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Abstract
Wnts are secreted proteins that control stem cell maintenance, cell fate decisions, and growth during development and adult homeostasis. Wnts carry a post-translational modification not seen in any other secreted protein: during biosynthesis, they are appended with a palmitoleoyl moiety that is required for signaling but also impairs solubility and hence diffusion in the extracellular space. In some contexts, Wnts act only in a juxtacrine manner but there are also instances of long range action. Several proteins and processes ensure that active Wnts reach the appropriate target cells. Some, like Porcupine, Wntless, and Notum are dedicated to Wnt function; we describe their activities in molecular detail. We also outline how the cell infrastructure (secretory, endocytic, and retromer pathways) contribute to the progression of Wnts from production to delivery. We then address how Wnts spread in the extracellular space and form a signaling gradient despite carrying a hydrophobic moiety. We highlight particularly the role of lipid-binding Wnt interactors and heparan sulfate proteoglycans. Finally, we briefly discuss how evolution might have led to the emergence of this unusual signaling pathway.
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2
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Velloso I, Han W, He X, Abreu JG. The role of Wnt signaling in Xenopus neural induction. Curr Top Dev Biol 2023; 153:229-254. [PMID: 36967196 DOI: 10.1016/bs.ctdb.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Development of the central nervous system in amphibians has called attention from scientists for over a century. Interested in the matter of embryonic inductions, Hans Spemann and Hilde Mangold found out that the dorsal blastopore lip of the salamander's embryo has organizer properties. Such an ectopic graft could induce structures in the host embryo, including a neural tube overlying the notochord of a perfect secondary body axis. A couple of decades later, the frog Xenopus laevis emerged as an excellent embryological experimental model and seminal concepts involving embryonic inductions began to be revealed. The so-called primary induction is, in fact, a composition of signaling and inductive events that are triggered as soon as fertilization takes place. In this regard, since early 1990s an intricate network of signaling pathways has been built. The Wnt pathway, which began to be uncovered in cancer biology studies, is crucial during the establishment of two signaling centers in Xenopus embryogenesis: Nieuwkoop center and the blastula chordin noggin expression center (BCNE). Here we will discuss the historical events that led to the discovery of those centers, as well as the molecular mechanisms by which they operate. This chapter highlights the cooperation of both signaling centers with potential to be further explored in the future. We aim to address the essential morphological transformation during gastrulation and neurulation as well as the role of Wnt signaling in patterning the organizer and the neural plate.
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Affiliation(s)
- Ian Velloso
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Wonhee Han
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Xi He
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States.
| | - Jose G Abreu
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
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3
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Hirano S, Mii Y, Charras G, Michiue T. Alignment of the cell long axis by unidirectional tension acts cooperatively with Wnt signalling to establish planar cell polarity. Development 2022; 149:275482. [PMID: 35593440 DOI: 10.1242/dev.200515] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 05/06/2022] [Indexed: 01/28/2023]
Abstract
Planar cell polarity (PCP) is the aligned cell polarity within a tissue plane. Mechanical signals are known to act as a global cue for PCP, yet their exact role is still unclear. In this study, we focused on PCP in the posterior neuroectoderm of Xenopus laevis and investigated how mechanical signals regulate polarity. We reveal that the neuroectoderm is under a greater tension in the anterior-posterior direction and that perturbation of this tension causes PCP disappearance. We show that application of uniaxial stretch to explant tissues can control the orientation of PCP and that cells sense the tissue stretch indirectly through a change in their shape, rather than directly through detection of anisotropic tension. Furthermore, we reveal that PCP is most strongly established when the orientation of tissue stretch coincides with that of diffusion of locally expressed Wnt ligands, suggesting a cooperative relationship between these two PCP regulators.
