Wingless Research Articles

Evaluation of the Effect of Probiotic Administration on Gene Expression in Goat Blood

The objective of this study was to assess the molecular impact of probiotic administration on genes involved in homeostasis and immunity in goat blood. Following initial screening for infection, one-week post weaning, female SpanishXBoer goats were drenched daily with the recommended doses of FASTtrak microbial pack (Conklin Company Inc., Shakopee, MN) in 10 mL sterile water over an 8-week period. The control group were given sterile water. Blood samples were collected weekly. Total RNA was isolated from blood collected at the beginning of the study (week 0) and at the end of the study (week 8) using Tri-reagent and then reverse-transcribed to cDNA using the Ambion-Retroscript kit. Quantification of genes was performed in the CFX96TM Biorad Real-Time PCR detection system with the addition of the dye SYBR green. The cow Wingless (Wnt) signaling pathway, Human Innate & Adaptive Immune Responses and the Cow Inflammatory Cytokine & Receptors RT² Profiler™ PCR Arrays (QIAGEN, Valencia, CA) were used to profile the expression of 84 genes involved in each pathway. Probiotic treatment had no effect on body weight, body condition, fecal egg count and RNA concentration (p>0.05). Packed cell volume and FAMACHA scores were significantly improved by probiotic administration. Results from RT-PCR showed increased expression of genes in innate and adaptive immune response, cytokine and Wnt pathways in response to probiotics. Probiotics induced the expression of 32 genes involved in innate and adaptive immune response inflammatory cytokines, and 48 genes involved in the Wnt signaling pathway. This study provides evidence for a systematic effect of oral probiotic administration on expression of genes involved in immunity and homeostasis in goat blood.

Matricellular proteins in cancer: a focus on secreted Frizzled-related proteins.

Tumours are complex entities, wherein cancer cells interact with myriad soluble, insoluble and cell associated factors. These microenvironmental mediators regulate tumour growth, progression and metastasis, and are produced by cancer cells and by stromal components such as fibroblast, adipocytes and immune cells. Through their ability to bind to extracellular matrix proteins, cell surface receptors and growth factors, matricellular proteins enable a dynamic reciprocity between cancer cells and their microenvironment. Hence, matricellular proteins play a critical role in tumour progression by regulating where and when cancer cells are exposed to key growth factors and regulatory proteins. Recent studies suggest that, in addition to altering Wingless (Wnt) signalling, certain members of the Secreted Frizzled Related Protein (sFRP) family are matricellular in nature. In this review, we outline the importance of matricellular proteins in cancer, and discuss how sFRPs may function to both inhibit and promote cancer progression in a context-dependent manner. By considering the matricellular functionality of sFRPs, we may better understand their apparently paradoxical roles in cancers.

Spatio-temporal kinetics of wingless trafficking and signalling in Drosophila wing imaginal discs

Spatio-temporal kinetics of wingless trafficking and signalling in Drosophila wing imaginal discs

Interrelationships and diversification of ArgynnisFabricius and SpeyeriaScudder butterflies

AbstractDiverse radiations of insects are often associated with adaptations to host plants, and well‐resolved phylogenetic relationships are required to fully understand them. Palearctic Argynnis and related subgenera, together with North American Speyeria butterflies make up a radiation whose species hypotheses are confounded by shared wing colour patterns between sympatric populations of closely related recognized species. Previous studies of this group indicate that Speyeria is a lineage within Argynnis, but sampling in these studies has either involved too few Speyeria species or incomplete sampling of Argynnis species. Thus, no comprehensive phylogenetic analysis exists for all members that answers the question of monophyly of Speyeria, or other subgeneric taxa, and their relationship to Argynnis species. We completed a phylogenetic analysis of all North American Speyeria species and all but one species within Argynnis, using one mitochondrial (cytochrome c oxidase I, COI) and four nuclear genes [elongation factor 1 alpha (EF1α), wingless (WG), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), and ribosomal protein S5 (RPS5)]. The results indicate three major lineages within Argynnis s.l.: two Palearctic and one containing both Palearctic and Nearctic species. In summary, the phylogenetic analyses suggest the need for reorganization into three natural groups: Argynnis, Fabriciana and Speyeria. Within each of these genera the phylogenetic hypothesis indicates an evolutionary history marked by rapid diversification and potential extinction, followed by ongoing lineage sorting. The position of North American Speyeria is nested within the Palearctic lineages, which indicates that the radiation began in Asia and was fuelled by existing Viola diversity in North America. Dating analyses of Viola and Speyeria corroborate this hypothesis. The current North American Speyeria species are mixed on the tree, indicating a recent and ongoing radiation. These results provide needed clarity on the evolution of this group, which contains species of conservation concern.

