1
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Thompson EM, Patel V, Rajeeve V, Cutillas PR, Stoker AW. The cytotoxic action of BCI is not dependent on its stated DUSP1 or DUSP6 targets in neuroblastoma cells. FEBS Open Bio 2022; 12:1388-1405. [PMID: 35478300 PMCID: PMC9249316 DOI: 10.1002/2211-5463.13418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 04/04/2022] [Accepted: 04/26/2022] [Indexed: 12/04/2022] Open
Abstract
Neuroblastoma (NB) is a heterogeneous cancer of the sympathetic nervous system, which accounts for 7-10% of paediatric malignancies worldwide. Due to the lack of targetable molecular aberrations in NB, most treatment options remain relatively nonspecific. Here, we investigated the therapeutic potential of BCI, an inhibitor of DUSP1 and DUSP6, in cultured NB cells. BCI was cytotoxic in a range of NB cell lines and induced a short-lived activation of the AKT and stress-inducible MAP kinases, although ERK phosphorylation was unaffected. Furthermore, a phosphoproteomic screen identified significant upregulation of JNK signalling components and suppression in mTOR and R6K signalling. To assess the specificity of BCI, CRISPR-Cas9 was employed to introduce insertions and deletions in the DUSP1 and DUSP6 genes. Surprisingly, BCI remained fully cytotoxic in NB cells with complete loss of DUSP6 and partial depletion of DUSP1, suggesting that BCI exerts cytotoxicity in NB cells through a complex mechanism that is unrelated to these phosphatases. Overall, these data highlight the risk of using an inhibitor such as BCI as supposedly specific DUSP1/6, without understanding its full range of targets in cancer cells.
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Affiliation(s)
- Elliott M. Thompson
- Developmental Biology & Cancer Research and Teaching DepartmentUCL Great Ormond Street Institute of Child HealthLondonUK
| | - Vruti Patel
- Developmental Biology & Cancer Research and Teaching DepartmentUCL Great Ormond Street Institute of Child HealthLondonUK
- Present address:
Current Address: Discovery Research MRL UKMSDThe London Bioscience Innovation Centre (LBIC)LondonUK
| | - Vinothini Rajeeve
- Mass Spectrometry LaboratoryBarts Cancer InstituteQueen Mary University of LondonUK
| | - Pedro R Cutillas
- Mass Spectrometry LaboratoryBarts Cancer InstituteQueen Mary University of LondonUK
| | - Andrew W. Stoker
- Developmental Biology & Cancer Research and Teaching DepartmentUCL Great Ormond Street Institute of Child HealthLondonUK
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2
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Tagalakis AD, Jayarajan V, Maeshima R, Ho KH, Syed F, Wu L, Aldossary AM, Munye MM, Mistry T, Ogunbiyi OK, Sala A, Standing JF, Moghimi SM, Stoker AW, Hart SL. Integrin-Targeted, Short Interfering RNA Nanocomplexes for Neuroblastoma Tumor-Specific Delivery Achieve MYCN Silencing with Improved Survival. Adv Funct Mater 2021; 31:2104843. [PMID: 35712226 PMCID: PMC9178728 DOI: 10.1002/adfm.202104843] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Indexed: 06/15/2023]
Abstract
The authors aim to develop siRNA therapeutics for cancer that can be administered systemically to target tumors and retard their growth. The efficacy of systemic delivery of siRNA to tumors with nanoparticles based on lipids or polymers is often compromised by their rapid clearance from the circulation by the liver. Here, multifunctional cationic and anionic siRNA nanoparticle formulations are described, termed receptor-targeted nanocomplexes (RTNs), that comprise peptides for siRNA packaging into nanoparticles and receptor-mediated cell uptake, together with lipids that confer nanoparticles with stealth properties to enhance stability in the circulation, and fusogenic properties to enhance endosomal release within the cell. Intravenous administration of RTNs in mice leads to predominant accumulation in xenograft tumors, with very little detected in the liver, lung, or spleen. Although non-targeted RTNs also enter the tumor, cell uptake appears to be RGD peptide-dependent indicating integrin-mediated uptake. RTNs with siRNA against MYCN (a member of the Myc family of transcription factors) in mice with MYCN-amplified neuroblastoma tumors show significant retardation of xenograft tumor growth and enhanced survival. This study shows that RTN formulations can achieve specific tumor-targeting, with minimal clearance by the liver and so enable delivery of tumor-targeted siRNA therapeutics.
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Affiliation(s)
- Aristides D. Tagalakis
- Department of Genetics and Genomic MedicineUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
- Present address:
Department of BiologyEdge Hill UniversityOrmskirkL39 4QPUK
| | - Vignesh Jayarajan
- Department of Genetics and Genomic MedicineUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
| | - Ruhina Maeshima
- Department of Genetics and Genomic MedicineUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
| | - Kin H. Ho
- Department of InflammationInfection and ImmunityUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
| | - Farhatullah Syed
- Department of InflammationInfection and ImmunityUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
| | - Lin‐Ping Wu
- Centre for Pharmaceutical Nanotechnology and NanotoxicologyFaculty of Health and Medical SciencesUniversity of CopenhagenUniversitetsparken 2Copenhagen2100Denmark
- Present address:
Guangzhou institute of Biomedicine and HealthChinese Academy of SciencesGuangzhou510530People's Republic of China
| | - Ahmad M. Aldossary
- Department of Genetics and Genomic MedicineUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
- Present address:
National Center for BiotechnologyKing Abdulaziz City for Science and TechnologyRiyadh11442Saudi Arabia
| | - Mustafa M. Munye
- Department of Genetics and Genomic MedicineUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
- Present address:
Cell and Gene Therapy Catapult12th Floor Tower Wing, Guy's Hospital, Great Maze PondLondonSE1 9RTUK
| | - Talisa Mistry
- Department of HistopathologyGreat Ormond Street Hospital for ChildrenNHS Foundation TrustLondonWC1N 3JHUK
| | - Olumide Kayode Ogunbiyi
- Department of HistopathologyGreat Ormond Street Hospital for ChildrenNHS Foundation TrustLondonWC1N 3JHUK
| | - Arturo Sala
- Department of Life SciencesBrunel University LondonKingston LaneMiddlesexUB8 3PHUK
| | - Joseph F. Standing
- Department of InflammationInfection and ImmunityUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
| | - Seyed M. Moghimi
- Centre for Pharmaceutical Nanotechnology and NanotoxicologyFaculty of Health and Medical SciencesUniversity of CopenhagenUniversitetsparken 2Copenhagen2100Denmark
- Present address:
School of Pharmacy, and Translational and Clinical Research Institute, the Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUUK
- Present address:
Colorado Center for Nanomedicine and Nanosafety, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Andrew W. Stoker
- Department of Developmental Biology and CancerUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
| | - Stephen L. Hart
- Department of Genetics and Genomic MedicineUCL Great Ormond Street Institute of Child HealthUniversity College London30 Guilford StreetLondonWC1N 1EHUK
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Thompson EM, Stoker AW. A Review of DUSP26: Structure, Regulation and Relevance in Human Disease. Int J Mol Sci 2021; 22:ijms22020776. [PMID: 33466673 PMCID: PMC7828806 DOI: 10.3390/ijms22020776] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 01/10/2023] Open
Abstract
Dual specificity phosphatases (DUSPs) play a crucial role in the regulation of intracellular signalling pathways, which in turn influence a broad range of physiological processes. DUSP malfunction is increasingly observed in a broad range of human diseases due to deregulation of key pathways, most notably the MAP kinase (MAPK) cascades. Dual specificity phosphatase 26 (DUSP26) is an atypical DUSP with a range of physiological substrates including the MAPKs. The residues that govern DUSP26 substrate specificity are yet to be determined; however, recent evidence suggests that interactions with a binding partner may be required for DUSP26 catalytic activity. DUSP26 is heavily implicated in cancer where, akin to other DUSPs, it displays both tumour-suppressive and -promoting properties, depending on the context. Here we review DUSP26 by evaluating its transcriptional patterns, protein crystallographic structure and substrate binding, as well as its physiological role(s) and binding partners, its role in human disease and the development of DUSP26 inhibitors.