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Affiliation(s)
- Sayuki Hirano
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Yusuke Mii
- National Institute for Basic Biology and Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan.,Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan.,Department of Basic Biology, Graduate School for Advanced Studies (SOKENDAI), 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan.,Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Guillaume Charras
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK.,Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.,Institute for the Physics of Living Systems, University College London, Gower Street, London WC1E 6BT, UK
| | - Tatsuo Michiue
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
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4
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Assembly of protein complexes restricts diffusion of Wnt3a proteins. Commun Biol 2018; 1:165. [PMID: 30320232 PMCID: PMC6179999 DOI: 10.1038/s42003-018-0172-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
Members of the Wnt protein family play roles in many aspects of embryogenesis and homeostasis. Despite their biological significance, characteristics of Wnt proteins still remain unclear, mainly due to their insolubility after the removal of serum. Here we examine Wnt proteins in serum-containing media by using analytical ultracentrifugation with a fluorescence detection system. This analysis reveals that Wnt3a assembles into high-molecular-weight complexes that become dissociable by interaction with the extracellular domain of the Frizzled8 receptor or secreted Wnt-binding protein sFRP2. Cross-linking and single-particle analyses of Wnt3a fractionated by gel filtration chromatography show the homo-trimer to be the smallest form of the assembled Wnt3a complexes. Fluorescence correlation spectroscopy and immunohistochemistry reveal that the assembly of Wnt3a complexes restricted their diffusion and signaling range in Xenopus laevis embryos. Thus, we propose that the Wnt diffusion range can be controlled by a balance between the assembly of Wnt complexes and their dissociation. Ritsuko Takada et al. show that Wnt3a assembles into high molecular weight complexes that restrict the diffusion of Wnt within Xenopus embryos. These results suggest that Wnt diffusion in cells is controlled by a balance between higher order complex assembly and dissociation by Wnt-binding proteins.
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5
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Abstract
TGF-β family ligands function in inducing and patterning many tissues of the early vertebrate embryonic body plan. Nodal signaling is essential for the specification of mesendodermal tissues and the concurrent cellular movements of gastrulation. Bone morphogenetic protein (BMP) signaling patterns tissues along the dorsal-ventral axis and simultaneously directs the cell movements of convergence and extension. After gastrulation, a second wave of Nodal signaling breaks the symmetry between the left and right sides of the embryo. During these processes, elaborate regulatory feedback between TGF-β ligands and their antagonists direct the proper specification and patterning of embryonic tissues. In this review, we summarize the current knowledge of the function and regulation of TGF-β family signaling in these processes. Although we cover principles that are involved in the development of all vertebrate embryos, we focus specifically on three popular model organisms: the mouse Mus musculus, the African clawed frog of the genus Xenopus, and the zebrafish Danio rerio, highlighting the similarities and differences between these species.
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Affiliation(s)
- Joseph Zinski
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
| | - Benjamin Tajer
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
| | - Mary C Mullins
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
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6
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Satou Y, Minami K, Hosono E, Okada H, Yasuoka Y, Shibano T, Tanaka T, Taira M. Phosphorylation states change Otx2 activity for cell proliferation and patterning in the Xenopus embryo. Development 2018; 145:dev.159640. [PMID: 29440302 DOI: 10.1242/dev.159640] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 02/01/2018] [Indexed: 12/19/2022]
Abstract
The homeodomain transcription factor Otx2 has essential roles in head and eye formation via the negative and positive regulation of its target genes, but it remains elusive how this dual activity of Otx2 affects cellular functions. In the current study, we first demonstrated that both exogenous and endogenous Otx2 are phosphorylated at multiple sites. Using Xenopus embryos, we identified three possible cyclin-dependent kinase (Cdk) sites and one Akt site, and analyzed the biological activities of phosphomimetic (4E) and nonphosphorylatable (4A) mutants for those sites. In the neuroectoderm, the 4E but not the 4A mutant downregulated the Cdk inhibitor gene p27xic1 (cdknx) and posterior genes, and promoted cell proliferation, possibly forming a positive-feedback loop consisting of Cdk, Otx2 and p27xic1 for cell proliferation, together with anteriorization. Conversely, the 4A mutant functioned as an activator on its own and upregulated the expression of eye marker genes, resulting in enlarged eyes. Consistent with these results, the interaction of Otx2 with the corepressor Tle1 is suggested to be phosphorylation dependent. These data suggest that Otx2 orchestrates cell proliferation, anteroposterior patterning and eye formation via its phosphorylation state.
