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Hendriks WJAJ, van Cruchten RTP, Pulido R. Hereditable variants of classical protein tyrosine phosphatase genes: Will they prove innocent or guilty? Front Cell Dev Biol 2023; 10:1051311. [PMID: 36755664 PMCID: PMC9900141 DOI: 10.3389/fcell.2022.1051311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 12/28/2022] [Indexed: 01/24/2023] Open
Abstract
Protein tyrosine phosphatases, together with protein tyrosine kinases, control many molecular signaling steps that control life at cellular and organismal levels. Impairing alterations in the genes encoding the involved proteins is expected to profoundly affect the quality of life-if compatible with life at all. Here, we review the current knowledge on the effects of germline variants that have been reported for genes encoding a subset of the protein tyrosine phosphatase superfamily; that of the thirty seven classical members. The conclusion must be that the newest genome research tools produced an avalanche of data that suggest 'guilt by association' for individual genes to specific disorders. Future research should face the challenge to investigate these accusations thoroughly and convincingly, to reach a mature genotype-phenotype map for this intriguing protein family.
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Affiliation(s)
- Wiljan J. A. J. Hendriks
- Department of Cell Biology, Radboud University Medical Centre, Nijmegen, The Netherlands,*Correspondence: Wiljan J. A. J. Hendriks,
| | | | - Rafael Pulido
- Biomarkers in Cancer Unit, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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2
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Kirstein M, Cambrils A, Segarra A, Melero A, Varea E. Cholinergic Senescence in the Ts65Dn Mouse Model for Down Syndrome. Neurochem Res 2022; 47:3076-3092. [PMID: 35767135 PMCID: PMC9470680 DOI: 10.1007/s11064-022-03659-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 06/08/2022] [Accepted: 06/14/2022] [Indexed: 11/29/2022]
Abstract
Down syndrome (DS) induces a variable phenotype including intellectual disabilities and early development of Alzheimer’s disease (AD). Moreover, individuals with DS display accelerated aging that affects diverse organs, among them the brain. The Ts65Dn mouse is the most widely used model to study DS. Progressive loss of cholinergic neurons is one of the hallmarks of AD present in DS and in the Ts65Dn model. In this study, we quantify the number of cholinergic neurons in control and Ts65Dn mice, observing a general reduction in their number with age but in particular, a greater loss in old Ts65Dn mice. Increased expression of the m1 muscarinic receptor in the hippocampus counteracts this loss. Cholinergic neurons in the Ts65Dn mice display overexpression of the early expression gene c-fos and an increase in the expression of β-galactosidase, a marker of senescence. A possible mechanism for senescence induction could be phosphorylation of the transcription factor FOXO1 and its retention in the cytoplasm, which we are able to confirm in the Ts65Dn model. In our study, using Ts65Dn mice, we observe increased cholinergic activity, which induces a process of early senescence that culminates in the loss of these neurons.
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Affiliation(s)
- Martina Kirstein
- Cell Biology Department, Universitat de València, Dr. Moliner, 50, Burjassot, 46100, València, Spain
| | - Alba Cambrils
- Cell Biology Department, Universitat de València, Dr. Moliner, 50, Burjassot, 46100, València, Spain
| | - Ana Segarra
- Cell Biology Department, Universitat de València, Dr. Moliner, 50, Burjassot, 46100, València, Spain
| | - Ana Melero
- Cell Biology Department, Universitat de València, Dr. Moliner, 50, Burjassot, 46100, València, Spain
| | - Emilio Varea
- Cell Biology Department, Universitat de València, Dr. Moliner, 50, Burjassot, 46100, València, Spain.
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Cornejo F, Cortés BI, Findlay GM, Cancino GI. LAR Receptor Tyrosine Phosphatase Family in Healthy and Diseased Brain. Front Cell Dev Biol 2021; 9:659951. [PMID: 34966732 PMCID: PMC8711739 DOI: 10.3389/fcell.2021.659951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 11/17/2021] [Indexed: 11/23/2022] Open
Abstract
Protein phosphatases are major regulators of signal transduction and they are involved in key cellular mechanisms such as proliferation, differentiation, and cell survival. Here we focus on one class of protein phosphatases, the type IIA Receptor-type Protein Tyrosine Phosphatases (RPTPs), or LAR-RPTP subfamily. In the last decade, LAR-RPTPs have been demonstrated to have great importance in neurobiology, from neurodevelopment to brain disorders. In vertebrates, the LAR-RPTP subfamily is composed of three members: PTPRF (LAR), PTPRD (PTPδ) and PTPRS (PTPσ), and all participate in several brain functions. In this review we describe the structure and proteolytic processing of the LAR-RPTP subfamily, their alternative splicing and enzymatic regulation. Also, we review the role of the LAR-RPTP subfamily in neural function such as dendrite and axon growth and guidance, synapse formation and differentiation, their participation in synaptic activity, and in brain development, discussing controversial findings and commenting on the most recent studies in the field. Finally, we discuss the clinical outcomes of LAR-RPTP mutations, which are associated with several brain disorders.
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Affiliation(s)
- Francisca Cornejo
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Bastián I Cortés
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Greg M Findlay
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Gonzalo I Cancino
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.,Escuela de Biotecnología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
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Choi Y, Nam J, Whitcomb DJ, Song YS, Kim D, Jeon S, Um JW, Lee SG, Woo J, Kwon SK, Li Y, Mah W, Kim HM, Ko J, Cho K, Kim E. SALM5 trans-synaptically interacts with LAR-RPTPs in a splicing-dependent manner to regulate synapse development. Sci Rep 2016; 6:26676. [PMID: 27225731 PMCID: PMC4881023 DOI: 10.1038/srep26676] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 05/04/2016] [Indexed: 11/08/2022] Open
Abstract
Synaptogenic adhesion molecules play critical roles in synapse formation. SALM5/Lrfn5, a SALM/Lrfn family adhesion molecule implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons, but its presynaptic ligand remains unknown. We found that SALM5 interacts with the Ig domains of LAR family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPδ, and PTPσ). These interactions are strongly inhibited by the splice insert B in the Ig domain region of LAR-RPTPs, and mediate SALM5-dependent presynaptic differentiation in contacting axons. In addition, SALM5 regulates AMPA receptor-mediated synaptic transmission through mechanisms involving the interaction of postsynaptic SALM5 with presynaptic LAR-RPTPs. These results suggest that postsynaptic SALM5 promotes synapse development by trans-synaptically interacting with presynaptic LAR-RPTPs and is important for the regulation of excitatory synaptic strength.
