Comparing the effects of three neonicotinoids on embryogenesis of the South African clawed frog Xenopus laevis

Neonicotinoids (NEOs) are widely used insecticides that are ubiquitous in agricultural use. Since NEOs are found in natural waters as well as in tap water and human urine in regions where NEOs are widely used, NEOs pose a potential hazard to non-target organisms such as animals and humans. Some of the commonly detected NEOs are imidacloprid (IMD), thiamethoxam (TMX), and its metabolite clothianidin (CLO). Although previously published scientific information, including an assessment of the environmental risks, particularly for bees, had resulted in a ban on the outdoor use of these three NEOs in the EU - their use is now only permitted in closed greenhouses - these NEOs continue to be used in agriculture in many other parts of the world. Therefore, a detailed study and comparison of the effects of NEOs on the embryonic development of non-target organisms is needed to further define the risk profiles. Embryos of the South African clawed frog Xenopus laevis, a well-established aquatic model, were exposed to different concentrations of IMD, TMX, or CLO (0.1-100 mg/L) to study and compare the possible effects of a single contaminant in natural water bodies on early embryogenesis. The results included a reduced body length, a smaller orbital space, impaired cranial cartilage and nerves, and an altered heart structure and function. At the molecular level, NEO exposure partially resulted in an altered expression of tissue-specific factors, which are involved in eye, cranial placode, and heart development. Our results suggest that the NEOs studied negatively affect the embryonic development of the non-target organism X. laevis. Since pesticides, especially NEOs, pollute the environment worldwide, it is suggested that they are strictly controlled and monitored in the areas where they are used. In addition, the question arises as to whether pesticide metabolites also pose a risk to the environment and need to be investigated further so that they can be taken into account when registering ingredients.

Prdm15 acts upstream of Wnt4 signaling in anterior neural development of Xenopus laevis

Mutations in PRDM15 lead to a syndromic form of holoprosencephaly (HPE) known as the Galloway-Mowat syndrome (GAMOS). While a connection between PRDM15, a zinc finger transcription factor, and WNT/PCP signaling has been established, there is a critical need to delve deeper into their contributions to early development and GAMOS pathogenesis. We used the South African clawed frog Xenopus laevis as the vertebrate model organism and observed that prdm15 was enriched in the tissues and organs affected in GAMOS. Furthermore, we generated a morpholino oligonucleotide-mediated prdm15 knockdown model showing that the depletion of Prdm15 leads to abnormal eye, head, and brain development, effectively recapitulating the anterior neural features in GAMOS. An analysis of the underlying molecular basis revealed a reduced expression of key genes associated with eye, head, and brain development. Notably, this reduction could be rescued by the introduction of wnt4 RNA, particularly during the induction of the respective tissues. Mechanistically, our data demonstrate that Prdm15 acts upstream of both canonical and non-canonical Wnt4 signaling during anterior neural development. Our findings describe severe ocular and anterior neural abnormalities upon Prdm15 depletion and elucidate the role of Prdm15 in canonical and non-canonical Wnt4 signaling.

Changes in DNA methylation hallmark alterations in chromatin accessibility and gene expression for eye lens differentiation

Background

Methylation at cytosines (mCG) is a well-known regulator of gene expression, but its requirements for cellular differentiation have yet to be fully elucidated. A well-studied cellular differentiation model system is the eye lens, consisting of a single anterior layer of epithelial cells that migrate laterally and differentiate into a core of fiber cells. Here, we explore the genome-wide relationships between mCG methylation, chromatin accessibility and gene expression during differentiation of eye lens epithelial cells into fiber cells.

Results

Whole genome bisulfite sequencing identified 7621 genomic loci exhibiting significant differences in mCG levels between lens epithelial and fiber cells. Changes in mCG levels were inversely correlated with the differentiation state-specific expression of 1285 genes preferentially expressed in either lens fiber or lens epithelial cells (Pearson correlation r = − 0.37, p < 1 × 10^–42). mCG levels were inversely correlated with chromatin accessibility determined by assay for transposase-accessible sequencing (ATAC-seq) (Pearson correlation r = − 0.86, p < 1 × 10^–300). Many of the genes exhibiting altered regions of DNA methylation, chromatin accessibility and gene expression levels in fiber cells relative to epithelial cells are associated with lens fiber cell structure, homeostasis and transparency. These include lens crystallins (CRYBA4, CRYBB1, CRYGN, CRYBB2), lens beaded filament proteins (BFSP1, BFSP2), transcription factors (HSF4, SOX2, HIF1A), and Notch signaling pathway members (NOTCH1, NOTCH2, HEY1, HES5). Analysis of regions exhibiting cell-type specific alterations in DNA methylation revealed an overrepresentation of consensus sequences of multiple transcription factors known to play key roles in lens cell differentiation including HIF1A, SOX2, and the MAF family of transcription factors.