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4
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Bilip M, Shah S, Mathiyalakan M, Tagalakis AD, Hart SL, Maeshima R, Eaton S, Orford M, Irving E, Di Florio A, Simons C, Stoker AW. Liposomal delivery of hydrophobic RAMBAs provides good bioavailability and significant enhancement of retinoic acid signalling in neuroblastoma tumour cells. J Drug Target 2020; 28:643-654. [PMID: 31903789 PMCID: PMC7609071 DOI: 10.1080/1061186x.2019.1710157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/29/2019] [Accepted: 12/25/2019] [Indexed: 01/04/2023]
Abstract
Retinoid treatment is employed during residual disease treatment in neuroblastoma, where the aim is to induce neural differentiation or death in tumour cells. However, although therapeutically effective, retinoids have only modest benefits and suffer from poor pharmacokinetic properties. In vivo, retinoids induce CYP26 enzyme production in the liver, enhancing their own rapid metabolic clearance, while retinoid resistance in tumour cells themselves is considered to be due in part to increased CYP26 production. Retinoic acid metabolism blocking agents (RAMBAs), which inhibit CYP26 enzymes, can improve retinoic acid (RA) pharmacokinetics in pre-clinical neuroblastoma models. Here, we demonstrate that in cultured neuroblastoma tumour cells, RAMBAs enhance RA action as seen by morphological differentiation, AKT signalling and suppression of MYCN protein. Although active as retinoid enhancers, these RAMBAs are highly hydrophobic and their effective delivery in humans will be very challenging. Here, we demonstrate that such RAMBAs can be loaded efficiently into cationic liposomal particles, where the RAMBAs achieve good bioavailability and activity in cultured tumour cells. This demonstrates the efficacy of RAMBAs in enhancing retinoid signalling in neuroblastoma cells and shows for the first time that liposomal delivery of hydrophobic RAMBAs is a viable approach, providing novel opportunities for their delivery and application in humans.
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Affiliation(s)
- Maja Bilip
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Shreya Shah
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | | | | | - Stephen L. Hart
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Ruhina Maeshima
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Simon Eaton
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Michael Orford
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Elsa Irving
- Great Ormond Street Institute of Child Health, UCL, London, UK
| | | | - Claire Simons
- Great Ormond Street Institute of Child Health, UCL, London, UK
- School of Pharmacy and Pharmaceutical Sciences, College of Biomedical and Life Sciences, Cardiff University, Cardiff, UK
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5
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Maeshima R, Moulding D, Stoker AW, Hart SL. MYCN Silencing by RNAi Induces Neurogenesis and Suppresses Proliferation in Models of Neuroblastoma with Resistance to Retinoic Acid. Nucleic Acid Ther 2020; 30:237-248. [PMID: 32240058 DOI: 10.1089/nat.2019.0831] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Neuroblastoma (NB) is the most common solid tumor in childhood. Twenty percent of patients display MYCN amplification, which indicates a very poor prognosis. MYCN is a highly specific target for an NB tumor therapy as MYCN expression is absent or very low in most normal cells, while, as a transcription factor, it regulates many essential cell activities in tumor cells. We aim to develop a therapy for NB based on MYCN silencing by short interfering RNA (siRNA) molecules, which can silence target genes by RNA interference (RNAi), a naturally occurring method of gene silencing. It has been shown previously that MYCN silencing can induce apoptosis and differentiation in MYCN amplified NB. In this article, we have demonstrated that siRNA-mediated silencing of MYCN in MYCN-amplified NB cells induced neurogenesis in NB cells, whereas retinoic acid (RA) treatment did not. RA can differentiate NB cells and is used for treatment of residual disease after surgery or chemotherapy, but resistance can develop. In addition, MYCN siRNA treatment suppressed growth in a MYCN-amplified NB cell line more than that by RA. Our result suggests that gene therapy using RNAi targeting MYCN can be a novel therapy toward MYCN-amplified NB that have complete or partial resistance toward RA.
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Affiliation(s)
- Ruhina Maeshima
- Genetics and Genomic Medicine Department, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Dale Moulding
- UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Andrew W Stoker
- Developmental Biology & Cancer Department, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Stephen L Hart
- Genetics and Genomic Medicine Department, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
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6
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Seda M, Geerlings M, Lim P, Jeyabalan-Srikaran J, Cichon AC, Scambler PJ, Beales PL, Hernandez-Hernandez V, Stoker AW, Jenkins D. An FDA-Approved Drug Screen for Compounds Influencing Craniofacial Skeletal Development and Craniosynostosis. Mol Syndromol 2019; 10:98-114. [PMID: 30976283 PMCID: PMC6422125 DOI: 10.1159/000491567] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Neural crest stem/progenitor cells (NCSCs) populate a variety of tissues, and their dysregulation is implicated in several human diseases including craniosynostosis and neuroblastoma. We hypothesised that small molecules that inhibit NCSC induction or differentiation may represent potential therapeutically relevant drugs in these disorders. We screened 640 FDA-approved compounds currently in clinical use for other conditions to identify those which disrupt development of NCSC-derived skeletal elements that form the zebrafish jaw. In the primary screen, we used heterozygous transgenic sox10:gfp zebrafish to directly visualise NCSC-derived jaw cartilage. We noted partial toxicity of this transgene in relation to jaw patterning, suggesting that our primary screen was sensitised for NCSC defects, and we confirmed 10 novel, 4 previously reported, and 2 functional analogue drug hits in wild-type embryos. Of these drugs, 9/14 and 7/14, respectively, are known to target pathways implicated in osteoarthritis pathogenesis or to cause reduced bone mineral density/increased fracture risk as side effects in patients treated for other conditions, suggesting that our screen enriched for pathways targeting skeletal tissue homeostasis. We selected one drug that inhibited NCSC induction and one drug that inhibits bone mineralisation for further detailed analyses which reflect our initial hypotheses. These drugs were leflunomide and cyclosporin A, respectively, and their functional analogues, teriflunomide and FK506 (tacrolimus). We identified their critical developmental windows of activity, showing that the severity of defects observed related to the timing, duration, and dose of treatment. While leflunomide has previously been shown to inhibit NCSC induction, we demonstrate additional later roles in cartilage remodelling. Both drugs altered expression of extracellular matrix metalloproteinases. As proof-of-concept, we also tested drug treatment of disease-relevant mammalian cells. While leflunomide treatment inhibited the viability of several human NCSC-derived neuroblastoma cell lines coincident with altered expression of genes involved in ribosome biogenesis and transcription, FK506 enhanced murine calvarial osteoblast differentiation and prevented fusion of the coronal suture in calvarial explants taken from Crouzon syndrome mice.
