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Sempert K, Shohayeb B, Lanoue V, O'Brien EA, Flores C, Cooper HM. RGMa and Neogenin control dendritic spine morphogenesis via WAVE Regulatory Complex-mediated actin remodeling. Front Mol Neurosci 2023; 16:1253801. [PMID: 37928069 PMCID: PMC10620725 DOI: 10.3389/fnmol.2023.1253801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/06/2023] [Indexed: 11/07/2023] Open
Abstract
Structural plasticity, the ability of dendritic spines to change their volume in response to synaptic stimulation, is an essential determinant of synaptic strength and long-term potentiation (LTP), the proposed cellular substrate for learning and memory. Branched actin polymerization is a major force driving spine enlargement and sustains structural plasticity. The WAVE Regulatory Complex (WRC), a pivotal branched actin regulator, controls spine morphology and therefore structural plasticity. However, the molecular mechanisms that govern WRC activation during spine enlargement are largely unknown. Here we identify a critical role for Neogenin and its ligand RGMa (Repulsive Guidance Molecule a) in promoting spine enlargement through the activation of WRC-mediated branched actin remodeling. We demonstrate that Neogenin regulates WRC activity by binding to the highly conserved Cyfip/Abi binding pocket within the WRC. We find that after Neogenin or RGMa depletion, the proportions of filopodia and immature thin spines are dramatically increased, and the number of mature mushroom spines concomitantly decreased. Wildtype Neogenin, but not Neogenin bearing mutations in the Cyfip/Abi binding motif, is able to rescue the spine enlargement defect. Furthermore, Neogenin depletion inhibits actin polymerization in the spine head, an effect that is not restored by the mutant. We conclude that RGMa and Neogenin are critical modulators of WRC-mediated branched actin polymerization promoting spine enlargement. This study also provides mechanistic insight into Neogenin's emerging role in LTP induction.
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Affiliation(s)
- Kai Sempert
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Belal Shohayeb
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Vanessa Lanoue
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Elizabeth A O'Brien
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Cecilia Flores
- Department of Psychiatry, McGill University, Montréal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
- Douglas Mental Health University Institute, Montréal, QC, Canada
| | - Helen M Cooper
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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2
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Nickerson KR, Tom I, Cortés E, Abolafia JR, Özkan E, Gonzalez LC, Jaworski A. WFIKKN2 is a bifunctional axon guidance cue that signals through divergent DCC family receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.15.544950. [PMID: 37398498 PMCID: PMC10312737 DOI: 10.1101/2023.06.15.544950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Axon pathfinding is controlled by attractive and repulsive molecular cues that activate receptors on the axonal growth cone, but the full repertoire of axon guidance molecules remains unknown. The vertebrate DCC receptor family contains the two closely related members DCC and Neogenin with prominent roles in axon guidance and three additional, divergent members - Punc, Nope, and Protogenin - for which functions in neural circuit formation have remained elusive. We identified a secreted Punc/Nope/Protogenin ligand, WFIKKN2, which guides mouse peripheral sensory axons through Nope-mediated repulsion. In contrast, WFIKKN2 attracts motor axons, but not via Nope. These findings identify WFIKKN2 as a bifunctional axon guidance cue that acts through divergent DCC family members, revealing a remarkable diversity of ligand interactions for this receptor family in nervous system wiring. One-Sentence Summary WFIKKN2 is a ligand for the DCC family receptors Punc, Nope, and Prtg that repels sensory axons and attracts motor axons.
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Neogenin suppresses tumor progression and metastasis via inhibiting Merlin/YAP signaling. Cell Death Dis 2023; 9:47. [PMID: 36746934 PMCID: PMC9902585 DOI: 10.1038/s41420-023-01345-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 02/08/2023]
Abstract
From in situ growth to invasive dissemination is the most lethal attribute of various tumor types. This transition is majorly mediated by the dynamic interplay between two cancer hallmarks, EMT and cell cycle. In this study, we applied nonlinear association analysis in 33 cancer types and found that most signaling receptors simultaneously associating with EMT and cell cycle are potential tumor suppressors. Here we find that a top co-associated receptor, Neogenin (NEO1), inhibits colorectal cancer (CRC) and Glioma in situ growth and metastasis by forming a complex with Merlin (NF2), and subsequent simultaneous promoting the phosphorylation of YAP. Furthermore, Neogenin protein level is associated with good prognosis and correlates with Merlin status in CRC and Glioma. Collectively, our results define Neogenin as a tumor suppressor in CRC and Glioma that acts by restricting oncogenic signaling by the Merlin-YAP pathway, and suggest Neogenin as a candidate therapeutic agent for CRC and Glioma.
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4
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González-Llera L, Shifman MI, Barreiro-Iglesias A. Neogenin expression in ependymo-radial glia of the larval sea lamprey Petromyzon marinus spinal cord. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000810. [PMID: 37143448 PMCID: PMC10152269 DOI: 10.17912/micropub.biology.000810] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 04/05/2023] [Accepted: 04/10/2023] [Indexed: 05/06/2023]
Abstract
Neogenin is a receptor mainly known for its roles during axon pathfinding. However, neogenin is expressed in neuronal precursors of ventricular and subventricular zones of the nervous system and recent work has shown that it regulates adult neurogenesis. Here, we generated an antibody against the sea lamprey neogenin to study its expression in the larval spinal cord. Immunofluorescence experiments show that neogenin is expressed in ependymo-radial glial cells (ERGs) located in the ependymal region of the central canal of mature larval sea lampreys. Our results provide a basis for the future study of the role of neogenin in lamprey ERGs.
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Affiliation(s)
- Laura González-Llera
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
| | | | - Antón Barreiro-Iglesias
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
- Correspondence to: Antón Barreiro-Iglesias (
)
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5
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Kanlayaprasit S, Thongkorn S, Panjabud P, Jindatip D, Hu VW, Kikkawa T, Osumi N, Sarachana T. Autism-Related Transcription Factors Underlying the Sex-Specific Effects of Prenatal Bisphenol A Exposure on Transcriptome-Interactome Profiles in the Offspring Prefrontal Cortex. Int J Mol Sci 2021; 22:13201. [PMID: 34947998 PMCID: PMC8708761 DOI: 10.3390/ijms222413201] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/03/2021] [Accepted: 12/05/2021] [Indexed: 11/16/2022] Open
Abstract
Bisphenol A (BPA) is an environmental risk factor for autism spectrum disorder (ASD). BPA exposure dysregulates ASD-related genes in the hippocampus and neurological functions of offspring. However, whether prenatal BPA exposure has an impact on genes in the prefrontal cortex, another brain region highly implicated in ASD, and through what mechanisms have not been investigated. Here, we demonstrated that prenatal BPA exposure disrupts the transcriptome-interactome profiles of the prefrontal cortex of neonatal rats. Interestingly, the list of BPA-responsive genes was significantly enriched with known ASD candidate genes, as well as genes that were dysregulated in the postmortem brain tissues of ASD cases from multiple independent studies. Moreover, several differentially expressed genes in the offspring's prefrontal cortex were the targets of ASD-related transcription factors, including AR, ESR1, and RORA. The hypergeometric distribution analysis revealed that BPA may regulate the expression of such genes through these transcription factors in a sex-dependent manner. The molecular docking analysis of BPA and ASD-related transcription factors revealed novel potential targets of BPA, including RORA, SOX5, TCF4, and YY1. Our findings indicated that prenatal BPA exposure disrupts ASD-related genes in the offspring's prefrontal cortex and may increase the risk of ASD through sex-dependent molecular mechanisms, which should be investigated further.
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Grants
- FRB65_hea(80)_175_37_05 Fundamental Fund, Chulalongkorn University
- AHS-CU 61004 Faculty of Allied Health Sciences Research Fund, Chulalongkorn University
- GRU 6300437001-1 Ratchadapisek Somphot Fund for Supporting Research Unit, Chulalongkorn University
- GRU_64_033_37_004 Ratchadapisek Somphot Fund for Supporting Research Unit, Chulalongkorn University
- The 100th Anniversary Chulalongkorn University Fund for Doctoral Scholarship, Graduate School, Chulalongkorn University
- The Overseas Research Experience Scholarship for Graduate Students from Graduate School, Chulalongkorn University
- PHD/0029/2561 The Royal Golden Jubilee Ph.D. Programme Scholarship, Thailand Research Fund and National Research Council of Thailand
- National Research Council of Thailand (NRCT)
- GCUGR1125623067D-67 The 90th Anniversary Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund), Graduate School, Chulalongkorn University
- GCUGR1125632108D-108 The 90th Anniversary Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund), Graduate School, Chulalongkorn University
- 2073011 Chulalongkorn University Laboratory Animal Center (CULAC) Grant
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Affiliation(s)
- Songphon Kanlayaprasit
- The Ph.D. Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand; (S.K.); (S.T.); (P.P.)
| | - Surangrat Thongkorn
- The Ph.D. Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand; (S.K.); (S.T.); (P.P.)
| | - Pawinee Panjabud
- The Ph.D. Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand; (S.K.); (S.T.); (P.P.)
| | - Depicha Jindatip
- Systems Neuroscience of Autism and PSychiatric Disorders (SYNAPS) Research Unit, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand;
- Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Valerie W. Hu
- Department of Biochemistry and Molecular Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20052, USA;
| | - Takako Kikkawa
- Department of Developmental Neuroscience, United Centers for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, Sendai 980-8577, Miyagi, Japan; (T.K.); (N.O.)
| | - Noriko Osumi
- Department of Developmental Neuroscience, United Centers for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, Sendai 980-8577, Miyagi, Japan; (T.K.); (N.O.)