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Affiliation(s)
- Yeonsoo Choi
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Jungyong Nam
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Daniel J. Whitcomb
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, United Kingdom
| | - Yoo Sung Song
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Gyeonggi-do, 463–707, Korea
| | - Doyoun Kim
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
| | - Sangmin Jeon
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Ji Won Um
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
- Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Seong-Gyu Lee
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Jooyeon Woo
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Seok-Kyu Kwon
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Yan Li
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
| | - Won Mah
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Ho Min Kim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 305-701, Korea
| | - Jaewon Ko
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Kwangwook Cho
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, United Kingdom
- Centre for Synaptic Plasticity, University of Bristol, Bristol BS1 3NY, United Kingdom
| | - Eunjoon Kim
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 305-701, Korea
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science (IBS), Daejeon 305-701, Korea
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Sarhan AR, Patel TR, Cowell AR, Tomlinson MG, Hellberg C, Heath JK, Cunningham DL, Hotchin NA. LAR protein tyrosine phosphatase regulates focal adhesions via CDK1. J Cell Sci 2016; 129:2962-71. [DOI: 10.1242/jcs.191379] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/21/2016] [Indexed: 12/12/2022] Open
Abstract
Focal adhesions are complex multi-molecular structures that link the actin cytoskeleton to the extracellular matrix via integrin adhesion receptors and play a key role in regulation of many cellular functions. LAR is a receptor protein tyrosine phosphatase that regulates PDGF signalling and localises to focal adhesions. We have observed that loss of LAR phosphatase activity in mouse embryonic fibroblasts results in reduced numbers of focal adhesions and decreased adhesion to fibronectin. To understand how LAR regulates cell adhesion we used phosphoproteomic data, comparing global phosphorylation events in wild type and LAR phosphatase-deficient cells, to analyse differential kinase activity. Kinase prediction analysis of LAR-regulated phosphosites identified a node of cytoskeleton- and adhesion-related proteins centred on cyclin-dependent kinase-1 (CDK1). We found that loss of LAR activity resulted in reduced activity of CDK1, and that CDK1 activity was required for LAR-mediated focal adhesion complex formation. We also established that LAR regulates CDK1 activity via c-Abl and PKB/Akt. In summary, we have identified a novel role for a receptor protein tyrosine phosphatase in regulating CDK1 activity and hence cell adhesion to the extracellular matrix.
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Affiliation(s)
- Adil R. Sarhan
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Trushar R. Patel
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Alana R. Cowell
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Michael G. Tomlinson
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Carina Hellberg
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - John K. Heath
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Debbie L. Cunningham
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Neil A. Hotchin
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
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Hendriks WJAJ, Pulido R. Protein tyrosine phosphatase variants in human hereditary disorders and disease susceptibilities. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1673-96. [PMID: 23707412 DOI: 10.1016/j.bbadis.2013.05.022] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/14/2013] [Accepted: 05/16/2013] [Indexed: 12/18/2022]
Abstract
Reversible tyrosine phosphorylation of proteins is a key regulatory mechanism to steer normal development and physiological functioning of multicellular organisms. Phosphotyrosine dephosphorylation is exerted by members of the super-family of protein tyrosine phosphatase (PTP) enzymes and many play such essential roles that a wide variety of hereditary disorders and disease susceptibilities in man are caused by PTP alleles. More than two decades of PTP research has resulted in a collection of PTP genetic variants with corresponding consequences at the molecular, cellular and physiological level. Here we present a comprehensive overview of these PTP gene variants that have been linked to disease states in man. Although the findings have direct bearing for disease diagnostics and for research on disease etiology, more work is necessary to translate this into therapies that alleviate the burden of these hereditary disorders and disease susceptibilities in man.
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Affiliation(s)
- Wiljan J A J Hendriks
- Department of Cell Biology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Chien PN, Ryu SE. Protein Tyrosine Phosphatase σ in Proteoglycan-Mediated Neural Regeneration Regulation. Mol Neurobiol 2012; 47:220-7. [DOI: 10.1007/s12035-012-8346-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/27/2012] [Indexed: 12/25/2022]
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Bernabeu RO, Longo FM. The p75 neurotrophin receptor is expressed by adult mouse dentate progenitor cells and regulates neuronal and non-neuronal cell genesis. BMC Neurosci 2010; 11:136. [PMID: 20961458 PMCID: PMC2987811 DOI: 10.1186/1471-2202-11-136] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 10/20/2010] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The ability to regulate neurogenesis in the adult dentate gyrus will require further identification and characterization of the receptors regulating this process. In vitro and in vivo studies have demonstrated that neurotrophins and the p75 neurotrophin receptor (p75NTR) can promote neurogenesis; therefore we tested the hypothesis that p75NTR is expressed by adult dentate gyrus progenitor cells and is required for their proliferation and differentiation. RESULTS In a first series of studies focusing on proliferation, mice received a single BrdU injection and were sacrificed 2, 10 and 48 hours later. Proliferating, BrdU-positive cells were found to express p75NTR. In a second series of studies, BrdU was administered by six daily injections and mice were sacrificed 1 day later. Dentate gyrus sections demonstrated a large proportion of BrdU/p75NTR co-expressing cells expressing either the NeuN neuronal or GFAP glial marker, indicating that p75NTR expression persists at least until early stages of maturation. In p75NTR (-/-) mice, there was a 59% decrease in the number of BrdU-positive cells, with decreases in the number of BrdU cells co-labeled with NeuN, GFAP or neither marker of 35%, 60% and 64%, respectively. CONCLUSIONS These findings demonstrate that p75NTR is expressed by adult dentate progenitor cells and point to p75NTR as an important receptor promoting the proliferation and/or early maturation of not only neural, but also glial and other cell types.
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Affiliation(s)
- Ramon O Bernabeu
- Department of Neurology, UCSF/VAMC, San Francisco, CA, 94121, USA
- Institute of Cell Biology and Department of Physiology, University of Buenos Aires, Buenos Aires, Argentina
| | - Frank M Longo
- Department of Neurology and Neurological Sciences, Stanford University, Palo Alto, CA, 94035, USA
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Kondo S, Kishi H, Muraguchi A. Regulatory role of leukocyte-common-antigen-related molecule (LAR) in thymocyte differentiation. Eur J Immunol 2010; 40:1296-302. [PMID: 20186877 DOI: 10.1002/eji.200939743] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The strength of interaction between the antigenic peptide-loaded MHC (MHC/p) and the TCR determines T-cell fate in the thymus. A high avidity interaction between the TCR and the MHC/p induces apoptosis of self-reactive T cells (negative selection), whereas a moderate avidity interaction rescues thymocytes from apoptosis and permits further differentiation to mature T cells (positive selection). Leukocyte common antigen-related molecule (LAR), a receptor-like protein tyrosine phosphatase, is expressed on immature thymocytes, but its role in thymocyte differentiation has not yet been fully elucidated. We analyzed LAR-deficient mice and demonstrated that LAR deficiency affected the differentiation and expansion of immature thymocytes as well as positive and negative selection. Furthermore, LAR deficiency resulted in a lower Ca2+ response. The results indicate that LAR is an important modulator of TCR signaling that controls thymocyte differentiation.