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Affiliation(s)
- Marian Seda
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
| | - Maartje Geerlings
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
| | - Peggy Lim
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
| | | | - Ann-Christin Cichon
- Developmental Biology and Cancer Programmes, UCL Institute of Child Health, London, UK
| | - Peter J. Scambler
- Developmental Biology and Cancer Programmes, UCL Institute of Child Health, London, UK
| | - Philip L. Beales
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
| | | | - Andrew W. Stoker
- Developmental Biology and Cancer Programmes, UCL Institute of Child Health, London, UK
| | - Dagan Jenkins
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, UK
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7
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Maeshima R, Tagalakis AD, Stoker AW, Hart SL. 588. MYCN Silencing Using RNA Interference Causes Apoptosis and Differentiation in MYCN Amplified Neuroblastoma Cell Lines. Mol Ther 2016. [DOI: 10.1016/s1525-0016(16)33396-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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8
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Clark O, Park I, Di Florio A, Cichon AC, Rustin S, Jugov R, Maeshima R, Stoker AW. Oxovanadium-based inhibitors can drive redox-sensitive cytotoxicity in neuroblastoma cells and synergise strongly with buthionine sulfoximine. Cancer Lett 2014; 357:316-327. [PMID: 25444896 DOI: 10.1016/j.canlet.2014.11.039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 12/30/2022]
Abstract
In a wide range of neuroblastoma-derived lines oxovanadium compounds such as bis(maltolato)oxovanadium(IV) (BMOV) are cytotoxic. This is not explained by oxidative stress or inhibition of ion channels. Genotoxicity is unlikely given that a p53 response is absent and p53-mutant lines are also sensitive. Cytotoxicity is inhibited by N-acetyl cysteine and glutathione ester, indicating that BMOV action is sensitive to cytoplasmic redox and thiol status. Significantly, combining BMOV with glutathione synthesis inhibition greatly enhances BMOV-induced cell death. This combination treatment triggers high AKT pathway activation, highlighting the potential functional importance of PTP inhibition by BMOV. AKT activation itself, however, is not required for cytotoxicity. Oxovanadium compounds may thus represent novel leads as p53-independent therapeutics for neuroblastoma.
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Affiliation(s)
- Owen Clark
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Inhye Park
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Alessia Di Florio
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Ann-Christin Cichon
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Sarah Rustin
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Roman Jugov
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Ruhina Maeshima
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Andrew W Stoker
- Cancer Section, Developmental Biology & Cancer Programme, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
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9
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Coles CH, Mitakidis N, Zhang P, Elegheert J, Lu W, Stoker AW, Nakagawa T, Craig AM, Jones EY, Aricescu AR. Structural basis for extracellular cis and trans RPTPσ signal competition in synaptogenesis. Nat Commun 2014; 5:5209. [PMID: 25385546 PMCID: PMC4239663 DOI: 10.1038/ncomms6209] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/09/2014] [Indexed: 01/26/2023] Open
Abstract
Receptor protein tyrosine phosphatase sigma (RPTPσ) regulates neuronal extension and acts as a presynaptic nexus for multiple protein and proteoglycan interactions during synaptogenesis. Unknown mechanisms govern the shift in RPTPσ function, from outgrowth promotion to synaptic organization. Here, we report crystallographic, electron microscopic and small-angle X-ray scattering analyses, which reveal sufficient inter-domain flexibility in the RPTPσ extracellular region for interaction with both cis (same cell) and trans (opposite cell) ligands. Crystal structures of RPTPσ bound to its postsynaptic ligand TrkC detail an interaction surface partially overlapping the glycosaminoglycan-binding site. Accordingly, heparan sulphate and heparin oligomers compete with TrkC for RPTPσ binding in vitro and disrupt TrkC-dependent synaptic differentiation in neuronal co-culture assays. We propose that transient RPTPσ ectodomain emergence from the presynaptic proteoglycan layer allows capture by TrkC to form a trans-synaptic complex, the consequent reduction in RPTPσ flexibility potentiating interactions with additional ligands to orchestrate excitatory synapse formation.
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Affiliation(s)
- Charlotte H. Coles
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Nikolaos Mitakidis
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Peng Zhang
- Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5
| | - Jonathan Elegheert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Weixian Lu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Andrew W. Stoker
- Cancer Section, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, 702 Light Hall (0615), Nashville, Tennessee 37232-0615, USA
| | - Ann Marie Craig
- Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5
| | - E. Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A. Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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10
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Abstract
Receptor-like protein tyrosine phosphatases represent a large protein family related to cell adhesion molecules, with diverse roles throughout neural development in vertebrates and invertebrates. This review focuses on their roles in axon growth, guidance and repair, as well as more recent findings demonstrating their key roles in pre-synaptic and post-synaptic maturation and function. These enzymes have been linked to memory and neuropsychiatric defects in loss-of-function rodent models, highlighting their potential as future drug targets.
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Affiliation(s)
- Andrew W Stoker
- Institute of Child Health, University College London, United Kingdom.
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11
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Tchetchelnitski V, van den Eijnden M, Schmidt F, Stoker AW. Developmental co-expression and functional redundancy of tyrosine phosphatases with neurotrophin receptors in developing sensory neurons. Int J Dev Neurosci 2014; 34:48-59. [PMID: 24491805 DOI: 10.1016/j.ijdevneu.2014.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/22/2014] [Accepted: 01/22/2014] [Indexed: 12/11/2022] Open
Abstract
Receptor-type protein tyrosine phosphatases (RPTPs) have been implicated as direct or indirect regulators of neurotrophin receptors (TRKs). It remains less clear if and how such RPTPs might regulate TRK proteins in vivo during development. Here we present a comparative expression profile of RPTP genes and Trk genes during early stages of murine, dorsal root ganglion maturation. We find little if any specific, temporal mRNA co-regulation between individual RPTP and Ntrk genes between E12.5 and E14.5. Moreover, a double fluorescent in-situ hybridization and immunofluorescence study of seven Rptp genes with Ntrks revealed widespread co-expression of RPTPs in individual neurons, but no tight correlation with Trk expression profiles. No Rptp is expressed in 100% of Ntrk1-expressing neurons, whereas at least 6 RPTPs are expressed in 100% of Ntrk2- and Ntrk3-expressing neurons. An exception is Ptpro, which showed very selective expression. Short hairpin RNA suppression of Ptprf, Ptprs or Ptpro in primary, E13.5 DRG neurons did not alter TRK signalling. We therefore propose that TRK signalling may not be simply dependent on rate-limiting regulation by individual RPTP subtypes during sensory neuron development. Instead, TRK signalling has the potential to be buffered by concurrent inputs from several RPTPs in individual neurons.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/genetics
- Animals
- Cells, Cultured
- Embryo, Mammalian
- Ganglia, Spinal/cytology
- Ganglia, Spinal/embryology
- Gene Expression Regulation, Developmental/physiology
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- HEK293 Cells
- Humans
- Mice
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/metabolism
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/metabolism
- Regulatory-Associated Protein of mTOR
- Sensory Receptor Cells/metabolism
- Signal Transduction/genetics
- Transfection
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Affiliation(s)
- Viktoria Tchetchelnitski
- Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom
| | | | - Fanny Schmidt
- MERCK SERONO SA.-Geneva, 9 Chemin des Mines, CH-1202 Geneve, Switzerland
| | - Andrew W Stoker
- Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom.
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12
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Pulido R, Stoker AW, Hendriks WJAJ. PTPs emerge as PIPs: protein tyrosine phosphatases with lipid-phosphatase activities in human disease. Hum Mol Genet 2013; 22:R66-76. [PMID: 23900072 DOI: 10.1093/hmg/ddt347] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Protein tyrosine phosphatases (PTPs) constitute a family of key homeostatic regulators, with wide implications on physiology and disease. Recent findings have unveiled that the biological activity of PTPs goes beyond the dephosphorylation of phospho-proteins to shut down protein tyrosine kinase-driven signaling cascades. Substrates dephosphorylated by clinically relevant PTPs extend to phospholipids and phosphorylated carbohydrates as well. In addition, non-catalytic functions are also used by PTPs to regulate essential cellular functions. Consequently, PTPs have emerged as novel potential therapeutic targets for human diseases, including cancer predispositions, myopathies and neuropathies. In this review, we highlight recent advances on the multifaceted role of lipid-phosphatase PTPs in human pathology, with an emphasis on hereditary diseases. The involved PTP regulatory networks and PTP modulatory strategies with potential therapeutic application are discussed.