Conclusions

Collectively, these results link DNA methylation with control of chromatin accessibility and gene expression changes required for eye lens differentiation. The results also point to a role for DNA methylation in the regulation of transcription factors previously identified to be important for lens cell differentiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13072-022-00440-z.

Case Report: A Novel Missense Variant in the SIPA1L3 Gene Associated With Cataracts in a Chinese Family

The signal-induced proliferation-associated 1-like 3 (SIPA1L3) gene that encodes a putative Rap GTPase-activating protein (RapGAP) has been associated with congenital cataract and eye development abnormalities. However, our current understanding of the mutation spectrum of SIPA1L3 associated with eye defects is limited. By using whole-exome sequencing plus Sanger sequencing validation, we identified a novel heterozygous c.1871A > G (p.Lys624Arg) variation within the predicted RapGAP domain of SIPA1L3 in the proband with isolated juvenile-onset cataracts from a three-generation Chinese family. In this family, the proband's father and grandmother were also heterozygous for the c.1871A > G variation and affected by cataracts varying in morphology, severity, and age of onset. Sequence alignment shows that the Lys 624 residue of SIPA1L3 is conserved across the species. Based on the resolved structure of Rap1–Rap1GAP complex, homology modeling implies that the Lys 624 residue is structurally homologous to the Lys 194 of Rap1GAP, a highly conserved lysine residue that is involved in the interface between Rap1 and Rap1GAP and critical for the affinity to Rap·GTP. We reasoned that arginine substitution of lysine 624 might have an impact on the SIPA1L3-Rap·GTP interaction, thereby affecting the regulatory function of SIPA1L3 on Rap signaling. Collectively, our finding expands the mutation spectrum of SIPA1L3 and provides new clues to the molecular mechanisms of SIPA1L3-related cataracts. Further investigations are warranted to validate the functional alteration of the p.Lys624Arg variant of SIPA1L3.

A functional map of genomic HIF1α-DNA complexes in the eye lens revealed through multiomics analysis

BACKGROUND

During eye lens development the embryonic vasculature regresses leaving the lens without a direct oxygen source. Both embryonically and throughout adult life, the lens contains a decreasing oxygen gradient from the surface to the core that parallels the natural differentiation of immature surface epithelial cells into mature core transparent fiber cells. These properties of the lens suggest a potential role for hypoxia and the master regulator of the hypoxic response, hypoxia-inducible transcription factor 1 (HIF1), in the regulation of genes required for lens fiber cell differentiation, structure and transparency. Here, we employed a multiomics approach combining CUT&RUN, RNA-seq and ATACseq analysis to establish the genomic complement of lens HIF1α binding sites, genes activated or repressed by HIF1α and the chromatin states of HIF1α-regulated genes.

RESULTS

CUT&RUN analysis revealed 8375 HIF1α-DNA binding complexes in the chick lens genome. One thousand one hundred ninety HIF1α-DNA binding complexes were significantly clustered within chromatin accessible regions (χ2 test p < 1 × 10- 55) identified by ATACseq. Formation of the identified HIF1α-DNA complexes paralleled the activation or repression of 526 genes, 116 of which contained HIF1α binding sites within 10kB of the transcription start sites. Some of the identified HIF1α genes have previously established lens functions while others have novel functions never before examined in the lens. GO and pathway analysis of these genes implicate HIF1α in the control of a wide-variety of cellular pathways potentially critical for lens fiber cell formation, structure and function including glycolysis, cell cycle regulation, chromatin remodeling, Notch and Wnt signaling, differentiation, development, and transparency.

CONCLUSIONS

These data establish the first functional map of genomic HIF1α-DNA complexes in the eye lens. They identify HIF1α as an important regulator of a wide-variety of genes previously shown to be critical for lens formation and function and they reveal a requirement for HIF1α in the regulation of a wide-variety of genes not yet examined for lens function. They support a requirement for HIF1α in lens fiber cell formation, structure and function and they provide a basis for understanding the potential roles and requirements for HIF1α in the development, structure and function of more complex tissues.

