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Hutchings C, Nuriel Y, Lazar D, Kohl A, Muir E, Genin O, Cinnamon Y, Benyamini H, Nevo Y, Sela-Donenfeld D. Hindbrain boundaries as niches of neural progenitor and stem cells regulated by the extracellular matrix proteoglycan chondroitin sulphate. Development 2024; 151:dev201934. [PMID: 38251863 PMCID: PMC10911165 DOI: 10.1242/dev.201934] [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: 05/02/2023] [Accepted: 01/12/2024] [Indexed: 01/23/2024]
Abstract
The interplay between neural progenitors and stem cells (NPSCs), and their extracellular matrix (ECM) is a crucial regulatory mechanism that determines their behavior. Nonetheless, how the ECM dictates the state of NPSCs remains elusive. The hindbrain is valuable to examine this relationship, as cells in the ventricular surface of hindbrain boundaries (HBs), which arise between any two neighboring rhombomeres, express the NPSC marker Sox2, while being surrounded with the membrane-bound ECM molecule chondroitin sulphate proteoglycan (CSPG), in chick and mouse embryos. CSPG expression was used to isolate HB Sox2+ cells for RNA-sequencing, revealing their distinguished molecular properties as typical NPSCs, which express known and newly identified genes relating to stem cells, cancer, the matrisome and cell cycle. In contrast, the CSPG- non-HB cells, displayed clear neural-differentiation transcriptome. To address whether CSPG is significant for hindbrain development, its expression was manipulated in vivo and in vitro. CSPG manipulations shifted the stem versus differentiation state of HB cells, evident by their behavior and altered gene expression. These results provide further understanding of the uniqueness of hindbrain boundaries as repetitive pools of NPSCs in-between the rapidly growing rhombomeres, which rely on their microenvironment to maintain their undifferentiated state during development.
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Affiliation(s)
- Carmel Hutchings
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Yarden Nuriel
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Daniel Lazar
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Ayelet Kohl
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Elizabeth Muir
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1TN, UK
| | - Olga Genin
- Agricultural Research Organization, Volcani Center, Department of Poultry and Aquaculture Science, Rishon LeTsiyon 7505101, Israel
| | - Yuval Cinnamon
- Agricultural Research Organization, Volcani Center, Department of Poultry and Aquaculture Science, Rishon LeTsiyon 7505101, Israel
| | - Hadar Benyamini
- Info-CORE, Bioinformatics Unit of the I-CORE at the Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Yuval Nevo
- Info-CORE, Bioinformatics Unit of the I-CORE at the Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
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Basha S, Jin-Smith B, Sun C, Pi L. The SLIT/ROBO Pathway in Liver Fibrosis and Cancer. Biomolecules 2023; 13:biom13050785. [PMID: 37238655 DOI: 10.3390/biom13050785] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/24/2023] [Accepted: 04/28/2023] [Indexed: 05/28/2023] Open
Abstract
Liver fibrosis is a common outcome of most chronic liver insults/injuries that can develop into an irreversible process of cirrhosis and, eventually, liver cancer. In recent years, there has been significant progress in basic and clinical research on liver cancer, leading to the identification of various signaling pathways involved in tumorigenesis and disease progression. Slit glycoprotein (SLIT)1, SLIT2, and SLIT3 are secreted members of a protein family that accelerate positional interactions between cells and their environment during development. These proteins signal through Roundabout receptor (ROBO) receptors (ROBO1, ROBO2, ROBO3, and ROBO4) to achieve their cellular effects. The SLIT and ROBO signaling pathway acts as a neural targeting factor regulating axon guidance, neuronal migration, and axonal remnants in the nervous system. Recent findings suggest that various tumor cells differ in SLIT/ROBO signaling levels and show varying degrees of expression patterns during tumor angiogenesis, cell invasion, metastasis, and infiltration. Emerging roles of the SLIT and ROBO axon-guidance molecules have been discovered in liver fibrosis and cancer development. Herein, we examined the expression patterns of SLIT and ROBO proteins in normal adult livers and two types of liver cancers: hepatocellular carcinoma and cholangiocarcinoma. This review also summarizes the potential therapeutics of this pathway for anti-fibrosis and anti-cancer drug development.