| | - Tewarit Sarachana
- Systems Neuroscience of Autism and PSychiatric Disorders (SYNAPS) Research Unit, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand;
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Robinson RA, Griffiths SC, van de Haar LL, Malinauskas T, van Battum EY, Zelina P, Schwab RA, Karia D, Malinauskaite L, Brignani S, van den Munkhof MH, Düdükcü Ö, De Ruiter AA, Van den Heuvel DMA, Bishop B, Elegheert J, Aricescu AR, Pasterkamp RJ, Siebold C. Simultaneous binding of Guidance Cues NET1 and RGM blocks extracellular NEO1 signaling. Cell 2021; 184:2103-2120.e31. [PMID: 33740419 PMCID: PMC8063088 DOI: 10.1016/j.cell.2021.02.045] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 01/15/2021] [Accepted: 02/22/2021] [Indexed: 12/13/2022]
Abstract
During cell migration or differentiation, cell surface receptors are simultaneously exposed to different ligands. However, it is often unclear how these extracellular signals are integrated. Neogenin (NEO1) acts as an attractive guidance receptor when the Netrin-1 (NET1) ligand binds, but it mediates repulsion via repulsive guidance molecule (RGM) ligands. Here, we show that signal integration occurs through the formation of a ternary NEO1-NET1-RGM complex, which triggers reciprocal silencing of downstream signaling. Our NEO1-NET1-RGM structures reveal a "trimer-of-trimers" super-assembly, which exists in the cell membrane. Super-assembly formation results in inhibition of RGMA-NEO1-mediated growth cone collapse and RGMA- or NET1-NEO1-mediated neuron migration, by preventing formation of signaling-compatible RGM-NEO1 complexes and NET1-induced NEO1 ectodomain clustering. These results illustrate how simultaneous binding of ligands with opposing functions, to a single receptor, does not lead to competition for binding, but to formation of a super-complex that diminishes their functional outputs.
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Affiliation(s)
- Ross A Robinson
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Samuel C Griffiths
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lieke L van de Haar
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Eljo Y van Battum
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Pavol Zelina
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Rebekka A Schwab
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Dimple Karia
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lina Malinauskaite
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sara Brignani
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Marleen H van den Munkhof
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Özge Düdükcü
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Anna A De Ruiter
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Dianne M A Van den Heuvel
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Jonathan Elegheert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
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Hippocampal astrocytic neogenin regulating glutamate uptake, a critical pathway for preventing epileptic response. Proc Natl Acad Sci U S A 2021; 118:2022921118. [PMID: 33850017 DOI: 10.1073/pnas.2022921118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epilepsy, a common neurological disorder, is featured with recurrent seizures. Its underlying pathological mechanisms remain elusive. Here, we provide evidence for loss of neogenin (NEO1), a coreceptor for multiple ligands, including netrins and bone morphological proteins, in the development of epilepsy. NEO1 is reduced in hippocampi from patients with epilepsy based on transcriptome and proteomic analyses. Neo1 knocking out (KO) in mouse brains displays elevated epileptiform spikes and seizure susceptibility. These phenotypes were undetectable in mice, with selectively depleted NEO1 in excitatory (NeuroD6-Cre+) or inhibitory (parvalbumin+) neurons, but present in mice with specific hippocampal astrocytic Neo1 KO. Additionally, neurons in hippocampal dentate gyrus, a vulnerable region in epilepsy, in mice with astrocyte-specific Neo1 KO show reductions in inhibitory synaptic vesicles and the frequency of miniature inhibitory postsynaptic current(mIPSC), but increase of the duration of miniature excitatory postsynaptic current and tonic NMDA receptor currents, suggesting impairments in both GABAergic transmission and extracellular glutamate clearance. Further proteomic and cell biological analyses of cell-surface proteins identified GLAST, a glutamate-aspartate transporter that is marked reduced in Neo1 KO astrocytes and the hippocampus. NEO1 interacts with GLAST and promotes GLAST surface distribution in astrocytes. Expressing NEO1 or GLAST in Neo1 KO astrocytes in the hippocampus abolishes the epileptic phenotype. Taken together, these results uncover an unrecognized pathway of NEO1-GLAST in hippocampal GFAP+ astrocytes, which is critical for GLAST surface distribution and function, and GABAergic transmission, unveiling NEO1 as a valuable therapeutic target to protect the brain from epilepsy.
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8
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Ren X, Yao LL, Pan JX, Zhang JS, Mei L, Wang YG, Xiong WC. Linking cortical astrocytic neogenin deficiency to the development of Moyamoya disease-like vasculopathy. Neurobiol Dis 2021; 154:105339. [PMID: 33775822 DOI: 10.1016/j.nbd.2021.105339] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/02/2021] [Accepted: 03/17/2021] [Indexed: 02/06/2023] Open
Abstract
Moyamoya-like vasculopathy, the "puff of smoke"-like small vessels in the brain, is initially identified in patients with Moyamoya disease (MMD), a rare cerebrovascular disease, and later found in patients with various types of neurological conditions, including Down syndrome, Stroke, and vascular dementia. It is thus of interest to understand how this vasculopathy is developed. Here, we provided evidence for cortical astrocytic neogenin (NEO1) deficiency to be a risk factor for its development. NEO1, a member of deleted in colorectal cancer (DCC) family netrin receptors, was reduced in brain samples of patients with MMD. Astrocytic Neo1-loss resulted in an increase of small blood vessels (BVs) selectively in the cortex. These BVs were dysfunctional, with leaky blood-brain barrier (BBB), thin arteries, and accelerated hyperplasia in veins and capillaries, resembled to the features of moyamoya-like vasculopathy. Additionally, we found that both MMD patient and Neo1 mutant mice exhibited altered gene expression in their cortex in proteins critical for not only angiogenesis [e.g., an increase in vascular endothelial growth factor (VEGFa)], but also axon guidance (e.g., netrin family proteins) and inflammation. In aggregates, these results suggest a critical role of astrocytic NEO1-loss in the development of Moyamoya-like vasculopathy, providing a mouse model for investigating mechanisms of Moyamoya-like vasculopathy.
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Affiliation(s)
- Xiao Ren
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Ling-Ling Yao
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Jin-Xiu Pan
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Jun-Shi Zhang
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Lin Mei
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Yong-Gang Wang
- Department of Neurology, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China; Beijing Tiantan Hospital, Capital Medical University, No.119, S 4th Ring W Rd, Fengtai District, Beijing 100070, China.
| | - Wen-Cheng Xiong
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA.
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9
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Identification of NEO1 as a prognostic biomarker and its effects on the progression of colorectal cancer. Cancer Cell Int 2020; 20:510. [PMID: 33088218 PMCID: PMC7568410 DOI: 10.1186/s12935-020-01604-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 10/12/2020] [Indexed: 11/20/2022] Open
Abstract
Background Due to the high morbidity and poor clinical outcomes, early predictive and prognostic biomarker identification is desiderated in colorectal cancer (CRC). As a homologue of the Deleted in Colorectal Cancer (DCC) gene, the role of Neogenin-1 (NEO1) in CRC remained unveiled. This study was designed to probe into the effects and potential function of NEO1 in CRC. Methods Online databases, Gene Set Enrichment Analysis (GSEA), quantitative real-time PCR and western blotting were used to evaluate NEO1 expression in colorectal cancer tissues. Survival analysis was performed to predict the prognosis of CRC patients based on NEO1 expression level. Then, cell proliferation was detected by colony formation and Cell Counting Kit 8 (CCK-8) assays. CRC cell migration and invasion were examined by transwell assays. Finally, we utilized the Gene Set Variation Analysis (GSVA) and GSEA to dig the potential mechanisms of NEO1 in CRC. Results Oncomine database and The Cancer Genome Atlas (TCGA) database showed that NEO1 was down-regulated in CRC. Further results validated that NEO1 mRNA and protein expression were both significantly lower in CRC tumor tissues than in the adjacent tissues in our clinical samples. NEO1 expression was decreased with the progression of CRC. Survival and other clinical characteristic analyses exhibited that low NEO1 expression was related with poor prognosis. A gain-of-function study showed that overexpression of NEO1 restrained proliferation, migration and invasion of CRC cells while a loss-of-function showed the opposite effects. Finally, functional pathway enrichment analysis revealed that NEO1 low expression samples were enriched in inflammation-related signaling pathways, EMT and angiogenesis. Conclusion A tumor suppressor gene NEO1 was identified and verified to be correlated with the prognosis and progression of CRC, which could serve as a prognostic biomarker for CRC patients.
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10
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Isaksen TJ, Yamashita T. Repulsive Guidance Molecule A Regulates Adult Neurogenesis Via the Neogenin Receptor. Neurosci Insights 2020; 15:2633105520948481. [PMID: 32864618 PMCID: PMC7430068 DOI: 10.1177/2633105520948481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 07/20/2020] [Indexed: 12/21/2022] Open
Abstract
Repulsive guidance molecule A (RGMa) exhibits repulsive guidance of axonal growth and regulates neuronal differentiation during development of the mammalian brain. In this commentary, we describe the findings of our recent paper, "Repulsive Guidance Molecule A Suppresses Adult Neurogenesis," and discuss a possible model for RGMa suppression of newborn neurons that fail to properly migrate into the granular cell layer. In the study, we provided evidence that RGMa suppressed neurite growth and survival of newborn neurons in the adult dentate gyrus. This effect depends on the multifunctional Neogenin receptor expressed in adult neural stem cells through activation of the Rho-associated protein kinase leading to neurite growth inhibition and ultimately cell death. It should be noted that both RGMa and Neogenin interact with several well-described molecules, including bone morphogenetic proteins, that regulate neuronal development. Thus, it is likely that RGMa interacts with other intricate molecular networks that regulate adult neurogenesis.
