1
|
Lettieri A, Oleari R, van den Munkhof MH, van Battum EY, Verhagen MG, Tacconi C, Spreafico M, Paganoni AJJ, Azzarelli R, Andre' V, Amoruso F, Palazzolo L, Eberini I, Dunkel L, Howard SR, Fantin A, Pasterkamp RJ, Cariboni A. SEMA6A drives GnRH neuron-dependent puberty onset by tuning median eminence vascular permeability. Nat Commun 2023; 14:8097. [PMID: 38062045 PMCID: PMC10703890 DOI: 10.1038/s41467-023-43820-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Innervation of the hypothalamic median eminence by Gonadotropin-Releasing Hormone (GnRH) neurons is vital to ensure puberty onset and successful reproduction. However, the molecular and cellular mechanisms underlying median eminence development and pubertal timing are incompletely understood. Here we show that Semaphorin-6A is strongly expressed by median eminence-resident oligodendrocytes positioned adjacent to GnRH neuron projections and fenestrated capillaries, and that Semaphorin-6A is required for GnRH neuron innervation and puberty onset. In vitro and in vivo experiments reveal an unexpected function for Semaphorin-6A, via its receptor Plexin-A2, in the control of median eminence vascular permeability to maintain neuroendocrine homeostasis. To support the significance of these findings in humans, we identify patients with delayed puberty carrying a novel pathogenic variant of SEMA6A. In all, our data reveal a role for Semaphorin-6A in regulating GnRH neuron patterning by tuning the median eminence vascular barrier and thereby controlling puberty onset.
Collapse
Affiliation(s)
- Antonella Lettieri
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy
- Department of Health Sciences, University of Milan, Via di Rudinì 8, 20142, Milano, Italy
| | - Roberto Oleari
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy
| | - Marleen Hester van den Munkhof
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
| | - Eljo Yvette van Battum
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
| | - Marieke Geerte Verhagen
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
- VIB-KU Leuven, Center for Brain & Disease Research, Leuven, Belgium
| | - Carlotta Tacconi
- Department of Biosciences, University of Milan, Via Celoria 26, 20133, Milan, Italy
- Division of Immunology, Transplantation, and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Marco Spreafico
- Department of Biosciences, University of Milan, Via Celoria 26, 20133, Milan, Italy
| | | | - Roberta Azzarelli
- Wellcome - Medical Research Council Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, CB2 0AW, UK
| | - Valentina Andre'
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy
| | - Federica Amoruso
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy
| | - Luca Palazzolo
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy
| | - Ivano Eberini
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy
| | - Leo Dunkel
- Centre for Endocrinology William Harvey Research Institute Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Sasha Rose Howard
- Centre for Endocrinology William Harvey Research Institute Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
- Department of Paediatric Endocrinology, Barts Health NHS Trust, London, E1 1FR, UK
| | - Alessandro Fantin
- Department of Biosciences, University of Milan, Via Celoria 26, 20133, Milan, Italy.
| | - Ronald Jeroen Pasterkamp
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
| | - Anna Cariboni
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, 20133, Milan, Italy.
| |
Collapse
|
2
|
Prieur DS, Francius C, Gaspar P, Mason CA, Rebsam A. Semaphorin-6D and Plexin-A1 Act in a Non-Cell-Autonomous Manner to Position and Target Retinal Ganglion Cell Axons. J Neurosci 2023; 43:5769-5778. [PMID: 37344233 PMCID: PMC10423046 DOI: 10.1523/jneurosci.0072-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/04/2023] [Accepted: 05/01/2023] [Indexed: 06/23/2023] Open
Abstract
Semaphorins and Plexins form ligand/receptor pairs that are crucial for a wide range of developmental processes from cell proliferation to axon guidance. The ability of semaphorins to act both as signaling receptors and ligands yields a multitude of responses. Here, we describe a novel role for Semaphorin-6D (Sema6D) and Plexin-A1 in the positioning and targeting of retinogeniculate axons. In Plexin-A1 or Sema6D mutant mice of either sex, the optic tract courses through, rather than along, the border of the dorsal lateral geniculate nucleus (dLGN), and some retinal axons ectopically arborize adjacent and lateral to the optic tract rather than defasciculating and entering the target region. We find that Sema6D and Plexin-A1 act together in a dose-dependent manner, as the number of the ectopic retinal projections is altered in proportion to the level of Sema6D or Plexin-A1 expression. Moreover, using retinal in utero electroporation of Sema6D or Plexin-A1 shRNA, we show that Sema6D and Plexin-A1 are both required in retinal ganglion cells for axon positioning and targeting. Strikingly, nonelectroporated retinal ganglion cell axons also mistarget in the tract region, indicating that Sema6D and Plexin-A1 can act non-cell-autonomously, potentially through axon-axon interactions. These data provide novel evidence for a dose-dependent and non-cell-autonomous role for Sema6D and Plexin-A1 in retinal axon organization in the optic tract and dLGN.SIGNIFICANCE STATEMENT Before innervating their central brain targets, retinal ganglion cell axons fasciculate in the optic tract and then branch and arborize in their target areas. Upon deletion of the guidance molecules Plexin-A1 or Semaphorin-6D, the optic tract becomes disorganized near and extends within the dorsal lateral geniculate nucleus. In addition, some retinal axons form ectopic aggregates within the defasciculated tract. Sema6D and Plexin-A1 act together as a receptor-ligand pair in a dose-dependent manner, and non-cell-autonomously, to produce this developmental aberration. Such a phenotype highlights an underappreciated role for axon guidance molecules in tract cohesion and appropriate defasciculation near, and arborization within, targets.
Collapse
Affiliation(s)
- Delphine S Prieur
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
| | - Cédric Francius
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
| | - Patricia Gaspar
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
| | - Carol A Mason
- Departments of Pathology and Cell Biology, Neuroscience, and Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027
| | - Alexandra Rebsam
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, F-75012, France
| |
Collapse
|
3
|
Chen G, Yan J, Fu Z. Comprehensive Analysis to Identify LINC00511-hsa-miR-625-5p-SEMA6A Pathway Fuels Progression of Skin Cutaneous Melanoma. Int J Genomics 2023; 2023:6422941. [PMID: 37434634 PMCID: PMC10332930 DOI: 10.1155/2023/6422941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 06/14/2023] [Accepted: 06/21/2023] [Indexed: 07/13/2023] Open
Abstract
Objective Skin cutaneous melanoma (SKCM) is a highly lethal malignancy that poses a significant threat to human health. Recent research has shown that competing endogenous RNA (ceRNA) regulatory networks play a critical role in the development and progression of various types of cancer, including SKCM. The objective of this study is to investigate the ceRNA regulatory network associated with the transmembrane protein semaphorin 6A (SEMA6A) and identify the underlying molecular mechanisms involved in SKCM. Methods Expression profiles of four RNAs, including pseudogenes, long non-coding RNAs, microRNAs, and mRNAs were obtained from The Cancer Genome Atlas database. The analysis was completed by bioinformatics methods, and the expression levels of the selected genes were verified by cell experiments. Results Bioinformatics analysis revealed that the LINC00511-hsa-miR-625-5p-SEMA6A ceRNA network was associated with SKCM prognosis. Furthermore, immune infiltration analysis indicated that the LINC00511-hsa-miR-625-5p-SEMA6A axis may have an impact on changes in the tumor immune microenvironment of SKCM. Conclusion The LINC00511-hsa-miR-625-5p-SEMA6A axis could be a promising therapeutic target and a prognostic biomarker for SKCM.