Retinol binding protein 1 affects Xenopus anterior neural development via all-trans retinoic acid signaling

BACKGROUND

Retinol binding protein 1 (Rbp1) acts as an intracellular regulator of vitamin A metabolism and retinoid transport. In mice, Rbp1 deficiency decreases the capacity of hepatic stellate cells to take up all-trans retinol and sustain retinyl ester stores. Furthermore, Rbp1 is crucial for visual capacity. Although the function of Rbp1 has been studied in the mature eye, its role during early anterior neural development has not yet been investigated in detail.

RESULTS

We showed that rbp1 is expressed in the eye, anterior neural crest cells (NCCs) and prosencephalon of the South African clawed frog Xenopus laevis. Rbp1 knockdown led to defects in eye formation, including microphthalmia and disorganized retinal lamination, and to disturbed induction and differentiation of the eye field, as shown by decreased rax and pax6 expression. Furthermore, it resulted in reduced rax expression in the prosencephalon and affected cranial cartilage. Rbp1 inhibition also interfered with neural crest induction and migration, as shown by twist and slug. Moreover, it led to a significant reduction of the all-trans retinoic acid target gene pitx2 in NCC-derived periocular mesenchyme. The Rbp1 knockdown phenotypes were rescued by pitx2 RNA co-injection.

CONCLUSION

Rbp1 is crucial for the development of the anterior neural tissue.

Long non-coding RNA CCAT2 promotes prostate cancer cell proliferation and invasion by regulating the Wnt/β-catenin signaling pathway

Long non-coding RNA colon cancer associated transcript 2 (CCAT2) is dysregulated in a number of different types of human cancer, and affects cancer progression via the Wnt/β-catenin signaling pathway. However, the roles of CCAT2 and the Wnt/β-catenin signaling pathway in prostate cancer (PCa) are not completely understood. The present study aimed to investigate the potential mechanism of CCAT2 in PCa. In the present study, the reverse transcription-quantitative PCR (RT-qPCR) results indicated that CCAT2 expression was significantly upregulated in PCa tissues, and DU145 and PC3 cell lines compared with normal prostate tissues and the epithelial RWPE-1 cell line, respectively. Functional assays indicated that CCAT2 downregulation inhibited DU145 and PC3 cell proliferation, cell cycle, migration and invasion. In addition, the luciferase reporter assay, RT-qPCR and western blotting results indicated that CCAT2 regulated transcription factor 7 like 2 (TCF7L2) expression by binding to microRNA-217. Further western blotting and TOPFlash assays indicated that CCAT2-knockdown inhibited the Wnt/β-catenin signaling pathway in DU145 and PC3 cell lines by inhibiting the expression of TCF7L2. However, CCAT2-knockdown-mediated effects were reversed by the Wnt/β-catenin signaling pathway activator lithium chloride (LiCl). Further cell experiments suggested that LiCl treatment reversed CCAT2-knockdown-mediated inhibition of PCa cell proliferation, cell cycle, epithelial-mesenchymal transition, migration and invasion. Overall, the results indicated that CCAT2 regulated PCa via the Wnt/β-catenin signaling pathway; therefore, CCAT2 may exhibit key role during the progression of PCa and may serve as a therapeutic target for the disease.

Modeling ocular lens disease in Xenopus

BACKGROUND

Ocular lens clouding is termed as cataract, which depending on the onset, is classified as congenital or age-related. Developing new cataract treatments requires new models. Thus far, Xenopus embryos have not been evaluated as a system for studying cataract.

RESULTS

We characterized the developmental process of lens formation in Xenopus laevis tailbuds and tadpoles, and we disrupted the orthologues of three mammalian cataract-linked genes in F0 by CRISPR/Cas9. We assessed the consequences of gene inactivation by combining external examination with histochemical analyses and functional vision assays. Inactivating the key metazoan eye development transcription factor gene pax6 produces a strong eye phenotype including an absence of eye tissue. Inactivating the genes for gap-junction protein and a nuclease, gja8 and dnase2b, produces lens defects that share several features of human cataracts, including impaired vision acuity, nuclei retention in lens fiber cells, and actin fibers disorganization. We tested the potential improvement of the visual acuity of gja8 crispant tadpoles upon treatment with the molecular chaperone 4-phenylbutyrate.