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Affiliation(s)
- Yumeko Satou
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kohei Minami
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Erina Hosono
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hajime Okada
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuuri Yasuoka
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.,Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
| | - Takashi Shibano
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Toshiaki Tanaka
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Masanori Taira
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
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7
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Abstract
The discovery of the transforming growth factor β (TGF-β) family ligands and the realization that their bioactivities need to be tightly controlled temporally and spatially led to intensive research that has identified a multitude of extracellular modulators of TGF-β family ligands, uncovered their functions in developmental and pathophysiological processes, defined the mechanisms of their activities, and explored potential modulator-based therapeutic applications in treating human diseases. These studies revealed a diverse repertoire of extracellular and membrane-associated molecules that are capable of modulating TGF-β family signals via control of ligand availability, processing, ligand-receptor interaction, and receptor activation. These molecules include not only soluble ligand-binding proteins that were conventionally considered as agonists and antagonists of TGF-β family of growth factors, but also extracellular matrix (ECM) proteins and proteoglycans that can serve as "sink" and control storage and release of both the TGF-β family ligands and their regulators. This extensive network of soluble and ECM modulators helps to ensure dynamic and cell-specific control of TGF-β family signals. This article reviews our knowledge of extracellular modulation of TGF-β growth factors by diverse proteins and their molecular mechanisms to regulate TGF-β family signaling.
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Affiliation(s)
- Chenbei Chang
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294
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8
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Brinkmann EM, Mattes B, Kumar R, Hagemann AIH, Gradl D, Scholpp S, Steinbeisser H, Kaufmann LT, Özbek S. Secreted Frizzled-related Protein 2 (sFRP2) Redirects Non-canonical Wnt Signaling from Fz7 to Ror2 during Vertebrate Gastrulation. J Biol Chem 2016; 291:13730-42. [PMID: 27129770 DOI: 10.1074/jbc.m116.733766] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Indexed: 02/04/2023] Open
Abstract
Convergent extension movements during vertebrate gastrulation require a balanced activity of non-canonical Wnt signaling pathways, but the factors regulating this interplay on the molecular level are poorly characterized. Here we show that sFRP2, a member of the secreted frizzled-related protein (sFRP) family, is required for morphogenesis and papc expression during Xenopus gastrulation. We further provide evidence that sFRP2 redirects non-canonical Wnt signaling from Frizzled 7 (Fz7) to the receptor tyrosine kinase-like orphan receptor 2 (Ror2). During this process, sFRP2 promotes Ror2 signal transduction by stabilizing Wnt5a-Ror2 complexes at the membrane, whereas it inhibits Fz7 signaling, probably by blocking Fz7 receptor endocytosis. The cysteine-rich domain of sFRP2 is sufficient for Ror2 activation, and related sFRPs can substitute for this function. Notably, direct interaction of the two receptors via their cysteine-rich domains also promotes Ror2-mediated papc expression but inhibits Fz7 signaling. We propose that sFRPs can act as a molecular switch, channeling the signal input for different non-canonical Wnt pathways during vertebrate gastrulation.