Collapse
Affiliation(s)
- Guanghua Chen
- Department of Dermatology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Child Infection and Immunity, Chongqing 400014, China
| | - Jia Yan
- Department of General Surgery, University-Town Hospital of Chongqing Medical University, Chongqing 401331, China
| | - Zhou Fu
- Department of Respiratory, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Child Infection and Immunity, Chongqing 400014, China
| |
Collapse
|
4
|
SEMA6A is a prognostic biomarker in glioblastoma. Tumour Biol 2015; 36:8333-40. [DOI: 10.1007/s13277-015-3584-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 05/18/2015] [Indexed: 11/26/2022] Open
|
5
|
Bernard F, Moreau-Fauvarque C, Heitz-Marchaland C, Zagar Y, Dumas L, Fouquet S, Lee X, Shao Z, Mi S, Chédotal A. Role of transmembrane semaphorin Sema6A in oligodendrocyte differentiation and myelination. Glia 2012; 60:1590-604. [DOI: 10.1002/glia.22378] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 06/05/2012] [Indexed: 11/09/2022]
|
6
|
Rogalewski A, Dittgen T, Klugmann M, Kirsch F, Krüger C, Pitzer C, Minnerup J, Schäbitz WR, Schneider A. Semaphorin 6A improves functional recovery in conjunction with motor training after cerebral ischemia. PLoS One 2010; 5:e10737. [PMID: 20505770 PMCID: PMC2873991 DOI: 10.1371/journal.pone.0010737] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 04/08/2010] [Indexed: 11/18/2022] Open
Abstract
We have previously identified Semaphorin 6a (Sema6A) as an upregulated gene product in a gene expression screen in cortical ischemia [1]. Semaphorin 6a was regulated during the recovery phase following ischemia in the cortex. Semaphorin 6a is a member of the superfamily of semaphorins involved in axon guidance and other functions. We hypothesized that the upregulation indicates a crucial role of this molecule in post-stroke rewiring of the brain. Here we have tested this hypothesis by overexpressing semaphorin 6a in the cortex by microinjection of a modified AAV2-virus. A circumscribed cortical infarct was induced, and the recovery of rats monitored for up to 4 weeks using a well-established test battery (accelerated rotarod training paradigm, cylinder test, adhesive tape removal). We observed a significant improvement in post-ischemic recovery of animals injected with the semaphorin 6a virus versus animals treated with a control virus. We conclude that semaphorin 6a overexpressed in the cortex enhances recovery after cerebral ischemia. Semaphorin 6a may represent a novel therapeutic candidate for the treatment of chronic stroke.
Collapse
Affiliation(s)
| | | | - Matthias Klugmann
- Institute for Physiological Chemistry and Pathobiochemistry, Johannes-Gutenberg-University Mainz, Mainz, Germany
| | | | | | | | - Jens Minnerup
- Department of Neurology, University of Muenster, Muenster, Germany
| | - Wolf-Rüdiger Schäbitz
- Department of Neurology, University of Muenster, Muenster, Germany
- * E-mail: (WRS); (AS)
| | - Armin Schneider
- Institute for Physiological Chemistry and Pathobiochemistry, Johannes-Gutenberg-University Mainz, Mainz, Germany
- * E-mail: (WRS); (AS)
| |
Collapse
|
7
|
Sudarov A, Joyner AL. Cerebellum morphogenesis: the foliation pattern is orchestrated by multi-cellular anchoring centers. Neural Dev 2007; 2:26. [PMID: 18053187 PMCID: PMC2246128 DOI: 10.1186/1749-8104-2-26] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Accepted: 12/03/2007] [Indexed: 11/23/2022] Open
Abstract
Background The cerebellum has a striking morphology consisting of folia separated by fissures of different lengths. Since folia in mammals likely serve as a broad platform on which the anterior-posterior organization of the sensory-motor circuits of the cerebellum are built, it is important to understand how such complex morphology arises. Results Using a combination of genetic inducible fate mapping, high-resolution cellular analysis and mutant studies in mouse, we demonstrate that a key event in initiation of foliation is the acquisition of a distinct cytoarchitecture in the regions that will become the base of each fissure. We term these regions 'anchoring centers'. We show that the first manifestation of anchoring centers when the cerebellar outer surface is smooth is an increase in proliferation and inward thickening of the granule cell precursors, which likely causes an associated slight invagination of the Purkinje cell layer. Thereafter, granule cell precursors within anchoring centers become distinctly elongated along the axis of the forming fissure. As the outer cerebellar surface begins to fold inwards, Bergmann glial fibers radiate in towards the base of the immature fissure in a fan shape. Once the anchoring center is formed, outgrowth of folia seems to proceed in a self-sustaining manner driven by granule cell migration along Bergmann glial fibers. Finally, by analyzing a cerebellum foliation mutant (Engrailed 2), we demonstrate that changing the timing of anchoring center formation leads to predictable changes in the shape and size of the surrounding folia. Conclusion We present a new cellular model of the initial formation of cerebellar fissures with granule cells providing the driving physical force. Both the precise timing of the appearance of anchoring centers at the prospective base of each fissure and the subsequent coordinated action of granule cells and Bergmann glial fibers within the anchoring centers dictates the shape of the folia.
Collapse
Affiliation(s)
- Anamaria Sudarov
- Developmental Biology Program, Sloan-Kettering Institute, York Avenue, New York, NY 10021, USA.
| | | |
Collapse
|
8
|
Mann F, Chauvet S, Rougon G. Semaphorins in development and adult brain: Implication for neurological diseases. Prog Neurobiol 2007; 82:57-79. [PMID: 17537564 DOI: 10.1016/j.pneurobio.2007.02.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 01/18/2007] [Accepted: 02/26/2007] [Indexed: 01/17/2023]
Abstract
As a group, Semaphorins are expressed in most tissues and this distribution varies considerably with age. Semaphorins are dynamically expressed during embryonic development and their expression is often associated with growing axons. This expression decreases with maturity and several observations support the idea that in adult brain the expression of secreted Semaphorins is sensitive to electrical activity and experience. The functional role of Semaphorins in guiding axonal projections is well established and more recent evidence points to additional roles in the development, function and reorganization of synaptic complexes. Semaphorins exert the majority of their effects by binding to cognate receptor proteins through their extracellular domains. A common theme is that Semaphorin-triggered signalling induces the rearrangement of the actin and microtubule cytoskeleton. Mutations in Semaphorin genes are linked to several human diseases associated with neurological changes, but their actual influence in the pathogenesis of these diseases remains to be demonstrated. In addition, Semaphorins and their receptors are likely to mediate cross-talk between neurons and other cell types, including in pathological situations where their influence can be damaging or favourable depending on the context. We discuss how the manipulation of Semaphorin function might be crucial for future clinical studies.
Collapse
Affiliation(s)
- Fanny Mann
- CNRS UMR 6216, Université de la Méditerranée, Developmental Biology Institute of Marseille Luminy, Case 907, Parc Scientifique de Luminy, 13288 Marseille Cedex 09, France
| | | | | |
Collapse
|
9
|
Abstract
Semaphorins are secreted, transmembrane, and GPI-linked proteins, defined by cysteine-rich semaphorin protein domains, that have important roles in a variety of tissues. Humans have 20 semaphorins, Drosophila has five, and two are known from DNA viruses; semaphorins are also found in nematodes and crustaceans but not in non-animals. They are grouped into eight classes on the basis of phylogenetic tree analyses and the presence of additional protein motifs. The expression of semaphorins has been described most fully in the nervous system, but they are also present in most, or perhaps all, other tissues. Functionally, semaphorins were initially characterized for their importance in the development of the nervous system and in axonal guidance. More recently, they have been found to be important for the formation and functioning of the cardiovascular, endocrine, gastrointestinal, hepatic, immune, musculoskeletal, renal, reproductive, and respiratory systems. A common theme in the mechanisms of semaphorin function is that they alter the cytoskeleton and the organization of actin filaments and the microtubule network. These effects occur primarily through binding of semaphorins to their receptors, although transmembrane semaphorins also serve as receptors themselves. The best characterized receptors for mediating semaphorin signaling are members of the neuropilin and plexin families of transmembrane proteins. Plexins, in particular, are thought to control many of the functional effects of semaphorins; the molecular mechanisms of semaphorin signaling are still poorly understood, however. Given the importance of semaphorins in a wide range of functions, including neural connectivity, angiogenesis, immunoregulation, and cancer, much remains to be learned about these proteins and their roles in pathology and human disease.