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Clark O, Daga S, Stoker AW. Tyrosine phosphatase inhibitors combined with retinoic acid can enhance differentiation of neuroblastoma cells and trigger ERK- and AKT-dependent, p53-independent senescence. Cancer Lett 2012; 328:44-54. [PMID: 23022267 DOI: 10.1016/j.canlet.2012.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 08/29/2012] [Accepted: 09/19/2012] [Indexed: 10/27/2022]
Abstract
Retinoic acid (RA)-induced differentiation therapy is partially successful in neuroblastoma treatment. We found that a novel combination of vanadium-based PTP inhibitors with RA induced extensive differentiation in neuroblastoma cells. In contrast to RA alone, this led to either permanent differentiation or senescence after 14days of combined treatment followed by chemical removal. Senescence was dependent in part on synergistic AKT and ERK activation. p21 was also strongly induced, but in contrast to oncogene-induced senescence, p53 was not activated. Vanadium-based inhibitors thus serve strongly to enhance RA's ability to drive differentiation and a novel form of senescence in neuroblastoma cells.
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Affiliation(s)
- Owen Clark
- Neural Development Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom
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14
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Chesini IM, Debyser G, Croes H, Ten Dam GB, Devreese B, Stoker AW, Hendriks WJAJ. PTPBR7 binding proteins in myelinating neurons of the mouse brain. Int J Biol Sci 2011; 7:978-91. [PMID: 21850207 PMCID: PMC3157272 DOI: 10.7150/ijbs.7.978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 07/21/2011] [Indexed: 12/29/2022] Open
Abstract
Mouse protein tyrosine phosphatase PTPBR7 is a receptor-like, transmembrane protein that is localized on the surface of neuronal cells. Its protein phosphatase activity is reduced upon multimerization, and PTPBR7-deficient mice display motor coordination defects. Extracellular molecules that may influence PTPBR7 activity, however, remain to be determined. We here show that the PTPBR7 extracellular domain binds to highly myelinated regions in mouse brain, in particular the white matter tracks in cerebellum. PTPBR7 deficiency does not alter this binding pattern, as witnessed by RAP in situ staining of Ptprr-/- mouse brain sections. Additional in situ and in vitro experiments also suggest that sugar moieties of heparan sulphate and chondroitin sulphate glycosaminoglycans are not critical for PTPBR7 binding. Candidate binding proteins were affinity-purified exploiting the PTPBR7 extracellular domain and identified by mass spectrometric means. Results support the suggested link between PTPRR isoforms and cerebellar calcium ion homeostasis, and suggest an additional role in the process of cell-cell adhesion.
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Affiliation(s)
- Irene M Chesini
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
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15
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16
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Hendriks WJAJ, Elson A, Harroch S, Stoker AW. Protein tyrosine phosphatases: functional inferences from mouse models and human diseases. FEBS J 2008; 275:816-30. [DOI: 10.1111/j.1742-4658.2008.06249.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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17
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Lee S, Faux C, Nixon J, Alete D, Chilton J, Hawadle M, Stoker AW. Dimerization of protein tyrosine phosphatase sigma governs both ligand binding and isoform specificity. Mol Cell Biol 2006; 27:1795-808. [PMID: 17178832 PMCID: PMC1820468 DOI: 10.1128/mcb.00535-06] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Signaling through receptor protein tyrosine phosphatases (RPTPs) can influence diverse processes, including axon development, lymphocyte activation, and cell motility. The molecular regulation of these enzymes, however, is still poorly understood. In particular, it is not known if, or how, the dimerization state of RPTPs is related to the binding of extracellular ligands. Protein tyrosine phosphatase sigma (PTPsigma) is an RPTP with major isoforms that differ in their complements of fibronectin type III domains and in their ligand-binding specificities. In this study, we show that PTPsigma forms homodimers in the cell, interacting at least in part through the transmembrane region. Using this knowledge, we provide the first evidence that PTPsigma ectodomains must be presented as dimers in order to bind heterophilic ligands. We also provide evidence of how alternative use of fibronectin type III domain complements in two major isoforms of PTPsigma can alter the ligand binding specificities of PTPsigma ectodomains. The data suggest that the alternative domains function largely to change the rotational conformations of the amino-terminal ligand binding sites of the ectodomain dimers, thus imparting novel ligand binding properties. These findings have important implications for our understanding of how heterophilic ligands interact with, and potentially regulate, RPTPs.
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Affiliation(s)
- Simon Lee
- Neural Development Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, United Kingdom
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18
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Alete DE, Weeks ME, Hovanession AG, Hawadle M, Stoker AW. Cell surface nucleolin on developing muscle is a potential ligand for the axonal receptor protein tyrosine phosphatase-sigma. FEBS J 2006; 273:4668-81. [PMID: 16995858 PMCID: PMC1866192 DOI: 10.1111/j.1742-4658.2006.05471.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Reversible tyrosine phosphorylation, catalyzed by receptor tyrosine kinases and receptor tyrosine phosphatases, plays an essential part in cell signaling during axonal development. Receptor protein tyrosine phosphatase-sigma has been implicated in the growth, guidance and repair of retinal axons. This phosphatase has also been implicated in motor axon growth and innervation. Insect orthologs of receptor protein tyrosine phosphatase-sigma are also implicated in the recognition of muscle target cells. A potential extracellular ligand for vertebrate receptor protein tyrosine phosphatase-sigma has been previously localized in developing skeletal muscle. The identity of this muscle ligand is currently unknown, but it appears to be unrelated to the heparan sulfate ligands of receptor protein tyrosine phosphatase-sigma. In this study, we have used affinity chromatography and tandem MS to identify nucleolin as a binding partner for receptor protein tyrosine phosphatase-sigma in skeletal muscle tissue. Nucleolin, both from tissue lysates and in purified form, binds to receptor protein tyrosine phosphatase-sigma ectodomains. Its expression pattern also overlaps with that of the receptor protein tyrosine phosphatase-sigma-binding partner previously localized in muscle, and nucleolin can also be found in retinal basement membranes. We demonstrate that a significant amount of muscle-associated nucleolin is present on the cell surface of developing myotubes, and that two nucleolin-binding components, lactoferrin and the HB-19 peptide, can block the interaction of receptor protein tyrosine phosphatase-sigma ectodomains with muscle and retinal basement membranes in tissue sections. These data suggest that muscle cell surface-associated nucleolin represents at least part of the muscle binding site for axonal receptor protein tyrosine phosphatase-sigma and that nucleolin may also be a necessary component of basement membrane binding sites of receptor protein tyrosine phosphatase-sigma.
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Affiliation(s)
- Daniel E. Alete
- Neural Development Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Mark E. Weeks
- Molecular Oncology, CRUK, Barts and The London School of Medicine and Dentistry, John Vane Centre, Charter House Square, London EC1M 6BQ, UK
| | - Ara G. Hovanession
- UPR 2228 CNRS, UFR Biomedicale-Universite Rene Descartes, 45 rue des Saints Peres, 75270 Paris Cedex 6, France
| | | | - Andrew W. Stoker
- Neural Development Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
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19
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Abstract
Receptor-type protein tyrosine phosphatases (RPTPs) are required for appropriate growth of axons during nervous system development in Drosophila. In the vertebrate, type IIa RPTPs [protein tyrosine phosphatase (PTP)-delta, PTP-sigma, and LAR (leukocyte common-antigen-related)] and the type III RPTP, PTP receptor type O (PTPRO), have been implicated in the regulation of axon growth, but their roles in developmental axon guidance are unclear. PTPRO, PTP-delta, and PTP-sigma are each expressed in chick motor neurons during the period of axonogenesis. To examine potential roles of RPTPs in axon growth and guidance in vivo, we used double-stranded RNA (dsRNA) interference combined with in ovo electroporation to knock down RPTP expression levels in the embryonic chick lumbar spinal cord. Although most branches of the developing limb nerves appeared grossly normal, a dorsal nerve identified as the anterior iliotibialis was clearly affected by dsRNA knock-down of RPTPs. In experimental embryos treated with dsRNA targeting PTP-delta, PTP-sigma, or PTPRO, this nerve showed abnormal fasciculation, was reduced in size, or was missing entirely; interference with PTPRO produced the most severe phenotypes. Control embryos electroporated with vehicle, or with dsRNA targeting choline acetyltransferase or axonin-1, did not exhibit this phenotype. Surprisingly, embryos electroporated with dsRNA targeting PTP-delta together with PTPRO, or all three RPTPs combined, had less severe phenotypes than embryos treated with PTPRO alone. This result suggests that competition between type IIa and type III RPTPs can regulate motor axon outgrowth, consistent with findings in Drosophila. Our results indicate that RPTPs, and especially PTPRO, are required for axon growth and guidance in the developing vertebrate limb.
