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Tophkhane SS, Fu K, Verheyen EM, Richman JM. Craniofacial studies in chicken embryos confirm the pathogenicity of human FZD2 variants associated with Robinow syndrome. Dis Model Mech 2024; 17:dmm050584. [PMID: 38967226 PMCID: PMC11247504 DOI: 10.1242/dmm.050584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 05/16/2024] [Indexed: 07/06/2024] Open
Abstract
Robinow syndrome is a rare disease caused by variants of seven WNT pathway genes. Craniofacial features include widening of the nasal bridge and jaw hypoplasia. We used the chicken embryo to test whether two missense human FZD2 variants (1301G>T, p.Gly434Val; 425C>T, p.Pro142Lys) were sufficient to change frontonasal mass development. In vivo, the overexpression of retroviruses with wild-type or variant human FZD2 inhibited upper beak ossification. In primary cultures, wild-type and variant human FZD2 significantly inhibited chondrogenesis, with the 425C>T variant significantly decreasing activity of a SOX9 luciferase reporter compared to that for the wild type or 1301G>T. Both variants also increased nuclear shuttling of β-catenin (CTNNB1) and increased the expression of TWIST1, which are inhibitory to chondrogenesis. In canonical WNT luciferase assays using frontonasal mass cells, the variants had dominant-negative effects on wild-type FZD2. In non-canonical assays, the 425C>T variant failed to activate the reporter above control levels and was unresponsive to exogenous WNT5A. This is the first single amino acid change to selectively alter ligand binding in a FZD receptor. Therefore, FZD2 missense variants are pathogenic and could lead to the altered craniofacial morphogenesis seen in Robinow syndrome.
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Affiliation(s)
- Shruti S. Tophkhane
- Life Sciences Institute and Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Katherine Fu
- Life Sciences Institute and Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Esther M. Verheyen
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Joy M. Richman
- Life Sciences Institute and Faculty of Dentistry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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2
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Asada N, Suzuki K, Sunohara M. Spatiotemporal distribution analyses of Wnt5a ligand and its receptors Ror2, Frizzled2, and Frizzled5 during tongue muscle development in prenatal mice. Ann Anat 2022; 245:152017. [DOI: 10.1016/j.aanat.2022.152017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/22/2022] [Accepted: 09/30/2022] [Indexed: 11/05/2022]
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3
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Shao J, Liu Y, Zhao S, Sun W, Zhan J, Cao L. A novel variant in the ROR2 gene underlying brachydactyly type B: a case report. BMC Pediatr 2022; 22:528. [PMID: 36064339 PMCID: PMC9446770 DOI: 10.1186/s12887-022-03564-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
Background Brachydactyly type B is an autosomal dominant disorder that is characterized by hypoplasia of the distal phalanges and nails and can be divided into brachydactyly type B1 (BDB1) and brachydactyly type B2 (BDB2). BDB1 is the most severe form of brachydactyly and is caused by truncating variants in the receptor tyrosine kinase–like orphan receptor 2 (ROR2) gene. Case presentation Here, we report a five-generation Chinese family with brachydactyly with or without syndactyly. The proband and her mother underwent digital separation in syndactyly, and the genetic analyses of the proband and her parents were provided. The novel heterozygous frameshift variant c.1320dupG, p.(Arg441Alafs*18) in the ROR2 gene was identified in the affected individuals by whole-exome sequencing and Sanger sequencing. The c.1320dupG variant in ROR2 is predicted to produce a truncated protein that lacks tyrosine kinase and serine/threonine- and proline-rich structures and remarkably alters the tertiary structures of the mutant ROR2 protein. Conclusion The c.1320dupG, p.(Arg441Alafs*18) variant in the ROR2 gene has not been reported in any databases thus far and therefore is novel. Our study extends the gene variant spectrum of brachydactyly and may provide information for the genetic counselling of family members. Supplementary Information The online version contains supplementary material available at 10.1186/s12887-022-03564-z.
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Affiliation(s)
- Jiaqi Shao
- College of Kinesiology, Shenyang Sport University, No. 36 Jinqiansong East Road, Sujiatun District, Shenyang, 110102, China
| | - Yue Liu
- Hand SurgeryCentral Hospital Affiliated to Shenyang Medical CollegeTiexi District, Dept.4No. 5 Nanqi West Road, Shenyang, 110024, China
| | - Shuyang Zhao
- College of Kinesiology, Shenyang Sport University, No. 36 Jinqiansong East Road, Sujiatun District, Shenyang, 110102, China
| | - Weisheng Sun
- College of Kinesiology, Shenyang Sport University, No. 36 Jinqiansong East Road, Sujiatun District, Shenyang, 110102, China
| | - Jie Zhan
- Hand SurgeryCentral Hospital Affiliated to Shenyang Medical CollegeTiexi District, Dept.4No. 5 Nanqi West Road, Shenyang, 110024, China.
| | - Lihua Cao
- College of Kinesiology, Shenyang Sport University, No. 36 Jinqiansong East Road, Sujiatun District, Shenyang, 110102, China.