Adult Muscle Formation Requires Drosophila Moleskin for Proliferation of Wing Disc-Associated Muscle Precursors

Adult muscle precursor (AMP) cells located in the notum of the larval wing disc undergo rapid amplification and eventual fusion to generate the Drosophila melanogaster indirect flight muscles (IFMs). Here we find that loss of Moleskin (Msk) function in these wing disc-associated myoblasts reduces the overall AMP pool size, resulting in the absence of IFM formation. This myoblast loss is due to a decrease in the AMP proliferative capacity and is independent of cell death. In contrast, disruption of Msk during pupal myoblast proliferation does not alter the AMP number, suggesting that Msk is specifically required for larval AMP proliferation. It has been previously shown that Wingless (Wg) signaling maintains expression of the Vestigial (Vg) transcription factor in proliferating myoblasts. However, other factors that influence Wg-mediated myoblast proliferation are largely unknown. Here we examine the interactions between Msk and the Wg pathway in regulation of the AMP pool size. We find that a myoblast-specific reduction of Msk results in the absence of Vg expression and a complete loss of the Wg pathway readout β-catenin/Armadillo (Arm). Moreover, msk RNA interference knockdown abolishes expression of the Wg target Ladybird (Lbe) in leg disc myoblasts. Collectively, our results provide strong evidence that Msk acts through the Wg signaling pathway to control myoblast pool size and muscle formation by regulating Arm stability or nuclear transport.

Study of serum sclerostin levels in association to entheseal ultrasonography in Egyptian psoriatic arthritis patients

IntroductionSerum sclerostin is a protein inhibitor of the wingless signaling pathway of bone formation whose role in osteoimmunology and inflammatory arthritides is still controversial.AimThe aim of the present study was to examine the relation of serum sclerostin as one member of the wingless signal protein inhibitors to arthritic and bony manifestation of psoriasis as a model of autoimmune inflammatory arthritis.Settings and designThis was a cross-sectional, prospective study.Patients and methodsThe study included 30 psoriatic arthritis (PsA) male patients whose mean age was 43.3±8.3 years and had a disease duration of 3.8±2.6 years, and 15 age-matched and sex-matched apparently healthy controls. Serum sclerostin was measured using the enzyme-linked immunosorbent assay. Disease activity was measured using the Disease Activity Index for Psoriatic Arthritis. Ultrasonography of enthesis at Leeds enthesitis sites and dual energy X-ray absorptiometry at the lumbar spine were also carried out for all patients.Statistical analysisThe independent t-test, Pearson’s correlation coefficient, and one-way analysis of variance were used for statistical analysis.ResultsThe serum sclerostin level was significantly higher in PsA patients compared with controls, with a mean of 0.64 and 0.37 ng/ml, respectively. Serum sclerostin correlated significantly with Disease Activity Index for Psoriatic Arthritis, ultrasonography inflammatory and damage scores, and dual energy X-ray absorptiometry at the lumbar spine.ConclusionSerum sclerostin could have a significant role in the development of inflammation-associated bone damage in PsA. Further follow-up studies are recommended to confirm the role of serum sclerostin in inflammation and bone damage in PsA patients and the factors that could regulate this autoimmune pathological event.

Effect of probiotic supplementation on growth and global gene expression in dairy cows

ABSTRACTUse of probiotic supplements as a non-chemical approach to promote health has increased in animal production. The present study evaluated the effect of oral probiotic administration on growth and global gene expression profile in dairy cows. Lactating Holstein-Friesian cows received a daily dose (50 ml) of a commercial probiotic (containing Lactobacillus acidophilus, Saccharomyces cerevisiae, Enterococcus faecium, Aspergillus oryza and Bacillus subtilis) for 60 days. A microarray experiment was performed with blood collected at day-0 and day-60. Although probiotic supplementation had no effect on body weight, PCV and total protein concentration in plasma (P > 0.05), per cent lymphocyte count increased (P < 0.05), and per cent neutrophil count decreased (P < 0.05) in probiotic-treated animals. Gene expression analysis identified 10,859 differentially expressed genes, 1168 up-regulated and 9691 down-regulated genes, respectively, following probiotic treatment. Single experiment pathway analysis identified 87 bovine pathways impacted by probiotic treatment. These pathways included the Toll-like receptor (TLR), inflammation response and Wingless signalling pathways. Oral administration of probiotics to dairy cows had a systemic effect on global gene expression, such as on genes involved in immunity and homeostasis. The results of this study show that the utilization of probiotics in animal agriculture impacts genes important to dairy cow health and production.

