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Srinivasan S, Mahowald AP, Fuller MT. The receptor tyrosine phosphatase Lar regulates adhesion between Drosophila male germline stem cells and the niche. Development 2012; 139:1381-90. [PMID: 22378638 DOI: 10.1242/dev.070052] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The stem cell niche provides a supportive microenvironment to maintain adult stem cells in their undifferentiated state. Adhesion between adult stem cells and niche cells or the local basement membrane ensures retention of stem cells in the niche environment. Drosophila male germline stem cells (GSCs) attach to somatic hub cells, a component of their niche, through E-cadherin-mediated adherens junctions, and orient their centrosomes toward these localized junctional complexes to carry out asymmetric divisions. Here we show that the transmembrane receptor tyrosine phosphatase Leukocyte-antigen-related-like (Lar), which is best known for its function in axonal migration and synapse morphogenesis in the nervous system, helps maintain GSCs at the hub by promoting E-cadherin-based adhesion between hub cells and GSCs. Lar is expressed in GSCs and early spermatogonial cells and localizes to the hub-GSC interface. Loss of Lar function resulted in a reduced number of GSCs at the hub. Lar function was required cell-autonomously in germ cells for proper localization of Adenomatous polyposis coli 2 and E-cadherin at the hub-GSC interface and for the proper orientation of centrosomes in GSCs. Ultrastructural analysis revealed that in Lar mutants the adherens junctions between hub cells and GSCs lack the characteristic dense staining seen in wild-type controls. Thus, the Lar receptor tyrosine phosphatase appears to polarize and retain GSCs through maintenance of localized E-cadherin-based adherens junctions.
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Affiliation(s)
- Shrividhya Srinivasan
- Department of Developmental Biology, Stanford University, School of Medicine, Stanford, CA 94305, USA
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Meriaux C, Arafah K, Tasiemski A, Wisztorski M, Bruand J, Boidin-Wichlacz C, Desmons A, Debois D, Laprévote O, Brunelle A, Gaasterland T, Macagno E, Fournier I, Salzet M. Multiple changes in peptide and lipid expression associated with regeneration in the nervous system of the medicinal leech. PLoS One 2011; 6:e18359. [PMID: 21526169 PMCID: PMC3081291 DOI: 10.1371/journal.pone.0018359] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 02/28/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The adult medicinal leech central nervous system (CNS) is capable of regenerating specific synaptic circuitry after a mechanical lesion, displaying evidence of anatomical repair within a few days and functional recovery within a few weeks. In the present work, spatiotemporal changes in molecular distributions during this phenomenon are explored. Moreover, the hypothesis that neural regeneration involves some molecular factors initially employed during embryonic neural development is tested. RESULTS Imaging mass spectrometry coupled to peptidomic and lipidomic methodologies allowed the selection of molecules whose spatiotemporal pattern of expression was of potential interest. The identification of peptides was aided by comparing MS/MS spectra obtained for the peptidome extracted from embryonic and adult tissues to leech transcriptome and genome databases. Through the parallel use of a classical lipidomic approach and secondary ion mass spectrometry, specific lipids, including cannabinoids, gangliosides and several other types, were detected in adult ganglia following mechanical damage to connected nerves. These observations motivated a search for possible effects of cannabinoids on neurite outgrowth. Exposing nervous tissues to Transient Receptor Potential Vanilloid (TRPV) receptor agonists resulted in enhanced neurite outgrowth from a cut nerve, while exposure to antagonists blocked such outgrowth. CONCLUSION The experiments on the regenerating adult leech CNS reported here provide direct evidence of increased titers of proteins that are thought to play important roles in early stages of neural development. Our data further suggest that endocannabinoids also play key roles in CNS regeneration, mediated through the activation of leech TRPVs, as a thorough search of leech genome databases failed to reveal any leech orthologs of the mammalian cannabinoid receptors but revealed putative TRPVs. In sum, our observations identify a number of lipids and proteins that may contribute to different aspects of the complex phenomenon of leech nerve regeneration, establishing an important base for future functional assays.