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Affiliation(s)
- Toke Jost Isaksen
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan.,WPI Immunology Frontier Research Center, Osaka University, Suita, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, Suita, Japan
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11
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Liu Y, Zhang Y, Zarrei M, Dong R, Yang X, Zhao D, Scherer SW, Gai Z. Refining critical regions in 15q24 microdeletion syndrome pertaining to autism. Am J Med Genet B Neuropsychiatr Genet 2020; 183:217-226. [PMID: 31953991 DOI: 10.1002/ajmg.b.32778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 11/29/2019] [Accepted: 12/16/2019] [Indexed: 12/26/2022]
Abstract
Chromosome 15q24 microdeletion syndrome is characterized by developmental delay, facial dysmorphism, hearing loss, hypotonia, recurrent infection, and other congenital malformations including microcephaly, scoliosis, joint laxity, digital anomalies, as well as sometimes having autism spectrum disorder (ASD) and attention deficit hyperactivity disorder. Here, we report a boy with a 2.58-Mb de novo deletion at chromosome 15q24. He is diagnosed with ASD and having multiple phenotypes similar to those reported in cases having 15q24 microdeletion syndrome. To delineate the critical genes and region that might be responsible for these phenotypes, we reviewed all previously published cases. We observe a potential minimum critical region of 650 kb (LCR15q24A-B) affecting NEO1 among other genes that might pertinent to individuals with ASD carrying this deletion. In contrast, a previously defined minimum critical region downstream of the 650-kb interval (LCR15q24B-D) is more likely associated with the developmental delay, facial dysmorphism, recurrent infection, and other congenital malformations. As a result, the ASD phenotype in this individual is potentially attributed by genes particularly NEO1 within the newly proposed critical region.
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Affiliation(s)
- Yi Liu
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, Ji'nan, China
| | - Yanqing Zhang
- Pediatric Health Care Institute, Qilu Children's Hospital of Shandong University, Ji'nan, 250022, China
| | - Mehdi Zarrei
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Rui Dong
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, Ji'nan, China
| | - Xiaomeng Yang
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, Ji'nan, China
| | - Dongmei Zhao
- Pediatric Health Care Institute, Qilu Children's Hospital of Shandong University, Ji'nan, 250022, China
| | - Stephen W Scherer
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada.,McLaughlin Centre and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Zhongtao Gai
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, Ji'nan, China
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12
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Liu Y, Mapow B. Coexistence of urogenital malformations in a female fetus with de novo 15q24 microdeletion and a literature review. Mol Genet Genomic Med 2020; 8:e1265. [PMID: 32400031 PMCID: PMC7336734 DOI: 10.1002/mgg3.1265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Abstract
Background 15q24 microdeletion is a relatively new syndrome caused by nonallelic homologous recombination (NAHR) between low‐copy repeats (LCRs) in the 15q24 chromosome region. This syndrome is characterized by a spectrum of clinical symptoms including global developmental delay, intellectual disability, facial dysmorphisms, and congenital malformations of the extremities, eye, gastrointestinal tract, genitourinary system, and genitalia. Method Molecular cytogenetic analysis was performed using whole genome single‐nucleotide polymorphism (SNP) microarray analysis. Autopsy examination including gross and microscopic examination were performed. In addition, a thorough review of the literature on 15q24 microdeletion was completed and summarized in table format. Result Molecular cytogenetic analysis revealed a 3.88 MB interstitial deletion within 15q24.1 to 15q24.3 (74,353,735–78,228,485 bp) in our case. Autopsy examination showed congenital malformations within the genitourinary system and genitalia, including left kidney agenesis and uterus didelphys. After thorough literature review, we found a series of midline defects associated with 15q24 microdeletion syndrome. Conclusion We report the first case of coexistence of urogenital abnormalities, including left kidney agenesis and uterus didelphys, with 15q24 microdeletion syndrome, which is also associated with midline defects secondary to abnormal development. Since 15q24 microdeletion syndrome is a relatively new entity, fully characterizing its variation and severity requires additional examination of the genetics, molecular profile and structural and functional abnormalities in affected patients. Due to the limited data in the literature, statistical analysis of abnormalities in each organ system is not possible. However, we can predict that novel genetic pathways involving cell migration, adhesion, apoptosis, and embryo development might be discovered with the advanced study of 15q24 microdeletion syndrome.
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Affiliation(s)
- Yaobin Liu
- Department of Pathology, Pennsylvania Hospital, Philadelphia, Pennsylvania, USA
| | - Beth Mapow
- Department of Pathology and Laboratory Medicine, Jefferson Health New jersey, Cherry Hill, New Jersey, USA
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13
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Isaksen TJ, Fujita Y, Yamashita T. Repulsive Guidance Molecule A Suppresses Adult Neurogenesis. Stem Cell Reports 2020; 14:677-691. [PMID: 32243839 PMCID: PMC7160374 DOI: 10.1016/j.stemcr.2020.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/03/2020] [Accepted: 03/03/2020] [Indexed: 01/17/2023] Open
Abstract
Repulsive guidance molecule A (RGMa) is a glycosylphosphatidylinositol-anchored glycoprotein that exhibits repulsive neurite guidance and regulates neuronal differentiation and survival during brain development. However, the function of RGMa in the adult brain is unknown. Here, we show that RGMa is expressed in the adult hippocampus and provide evidence that RGMa signaling suppresses adult neurogenesis. Knockdown of RGMa in the dentate gyrus increased the number of surviving newborn neurons; however, these cells failed to properly migrate into the granular cell layer. In vitro, RGMa stimulation of adult neural stem cells suppressed neurite outgrowth of newborn neurons, which could be prevented by knockdown of the multifunctional receptor neogenin, as well as pharmacological inhibition of the downstream target Rho-associated protein kinase. These findings present a function for RGMa in the adult brain and add to the intricate molecular network that regulates adult brain plasticity. RGMa suppress survival and growth of newborn neurons in the adult dentate gyrus RGMa signaling depends on neogenin for the regulation of adult neurogenesis RGMa induces RhoA/ROCK activation in adult neuronal stem cells
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Affiliation(s)
- Toke Jost Isaksen
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuki Fujita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Graduate School of Frontier Bioscience, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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14
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Lin S, Liu W, Chen CL, Sun D, Hu JX, Li L, Ye J, Mei L, Xiong WC. Neogenin-loss in neural crest cells results in persistent hyperplastic primary vitreous formation. J Mol Cell Biol 2020; 12:17-31. [PMID: 31336386 PMCID: PMC7053014 DOI: 10.1093/jmcb/mjz076] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/07/2019] [Accepted: 06/12/2019] [Indexed: 01/25/2023] Open
Abstract
Neogenin is a transmembrane receptor critical for multiple cellular processes, including neurogenesis, astrogliogenesis, endochondral bone formation, and iron homeostasis. Here we present evidence that loss of neogenin contributes to pathogenesis of persistent hyperplastic primary vitreous (PHPV) formation, a genetic disorder accounting for ~ 5% of blindness in the USA. Selective loss of neogenin in neural crest cells (as observed in Wnt1-Cre; Neof/f mice), but not neural stem cells (as observed in GFAP-Cre and Nestin-Cre; Neof/f mice), resulted in a dysregulation of neural crest cell migration or delamination, exhibiting features of PHPV-like pathology (e.g. elevated retrolental mass), unclosed retinal fissure, and microphthalmia. These results demonstrate an unrecognized function of neogenin in preventing PHPV pathogenesis, implicating neogenin regulation of neural crest cell delamination/migration and retinal fissure formation as potential underlying mechanisms of PHPV.
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Affiliation(s)
- Sen Lin
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
- Department of Ophthalmology, Daping Hospital, Army Medical Center of PLA, Chongqing, China
| | - Wei Liu
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
- Department of Ophthalmology, Daping Hospital, Army Medical Center of PLA, Chongqing, China
| | - Chun-Lin Chen
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
- Department of Ophthalmology, Daping Hospital, Army Medical Center of PLA, Chongqing, China
| | - Dong Sun
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Jin-Xia Hu
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
| | - Lei Li
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
| | - Jian Ye
- Department of Ophthalmology, Daping Hospital, Army Medical Center of PLA, Chongqing, China
| | - Lin Mei
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wen-Cheng Xiong
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA 30912, USA
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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15
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Gulati GS, Zukowska M, Noh JJ, Zhang A, Wesche DJ, Sinha R, George BM, Weissman IL, Szade K. Neogenin-1 distinguishes between myeloid-biased and balanced Hoxb5+ mouse long-term hematopoietic stem cells. Proc Natl Acad Sci U S A 2019; 116:25115-25125. [PMID: 31754028 PMCID: PMC6911217 DOI: 10.1073/pnas.1911024116] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hematopoietic stem cells (HSCs) self-renew and generate all blood cells. Recent studies with single cell transplants and lineage tracing suggest that adult HSCs are diverse in their reconstitution and lineage potentials. However, prospective isolation of these subpopulations has remained challenging. Here, we identify Neogenin-1 (NEO1) as a unique surface marker on a fraction of mouse HSCs labeled with Hoxb5, a specific reporter of long-term HSCs (LT-HSCs). We show that NEO1+Hoxb5+ LT-HSCs expand with age and respond to myeloablative stress in young mice while NEO1-Hoxb5+ LT-HSCs exhibit no significant change in number. Furthermore, NEO1+Hoxb5+ LT-HSCs are more often in the G2/S cell cycle phase compared to NEO1-Hoxb5+ LT-HSCs in both young and old bone marrow. Upon serial transplantation, NEO1+Hoxb5+ LT-HSCs exhibit myeloid-biased differentiation and reduced reconstitution while NEO1-Hoxb5+ LT-HSCs are lineage-balanced and stably reconstitute recipients. Gene expression analysis reveals erythroid and myeloid priming in the NEO1+ fraction and association of quiescence and self-renewal-related transcription factors with NEO1- LT-HSCs. Finally, transplanted NEO1+Hoxb5+ LT-HSCs rarely generate NEO1-Hoxb5+ LT-HSCs while NEO1-Hoxb5+ LT-HSCs repopulate both LT-HSC fractions. This supports a model in which dormant, balanced NEO1-Hoxb5+ LT-HSCs can hierarchically precede active, myeloid-biased NEO1+Hoxb5+ LT-HSCs.