CONCLUSION

Xenopus is a valuable model organism to understand the molecular pathology of congenital eye defects, including cataracts, and to screen molecules with a potential to prevent or reverse cataracts.

Localization Patterns of Sumoylation Enzymes E1, E2 and E3 in Ocular Cell Lines Predict Their Functional Importance

PURPOSE

It is well established now that protein sumoylation acts as an important regulatory mechanism mediating control of ocular development through regulation of multiple transcription factors. Yet the functional mechanisms of each factor modulated remain to be further explored using the available in vitro systems. In this regard, various ocular cell lines including HLE, FHL124, αTN4-1, N/N1003A and ARPE-19 have been demonstrated to be useful for biochemical and molecular analyses of normal physiology and pathogenesis. We have recently examined that these cell lines express a full set of sumoylation enzymes E1, E2 and E3. Following this study, here we have examined the localization of these enzymes and determined their differential localization patterns in these major ocular cell lines.

METHODS

The 5 major ocular cell lines were cultured in Dulbecco's modified Eagle's medium (DMEM) containing fetal bovine serum (FBS) or rabbit serum (RBS) and 1% Penicillin- Streptomycin. The localization of the 3 major sumoylation enzymes in the 5 major ocular cell lines were determined with immunohistochemistry. The images were captured with a Zeiss LSM 880 confocal microscope.

RESULTS

we have obtained the following results: 1) The sumoylation enzymes SAE1, UBC9 and PIAS1 are distributed in both nucleus and cytoplasm, with a much higher level concentrated in the nucleus and the neighboring cellular organelle zone in all cell lines; 2) The sumoylation enzyme UBA2 was highly concentrated in both cytoplasm membrane, cytoskeleton and nucleus of all cell lines; 3) The ligase E3, RanBP2 was exclusively localized in the nucleus with homogeneous distribution.

CONCLUSIONS

Our results for the first time established the differential localization patterns of the three types of sumoylation enzymes in 5 major ocular cell lines. Our establishment of the differential localization patterns of the three types of sumoylation enzymes in these cell lines help to predict their functional importance of sumoylation in the vision system. Together, our results demonstrate that these cell lines can be used for assay systems to explore the functional mechanisms of sumoylation mediating ocular development and pathogenesis.

iSyTE 2.0: a database for expression-based gene discovery in the eye

Although successful in identifying new cataract-linked genes, the previous version of the database iSyTE (integrated Systems Tool for Eye gene discovery) was based on expression information on just three mouse lens stages and was functionally limited to visualization by only UCSC-Genome Browser tracks. To increase its efficacy, here we provide an enhanced iSyTE version 2.0 (URL: http://research.bioinformatics.udel.edu/iSyTE) based on well-curated, comprehensive genome-level lens expression data as a one-stop portal for the effective visualization and analysis of candidate genes in lens development and disease. iSyTE 2.0 includes all publicly available lens Affymetrix and Illumina microarray datasets representing a broad range of embryonic and postnatal stages from wild-type and specific gene-perturbation mouse mutants with eye defects. Further, we developed a new user-friendly web interface for direct access and cogent visualization of the curated expression data, which supports convenient searches and a range of downstream analyses. The utility of these new iSyTE 2.0 features is illustrated through examples of established genes associated with lens development and pathobiology, which serve as tutorials for its application by the end-user. iSyTE 2.0 will facilitate the prioritization of eye development and disease-linked candidate genes in studies involving transcriptomics or next-generation sequencing data, linkage analysis and GWAS approaches.

Peptidomic analysis of zebrafish embryos exposed to polychlorinated biphenyls and their impact on eye development

Polychlorinated biphenyls (PCBs), a class of persistent organic pollutant, are closely related to abnormal eye development in children. However, little is known regarding the role of peptides in the development of PCB-induced ocular dysplasia. To characterize the nature of PCB exposure on peptides involved in the development of the ocular system, we used liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) to detect differential expression of peptides between normal and PCB-exposed zebrafish embryos. A total of 7900 peptides were analyzed, 90 of which were differentially expressed, with 29 being up-regulated and 61 down-regulated. These peptides were investigated using ingenuity pathway analysis (IPA) and gene ontology (GO) analysis to explore their role in eye development. This study identified 18 peptides associated with the development of the optic nerve and ocular system in the PCB-exposure group, as well as 10 peptides that are located in the functional domain of their precursor proteins. These peptides provide potential biomarkers for the treatment of ocular dysplasia caused by PCBs and may help us understand the mechanism of abnormal eye development caused by organic pollutants.