A compendium of developmental gene expression in Lake Malawi cichlid fishes

BackgroundLake Malawi cichlids represent one of a growing number of vertebrate models used to uncover the genetic and developmental basis of trait diversity. Rapid evolutionary radiation has resulted in species that share similar genomes but differ markedly in phenotypes including brains and behavior, nuptial coloration and the craniofacial skeleton. Research has begun to identify the genes, as well as the molecular and developmental pathways that underlie trait divergence.ResultsWe assemble a compendium of gene expression for Lake Malawi cichlids, across pharyngula (the phylotypic stage) and larval stages of development, encompassing hundreds of gene transcripts. We chart patterns of expression in Bone morphogenetic protein (BMP), Fibroblast growth factor (FGF), Hedgehog (Hh), Notch and Wingless (Wnt) signaling pathways, as well as genes involved in neurogenesis, calcium and endocrine signaling, stem cell biology, and numerous homeobox (Hox) factors—in three planes using whole-mount in situ hybridization. Because of low sequence divergence across the Malawi cichlid assemblage, the probes we employ are broadly applicable in hundreds of species. We tabulate gene expression across general tissue domains, and highlight examples of unexpected expression patterns.ConclusionsOn the heels of recently published genomes, this compendium of developmental gene expression in Lake Malawi cichlids provides a valuable resource for those interested in the relationship between evolution and development.

Signaling Molecules Governing Pluripotency and Early Lineage Commitments in Human Pluripotent Stem Cells.

Signaling in pluripotent stem cells is a complex and dynamic process involving multiple mediators, finely tuned to balancing pluripotency and differentiation states. Characterizing and modifying the necessary signaling pathways to attain desired cell types is required for stem-cell applications in various fields of regenerative medicine. These signals may help enhance the differentiation potential of pluripotent cells towards each of the embryonic lineages and enable us to achieve pure in vitro cultures of various cell types. This review provides a timely synthesis of recent advances into how maintenance of pluripotency in hPSCs is regulated by extrinsic cues, such as the fibroblast growth factor (FGF) and ACTIVIN signaling pathways, their interplay with other signaling pathways, namely, wingless- type MMTV integration site family (WNT) and mammalian target of rapamycin (mTOR), and the pathways governing the determination of multiple lineages.

Ryk receptors on unmyelinated nerve fibers mediate excitatory synaptic transmission and CCL2 release during neuropathic pain induced by peripheral nerve injury.

BackgroundNeuropathic pain is a major pathology of the central nervous system associated with neuroinflammation. Ryk (receptor-like tyrosine kinase) receptors act as repulsive axon-guidance molecules during development of central nervous system and neural injury. Increasing evidence suggests the potential involvement of Wnt/Ryk (wingless and Int) signaling in the pathogenesis of neuropathic pain. However, its underlying mechanism remains unknown.ResultsThe expression and location of Ryk receptor as well as its ligand Wnt1 were detected by qPCR, Western blot, and immunohistochemistry. We found that Ryk, a specific Wnt receptor, was expressed in IB4+ (Isolectin B4) and CGRP+ (calcitonin gene-related peptide) dorsal root ganglia neurons and their ascending unmyelinated fibers in the dorsal horn of the spinal cord. Ryk was upregulated after spinal nerve ligation surgery. Wnt1 was also increased in activated astrocytes in the dorsal horn after spinal nerve ligation. The presynaptic mechanism of Ryk in regulation of neuropathic pain was determined by electrophysiology in spinal slice. Spinal nerve ligation model was established, and the therapeutic potential of inhibiting Ryk receptor was determined. Spine-specific blocking of the Wnt/Ryk receptor signaling attenuated the spinal nerve ligation-induced mechanical allodynia but not thermal hyperalgesia. Further, it also blocked Ca2+-dependent signals including CaMKII and PKCγ, subsequent release of CCL2 (CCR-like protein) in the dorsal horn. An in vitro study showed that inactivating Ryk receptors with anti-Ryk antibodies or lentiviral Ryk shRNA led to the inactivation of Wnt1 for excitatory synaptic transmission in spinal slices and subsequent decrease in CCL2 expression in the dorsal root ganglia neurons.ConclusionThese studies demonstrate the existence of critical crosstalk between astrocytes and unmyelinated fibers, which indicate the presynaptic mechanism of Ryk in cytokine transmission of neuropathic pain and the therapeutic potential for Wnt/Ryk signaling pathway in the treatment of neuropathic pain.