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4
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Guo R, Xing QS. Roles of Wnt Signaling Pathway and ROR2 Receptor in Embryonic Development: An Update Review Article. Epigenet Insights 2022; 15:25168657211064232. [PMID: 35128307 PMCID: PMC8808015 DOI: 10.1177/25168657211064232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 11/15/2021] [Indexed: 11/15/2022] Open
Abstract
The Wnt family is a large class of highly conserved cysteine-rich secretory glycoproteins that play a vital role in various cellular and physiological courses through different signaling pathways during embryogenesis and tissue homeostasis 3. Wnt5a is a secreted glycoprotein that belongs to the noncanonical Wnt family and is involved in a wide range of developmental and tissue homeostasis. A growing body of evidence suggests that Wnt5a affects embryonic development, signaling through various receptors, starting with the activation of β-catenin by Wnt5a. In addition to affecting planar cell polarity and Ca2+ pathways, β-catenin also includes multiple signaling cascades that regulate various cell functions. Secondly, Wnt5a can bind to Ror receptors to mediate noncanonical Wnt signaling and a significant ligand for Ror2 in vertebrates. Consistent with the multiple functions of Wnt5A/Ror2 signaling, Wnt5A knockout mice exhibited various phenotypic defects, including an inability to extend the anterior and posterior axes of the embryo. Numerous essential roles of Wnt5a/Ror2 in development have been demonstrated. Therefore, Ror signaling pathway become a necessary target for diagnosing and treating human diseases. The Wnt5a- Ror2 signaling pathway as a critical factor has attracted extensive attention.
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Affiliation(s)
- Rui Guo
- Qingdao University, Qingdao, China
| | - Quan Sheng Xing
- Qingdao University-Affiliated Hospital of Women and Children, Qingdao, China
- Quan Sheng Xing, Qingdao University-Affiliated Hospital of Women and Children, tongfu road 6, shibei district, Qingdao 266000, China.
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Zhao Y, Zhang D, Guo Y, Lu B, Zhao ZJ, Xu X, Chen Y. Tyrosine Kinase ROR1 as a Target for Anti-Cancer Therapies. Front Oncol 2021; 11:680834. [PMID: 34123850 PMCID: PMC8193947 DOI: 10.3389/fonc.2021.680834] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 04/29/2021] [Indexed: 12/15/2022] Open
Abstract
Receptor tyrosine kinase ROR1 plays an essential role in embryogenesis and is overexpressed in many types of malignant tumors. Studies have demonstrated that it plays an important role in oncogenesis by activating cell survival signaling events, particularly the non-canonical WNT signaling pathway. Antibody-based immunotherapies targeting ROR1 have been developed and evaluated in preclinical and clinical studies with promising outcomes. However, small molecule inhibitors targeting ROR1 are underappreciated because of the initial characterization of ROR1 as a peusdokinase. The function of ROR1 as a tyrosine kinase remains poorly understood, although accumulating evidence have demonstrated its intrinsic tyrosine kinase activity. In this review, we analyzed the structural and functional features of ROR1 and discussed therapeutic strategies targeting this kinase.
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Affiliation(s)
- Yuming Zhao
- Edmond H. Fischer Translational Medical Research Laboratory, Scientific Research Center, The Seventh Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
| | - Dengyang Zhang
- Edmond H. Fischer Translational Medical Research Laboratory, Scientific Research Center, The Seventh Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
| | - Yao Guo
- Edmond H. Fischer Translational Medical Research Laboratory, Scientific Research Center, The Seventh Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
| | - Bo Lu
- Department of Hematology, The Seventh Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
| | - Zhizhuang Joe Zhao
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Xiaojun Xu
- Department of Hematology, The Seventh Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
| | - Yun Chen
- Edmond H. Fischer Translational Medical Research Laboratory, Scientific Research Center, The Seventh Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
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Puzik K, Tonnier V, Opper I, Eckert A, Zhou L, Kratzer MC, Noble FL, Nienhaus GU, Gradl D. Lef1 regulates caveolin expression and caveolin dependent endocytosis, a process necessary for Wnt5a/Ror2 signaling during Xenopus gastrulation. Sci Rep 2019; 9:15645. [PMID: 31666627 PMCID: PMC6821757 DOI: 10.1038/s41598-019-52218-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 10/10/2019] [Indexed: 11/09/2022] Open
Abstract
The activation of distinct branches of the Wnt signaling network is essential for regulating early vertebrate development. Activation of the canonical Wnt/β-catenin pathway stimulates expression of β-catenin-Lef/Tcf regulated Wnt target genes and a regulatory network giving rise to the formation of the Spemann organizer. Non-canonical pathways, by contrast, mainly regulate cell polarization and migration, in particular convergent extension movements of the trunk mesoderm during gastrulation. By transcriptome analyses, we found caveolin1, caveolin3 and cavin1 to be regulated by Lef1 in the involuting mesoderm of Xenopus embryos at gastrula stages. We show that caveolins and caveolin dependent endocytosis are necessary for proper gastrulation, most likely by interfering with Wnt5a/Ror2 signaling. Wnt5a regulates the subcellular localization of receptor complexes, including Ror2 homodimers, Ror2/Fzd7 and Ror2/dsh heterodimers in an endocytosis dependent manner. Live-cell imaging revealed endocytosis of Ror2/caveolin1 complexes. In Xenopus explants, in the presence of Wnt5a, these receptor clusters remain stable exclusively at the basolateral side, suggesting that endocytosis of non-canonical Wnt/receptor complexes preferentially takes place at the apical membrane. In support of this blocking endocytosis with inhibitors prevents the effects of Wnt5a. Thus, target genes of Lef1 interfere with Wnt5a/Ror2 signaling to coordinate gastrulation movements.