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Affiliation(s)
- Sachiko Kondo
- Department of Immunology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
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Kwon SK, Woo J, Kim SY, Kim H, Kim E. Trans-synaptic adhesions between netrin-G ligand-3 (NGL-3) and receptor tyrosine phosphatases LAR, protein-tyrosine phosphatase delta (PTPdelta), and PTPsigma via specific domains regulate excitatory synapse formation. J Biol Chem 2010; 285:13966-78. [PMID: 20139422 PMCID: PMC2859559 DOI: 10.1074/jbc.m109.061127] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2009] [Revised: 01/12/2010] [Indexed: 01/15/2023] Open
Abstract
Synaptic cell adhesion molecules regulate various steps of synapse formation. The trans-synaptic adhesion between postsynaptic NGL-3 (for netrin-G ligand-3) and presynaptic LAR (for leukocyte antigen-related) regulates excitatory synapse formation in a bidirectional manner. However, little is known about the molecular details of the NGL-3-LAR adhesion and whether two additional LAR family proteins, protein-tyrosine phosphatase delta (PTPdelta), and PTPsigma, also interact with NGL-3 and are involved in synapse formation. We report here that the leucine-rich repeat (LRR) domain of NGL-3, containing nine LRRs, interacts with the first two fibronectin III (FNIII) domains of LAR to induce bidirectional synapse formation. Moreover, Gln-96 in the first LRR motif of NGL-3 is critical for LAR binding and induction of presynaptic differentiation. PTPdelta and PTPsigma also interact with NGL-3 via their first two FNIII domains. These two interactions promote synapse formation in a different manner; the PTPsigma-NGL-3 interaction promotes synapse formation in a bidirectional manner, whereas the PTPdelta-NGL-3 interaction instructs only presynaptic differentiation in a unidirectional manner. mRNAs encoding LAR family proteins display overlapping and differential expression patterns in various brain regions. These results suggest that trans-synaptic adhesion between NGL-3 and the three LAR family proteins regulates excitatory synapse formation in shared and distinct neural circuits.
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Affiliation(s)
- Seok-Kyu Kwon
- From the National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, and Department of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701 and
| | - Jooyeon Woo
- From the National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, and Department of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701 and
| | - Soo-Young Kim
- the Department of Anatomy and Division of Brain Korea 21 Biomedical Science, College of Medicine, Korea University, 126-1, 5-Ka, Anam-Dong, Seongbuk-Gu, Seoul 136-705, Korea
| | - Hyun Kim
- the Department of Anatomy and Division of Brain Korea 21 Biomedical Science, College of Medicine, Korea University, 126-1, 5-Ka, Anam-Dong, Seongbuk-Gu, Seoul 136-705, Korea
| | - Eunjoon Kim
- From the National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, and Department of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701 and
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Dickinson BA, Jo J, Seok H, Son GH, Whitcomb DJ, Davies CH, Sheng M, Collingridge GL, Cho K. A novel mechanism of hippocampal LTD involving muscarinic receptor-triggered interactions between AMPARs, GRIP and liprin-alpha. Mol Brain 2009; 2:18. [PMID: 19534762 PMCID: PMC2701934 DOI: 10.1186/1756-6606-2-18] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Accepted: 06/17/2009] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Long-term depression (LTD) in the hippocampus can be induced by activation of different types of G-protein coupled receptors, in particular metabotropic glutamate receptors (mGluRs) and muscarinic acetylcholine receptors (mAChRs). Since mGluRs and mAChRs activate the same G-proteins and isoforms of phospholipase C (PLC), it would be expected that these two forms of LTD utilise the same molecular mechanisms. However, we find a distinct mechanism of LTD involving GRIP and liprin-alpha. RESULTS Whilst both forms of LTD require activation of tyrosine phosphatases and involve internalisation of AMPARs, they use different molecular interactions. Specifically, mAChR-LTD, but not mGluR-LTD, is blocked by peptides that inhibit the binding of GRIP to the AMPA receptor subunit GluA2 and the binding of GRIP to liprin-alpha. Thus, different receptors that utilise the same G-proteins can regulate AMPAR trafficking and synaptic efficacy via distinct molecular mechanisms. CONCLUSION Our results suggest that mAChR-LTD selectively involves interactions between GRIP and liprin-alpha. These data indicate a novel mechanism of synaptic plasticity in which activation of M1 receptors results in AMPAR endocytosis, via a mechanism involving interactions between GluA2, GRIP and liprin-alpha.
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Affiliation(s)
- Bryony A Dickinson
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology (LINE), Faculty of Medicine and Dentistry, University of Bristol, Whitson Street, Bristol BS1 3NY, UK.
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Woo J, Kwon SK, Kim E. The NGL family of leucine-rich repeat-containing synaptic adhesion molecules. Mol Cell Neurosci 2009; 42:1-10. [PMID: 19467332 DOI: 10.1016/j.mcn.2009.05.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 05/14/2009] [Indexed: 10/20/2022] Open
Abstract
Cell adhesion molecules at neuronal synapses regulate diverse aspects of synaptic development, including axo-dendritic contact establishment, early synapse formation, and synaptic maturation. Recent studies have identified several synaptogenic adhesion molecules. The NGL (netrin-G ligand; LRRC4) family of synaptic cell adhesion molecules belongs to the superfamily of leucine-rich repeat (LRR) proteins. The three known members of the NGL family, NGL-1, NGL-2, and NGL-3, are mainly localized to the postsynaptic side of excitatory synapses, and interact with the presynaptic ligands, netrin-G1, netrin-G2, and LAR, respectively. NGLs interact with the abundant postsynaptic density (PSD) protein, PSD-95, and other postsynaptic proteins, including NMDA receptors. These interactions are thought to couple synaptic adhesion events to the assembly of synaptic proteins. In addition, NGL proteins regulate axonal outgrowth and lamina-specific dendritic segmentation, suggesting that the NGL-dependent adhesion system is important for the development of axons, dendrites, and synapses. Consistent with these functions, defects in NGLs and their ligands are associated with impaired learning and memory, hyperactivity, and an abnormal acoustic startle response in transgenic mice, and schizophrenia, bipolar disorder, and Rett syndrome in human patients.
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Affiliation(s)
- Jooyeon Woo
- National Creative Research Initiative Center for Synaptogenesis, Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
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13
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Uetani N, Bertozzi K, Chagnon MJ, Hendriks W, Tremblay ML, Bouchard M. Maturation of ureter-bladder connection in mice is controlled by LAR family receptor protein tyrosine phosphatases. J Clin Invest 2009; 119:924-35. [PMID: 19273906 DOI: 10.1172/jci37196] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 01/21/2009] [Indexed: 01/13/2023] Open
Abstract
Congenital anomalies affecting the ureter-bladder junction are frequent in newborns and are often associated with other developmental defects. However, the molecular and morphological processes underlying these malformations are still poorly defined. In this study, we identified the leukocyte antigen-related (LAR) family protein tyrosine phosphatase, receptor type, S and F (Ptprs and Ptprf [also known as Lar], respectively), as crucially important for distal ureter maturation and craniofacial morphogenesis in the mouse. Embryos lacking both Ptprs and Ptprf displayed severe urogenital malformations, characterized by hydroureter and ureterocele, and craniofacial defects such as cleft palate, micrognathia, and exencephaly. The detailed analysis of distal ureter maturation, the process by which the ureter is displaced toward its final position in the bladder wall, leads us to propose a revised model of ureter maturation in normal embryos. This process was deficient in embryos lacking Ptprs and Ptprf as a result of a marked reduction in intrinsic programmed cell death, thereby causing urogenital system malformations. In cell culture, Ptprs bound and negatively regulated the phosphorylation and signaling of the Ret receptor tyrosine kinase, whereas Ptprs-induced apoptosis was inhibited by Ret expression. Together, these results suggest that ureter positioning is controlled by the opposing actions of Ret and LAR family phosphatases regulating apoptosis-mediated tissue morphogenesis.