Physiological effects of KDM5C on neural crest migration and eye formation during vertebrate development

Background

Lysine-specific histone demethylase 5C (KDM5C) belongs to the jumonji family of demethylases and is specific for the di- and tri-demethylation of lysine 4 residues on histone 3 (H3K4 me2/3). KDM5C is expressed in the brain and skeletal muscles of humans and is associated with various biologically significant processes. KDM5C is known to be associated with X-linked mental retardation and is also involved in the development of cancer. However, the developmental significance of KDM5C has not been explored yet. In the present study, we investigated the physiological roles of KDM5C during Xenopus laevis embryonic development.

Results

Loss-of-function analysis using kdm5c antisense morpholino oligonucleotides indicated that kdm5c knockdown led to small-sized heads, reduced cartilage size, and malformed eyes (i.e., small-sized and deformed eyes). Molecular analyses of KDM5C functional roles using whole-mount in situ hybridization, β-galactosidase staining, and reverse transcription-polymerase chain reaction revealed that loss of kdm5c resulted in reduced expression levels of neural crest specifiers and genes involved in eye development. Furthermore, transcriptome analysis indicated the significance of KDM5C in morphogenesis and organogenesis.

Conclusion

Our findings indicated that KDM5C is associated with embryonic development and provided additional information regarding the complex and dynamic gene network that regulates neural crest formation and eye development. This study emphasizes the functional significance of KDM5C in Xenopus embryogenesis; however, further analysis is needed to explore the interactions of KDM5C with specific developmental genes.

Electronic supplementary material

The online version of this article (10.1186/s13072-018-0241-x) contains supplementary material, which is available to authorized users.

RNA sequencing-based transcriptomic profiles of embryonic lens development for cataract gene discovery

Isolated or syndromic congenital cataracts are heterogeneous developmental defects, making the identification of the associated genes challenging. In the past, mouse lens expression microarrays have been successfully applied in bioinformatics tools (e.g., iSyTE) to facilitate human cataract-associated gene discovery. To develop a new resource for geneticists, we report high-throughput RNA sequencing (RNA-seq) profiles of mouse lens at key embryonic stages (E)10.5 (lens pit), E12.5 (primary fiber cell differentiation), E14.5 and E16.5 (secondary fiber cell differentiation). These stages capture important events as the lens develops from an invaginating placode into a transparent tissue. Previously, in silico whole-embryo body (WB)-subtraction-based "lens-enriched" expression has been effective in prioritizing cataract-linked genes. To apply an analogous approach, we generated new mouse WB RNA-seq datasets and show that in silico WB subtraction of lens RNA-seq datasets successfully identifies key genes based on lens-enriched expression. At ≥2 counts-per-million expression, ≥1.5 log₂ fold-enrichment (p < 0.05) cutoff, E10.5 lens exhibits 1401 enriched genes (17% lens-expressed genes), E12.5 lens exhibits 1937 enriched genes (22% lens-expressed genes), E14.5 lens exhibits 2514 enriched genes (31% lens-expressed genes), and E16.5 lens exhibits 2745 enriched genes (34% lens-expressed genes). Biological pathway analysis identified genes associated with lens development, transcription regulation and signaling pathways, among other functional groups. Furthermore, these new RNA-seq data confirmed high expression of established cataract-linked genes and identified new potential regulators in the lens. Finally, we developed new lens stage-specific UCSC Genome Brower annotation tracks and made these publicly accessible through iSyTE ( https://research.bioinformatics.udel.edu/iSyTE/ ) for user-friendly visualization of lens gene expression/enrichment to prioritize genes from high-throughput data from cataract cases.

Nosip functions during vertebrate eye and cranial cartilage development

BACKGROUND

The nitric oxide synthase interacting protein (Nosip) has been associated with diverse human diseases including psychological disorders. In line, early neurogenesis of mouse and Xenopus is impaired upon Nosip deficiency. Nosip knockout mice show craniofacial defects and the down-regulation of Nosip in the mouse and Xenopus leads to microcephaly. Until now, the exact underlying molecular mechanisms of these malformations were still unknown.