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Affiliation(s)
- Laurie Stepanek
- Neuroscience Program, Miami Project to Cure Paralysis, University of Miami School of Medicine, Miami, Florida 33136, USA
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20
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Abstract
A cornerstone of many cell-signalling events rests on reversible phosphorylation of tyrosine residues on proteins. The reversibility relies on the coordinated actions of protein tyrosine kinases and protein tyrosine phosphatases (PTPs), both of which exist as large protein families. This review focuses on the rapidly evolving field of the PTPs. We now know that rather than simply scavenging phosphotyrosine, the PTPs specifically regulate a wide range of signalling pathways. To illustrate this and to highlight current areas of agreement and contention in the field, this review will present our understanding of PTP action in selected areas and will present current knowledge surrounding the regulatory mechanisms that control PTP enzymes themselves. It will be seen that PTPs control diverse processes such as focal adhesion dynamics, cell-cell adhesion and insulin signalling, and their own actions are in turn regulated by dimerisation, phosphorylation and reversible oxidation.
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Affiliation(s)
- Andrew W Stoker
- Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
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21
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Sajnani-Perez G, Chilton JK, Aricescu AR, Haj F, Stoker AW. Isoform-specific binding of the tyrosine phosphatase PTPsigma to a ligand in developing muscle. Mol Cell Neurosci 2003; 22:37-48. [PMID: 12595237 DOI: 10.1016/s1044-7431(02)00026-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PTPsigma is a receptor tyrosine phosphatase that is expressed widely in the developing nervous system and that controls the growth and retinotopic mapping of retinal axons. PTPsigma is also expressed in motor neurons where its function is unclear. Given that invertebrate relatives of PTPsigma can control motor axon guidance, target contact, and synaptogenesis, we have asked if extracellular ligands exist for cPTPsigma, the avian PTPsigma orthologue, in the neuromuscular system. Of the two major isoforms cPTPsigma1 and cPTPsigma2, only the shorter cPTPsigma1 isoform is expressed in developing spinal motor neurons and their axons. We show that ectodomains of cPTPsigma1, but not of cPTPsigma2, bind specifically to developing skeletal myotubes. The putative myotube ligand is not related to the previously described binding of cPTPsigma to heparan sulfates within the proteoglycans agrin and collagen XVIII, since heparinase treatment of myotubes does not alter cPTPsigma1 binding and since most mutations that abolish binding of cPTPsigma1 to heparin do not affect myotube binding. The expression of cPTPsigma1 in motor axons and its direct binding to target myotubes suggest an isoform-specific role for axonally expressed cPTPsigma1 during establishment or maintenance of neuromuscular contacts.
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MESH Headings
- Animals
- Axons/enzymology
- Axons/ultrastructure
- Binding Sites/genetics
- Collagen/genetics
- Collagen/metabolism
- Collagen Type XVIII
- Endostatins
- Fetus
- Gene Expression Regulation, Developmental/genetics
- Gene Expression Regulation, Enzymologic/genetics
- Growth Cones/enzymology
- Growth Cones/ultrastructure
- Heparan Sulfate Proteoglycans/metabolism
- Immunoglobulins/metabolism
- Ligands
- Mice
- Motor Neurons/cytology
- Motor Neurons/enzymology
- Muscle Fibers, Fast-Twitch/cytology
- Muscle Fibers, Fast-Twitch/enzymology
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/enzymology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/embryology
- Muscle, Skeletal/enzymology
- Neuromuscular Junction/cytology
- Neuromuscular Junction/embryology
- Neuromuscular Junction/enzymology
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Protein Binding/genetics
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Structure, Tertiary/physiology
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/metabolism
- RNA, Messenger/metabolism
- Receptor-Like Protein Tyrosine Phosphatases, Class 2
- Spinal Cord/cytology
- Spinal Cord/embryology
- Spinal Cord/enzymology
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Affiliation(s)
- Gustavo Sajnani-Perez
- Neural Development Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
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22
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Abstract
RPTPsigma is a cell adhesion molecule-like receptor protein tyrosine phosphatase involved in nervous system development. Its avian orthologue, known as cPTPsigma or CRYPalpha, promotes intraretinal axon growth and controls the morphology of growth cones. The molecular mechanisms underlying the functions of cPTPsigma are still to be determined, since neither its physiological ligand(s) nor its substrates have been described. Nevertheless, a major class of ligand(s) is present in the retinal basal lamina and glial endfeet, the potent native growth substrate for retinal axons. We demonstrate here that cPTPsigma is a heparin-binding protein and that its basal lamina ligands include the heparan sulfate proteoglycans (HSPGs) agrin and collagen XVIII. These molecules interact with high affinity with cPTPsigma in vitro, and this binding is totally dependent upon their heparan sulfate chains. Using molecular modelling and site-directed mutagenesis, a binding site for heparin and heparan sulfate was identified in the first immunoglobulin-like domain of cPTPsigma. HSPGs are therefore a novel class of heterotypic ligand for cPTPsigma, suggesting that cPTPsigma signaling in axons and growth cones is directly responsive to matrix-associated cues.
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Affiliation(s)
- A Radu Aricescu
- Neural Development Unit, Institute of Child Health, 30 Guilford Street, London WC1N 1EH, United Kingdom
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23
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Johnson KG, McKinnell IW, Stoker AW, Holt CE. Receptor protein tyrosine phosphatases regulate retinal ganglion cell axon outgrowth in the developing Xenopus visual system. J Neurobiol 2001; 49:99-117. [PMID: 11598918 DOI: 10.1002/neu.1068] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Receptor protein tyrosine phosphatases (RPTPs) are regulators of axon outgrowth and guidance in a variety of different vertebrate and invertebrate systems. Three RPTPs, CRYP-alpha, PTP-delta, and LAR, are expressed in overlapping but distinct patterns in the developing Xenopus retina, including expression in retinal ganglion cells (RGCs) as they send axons to the tectum (Johnson KG, Holt CE. 2000. Expression of CRYP-alpha, LAR, PTP-delta, and PTP-rho in the developing Xenopus visual system. Mech Dev 92:291-294). In order to examine the role of these RPTPs in visual system development, putative dominant negative RPTP mutants (CS-CRYP-alpha, CS-PTP-delta, and CS-LAR) were expressed either singly or in combination in retinal cells. No effect was found on either retinal cell fate determination or on gross RGC axon guidance to the tectum. However, expression of these CS-RPTP constructs differentially affected the rate of RGC axon outgrowth. In vivo, expression of all three CS-RPTPs or CS-PTP-delta alone inhibited RGC axon outgrowth, while CS-LAR and CS-CRYP-alpha had no significant effect. In vitro, expression of CS-CRYP-alpha enhanced neurite outgrowth, while CS-PTP-delta inhibited neurite outgrowth in a substrate-dependent manner. This study provides the first in vivo evidence that RPTPs regulate retinal axon outgrowth.
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MESH Headings
- Animals
- Avian Proteins
- Axons/physiology
- Blastomeres
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/physiology
- Chick Embryo
- Embryo, Nonmammalian/cytology
- Embryo, Nonmammalian/metabolism
- Eye Proteins/genetics
- Eye Proteins/physiology
- Female
- Gene Expression Regulation, Developmental
- Genes, Dominant
- Microinjections
- Models, Biological
- Multigene Family
- Mutagenesis, Site-Directed
- Nerve Tissue Proteins
- Neurites/physiology
- Optic Nerve/embryology
- Optic Nerve/enzymology
- Organ Culture Techniques
- Phosphorylation
- Protein Processing, Post-Translational
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/physiology
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/physiology
- Receptor-Like Protein Tyrosine Phosphatases
- Receptor-Like Protein Tyrosine Phosphatases, Class 2
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Recombinant Fusion Proteins/physiology
- Retina/transplantation
- Retinal Ganglion Cells/cytology
- Retinal Ganglion Cells/enzymology
- Superior Colliculi/embryology
- Superior Colliculi/enzymology
- Visual Pathways/cytology
- Visual Pathways/embryology
- Visual Pathways/enzymology
- Xenopus Proteins
- Xenopus laevis/embryology
- Xenopus laevis/metabolism
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Affiliation(s)
- K G Johnson
- Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom.