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Affiliation(s)
- Sreenivasulu Basha
- Department of Pathology, Tulane University School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112, USA
| | - Brady Jin-Smith
- Department of Pathology, Tulane University School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112, USA
| | - Chunbao Sun
- Department of Pathology, Tulane University School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112, USA
| | - Liya Pi
- Department of Pathology, Tulane University School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112, USA
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Yang T, Huang H, Shao Q, Yee S, Majumder T, Liu G. miR-92 Suppresses Robo1 Translation to Modulate Slit Sensitivity in Commissural Axon Guidance. Cell Rep 2018; 24:2694-2708.e6. [PMID: 30184503 DOI: 10.1016/j.celrep.2018.08.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 07/17/2018] [Accepted: 08/07/2018] [Indexed: 01/09/2023] Open
Abstract
Temporospatial regulation of guidance signaling is essential for axon outgrowth and pathfinding in the developing nervous system. Regulation of Robo1 levels in commissural neurons modulates Slit sensitivity facilitating proper axon guidance. The mechanisms underlying this regulation in the vertebrate nervous system are not well understood. Here, we report that miR-92, a highly conserved microRNA (miRNA), regulates chicken Robo1 expression in commissural neurons by binding to the 3' untranslated region (3' UTR) of Robo1 mRNA. miR-92 and Robo1 are differentially expressed in the developing spinal cord. miR-92 interacts with the Robo1 3'UTR to cause translational repression, but not mRNA degradation. Disruption of the miR-92/Robo1 3' UTR interaction induces premature responsiveness to Slit2 repulsion of precrossing commissural axons (CAs) in vitro and causes CA projection defects in vivo. These results indicate that miR-92 represses Robo1 expression thereby regulating Slit sensitivity to control CA projection and midline crossing.
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Affiliation(s)
- Tao Yang
- Department of Biological Sciences, University of Toledo, M.S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Huai Huang
- Department of Biological Sciences, University of Toledo, M.S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Qiangqiang Shao
- Department of Biological Sciences, University of Toledo, M.S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Shirley Yee
- Department of Biological Sciences, University of Toledo, M.S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Tanushree Majumder
- Department of Biological Sciences, University of Toledo, M.S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA
| | - Guofa Liu
- Department of Biological Sciences, University of Toledo, M.S. 601, 2801 W. Bancroft St., Toledo, OH 43606, USA.
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Junge HJ, Yung AR, Goodrich LV, Chen Z. Netrin1/DCC signaling promotes neuronal migration in the dorsal spinal cord. Neural Dev 2016; 11:19. [PMID: 27784329 PMCID: PMC5081974 DOI: 10.1186/s13064-016-0074-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/17/2016] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Newborn neurons often migrate before undergoing final differentiation, extending neurites, and forming synaptic connections. Therefore, neuronal migration is crucial for establishing neural circuitry during development. In the developing spinal cord, neuroprogenitors first undergo radial migration within the ventricular zone. Differentiated neurons continue to migrate tangentially before reaching the final positions. The molecular pathways that regulate these migration processes remain largely unknown. Our previous study suggests that the DCC receptor is important for the migration of the dorsal spinal cord progenitors and interneurons. In this study, we determined the involvement of the Netrin1 ligand and the ROBO3 coreceptor in the migration. RESULTS By pulse labeling neuroprogenitors with electroporation, we examined their radial migration in Netrin1 (Ntn1), Dcc, and Robo3 knockout mice. We found that all three mutants exhibit delayed migration. Furthermore, using immunohistochemistry of the BARHL2 interneuron marker, we found that the mediolateral and dorsoventral migration of differentiated dorsal interneurons is also delayed. Together, our results suggest that Netrin1/DCC signaling induce neuronal migration in the dorsal spinal cord. CONCLUSIONS Netrin1, DCC, and ROBO3 have been extensively studied for their functions in regulating axon guidance in the spinal commissural interneurons. We reveal that during earlier development of dorsal interneurons including commissural neurons, these molecules play an important role in promoting cell migration.