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Affiliation(s)
- Noriko Uetani
- Goodman Cancer Centre, Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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14
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Faux C, Hawadle M, Nixon J, Wallace A, Lee S, Murray S, Stoker A. PTPσ binds and dephosphorylates neurotrophin receptors and can suppress NGF-dependent neurite outgrowth from sensory neurons. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1689-700. [DOI: 10.1016/j.bbamcr.2007.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 06/22/2007] [Accepted: 06/25/2007] [Indexed: 12/25/2022]
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15
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Haapasalo A, Kim DY, Carey BW, Turunen MK, Pettingell WH, Kovacs DM. Presenilin/gamma-secretase-mediated cleavage regulates association of leukocyte-common antigen-related (LAR) receptor tyrosine phosphatase with beta-catenin. J Biol Chem 2007; 282:9063-72. [PMID: 17259169 DOI: 10.1074/jbc.m611324200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leukocyte-common antigen-related (LAR) receptor tyrosine phosphatase regulates cell adhesion and formation of functional synapses and neuronal networks. Here we report that LAR is sequentially cleaved by alpha- and presenilin (PS)/gamma-secretases, which also affect signaling and/or degradation of type-I membrane proteins including the Alzheimer disease-related beta-amyloid precursor protein. Similar to the previously characterized PS/gamma-secretase substrates, inhibition of gamma-secretase activity resulted in elevated LAR C-terminal fragment (LAR-CTF) levels in stably LAR-overexpressing Chinese hamster ovary (CHO) cells, human neuroglioma cells, and mouse cortical neurons endogenously expressing LAR. Furthermore, LAR-CTF levels increased in cells lacking functional PS, indicating that gamma-secretase-mediated cleavage of LAR was PS-dependent. Inhibition of alpha-secretase activity by TAPI-1 treatment blocked LAR-CTF accumulation, demonstrating that prior ectodomain shedding was prerequisite for PS/gamma-secretase-mediated cleavage of LAR. Moreover, we identified the product of PS/gamma-secretase cleavage, LAR intracellular domain (LICD), both in vitro and in cells overexpressing full-length (FL) LAR or LAR-CTFs. LAR localizes to cadherin-beta-catenin-based cellular junctions. Assembly and disassembly of these junctions are regulated by tyrosine phosphorylation. We found that endogenous tyrosine-phosphorylated beta-catenin coimmunoprecipitated with LAR in CHO cells. However, when PS/gamma-secretase activity was inhibited, the association between LAR and beta-catenin significantly diminished. In addition to cell adhesion, beta-catenin is involved in transcriptional regulation. We observed that LICD significantly decreased transcription of cyclin D1, one of the beta-catenin target genes. Thus, our results show that PS/gamma-secretase-mediated cleavage of LAR controls LAR-beta-catenin interaction, suggesting an essential role for PS/gamma-secretase in the regulation of LAR signaling.
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Affiliation(s)
- Annakaisa Haapasalo
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA
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Yang T, Massa SM, Longo FM. LAR protein tyrosine phosphatase receptor associates with TrkB and modulates neurotrophic signaling pathways. ACTA ACUST UNITED AC 2007; 66:1420-36. [PMID: 17013927 DOI: 10.1002/neu.20291] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The identities of receptor protein tyrosine phosphatases (PTPs) that associate with Trk protein tyrosine kinase (PTK) receptors and modulate neurotrophic signaling are unknown. The leukocyte common antigen-related (LAR) receptor PTP is present in neurons expressing TrkB, and like TrkB is associated with caveolae and regulates survival and neurite outgrowth. We tested the hypothesis that LAR associates with TrkB and regulates neurotrophic signaling in embryonic hippocampal neurons. Coimmunoprecipitation and coimmunostaining demonstrated LAR interaction with TrkB that is increased by BDNF exposure. BDNF neurotrophic activity was reduced in LAR-/- and LAR siRNA-treated LAR+/+ neurons and was augmented in LAR-transfected neurons. In LAR-/- neurons, BDNF-induced activation of TrkB, Shc, AKT, ERK, and CREB was significantly decreased; while in LAR-transfected neurons, BDNF-induced CREB activation was augmented. Similarly, LAR+/+ neurons treated with LAR siRNA demonstrated decreased activation of Trk and AKT. LAR is known to activate the Src PTK by dephosphorylation of its negative regulatory domain and Src transactivates Trk. In LAR-/- neurons, or neurons treated with LAR siRNA, phosphorylation of the Src regulatory domain was increased (indicating Src inactivation), consistent with a role for Src in mediating LAR's ability to up-regulate neurotrophic signaling. Interactions between LAR, TrkB, and Src were further confirmed by the findings that Src coimmunoprecipitated with LAR, that the Src inhibitor PP2 blocked the ability of LAR to augment TrkB signaling, and that siRNA-induced depletion of Src decreased LAR interaction with TrkB. These studies demonstrate that receptor PTPs can associate with Trk complexes and promote neurotrophic signaling and point to receptor PTP-based strategies as a novel approach for modulating neurotrophin function.
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MESH Headings
- Animals
- Blotting, Western/methods
- Brain-Derived Neurotrophic Factor/metabolism
- Brain-Derived Neurotrophic Factor/pharmacology
- Cell Survival/drug effects
- Cells, Cultured
- Culture Media, Conditioned/pharmacology
- Dose-Response Relationship, Drug
- Embryo, Mammalian
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/genetics
- Gene Expression Regulation/physiology
- Hippocampus/cytology
- Immunoprecipitation/methods
- Mice
- Mice, Knockout
- Mutation/physiology
- Nerve Tissue Proteins/immunology
- Nerve Tissue Proteins/physiology
- Neurons/drug effects
- Neurons/metabolism
- Phosphorylation/drug effects
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/deficiency
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/immunology
- Protein Tyrosine Phosphatases/physiology
- Pyrimidines/pharmacology
- RNA, Small Interfering/pharmacology
- Receptor, trkB/physiology
- Receptor-Like Protein Tyrosine Phosphatases, Class 2
- Receptor-Like Protein Tyrosine Phosphatases, Class 4
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/physiology
- Signal Transduction/physiology
- Time Factors
- Transfection/methods
- Tyrosine/metabolism
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Affiliation(s)
- Tao Yang
- Department of Neurology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599, USA
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17
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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] [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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18
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Uetani N, Chagnon MJ, Kennedy TE, Iwakura Y, Tremblay ML. Mammalian motoneuron axon targeting requires receptor protein tyrosine phosphatases sigma and delta. J Neurosci 2006; 26:5872-80. [PMID: 16738228 PMCID: PMC6675220 DOI: 10.1523/jneurosci.0386-06.2006] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The leukocyte common antigen-related (LAR) subfamily of receptor protein tyrosine phosphatases (RPTPs), LAR, RPTP-sigma, and RPTP-delta, regulate neuroendocrine development, axonal regeneration, and hippocampal long-term potentiation in mammals. In Drosophila, RPTPs are required for appropriate axon targeting during embryonic development. In contrast, deletion of any one of the three LAR-RPTP family members in mammals does not result in gross axon targeting defects. Both RPTP-sigma and RPTP-delta are highly expressed in the developing mammalian nervous system, suggesting they might be functionally redundant. To test this hypothesis, we generated RPTP-sigma and RPTP-delta (RPTP-sigma/delta) double-mutant mice. Although embryonic day 18.5 RPTP-sigma and RPTP-delta single-mutant embryos were viable, RPTP-sigma/delta double mutants were paralyzed, were never observed to draw a breath, and died shortly after cesarean section. RPTP-sigma/delta double mutants exhibit severe muscle dysgenesis and severe loss of motoneurons in the spinal cord. Detailed analysis of the projections of phrenic nerves in RPTP-sigma/delta double mutants indicated that these motoneuron axons emerge normally from the cervical spinal cord, but stall on reaching the diaphragm. Our results demonstrate that RPTP-sigma and RPTP-delta complement each other functionally during mammalian development, and reveal an essential contribution of RPTP-sigma and RPTP-delta to appropriate motoneuron axon targeting during mammalian axonogenesis.