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Affiliation(s)
- Katharina Puzik
- Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Veronika Tonnier
- Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Isabell Opper
- Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Antonia Eckert
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Lu Zhou
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Marie-Claire Kratzer
- Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
| | - Ferdinand le Noble
- Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Dietmar Gradl
- Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany.
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7
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Mattes B, Dang Y, Greicius G, Kaufmann LT, Prunsche B, Rosenbauer J, Stegmaier J, Mikut R, Özbek S, Nienhaus GU, Schug A, Virshup DM, Scholpp S. Wnt/PCP controls spreading of Wnt/β-catenin signals by cytonemes in vertebrates. eLife 2018; 7:36953. [PMID: 30060804 PMCID: PMC6086664 DOI: 10.7554/elife.36953] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 07/16/2018] [Indexed: 12/31/2022] Open
Abstract
Signaling filopodia, termed cytonemes, are dynamic actin-based membrane structures that regulate the exchange of signaling molecules and their receptors within tissues. However, how cytoneme formation is regulated remains unclear. Here, we show that Wnt/planar cell polarity (PCP) autocrine signaling controls the emergence of cytonemes, and that cytonemes subsequently control paracrine Wnt/β-catenin signal activation. Upon binding of the Wnt family member Wnt8a, the receptor tyrosine kinase Ror2 becomes activated. Ror2/PCP signaling leads to the induction of cytonemes, which mediate the transport of Wnt8a to neighboring cells. In the Wnt-receiving cells, Wnt8a on cytonemes triggers Wnt/β-catenin-dependent gene transcription and proliferation. We show that cytoneme-based Wnt transport operates in diverse processes, including zebrafish development, murine intestinal crypt and human cancer organoids, demonstrating that Wnt transport by cytonemes and its control via the Ror2 pathway is highly conserved in vertebrates. Communication helps the cells that make up tissues and organs to work together as a team. One way that cells share information with each other as tissues grow and develop is by exchanging signaling proteins. These interact with receptors on the surface of other cells; this causes the cell to change how it behaves. The Wnt family of signaling proteins orchestrate organ development. Wnt proteins influence which types of cells develop, how fast they divide, and how and when they move. Relatively few cells, or small groups of cells, in developing tissues produce Wnt proteins, while larger groups nearby respond to the signals. We do not fully understand how Wnt proteins travel between cells, but recent work revealed an unexpected mechanism – cells seem to hand-deliver their messages. Finger-like structures called cytonemes grow out of the cell membrane and carry Wnt proteins to their destination. If the cytonemes do not form properly the target cells do not behave correctly, which can lead to severe tissue malformation. Mattes et al. have now investigated how cytonemes form using a combination of state-of-the-art genetic and high-resolution imaging techniques. In initial experiments involving zebrafish cells that were grown in the laboratory, Mattes et al. found that the Wnt proteins kick start their own transport; before they travel to their destination, they act on the cells that made them. A Wnt protein called Wnt8a activates the receptor Ror2 on the surface of the signal-producing cell. Ror2 then triggers signals inside the cell that begin the assembly of the cytonemes. The more Ror2 is activated, the more cytonemes the cell makes, and the more Wnt signals it can send out. This mechanism operates in various tissues: Ror2 also controls the cytoneme transport process in living zebrafish embryos, the mouse intestine and human stomach tumors. This knowledge will help researchers to develop new ways to control Wnt signaling, which could help to produce new treatments for diseases ranging from cancers (for example in the stomach and bowel) to degenerative diseases such as Alzheimer’s disease.