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Affiliation(s)
- Gunsagar S Gulati
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
| | - Monika Zukowska
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
| | - Joseph J Noh
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
| | - Allison Zhang
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
| | - Daniel J Wesche
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
| | - Rahul Sinha
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
| | - Benson M George
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305
| | - Irving L Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305;
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Krzysztof Szade
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305;
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
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Culjat M, Milošević NJ. Callosal septa express guidance cues and are paramedian guideposts for human corpus callosum development. J Anat 2019; 235:670-686. [PMID: 31070791 PMCID: PMC6704273 DOI: 10.1111/joa.13011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2019] [Indexed: 12/18/2022] Open
Abstract
The early development and growth of the corpus callosum are supported by several midline transient structures in mammals that include callosal septa (CS), which are present only in the second half of gestation in humans. Here we provide new data that support the guidance role of CS in corpus callosum development, derived from the analysis of 46 postmortem fetal brains, ranging in age from 16 to 40 post conception weeks (PCW). Using immunohistochemical methods, we show the expression pattern of guidance cues ephrinA4 and neogenin, extracellular protein fibronectin, as well as non-activated microglia in the CS. We found that the dynamic changes in expression of guidance cues, cellular and extracellular matrix constituents in the CS correlate well with the growth course of the corpus callosum at midsagittal level. The CS reach and maintain their developmental maximum between 20 and 26 PCW and can be visualized as hypointense structures in the ventral callosal portion with ex vivo (in vitro) T2-weighted 3T magnetic resonance imaging (MRI). The maximum of septal development overlaps with an increase in the callosal midsagittal area, whereas the slow, gradual resolution of CS coincides with a plateau of midsagittal callosal growth. The recognition of CS existence in human fetal brain and the ability to visualize them by ex vivoMRI attributes a potential diagnostic value to these transient structures, as advancement in imaging technologies will likely also enable in vivoMRI visualization of the CS in the near future.
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Affiliation(s)
- Marko Culjat
- MedStar Georgetown University HospitalWashingtonDCUSA
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17
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Rgma-Induced Neo1 Proteolysis Promotes Neural Tube Morphogenesis. J Neurosci 2019; 39:7465-7484. [PMID: 31399534 DOI: 10.1523/jneurosci.3262-18.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 07/01/2019] [Accepted: 07/31/2019] [Indexed: 01/02/2023] Open
Abstract
Neuroepithelial cell (NEC) elongation is one of several key cell behaviors that mediate the tissue-level morphogenetic movements that shape the neural tube (NT), the precursor of the brain and spinal cord. However, the upstream signals that promote NEC elongation have been difficult to tease apart from those regulating apico-basal polarity and hingepoint formation, due to their confounding interdependence. The Repulsive Guidance Molecule a (Rgma)/Neogenin 1 (Neo1) signaling pathway plays a conserved role in NT formation (neurulation) and is reported to regulate both NEC elongation and apico-basal polarity, through signal transduction events that have not been identified. We examine here the role of Rgma/Neo1 signaling in zebrafish (sex unknown), an organism that does not use hingepoints to shape its hindbrain, thereby enabling a direct assessment of the role of this pathway in NEC elongation. We confirm that Rgma/Neo1 signaling is required for microtubule-mediated NEC elongation, and demonstrate via cell transplantation that Neo1 functions cell autonomously to promote elongation. However, in contrast to previous findings, our data do not support a role for this pathway in establishing apical junctional complexes. Last, we provide evidence that Rgma promotes Neo1 glycosylation and intramembrane proteolysis, resulting in the production of a transient, nuclear intracellular fragment (NeoICD). Partial rescue of Neo1a and Rgma knockdown embryos by overexpressing neoICD suggests that this proteolytic cleavage is essential for neurulation. Based on these observations, we propose that RGMA-induced NEO1 proteolysis orchestrates NT morphogenesis by promoting NEC elongation independently of the establishment of apical junctional complexes.SIGNIFICANCE STATEMENT The neural tube, the CNS precursor, is shaped during neurulation. Neural tube defects occur frequently, yet underlying genetic risk factors are poorly understood. Neuroepithelial cell (NEC) elongation is essential for proper completion of neurulation. Thus, connecting NEC elongation with the molecular pathways that control this process is expected to reveal novel neural tube defect risk factors and increase our understanding of NT development. Effectors of cell elongation include microtubules and microtubule-associated proteins; however, upstream regulators remain controversial due to the confounding interdependence of cell elongation and establishment of apico-basal polarity. Here, we reveal that Rgma-Neo1 signaling controls NEC elongation independently of the establishment of apical junctional complexes and identify Rgma-induced Neo1 proteolytic cleavage as a key upstream signaling event.
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18
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Jaminet P, Schäufele M, Mager A, Fornaro M, Ronchi G, Geuna S, Schaller HE, Rosenberger P, Köhler D. Expression patterns and functional evaluation of RGMa during the early phase of peripheral nerve regeneration using the mouse median nerve model. Restor Neurol Neurosci 2019; 37:265-272. [PMID: 31177252 DOI: 10.3233/rnn-190913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND In this study, we evaluate the role of RGMa (Repulsive Guidance Molecule a) during peripheral nerve regeneration using the mouse median nerve model. METHODS By real-time PCR and Western Blot analysis, we examined expression changes of RGMa mRNA and RGMa protein in neural tissue after transection and microsurgical repair of the mouse median nerve distal to the transection site. We evaluated histomorphometrical changes in neural tissue distal to the injury site and functional recovery of the grasping force after median nerve transection and repair in wild-type mice and RGMa+/- heterozygous mice. RESULTS RT-PCR revealed a 1,8 fold increase of RGMa mRNA two weeks and a 4,4 fold increase of RGMa mRNA 3 weeks after nerve transection and repair in the nerve segment distal to the injury site. In Western blot analysis, we could show a high increase of RGMa in the nerve segment distal to the injury site at day 14. Histomorphometrical analysis showed significant differences between wild-type animals and heterozygous animals. The absolute number of myelinated fibres was significantly higher in operated heterozygous RGMa+/- animals compared to operated wildtye animals. Using the functional grasping test, we could demonstrate that peripheral nerve regeneration is significantly diminished in heterozygous RGMa+/- mice. CONCLUSIONS Employing the mouse median nerve model in transgenic animals, we demonstrate that RGMa plays an important role during peripheral nerve regeneration.
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Affiliation(s)
- Patrick Jaminet
- Department of Plastic Surgery and Hand Surgery, Klinikum Westmünsterland, Borken, Germany
| | - Martin Schäufele
- Department of Plastic, Hand and Reconstructive Surgery, Burn Center, BG-Trauma Center, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Alice Mager
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Tübingen, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Michele Fornaro
- Dipartimento di Scienze Cliniche e Biologiche & Neuroscience Institute Cavalieri Ottolenghi, Università di Torino, Italy
| | - Giulia Ronchi
- Dipartimento di Scienze Cliniche e Biologiche & Neuroscience Institute Cavalieri Ottolenghi, Università di Torino, Italy
| | - Stefano Geuna
- Dipartimento di Scienze Cliniche e Biologiche & Neuroscience Institute Cavalieri Ottolenghi, Università di Torino, Italy
| | - Hans-Eberhard Schaller
- Department of Plastic, Hand and Reconstructive Surgery, Burn Center, BG-Trauma Center, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Peter Rosenberger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Tübingen, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - David Köhler
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Tübingen, Eberhard Karls University of Tübingen, Tübingen, Germany
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19
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Ranaivoson FM, Turk LS, Ozgul S, Kakehi S, von Daake S, Lopez N, Trobiani L, De Jaco A, Denissova N, Demeler B, Özkan E, Montelione GT, Comoletti D. A Proteomic Screen of Neuronal Cell-Surface Molecules Reveals IgLONs as Structurally Conserved Interaction Modules at the Synapse. Structure 2019; 27:893-906.e9. [PMID: 30956130 DOI: 10.1016/j.str.2019.03.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/10/2019] [Accepted: 03/07/2019] [Indexed: 12/21/2022]
Abstract
In the developing brain, cell-surface proteins play crucial roles, but their protein-protein interaction network remains largely unknown. A proteomic screen identified 200 interactions, 89 of which were not previously published. Among these interactions, we find that the IgLONs, a family of five cell-surface neuronal proteins implicated in various human disorders, interact as homo- and heterodimers. We reveal their interaction patterns and report the dimeric crystal structures of Neurotrimin (NTRI), IgLON5, and the neuronal growth regulator 1 (NEGR1)/IgLON5 complex. We show that IgLONs maintain an extended conformation and that their dimerization occurs through the first Ig domain of each monomer and is Ca2+ independent. Cell aggregation shows that NTRI and NEGR1 homo- and heterodimerize in trans. Taken together, we report 89 unpublished cell-surface ligand-receptor pairs and describe structural models of trans interactions of IgLONs, showing that their structures are compatible with a model of interaction across the synaptic cleft.