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24
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Stoker AW. Blood–brain barrier breached. Trends Genet 2001. [DOI: 10.1016/s0168-9525(01)02246-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Abstract
Receptor-like protein tyrosine phosphatases (RPTPs) continue to emerge as important signalling molecules in axons and their growth cones. Recent findings show that Drosophila RPTPs play key roles in guiding retinal axons and in preventing midline crossing of longitudinal axons. Vertebrate RPTPs are now implicated in controlling axon outgrowth, and preliminary evidence suggests that they too may influence axon guidance.
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Affiliation(s)
- A W Stoker
- Neural Development Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
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26
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Abstract
Receptor-like protein tyrosine phosphatases potentially play a crucial role in axon growth and targeting. We focus here on their role within the embryonic avian spinal cord, in particular the development and outgrowth of motorneurons. We have used in situ mRNA hybridization to examine the spatiotemporal expression of eight receptor-like protein tyrosine phosphatases and find that it is both dynamic and highly varied, including novel, isoform-specific expression patterns. CRYP alpha 1 is expressed in all of the ventral motorneuron pools, whereas CRYP2, RPTP gamma, and RPTP alpha are only expressed in specific subsets of these neurons. CRYP alpha 2, RPTP psi, and RPTP delta are neuronally expressed elsewhere in the cord, but not in ventral motorneurons, whereas RPTP mu is unique in being restricted to capillaries. The developmentally regulated expression of these genes strongly suggests that the encoded phosphatases play numerous roles during neurogenesis and axonogenesis in the vertebrate spinal cord.
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Affiliation(s)
- J K Chilton
- Neural Development Unit, Institute of Child Health, London, United Kingdom
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27
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Ledig MM, Haj F, Bixby JL, Stoker AW, Mueller BK. The receptor tyrosine phosphatase CRYPalpha promotes intraretinal axon growth. J Cell Biol 1999; 147:375-88. [PMID: 10525542 PMCID: PMC2174224 DOI: 10.1083/jcb.147.2.375] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/1999] [Accepted: 09/01/1999] [Indexed: 01/06/2023] Open
Abstract
Retinal ganglion cell axons grow towards the optic fissure in close contact with the basal membrane, an excellent growth substratum. One of the ligands of receptor tyrosine phosphatase CRYPalpha is located on the retinal and tectal basal membranes. To analyze the role of this RPTP and its ligand in intraretinal growth and guidance of ganglion cell axons, we disrupted ligand- receptor interactions on the retinal basal membrane in culture. Antibodies against CRYPalpha strongly reduced retinal axon growth on the basal membrane, and induced a dramatic change in morphology of retinal growth cones, reducing the size of growth cone lamellipodia. A similar effect was observed by blocking the ligand with a CRYPalpha ectodomain fusion protein. These effects did not occur, or were much reduced, when axons were grown either on laminin-1, on matrigel or on basal membranes with glial endfeet removed. This indicates that a ligand for CRYPalpha is located on glial endfeet. These results show for the first time in vertebrates that the interaction of a receptor tyrosine phosphatase with its ligand is crucial not only for promotion of retinal axon growth but also for maintenance of retinal growth cone lamellipodia on basal membranes.
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Affiliation(s)
- Matthias M. Ledig
- Max-Planck-Institut für Entwicklungsbiologie, Physikalische Biologie, D-72076 Tübingen, Germany
| | - Fawaz Haj
- Institute of Child Health, Neural Development Unit, University College London, London WC1N 1EH, United Kingdom
| | - John L. Bixby
- Department of Molecular and Cellular Pharmacology and Neuroscience Program, University of Miami School of Medicine, Miami, Florida 33101
| | - Andrew W. Stoker
- Institute of Child Health, Neural Development Unit, University College London, London WC1N 1EH, United Kingdom
| | - Bernhard K. Mueller
- Max-Planck-Institut für Entwicklungsbiologie, Physikalische Biologie, D-72076 Tübingen, Germany
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28
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Ledig MM, McKinnell IW, Mrsic-Flogel T, Wang J, Alvares C, Mason I, Bixby JL, Mueller BK, Stoker AW. Expression of receptor tyrosine phosphatases during development of the retinotectal projection of the chick. J Neurobiol 1999; 39:81-96. [PMID: 10213455 DOI: 10.1002/(sici)1097-4695(199904)39:1<81::aid-neu7>3.0.co;2-k] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Receptor tyrosine kinases and receptor protein tyrosine phosphatases (RPTPs) appear to coordinate many aspects of neural development, including axon growth and guidance. Here, we focus on the possible roles of RPTPs in the developing avian retinotectal system. Using both in situ hybridization analysis and immunohistochemistry, we show for the first time that five RPTP genes--CRYPalpha, CRYP-2, PTPmu, PTPgamma, and PTPalpha--have different but overlapping expression patterns throughout the retina and the tectum. PTPalpha is restricted to Muller glia cells and radial glia of the tectum, indicating a possible function in controlling neuronal migration. PTPgamma expression is restricted to amacrine neurons. CRYPalpha and CRYP-2 mRNAs in contrast are expressed throughout the retinal ganglion cell layer from where axons grow out to their tectal targets. PTPmu is expressed in a subset of these ganglion cells. CRYPalpha, CRYP-2, and PTPmu proteins are also localized in growth cones of retinal ganglion cell axons and are present in defined laminae of the tectum. Thus, the spatial and temporal expression of three distinct RPTP subtypes--CRYPalpha, CRYP-2, and PTPmu--are consistent with the possibility of their involvement in axon growth and guidance of the retinotectal projection.
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Affiliation(s)
- M M Ledig
- Max-Planck-Institut für Entwicklungsbiologie Abt. I, Tübingen, Germany
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29
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Abstract
Recent results have revealed for the first time that receptor-like protein tyrosine phosphatases help to control the navigation of motor axons in the Drosophila nervous system.
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Affiliation(s)
- A W Stoker
- Department of Human Anatomy, University of Oxford, UK
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30
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Stoker AW, Gehrig B, Newton MR, Bay BH. Comparative localisation of CRYP alpha, a CAM-like tyrosine phosphatase, and NgCAM in the developing chick visual system. Brain Res Dev Brain Res 1995; 90:129-40. [PMID: 8719336 DOI: 10.1016/0165-3806(96)83493-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The avian CRYP alpha gene is expressed in the embryonic nervous system and encodes a receptor-like protein tyrosine phosphatase with structural similarity to neural cell adhesion molecules. To gain further insight into the role of the CRYP alpha phosphatase in neural development, this study addresses the protein's cellular distribution in the well characterised embryonic visual system. High levels of CRYP alpha protein localise in retinal axons extending from the eye to the tectum throughout the major growth periods of these nerve processes. In addition, primitive inner plexiform layer processes in the retina, tectobulbar axons, and non-retinal fibres of the tectal stratum opticum, contain large amounts of CRYP alpha. Its presence in non-fasciculated processes suggests that CRYP alpha has a role other than in fasciculation in short range fibres. In contrast to CRYP alpha, NgCAM is confined largely to axon fascicles in the retina and tectum, consistent with its demonstrated role in fasciculation of cultured neurites. In cultured retinal neurons CRYP alpha proteins reside both in neurite processes and in growth cone membranes, implicating both of these as potential functional locations for the protein. Although CRYP alpha continues to be expressed in the later embryo, the strong, early expression suggests a significant developmental role in the initial growth or guidance of nerve processes. This applies both over the longer range in the retinotectal and tectobulbar projections and over the shorter range within plexiform layers.