The APC/C Coordinates Retinal Differentiation with G1 Arrest through the Nek2-Dependent Modulation of Wingless Signaling

SummaryThe cell cycle is coordinated with differentiation during animal development. Here we report a cell-cycle-independent developmental role for a master cell-cycle regulator, the anaphase-promoting complex or cyclosome (APC/C), in the regulation of cell fate through modulation of Wingless (Wg) signaling. The APC/C controls both cell-cycle progression and postmitotic processes through ubiquitin-dependent proteolysis. Through an RNAi screen in the developing Drosophila eye, we found that partial APC/C inactivation severely inhibits retinal differentiation independently of cell-cycle defects. The differentiation inhibition coincides with hyperactivation of Wg signaling caused by the accumulation of a Wg modulator, Drosophila Nek2 (dNek2). The APC/C degrades dNek2 upon synchronous G1 arrest prior to differentiation, which allows retinal differentiation through local suppression of Wg signaling. We also provide evidence that decapentaplegic signaling may posttranslationally regulate this APC/C function. Thus, the APC/C coordinates cell-fate determination with the cell cycle through the modulation of developmental signaling pathways.

Nystatin Modulates Genes in Immunity and Wingless Signaling Pathways in Cow Blood

Nystatin is an antifungal agent isolated from bacteria found in the dairy cow environment. It disrupts small platforms in the cell membrane, composed of sphingolipids and cholesterol known as lipid rafts. Pathogen recognition receptors (PRR) may be embedded in these lipid rafts. This study was conducted to evaluate the in vitro effects of the lipid raft inhibitor Nystatin, on the expression of genes in the innate and adaptive immunity and wnt signaling pathway in cow peripheral blood. Blood collected from four adult female Holstein-Friesian cows (n=4) was treated with 100ng/mL of Nystatin in vitro. Samples treated with Phosphate Buffer Saline served as control. Total protein concentration and prostaglandin E2in plasma were determined. Total RNA was isolated from cells and was used for cDNA synthesis. The effect of Nystatin on the expression of 84 genes on the cow Wingless signaling pathway and human innate and adaptive immunity arrays were assessed in cow blood using real-time PCR. Fold change in transcript abundance was calculated using Livak’s method. Nystatin was found to modulate transcription and translation of genes involved in homeostasis and immunity in cow blood. It also increased the concentration of total plasma protein and PGE2in cow blood and may thus have had a pro-inflammatory effect. This study provides evidence for the association between lipid raft inhibition and alterations in the wingless signaling pathway in ruminant blood. Furthermore, the results presented may inform antifungal drug design and use in cows.

Transcriptional Regulation of Frizzled-1 in Human Osteoblasts by Sp1.

The wingless pathway has a powerful influence on bone metabolism and is a therapeutic target in skeletal disorders. Wingless signaling is mediated in part through the Frizzled (FZD) receptor family. FZD transcriptional regulation is poorly understood. Herein we tested the hypothesis that Sp1 plays an important role in the transcriptional regulation of FZD1 expression in osteoblasts and osteoblast mineralization. To test this hypothesis, we conducted FZD1 promoter assays in Saos2 cells with and without Sp1 overexpression. We found that Sp1 significantly up-regulates FZD1 promoter activity in Saos2 cells. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift (EMSA) assays identified a novel and functional Sp1 binding site at -44 to -40 from the translation start site in the FZD1 promoter. The Sp1-dependent activation of the FZD1 promoter was abolished by mithramycin A (MMA), an antibiotic affecting both Sp1 binding and Sp1 protein levels in Saos2 cells. Similarly, down-regulation of Sp1 in hFOB cells resulted in less FZD1 expression and lower alkaline phosphatase activity. Moreover, over-expression of Sp1 increased FZD1 expression and Saos2 cell mineralization while MMA decreased Sp1 and FZD1 expression and Saos2 cell mineralization. Knockdown of FZD1 prior to Sp1 overexpression partially abolished Sp1 stimulation of osteoblast differentiation markers. Taken together, our results suggest that Sp1 plays a role in human osteoblast differentiation and mineralization, which is at least partially mediated by Sp1-dependent transactivation of FZD1.