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Affiliation(s)
- Harald J Junge
- Department of MCDB, University of Colorado, Boulder, CO, 80309, USA.
| | - Andrea R Yung
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Lisa V Goodrich
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Zhe Chen
- Department of MCDB, University of Colorado, Boulder, CO, 80309, USA.
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Philipp M, Niederkofler V, Debrunner M, Alther T, Kunz B, Stoeckli ET. RabGDI controls axonal midline crossing by regulating Robo1 surface expression. Neural Dev 2012; 7:36. [PMID: 23140504 PMCID: PMC3520763 DOI: 10.1186/1749-8104-7-36] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/12/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Axons navigate to their future synaptic targets with the help of choice points, intermediate targets that express axon guidance cues. Once they reach a choice point, axons need to switch their response from attraction to repulsion in order to move on with the next stage of their journey. The mechanisms underlying the change in axonal responsiveness are poorly understood. Commissural axons become sensitive to the repulsive activity of Slits when they cross the ventral midline of the CNS. Responsiveness to Slits depends on surface expression of Robo receptors. In Drosophila, Commissureless (Comm) plays a crucial regulatory role in midline crossing by keeping Robo levels low on precommissural axons. Interestingly, to date no vertebrate homolog of comm has been identified. Robo3/Rig1 has been shown to control Slit sensitivity before the midline, but without affecting Robo1 surface expression. RESULTS We had identified RabGDI, a gene linked to human mental retardation and an essential component of the vesicle fusion machinery, in a screen for differentially expressed floor-plate genes. Downregulation of RabGDI by in ovo RNAi caused commissural axons to stall in the floor plate, phenocopying the effect observed after downregulation of Robo1. Conversely, premature expression of RabGDI prevented commissural axons from entering the floor plate. Furthermore, RabGDI triggered Robo1 surface expression in cultured commissural neurons. Taken together, our results identify RabGDI as a component of the switching mechanism that is required for commissural axons to change their response from attraction to repulsion at the intermediate target. CONCLUSION RabGDI takes over the functional role of fly Comm by regulating the surface expression of Robo1 on commissural axons in vertebrates. This in turn allows commissural axons to switch from attraction to repulsion at the midline of the spinal cord.
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Affiliation(s)
- Melanie Philipp
- Institute for Biochemistry and Molecular Biology, University of Ulm, Ulm, Germany
| | | | - Marc Debrunner
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, Zurich, CH, 8057, Switzerland
| | - Tobias Alther
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, Zurich, CH, 8057, Switzerland
| | - Beat Kunz
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, Zurich, CH, 8057, Switzerland
| | - Esther T Stoeckli
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, Zurich, CH, 8057, Switzerland
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Mortazavi MM, Verma K, Deep A, Esfahani FB, Pritchard PR, Tubbs RS, Theodore N. Chemical priming for spinal cord injury: a review of the literature part II-potential therapeutics. Childs Nerv Syst 2011; 27:1307-16. [PMID: 21174102 DOI: 10.1007/s00381-010-1365-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 12/07/2010] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Spinal cord injury is a complex cascade of reactions secondary to the initial mechanical trauma that puts into action the innate properties of the injured cells, the circulatory, inflammatory, and chemical status around them, into a non-permissive and destructive environment for neuronal function and regeneration. Priming means putting a cell, in a state of "arousal" towards better function. Priming can be mechanical as trauma is known to enhance activity in cells. MATERIALS AND METHODS A comprehensive review of the literature was performed to better understand the possible chemical primers used for spinal cord injuries. CONCLUSIONS Taken together, many studies have shown various promising results using the substances outlined herein for treating SCI.