Collapse
Affiliation(s)
- Umar Yazdani
- Center for Basic Neuroscience, Department of Pharmacology, NA4.301/5323 Harry Hines Blvd, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jonathan R Terman
- Center for Basic Neuroscience, Department of Pharmacology, NA4.301/5323 Harry Hines Blvd, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| |
Collapse
|
10
|
Kerjan G, Dolan J, Haumaitre C, Schneider-Maunoury S, Fujisawa H, Mitchell KJ, Chédotal A. The transmembrane semaphorin Sema6A controls cerebellar granule cell migration. Nat Neurosci 2005; 8:1516-24. [PMID: 16205717 DOI: 10.1038/nn1555] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 08/31/2005] [Indexed: 11/08/2022]
Abstract
The transmembrane semaphorin protein Sema6A is broadly expressed in the developing nervous system. Sema6A repels several classes of developing axons in vitro and contributes to thalamocortical axon guidance in vivo. Here we show that during cerebellum development, Sema6A is selectively expressed by postmitotic granule cells during their tangential migration in the deep external granule cell layer, but not during their radial migration. In Sema6A-deficient mice, many granule cells remain ectopic in the molecular layer where they differentiate and are contacted by mossy fibers. The analysis of ectopic granule cell morphology in Sema6a-/- mice, and of granule cell migration and neurite outgrowth in cerebellar explants, suggests that Sema6A controls the initiation of granule cell radial migration, probably through a modulation of nuclear and/or soma translocation. Finally, the analysis of mouse chimeras suggests that this function of Sema6A is primarily non-cell-autonomous.
Collapse
Affiliation(s)
- Géraldine Kerjan
- Centre National de la Recherche Scientifique UMR7102, Université de Paris 6, Case 12, 9 Quai Saint-Bernard, 75005 Paris, France
| | | | | | | | | | | | | |
Collapse
|
11
|
Braquart-Varnier C, Danesin C, Clouscard-Martinato C, Agius E, Escalas N, Benazeraf B, Ai X, Emerson C, Cochard P, Soula C. A subtractive approach to characterize genes with regionalized expression in the gliogenic ventral neuroepithelium: identification of chick Sulfatase 1 as a new oligodendrocyte lineage gene. Mol Cell Neurosci 2004; 25:612-28. [PMID: 15080891 DOI: 10.1016/j.mcn.2003.11.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Revised: 11/13/2003] [Accepted: 11/20/2003] [Indexed: 11/17/2022] Open
Abstract
To address the question of the origin of glial cells and the mechanisms leading to their specification, we have sought to identify novel genes expressed in glial progenitors. We adopted suppression subtractive hybridization (SSH) to establish a chick cDNA library enriched for genes specifically expressed at 6 days of incubation (E6) in the ventral neuroepithelium, a tissue previously shown to contain glial progenitors. Screens were then undertaken to select differentially expressed cDNAs, and out of 82 unique SSH clones, 21 were confirmed to display a regionalized expression along the dorsoventral axis of the E6 ventral neuroepithelium. Among these, we identified a transcript coding for the chick orthologue of Sulf1, a recently identified cell surface sulfatase, as a new, early marker of oligodendrocyte (OL) precursors in the chick embryonic spinal cord. This study provides groundwork for the further identification of genes involved in glial specification.
Collapse
Affiliation(s)
- Christine Braquart-Varnier
- Centre de Biologie du Développement, UMR5547 CNRS/UPS, Université Paul Sabatier, 31062 Toulouse Cedex, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Toyofuku T, Zhang H, Kumanogoh A, Takegahara N, Suto F, Kamei J, Aoki K, Yabuki M, Hori M, Fujisawa H, Kikutani H. Dual roles of Sema6D in cardiac morphogenesis through region-specific association of its receptor, Plexin-A1, with off-track and vascular endothelial growth factor receptor type 2. Genes Dev 2004; 18:435-47. [PMID: 14977921 PMCID: PMC359397 DOI: 10.1101/gad.1167304] [Citation(s) in RCA: 234] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Semaphorins, originally identified as axon guidance facto s in the nervous system, play integral roles in organogenesis. Here, we demonstrate a critical involvement of Sema6D in cardiac morphogenesis. Ectopic expression of Sema6D o RNA interference against Sema6D induces expansion or narrowing of the ventricular chamber, respectively, during chick embryonic development. Sema6D also exerts region-specific activities on cardiac explants, a migration-promoting activity on outgrowing cells from the conotruncal segment, and a migration-inhibitory activity on those from the ventricle. Plexin-A1 mediates these activities as the major Sema6D-binding receptor. Plexin-A1 forms a receptor complex with vascular endothelial growth factor receptor type 2 in the conotruncal segment or with Off-track in the ventricle segment; these complexes are responsible for the effects of Sema6D on the respective regions. Thus, the differential association of Plexin-A1 with additional receptor components entitles Sema6D to exert distinct biological activities at adjacent regions. This is crucial for complex cardiac morphogenesis.
Collapse
Affiliation(s)
- Toshihiko Toyofuku
- Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Taniguchi M, Shimizu T. Characterization of a novel member of murine semaphorin family. Biochem Biophys Res Commun 2004; 314:242-8. [PMID: 14715272 DOI: 10.1016/j.bbrc.2003.12.083] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Semaphorin gene family contains a large number of secreted and transmembrane proteins, and some of them are functioning as the repulsive and attractive cues of the axon guidance during development. Here we report murine orthologues of a novel member of class 6 semaphorin gene, semaphorin 6D (Sema6D), mapped on the chromosome 2. Sema6D is mainly expressed in the brain and lung, and the ubiquitous expression in the brain continues from embryonic late stage to adulthood, as determined by Northern blot and in situ hybridization. We also found that Sema6D has five different splicing variants, and the expression patterns of individual isoforms differ depending on the tissues. Thus, Sema6D may play important roles in various functions including the axon guidance during development and neuronal plasticity.
Collapse
Affiliation(s)
- Masahiko Taniguchi
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Japan.
| | | |
Collapse
|
14
|
Judas M, Milosević NJ, Rasin MR, Heffer-Lauc M, Kostović I. Complex patterns and simple architects: molecular guidance cues for developing axonal pathways in the telencephalon. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2003; 32:1-32. [PMID: 12827969 DOI: 10.1007/978-3-642-55557-2_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- M Judas
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Salata 12, 10000 Zagreb, Croatia
| | | | | | | | | |
Collapse
|
15
|
Holtmaat AJGD, De Winter F, De Wit J, Gorter JA, da Silva FHL, Verhaagen J. Semaphorins: contributors to structural stability of hippocampal networks? PROGRESS IN BRAIN RESEARCH 2002; 138:17-38. [PMID: 12432760 DOI: 10.1016/s0079-6123(02)38068-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Anthony J G D Holtmaat
- Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ Amsterdam, The Netherlands.
| | | | | | | | | | | |
Collapse
|
16
|
Garel S, Yun K, Grosschedl R, Rubenstein JLR. The early topography of thalamocortical projections is shifted in Ebf1 and Dlx1/2 mutant mice. Development 2002; 129:5621-34. [PMID: 12421703 DOI: 10.1242/dev.00166] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The prevailing model to explain the formation of topographic projections in the nervous system stipulates that this process is governed by information located within the projecting and targeted structures. In mammals, different thalamic nuclei establish highly ordered projections with specific neocortical domains and the mechanisms controlling the initial topography of these projections remain to be characterized. To address this issue, we examined Ebf1(-/-) embryos in which a subset of thalamic axons does not reach the neocortex. We show that the projections that do form between thalamic nuclei and neocortical domains have a shifted topography, in the absence of regionalization defects in the thalamus or neocortex. This shift is first detected inside the basal ganglia, a structure on the path of thalamic axons, and which develops abnormally in Ebf1(-/-) embryos. A similar shift in the topography of thalamocortical axons inside the basal ganglia and neocortex was observed in Dlx1/2(-/-) embryos, which also have an abnormal basal ganglia development. Furthermore, Dlx1 and Dlx2 are not expressed in the dorsal thalamus or in cortical projections neurons. Thus, our study shows that: (1) different thalamic nuclei do not establish projections independently of each other; (2) a shift in thalamocortical topography can occur in the absence of major regionalization defects in the dorsal thalamus and neocortex; and (3) the basal ganglia may contain decision points for thalamic axons' pathfinding and topographic organization. These observations suggest that the topography of thalamocortical projections is not strictly determined by cues located within the neocortex and may be regulated by the relative positioning of thalamic axons inside the basal ganglia.