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19
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Kirkham DL, Pacey LKK, Axford MM, Siu R, Rotin D, Doering LC. Neural stem cells from protein tyrosine phosphatase sigma knockout mice generate an altered neuronal phenotype in culture. BMC Neurosci 2006; 7:50. [PMID: 16784531 PMCID: PMC1570144 DOI: 10.1186/1471-2202-7-50] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 06/19/2006] [Indexed: 02/07/2023] Open
Abstract
Background The LAR family Protein Tyrosine Phosphatase sigma (PTPσ) has been implicated in neuroendocrine and neuronal development, and shows strong expression in specific regions within the CNS, including the subventricular zone (SVZ). We established neural stem cell cultures, grown as neurospheres, from the SVZ of PTPσ knockout mice and sibling controls to determine if PTPσ influences the generation and the phenotype of the neuronal, astrocyte and oligodendrocyte cell lineages. Results The neurospheres from the knockout mice acquired heterogeneous developmental characteristics and they showed similar morphological characteristics to the age matched siblings. Although Ptprs expression decreases as a function of developmental age in vivo, it remains high with the continual renewal and passage of the neurospheres. Stem cells, progenitors and differentiated neurons, astrocytes and oligodendrocytes all express the gene. While no apparent differences were observed in developing neurospheres or in the astrocytes and oligodendrocytes from the PTPσ knockout mice, the neuronal migration patterns and neurites were altered when studied in culture. In particular, neurons migrated farther from the neurosphere centers and the neurite outgrowth exceeded the length of the neuronal processes from age matched sibling controls. Conclusion Our results imply a specific role for PTPσ in the neuronal lineage, particularly in the form of inhibitory influences on neurite outgrowth, and demonstrate a role for tyrosine phosphatases in neuronal stem cell differentiation.
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Affiliation(s)
- David L Kirkham
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton Ontario, L8N 3Z5, Canada
| | - Laura KK Pacey
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton Ontario, L8N 3Z5, Canada
| | - Michelle M Axford
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton Ontario, L8N 3Z5, Canada
| | - Roberta Siu
- Cell Biology Program, The Hospital for Sick Children and Department of Biochemistry, University of Toronto, Toronto, Ontario, M5G 1X8, Canada
| | - Daniela Rotin
- Cell Biology Program, The Hospital for Sick Children and Department of Biochemistry, University of Toronto, Toronto, Ontario, M5G 1X8, Canada
| | - Laurie C Doering
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton Ontario, L8N 3Z5, Canada
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20
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Bernabeu R, Yang T, Xie Y, Mehta B, Ma SY, Longo FM. Downregulation of the LAR protein tyrosine phosphatase receptor is associated with increased dentate gyrus neurogenesis and an increased number of granule cell layer neurons. Mol Cell Neurosci 2006; 31:723-38. [PMID: 16488625 DOI: 10.1016/j.mcn.2006.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 12/16/2005] [Accepted: 01/03/2006] [Indexed: 11/18/2022] Open
Abstract
Growth factors stimulating neurogenesis act through protein tyrosine kinases which are counterbalanced by protein tyrosine phosphatases (PTPs); thus, downregulation of progenitor PTP function might provide a novel strategy for promoting neurogenesis. We tested the hypotheses that the leukocyte common antigen-related (LAR) PTP is present in adult dentate gyrus progenitors, and that its downregulation would promote neurogenesis. In adult mice, LAR immunostaining was present in Ki-67- and PCNA-positive subgranular zone cells. At 1 h post-BrdU administration, LAR-/- mice demonstrated an approximately 3-fold increase in BrdU- and PCNA-positive cells, indicating increased progenitor proliferation. At 1 day and 4 weeks following 6 days of BrdU administration, LAR-/- mice exhibited a significant increase in BrdU and NeuN colabeled cells consistent with increased neurogenesis. In association with increased neurogenesis in LAR-/- mice, stereological analysis revealed a significant 37% increase in the number of neurons present in the granule cell layer. In cultured progenitor clones derived from LAR+/+ mice, LAR immunostaining was present in PCNA- and BrdU-positive cells. Progenitor clones derived from adult LAR-/- hippocampus or LAR+/+ clones made LAR-deficient with LAR siRNA demonstrated increased proliferation and, under differentiation conditions, increased proportions of Tuj1- and MAP2-positive cells. These studies introduce LAR as the first PTP found to be expressed in dentate progenitors and point to inhibition of LAR as a potential strategy for promoting neurogenesis. These findings also provide a rare in vivo demonstration of an association between increased dentate neurogenesis and an expanded population of granule cell layer neurons.
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Affiliation(s)
- Ramon Bernabeu
- UNC School of Medicine, Department of Neurology CB7025, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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21
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Yang T, Yin W, Derevyanny VD, Moore LA, Longo FM. Identification of an ectodomain within the LAR protein tyrosine phosphatase receptor that binds homophilically and activates signalling pathways promoting neurite outgrowth. Eur J Neurosci 2006; 22:2159-70. [PMID: 16262654 DOI: 10.1111/j.1460-9568.2005.04403.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Elucidation of mechanisms by which receptor protein tyrosine phosphatases (PTPs) regulate neurite outgrowth will require characterization of ligand-receptor interactions and identification of ligand-induced signalling components mediating neurite outgrowth. The first identified ligand of the leucocyte common antigen-related (LAR) receptor PTP consists of a 99-residue ectodomain isoform, termed LARFN5C, which undergoes homophilic binding to LAR and promotes neurite outgrowth. We employed peptide mapping of LARFN5C to identify an active neurite-promoting domain of LAR. A peptide mimetic consisting of 37 residues (L59) and corresponding to the fifth LAR fibronectin type III (FNIII) domain prevented LARFN5C homophilic binding, demonstrated homophilic binding to itself and promoted neurite outgrowth of mouse E16-17 hippocampal neurons and of dorsal root ganglia explants. Response to L59 was partially lost when using neurons derived from LAR-deficient (-/-) mice or neurons treated with LAR siRNA, consistent with homophilic interaction of L59 with LAR. L59 neurite-promoting activity was decreased in the presence of inhibitors of Src, Trk, PLCgamma, PKC, PI3K and MAPK. L59 activated Src (a known substrate of LAR), FAK and TrkB and also activated downstream signalling intermediates including PKC, ERK, AKT and CREB. BDNF augmented the maximal neurite-promoting activity of L59, a finding consistent with the presence of shared and distinct signalling pathways activated by L59 with BDNF and L59 with TrkB. These studies are the first to identify an ectodomain of LAR (located within the fifth FNIII domain) capable of promoting neurite outgrowth and point to novel approaches for promotion of neurite outgrowth.