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Affiliation(s)
- A W Stoker
- Department of Human Anatomy, University of Oxford, UK.
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31
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Stoker AW, Gehrig B, Haj F, Bay BH. Axonal localisation of the CAM-like tyrosine phosphatase CRYP alpha: a signalling molecule of embryonic growth cones. Development 1995; 121:1833-44. [PMID: 7600997 DOI: 10.1242/dev.121.6.1833] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Migrating embryonic growth cones require multiple, membrane-associated signalling molecules to monitor and respond to guidance cues. Here we present the first evidence that vertebrate cell adhesion molecule-like protein tyrosine phosphatases are likely to be components of this signalling system. CRYP alpha, the gene for an avian cell adhesion molecule-like phosphatase, is strongly expressed in the embryonic nervous system. In this study we have immunolocalised the protein in the early chick embryo and demonstrated its predominant localisation in axons of the central and peripheral nervous systems. This location suggests that the major, early role of the enzyme is in axonal development. In a study of sensory neurites in culture, we furthermore show that this phosphatase localises in migrating growth cones, within both the lamellipodia and filopodia. The dependence of growth cone migration on both cell adhesion and signalling through phosphotyrosine turnover, places the cell adhesion molecule-like CRYP alpha phosphatase in a position to be a regulator of these processes.
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Affiliation(s)
- A W Stoker
- Department of Human Anatomy, University of Oxford, UK
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Abstract
The controlled development of embryo cells depends on their ability to monitor and respond to dynamic microenvironmental signals. This is frequently effected through membrane-associated receptor proteins which signal directly or indirectly through protein tyrosine phosphorylation. A search for such proteins in the developing nervous system of the chick has identified a new receptor-like protein tyrosine phosphatase (R-PTP) gene which may be responsible in part for this signalling. This gene, named CRYP alpha, is related to the LAR subfamily of R-PTPs and has extracellular homology to the neural cell adhesion molecules (CAMs). The gene is widely expressed in both the central and peripheral nervous systems, with particularly strong expression in motor neurons and in brain subregions such as the optic tectum and hypothalamus. Expression is seen both in early proliferating neuroepithelia and in subsets of post-mitotic nerve cells. Moreover, tissue-specific and developmentally-regulated exon use has been found in the brain, suggesting that isoforms of the R-PTP protein have stage-specific neural roles. This alternative RNA splicing event affects the encoded structure of the CAM-like domain, which may in turn influence its ligand binding properties. The novel, regulated expression of this R-PTP gene suggests that it plays a role in early neural development, and that the signalling properties of the encoded phosphatase can be modified according to the differentiated state of the cells.
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Affiliation(s)
- A W Stoker
- Department of Human Anatomy, University of Oxford, England, UK
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Abstract
Previous studies have indicated that the regression versus progression of v-src-DNA-induced sarcomas is dependent on chicken line. As a first step in analyzing the role of tumor immunity as a determinant of this line dependence, experiments were undertaken to ascertain whether an antisarcoma immune response is generated in the course of sarcoma growth in TK chickens, a regressor line. To assay for this response, test TK chickens in which v-src-induced wing web sarcomas had regressed, as well as control TK chickens that had not been exposed to v-src, were challenged in protocols known to yield v-src-dependent sarcoma formation and monitored for challenge sarcoma growth. Compared with the control chickens, the test chickens showed a significant resistance to the sarcomagenic challenge. These results raise the possibility that the antisarcoma response that is inducible in regressor lines, as demonstrated here in terms of a protective effect against a subsequent sarcomagenic challenge, may also underlie the regression of v-src-induced primary sarcomas.
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MESH Headings
- Animals
- Avian Sarcoma Viruses/genetics
- Avian Sarcoma Viruses/physiology
- Chickens
- DNA, Neoplasm/isolation & purification
- DNA, Viral/genetics
- DNA, Viral/isolation & purification
- Defective Viruses/genetics
- Defective Viruses/physiology
- Genes, src
- Neoplasm Regression, Spontaneous/genetics
- Neoplasm Regression, Spontaneous/immunology
- Neoplasm Regression, Spontaneous/pathology
- Plasmids
- Restriction Mapping
- Sarcoma, Experimental/immunology
- Sarcoma, Experimental/microbiology
- Sarcoma, Experimental/pathology
- Species Specificity
- Virus Replication/genetics
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Affiliation(s)
- T W Wisner
- Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104
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Reddy ST, Stoker AW, Bissell MJ. Expression of Rous sarcoma virus-derived retroviral vectors in the avian blastoderm: potential as stable genetic markers. Proc Natl Acad Sci U S A 1991; 88:10505-9. [PMID: 1660139 PMCID: PMC52957 DOI: 10.1073/pnas.88.23.10505] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Retroviruses are valuable tools in studies of embryonic development, both as gene expression vectors and as cell lineage markers. In this study early chicken blastoderm cells are shown to be permissive for infection by Rous sarcoma virus and derivative replication-defective vectors, and, in contrast to previously published data, these cells will readily express viral genes. In cultured blastoderm cells, Rous sarcoma virus stably integrates and is transcribed efficiently, producing infectious virus particles. Using replication-defective vectors encoding the bacterial lacZ gene, we further show that blastoderms can be infected in culture and in ovo. In ovo, lacZ expression is seen within 24 hr of virus inoculation, and by 96 hr stably expressing clones of cells are observed in diverse tissues throughout the embryo, including epidermis, somites, and heart, as well as in extraembryonic membranes. Given the rapid onset of vector expression and the broad range of permissive cell types, it should be feasible to use Rous sarcoma virus-derived retroviruses as early lineage markers and expression vectors beginning at the blastoderm stage of avian embryogenesis.
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Affiliation(s)
- S T Reddy
- Division of Cell and Molecular Biology, Lawrence Berkeley Laboratory, CA 94720
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Affiliation(s)
- A W Stoker
- Division of Cell and Molecular Biology, Lawrence Berkeley Laboratory, Berkeley, California
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36
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Affiliation(s)
- A W Stoker
- Laboratory of Cell Biology, Lawrence Berkeley Laboratory, Berkeley, CA 94720
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37
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Stoker AW, Hatier C, Bissell MJ. The embryonic environment strongly attenuates v-src oncogenesis in mesenchymal and epithelial tissues, but not in endothelia. J Biophys Biochem Cytol 1990; 111:217-28. [PMID: 2164029 PMCID: PMC2116154 DOI: 10.1083/jcb.111.1.217] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We demonstrate that the behavior of cells expressing v-src, a tyrosine kinase oncogene, differs profoundly between the embryonic and culture environments. V-src was introduced into avian embryo cells both in culture and in stage-24 embryo limbs, using replication-defective retroviral vectors. These vectors were used as single-hit, cellular markers to determine the environmental influences imposed by normal cells and tissues on clonal cell growth. The marker gene lacZ was coexpressed with v-src in order to locate the descendent cells. In culture, v-src induced rapid morphological transformation and anchorage-independent growth of embryo fibroblasts; the vectors were also tumorigenic in hatchling chickens. In contrast, most of the cell clones expressing v-src in the embryo grew normally without neoplasia. Expression of v-src vectors could be found in a wide range of cell types, demonstrating not only that neoplastic transformation is attenuated in ovo, but also that differentiation commitment in many lineages can be maintained concurrently with oncogene expression. Significantly, the embryonic control of cell growth could be perturbed by v-src under certain conditions. Rare, marked clones showed hyperplasia or dysplasia, and the primitive endothelium could succumb to rapid neoplasia; thus, these embryonic tissues are not inherently deficient in transformation factors. We propose that the environmental conditions imposed on cells in ovo are critical for the attenuation of neoplasia, while cultured cells lose this requisite environment.