RESULTS

Here, we show that nosip is expressed in the developing ocular system as well as the anterior neural crest cells of Xenopus laevis. Furthermore, Nosip inhibition causes severe defects in eye formation in the mouse and Xenopus. Retinal lamination as well as dorso-ventral patterning of the retina were affected in Nosip-depleted Xenopus embryos. Marker gene analysis using rax, pax6 and otx2 reveals an interference with the eye field induction and differentiation. A closer look on Nosip-deficient Xenopus embryos furthermore reveals disrupted cranial cartilage structures and an inhibition of anterior neural crest cell induction and migration shown by twist, snai2, and egr2. Moreover, foxc1 as downstream factor of retinoic acid signalling is affected upon Nosip deficiency.

CONCLUSIONS

Nosip is a crucial factor for the development of anterior neural tissue such the eyes and neural crest cells. Developmental Dynamics 247:1070-1082, 2018. © 2018 Wiley Periodicals, Inc.

Signaling and Gene Regulatory Networks in Mammalian Lens Development

Ocular lens development represents an advantageous system in which to study regulatory mechanisms governing cell fate decisions, extracellular signaling, cell and tissue organization, and the underlying gene regulatory networks. Spatiotemporally regulated domains of BMP, FGF, and other signaling molecules in late gastrula-early neurula stage embryos generate the border region between the neural plate and non-neural ectoderm from which multiple cell types, including lens progenitor cells, emerge and undergo initial tissue formation. Extracellular signaling and DNA-binding transcription factors govern lens and optic cup morphogenesis. Pax6, c-Maf, Hsf4, Prox1, Sox1, and a few additional factors regulate the expression of the lens structural proteins, the crystallins. Extensive crosstalk between a diverse array of signaling pathways controls the complexity and order of lens morphogenetic processes and lens transparency.

Silencing of long non-coding RNA CCAT2 depressed malignancy of oral squamous cell carcinoma via Wnt/β-catenin pathway

Oral squamous cell carcinoma is a common and lethal malignancy affecting the head and neck region. CCAT2 (colon cancer-associated transcript 2) gene is affiliated with long non-coding RNAs, which are often found to have important regulatory roles in cancers. This study aims to assess the expression and clinical significance of CCAT2 gene, identify its malignant biological behaviors, and explore the possible mechanisms in oral squamous cell carcinoma. CCAT2 expression was detected by quantitative real-time polymerase chain reaction, and its relationship with clinical factors was assayed using the Kaplan-Meier survival curve. The biological behaviors of CCAT2 and its potential mechanisms in oral squamous cell carcinoma were explored by the combined use of CCAT2 knockdown technology and the Wnt/β-catenin pathway agonist lithium chloride (LiCl). Our results showed that CCAT2 functioning as a potential oncogene was upregulated in oral squamous cell carcinoma. CCAT2 with high expression level was correlated with poor differentiation, higher T stage, and clinical stage, which made CCAT2 to be a prognostic biomarker in oral squamous cell carcinoma. LiCl-activated Wnt/β-catenin signaling pathway could partly restore the CCAT2-mediated malignant biological behaviors of oral squamous cell carcinoma cells by suppressing β-catenin, CCND1, and MYC and activating glycogen synthase kinase 3 beta expression. These findings might assist in the discovery of novel potential diagnostic and therapeutic target for oral squamous cell carcinoma, thereby improve the effects of clinical treatment in patients.

Frizzled 3 acts upstream of Alcam during embryonic eye development

Formation of a functional eye during vertebrate embryogenesis requires different processes such as cell differentiation, cell migration, cell-cell interactions as well as intracellular signalling processes. It was previously shown that the non-canonical Wnt receptor Frizzled 3 (Fzd3) is required for proper eye formation, however, the underlying mechanism is poorly understood. Here we demonstrate that loss of Fzd3 induces severe malformations of the developing eye and that this defect is phenocopied by loss of the activated leukocyte cell adhesion molecule (Alcam). Promoter analysis revealed the presence of a Fzd3 responsive element within the alcam promoter, which is responsible for alcam expression during anterior neural development. In-depth analysis identified the jun N-terminal protein kinase 1 (JNK1) and the transcription factor paired box 2 (Pax2) to be important for the activation of alcam expression. Altogether our study reveals that alcam is activated through non-canonical Wnt signalling during embryonic eye development in Xenopus laevis and shows that this pathway plays a similar role in different tissues.