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Affiliation(s)
- Eva-Maria Brinkmann
- From the Institute of Human Genetics, Department of Developmental Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Benjamin Mattes
- the Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, 76344 Karlsruhe, Germany
| | - Rahul Kumar
- From the Institute of Human Genetics, Department of Developmental Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Anja I H Hagemann
- the Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, 76344 Karlsruhe, Germany
| | - Dietmar Gradl
- the Zoological Institute, Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany, and
| | - Steffen Scholpp
- the Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, 76344 Karlsruhe, Germany
| | - Herbert Steinbeisser
- From the Institute of Human Genetics, Department of Developmental Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Lilian T Kaufmann
- From the Institute of Human Genetics, Department of Developmental Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany,
| | - Suat Özbek
- the Centre of Organismal Studies, Department of Molecular Evolution and Genomics, University of Heidelberg, 69120 Heidelberg, Germany
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9
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Miyagi A, Negishi T, Yamamoto TS, Ueno N. G protein-coupled receptors Flop1 and Flop2 inhibit Wnt/β-catenin signaling and are essential for head formation in Xenopus. Dev Biol 2015; 407:131-44. [PMID: 26244992 DOI: 10.1016/j.ydbio.2015.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 06/18/2015] [Accepted: 08/01/2015] [Indexed: 12/11/2022]
Abstract
Patterning of the vertebrate anterior-posterior axis is regulated by the coordinated action of growth factors whose effects can be further modulated by upstream and downstream mediators and the cross-talk of different intracellular pathways. In particular, the inhibition of the Wnt/β-catenin signaling pathway by various factors is critically required for anterior specification. Here, we report that Flop1 and Flop2 (Flop1/2), G protein-coupled receptors related to Gpr4, contribute to the regulation of head formation by inhibiting Wnt/β-catenin signaling in Xenopus embryos. Using whole-mount in situ hybridization, we showed that flop1 and flop2 mRNAs were expressed in the neural ectoderm during early gastrulation. Both the overexpression and knockdown of Flop1/2 resulted in altered embryonic head phenotypes, while the overexpression of either Flop1/2 or the small GTPase RhoA in the absence of bone morphogenetic protein (BMP) signaling resulted in ectopic head induction. Examination of the Flops' function in Xenopus embryo animal cap cells showed that they inhibited Wnt/β-catenin signaling by promoting β-catenin degradation through both RhoA-dependent and -independent pathways in a cell-autonomous manner. These results suggest that Flop1 and Flop2 are essential regulators of Xenopus head formation that act as novel inhibitory components of the Wnt/β-catenin signaling pathway.
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Affiliation(s)
- Asuka Miyagi
- Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Takefumi Negishi
- Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Takamasa S Yamamoto
- Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Naoto Ueno
- Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan.
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10
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Abstract
The Wnt pathway is a major embryonic signaling pathway that controls cell proliferation, cell fate, and body-axis determination in vertebrate embryos. Soon after egg fertilization, Wnt pathway components play a role in microtubule-dependent dorsoventral axis specification. Later in embryogenesis, another conserved function of the pathway is to specify the anteroposterior axis. The dual role of Wnt signaling in Xenopus and zebrafish embryos is regulated at different developmental stages by distinct sets of Wnt target genes. This review highlights recent progress in the discrimination of different signaling branches and the identification of specific pathway targets during vertebrate axial development.
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Affiliation(s)
- Hiroki Hikasa
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
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11
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Ossipova O, Sokol SY. Neural crest specification by noncanonical Wnt signaling and PAR-1. Development 2012; 138:5441-50. [PMID: 22110058 DOI: 10.1242/dev.067280] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Neural crest (NC) cells are multipotent progenitors that form at the neural plate border, undergo epithelial-mesenchymal transition and migrate to diverse locations in vertebrate embryos to give rise to many cell types. Multiple signaling factors, including Wnt proteins, operate during early embryonic development to induce the NC cell fate. Whereas the requirement for the Wnt/β-catenin pathway in NC specification has been well established, a similar role for Wnt proteins that do not stabilize β-catenin has remained unclear. Our gain- and loss-of-function experiments implicate Wnt11-like proteins in NC specification in Xenopus embryos. In support of this conclusion, modulation of β-catenin-independent signaling through Dishevelled and Ror2 causes predictable changes in premigratory NC. Morpholino-mediated depletion experiments suggest that Wnt11R, a Wnt protein that is expressed in neuroectoderm adjacent to the NC territory, is required for NC formation. Wnt11-like signals might specify NC by altering the localization and activity of the serine/threonine polarity kinase PAR-1 (also known as microtubule-associated regulatory kinase or MARK), which itself plays an essential role in NC formation. Consistent with this model, PAR-1 RNA rescues NC markers in embryos in which noncanonical Wnt signaling has been blocked. These experiments identify novel roles for Wnt11R and PAR-1 in NC specification and reveal an unexpected connection between morphogenesis and cell fate.