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Affiliation(s)
- Benjamin Mattes
- Living Systems Institute, School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Yonglong Dang
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gediminas Greicius
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | | | - Benedikt Prunsche
- Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Jakob Rosenbauer
- John von Neumann Institute for Computing, Jülich Supercomputing Centre, Jülich, Germany
| | - Johannes Stegmaier
- Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
| | - Ralf Mikut
- Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Suat Özbek
- Centre of Organismal Studies, University of Heidelberg, Karlsruhe, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Applied Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Alexander Schug
- John von Neumann Institute for Computing, Jülich Supercomputing Centre, Jülich, Germany.,Steinbuch Centre for Computing, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - David M Virshup
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | - Steffen Scholpp
- Living Systems Institute, School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
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8
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Roy JP, Halford MM, Stacker SA. The biochemistry, signalling and disease relevance of RYK and other WNT-binding receptor tyrosine kinases. Growth Factors 2018; 36:15-40. [PMID: 29806777 DOI: 10.1080/08977194.2018.1472089] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The receptor tyrosine kinases (RTKs) are a well-characterized family of growth factor receptors that have central roles in human disease and are frequently therapeutically targeted. The RYK, ROR, PTK7 and MuSK subfamilies make up an understudied subset of WNT-binding RTKs. Numerous developmental, stem cell and pathological roles of WNTs, in particular WNT5A, involve signalling via these WNT receptors. The WNT-binding RTKs have highly context-dependent signalling outputs and stimulate the β-catenin-dependent, planar cell polarity and/or WNT/Ca2+ pathways. RYK, ROR and PTK7 members have a pseudokinase domain in their intracellular regions. Alternative signalling mechanisms, including proteolytic cleavage and protein scaffolding functions, have been identified for these receptors. This review explores the structure, signalling, physiological and pathological roles of RYK, with particular attention paid to cancer and the possibility of therapeutically targeting RYK. The other WNT-binding RTKs are compared with RYK throughout to highlight the similarities and differences within this subset of WNT receptors.
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Affiliation(s)
- James P Roy
- a Tumour Angiogenesis and Microenvironment Program , Peter MacCallum Cancer Centre , Melbourne , Australia
- b Sir Peter MacCallum Department of Oncology , The University of Melbourne , Parkville , Australia
| | - Michael M Halford
- a Tumour Angiogenesis and Microenvironment Program , Peter MacCallum Cancer Centre , Melbourne , Australia
| | - Steven A Stacker
- a Tumour Angiogenesis and Microenvironment Program , Peter MacCallum Cancer Centre , Melbourne , Australia
- b Sir Peter MacCallum Department of Oncology , The University of Melbourne , Parkville , Australia
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9
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Schille C, Schambony A. Signaling pathways and tissue interactions in neural plate border formation. NEUROGENESIS 2017; 4:e1292783. [PMID: 28352644 DOI: 10.1080/23262133.2017.1292783] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/02/2017] [Accepted: 02/02/2017] [Indexed: 02/04/2023]
Abstract
The neural crest is a transient cell population that gives rise to various cell types of multiple tissues and organs in the vertebrate embryo. Neural crest cells arise from the neural plate border, a region localized at the lateral borders of the prospective neural plate. Temporally and spatially coordinated interaction with the adjacent tissues, the non-neural ectoderm, the neural plate and the prospective dorsolateral mesoderm, is required for neural plate border specification. Signaling molecules, namely BMP, Wnt and FGF ligands and corresponding antagonists are derived from these tissues and interact to induce the expression of neural plate border specific genes. The present mini-review focuses on the current understanding of how the NPB territory is formed and accentuates the need for coordinated interaction of BMP and Wnt signaling pathways and precise tissue communication that are required for the definition of the prospective NC in the competent ectoderm.
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Affiliation(s)
- Carolin Schille
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg , Erlangen, Germany
| | - Alexandra Schambony
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg , Erlangen, Germany
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10
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Abstract
ROR-family receptor tyrosine kinases form a small subfamily of receptor tyrosine kinases (RTKs), characterized by a conserved, unique domain architecture. ROR RTKs are evolutionary conserved throughout the animal kingdom and act as alternative receptors and coreceptors of WNT ligands. The intracellular signaling cascades activated downstream of ROR receptors are diverse, including but not limited to ROR-Frizzled-mediated activation of planar cell polarity signaling, RTK-like signaling, and antagonistic regulation of WNT/β-Catenin signaling. In line with their diverse repertoire of signaling functions, ROR receptors are involved in the regulation of multiple processes in embryonic development such as development of the axial and paraxial mesoderm, the nervous system and the neural crest, the axial and appendicular skeleton, and the kidney. In humans, mutations in the ROR2 gene cause two distinct developmental syndromes, recessive Robinow syndrome (RRS; MIM 268310) and dominant brachydactyly type B1 (BDB1; MIM 113000). In Robinow syndrome patients and animal models, the development of multiple organs is affected, whereas BDB1 results only in shortening of the distal phalanges of fingers and toes, reflecting the diversity of functions and signaling activities of ROR-family RTKs. In this chapter, we give an overview on ROR receptor structure and function. We discuss their signaling functions and role in vertebrate embryonic development with a focus on those developmental processes that are affected by mutations in the ROR2 gene in human patients.