Collapse
Affiliation(s)
- Sonia Garel
- Nina Ireland Laboratory of Developmental Neurobiology, Department of Psychiatry, University of California San Francisco, San Francisco, CA 94143-0984, USA
| | | | | | | |
Collapse
|
17
|
Gesemann M, Litwack ED, Yee KT, Christen U, O'Leary DD. Identification of candidate genes for controlling development of the basilar pons by differential display PCR. Mol Cell Neurosci 2001; 18:1-12. [PMID: 11461149 DOI: 10.1006/mcne.2001.0996] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The basilar pons, a major hindbrain nucleus involved in sensory-motor integration, has become a model system for studying long-distance neuronal migration, axon-target recognition by collateral branching, and the formation of patterned axonal projections. To identify genes potentially involved in these developmental events, we have performed a differential display PCR screen comparing RNA isolated from the developing basilar pons with RNA obtained from developing cerebellum and olfactory bulb, as well as the mature basilar pons. Using 400 different combinations of primers, we screened more than 11,000 labeled DNA fragments and identified 201 that exhibited higher expression in the basilar pons than in the control tissues. From these, 138 distinct gene fragments were cloned. The differential expression of a large subset of these fragments was confirmed using RNase protection assays. In situ hybridization analysis revealed that the expression of many of these genes is limited to the basilar pons and only a few other brain regions, suggesting that they may play specific roles in pontine development.
Collapse
Affiliation(s)
- M Gesemann
- Molecular Neurobiology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, San Diego, California 92037, USA
| | | | | | | | | |
Collapse
|
18
|
Leighton PA, Mitchell KJ, Goodrich LV, Lu X, Pinson K, Scherz P, Skarnes WC, Tessier-Lavigne M. Defining brain wiring patterns and mechanisms through gene trapping in mice. Nature 2001; 410:174-9. [PMID: 11242070 DOI: 10.1038/35065539] [Citation(s) in RCA: 326] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The search to understand the mechanisms regulating brain wiring has relied on biochemical purification approaches in vertebrates and genetic approaches in invertebrates to identify molecular cues and receptors for axon guidance. Here we describe a phenotype-based gene-trap screen in mice designed for the large-scale identification of genes controlling the formation of the trillions of connections in the mammalian brain. The method incorporates an axonal marker, which helps to identify cell-autonomous mechanisms in axon guidance, and has generated a resource of mouse lines with striking patterns of axonal labelling, which facilitates analysis of the normal wiring diagram of the brain. Studies of two of these mouse lines have identified an in vivo guidance function for a vertebrate transmembrane semaphorin, Sema6A, and have helped re-evaluate that of the Eph receptor EphA4.
Collapse
Affiliation(s)
- P A Leighton
- Howard Hughes Medical Institute and Department of Anatomy, University of California, San Francisco, California 94143-0452, USA
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Klostermann A, Lutz B, Gertler F, Behl C. The orthologous human and murine semaphorin 6A-1 proteins (SEMA6A-1/Sema6A-1) bind to the enabled/vasodilator-stimulated phosphoprotein-like protein (EVL) via a novel carboxyl-terminal zyxin-like domain. J Biol Chem 2000; 275:39647-53. [PMID: 10993894 DOI: 10.1074/jbc.m006316200] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal development and apoptosis critically depend on the transformation of extracellular signals to intracellular actions resulting in cytoskeletal rearrangements. Ena/VASP (enabled/vasodilator-stimulated phosphoprotein) proteins play an important role in actin and filament dynamics, whereas members of the semaphorin protein family are guidance signals in embryo- and organogenesis. Here, we report the identification of two novel transmembranous human and murine semaphorins, (HSA)SEMA6A-1 and (MMU)Sema6A-1. These semaphorin 6 variants directly link the Ena/VASP and the semaphorin protein family, since SEMA6A-1/Sema6A-1 is capable of a selective binding to the protein EVL (Ena/VASP-like protein). EVL is the third member of the Ena/VASP family of proteins that was identified sharing the same structural features as Mena (mammalian enabled) and VASP, although its functionality seems to be different from that of the other members. Here we demonstrate that SEMA6A-1/Sema6A-1 is colocalized with EVL via its zyxin-like carboxyl-terminal domain that contains a modified binding motif, which further stresses the existence of functional differences between EVL and Mena/VASP. In addition these findings suggest a completely new role for transmembranous semaphorins such as SEMA6A-1/Sema6A-1 in retrograde signaling.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Apoptosis
- Blotting, Northern
- Blotting, Western
- Cell Adhesion Molecules/chemistry
- Cell Adhesion Molecules/metabolism
- Cell Adhesion Molecules, Neuronal/chemistry
- Cell Adhesion Molecules, Neuronal/metabolism
- Cell Line
- Cells, Cultured
- Chromosome Mapping
- Chromosomes, Human, Pair 5
- Cloning, Molecular
- Cytoskeletal Proteins
- Electrophoresis, Polyacrylamide Gel
- Glycoproteins
- Humans
- Immunohistochemistry
- In Situ Hybridization
- Metalloproteins/chemistry
- Mice
- Microfilament Proteins
- Molecular Sequence Data
- Phosphoproteins/chemistry
- Phosphoproteins/metabolism
- Precipitin Tests
- Protein Binding
- Protein Isoforms
- Protein Structure, Tertiary
- RNA, Messenger/metabolism
- Rabbits
- Semaphorins
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Signal Transduction
- Tissue Distribution
- Transfection
- Zyxin
Collapse
Affiliation(s)
- A Klostermann
- MPI of Psychiatry, Independent Research Group Neurodegeneration, Kraepelinstrasse 2, 80804 Munich, Germany
| | | | | | | |
Collapse
|
20
|
Abstract
Semaphorin 6A (Sema6A) (previously named Semaphorin VIa) is the originally described member of the vertebrate semaphorin class 6, a group of transmembrane semaphorins homologous to the insect semaphorin class 1. Although Sema-1a (previously named semaphorin I) has been implicated in axon guidance in insects, the function of Sema6A is currently unknown. We have expressed the extracellular domain of Sema6A in mammalian cells as either a monomeric or a dimeric fusion protein and tested for potential axon guidance effects on two populations of embryonic neurons in growth cone collapse and collagen matrix chemorepulsion assays. Sema6A was observed to induce growth cone collapse of sympathetic neurons with an EC50 of approximately 200 pM, although a 10-fold higher (EC50 of approximately 2 nM) concentration was necessary to induce growth cone collapse of dorsal root ganglion neurons. The activity of Sema6A is likely to depend on protein dimerization or oligomerization. Although Sema6A mRNA is expressed in complex patterns during embryonic development, it is strikingly absent from sympathetic ganglia. Sema6A is, however, expressed in areas avoided by sympathetic axons and in areas innervated by sympathetics, but before their arrival. Our results demonstrate that transmembrane semaphorins, like the secreted ones, can act as repulsive axon guidance cues. Our findings are consistent with a role for Sema6A in channeling sympathetic axons into the sympathetic chains and controlling the temporal sequence of sympathetic target innervation.