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Affiliation(s)
- Tao Yang
- Department of Neurology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
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22
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Lorber B, Hendriks WJAJ, Van der Zee CEEM, Berry M, Logan A. Effects of LAR and PTP-BL phosphatase deficiency on adult mouse retinal cells activated by lens injury. Eur J Neurosci 2005; 21:2375-83. [PMID: 15932596 DOI: 10.1111/j.1460-9568.2005.04065.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using intact and lens-lesioned wildtype, leucocyte common antigen-related phosphatase deficient (LARDeltaP) and protein tyrosine phosphatase (PTP)-BAS-like phosphatase deficient (PTP-BLDeltaP) mice, we have evaluated the role of LAR and PTP-BL in retinal ganglion cell survival and neuritogenesis, and survival of activated retinal glia in vitro. There were no differences in in vitro retinal ganglion cell neuritogenesis and survival, as well as in activated retinal glia survival between intact wildtype and intact LARDeltaP or PTP-BLDeltaP mutant mice. In wildtype, LARDeltaP, and PTP-BLDeltaP retinal cultures, pre-conditioning by lens injury significantly increased retinal ganglion cell neuritogenesis and activated retinal glia numbers. However, in retinal cultures from lens-lesioned LARDeltaP and PTP-BLDeltaP mice, significantly smaller percentages of retinal ganglion cells grew neurites compared to lens-lesioned wildtype cultures. Significantly increased numbers of retinal ganglion cells survived in retinal cultures from lens-lesioned LARDeltaP mice compared to lens-lesioned wildtypes. PTP-BL phosphatase deficiency did not affect retinal ganglion cell survival in retinal cultures from lens-lesioned mice, though activated retinal glia numbers were significantly reduced in cultures from lens-lesioned PTP-BLDeltaP mice compared to lens-lesioned wildtypes. In summary, a functional phenotype was found in LARDeltaP and PTP-BLDeltaP mice, that was only obvious in lens lesion-stimulated retinal cultures. These observations suggest that LAR enhances retinal ganglion cell neurite initiation whilst suppressing retinal ganglion cell survival, and that PTP-BL facilitates both retinal ganglion cell neurite initiation and survival of activated retinal glia.
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Affiliation(s)
- Barbara Lorber
- Molecular Neuroscience Group, Department of Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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23
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Lorber B, Berry M, Hendriks W, den Hertog J, Pulido R, Logan A. Stimulated regeneration of the crushed adult rat optic nerve correlates with attenuated expression of the protein tyrosine phosphatases RPTPalpha, STEP, and LAR. Mol Cell Neurosci 2005; 27:404-16. [PMID: 15555919 DOI: 10.1016/j.mcn.2004.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Revised: 04/07/2004] [Accepted: 06/23/2004] [Indexed: 11/25/2022] Open
Abstract
We have evaluated the spatial and temporal expression patterns of three protein tyrosine phosphatases (PTPs), receptor PTPalpha (RPTPalpha), striatal enriched phosphatase (STEP), and leucocyte common antigen-related phosphatase (LAR), in the retina and optic nerve (ON) of adult rats in which the crushed ON was either regenerating after retinal ganglion cell (RGC) stimulation with intravitreal peripheral nerve (PN) grafting or lens injury (LI), or not regenerating (no treatment). In intact adult rats, all three PTPs were expressed by RGCs and ON glia. In both the regenerating and non-regenerating models, a postlesion rise in RPTPalpha, STEP, and LAR expression occurred in the RGC somata and in the ON. However, for RPTPalpha and LAR in the RGCs, and for RPTPalpha, STEP, and LAR in the ON, this postlesion increase was attenuated in the regenerating versus the non-regenerating models. ON PTP expression changes were localized to glia in the proximal and distal stumps, and to macrophages and extracellular matrix of the glial scar at the lesion site. Interestingly, neither RPTPalpha, STEP, nor LAR localized to intact or regenerating axons. One explanation of these findings is that RPTPalpha and LAR may modulate RGC survival, and that RPTPalpha, STEP, and LAR may modulate axon growth.
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Affiliation(s)
- Barbara Lorber
- Molecular Neuroscience, Department of Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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24
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Kolkman MJM, Streijger F, Linkels M, Bloemen M, Heeren DJ, Hendriks WJAJ, Van der Zee CEEM. Mice lacking leukocyte common antigen-related (LAR) protein tyrosine phosphatase domains demonstrate spatial learning impairment in the two-trial water maze and hyperactivity in multiple behavioural tests. Behav Brain Res 2004; 154:171-82. [PMID: 15302123 DOI: 10.1016/j.bbr.2004.02.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2003] [Revised: 02/05/2004] [Accepted: 02/06/2004] [Indexed: 12/11/2022]
Abstract
Leukocyte common antigen-related (LAR) protein is a cell adhesion molecule-like receptor-type protein tyrosine phosphatase. We previously reported that in LAR tyrosine phosphatase-deficient (LAR-Delta P) mice the number and size of basal forebrain cholinergic neurons as well as their innervation of the hippocampal area was reduced. With the hippocampus being implicated in behavioural activity aspects, including learning and memory processes, we assessed possible phenotypic consequences of LAR phosphatase deficiency using a battery of rodent behaviour tests. Motor function and co-ordination tests as well as spatial learning ability assays did not reveal any performance differences between wildtype and LAR-Delta P mice. A spatial learning impairment was found in the difficult variant of the Morris water maze. Exploration, nestbuilding and activity tests indicated that LAR-Delta P mice were more active than wildtype littermates. The observed hyperactivity in LAR-Delta P mice could not be explained by altered anxiety or curiosity levels, and was found to be persistent throughout the nocturnal period. In conclusion, behavioural testing of the LAR-Delta P mice revealed a spatial learning impairment and a significant increase in activity.
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Affiliation(s)
- Marloes J M Kolkman
- Department of Cell Biology, Nijmegen Center for Molecular Life Sciences, UMC St. Radboud, University of Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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25
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Chagnon MJ, Uetani N, Tremblay ML. Functional significance of the LAR receptor protein tyrosine phosphatase family in development and diseases. Biochem Cell Biol 2004; 82:664-75. [PMID: 15674434 DOI: 10.1139/o04-120] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The protein tyrosine phosphatases (PTPs) have emerged as critical players in diverse cellular functions. The focus of this review is the leukocyte common antigen-related (LAR) subfamily of receptor PTPs (RPTPs). This subfamily is composed of three vertebrate homologs, LAR, RPTP-sigma, and RPTP-delta, as well as few invertebrates orthologs such as Dlar. LAR-RPTPs have a predominant function in nervous system development that is conserved throughout evolution. Proteolytic cleavage of LAR-RPTP proproteins results in the noncovalent association of an extracellular domain resembling cell adhesion molecules and intracellular tandem PTPs domains, which is likely regulated via dimerization. Their receptor-like structures allow them to sense the extracellular environment and transduce signals intracellularly via their cytosolic PTP domains. Although many interacting partners of the LAR-RPTPs have been identified and suggest a role for the LAR-RPTPs in actin remodeling, very little is known about the mechanisms of action of RPTPs. LAR-RPTPs recently raised a lot of interest when they were shown to regulate neurite growth and nerve regeneration in transgenic animal models. In addition, LAR-RPTPs have also been implicated in metabolic regulation and cancer. This RPTP subfamily is likely to become important as drug targets in these various human pathologies, but further understanding of their complex signal transduction cascades will be required.Key words: protein tyrosine phosphatase, LAR, signal transduction, nervous system development.