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11
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Schille C, Bayerlová M, Bleckmann A, Schambony A. Ror2 signaling is required for local upregulation of GDF6 and activation of BMP signaling at the neural plate border. Development 2016; 143:3182-94. [DOI: 10.1242/dev.135426] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 07/25/2016] [Indexed: 12/31/2022]
Abstract
The receptor tyrosine kinase Ror2 is a major Wnt receptor that activates β-catenin-independent signaling and plays a conserved role in the regulation of convergent extension movements and planar cell polarity in vertebrates. Mutations in the ROR2 gene cause recessive Robinow syndrome in humans, a short-limbed dwarfism associated with craniofacial malformations. Here, we show that Ror2 is required for local upregulation of gdf6 at the neural plate border in Xenopus embryos. Ror2 morphant embryos fail to upregulate neural plate border genes and show defects in the induction of neural crest cell fate. These embryos lack the spatially restricted activation of BMP signaling at the neural plate border at early neurula stages, which is required for neural crest induction. Ror2-dependent planar cell polarity signaling is required in the dorsolateral marginal zone during gastrulation indirectly to upregulate the BMP ligand Gdf6 at the neural plate border and Gdf6 is sufficient to rescue neural plate border specification in Ror2 morphant embryos. Thereby, Ror2 links Wnt/planar cell polarity signaling to BMP signaling in neural plate border specification and neural crest induction.
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Affiliation(s)
- Carolin Schille
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen 91058, Germany
| | - Michaela Bayerlová
- Department of Medical Statistics, University Medical Center Göttingen, Göttingen 37073, Germany
| | - Annalen Bleckmann
- Department of Medical Statistics, University Medical Center Göttingen, Göttingen 37073, Germany
- Department of Hematology/Medical Oncology, University Medical Center Göttingen, Göttingen 37099, Germany
| | - Alexandra Schambony
- Biology Department, Developmental Biology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen 91058, Germany
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12
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Podleschny M, Grund A, Berger H, Rollwitz E, Borchers A. A PTK7/Ror2 Co-Receptor Complex Affects Xenopus Neural Crest Migration. PLoS One 2015; 10:e0145169. [PMID: 26680417 PMCID: PMC4683079 DOI: 10.1371/journal.pone.0145169] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 11/30/2015] [Indexed: 12/15/2022] Open
Abstract
Neural crest cells are a highly migratory pluripotent cell population that generates a wide array of different cell types and failure in their migration can result in severe birth defects and malformation syndromes. Neural crest migration is controlled by various means including chemotaxis, repellent guidance cues and cell-cell interaction. Non-canonical Wnt PCP (planar cell polarity) signaling has previously been shown to control cell-contact mediated neural crest cell guidance. PTK7 (protein tyrosine kinase 7) is a transmembrane pseudokinase and a known regulator of Wnt/PCP signaling, which is expressed in Xenopus neural crest cells and required for their migration. PTK7 functions as a Wnt co-receptor; however, it remains unclear by which means PTK7 affects neural crest migration. Expressing fluorescently labeled proteins in Xenopus neural crest cells we find that PTK7 co-localizes with the Ror2 Wnt-receptor. Further, co-immunoprecipitation experiments demonstrate that PTK7 interacts with Ror2. The PTK7/Ror2 interaction is likely relevant for neural crest migration, because Ror2 expression can rescue the PTK7 loss of function migration defect. Live cell imaging of explanted neural crest cells shows that PTK7 loss of function affects the formation of cell protrusions as well as cell motility. Co-expression of Ror2 can rescue these defects. In vivo analysis demonstrates that a kinase dead Ror2 mutant cannot rescue PTK7 loss of function. Thus, our data suggest that Ror2 can substitute for PTK7 and that the signaling function of its kinase domain is required for this effect.
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Affiliation(s)
- Martina Podleschny
- Faculty of Biology, Molecular Embryology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Anita Grund
- Faculty of Biology, Molecular Embryology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Hanna Berger
- Faculty of Biology, Molecular Embryology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Erik Rollwitz
- Faculty of Biology, Molecular Embryology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Annette Borchers
- Faculty of Biology, Molecular Embryology, Philipps-Universität Marburg, 35043 Marburg, Germany
- * E-mail:
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Abstract
Ror2 is a signaling receptor for Wnt ligands that is known to play important roles in limb development, but having no essential roles known in adult tissues. Recent evidence has implicated Ror2 in mediating both canonical and non-canonical signaling pathways. Ror2 was initially found to be highly expressed in osteosarcoma and renal cell carcinomas, and has recently been found in an increasingly long list of cancers currently including melanoma, colon cancer, melanoma, squamous cell carcinoma of the head and neck, and breast cancer. In the majority of these cancer types, Ror2 expression is associated with more aggressive disease states, consistent with a role mediating Wnt signaling regardless of the canonical or noncanonical signal. Because of the pattern of tissue distribution, the association with high-risk diseases, and the cell surface localization of this receptor, Ror2 has been identified as a potential high value target for therapeutic development. However, the recent discovery that Ror2 may function through non-kinase activities challenges this strategy and opens up opportunities to target this important molecule through alternative means.