Collapse
|
21
|
Steup A, Lohrum M, Hamscho N, Savaskan NE, Ninnemann O, Nitsch R, Fujisawa H, Püschel AW, Skutella T. Sema3C and netrin-1 differentially affect axon growth in the hippocampal formation. Mol Cell Neurosci 2000; 15:141-55. [PMID: 10673323 DOI: 10.1006/mcne.1999.0818] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interaction between outgrowing neurons and their targets is a central element in the development of the afferent and efferent connections of the hippocampal system. This requires that axonal growth cones recognize specific guidance cues in the appropriate target area. At present, little is known about the mechanisms that determine the lamina-specific termination of hippocampal afferents. In order to understand the role of different guidance factors, we analyzed the effects of Sema3C and Netrin-1 on explants from the entorhinal cortex, dentate gyrus, cornu ammonis regions CA1 and CA3 and medial septum in a collagen coculture assay. Our observations suggest that both semaphorins and netrin play important roles in the neuron-target interactions in the hippocampal system. Sema3C is involved in the control of the ingrowth of the septohippocampal projection. We also show that netrin-1 is involved in attracting commissural neurons from dentate gyrus/hilus and CA3 to their target area in the contralateral hippocampus.
Collapse
Affiliation(s)
- A Steup
- Institute of Anatomy, Department of Cell- and Neurobiology, Humboldt University Hospital, Charité, Berlin, 10098, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Bork P, Doerks T, Springer TA, Snel B. Domains in plexins: links to integrins and transcription factors. Trends Biochem Sci 1999; 24:261-3. [PMID: 10390613 DOI: 10.1016/s0968-0004(99)01416-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- P Bork
- EMBL, Meyerhofstr. 1, 69012 Heidelberg, Germany; and Max-Delbrück-Centrum, Robert-Roessle-Strasse 10, 13125 Berlin, Germany
| | | | | | | |
Collapse
|
23
|
Collapsin-1/semaphorin-III/D is regulated developmentally in Purkinje cells and collapses pontocerebellar mossy fiber neuronal growth cones. J Neurosci 1999. [PMID: 10341245 DOI: 10.1523/jneurosci.19-11-04437.1999] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Most axons in the CNS innervate specific subregions or layers of their target regions and form contacts with specific types of target neurons, but the molecular basis of this process is not well understood. To determine whether collapsin-1/semaphorin-III/D, a molecule known to repel specific axons, might guide afferent axons within their cerebellar targets, we characterized its expression by in situ hybridization and observed its effects on mossy and climbing fiber extension and growth cone size in vitro. In newborn mice sema-D is expressed by cerebellar Purkinje cells in parasagittal bands located medially and in some cells of the cerebellar nuclei. Later, sema-D expression in Purkinje cells broadens such that banded expression is no longer prominent, and expression is detected in progressively more lateral regions. By postnatal day 16, expression is observed throughout the cerebellar mediolateral axis. Collapsin-1 protein, the chick ortholog of sema-D, did not inhibit the extension of neurites from explants of inferior olivary nuclei, the source of climbing fibers that innervate Purkinje cells. In contrast, when it was applied to axons extending from basilar pontine explants, a source of mossy fiber afferents of granule cells, collapsin-1 caused most pontine growth cones to collapse, as evidenced by a reduction in growth cone size of up to 59%. Moreover, 63% of pontine growth cones arrested their extension or retracted. Its effects on mossy fiber extension and its distribution suggest that sema-D prevents mossy fibers from innervating inappropriate cerebellar target regions and cell types.
Collapse
|
24
|
Braisted JE, Tuttle R, O'leary DD. Thalamocortical axons are influenced by chemorepellent and chemoattractant activities localized to decision points along their path. Dev Biol 1999; 208:430-40. [PMID: 10191056 DOI: 10.1006/dbio.1999.9216] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thalamocortical axons (TCAs), which originate in dorsal thalamus, project ventrally in diencephalon and then dorsolaterally in ventral telencephalon to their target, the neocortex. To elucidate potentially key decision points in TCA pathfinding and hence the possible localization of guidance cues, we used DiI-tracing to describe the initial trajectory of TCAs in mice. DiI-labeled TCAs extend ventrally on the lateral surface of ventral thalamus. Rather than continuing this trajectory onto the lateral surface of the hypothalamus, TCAs make a sharp lateral turn into ventral telencephalon. This behavior suggests that the hypothalamus is repulsive and the ventral telencephalon attractive for TCAs. In support of this hypothesis, we find that axon outgrowth from explants of dorsal thalamus is biased away from hypothalamus and toward ventral telencephalon when cocultured at a distance in collagen gels. The in vivo DiI analysis also reveals a broad cluster of retrogradely labeled neurons in the medial part of ventral telencephalon positioned within or adjacent to the thalamocortical pathway prior to or at the time TCAs are extending through it. The axons of these neurons extend into or through dorsal thalamus and appear to be coincident with the oppositely extending TCAs. These findings suggest that multiple cues guide TCAs along their pathway from dorsal thalamus to neocortex: TCAs may fasciculate on the axons of ventral telencephalic neurons as they extend through ventral thalamus and the medial part of ventral telencephalon, and chemorepellent and chemoattractant activities expressed by hypothalamus and ventral telencephalon, respectively, may cooperate to promote the turning of TCAs away from hypothalamus and into ventral telencephalon.
Collapse
Affiliation(s)
- J E Braisted
- Molecular Neurobiology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, California, 92037, USA
| | | | | |
Collapse
|
25
|
Ulupinar E, Datwani A, Behar O, Fujisawa H, Erzurumlu R. Role of semaphorin III in the developing rodent trigeminal system. Mol Cell Neurosci 1999; 13:281-92. [PMID: 10328887 PMCID: PMC3678352 DOI: 10.1006/mcne.1999.0747] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Semaphorins are a large family of secreted and transmembrane glycoproteins. Sema III, a member of the Class III semaphorins is a potent chemorepulsive signal for subsets of sensory axons and steers them away from tissue regions with high levels of expression. Previous studies in mutant mice lacking sema III gene showed various neural and nonneural abnormalities. In this study, we focused on the developing trigeminal pathway of sema III knockout mice. We show that the peripheral and central trigeminal projections are impaired during initial pathway formation when they develop into distinct nerves or tracts. These axons defasciculate and compromise the normal bundling of nerves and restricted alignment of the central tract. In contrast to trigeminal projections, thalamocortical projections to the barrel cortex appear normal. Furthermore, sema III receptor, neuropilin, is expressed during a short period of development when the tract is laid down, but not in the developing thalamocortical pathway. Peripherally, trigeminal axons express neuropilin for longer duration than their central counterparts. In spite of projection errors, whisker follicle innervation appears normal and whisker-related patterns form in the trigeminal nuclei and upstream thalamic and cortical centers. Our observations suggest that sema III plays a limited role during restriction of developing trigeminal axons to proper pathways and tracts. Other molecular and cellular mechanisms must act in concert with semaphorins in ensuring target recognition, topographic order of projections, and patterning of neural connections.