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Affiliation(s)
- Mélanie J Chagnon
- McGill Cancer Centre and Department of Biochemistry, McGill University, McIntyre Medical Sciences Building, 3655 Promenade Sir-William-Osler, Room 701, Montréal, QC H3G 1Y6, Canada
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26
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Bernier M. Protein tyrosine phosphatases. Cell Biochem Biophys 2004. [DOI: 10.1385/cbb:40:3:209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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27
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Protein tyrosine phosphatases. Cell Biochem Biophys 2004. [DOI: 10.1007/bf02739025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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Leukocyte antigen-related protein tyrosine phosphatase receptor: a small ectodomain isoform functions as a homophilic ligand and promotes neurite outgrowth. J Neurosci 2003. [PMID: 12716943 DOI: 10.1523/jneurosci.23-08-03353.2003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The identities of ligands interacting with protein tyrosine phosphatase (PTP) receptors to regulate neurite outgrowth remain mainly unknown. Analysis of cDNA and genomic clones encoding the rat leukocyte common antigen-related (LAR) PTP receptor predicted a small, approximately 11 kDa ectodomain isoform, designated LARFN5C, containing a novel N terminal followed by a C-terminal segment of the LAR fifth fibronectin type III domain. RT-PCR and Northern blot analysis confirmed the presence of LARFN5C transcripts in brain. Transfection of COS cells with LARFN5C-Fc cDNA resulted in expression of the predicted protein, and Western blot analysis verified expression of approximately 11 kDa LARFN5C protein in vivo and its developmental regulation. Beads coated with rLARFN5C demonstrated aggregation consistent with homophilic binding, and pull-down and immunoprecipitation assays demonstrated that rLARFN5C associates with the LAR receptor. rLARFN5C binding to COS cells was dependent on LAR expression, and rLARFN5C binding to LAR +/+ hippocampal neurons was fivefold greater than that found by using LAR-deficient (-/-) neurons. Substratum-bound rLARFN5C had potent neurite-promoting effects on LAR +/+ neurons, with a fivefold loss in potency with the use of LAR -/- neurons. rLARFN5C in solution at low nanomolar concentrations inhibited neurite outgrowth induced by substratum-bound rLARFN5C, consistent with receptor-based function. These studies suggest that a small ectodomain isoform of a PTP receptor can function as a ligand for the same receptor to promote neurite outgrowth.
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29
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Van der Zee CEEM, Man TY, Van Lieshout EMM, Van der Heijden I, Van Bree M, Hendriks WJAJ. Delayed peripheral nerve regeneration and central nervous system collateral sprouting in leucocyte common antigen-related protein tyrosine phosphatase-deficient mice. Eur J Neurosci 2003; 17:991-1005. [PMID: 12653975 DOI: 10.1046/j.1460-9568.2003.02516.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cell adhesion molecule-like receptor-type protein tyrosine phosphatases have been shown to be important for neurite outgrowth and neural development in several animal models. We have previously reported that in leucocyte common antigen-related (LAR) phosphatase deficient (LAR-deltaP) mice the number and size of basal forebrain cholinergic neurons, and their innervation of the hippocampal area, is reduced. In this study we compared the sprouting response of LAR-deficient and wildtype neurons in a peripheral and a central nervous system lesion model. Following sciatic nerve crush lesion, LAR-deltaP mice showed a delayed recovery of sensory, but not of motor, nerve function. In line with this, neurofilament-200 immunostaining revealed a significant reduction in the number of newly outgrowing nerve sprouts in LAR-deltaP animals. Morphometric analysis indicated decreased axonal areas in regenerating LAR-deltaP nerves when compared to wildtypes. Nonlesioned nerves in wildtype and LAR-deltaP mice did not differ regarding myelin and axon areas. Entorhinal cortex lesion resulted in collateral sprouting of septohippocampal cholinergic fibres into the dentate gyrus outer molecular layer in both genotype groups. However, LAR-deltaP mice demonstrated less increase in acetylcholinesterase density and fibre number at several time points following the lesion, indicating a delayed collateral sprouting response. Interestingly, a lesion-induced reduction in number of (septo-entorhinal) basal forebrain choline acetyltransferase-positive neurons occurred in both groups, whereas in LAR-deltaP mice the average cell body size was reduced as well. Thus, regenerative and collateral sprouting is significantly delayed in LAR-deficient mice, reflecting an important facilitative role for LAR in peripheral and central nervous system axonal outgrowth.
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Affiliation(s)
- C E E M Van der Zee
- Department of Cell Biology, Nijmegen Center for Molecular Life Sciences, UMC Radboud, University of Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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30
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Dilaver G, Schepens J, van den Maagdenberg A, Wijers M, Pepers B, Fransen J, Hendriks W. Colocalisation of the protein tyrosine phosphatases PTP-SL and PTPBR7 with beta4-adaptin in neuronal cells. Histochem Cell Biol 2003; 119:1-13. [PMID: 12548400 DOI: 10.1007/s00418-002-0489-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2002] [Indexed: 12/30/2022]
Abstract
The mouse gene Ptprr encodes the neuronal protein tyrosine phosphatases PTP-SL and PTPBR7. These proteins differ in their N-terminal domains, with PTP-SL being a cytosolic, membrane-associated phosphatase and PTPBR7 a type I transmembrane protein. In this study, we further explored the nature of the PTP-SL-associated vesicles in neuronal cells using a panel of organelle markers and noted a comparable subcellular distribution for PTP-SL and the beta4-adaptin subunit of the AP4 complex. PTP-SL, PTPBR7 and beta4-adaptin are localised at the Golgi apparatus and at vesicles throughout the cytoplasm. Immunohistochemical analysis demonstrated that PTP-SL, PTPBR7 and beta4-adaptin are all endogenously expressed in brain. Interestingly, coexpression of PTP-SL and beta4-adaptin leads to an altered subcellular localisation for PTP-SL. Instead of the Golgi and vesicle-type staining pattern, still observable for beta4-adaptin, PTP-SL is now distributed throughout the cytoplasm. Although beta4-adaptin was found to interact with the phosphatase domain of PTP-SL and PTPBR7 in the yeast two-hybrid system, it failed to do so in transfected neuronal cells. Our data suggest that the tyrosine phosphatases PTP-SL and PTPBR7 may be involved in the formation and transport of AP4-coated vesicles or in the dephosphorylation of their transmembrane cargo molecules at or near the Golgi apparatus.
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Affiliation(s)
- Gönül Dilaver
- Department of Cell Biology, Nijmegen Center for Molecular Life Sciences, University Medical Center St. Radboud, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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31
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Batt J, Cutz E, Fladd C, Rotin D. Apparent normal lung architecture in protein tyrosine phosphatase-sigma-deficient mice. Am J Physiol Lung Cell Mol Physiol 2003; 284:L214-23. [PMID: 12471016 DOI: 10.1152/ajplung.00069.2002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Protein tyrosine phosphatase-sigma (PTP-sigma) is a member of the mammalian LAR family of phosphatases, which is characterized by a cell adhesion-like ectodomain, a single transmembrane segment, and two tandemly repeated intracellular catalytic domains. The expression of PTP-sigma is developmentally regulated in epithelial, neuronal, and neuroendocrine tissues. We previously showed that PTP-sigma is strongly expressed within the fetal, but not adult, rat lung and is localized to the Clara cells and type II pneumocytes. In view of the developmentally regulated pulmonary expression of PTP-sigma, we performed a detailed histological and ultrastructural study of the lungs of PTP-sigma knockout mice we have generated. Our findings indicate no apparent structural abnormalities in the lungs of PTP-sigma-/- mice, including airway and alveolar epithelium. In addition, pulmonary neuroendocrine cells also appear normal, in contrast to pituitary, pancreatic, and gastrointestinal endocrine cells, in the knockout mice, suggesting different developmental regulation of these neuroendocrine cells. These observations suggest compensation for the absence of PTP-sigma during development by related family member phosphatases, such as LAR.