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Affiliation(s)
- Olga Ossipova
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA
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12
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Kuraku S, Kuratani S. Genome-wide detection of gene extinction in early mammalian evolution. Genome Biol Evol 2011; 3:1449-62. [PMID: 22094861 PMCID: PMC3296468 DOI: 10.1093/gbe/evr120] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Detecting gene losses is a novel aspect of evolutionary genomics that has been made feasible by whole-genome sequencing. However, research to date has concentrated on elucidating evolutionary patterns of genomic components shared between species, rather than identifying disparities between genomes. In this study, we searched for gene losses in the lineage leading to eutherian mammals. First, as a pilot analysis, we selected five gene families (Wnt, Fgf, Tbx, TGFβ, and Frizzled) for molecular phylogenetic analyses, and identified mammalian lineage-specific losses of Wnt11b, Tbx6L/VegT/tbx16, Nodal-related, ADMP1, ADMP2, Sizzled, and Crescent. Second, automated genome-wide phylogenetic screening was implemented based on this pilot analysis. As a result, we detected 147 chicken genes without eutherian orthologs, which resulted from 141 gene loss events. Our inventory contained a group of regulatory genes governing early embryonic axis formation, such as Noggins, and multiple members of the opsin and prolactin-releasing hormone receptor (“PRLHR”) gene families. Our findings highlight the potential of genome-wide gene phylogeny (“phylome”) analysis in detecting possible rearrangement of gene networks and the importance of identifying losses of ancestral genomic components in analyzing the molecular basis underlying phenotypic evolution.
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Affiliation(s)
- Shigehiro Kuraku
- Laboratory for Evolutionary Morphology, RIKEN Center for Developmental Biology, Kobe, Japan.
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13
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Mii Y, Taira M. Secreted Wnt "inhibitors" are not just inhibitors: regulation of extracellular Wnt by secreted Frizzled-related proteins. Dev Growth Differ 2011; 53:911-23. [PMID: 21995331 DOI: 10.1111/j.1440-169x.2011.01299.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Gradient formation and signaling ranges of secreted proteins are crucial problems to understand how morphogens work for positional information and patterning in animal development. Yet, extracellular behaviors of secreted signaling molecules remain unexplored compared to their downstream pathways inside the cell. Recent advances in bioimaging make it possible to directly visualize morphogen molecules, and this simple strategy has, at least partly, succeeded in uncovering molecular behaviors of morphogens, such as Wnt (wingless-type MMTV integration site family member) and BMP (bone morphogenetic protein) as well as secreted Wnt binding proteins, sFRPs (secreted Frizzled-related proteins), in embryonic tissues. Here, we review the regulation of Wnt signaling by sFRPs, focusing on extracellular regulation of Wnt ligands in comparison with other morphogens. We also discuss evolutionary aspects with comprehensive syntenic and phylogenetic information about vertebrate sfrp genes. We newly annotated several sfrp genes including sfrp2-like 1 (sfrp2l1) in frogs and fishes and crescent in mammals.
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Affiliation(s)
- Yusuke Mii
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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14
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Dorsal-ventral patterning: Crescent is a dorsally secreted Frizzled-related protein that competitively inhibits Tolloid proteases. Dev Biol 2011; 352:317-28. [PMID: 21295563 DOI: 10.1016/j.ydbio.2011.01.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 01/25/2011] [Accepted: 01/26/2011] [Indexed: 11/20/2022]
Abstract
In Xenopus, dorsal-ventral (D-V) patterning can self-regulate after embryo bisection. This is mediated by an extracellular network of proteins secreted by the dorsal and ventral centers of the gastrula. Different proteins of similar activity can be secreted at these two poles, but under opposite transcriptional control. Here we show that Crescent, a dorsal protein, can compensate for the loss of Sizzled, a ventral protein. Crescent is a secreted Frizzled-Related Protein (sFRP) known to regulate Wnt8 and Wnt11 activity. We now find that Crescent also regulates the BMP pathway. Crescent expression was increased by the BMP antagonist Chordin and repressed by BMP4, while the opposite was true for Sizzled. Crescent knock-down increased the expression of BMP target genes, and synergized with Sizzled morpholinos. Thus, Crescent loss-of-function is compensated by increased expression of its ventral counterpart Sizzled. Crescent overexpression dorsalized whole embryos but not ventral half-embryos, indicating that Crescent requires a dorsal component to exert its anti-BMP activity. Crescent protein lost its dorsalizing activity in Chordin-depleted embryos. When co-injected, Crescent and Chordin proteins greatly synergized in the dorsalization of Xenopus embryos. The molecular mechanism of these phenotypes is explained by the ability of Crescent to inhibit Tolloid metalloproteinases, which normally degrade Chordin. Enzyme kinetic studies showed that Crescent was a competitive inhibitor of Tolloid activity, which bound to Tolloid/BMP1 with a K(D) of 11 nM. In sum, Crescent is a new component of the D-V pathway, which functions as the dorsal counterpart of Sizzled, through the regulation of chordinases of the Tolloid family.