Collapse
Affiliation(s)
- E Ulupinar
- Department of Cell Biology and Anatomy and Neuroscience Center, LSU Medical Center, New Orleans, Louisiana, USA
| | | | | | | | | |
Collapse
|
26
|
Encinas JA, Kikuchi K, Chedotal A, de Castro F, Goodman CS, Kimura T. Cloning, expression, and genetic mapping of Sema W, a member of the semaphorin family. Proc Natl Acad Sci U S A 1999; 96:2491-6. [PMID: 10051670 PMCID: PMC26812 DOI: 10.1073/pnas.96.5.2491] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The semaphorins comprise a large family of membrane-bound and secreted proteins, some of which have been shown to function in axon guidance. We have cloned a transmembrane semaphorin, Sema W, that belongs to the class IV subgroup of the semaphorin family. The mouse and rat forms of Sema W show 97% amino acid sequence identity with each other, and each shows about 91% identity with the human form. The gene for Sema W is divided into 15 exons, up to 4 of which are absent in the human cDNAs that we sequenced. Unlike many other semaphorins, Sema W is expressed at low levels in the developing embryo but was found to be expressed at high levels in the adult central nervous system and lung. Functional studies with purified membrane fractions from COS7 cells transfected with a Sema W expression plasmid showed that Sema W has growth-cone collapse activity against retinal ganglion-cell axons, indicating that vertebrate transmembrane semaphorins, like secreted semaphorins, can collapse growth cones. Genetic mapping of human SEMAW with human/hamster radiation hybrids localized the gene to chromosome 2p13. Genetic mapping of mouse Semaw with mouse/hamster radiation hybrids localized the gene to chromosome 6, and physical mapping placed the gene on bacteria artificial chromosomes carrying microsatellite markers D6Mit70 and D6Mit189. This localization places Semaw within the locus for motor neuron degeneration 2, making it an attractive candidate gene for this disease.
Collapse
Affiliation(s)
- J A Encinas
- Sumitomo Pharmaceuticals Research Center, 3-1-98 Kasugade-Naka, Konohana, Osaka 554-0022, Japan
| | | | | | | | | | | |
Collapse
|
27
|
Giger RJ, Pasterkamp RJ, Holtmaat AJ, Verhaagen J. Semaphorin III: role in neuronal development and structural plasticity. PROGRESS IN BRAIN RESEARCH 1999; 117:133-49. [PMID: 9932406 DOI: 10.1016/s0079-6123(08)64013-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- R J Giger
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185, USA.
| | | | | | | |
Collapse
|
28
|
Affiliation(s)
- A L Kolodkin
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185, USA.
| |
Collapse
|
29
|
Kikuchi K, Chédotal A, Hanafusa H, Ujimasa Y, de Castro F, Goodman CS, Kimura T. Cloning and characterization of a novel class VI semaphorin, semaphorin Y. Mol Cell Neurosci 1999; 13:9-23. [PMID: 10049528 DOI: 10.1006/mcne.1998.0732] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Semaphorins comprise a large family of proteins implicated in axonal guidance. We cloned a novel transmembrane semaphorin, semaphorin Y (Sema Y), which has a class VI sema domain. Sema Y shows growth cone collapsing activity on DRG neurons in vitro, and the target regions of the DRG neurons express sema Y mRNA during development. Sema Y may be a stop signal for these neurons in their target areas. Interestingly, sema Y mRNA was also detected in other neurons and their targets. Two isoforms of Sema Y derived from alternative splicing were identified and their expression was found to be regulated in a tissue- and age-dependent manner. Distribution of sema Y mRNA suggests that Sema Y might also be important during maintenance of axonal connections and/or differentiation and migration of cells. Sequence comparison among class VI semaphorins revealed two short conserved sequence stretches in their cytoplasmic domains, suggesting interaction of these semaphorins with a common intracellular component(s).
Collapse
Affiliation(s)
- K Kikuchi
- Sumitomo Pharmaceuticals Research Center, 3-1-98, Kasugade-Naka, Konohana, Osaka, 554-0022, Japan
| | | | | | | | | | | | | |
Collapse
|
30
|
Halloran MC, Severance SM, Yee CS, Gemza DL, Raper JA, Kuwada JY. Analysis of a Zebrafish semaphorin reveals potential functions in vivo. Dev Dyn 1999; 214:13-25. [PMID: 9915572 DOI: 10.1002/(sici)1097-0177(199901)214:1<13::aid-dvdy2>3.0.co;2-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The semaphorin/collapsin gene family is a large and diverse family encoding both secreted and transmembrane proteins, some of which are thought to act as repulsive axon guidance molecules. However, the function of most semaphorins is still unknown. We have cloned and characterized several semaphorins in the zebrafish in order to assess their in vivo function. Zebrafish semaZ2 is expressed in a dynamic and restricted pattern during the period of axon outgrowth that indicates potential roles in the guidance of several axon pathways. Analysis of mutant zebrafish with reduced semaZ2 expression reveals axon pathfinding errors that implicate SemaZ2 in normal guidance.
Collapse
Affiliation(s)
- M C Halloran
- Department of Biology, University of Michigan, Ann Arbor 48109-1048, USA
| | | | | | | | | | | |
Collapse
|
31
|
Affiliation(s)
- H H Yu
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | | |
Collapse
|
32
|
Bagnard D, Lohrum M, Uziel D, Püschel AW, Bolz J. Semaphorins act as attractive and repulsive guidance signals during the development of cortical projections. Development 1998; 125:5043-53. [PMID: 9811588 DOI: 10.1242/dev.125.24.5043] [Citation(s) in RCA: 222] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Members of the semaphorin family have been implicated in mediating axonal guidance in the nervous system by their ability to collapse growth cones and to function as chemorepellents. The present findings show that recombinant Semaphorin D has similar effects on cortical axons and, in addition, inhibits axonal branching. In contrast, semaphorin E acts as an attractive guidance signal for cortical axons. Attractive effects were only observed when growth cones encountered increasing concentrations or a patterned distribution of Semaphorin E, but not when they are exposed to uniform concentrations of this molecule. Specific binding sites for Semaphorin D and Semaphorin E were present on cortical fibers both in vitro and in vivo at the time when corticofugal projections are established. In situ hybridization analysis revealed that the population of cortical neurons used in our experiments express neuropilin-1 and neuropilin-2, which are essential components of receptors for the class III semaphorins. Moreover, semD mRNA was detected in the ventricular zone of the neocortex whereas semE mRNA was restricted to the subventricular zone. Taken together, these results indicate that semaphorins are bifunctional molecules whose effects depend on their spatial distribution. The coordinated expression of different semaphorins, together with their specific activities on cortical axons, suggests that multiple guidance signals contribute to the formation of precise corticofugal pathways.
Collapse
Affiliation(s)
- D Bagnard
- INSERM Unité 371 'Cerveau et Vision', 69500 Bron, France
| | | | | | | | | |
Collapse
|
33
|
Chédotal A, Del Rio JA, Ruiz M, He Z, Borrell V, de Castro F, Ezan F, Goodman CS, Tessier-Lavigne M, Sotelo C, Soriano E. Semaphorins III and IV repel hippocampal axons via two distinct receptors. Development 1998; 125:4313-23. [PMID: 9753685 DOI: 10.1242/dev.125.21.4313] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The semaphorins are the largest family of repulsive axon guidance molecules. Secreted semaphorins bind neuropilin receptors and repel sensory, sympathetic and motor axons. Here we show that CA1, CA3 and dentate gyrus axons from E15-E17 mouse embryo explants are selectively repelled by entorhinal cortex and neocortex. The secreted semaphorins Sema III and Sema IV and their receptors Neuropilin-1 and −2 are expressed in the hippocampal formation during appropriate stages. Sema III and Sema IV strongly repel CA1, CA3 and dentate gyrus axons; entorhinal axons are only repelled by Sema III. An antibody against Neuropilin-1 blocks the repulsive action of Sema III and the entorhinal cortex, but has no effect on Sema IV-induced repulsion. Thus, chemorepulsion plays a role in axon guidance in the hippocampus, secreted semaphorins are likely to be responsible for this action, and the same axons can be repelled by two distinct semaphorins via two different receptors.