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Affiliation(s)
- Zufan Debebe
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - W Kimryn Rathmell
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States; Department of Medicine, Division of Hematology and Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States; Department of Urology, Division of Hematology and Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States; Department of Genetics, Division of Hematology and Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
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14
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Dual-color dual-focus line-scanning FCS for quantitative analysis of receptor-ligand interactions in living specimens. Sci Rep 2015; 5:10149. [PMID: 25951521 PMCID: PMC4423563 DOI: 10.1038/srep10149] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 03/31/2015] [Indexed: 01/27/2023] Open
Abstract
Cellular communication in multi-cellular organisms is mediated to a large extent by a multitude of cell-surface receptors that bind specific ligands. An in-depth understanding of cell signaling networks requires quantitative information on ligand-receptor interactions within living systems. In principle, fluorescence correlation spectroscopy (FCS) based methods can provide such data, but live-cell applications have proven extremely challenging. Here, we have developed an integrated dual-color dual-focus line-scanning fluorescence correlation spectroscopy (2c2f lsFCS) technique that greatly facilitates live-cell and tissue experiments. Absolute ligand and receptor concentrations and their diffusion coefficients within the cell membrane can be quantified without the need to perform additional calibration experiments. We also determine the concentration of ligands diffusing in the medium outside the cell within the same experiment by using a raster image correlation spectroscopy (RICS) based analysis. We have applied this robust technique to study the interactions of two Wnt antagonists, Dickkopf1 and Dickkopf2 (Dkk1/2), to their cognate receptor, low-density-lipoprotein-receptor related protein 6 (LRP6), in the plasma membrane of living HEK293T cells. We obtained significantly lower affinities than previously reported using in vitro studies, underscoring the need to measure such data on living cells or tissues.
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15
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Schmitt M, Metzger M, Gradl D, Davidson G, Orian-Rousseau V. CD44 functions in Wnt signaling by regulating LRP6 localization and activation. Cell Death Differ 2015; 22:677-89. [PMID: 25301071 PMCID: PMC4356338 DOI: 10.1038/cdd.2014.156] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 07/31/2014] [Accepted: 08/18/2014] [Indexed: 11/09/2022] Open
Abstract
Wnt reception at the membrane is complex and not fully understood. CD44 is a major Wnt target gene in the intestine and is essential for Wnt-induced tumor progression in colorectal cancer. Here we show that CD44 acts as a positive regulator of the Wnt receptor complex. Downregulation of CD44 expression decreases, whereas CD44 overexpression increases Wnt activity in a concentration-dependent manner. Epistasis experiments place CD44 function at the level of the Wnt receptor LRP6. Mechanistically, CD44 physically associates with LRP6 upon Wnt treatment and modulates LRP6 membrane localization. Moreover, CD44 regulates Wnt signaling in the developing brain of Xenopus laevis embryos as shown by a decreased expression of Wnt targets tcf-4 and en-2 in CD44 morphants.
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Affiliation(s)
- M Schmitt
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus North, Postfach 3640, Karlsruhe 76021, Germany
| | - M Metzger
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus North, Postfach 3640, Karlsruhe 76021, Germany
| | - D Gradl
- Zoological Institute II, Karlsruhe Institute of Technology, Campus South, Postfach 6980, Karlsruhe 76128, Germany
| | - G Davidson
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus North, Postfach 3640, Karlsruhe 76021, Germany
| | - V Orian-Rousseau
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Campus North, Postfach 3640, Karlsruhe 76021, Germany
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16
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Asymmetry of VANGL2 in migrating lymphocytes as a tool to monitor activity of the mammalian WNT/planar cell polarity pathway. Cell Commun Signal 2015; 13:2. [PMID: 25627785 PMCID: PMC4314808 DOI: 10.1186/s12964-014-0079-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 12/17/2014] [Indexed: 11/29/2022] Open
Abstract
Background The WNT/planar-cell-polarity (PCP) pathway is a key regulator of cell polarity and directional cell movements. Core PCP proteins such as Van Gogh-like2 (VANGL2) are evolutionarily highly conserved; however, the mammalian PCP machinery is still poorly understood mainly due to lack of suitable models and quantitative methodology. WNT/PCP has been implicated in many human diseases with the most distinguished positive role in the metastatic process, which accounts for more than 90% of cancer related deaths, and presents therefore an attractive target for pharmacological interventions. However, cellular assays for the assessment of PCP signaling, which would allow a more detailed mechanistic analysis of PCP function and possibly also high throughput screening for chemical compounds targeting mammalian PCP signaling, are still missing. Results Here we describe a mammalian cell culture model, which correlates B lymphocyte migration of patient-derived MEC1 cells and asymmetric localization of fluorescently-tagged VANGL2. We show by live cell imaging that PCP proteins are polarized in MEC1 cells and that VANGL2 polarization is controlled by the same mechanism as in tissues i.e. it is dependent on casein kinase 1 activity. In addition, destruction of the actin cytoskeleton leads to migratory arrest and cell rounding while VANGL2-EGFP remains polarized suggesting that active PCP signaling visualized by polarized distribution of VANGL2 is a cause for and not a consequence of the asymmetric shape of a migrating cell. Conclusions The presented imaging-based methodology allows overcoming limitations of earlier approaches to study the mammalian WNT/PCP pathway, which required in vivo models and analysis of complex tissues. Our system investigating PCP-like signaling on a single-cell level thus opens new possibilities for screening of compounds, which control asymmetric distribution of proteins in the PCP pathway. Electronic supplementary material The online version of this article (doi:10.1186/s12964-014-0079-1) contains supplementary material, which is available to authorized users.