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15
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Mii Y, Taira M. Secreted Frizzled-related proteins enhance the diffusion of Wnt ligands and expand their signalling range. Development 2009; 136:4083-8. [PMID: 19906850 DOI: 10.1242/dev.032524] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Secreted Frizzled-related proteins (sFRPs) are thought to negatively modulate Wnt signalling. Although Wnt proteins are thought to diffuse extracellularly and act as morphogens, little is known about the diffusibility of either Wnts or sFRPs. Here we show that Frzb and Crescent (Cres), which are members of the sFRP family, have the ability to regulate the diffusibility and signalling areas of the Wnt ligands Wnt8 and Wnt11. We found, using the Xenopus embryo, that Wnts do not diffuse effectively, whereas Frzb and Cres spread very widely. Interestingly, Frzb and Cres substantially promoted the diffusion of Wnt8 and Wnt11 through extracellular interactions. Importantly, we show that Wnt8 conveyed by sFRPs can activate canonical Wnt signalling despite the function of sFRPs as Wnt inhibitors, suggesting a novel regulatory system for Wnts by sFRPs.
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Affiliation(s)
- Yusuke Mii
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
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16
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Kim H, Cheong SM, Ryu J, Jung HJ, Jho EH, Han JK. Xenopus Wntless and the retromer complex cooperate to regulate XWnt4 secretion. Mol Cell Biol 2009; 29:2118-28. [PMID: 19223472 PMCID: PMC2663306 DOI: 10.1128/mcb.01503-08] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 10/27/2008] [Accepted: 02/02/2009] [Indexed: 11/20/2022] Open
Abstract
Wnt signaling is implicated in a variety of developmental and pathological processes. The molecular mechanisms governing the secretion of Wnt ligands remain to be elucidated. Wntless, an evolutionarily conserved multipass transmembrane protein, is a dedicated secretion factor of Wnt proteins that participates in Drosophila melanogaster embryogenesis. In this study, we show that Xenopus laevis Wntless (XWntless) regulates the secretion of a specific Wnt ligand, XWnt4, and that this regulation is specifically required for eye development in Xenopus. Moreover, the Retromer complex is required for XWntless recycling to regulate the XWnt4-mediated eye development. Inhibition of Retromer function by Vps35 morpholino (MO) resulted in various Wnt deficiency phenotypes, affecting mesoderm induction, gastrulation cell movements, neural induction, neural tube closure, and eye development. Overexpression of XWntless led to the rescue of Vps35 MO-mediated eye defects but not other deficiencies. These results collectively suggest that XWntless and the Retromer complex are required for the efficient secretion of XWnt4, facilitating its role in Xenopus eye development.