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Affiliation(s)
- Martin M Mortazavi
- Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AR, USA
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Mortazavi MM, Verma K, Deep A, Esfahani FB, Pritchard PR, Tubbs RS, Theodore N. Chemical priming for spinal cord injury: a review of the literature. Part I-factors involved. Childs Nerv Syst 2011; 27:1297-306. [PMID: 21170536 DOI: 10.1007/s00381-010-1364-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 12/07/2010] [Indexed: 12/29/2022]
Abstract
INTRODUCTION There are significant differences between the propensity of neural regeneration between the central and peripheral nervous systems. MATERIALS AND METHODS Following a review of the literature, we describe the role of growth factors, guiding factors, and neurite outgrowth inhibitors in the physiology and development of the nervous system as well as the pathophysiology of the spinal cord. We also detail their therapeutic role as well as those of other chemical substances that have recently been found to modify regrowth following cord injury. CONCLUSIONS Multiple factors appear to have promising futures for the possibility of improving spinal cord injury following injury.
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Affiliation(s)
- Martin M Mortazavi
- Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AR, USA
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Shi M, Liu Z, Lv Y, Zheng M, Du F, Zhao G, Huang Y, Chen J, Han H, Ding Y. Forced notch signaling inhibits commissural axon outgrowth in the developing chick central nerve system. PLoS One 2011; 6:e14570. [PMID: 21283742 PMCID: PMC3024975 DOI: 10.1371/journal.pone.0014570] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Accepted: 12/24/2010] [Indexed: 11/18/2022] Open
Abstract
Background A collection of in vitro evidence has demonstrated that Notch signaling plays a key role in the growth of neurites in differentiated neurons. However, the effects of Notch signaling on axon outgrowth in an in vivo condition remain largely unknown. Methodology/Principal Findings In this study, the neural tubes of HH10-11 chick embryos were in ovo electroporated with various Notch transgenes of activating or inhibiting Notch signaling, and then their effects on commissural axon outgrowth across the floor plate midline in the chick developing central nerve system were investigated. Our results showed that forced expression of Notch intracellular domain, constitutively active form of RBPJ, or full-length Hes1 in the rostral hindbrain, diencephalon and spinal cord at stage HH10-11 significantly inhibited commissural axon outgrowth. On the other hand, inhibition of Notch signaling by ectopically expressing a dominant-negative form of RBPJ promoted commissural axonal growth along the circumferential axis. Further results revealed that these Notch signaling-mediated axon outgrowth defects may be not due to the alteration of axon guidance since commissural axon marker TAG1 was present in the axons in floor plate midline, and also not result from the changes in cell fate determination of commissural neurons since the expression of postmitotic neuron marker Tuj1 and specific commissural markers TAG1 and Pax7 was unchanged. Conclusions/Significance We first used an in vivo system to provide evidence that forced Notch signaling negatively regulates commissural axon outgrowth.
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Affiliation(s)
- Ming Shi
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
- * E-mail: (MS); (YD)
| | - Zhirong Liu
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yonggang Lv
- Department of Vascular and Endocrine Surgery, First Affiliated Hospital, Fourth Military Medical University, Xi'an, China
| | - Minhua Zheng
- Department of Medical Genetics and Developmental Biology, Fourth Military Medical University, Xi'an, China
| | - Fang Du
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Gang Zhao
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Ying Huang
- Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, China
| | - Jiayin Chen
- Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, China
| | - Hua Han
- Department of Medical Genetics and Developmental Biology, Fourth Military Medical University, Xi'an, China
| | - Yuqiang Ding
- Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, China
- * E-mail: (MS); (YD)
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Miranda DM, Wigg K, Feng Y, Sandor P, Barr CL. Association study between Gilles de la Tourette Syndrome and two genes in the Robo-Slit pathway located in the chromosome 11q24 linked/associated region. Am J Med Genet B Neuropsychiatr Genet 2008; 147B:68-72. [PMID: 17671968 DOI: 10.1002/ajmg.b.30580] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Gilles de la Tourette Syndrome (GTS) is an inherited neuropsychiatric disorder characterized by the presence of motor and phonic tics. Previous genetic studies have identified linkage and association between GTS and the 11q24 chromosomal region. We selected for study, within this region, two possible susceptibility genes for GTS, the ROBO3 and ROBO4 genes. These two genes were selected because of the recent identification of SLITRK1 as a potential susceptibility gene for GTS based on a translocation breakpoint and the further finding of two mutations in the SLITRK1 gene in three patients with GTS. While thus far, the SLITRK1 gene appears to account for only a few cases of GTS, these findings, if confirmed, point to other genes in these pathways that may contribute to GTS. Based on this, we examined two genes in the Slit-Robo pathway involved in cell migration, axonal pathfinding, and/or neuronal differentiation because of their location in 11q24, a region previously identified as linked and associated with GTS. We selected six haplotype tagging single nucleotide polymorphisms (SNPs) for ROBO3 and four for ROBO4 and genotyped them in our sample of trios and sibpair families diagnosed with GTS. Based on 155 nuclear families with 255 affected children, we did not find evidence for association between GTS and either the ROBO3 or ROBO4 genes. Thus, these two genes are unlikely to be the susceptibility genes contributing to GTS on 11q24.