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Affiliation(s)
- Jane Batt
- Program in Cell Biology, The Hospital for Sick Children, and Biochemistry Department, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
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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] [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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Toda S, McGinty JF, Kalivas PW. Repeated cocaine administration alters the expression of genes in corticolimbic circuitry after a 3-week withdrawal: a DNA macroarray study. J Neurochem 2002; 82:1290-9. [PMID: 12358776 DOI: 10.1046/j.1471-4159.2002.01083.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Addiction to psychostimulants elicits behavioral and biochemical changes that are assumed to be mediated by alterations of gene expression in the brain. The changes in gene expression after 3 weeks of withdrawal from chronic cocaine treatment were evaluated in the nucleus accumbens core and shell, dorsal prefrontal cortex and caudate using a complementary DNA (cDNA) array. The level of mRNA encoded by several genes was identified as being up- or down-regulated in repeated cocaine versus saline subjects. The results from the cDNA array were subsequently confirmed at the protein level with immunoblotting. Of particular interest, parallel up-regulation in protein and mRNA was found for the adenosine A1 receptor in the accumbens core, neuroglycan C in the accumbens shell, and the GluR5 glutamate receptor subtype in dorsal prefrontal cortex. However, there was an increase in TrkB protein in the nucleus accumbens core of cocaine-treated rats without a corresponding alteration in mRNA. These changes of gene expression in corticolimbic circuitry may contribute to the psychostimulant-induced behavioral changes associated with addiction.
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Affiliation(s)
- Shigenobu Toda
- Department of Physiology and Neuroscience, Medical University of South Carolina, Charleston 29425, USA.
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Enhanced rate of nerve regeneration and directional errors after sciatic nerve injury in receptor protein tyrosine phosphatase sigma knock-out mice. J Neurosci 2002. [PMID: 12097500 DOI: 10.1523/jneurosci.22-13-05481.2002] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The receptor protein tyrosine phosphatase sigma (PTPsigma) is a member of the mammalian leukocyte common antigen-related (LAR) family. Its expression is developmentally regulated in neuronal tissues. The Drosophila homolog of the mammalian LAR family of phosphatases (DLAR) controls axon guidance during Drosophila embryogenesis. We have demonstrated previously that mice deficient in PTPsigma have CNS and peripheral nervous system abnormalities. The sciatic nerve in the PTPsigma(-/-) mice demonstrates an increased number of small diameter fibers and slower nerve conduction velocities compared with PTPsigma(+/+) or PTPsigma(+/-) controls. To study whether peripheral nerve regeneration is affected by PTPsigma activity, we assessed nerve regeneration in the PTPsigma(-/-) mouse after three standard models of sciatic nerve injury. We report that after sciatic nerve crush injury, nerve regeneration was significantly faster in the PTPsigma(-/-) animals, as determined by histologic, electrophysiologic, and neuromuscular testing. After sciatic nerve transection with immediate microsurgical repair or allografting, PTPsigma(-/-) nerve fibers demonstrated errors in directional growth compared with controls. We propose that PTPsigma regulates the axonal regeneration rate and guidance of regenerating fibers.
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Aricescu AR, McKinnell IW, Halfter W, Stoker AW. Heparan sulfate proteoglycans are ligands for receptor protein tyrosine phosphatase sigma. Mol Cell Biol 2002; 22:1881-92. [PMID: 11865065 PMCID: PMC135600 DOI: 10.1128/mcb.22.6.1881-1892.2002] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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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Cheng A, Dubé N, Gu F, Tremblay ML. Coordinated action of protein tyrosine phosphatases in insulin signal transduction. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:1050-9. [PMID: 11856336 DOI: 10.1046/j.0014-2956.2002.02756.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Insulin is the principal regulatory hormone involved in the tight regulation of fuel metabolism. In response to blood glucose levels, it is secreted by the beta cells of the pancreas and exerts its effects by binding to cell surface receptors that are present on virtually all cell types and tissues. In humans, perturbations in insulin function and/or secretion lead to diabetes mellitus, a severe disorder primarily characterized by an inability to maintain blood glucose homeostasis. Furthermore, it is estimated that 90-95% of diabetic patients exhibit resistance to insulin action. Thus an understanding of insulin signal transduction and insulin resistance at the molecular level is crucial to the understanding of the pathogenesis of this disease. The insulin receptor (IR) is a transmembrane tyrosine kinase that becomes activated upon ligand binding. Consequently, the receptor and its downstream substrates become tyrosine phosphorylated. This activates a series of intracellular signaling cascades which coordinately initiate the appropriate biological response. One important mechanism by which insulin signaling is regulated involves the protein tyrosine phosphatases (PTPs), which may either act on the IR itself and/or its substrates. Two well characterized examples include leuckocyte antigen related (LAR) and protein tyrosine phosphatase-1B (PTP-1B). The present review will discuss the current knowledge of these two and other potential PTPs involved in the insulin signaling pathway.
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Affiliation(s)
- Alan Cheng
- Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec, Canada
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37
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The leukocyte common antigen-related protein tyrosine phosphatase receptor regulates regenerative neurite outgrowth in vivo. J Neurosci 2001. [PMID: 11438588 DOI: 10.1523/jneurosci.21-14-05130.2001] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Drosophila and leech models of nervous system development demonstrate that protein tyrosine phosphatase (PTP) receptors regulate developmental neurite outgrowth. Whether PTP receptors regulate neurite outgrowth in adult systems or in regenerative states remains unknown. The leukocyte common antigen-related (LAR) receptor is known to be present in rodent dorsal root ganglion (DRG) neurons; therefore, the well established model of postcrush sciatic nerve regeneration was used to test the hypothesis that LAR is required for neurite outgrowth in the adult mammalian nervous system. In uninjured sciatic nerves, no differences in nerve morphology and sensory function were detected between wild-type and LAR-deficient littermate transgenic mice. Sciatic nerve crush resulted in increased LAR protein expression in DRG neurons. In addition, nerve injury led to an increase in the proportion of LAR protein isoforms known to have increased binding affinity to neurite-promoting laminin-nidogen complexes. Two weeks after nerve crush, morphological analysis of distal nerve segments in LAR-deficient transgenic mice demonstrated significantly decreased densities of myelinated fibers, decreased axonal areas, and increased myelin/axon area ratios compared with littermate controls. Electron microscopy analysis revealed a significant twofold reduction in the density of regenerating unmyelinated fibers in LAR-/- nerves distal to the crush site. Sensory testing at the 2 week time point revealed a corresponding 3 mm lag in the proximal-to-distal progression of functioning sensory fibers along the distal nerve segment. These studies introduce PTP receptors as a major new gene family regulating regenerative neurite outgrowth in vivo in the adult mammalian system.
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