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Affiliation(s)
- Hyunjoon Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Republic of Korea
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Dickinson AJG, Sive HL. The Wnt antagonists Frzb-1 and Crescent locally regulate basement membrane dissolution in the developing primary mouth. Development 2009; 136:1071-81. [PMID: 19224982 DOI: 10.1242/dev.032912] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The primary mouth forms from ectoderm and endoderm at the extreme anterior of the embryo, a conserved mesoderm-free region. In Xenopus, a very early step in primary mouth formation is loss of the basement membrane between the ectoderm and endoderm. In an unbiased microarray screen, we defined genes encoding the sFRPs Frzb-1 and Crescent as transiently and locally expressed in the primary mouth anlage. Using antisense oligonucleotides and ;face transplants', we show that frzb-1 and crescent expression is specifically required in the primary mouth region at the time this organ begins to form. Several assays indicate that Frzb-1 and Crescent modulate primary mouth formation by suppressing Wnt signaling, which is likely to be mediated by beta-catenin. First, a similar phenotype (no primary mouth) is seen after loss of Frzb-1/Crescent function to that seen after temporally and spatially restricted overexpression of Wnt-8. Second, overexpression of either Frzb-1 or Dkk-1 results in an enlarged primary mouth anlage. Third, overexpression of Dkk-1 can restore a primary mouth to embryos in which Frzb-1/Crescent expression has been inhibited. We show that Frzb-1/Crescent function locally promotes basement membrane dissolution in the primary mouth primordium. Consistently, Frzb-1 overexpression decreases RNA levels of the essential basement membrane genes fibronectin and laminin, whereas Wnt-8 overexpression increases the levels of these RNAs. These data are the first to connect Wnt signaling and basement membrane integrity during primary mouth development, and suggest a general paradigm for the regulation of basement membrane remodeling.
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Involvement of an inner nuclear membrane protein, Nemp1, in Xenopus neural development through an interaction with the chromatin protein BAF. Dev Biol 2009; 327:497-507. [PMID: 19167377 DOI: 10.1016/j.ydbio.2008.12.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 12/22/2008] [Accepted: 12/23/2008] [Indexed: 11/20/2022]
Abstract
To clarify the molecular mechanisms of neural development in vertebrates, we analyzed a novel gene, termed nemp1 (nuclear envelope integral membrane protein 1), which is expressed in the Xenopus anterior neuroectoderm at the neurula stage. Nemp1 has a putative signal peptide and five transmembrane domains, but does not have any other known domains. We show that Nemp1 is localized to the inner nuclear membrane (INM) with its evolutionarily conserved C-terminal region facing the nucleoplasm. Both overexpression and knockdown of Nemp1 in Xenopus embryos reduced the expression of early eye marker genes, rax, tbx3, and pax6, and later resulted mainly in severe eye defects at the tailbud stage. In contrast, the expression of a forebrain/midbrain marker, otx2, and a pan-neural marker, sox2, was largely unaffected. Deletion analysis of Nemp1 showed that nuclear envelope-localization of the C-terminal region is necessary for its eye-reducing activity. Furthermore, nemp1 is coexpressed with baf (barrier-to-autointegration factor) in the eye anlagen, and that Nemp1 interacts with BAF through the BAF-binding site in the C-terminal region and this site is required for Nemp1 activity. These data suggest that Nemp1 is involved in the expression of eye marker genes by functioning at the INM at least partly through BAF.
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Saito Y, Gotoh M, Ujiie Y, Izutsu Y, Maéno M. Involvement of AP-2rep in morphogenesis of the axial mesoderm in Xenopus embryo. Cell Tissue Res 2008; 335:357-69. [PMID: 19048294 DOI: 10.1007/s00441-008-0712-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 09/24/2008] [Indexed: 11/27/2022]
Abstract
We have previously isolated a cDNA clone coding for Xenopus AP-2rep (activator protein-2 repressor), a member of the Krüppel-like factor family, and reported its expression pattern in developing Xenopus embryos. In the present study, the physiological function of AP-2rep in the morphogenetic movements of the dorsal mesoderm and ectoderm was investigated. Embryos injected with either AP-2rep or VP16repC (a dominant-negative mutant) into the dorsal marginal zone at the 4-cell stage exhibited abnormal morphology in dorsal structures. Both AP-2rep and VP16repC also inhibited the elongation of animal cap explants treated with activin without affecting the expression of differentiation markers. Whole-mount in situ hybridization analysis revealed that expression of brachyury and Wnt11 was greatly suppressed by injection of VP16repC or AP-2rep morpholino, but expression was restored by the simultaneous injection of wild-type AP-2rep RNA. Furthermore, the morphogenetic abnormality induced by injection of VP16repC or AP-2rep morpholino was restored by simultaneous injection of brachyury or Wnt11 mRNA. These results show that AP-2rep is involved in the morphogenesis of the mesoderm at the gastrula stage, via the brachyury and/or Wnt pathways.