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Affiliation(s)
| | - Liam S Turk
- Child Health Institute of New Jersey, New Brunswick, NJ 08901, USA
| | - Sinem Ozgul
- Child Health Institute of New Jersey, New Brunswick, NJ 08901, USA
| | - Sumie Kakehi
- Child Health Institute of New Jersey, New Brunswick, NJ 08901, USA
| | | | - Nicole Lopez
- Child Health Institute of New Jersey, New Brunswick, NJ 08901, USA
| | - Laura Trobiani
- Department of Biology and Biotechnology "Charles Darwin" and Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Antonella De Jaco
- Department of Biology and Biotechnology "Charles Darwin" and Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Natalia Denissova
- Department of Molecular Biology and Biochemistry and Center for Advanced Biotechnology and Medicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Gaetano T Montelione
- Department of Molecular Biology and Biochemistry and Center for Advanced Biotechnology and Medicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Davide Comoletti
- Child Health Institute of New Jersey, New Brunswick, NJ 08901, USA; Departments of Neuroscience and Cell Biology Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA; Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA; School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
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20
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Boyer NP, Gupton SL. Revisiting Netrin-1: One Who Guides (Axons). Front Cell Neurosci 2018; 12:221. [PMID: 30108487 PMCID: PMC6080411 DOI: 10.3389/fncel.2018.00221] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 07/09/2018] [Indexed: 12/28/2022] Open
Abstract
Proper patterning of the nervous system requires that developing axons find appropriate postsynaptic partners; this entails microns to meters of extension through an extracellular milieu exhibiting a wide range of mechanical and chemical properties. Thus, the elaborate networks of fiber tracts and non-fasciculated axons evident in mature organisms are formed via complex pathfinding. The macroscopic structures of axon projections are highly stereotyped across members of the same species, indicating precise mechanisms guide their formation. The developing axon exhibits directionally biased growth toward or away from external guidance cues. One of the most studied guidance cues is netrin-1, however, its presentation in vivo remains debated. Guidance cues can be secreted to form soluble or chemotactic gradients or presented bound to cells or the extracellular matrix to form haptotactic gradients. The growth cone, a highly specialized dynamic structure at the end of the extending axon, detects these guidance cues via transmembrane receptors, such as the netrin-1 receptors deleted in colorectal cancer (DCC) and UNC5. These receptors orchestrate remodeling of the cytoskeleton and cell membrane through both chemical and mechanotransductive pathways, which result in traction forces generated by the cytoskeleton against the extracellular environment and translocation of the growth cone. Through intracellular signaling responses, netrin-1 can trigger either attraction or repulsion of the axon. Here we review the mechanisms by which the classical guidance cue netrin-1 regulates intracellular effectors to respond to the extracellular environment in the context of axon guidance during development of the central nervous system and discuss recent findings that demonstrate the critical importance of mechanical forces in this process.
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Affiliation(s)
- Nicholas P. Boyer
- Neurobiology Curriculum, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Stephanie L. Gupton
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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21
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Sun D, Sun XD, Zhao L, Lee DH, Hu JX, Tang FL, Pan JX, Mei L, Zhu XJ, Xiong WC. Neogenin, a regulator of adult hippocampal neurogenesis, prevents depressive-like behavior. Cell Death Dis 2018; 9:8. [PMID: 29311593 PMCID: PMC5849041 DOI: 10.1038/s41419-017-0019-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/19/2017] [Accepted: 10/02/2017] [Indexed: 11/09/2022]
Abstract
Adult neurogenesis in hippocampal dentate gyrus (DG) is a complex, but precisely controlled process. Dysregulation of this event contributes to multiple neurological disorders, including major depression. Thus, it is of considerable interest to investigate how adult hippocampal neurogenesis is regulated. Here, we present evidence for neogenin, a multifunctional transmembrane receptor, to regulate adult mouse hippocampal neurogenesis. Loss of neogenin in adult neural stem cells (NSCs) or neural progenitor cells (NPCs) impaired NSCs/NPCs proliferation and neurogenesis, whereas increased their astrocytic differentiation. Mechanistic studies revealed a role for neogenin to positively regulate Gli1, a crucial downstream transcriptional factor of sonic hedgehog, and expression of Gli1 into neogenin depleted NSCs/NPCs restores their proliferation. Further morphological and functional studies showed additional abnormities, including reduced dendritic branches and spines, and impaired glutamatergic neuro-transmission, in neogenin-depleted new-born DG neurons; and mice with depletion of neogenin in NSCs/NPCs exhibited depressive-like behavior. These results thus demonstrate unrecognized functions of neogenin in adult hippocampal NSCs/NPCs-promoting NSCs/NPCs proliferation and neurogenesis and preventing astrogliogenesis and depressive-like behavior, and suggest neogenin regulation of Gli1 signaling as a possible underlying mechanism.
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Affiliation(s)
- Dong Sun
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Institute of Cytology and Genetics, Northeast Normal University, Changchun, Jilin, 130024, China.,Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Xiang-Dong Sun
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Lu Zhao
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Institute of Cytology and Genetics, Northeast Normal University, Changchun, Jilin, 130024, China.,Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Dae-Hoon Lee
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Jin-Xia Hu
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA.,Department of Neurology, The affiliated hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, 221002, China
| | - Fu-Lei Tang
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Jin-Xiu Pan
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Lin Mei
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA
| | - Xiao-Juan Zhu
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Institute of Cytology and Genetics, Northeast Normal University, Changchun, Jilin, 130024, China.
| | - Wen-Cheng Xiong
- Department of Neuroscience & Regenerative Medicine and Department of Neurology, Augusta University, Augusta, GA, 30912, USA.
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Gómez C, Jimeno D, Fernández-Medarde A, García-Navas R, Calzada N, Santos E. Ras-GRF2 regulates nestin-positive stem cell density and onset of differentiation during adult neurogenesis in the mouse dentate gyrus. Mol Cell Neurosci 2017; 85:127-147. [PMID: 28966131 DOI: 10.1016/j.mcn.2017.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/11/2017] [Accepted: 09/17/2017] [Indexed: 12/12/2022] Open
Abstract
Various parameters of neurogenesis were analyzed in parallel in the two neurogenic areas (the Dentate Gyrus[DG] and the Subventricular Zone[SVZ]/Rostral Migratory Stream[RMS]/Main Olfactory Bulb[MOB] neurogenic system) of adult WT and KO mouse strains for the Ras-GRF1/2 genes (Ras-GRF1-KO, Ras-GRF2-KO, Ras-GRF1/2-DKO). Significantly reduced numbers of doublecortin[DCX]-positive cells were specifically observed in the DG, but not the SVZ/RMS/MOB neurogenic region, of Ras-GRF2-KO and Ras-GRF1/2-DKO mice indicating that this novel Ras-GRF2-dependent phenotype is spatially restricted to a specific neurogenic area. Consistent with a role of CREB as mediator of Ras-GRF2 function in neurogenesis, the density of p-CREB-positive cells was also specifically reduced in all neurogenic regions of Ras-GRF2-KO and DKO mice. Similar levels of early neurogenic proliferation markers (Ki67, BrdU) were observed in all different Ras-GRF genotypes analyzed but significantly elevated levels of nestin-immunolabel, particularly of undifferentiated, highly ramified, A-type nestin-positive neurons were specifically detected in the DG but not the SVZ/RMS/MOB of Ras-GRF2-KO and DKO mice. Together with assays of other neurogenic markers (GFAP, Sox2, Tuj1, NeuN), these observations suggest that the deficit of DCX/p-CREB-positive cells in the DG of Ras-GRF2-depleted mice does not involve impaired neuronal proliferation but rather delayed transition from the stem cell stage to the differentiation stages of the neurogenic process. This model is also supported by functional analyses of DG-derived neurosphere cultures and transcriptional characterization of the neurogenic areas of mice of all relevant Ras-GRF genotypes suggesting that the neurogenic role of Ras-GRF2 is exerted in a cell-autonomous manner through a specific transcriptional program.
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Affiliation(s)
- Carmela Gómez
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - David Jimeno
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - Alberto Fernández-Medarde
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - Rósula García-Navas
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - Nuria Calzada
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - Eugenio Santos
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain.
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23
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Kam JWK, Dumontier E, Baim C, Brignall AC, Mendes da Silva D, Cowan M, Kennedy TE, Cloutier JF. RGMB and neogenin control cell differentiation in the developing olfactory epithelium. Development 2017; 143:1534-46. [PMID: 27143755 DOI: 10.1242/dev.118638] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 02/29/2016] [Indexed: 12/25/2022]
Abstract
Cellular interactions are key for the differentiation of distinct cell types within developing epithelia, yet the molecular mechanisms engaged in these interactions remain poorly understood. In the developing olfactory epithelium (OE), neural stem/progenitor cells give rise to odorant-detecting olfactory receptor neurons (ORNs) and glial-like sustentacular (SUS) cells. Here, we show in mice that the transmembrane receptor neogenin (NEO1) and its membrane-bound ligand RGMB control the balance of neurons and glial cells produced in the OE. In this layered epithelium, neogenin is expressed in progenitor cells, while RGMB is restricted to adjacent newly born ORNs. Ablation of Rgmb via gene-targeting increases the number of dividing progenitor cells in the OE and leads to supernumerary SUS cells. Neogenin loss-of-function phenocopies these effects observed in Rgmb(-/-) mice, supporting the proposal that RGMB-neogenin signaling regulates progenitor cell numbers and SUS cell production. Interestingly, Neo1(-/-) mice also exhibit increased apoptosis of ORNs, implicating additional ligands in the neogenin-dependent survival of ORNs. Thus, our results indicate that RGMB-neogenin-mediated cell-cell interactions between newly born neurons and progenitor cells control the ratio of glia and neurons produced in the OE.