Collapse
Affiliation(s)
- A Chédotal
- INSERM U106, Hôpital de la Salpêtrière, France.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Abstract
We examined axon-target interactions in cocultures of embryonic rat trigeminal, dorsal root, nodose, superior cervical ganglia or retina with a variety of native or foreign peripheral targets such as the whisker pad, forepaw, and heart explants. Axon growth into these peripheral target tissues was analyzed by the use of lipophilic tracer DiI. Embryonic day 15 dorsal root and trigeminal axons grew into isochronic normal and foreign cutaneous targets. Both axon populations avoided the same age heart tissue, but grew profusely into younger (embryonic day 13) or older (postnatal) heart explants. In contrast, embryonic day 15 superior cervical or nodose ganglion axons grew heavily into the same age heart and forepaw explants and to a lesser extent into the whisker pad explants. Embryonic day 15 retinal axons grew into all three peripheral targets used in this study. Primary sensory and sympathetic axons, but not retinal axons, formed target-specific patterns in the whisker pad and forepaw explants. DiI-labeling and immunostaining of primary sensory neurons in coculture revealed that these neurons retain their bipolar characteristics, and express class-specific markers such as parvalbumin, calcitonin gene-related peptide and TrkA receptors. In the whisker pad explants, axons positive for all three markers were seen to form patterns around the follicles. Our results indicate that developing peripheral targets can attract and support axon growth from a variety of sources. Whereas neurotrophins play a major role in attracting and supporting survival of subpopulations of sensory neurons, other substrate-bound or locally released molecules must regulate sensory neurite growth into specific peripheral and central targets.
Collapse
Affiliation(s)
- E Ulupinar
- Department of Cell Biology and Anatomy and Neuroscience Center, Louisiana State University Medical Center, New Orleans 70112, USA
| | | |
Collapse
|
35
|
Abstract
Chemorepulsive signals that repel or paralyze neuronal growth cones have been found to play important roles in axon guidance in a stereotyped manner. Recent progress in the identification of neuropilins as the receptors for class III secreted collapsin/semaphorin subfamily members, which are neuronal repellents, and in the analysis of mutant mice lacking neuropilin function has confirmed the importance of these chemorepellents in axon guidance. In addition, characterization of the neuropilin protein has yielded new insights into the functions of this molecule in vascular formation and in axon guidance.
Collapse
Affiliation(s)
- H Fujisawa
- Group of Developmental Neurobiology, Nagoya University Graduate School of Science, Japan.
| | | |
Collapse
|
36
|
Xu X, Ng S, Wu ZL, Nguyen D, Homburger S, Seidel-Dugan C, Ebens A, Luo Y. Human semaphorin K1 is glycosylphosphatidylinositol-linked and defines a new subfamily of viral-related semaphorins. J Biol Chem 1998; 273:22428-34. [PMID: 9712866 DOI: 10.1074/jbc.273.35.22428] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The semaphorin family contains a large number of secreted and transmembrane proteins, some of which are known to act as repulsive axon guidance cues during development or to be involved in immune function. We report here on the identification of semaphorin K1 (sema K1), the first semaphorin known to be associated with cell surfaces via a glycosylphosphatidylinositol linkage. Sema K1 is highly homologous to a viral semaphorin and can interact with specific immune cells, suggesting that like its viral counterpart, sema K1 could play an important role in regulating immune function. Sema K1 does not bind to neuropilin-1 or neuropilin-2, the two receptors implicated in mediating the repulsive action of several secreted semaphorins, and thus it likely acts through a novel receptor. In contrast to most previously described semaphorins, sema K1 is only weakly expressed during development but is present at high levels in postnatal and adult tissues, particularly brain and spinal cord.
Collapse
Affiliation(s)
- X Xu
- Exelixis Pharmaceuticals, Inc., South San Francisco, California 94080, USA
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Lange C, Liehr T, Goen M, Gebhart E, Fleckenstein B, Ensser A. New eukaryotic semaphorins with close homology to semaphorins of DNA viruses. Genomics 1998; 51:340-50. [PMID: 9721204 DOI: 10.1006/geno.1998.5256] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Semaphorins were initially described as a family of repulsive guidance molecules in embryonal development. Their basic structure consists of an N-terminal signal sequence, the defining semaphorin domain ofapproximately 500 amino acids, an Ig-like domain,and a variable carboxy-terminus. We recently described a viral semaphorin homologue encoded by the alcelaphine herpesvirus type 1. Less conserved, truncated homologues were also identified in poxviruses. Here we describe new human and murine semaphorin homologues. The respective genes were cloned and sequenced, and they were termed H-Sema-L and M-Sema-L (HGMW-approved symbols SEMAL and Semal, respectively). A multiply spliced mRNA of 3.2 kb is expressed in human placenta, spleen, thymus, and gonadal tissue. H-Sema-L maps to chromosome 15q22.3-q23 and M-Sema-L to the homologous locus 9A3.3-B in the mouse genome. The expression patterns and the presence of related genes in large DNA viruses suggest that this new semaphorin has a relevant function in the immune system.
Collapse
Affiliation(s)
- C Lange
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schlossgarten 4, Erlangen, 91054, Germany
| | | | | | | | | | | |
Collapse
|
38
|
Catalano SM, Messersmith EK, Goodman CS, Shatz CJ, Chédotal A. Many major CNS axon projections develop normally in the absence of semaphorin III. Mol Cell Neurosci 1998; 11:173-82. [PMID: 9675049 DOI: 10.1006/mcne.1998.0687] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The semaphorins constitute a large gene family of transmembrane and secreted molecules, many of which are expressed in the nervous system. Genetic studies in Drosophila have revealed a role for semaphorins in axon guidance and synapse formation, and several in vitro studies in mice have demonstrated a dramatic chemorepellent effect of semaphorin III (Sema III) on the axons of several populations of neurons. To investigate the function of Sema III during in vivo axon guidance in the mammalian CNS, we studied the development of axonal projections in mutant mice lacking Sema III. Projections were studied for which either the in vitro evidence suggests a role for Sema III in axon guidance (e.g., cerebellar mossy fibers, thalamocortical axons, or cranial motor neurons) or the in vivo expression suggests a role for Sema III in axon guidance (e.g., cerebellar Purkinje cells, neocortex). We find that many major axonal projections, including climbing fiber, mossy fiber, thalamocortical, and basal forebrain projections and cranial nerves, develop normally in the absence of Sema III. Despite its in vitro function and in vivo expression, it appears as if Sema III is not absolutely required for the formation of many major CNS tracts. Such data are consistent with recent models suggesting that axon guidance is controlled by a balance of forces resulting from multiple guidance cues. Our data lead us to suggest that if Sema III functions in part to guide the formation of major axonal projections, then it does so in combination with both other semaphorins and other families of guidance molecules.
Collapse
Affiliation(s)
- S M Catalano
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, 94720-3200, USA
| | | | | | | | | |
Collapse
|
39
|
Comeau MR, Johnson R, DuBose RF, Petersen M, Gearing P, VandenBos T, Park L, Farrah T, Buller RM, Cohen JI, Strockbine LD, Rauch C, Spriggs MK. A poxvirus-encoded semaphorin induces cytokine production from monocytes and binds to a novel cellular semaphorin receptor, VESPR. Immunity 1998; 8:473-82. [PMID: 9586637 DOI: 10.1016/s1074-7613(00)80552-x] [Citation(s) in RCA: 207] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The vaccinia virus A39R protein is a member of the semaphorin family. A39R.Fc protein was used to affinity purify an A39R receptor from a human B cell line. Tandem mass spectrometry of receptor peptides yielded partial amino acid sequences that allowed the identification of corresponding cDNA clones. Sequence analysis of this receptor indicated that it is a novel member of the plexin family and identified a semaphorin-like domain within this family, thus suggesting an evolutionary relationship between receptor and ligand. A39R up-regulated ICAM-1 on, and induced cytokine production from, human monocytes. These data, then, describe a receptor for an immunologically active semaphorin and suggest that it may serve as a prototype for other plexin-semaphorin binding pairs.