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Affiliation(s)
- D M Miranda
- Department of Pharmacology of Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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Zhu Y, Guthrie S, Murakami F. Ephrin A/EphA controls the rostral turning polarity of a lateral commissural tract in chick hindbrain. Development 2006; 133:3837-46. [PMID: 16968816 DOI: 10.1242/dev.02564] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Most post-crossing commissural axons turn into longitudinal paths to make synaptic connections with their targets. Mechanisms that control their rostrocaudal turning polarity are still poorly understood. We used the hindbrain as a model system to investigate the rostral turning of a laterally located commissural tract, identified as the caudal group of contralateral cerebellar-projecting second-order vestibular neurons (cC-VC). We found that the caudal hindbrain possessed a graded non-permissive/repulsive activity for growing cC-VC axons. This non-permissiveness/repulsion was in part mediated by glycosyl-phosphatidylinositol (GPI)-anchored ephrin A. We further demonstrated that ephrin A2 was distributed in a caudal-high/rostral-low gradient in the caudolateral hindbrain and cC-VC axons expressed EphA receptors. Finally,perturbing ephrin A/EphA signalling both in vitro and in vivo led to rostrocaudal pathfinding errors of post-crossing cC-VC axons. These results suggest that ephrin A/EphA interactions play a key role in regulating the polarity of post-crossing cC-VC axons as they turn into the longitudinal axis.
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Affiliation(s)
- Yan Zhu
- SORST, Japan Science and Technology, Japan.
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Challa AK, McWhorter ML, Wang C, Seeger MA, Beattie CE. Robo3 isoforms have distinct roles during zebrafish development. Mech Dev 2006; 122:1073-86. [PMID: 16129585 DOI: 10.1016/j.mod.2005.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Accepted: 06/17/2005] [Indexed: 11/16/2022]
Abstract
Roundabout (Robo) receptors and their secreted ligand Slits have been shown to function in a number of developmental events both inside and outside of the nervous system. We previously cloned zebrafish robo orthologs to gain a better understanding of Robo function in vertebrates. Further characterization of one of these orthologs, robo3, has unveiled the presence of two distinct isoforms, robo3 variant 1 (robo3var1) and robo3 variant 2 (robo3var2). These two isoforms differ only in their 5'-ends with robo3var1, but not robo3var2, containing a canonical signal sequence. Despite this difference, both forms accumulate on the cell surface. Both isoforms are contributed maternally and exhibit unique and dynamic gene expression patterns during development. Functional analysis of robo3 isoforms using an antisense gene knockdown strategy suggests that Robo3var1 functions in motor axon pathfinding, whereas Robo3var2 appears to function in dorsoventral cell fate specification. This study reveals a novel function for Robo receptors in specifying ventral cell fates during vertebrate development.
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Affiliation(s)
- Anil K Challa
- Center for Molecular Neurobiology, Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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