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Affiliation(s)
- A W Stoker
- Division of Cell and Molecular Biology, Lawrence Berkeley Laboratory, University of California, Berkeley 94720
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Stoker AW, Sieweke MH. v-src induces clonal sarcomas and rapid metastasis following transduction with a replication-defective retrovirus. Proc Natl Acad Sci U S A 1989; 86:10123-7. [PMID: 2557619 PMCID: PMC298657 DOI: 10.1073/pnas.86.24.10123] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
v-src is an effective carcinogen when expressed from Rous sarcoma virus (RSV) in vivo. Whereas RSV tumors require sustained oncogene expression, their growth is largely a balance between viral recruitment of tissues and host immune destruction of infected cells. We have therefore examined the tumorigenic potential of v-src in the absence of viral recruitment and viral antigen expression. v-src was introduced with high efficiency into chicken wing web tissues using replication-defective (rd) retroviral vectors. Clonal sarcomas were induced rapidly, and, furthermore, v-src potentiated metastatic progression in approximately 0.1%-1% of tumor clones with unexpectedly short latency. rd vectors proved effective not only in transducing v-src into tissues but also as insertional markers of tumor clonality. The rd vector present in most primary and metastatic tumors was a highly truncated form of RSV derived by viral transmission of spliced v-src mRNA; this vector should thus avoid viral recruitment and host anti-viral immune reaction through its complete lack of viral structural genes. Under such conditions v-src maintains strong carcinogenicity in vivo when restricted to clonal tumor growth and can confer rapid metastatic potential on a discrete subset of tumor clones.
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Affiliation(s)
- A W Stoker
- Division of Cell and Molecular Biology, Lawrence Berkeley Laboratory, University of California 94720
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Sieweke MH, Stoker AW, Bissell MJ. Evaluation of the cocarcinogenic effect of wounding in Rous sarcoma virus tumorigenesis. Cancer Res 1989; 49:6419-24. [PMID: 2553256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chickens given injections of Rous sarcoma virus form sarcomas at the site of inoculation (primary tumor) and at the site of experimentally introduced wounds (wound tumor). This latter finding provides a model system to study systematically the mechanisms underlying the cocarcinogenic effects of wounding. Our experiments show the following. (a) Chickens inoculated with a Rous sarcoma virus-derived, replication-defective virus construct fail to elaborate wound tumors in spite of aggressively growing primary tumors. We thus rule out metastasis as a mechanism and conclude that infectious virus is required for wound tumor formation; (b) using bromodeoxyuridine incorporation and immunofluorescence on frozen sections we demonstrate proliferation in the unwounded wing in cell types which are normally targets for Rous sarcoma virus infection and transformation and conclude that proliferation per se is not sufficient to induce wound tumors; (c) using immunohistochemistry for the viral protein p19gag we show that wounding induces virus expression in fibroblasts of newly forming granulation tissue 2 days after injury. We also demonstrate expression of viral mRNA in wound tumors by in situ hybridization with a v-src probe. We discuss the possibility of activation of integrated, silent virus or the preferential infection of a special target cell population as a result of wounding as well as the potential role of wound factors in transformation.
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Affiliation(s)
- M H Sieweke
- Division of Cell and Molecular Biology, Lawrence Berkeley Laboratory, University of California, Berkeley 94720
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40
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Abstract
We have constructed an avian leukosis virus derivative with a 5' deletion extending from within the tRNA primer binding site to a SacI site in the leader region. Our aim was to remove cis-acting replicative and/or encapsidation sequences and to use this derivative, RAV-1 psi-, to develop vector-packaging cell lines. We show that RAV-1 psi- can be stably expressed in the quail cell line QT6 and chicken embryo fibroblasts and that it is completely replication deficient in both cell types. Moreover, we have demonstrated that QT6-derived lines expressing RAV-1 psi- can efficiently package four structurally different replication-defective v-src expression vectors into infectious virus, with very low or undetectable helper virus release. These RAV-1 psi--expressing cell lines comprise the first prototype avian sarcoma and leukosis virus-based vector-packaging system. The construction of our vectors has also shown us that a sequence present within gag, thought to facilitate virus packaging, is not necessary for efficient vector expression and high virus production. We show that quantitation and characterization of replication-defective viruses can be achieved with a sensitive immunocytochemical procedure, presenting an alternative to internal selectable vector markers.
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Affiliation(s)
- A W Stoker
- Laboratory of Cell Biology, University of California, Berkeley 94720
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41
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Abstract
A simple and accurate immunocytochemical focus assay is described, whereby both transforming and non-transforming avian retroviruses can be enumerated. After virus infection of chick embryo fibroblasts, an agar overlay is applied; foci of infected cells (expression foci) are detected immunocytochemically after 5 to 7 days. The primary antibodies are monoclonal sera directed against either viral p19gag or pp60v-src. Detection of expression foci after transfection of cells with cloned viral DNA is also demonstrated.
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Affiliation(s)
- A W Stoker
- Division of Biology and Medicine, Lawrence Berkeley Laboratory, University of California, Berkeley 94720
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Stoker AW, Kellie S, Wyke JA. Intracellular localization and processing of pp60v-src proteins expressed by two distinct temperature-sensitive mutants of Rous sarcoma virus. J Virol 1986; 58:876-83. [PMID: 3009893 PMCID: PMC252995 DOI: 10.1128/jvi.58.3.876-883.1986] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The transforming protein of Rous sarcoma virus, pp60v-src, is known to be a tyrosine protein kinase, but the mechanism of cell transformation remains unclear. In further investigating pp60v-src structure and function, we have analyzed two temperature-sensitive (ts) Rous sarcoma virus src gene mutants, tsLA29 and tsLA32. The mutations in tsLA29 and tsLA32 map in the carboxy-terminal region and the amino-terminal half of pp60v-src, respectively, and encode mutant proteins with either temperature-labile (tsLA29) or -stable (tsLA32) kinase activities. Here we examined the intracellular processing and localization of these pp60v-src mutants and extended our characterization of transformation parameters expressed by cells infected by the Rous sarcoma virus variants. No obvious defects in functional integrity of the tsLA32 pp60v-src could yet be demonstrated, whereas the tsLA29 pp60v-src was perturbed not only in kinase activity, but also in aspects of protein processing and localization. Analysis of transformation parameters expressed by infected cells demonstrated the complete temperature lability of both mutants.
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Wyke JA, Stoker AW, Searle S, Spooncer E, Simmons P, Dexter TM. Perturbed hemopoiesis and the generation of multipotential stem cell clones in src-infected bone marrow cultures is an indirect or transient effect of the oncogene. Mol Cell Biol 1986; 6:959-63. [PMID: 3095630 PMCID: PMC367598 DOI: 10.1128/mcb.6.3.959-963.1986] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Multipotential stem cell lines, derived specifically from long-term bone marrow cultures infected with a recombinant retrovirus carrying v-src, lack v-src. Stable consequences thus result from transient actions or indirect effects of v-src on other cells, with the latter possibility being favored by its mosaic expression in marrow cultures.
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Stoker AW, Enrietto PJ, Wyke JA. Functional domains of the pp60v-src protein as revealed by analysis of temperature-sensitive Rous sarcoma virus mutants. Mol Cell Biol 1984; 4:1508-14. [PMID: 6092915 PMCID: PMC368941 DOI: 10.1128/mcb.4.8.1508-1514.1984] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Four temperature-sensitive (ts) Rous sarcoma virus src gene mutants with lesions in different parts of the gene represent three classes of alteration in pp60src. These classes are composed of mutants with (i) heat-labile protein kinase activities both in vitro and in vivo (tsLA27 and tsLA29), (ii) heat-labile kinases in vivo but not in vitro (tsLA33), and (iii) neither in vivo nor in vitro heat-labile kinases (tsLA32). The latter class indicates the existence of structural or functional pp60src domains that are required for transformation but do not grossly affect tyrosine kinase activity.
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