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Affiliation(s)
- Yoshinari Saito
- Graduate School of Science and Technology, Niigata University, Nishi-ku, Niigata, Japan
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Bovolenta P, Esteve P, Ruiz JM, Cisneros E, Lopez-Rios J. Beyond Wnt inhibition: new functions of secreted Frizzled-related proteins in development and disease. J Cell Sci 2008; 121:737-46. [PMID: 18322270 DOI: 10.1242/jcs.026096] [Citation(s) in RCA: 478] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The secreted Frizzled-related proteins (SFRPs) are a family of soluble proteins that are structurally related to Frizzled (Fz) proteins, the serpentine receptors that mediate the extensively used cell-cell communication pathway involving Wnt signalling. Because of their homology with the Wnt-binding domain on the Fz receptors, SFRPs were immediately characterised as antagonists that bind to Wnt proteins to prevent signal activation. Since these initial studies, interest in the family of SFRPs has grown progressively, offering new perspectives on their function and mechanism of action in both development and disease. These studies indicate that SFRPs are not merely Wnt-binding proteins, but can also antagonise one another's activity, bind to Fz receptors and influence axon guidance, interfere with BMP signalling by acting as proteinase inhibitors, and interact with other receptors or matrix molecules. Furthermore, their expression is altered in different types of cancers, bone pathologies, retinal degeneration and hypophosphatemic diseases, indicating that their activity is fundamental for tissue homeostasis. Here we review some of the debated aspects of SFRP-Wnt interactions and discuss the new and emerging roles of SFRPs.
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Affiliation(s)
- Paola Bovolenta
- Departamento de Neurobiología Molecular, Celular y del Desarrollo, Instituto Cajal, CSIC, Dr Arce 37, Madrid 28002, Spain.
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Luyten A, Mortier E, Van Campenhout C, Taelman V, Degeest G, Wuytens G, Lambaerts K, David G, Bellefroid EJ, Zimmermann P. The postsynaptic density 95/disc-large/zona occludens protein syntenin directly interacts with frizzled 7 and supports noncanonical Wnt signaling. Mol Biol Cell 2008; 19:1594-604. [PMID: 18256285 DOI: 10.1091/mbc.e07-08-0832] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Wnt signaling pathways are essential for embryonic patterning, and they are disturbed in a wide spectrum of diseases, including cancer. An unresolved question is how the different Wnt pathways are supported and regulated. We previously established that the postsynaptic density 95/disc-large/zona occludens (PDZ) protein syntenin binds to syndecans, Wnt coreceptors, and known stimulators of protein kinase C (PKC)alpha and CDC42 activity. Here, we show that syntenin also interacts with the C-terminal PDZ binding motif of several Frizzled Wnt receptors, without compromising the recruitment of Dishevelled, a key downstream Wnt-signaling component. Syntenin is coexpressed with cognate Frizzled during early development in Xenopus. Overexpression and down-regulation of syntenin disrupt convergent extension movements, supporting a role for syntenin in noncanonical Wnt signaling. Syntenin stimulates c-jun phosphorylation and modulates Frizzled 7 signaling, in particular the PKCalpha/CDC42 noncanonical Wnt signaling cascade. The syntenin-Frizzled 7 binding mode indicates syntenin can accommodate Frizzled 7-syndecan complexes. We propose that syntenin is a novel component of the Wnt signal transduction cascade and that it might function as a direct intracellular link between Frizzled and syndecans.
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Affiliation(s)
- Annouck Luyten
- Department of Human Genetics, K.U. Leuven, B-3000 Leuven, Belgium
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