were healthy and viable, but homozygous mutants showed perinatal lethality. Nearly all mutants in both lines had defects in caudal neural tube closure, with severely reduced or absent tail buds and reduced numbers of caudal vertebrae. Cystic medullary hydronephrosis was observed in both lines, as well as reduced numbers of forelimb and hindlimb digits. Mutants in both lines also showed a notably reduced brain size, with severely defective hippocampal dentate gyrus, decreased numbers of cortical neurons, and cobblestone-like penetration of neurons through the disrupted pial basement membrane. The authors noted that the findings in the knock-in mice recapitulated the major defects observed in patients with Zaki syndrome (see MOLECULAR GENETICS). Intraperitoneal administration of a pharmacologic Wnt agonist during embryogenesis resulted in partial rescue of the phenotype, including increased tail length and number of caudal vertebrae, reduction in incidence of hydronephrosis, and increase in brain size.

▼ ALLELIC VARIANTS ( 4 Selected Examples):

.0001 ZAKI SYNDROME
WLS, TYR392CYS
In 5 affected sibs from a consanguineous family from the United Arab Emirates (family 1) with Zaki syndrome (ZKS; 619648), Chai et al. (2021) identified homozygosity for a c.1175A-G transition in exon 9 of the WLS gene, resulting in a tyr392-to-cys (Y392C) substitution at a highly conserved residue within the sixth transmembrane domain. Their unaffected first-cousin parents were heterozygous for the mutation, which was not found in the gnomAD database. Expression analysis in transfected HEK293T cells and in cultures of embryonic fibroblasts from mice with homozygous knock-in of the Y392C mutation demonstrated reduction by 40 to 50% of mutant protein levels compared to wildtype WLS. Transfected HEK293T cells showed intracellular levels of WNT3A (606359) and WNT5A (164975) that were similar in cells carrying mutated or wildtype WLS; however, levels of secreted WNT3A and WNT5A were reduced by approximately 80% in cells carrying the Y392C mutant compared to wildtype, and the reduction was confirmed in patient and mouse embryonic fibroblasts. Similarly, the authors observed a 50 to 60% reduction in Wnt-reporter luciferase signaling in cells adjacent to cells expressing the Y392C mutant.

.0002 ZAKI SYNDROME
WLS, TYR478CYS
In 2 Egyptian sisters born of first-cousin parents (family 2) and a 5-year-old Native American girl (family 3) with Zaki syndrome (ZKS; 619648), Chai et al. (2021) identified homozygosity for a c.1427A-G transition in exon 11 of the WLS gene, resulting in a tyr478-to-cys (Y478C) substitution at a highly conserved residue within the eighth transmembrane domain. The unaffected parents in both families were heterozygous for the mutation, as was an unaffected brother in the Egyptian family. The mutation fell within regions of homozygosity in the Native American family, suggesting distant consanguinity. Western blot of cultured primary dermal fibroblasts from the Native American girl showed that levels of the mutant protein were 90% lower than those of wildtype WLS in cells from an unrelated healthy control. Expression analysis in transfected HEK293T cells and in cultures of embryonic fibroblasts from mice with homozygous knock-in of the Y478C mutation confirmed reduction by 40 to 50% of mutant protein levels compared to wildtype WLS. Transfected HEK293T cells showed intracellular levels of WNT3A (606359) and WNT5A (164975) that were similar in cells carrying mutated or wildtype WLS; however, levels of secreted WNT3A and WNT5A were reduced by approximately 70% in cells carrying the Y478C mutant compared to wildtype, and the reduction was confirmed in patient and mouse embryonic fibroblasts. Similarly, the authors observed a 50 to 60% reduction in Wnt-reporter luciferase signaling in cells adjacent to cells expressing the Y478C mutant. In a mouse line with green fluorescent protein indicating Wnt activity, Y478C homozygotes showed globally reduced Wnt reporter activity, most notably in facial structures, heart, spinal region, tail bud, metanephros, and neural tissues, which the authors noted were many of the same tissues affected in patients. Embryoid bodies generated from induced pluripotent stem cells from the Native American girl were healthy but 50% smaller than those generated from controls; the addition of a Wnt agonist to the culture rescued the size of the mutant embryoid bodies, suggesting at least partial restoration of Wnt-mediated effects.

.0003 ZAKI SYNDROME
WLS, ILE531THR
In a 9-year-old Brazilian girl (family 4) with Zaki syndrome (ZKS; 619648), Chai et al. (2021) identified homozygosity for a c.1592T-C transition in exon 12 of the WLS gene, resulting in an ile531-to-thr (I531T) substitution at a conserved residue within the fourth intracellular loop, adjacent to the endoplasmic reticulum-targeting signal motif. Her unaffected parents were heterozygous for the mutation, which fell within regions of homozygosity, suggesting distant consanguinity. Transfected HEK293T cells showed intracellular levels of WNT3A (606359) and WNT5A (164975) that were similar in cells carrying mutated or wildtype WLS; however, levels of secreted WNT3A and WNT5A were reduced by approximately 60% in cells carrying the I531T mutant compared to wildtype, and the reduction was confirmed in patient and mouse embryonic fibroblasts. Similarly, the authors observed a 50 to 60% reduction in Wnt-reporter luciferase signaling in cells adjacent to cells expressing the I531T mutant.

.0004 ZAKI SYNDROME
WLS, ARG536CYS
In a 3-year-old Indian girl (family 5) with Zaki syndrome (ZKS; 619648), Chai et al. (2021) identified homozygosity for a c.1606C-T transition in exon 12 of the WLS gene, resulting in an arg536-to-cys (R536C) substitution at a conserved residue within the endoplasmic reticulum-targeting signal motif. Her first-cousin parents were heterozygous for the mutation. Transfected HEK293T cells showed intracellular levels of WNT3A (606359) and WNT5A (164975) that were similar in cells carrying mutated or wildtype WLS; however, levels of secreted WNT3A and WNT5A were reduced by approximately 60% in cells carrying the R536C mutant compared to wildtype, and the reduction was confirmed in patient and mouse embryonic fibroblasts. Similarly, the authors observed a 50 to 60% reduction in Wnt-reporter luciferase signaling in cells adjacent to cells expressing the R536C mutant.

Tags: 1p31.3