Altered Expression of PRKX, WNT3 and WNT16 in Human Nodular Basal Cell Carcinoma.

Nodular and superficial are the most common subtypes of basal cell carcinoma (BCC). Signaling pathways such as Hedgehog (HH) and Wingless (WNT) signaling are associated with BCC phenotypic variation. The aim of the study was to evaluate of the expression profiles of 84 genes related to the WNT and HH signaling pathways in patients with nodular and superficial BCC. A total of 58 BCCs and 13 samples of normal skin were evaluated by quantitative real-time polymerase chain reaction (qPCR) to detect the gene-expression profile. qPCR array showed segregation in BCC subtypes compared to healthy skin. PRKX, WNT3 and WNT16 were significantly (p<0.05) altered: PRKX was up-regulated, and WNT3 and WNT16 were down-regulated in nodular BCC. PRKX, WNT3 and WNT16 genes, belonging to the WNT signaling pathway, are involved in the tumorigenic process of nodular BCC.

The exon junction complex regulates the splicing of cell polarity gene dlg1 to control Wingless signaling in development.

Wingless (Wg)/Wnt signaling is conserved in all metazoan animals and plays critical roles in development. The Wg/Wnt morphogen reception is essential for signal activation, whose activity is mediated through the receptor complex and a scaffold protein Dishevelled (Dsh). We report here that the exon junction complex (EJC) activity is indispensable for Wg signaling by maintaining an appropriate level of Dsh protein for Wg ligand reception in Drosophila. Transcriptome analyses in Drosophila wing imaginal discs indicate that the EJC controls the splicing of the cell polarity gene discs large 1 (dlg1), whose coding protein directly interacts with Dsh. Genetic and biochemical experiments demonstrate that Dlg1 protein acts independently from its role in cell polarity to protect Dsh protein from lysosomal degradation. More importantly, human orthologous Dlg protein is sufficient to promote Dvl protein stabilization and Wnt signaling activity, thus revealing a conserved regulatory mechanism of Wg/Wnt signaling by Dlg and EJC.

Wnt Lipidation and Modifiers in Intestinal Carcinogenesis and Cancer

The wingless (Wnt) signaling is suggested as a fundamental hierarchical pathway in regulation of proliferation and differentiation of cells. The Wnt ligands are small proteins of about 40 kDa essentially for regulation and initiation of the Wnt activity. They are secreted proteins requiring acylation for activity in the Wnt signaling cascade and for functional interactivity with transmembrane proteins. Dual lipidation is important for posttranslational activation of the overwhelming number of Wnt proteins and is probably involved in their spatial distribution. The intestinal mucosa, where Wnt signaling is essential in configuration and maintenance, is an established model to study Wnt proteins and their role in carcinogenesis and cancer. The intestinal crypt-villus/crypt-plateau axis, a cellular system with self-renewal, proliferation, and differentiation, is tightly coordinated by a Wnt gradient. In the review, some attention is given to Wnt3, Wnt3A, and Wnt2B as important members of the Wnt family to address the role of lipidation and modifiers of Wnt proteins in intestinal carcinogenesis. Wnt3 is an important player in establishing the Wnt gradient in intestinal crypts and is mainly produced by Paneth cells. Wnt2B is characterized as a mitochondrial protein and shuttles between mitochondria and the nucleus. Porcupine and ACSL5, a long-chain fatty acid activating enzyme, are introduced as modifiers of Wnts and as interesting strategy to targeting Wnt-driven carcinogenesis.

Evolution of the mandibular appendage in fig wasps (Hymenoptera: Agaonidae)

The phylogenetic value of the conformation of the mandibular appendages, the number of mandibular glands and other head characters in the Agaonidae are examined. The phylogenetic arrangement suggests that the preagaonid had a normal bidentate mandible with two glands, and a undistinct facial groove as in sorne Diaziella (Sycoecinae), Sycophaga (Sycophaginae) and in related chalcidoid non-pollinating fig wasps. lt also had thirteen-segmented antennae;' a long scape, several times ionger than wide a long triangular pedicel, two or three anelli and eight flagellomeres with sensilla (as uniquely found in Tetrapus). The mandibular appendage apparently co-evolved with the development oi the ostiolum of the syconium and the first mandibular appendage was fixed and had ridges or lameUae. A flexible hinge evolved later at its base. The polygamous males were wingless with extendible (solenogastrus) abdomen and mate inside the galls. These characters are also found in most Sycophaginae. The ancestor of Aganoidae was probably a primary sycophilous wasp, with dorsoventral depressed head, thorax and abdomen, that oviposit through the stylar channel as stiU Sycophaga sycomori does. Sycophaga wasps with its apterous and polygamous males seem to be the sister group of Agaonidae. The Agaonidae females are characterized by their mandibular appendage and the antennal process. They have a prognathous head with gula. The males are wingless polygamous and solenogastrous

Unipolar distributions of junctional Myosin II identify cell stripe boundaries that drive cell intercalation throughout Drosophila axis extension.