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Affiliation(s)
- Joseph Wai Keung Kam
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - Emilie Dumontier
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - Christopher Baim
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - Alexandra C Brignall
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - David Mendes da Silva
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Center for Neuroscience and Cell Biology and Department of Life Sciences, University of Coimbra, Rua Larga, Coimbra 3004-517, Portugal
| | - Mitra Cowan
- Centre de Recherches du Centre Hospitalier de l'Université de Montréal, 900 rue Saint-Denis, Montréal, Canada H2X 0A9
| | - Timothy E Kennedy
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Anatomy and Cell Biology, McGill University, 3640 University, Montréal, Québec, Canada H3A 0C7
| | - Jean-François Cloutier
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Anatomy and Cell Biology, McGill University, 3640 University, Montréal, Québec, Canada H3A 0C7
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24
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Hong N, Kim MH, Min CK, Kim HJ, Lee JH. The co-expression of Neogenin with SOX2 in hippocampal neurons. Biochem Biophys Res Commun 2017. [DOI: 10.1016/j.bbrc.2017.06.062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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25
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Zhang X, Xu L, Tian H, Wang C, Wang W, Ru S. Monocrotophos, an organophosphorus insecticide, disrupts the expression of HpNetrin and its receptor neogenin during early development in the sea urchin (Hemicentrotus pulcherrimus). Neurotoxicology 2017. [PMID: 28645554 DOI: 10.1016/j.neuro.2017.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Netrins, chemotropic guidance cues, can guide the extension of serotonergic axons by binding to netrin receptors during neural development. However, little is known about whether disruption of netrin signaling is involved in the mechanisms by which organophosphorus pesticides affect serotonergic nervous system (SNS) development. In this study, we evaluated the effects of the pesticide monocrotophos (MCP) on the expression patterns of HpNetrin and its receptor neogenin as well as on the intracellular calcium ion (Ca2+) levels in Hemicentrotus pulcherrimus (sea urchin) by exposing fertilized embryos to 0, 0.01, 0.10, and 1.00mg/L MCP. The results showed that MCP disrupted HpNetrin and neogenin expression at different developmental stages in H. pulcherrimus and that Ca2+ appeared to be involved in the MCP-induced developmental neurotoxicity. Specifically, the lower concentrations of MCP elevated HpNetrin and neogenin transcription, resulting in higher intracellular Ca2+ levels during the early developmental stages in the sea urchin; this may affect netrin-directed cell migration/axon extension and subsequently disrupt serotonergic axon branching and synapse formation. In contrast, 1.00mg/L MCP exhibited an inhibitory effect on HpNetrin and neogenin transcription. This finding implies that the regulatory roles of these factors may be diminished during early development, thereby causing developmental defects in the sea urchin. Collectively, our results provide a basis for exploring the involvement of netrin and neogenin in the organophosphate-induced disruption of the SNS during development.
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Affiliation(s)
- Xiaona Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Lei Xu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Hua Tian
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Cuicui Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Wei Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Shaoguo Ru
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
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26
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Siebold C, Yamashita T, Monnier PP, Mueller BK, Pasterkamp RJ. RGMs: Structural Insights, Molecular Regulation, and Downstream Signaling. Trends Cell Biol 2017; 27:365-378. [PMID: 28007423 PMCID: PMC5404723 DOI: 10.1016/j.tcb.2016.11.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 11/27/2016] [Accepted: 11/28/2016] [Indexed: 12/20/2022]
Abstract
Although originally discovered as neuronal growth cone-collapsing factors, repulsive guidance molecules (RGMs) are now known as key players in many fundamental processes, such as cell migration, differentiation, iron homeostasis, and apoptosis, during the development and homeostasis of many tissues and organs, including the nervous, skeletal, and immune systems. Furthermore, three RGMs (RGMa, RGMb/DRAGON, and RGMc/hemojuvelin) have been linked to the pathogenesis of various disorders ranging from multiple sclerosis (MS) to cancer and juvenile hemochromatosis (JHH). While the molecular details of these (patho)biological effects and signaling modes have long remained unknown, recent studies unveil several exciting and novel aspects of RGM processing, ligand-receptor interactions, and downstream signaling. In this review, we highlight recent advances in the mechanisms-of-action and function of RGM proteins.
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Affiliation(s)
- Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Philippe P Monnier
- Krembil Research Institute, 60 Leonard Street, M5T 2S8, Toronto, ONT, Canada
| | - Bernhard K Mueller
- Neuroscience Discovery Research, Abbvie, Knollstrasse 50, 67061 Ludwigshafen, Germany
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
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27
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Mirakaj V, Rosenberger P. Immunomodulatory Functions of Neuronal Guidance Proteins. Trends Immunol 2017; 38:444-456. [PMID: 28438491 DOI: 10.1016/j.it.2017.03.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 03/28/2017] [Accepted: 03/30/2017] [Indexed: 02/07/2023]
Abstract
Neuronal guidance proteins (NGPs) were originally identified for their role during the embryonic development of the nervous system. Recent years have seen the discovery of NGP functions during immune responses. In this context, NGPs were demonstrated to control leukocyte migration and the release of cytokines during conditions of acute inflammation, such as lung injury or sepsis. However, NGPs also display potent actions in the resolution of inflammation, chronic inflammatory conditions, the development of atherosclerosis, and during ischemia followed by reperfusion. Here, we provide an overview of the current state of knowledge about the role of NGPs in the immune system and describe their immunomodulatory function.
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Affiliation(s)
- Valbona Mirakaj
- Department of Anesthesia and Intensive Care Medicine, Tübingen University Hospital, Faculty of Medicine, Eberhard-Karls University Tübingen, Hoppe-Seyler-Straße 3, 72076 Tübingen, Germany.
| | - Peter Rosenberger
- Department of Anesthesia and Intensive Care Medicine, Tübingen University Hospital, Faculty of Medicine, Eberhard-Karls University Tübingen, Hoppe-Seyler-Straße 3, 72076 Tübingen, Germany.
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28
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Fujita Y, Yamashita T. The roles of RGMa-neogenin signaling in inflammation and angiogenesis. Inflamm Regen 2017; 37:6. [PMID: 29259705 PMCID: PMC5725648 DOI: 10.1186/s41232-017-0037-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/16/2017] [Indexed: 12/13/2022] Open
Abstract
Repulsive guidance molecule (RGM) is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein that has diverse functions in the developing and pathological central nervous system (CNS). The binding of RGM to its receptor neogenin regulates axon guidance, neuronal differentiation, and survival during the development of the CNS. In the pathological state, RGM expression is induced after spinal cord injury, and the inhibition of RGM promotes axon growth and functional recovery. Furthermore, RGM expression is also observed in immune cells, and RGM regulates inflammation and neurodegeneration in autoimmune encephalomyelitis. RGMa induces T cell activation in experimental autoimmune encephalomyelitis (EAE), which is the animal model of multiple sclerosis (MS). RGM is expressed in pathogenic Th17 cells and induces neurodegeneration by binding to neogenin. Angiogenesis is an additional key factor involved in the pathophysiology of EAE. Via neogenin, treatment with RGMa can suppress endothelial tube formation; this finding indicates that RGMa inhibits neovascularization. These observations suggest the feasibility of utilizing the RGMa-neogenin signaling pathway as a therapeutic target to overcome inflammation and neurodegeneration. This review focuses on the molecular mechanisms of inflammation and angiogenesis via RGM-neogenin signaling.
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Affiliation(s)
- Yuki Fujita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, Japan
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29
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de Ramon Francàs G, Zuñiga NR, Stoeckli ET. The spinal cord shows the way - How axons navigate intermediate targets. Dev Biol 2016; 432:43-52. [PMID: 27965053 DOI: 10.1016/j.ydbio.2016.12.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/26/2016] [Accepted: 12/01/2016] [Indexed: 12/13/2022]
Abstract
Functional neural circuits depend on the establishment of specific connections between neurons and their target cells. To this end, many axons have to travel long distances to reach their target cells during development. Studies addressing the molecular mechanisms of axon guidance have to overcome the complexity of subpopulation-specific requirements with respect to pathways, guidance cues, and target recognition. Compared to the brain, the relatively simple structure of the spinal cord provides an advantage for experimental studies of axon guidance mechanisms. Therefore, the so far best understood model for axon guidance is the dI1 population of dorsal interneurons of the spinal cord. They extend their axons ventrally towards the floor plate. After midline crossing, they turn rostrally along the contralateral floor-plate border. Despite the fact that the trajectory of dI1 axons seems to be rather simple, the number of axon guidance molecules involved in the decisions taken by these axons is bewildering. Because guidance molecules and mechanisms are conserved throughout the developing nervous system, we can generalize what we have learned about the navigation of the floor plate as an intermediate target for commissural axons to the brain.
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Affiliation(s)
- Gemma de Ramon Francàs
- University of Zurich, Department of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Nikole R Zuñiga
- University of Zurich, Department of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Esther T Stoeckli
- University of Zurich, Department of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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30
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Abstract
Axon guidance relies on a combinatorial code of receptor and ligand interactions that direct adhesive/attractive and repulsive cellular responses. Recent structural data have revealed many of the molecular mechanisms that govern these interactions and enabled the design of sophisticated mutant tools to dissect their biological functions. Here, we discuss the structure/function relationships of four major classes of guidance cues (ephrins, semaphorins, slits, netrins) and examples of morphogens (Wnt, Shh) and of cell adhesion molecules (FLRT). These cell signaling systems rely on specific modes of receptor-ligand binding that are determined by selective binding sites; however, defined structure-encoded receptor promiscuity also enables cross talk between different receptor/ligand families and can also involve extracellular matrix components. A picture emerges in which a multitude of highly context-dependent structural assemblies determines the finely tuned cellular behavior required for nervous system development.