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17
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Endo M, Nishita M, Fujii M, Minami Y. Insight into the role of Wnt5a-induced signaling in normal and cancer cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 314:117-48. [PMID: 25619716 DOI: 10.1016/bs.ircmb.2014.10.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Wnt5a is involved in the activation of noncanonical Wnt signaling, including planar cell polarity (PCP) and Wnt-Ca(2+) pathways. The Ror-family of receptor tyrosine kinases is composed of Ror1 and Ror2 in mammals. Ror2 acts as a receptor or coreceptor for Wnt5a and regulates Wnt5a-induced activation of PCP pathway, and Wnt5a-Ror2 axis indeed plays critical roles in the developmental morphogenesis by regulating cell polarity and migration. Furthermore, Wnt5a-Ror2 axis is constitutively activated in cancer cells and confers highly motile and invasive properties on cancer cells through the expression of matrix metalloproteinase genes and enhanced formation of invadopodia. Meanwhile, Wnt5a also exhibits a tumor-suppressive function in certain cancers, including breast and colorectal carcinomas. Thus, it is of great importance to understand the respective molecular mechanisms governing Wnt5a-mediated tumor-progressive and tumor-suppressive functions, in order to develop novel and proper diagnostic and therapeutic strategies targeting Wnt5a signaling for human cancers.
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Affiliation(s)
- Mitsuharu Endo
- Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, Japan
| | - Michiru Nishita
- Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, Japan
| | - Masanori Fujii
- Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, Japan
| | - Yasuhiro Minami
- Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, Japan
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18
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Wallkamm V, Dörlich R, Rahm K, Klessing T, Nienhaus GU, Wedlich D, Gradl D. Live imaging of Xwnt5A-ROR2 complexes. PLoS One 2014; 9:e109428. [PMID: 25313906 PMCID: PMC4196911 DOI: 10.1371/journal.pone.0109428] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 08/30/2014] [Indexed: 12/26/2022] Open
Abstract
Secreted molecules of the Wnt family regulate key decisions in embryogenesis and adult tissue homeostasis by activating a complex network of Wnt signaling pathways. Although the different branches of Wnt signaling have been studied for more than 25 years, fluorophore tagged constructs for live cell imaging of Wnt molecules activating the Wnt/β-catenin pathway have become available only recently. We have generated a fluorophore tagged Wnt construct of the Xenopus Wnt5a protein (Xwnt5A) with the enhanced green fluorescent protein (EGFP), Xwnt5A-EGFP. This construct activates non-canonical Wnt pathways in an endocytosis dependent manner and is capable of compensating for the loss of endogenous Xwnt5A in Xenopus embryos. Strikingly, non-canonical Wnt pathway activation was restricted to short-range signaling while an inhibitory effect was observed in transwell cell cultures taken as long-range signaling model sytem. We used our Xwnt5A-EGFP construct to analyze in vivo binding of Wnt5A to its co-receptor ROR2 on the microscopic and on the molecular level. On the microscopic level, Xwnt5A-EGFP clusters in the membrane and recruits ROR2-mCherry to these clusters. Applying dual-colour dual-focus line-scanning fluorescence correlation spectroscopy on dorsal marginal zone explants, we identified membrane tethered Xwnt5A-EGFP molecules binding to ROR2-mCherry molecules. Our data favour a model, in which membrane-tethered Wnt-5A recruits ROR2 to form large ligand/receptor clusters and signals in an endocytosis-dependent manner.
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Affiliation(s)
- Veronika Wallkamm
- Zoological Institute, Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Rene Dörlich
- Institute of Applied Physics and Insitute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Karolin Rahm
- Zoological Institute, Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Tina Klessing
- Zoological Institute, Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics and Insitute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Doris Wedlich
- Zoological Institute, Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Dietmar Gradl
- Zoological Institute, Department of Cell and Developmental Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
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19
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A new mutation in the gene ROR2 causes brachydactyly type B1. Gene 2014; 547:106-10. [DOI: 10.1016/j.gene.2014.06.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/28/2014] [Accepted: 06/18/2014] [Indexed: 11/19/2022]
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20
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Wnt signaling through the Ror receptor in the nervous system. Mol Neurobiol 2013; 49:303-15. [PMID: 23990374 DOI: 10.1007/s12035-013-8520-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/18/2013] [Indexed: 01/04/2023]
Abstract
The receptor tyrosine kinase-like orphan receptor (Ror) proteins are conserved tyrosine kinase receptors that play roles in a variety of cellular processes that pattern tissues and organs during vertebrate and invertebrate development. Ror signaling is required for skeleton and neuronal development and modulates cell migration, cell polarity, and convergent extension. Ror has also been implicated in two human skeletal disorders, brachydactyly type B and Robinow syndrome. Rors are widely expressed during metazoan development including domains in the nervous system. Here, we review recent progress in understanding the roles of the Ror receptors in neuronal migration, axonal pruning, axon guidance, and synaptic plasticity. The processes by which Ror signaling execute these diverse roles are still largely unknown, but they likely converge on cytoskeletal remodeling. In multiple species, Rors have been shown to act as Wnt receptors signaling via novel non-canonical Wnt pathways mediated in some tissues by the adapter protein disheveled and the non-receptor tyrosine kinase Src. Rors can either activate or repress Wnt target expression depending on the cellular context and can also modulate signal transduction by sequestering Wnt ligands away from their signaling receptors. Future challenges include the identification of signaling components of the Ror pathways and bettering our understanding of the roles of these pleiotropic receptors in patterning the nervous system.