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Affiliation(s)
- Céline Meriaux
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Karim Arafah
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Aurélie Tasiemski
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Maxence Wisztorski
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Jocelyne Bruand
- Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Céline Boidin-Wichlacz
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Annie Desmons
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Delphine Debois
- Institut de Chimie des Substances Naturelles, Centre de Recherche de Gif, Gif-sur-Yvette, France
| | - Olivier Laprévote
- Institut de Chimie des Substances Naturelles, Centre de Recherche de Gif, Gif-sur-Yvette, France
- Chimie Toxicologie Analytique et Cellulaire, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Paris, France
| | - Alain Brunelle
- Institut de Chimie des Substances Naturelles, Centre de Recherche de Gif, Gif-sur-Yvette, France
| | - Terry Gaasterland
- Marine Biology Research Division, Scripps Institution of Oceanography, Division of Biological Sciences, Institute of Genomic Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Eduardo Macagno
- Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Isabelle Fournier
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
| | - Michel Salzet
- Université Lille Nord de France, Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée (FABMS), EA 4550, Université Lille 1, Villeneuve d'Ascq, France
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Sethi J, Zhao B, Cuvillier-Hot V, Boidin-Wichlacz C, Salzet M, Macagno ER, Baker MW. The receptor protein tyrosine phosphatase HmLAR1 is up-regulated in the CNS of the adult medicinal leech following injury and is required for neuronal sprouting and regeneration. Mol Cell Neurosci 2010; 45:430-8. [PMID: 20708686 DOI: 10.1016/j.mcn.2010.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 07/16/2010] [Accepted: 08/01/2010] [Indexed: 01/19/2023] Open
Abstract
LAR-like receptor protein tyrosine phosphatases (RPTPs), which are abundantly expressed in the nervous systems of most if not all bilaterian animals thus far examined, have been implicated in regulating a variety of critical neuronal processes. These include neuronal pathfinding, adhesion and synaptogenesis during development and, in adult mammals, neuronal regeneration. Here we explored a possible role of a LAR-like RPTP (HmLAR1) in response to mechanical trauma in the adult nervous system of the medicinal leech. In situ hybridization and QPCR analyses of HmLAR1 expression in individual segmental ganglia revealed a significant up-regulation in receptor expression following CNS injury, both in situ and following a period in vitro. Furthermore, we observed up-regulation in the expression of the leech homologue of the Abelson tyrosine kinase, a putative signaling partner to LAR receptors, but not among other tyrosine kinases. The effects on neuronal regeneration were assayed by comparing growth across a nerve crush by projections of individual dorsal P neurons (P(D)) following single-cell injection of interfering RNAs against the receptor or control RNAs. Receptor RNAi led to a significant reduction in HmLAR1 expression by the injected cells and resulted in a significant decrease in sprouting and regenerative growth at the crush site relative to controls. These studies extend the role of the HmLARs from leech neuronal development to adult neuronal regeneration and provide a platform to investigate neuronal regeneration and gene regulation at the single cell level.
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Affiliation(s)
- Jasmine Sethi
- Division of Biology, University of California, San Diego, CA 92093, USA
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Baker MW, Macagno ER. Expression levels of a LAR-like receptor protein tyrosine phosphatase correlate with neuronal branching and arbor density in the medicinal leech. Dev Biol 2010; 344:346-57. [PMID: 20541541 DOI: 10.1016/j.ydbio.2010.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 05/28/2010] [Accepted: 06/03/2010] [Indexed: 12/24/2022]
Abstract
LAR-like receptor protein tyrosine phosphatases (RPTPs), which are reported to be highly expressed in the nervous systems of most bilaterian animals, have been implicated in the regulation of critical developmental processes, such as neuronal pathfinding, cell adhesion and synaptogenesis. Here we report that two LAR-like RPTPs in the medicinal leech, HmLAR1 and HmLAR2, play roles in regulating the size and density of neuronal arbors within the developing nervous system and in the body wall. Employing single-cell RNAi knockdown and transgene expression techniques, we demonstrate that the expression level of HmLAR1 is directly correlated with the density of an identified neuron's arborization. Knocking down HmLAR1 mRNA levels in the mechanosensory pressure (P) neurons produces a reduced central arbor and a smaller arbor in the peripheral body wall, with fewer terminal branches. By contrast, overexpression of this receptor in a P cell leads to extensive neuronal sprouting, including many supernumerary neurites and terminal branches as well as, in some instances, the normal monopolar morphology of the P cell becoming multipolar. We also report that induced neuronal sprouting requires the expression of the receptor's membrane tethered ectodomain, including the NH(2)-Ig domains, but not of the intracellular phosphatase domains of the receptor. Interestingly, sprouting could be elicited upon ectopic expression of HmLAR1 and the related RPTP, HmLAR2 in the P and other neurons, including those that do not normally express either RPTP, suggesting that the substrates involved in HmLAR-induced sprouting are present in most neurons irrespective of whether they normally express these LAR-like RPTPs. Our data are consistent with the hypothesis that the receptors' ectodomains promote an adhesive interaction that enhances the maintenance of new processes.