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Affiliation(s)
- Elena Seiradake
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, United Kingdom;
| | - E Yvonne Jones
- Wellcome Trust Centre for Human Genetics, Oxford University, Oxford OX3 7BN, United Kingdom;
| | - Rüdiger Klein
- Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany;
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
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31
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Lee NK, Fok KW, White A, Wilson NH, O'Leary CJ, Cox HL, Michael M, Yap AS, Cooper HM. Neogenin recruitment of the WAVE regulatory complex maintains adherens junction stability and tension. Nat Commun 2016; 7:11082. [PMID: 27029596 PMCID: PMC4821876 DOI: 10.1038/ncomms11082] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/19/2016] [Indexed: 02/06/2023] Open
Abstract
To maintain tissue integrity during epithelial morphogenesis, adherens junctions (AJs) must resist the mechanical stresses exerted by dynamic tissue movements. Junctional stability is dependent on actomyosin contractility within the actin ring. Here we describe a novel function for the axon guidance receptor, Neogenin, as a key component of the actin nucleation machinery governing junctional stability. Loss of Neogenin perturbs AJs and attenuates junctional tension. Neogenin promotes actin nucleation at AJs by recruiting the Wave regulatory complex (WRC) and Arp2/3. A direct interaction between the Neogenin WIRS domain and the WRC is crucial for the spatially restricted recruitment of the WRC to the junction. Thus, we provide the first example of a functional WIRS–WRC interaction in epithelia. We further show that Neogenin regulates cadherin recycling at the AJ. In summary, we identify Neogenin as a pivotal component of the AJ, where it influences both cadherin dynamics and junctional tension. The stability of epithelial adherens junctions depends on tension generated by actomyosin contractility. Here Lee et al. describe a novel role for the axon guidance receptor Neogenin in maintaining junctional stability by recruiting actin nucleation machinery to adherens junctions.
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Affiliation(s)
- Natalie K Lee
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ka Wai Fok
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Amanda White
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nicole H Wilson
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Conor J O'Leary
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Hayley L Cox
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Magdalene Michael
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Alpha S Yap
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Helen M Cooper
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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Unmasking a novel disease gene NEO1 associated with autism spectrum disorders by a hemizygous deletion on chromosome 15 and a functional polymorphism. Behav Brain Res 2016; 300:135-42. [DOI: 10.1016/j.bbr.2015.10.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 10/14/2015] [Accepted: 10/21/2015] [Indexed: 11/20/2022]
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Satoh J, Tabunoki H, Ishida T, Saito Y, Arima K. Accumulation of a repulsive axonal guidance molecule RGMa in amyloid plaques: a possible hallmark of regenerative failure in Alzheimer's disease brains. Neuropathol Appl Neurobiol 2015; 39:109-20. [PMID: 22582881 DOI: 10.1111/j.1365-2990.2012.01281.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
AIMS RGMa is a repulsive guidance molecule that induces the collapse of axonal growth cones by interacting with the receptor neogenin in the central nervous system during development. It remains unknown whether RGMa plays a role in the neurodegenerative process of Alzheimer's disease (AD). We hypothesize that RGMa, if it is concentrated on amyloid plaques, might contribute to a regenerative failure of degenerating axons in AD brains. METHODS By immunohistochemistry, we studied RGMa and neogenin (NEO1) expression in the frontal cortex and the hippocampus of 6 AD and 12 control cases. The levels of RGMa expression were determined by qRT-PCR and Western blot in cultured human astrocytes following exposure to cytokines and amyloid beta (Aβ) peptides. RESULTS In AD brains, an intense RGMa immunoreactivity was identified on amyloid plaques and in the glial scar. In the control brains, the glial scar and vascular foot processes of astrocytes expressed RGMa immunoreactivity, while oligodendrocytes and microglia were negative for RGMa. In AD brains, a small subset of amyloid plaques expressed a weak NEO1 immunoreactivity, while some reactive astrocytes in both AD and control brains showed an intense NEO1 immunoreactivity. In human astrocytes, transforming growth factor beta-1 (TGFβ1 ), Aβ 1-40 or Aβ 1-42 markedly elevated the levels of RGMa, and TGFβ1 also increased its own levels. Coimmunoprecipitation analysis validated the molecular interaction between RGMa and the C-terminal fragment β of amyloid beta precursor protein (APP). Furthermore, recombinant RGMa protein interacted with amyloid plaques in situ. CONCLUSIONS RGMa, produced by TGFβ-activated astrocytes and accumulated in amyloid plaques and the glial scar, could contribute to the regenerative failure of degenerating axons in AD brains.
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Affiliation(s)
- J Satoh
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Departments ofLaboratory MedicinePsychiatry, National Center Hospital, NCNP, TokyoDepartment of Pathology and Laboratory Medicine, Kohnodai Hospital, NCGM, Chiba, Japan
| | - H Tabunoki
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Departments ofLaboratory MedicinePsychiatry, National Center Hospital, NCNP, TokyoDepartment of Pathology and Laboratory Medicine, Kohnodai Hospital, NCGM, Chiba, Japan
| | - T Ishida
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Departments ofLaboratory MedicinePsychiatry, National Center Hospital, NCNP, TokyoDepartment of Pathology and Laboratory Medicine, Kohnodai Hospital, NCGM, Chiba, Japan
| | - Y Saito
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Departments ofLaboratory MedicinePsychiatry, National Center Hospital, NCNP, TokyoDepartment of Pathology and Laboratory Medicine, Kohnodai Hospital, NCGM, Chiba, Japan
| | - K Arima
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Departments ofLaboratory MedicinePsychiatry, National Center Hospital, NCNP, TokyoDepartment of Pathology and Laboratory Medicine, Kohnodai Hospital, NCGM, Chiba, Japan
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34
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Zhang Q, Liang F, Ke Y, Huo Y, Li M, Li Y, Yue J. Overexpression of neogenin inhibits cell proliferation and induces apoptosis in human MDA-MB-231 breast carcinoma cells. Oncol Rep 2015; 34:258-64. [PMID: 25998984 DOI: 10.3892/or.2015.4004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/13/2015] [Indexed: 11/05/2022] Open
Abstract
Neogenin has been documented as playing an important role in cancer development. Although an elevated expression of neogenin has been detected in human breast cancer, the role of neogenin in breast cancer cells is not clearly understood. In the present study, we investigated neogenin in breast cancer cell proliferation, migration and apoptosis. We found that neogenin overexpression markedly reduced the proliferation and migration of breast cancer cells (P<0.05). Neogenin overexpression resulted in a reduction in the apoptosis rate. Inhibition of neogenin expression by neogenin siRNA dramatically promoted the proliferation and migration of breast cancer cells, whereas it inhibited cell apoptosis. Furthermore, we found that BMP-2-induced phosphorylation of Smad1/5/8 which was inhibited by neogenin overexpression. The present study demonstrates that neogenin may be a tumor suppressor in breast cancer. Neogenin may serve as a potential diagnostic marker and therapeutic target for breast cancer.
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Affiliation(s)
- Qingsong Zhang
- Department of Breast Surgery, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
| | - Fang Liang
- Department of Oncology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
| | - Yang Ke
- Department of Oncology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
| | - Yanping Huo
- Department of Breast Surgery, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
| | - Mingchuang Li
- Department of Breast Surgery, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
| | - Yanyan Li
- Department of Oncology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
| | - Junmin Yue
- Department of Urology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan 450007, P.R. China
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35
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Kim SJ, Wang YG, Lee HW, Kang HG, La SH, Choi IJ, Irimura T, Ro JY, Bresalier RS, Chun KH. Up-regulation of neogenin-1 increases cell proliferation and motility in gastric cancer. Oncotarget 2015; 5:3386-98. [PMID: 24930499 PMCID: PMC4102817 DOI: 10.18632/oncotarget.1960] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Although elevated expression of neogenin-1 has been detected in human gastric cancer tissue, its role in gastric tumorigenesis remains unclear due to the lack of neogenin-1 studies in cancer. Therefore, we demonstrated here the function and regulatory mechanism of neogenin-1 in gastric cancer. Neogenin-1 ablation decreased proliferation and migration of gastric cancer cells, whereas its over-expression reversed these effects. Xenografted analyses using gastric cancer cells displayed statistically significant inhibition of tumor growth by neogenin-1 depletion. Interestingly, galectin-3 interacted with HSF-1 directly, which facilitated nuclear-localization and binding on neogenin-1 promoter to drive its transcription and gastric cancer cell motility. The galectin-3-increased gastric cancer cell motility was down-regulated by HSF-1 depletion. Moreover, the parallel expression patterns of galectin-3 and neogenin-1, as well as those of HSF-1 and neogenin-1, were detected in the malignant tissues of gastric cancer patients. Taken together, high-expression of neogenin-1 promotes gastric cancer proliferation and motility and its expression is regulated by HSF-1 and galectin-3 interaction. In addition, we propose further studies for neogenin-1 and its associated pathways to provide them as a proper target for gastric cancer therapy.
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Affiliation(s)
- Seok-Jun Kim
- Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, Seoul, Republic of Korea
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36
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O'Leary CJ, Bradford D, Chen M, White A, Blackmore DG, Cooper HM. The Netrin/RGM Receptor, Neogenin, Controls Adult Neurogenesis by Promoting Neuroblast Migration and Cell Cycle Exit. Stem Cells 2015; 33:503-14. [DOI: 10.1002/stem.1861] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 07/31/2014] [Accepted: 09/06/2014] [Indexed: 01/16/2023]
Affiliation(s)
- Conor J. O'Leary
- The University of Queensland, Queensland Brain Institute; Brisbane Queensland Australia
| | - DanaKai Bradford
- The University of Queensland, Queensland Brain Institute; Brisbane Queensland Australia
| | - Min Chen
- The University of Queensland, Queensland Brain Institute; Brisbane Queensland Australia
| | - Amanda White
- The University of Queensland, Queensland Brain Institute; Brisbane Queensland Australia
| | - Daniel G. Blackmore
- The University of Queensland, Queensland Brain Institute; Brisbane Queensland Australia
| | - Helen M. Cooper
- The University of Queensland, Queensland Brain Institute; Brisbane Queensland Australia
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37
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Abstract
Neuronal cell death happens as a result of the normal physiological process that occurs during development, or as part of the pathological process that occurs during disease. Death-associated protein kinase (DAPK) is an intracellular protein that mediates cell death by its serine/threonine kinase activity, and transmits apoptotic cell death signals in various cells, including neurons. DAPK is elevated in injured neurons in acute models of injury such as ischemia and seizure. The absence of DAPK has been shown to protect neurons from a wide variety of acute toxic insults. Moreover, DAPK also regulates neuronal cell death during central nervous system development. Neurons are initially overproduced in the developing nervous system, following which approximately one-half of the original cell population dies. This "naturally-occurring" or "programmed" cell death is essential for the construction of the developing nervous system. In this review, we focus on the role of DAPK in neuronal cell death after neuronal injury. The participation of DAPK in developmental neuronal death is also explained.