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21
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Abstract
In addition to activating β-catenin/TCF transcriptional complexes, Wnt proteins can elicit a variety of other responses. These are often lumped together under the denominator "alternative" or "non-canonical" Wnt signaling, but they likely comprise distinct signaling events. In this article, I discuss how the use of different ligand and receptor combinations is thought to give rise to these alternative Wnt-signaling responses. Although many of the biochemical details remain to be resolved, it is evident that alternative Wnt signaling plays important roles in regulating tissue morphogenesis during embryonic development.
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Affiliation(s)
- Renée van Amerongen
- Department of Developmental Biology, Stanford University, Stanford, California 94305, USA.
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22
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A switch from canonical to noncanonical Wnt signaling mediates drug resistance in colon cancer cells. PLoS One 2011; 6:e27308. [PMID: 22073312 PMCID: PMC3207861 DOI: 10.1371/journal.pone.0027308] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 10/13/2011] [Indexed: 02/07/2023] Open
Abstract
Butyrate, a fermentation product of fiber in the colon, acts as a histone deacetylase inhibitor (HDACi) and induces apoptosis in colon cancer (CC) cells in vitro. We have reported that the apoptotic effects of butyrate are dependent upon the hyperactivation of the Wnt/beta-catenin pathway. However, prolonged exposure of CC cells to increasing concentrations of butyrate results in the acquisition of resistance to the Wnt/beta-catenin- and apoptosis-inducing effects of this agent, as well as cross-resistance to structurally different HDACis. Here we report that one mechanism whereby HDACi resistance arises is through the increase of beta-catenin-independent (noncanonical) Wnt signaling. Compared to HDACi-sensitive HCT-116 CC cells, HDACi-resistant HCT-R cells exhibit higher levels of AKT/PKB cell survival signaling, which is in part induced by WNT5A and its receptor ROR2. The induction of AKT signaling by HDACis is also detected in other CC cell lines, albeit to a lesser extent than in the drug-resistant HCT-R cells. The observations suggested that the apoptotic effect of butyrate and other HDACis in CC cells can be augmented by inhibitors of pAKT. In agreement with the hypothesis, the combination of MK2206, a pAKT inhibitor, and a HDACi (butyrate or LBH589) induced higher apoptosis in CC cells compared to each agent alone. The exposure to both agents also re-sensitized the HCT-R cells to apoptosis. Finally, the concept of simultaneously inducing canonical Wnt activity and suppressing AKT signaling was translated into a combination of diet-derived agents. Diet-derived pAKT inhibitors (caffeic acid phethyl ester, sulforaphane, dilallyl trisulfide) suppressed the butyrate-induced levels of pAKT, and increased the apoptotic effects of butyrate in both drug-sensitive and drug-resistant CC cells. Our findings can be translated into (a) CC therapy employing combinations of synthetic HDACis and inhibitors of pAKT, as well as (b) CC prevention based upon diets that result in sufficient amounts of butyrate and pAKT inhibitors.
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23
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Stricker S, Mundlos S. FGF and ROR2 receptor tyrosine kinase signaling in human skeletal development. Curr Top Dev Biol 2011; 97:179-206. [PMID: 22074606 DOI: 10.1016/b978-0-12-385975-4.00013-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Skeletal malformations are among the most frequent developmental disturbances in humans. In the past years, progress has been made in unraveling the molecular mechanisms that govern skeletal development by the use of animal models as well as by the identification of numerous mutations that cause human skeletal syndromes. Receptor tyrosine kinases have critical roles in embryonic development. During formation of the skeletal system, the fibroblast growth factor receptor (FGFR) family plays major roles in the formation of cranial, axial, and appendicular bones. Another player of relevance to skeletal development is the unusual receptor tyrosine kinase ROR2, the function of which is as interesting as it is complex. In this chapter, we review the involvement of FGFR signaling in human skeletal disease and provide an update on the growing knowledge of ROR2.
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Affiliation(s)
- Sigmar Stricker
- Development and Disease Group, Max Planck-Institute for Molecular Genetics, Berlin, Germany
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