Collapse
Affiliation(s)
- M R Comeau
- Department of Molecular Biology, Immunex Corporation, Seattle, Washington 98101, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Klostermann A, Lohrum M, Adams RH, Püschel AW. The chemorepulsive activity of the axonal guidance signal semaphorin D requires dimerization. J Biol Chem 1998; 273:7326-31. [PMID: 9516427 DOI: 10.1074/jbc.273.13.7326] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The axonal guidance signal semaphorin D is a member of a large family of proteins characterized by the presence of a highly conserved semaphorin domain of about 500 amino acids. The vertebrate semaphorins can be divided into four different classes that contain both secreted and membrane-bound proteins. Here we show that class III (SemD) and class IV semaphorins (SemB) form homodimers linked by intermolecular disulfide bridges. In addition to the 95-kDa form of SemD (SemD(95k)), proteolytic processing of SemD creates a 65-kDa isoform (SemD(65k)) that lacks the 33-kDa carboxyl-terminal domain. Although SemD(95k) formed dimers, the removal of the carboxyl-terminal domain resulted in the dissociation of SemD homodimers to monomeric SemD(65k). Mutation of cysteine 723, one of four conserved cysteine residues in the 33-kDa fragment, revealed its requirement both for the dimerization of SemD and its chemorepulsive activity. We suggest that dimerization is a general feature of sema- phorins which depends on class-specific sequences and is important for their function.
Collapse
Affiliation(s)
- A Klostermann
- Molekulare Neurogenetik, Abteilung Neurochemie, Max-Planck-Institut für Hirnforschung, Deutschordenstrasse 46, D-60528 Frankfurt/Main, Germany
| | | | | | | |
Collapse
|
41
|
Yu HH, Araj HH, Ralls SA, Kolodkin AL. The transmembrane Semaphorin Sema I is required in Drosophila for embryonic motor and CNS axon guidance. Neuron 1998; 20:207-20. [PMID: 9491983 DOI: 10.1016/s0896-6273(00)80450-x] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The semaphorins comprise a large family of conserved glycoproteins, several members of which have been shown to function in repulsive neuronal growth cone guidance. We show here that Drosophila Semaphorin I (Sema I), a transmembrane semaphorin expressed on embryonic motor and CNS axons, is required for correct guidance of motor axons and for the formation of CNS pathways. In mutant embryos lacking Sema I, motor axons stall and fail to defasciculate at specific choice points where normally they would project to their muscle targets. In addition, a specific CNS fascicle fails to form correctly in these embryos. Rescue and ectopic expression experiments show that Sema I is required in neurons to mediate axon guidance decisions. These studies further suggest that like secreted semaphorins, transmembrane semaphorins can function as repulsive guidance cues for specific axon guidance events during neurodevelopment.
Collapse
Affiliation(s)
- H H Yu
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | | | | | | |
Collapse
|
42
|
Eckhardt F, Behar O, Calautti E, Yonezawa K, Nishimoto I, Fishman MC. A novel transmembrane semaphorin can bind c-src. Mol Cell Neurosci 1997; 9:409-19. [PMID: 9361278 DOI: 10.1006/mcne.1997.0644] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The semaphorins/collapsins constitute a family of genes unified by the presence of a "semaphorin domain" which has been conserved through metazoan evolution. The semaphorin family comprises both secreted and transmembrane molecules and is thought to be made up of ligands for as yet unidentified receptors. The functions are not known, with the exception of those of sema III (also referred as sem D and collapsin 1), D-sema I, and D-sema II, which have been shown to be involved in axonal pathfinding. Here report the identification of a mouse semaphorin cDNA, termed Sema VIb. Although Sema VIb contains the extracellular semaphorin domain, it lacks the immunoglobulin domain or thrombospondin repeats which are present in other described vertebrate (but not invertebrate) transmembrane semaphorins. During development Sema VIb mRNA is expressed in subregions of the nervous system and is particularly prominent in muscle. In adulthood, Sema VIb mRNA is expressed ubiquitously. The cytoplasmic domain of Sema VIb contains several proline-rich potential SH3 domain binding sites. Using an in vitro binding assay, we show that Sema VIb binds specifically the SH3 domain of the protooncogene c-src. In transfected COS cells Sema VIb coimmunoprecipitates with c-src. These results, along with our evidence that Sema VIb can form dimers, suggests that the semaphorin family not only serves as ligands but may include members, especially those which are transmembrane, which serve as receptors, triggering intracellular signaling via an src-related cascade.
Collapse
Affiliation(s)
- F Eckhardt
- Cardiovascular Research Center, Massachusetts General Hospital (East), Charlestown 02129, USA
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
The importance of vision in the behavior of animals, from invertebrates to primates, has led to a good deal of interest in how projection neurons in the retina make specific connections with targets in the brain. Recent research has focused on the cellular interactions occurring between retinal ganglion cell (RGC) axons and specific glial and neuronal populations in the embryonic brain during formation of the mouse optic chiasm. These interactions appear to be involved both in determining the position of the optic chiasm on the ventral diencephalon (presumptive hypothalamus) and in ipsilateral and contralateral RGC axon pathfinding, development events fundamental to binocular vision in the adult animal.
Collapse
Affiliation(s)
- C A Mason
- Department of Pathology, Center for Neurobiology and Behavior, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
| | | |
Collapse
|
44
|
Chen H, Chédotal A, He Z, Goodman CS, Tessier-Lavigne M. Neuropilin-2, a novel member of the neuropilin family, is a high affinity receptor for the semaphorins Sema E and Sema IV but not Sema III. Neuron 1997; 19:547-59. [PMID: 9331348 DOI: 10.1016/s0896-6273(00)80371-2] [Citation(s) in RCA: 504] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Semaphorins are a large family of secreted and transmembrane proteins, several of which are implicated in repulsive axon guidance. Neuropilin (neuropilin-1) was recently identified as a receptor for Collapsin-1/Semaphorin III/D (Sema III). We report the identification of a related protein, neuropilin-2, whose mRNA is expressed by developing neurons in a pattern largely, though not completely, nonoverlapping with that of neuropilin-1. Unlike neuropilin-1, which binds with high affinity to the three structurally related semaphorins Sema III, Sema E, and Sema IV, neuropilin-2 shows high affinity binding only to Sema E and Sema IV, not Sema III. These results identify neuropilins as a family of receptors (or components of receptors) for at least one semaphorin subfamily. They also suggest that the specificity of action of different members of this subfamily may be determined by the complement of neuropilins expressed by responsive cells.
Collapse
Affiliation(s)
- H Chen
- Howard Hughes Medical Institute, Department of Anatomy, University of California, San Francisco 94143-0452, USA
| | | | | | | | | |
Collapse
|
45
|
Abstract
The semaphorin family contains a large number of phylogenetically conserved proteins and includes several members that have been shown to function in repulsive axon guidance. Semaphorin III (Sema III) is a secreted protein that in vitro causes neuronal growth cone collapse and chemorepulsion of neurites, and in vivo is required for correct sensory afferent innervation and other aspects of development. The mechanism of Sema III function, however, is unknown. Here, we report that neuropilin, a type I transmembrane protein implicated in aspects of neurodevelopment, is a Sema III receptor. We also describe the identification of neuropilin-2, a related neuropilin family member, and show that neuropilin and neuropilin-2 are expressed in overlapping, yet distinct, populations of neurons in the rat embryonic nervous system.
Collapse
Affiliation(s)
- A L Kolodkin
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA
| | | | | | | | | | | |
Collapse
|