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Affiliation(s)
- Michael W Baker
- Division of Biology, University of California, San Diego, CA 92093, USA.
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Baker MW, Peterson SM, Macagno ER. The receptor phosphatase HmLAR2 collaborates with focal adhesion proteins in filopodial tips to control growth cone morphology. Dev Biol 2008; 320:215-25. [PMID: 18582860 DOI: 10.1016/j.ydbio.2008.05.522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 05/05/2008] [Accepted: 05/06/2008] [Indexed: 01/15/2023]
Abstract
Receptor protein tyrosine phosphatases (RPTPs) have been shown to play key roles in regulating axon guidance and synaptogenesis. HmLAR2, one of two closely related LAR-like RPTPs in the embryonic leech, is expressed in a few central neurons and in a unique segmentally-iterated peripheral cell, the comb cell (CC). Here we show that tagged HmLAR2-EGFP has a punctate pattern of expression in the growth cones of the CC, particularly at the tips of extending filopodia. Moreover, although expression of the wild-type EGFP-tagged receptor does not affect CC growth cone morphology, expression of a putative dominant-negative mutant of the receptor, CS-HmLAR2, leads to the enlargement of the growth cones, a shortening of filopodia, and errors in cellular tiling. RNAi of several candidate substrate signaling proteins, Lena (leech Ena/Vasp), beta-integrin and paxillin, but not beta-catenin, phenocopies particular aspects of the effects of HmLAR2 RNAi. For paxillin, which co-localizes with HmLAR2 at growth cone puncta, knock-down led to a reduction in the number of such puncta. Together, our data suggests that HmLAR2 regulates the morphology of the growth cone by controlling F-actin polymerization and focal adhesion complexes.
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Affiliation(s)
- Michael W Baker
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA.
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Lambert JD. Mesoderm in spiralians: the organizer and the 4d cell. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2008; 310:15-23. [PMID: 17577229 DOI: 10.1002/jez.b.21176] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Spiralia is a clade of protostome invertebrate phyla that share a highly conserved mode of early development. Spiralian development is characterized by regularities in the arrangement of early cleavages, the fates of the cells that are produced by these divisions, and the development of the distinctive trochophore larva. Because of the strong conservation in early development, homologies can be identified between cells in divergent taxa. Some of the most striking examples of conservation in the spiralian embryo are in the cells that generate the mesoderm. The specification of the mesodermal precursors has been well characterized by embryological approaches, and recently the molecular mechanisms of mesoderm specification are starting to be elucidated. This review examines the development of mesoderm in spiralians in a comparative context, with particular focus on the relationship between the mesendodermal cell 4d and the embryonic organizer.
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Affiliation(s)
- J David Lambert
- Department of Biology, University of Rochester, Rochester, New York 14627, USA.
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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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Lingor P, Michel U, Bähr M. The Long Processes of Short Interfering RNAs – RNA Interference and Its Implications in Neuronal Cells. NEURODEGENER DIS 2004; 1:3-8. [PMID: 16908968 DOI: 10.1159/000076664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2003] [Accepted: 09/02/2003] [Indexed: 11/19/2022] Open
Abstract
Reverse genetics has been greatly advanced by the discovery of RNA interference (RNAi). This intracellular RNA-mediated gene silencing pathway is partially conserved from plants to mammals and offers a new powerful tool for the analysis of gene function. We give a brief overview of the discovery of RNAi, the underlying mechanisms and probable intrinsic roles of the pathway. Recent reports utilizing RNAi for gene silencing approaches in neuronal cells are reviewed and possible delivery techniques for small interfering RNA/double-stranded RNA are discussed.
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Affiliation(s)
- Paul Lingor
- S2-Laboratory, Department of Neurology, Faculty of Medicine, University of Göttingen, Göttingen, Germany.
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