Convergence and extension movements elongate tissues during development. Drosophila germ-band extension (GBE) is one example, which requires active cell rearrangements driven by Myosin II planar polarisation. Here, we develop novel computational methods to analyse the spatiotemporal dynamics of Myosin II during GBE, at the scale of the tissue. We show that initial Myosin II bipolar cell polarization gives way to unipolar enrichment at parasegmental boundaries and two further boundaries within each parasegment, concomitant with a doubling of cell number as the tissue elongates. These boundaries are the primary sites of cell intercalation, behaving as mechanical barriers and providing a mechanism for how cells remain ordered during GBE. Enrichment at parasegment boundaries during GBE is independent of Wingless signaling, suggesting pair-rule gene control. Our results are consistent with recent work showing that a combinatorial code of Toll-like receptors downstream of pair-rule genes contributes to Myosin II polarization via local cell-cell interactions. We propose an updated cell-cell interaction model for Myosin II polarization that we tested in a vertex-based simulation.

WINGLESS (WNT) signaling is a progesterone target for rat uterine stromal cell proliferation.

Preparation of mammalian uterus for embryo implantation requires a precise sequence of cell proliferation. In rodent uterus, estradiol stimulates proliferation of epithelial cells. Progesterone operates as a molecular switch and redirects proliferation to the stroma by down-regulating glycogen synthase kinase-3β (GSK-3β) and stimulating β-catenin accumulation in the periluminal stromal cells. In this study, the WNT signal involved in the progesterone-dependent proliferative switch was investigated. Transcripts of four candidate Wnt genes were measured in the uteri from ovariectomized (OVX) rats, progesterone-pretreated (3 days of progesterone, 2mg/daily) rats, and progesterone-pretreated rats given a single dose (0.2µg) of estradiol. The spatial distribution of the WNT proteins was determined in the uteri after the same treatments. Wnt5a increased in response to progesterone and the protein emerged in the periluminal stromal cells of progesterone-pretreated rat uteri. To investigate whether WNT5A was required for proliferation, uterine stromal cell lines were stimulated with progesterone (1µM) and fibroblast growth factor (FGF, 50ng/mL). Proliferating stromal cells expressed a two-fold increase in WNT5A protein at 12h post stimulation. Stimulated stromal cells were cultured with actinomycin D (25µg/mL) to inhibit new RNA synthesis. Relative Wnt5a expression increased at 4 and 6 h of culture, suggesting that progesterone plus FGF preferentially increased Wnt5a mRNA stability. Knockdown of Wnt5a in uterine stromal cell lines inhibited stromal cell proliferation and decreased Wnt5a mRNA. The results indicate that progesterone initiates and synchronizes uterine stromal cell proliferation by increasing WNT5A expression and signaling.

Godzilla-dependent transcytosis promotes Wingless signalling in Drosophila wing imaginal discs.

The apical and basolateral membranes of epithelia are insulated from each other, preventing the transfer of extracellular proteins from one side to the other1. Thus, a signalling protein produced apically is not expected to reach basolateral receptors. Evidence suggests that Wingless, the main Drosophila Wnt is secreted apically in the embryonic epidermis2, 3. However, in the wing imaginal disc epithelium, Wingless is mostly seen on the basolateral membrane where it spreads from secreting to receiving cells 4, 5. Here we examine the apico-basal movement of Wingless in Wingless-producing cells of wing imaginal discs. We find that it is presented first on the apical surface before making its way to the basolateral surface, where it is released and allowed to interact with signalling receptors. We show that Wingless transcytosis involves Dynamin-dependent endocytosis from the apical surface. Subsequent trafficking from early apical endosomes to the basolateral surface requires Godzilla, a member of the RNF family of membrane-anchored E3 ubiquitin ligases. Without such transport, Wingless signalling is strongly reduced in this tissue.