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Affiliation(s)
- Yuki Fujita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan
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38
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Finci LI, Krüger N, Sun X, Zhang J, Chegkazi M, Wu Y, Schenk G, Mertens HDT, Svergun DI, Zhang Y, Wang JH, Meijers R. The crystal structure of netrin-1 in complex with DCC reveals the bifunctionality of netrin-1 as a guidance cue. Neuron 2014; 83:839-849. [PMID: 25123307 DOI: 10.1016/j.neuron.2014.07.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2014] [Indexed: 01/01/2023]
Abstract
Netrin-1 is a guidance cue that can trigger either attraction or repulsion effects on migrating axons of neurons, depending on the repertoire of receptors available on the growth cone. How a single chemotropic molecule can act in such contradictory ways has long been a puzzle at the molecular level. Here we present the crystal structure of netrin-1 in complex with the Deleted in Colorectal Cancer (DCC) receptor. We show that one netrin-1 molecule can simultaneously bind to two DCC molecules through a DCC-specific site and through a unique generic receptor binding site, where sulfate ions staple together positively charged patches on both DCC and netrin-1. Furthermore, we demonstrate that UNC5A can replace DCC on the generic receptor binding site to switch the response from attraction to repulsion. We propose that the modularity of binding allows for the association of other netrin receptors at the generic binding site, eliciting alternative turning responses.
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Affiliation(s)
- Lorenzo I Finci
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, China.,Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA. 02215, USA
| | - Nina Krüger
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607, Hamburg, Germany
| | - Xiaqin Sun
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Jie Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Magda Chegkazi
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607, Hamburg, Germany
| | - Yu Wu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Gundolf Schenk
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607, Hamburg, Germany
| | - Haydyn D T Mertens
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607, Hamburg, Germany
| | - Dmitri I Svergun
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607, Hamburg, Germany
| | - Yan Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, China.,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Jia-Huai Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, 100871, China.,Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA. 02215, USA
| | - Rob Meijers
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607, Hamburg, Germany
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39
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Xu K, Wu Z, Renier N, Antipenko A, Tzvetkova-Robev D, Xu Y, Minchenko M, Nardi-Dei V, Rajashankar KR, Himanen J, Tessier-Lavigne M, Nikolov DB. Neural migration. Structures of netrin-1 bound to two receptors provide insight into its axon guidance mechanism. Science 2014; 344:1275-9. [PMID: 24876346 PMCID: PMC4369087 DOI: 10.1126/science.1255149] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Netrins are secreted proteins that regulate axon guidance and neuronal migration. Deleted in colorectal cancer (DCC) is a well-established netrin-1 receptor mediating attractive responses. We provide evidence that its close relative neogenin is also a functional netrin-1 receptor that acts with DCC to mediate guidance in vivo. We determined the structures of a functional netrin-1 region, alone and in complexes with neogenin or DCC. Netrin-1 has a rigid elongated structure containing two receptor-binding sites at opposite ends through which it brings together receptor molecules. The ligand/receptor complexes reveal two distinct architectures: a 2:2 heterotetramer and a continuous ligand/receptor assembly. The differences result from different lengths of the linker connecting receptor domains fibronectin type III domain 4 (FN4) and FN5, which differs among DCC and neogenin splice variants, providing a basis for diverse signaling outcomes.
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Affiliation(s)
- Kai Xu
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Zhuhao Wu
- Laboratory of Brain Development and Repair, The Rockefeller University, New York, New York 10065
| | - Nicolas Renier
- Laboratory of Brain Development and Repair, The Rockefeller University, New York, New York 10065
| | - Alexander Antipenko
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | | | - Yan Xu
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Maria Minchenko
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Vincenzo Nardi-Dei
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Kanagalaghatta R. Rajashankar
- Department of Chemistry and Chemical Biology, Cornell University & NE-CAT, Advanced Photon Source, Argonne, IL 60439
| | - Juha Himanen
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Marc Tessier-Lavigne
- Laboratory of Brain Development and Repair, The Rockefeller University, New York, New York 10065,Correspondence to: or
| | - Dimitar B. Nikolov
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065,Correspondence to: or
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40
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O'Leary C, Cole SJ, Langford M, Hewage J, White A, Cooper HM. RGMa regulates cortical interneuron migration and differentiation. PLoS One 2013; 8:e81711. [PMID: 24312340 PMCID: PMC3842424 DOI: 10.1371/journal.pone.0081711] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 10/23/2013] [Indexed: 11/24/2022] Open
Abstract
The etiology of neuropsychiatric disorders, including schizophrenia and autism, has been linked to a failure to establish the intricate neural network comprising excitatory pyramidal and inhibitory interneurons during neocortex development. A large proportion of cortical inhibitory interneurons originate in the medial ganglionic eminence (MGE) of the ventral telencephalon and then migrate through the ventral subventricular zone, across the corticostriatal junction, into the embryonic cortex. Successful navigation of newborn interneurons through the complex environment of the ventral telencephalon is governed by spatiotemporally restricted deployment of both chemorepulsive and chemoattractive guidance cues which work in concert to create a migratory corridor. Despite the expanding list of interneuron guidance cues, cues responsible for preventing interneurons from re-entering the ventricular zone of the ganglionic eminences have not been well characterized. Here we provide evidence that the chemorepulsive axon guidance cue, RGMa (Repulsive Guidance Molecule a), may fulfill this function. The ventricular zone restricted expression of RGMa in the ganglionic eminences and the presence of its receptor, Neogenin, in the ventricular zone and on newborn and maturing MGE-derived interneurons implicates RGMa-Neogenin interactions in interneuron differentiation and migration. Using an in vitro approach, we show that RGMa promotes interneuron differentiation by potentiating neurite outgrowth. In addition, using in vitro explant and migration assays, we provide evidence that RGMa is a repulsive guidance cue for newborn interneurons migrating out of the ganglionic eminence ventricular zone. Intriguingly, the alternative Neogenin ligand, Netrin-1, had no effect on migration. However, we observed complete abrogation of RGMa-induced chemorepulsion when newborn interneurons were simultaneously exposed to RGMa and Netrin-1 gradients, suggesting a novel mechanism for the tight regulation of RGMa-guided interneuron migration. We propose that during peak neurogenesis, repulsive RGMa-Neogenin interactions drive interneurons into the migratory corridor and prevent re-entry into the ventricular zone of the ganglionic eminences.
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Affiliation(s)
- Conor O'Leary
- The University of Queensland, Queensland Brain Institute, Brisbane, Queensland, Australia
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41
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Brugeaud A, Tong M, Luo L, Edge ASB. Inhibition of repulsive guidance molecule, RGMa, increases afferent synapse formation with auditory hair cells. Dev Neurobiol 2013; 74:457-66. [PMID: 24123853 DOI: 10.1002/dneu.22136] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/03/2013] [Accepted: 09/23/2013] [Indexed: 11/12/2022]
Abstract
The peripheral fibers that extend from auditory neurons to hair cells are sensitive to damage, and replacement of the fibers and their afferent synapse with hair cells would be of therapeutic interest. Here, we show that RGMa, a repulsive guidance molecule previously shown to play a role in the development of the chick visual system, is expressed in the developing, newborn, and mature mouse inner ear. The effect of RGMa on synaptogenesis between afferent neurons and hair cells, from which afferent connections had been removed, was assessed. Contact of neural processes with hair cells and elaboration of postsynaptic densities at sites of the ribbon synapse were increased by treatment with a blocking antibody to RGMa, and pruning of auditory fibers to achieve the mature branching pattern of afferent neurons was accelerated. Inhibition by RGMa could thus explain why auditory neurons have a low capacity to regenerate peripheral processes: postnatal spiral ganglion neurons retain the capacity to send out processes that respond to signals for synapse formation, but expression of RGMa postnatally appears to be detrimental to regeneration of afferent hair cell innervation and antagonizes synaptogenesis. Increased synaptogenesis after inhibition of RGMa suggests that manipulation of guidance or inhibitory factors may provide a route to increase formation of new synapses at deafferented hair cells.
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Affiliation(s)
- Aurore Brugeaud
- Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, 02115; Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 02114
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42
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Wilson NH, Stoeckli ET. Sonic hedgehog regulates its own receptor on postcrossing commissural axons in a glypican1-dependent manner. Neuron 2013; 79:478-91. [PMID: 23931997 DOI: 10.1016/j.neuron.2013.05.025] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2013] [Indexed: 11/28/2022]
Abstract
Upon reaching their intermediate target, the floorplate, commissural axons acquire responsiveness to repulsive guidance cues, allowing the axons to exit the midline and adopt a contralateral, longitudinal trajectory. The molecular mechanisms that regulate this switch from attraction to repulsion remain poorly defined. Here, we show that the heparan sulfate proteoglycan Glypican1 (GPC1) is required as a coreceptor for the Shh-dependent induction of Hedgehog-interacting protein (Hhip) in commissural neurons. In turn, Hhip is required for postcrossing axons to respond to a repulsive anteroposterior Shh gradient. Thus, Shh is a cue with dual function. In precrossing axons it acts as an attractive guidance molecule in a transcription-independent manner. At the same time, Shh binds to GPC1 to induce the expression of its own receptor, Hhip, which mediates the repulsive response of postcrossing axons to Shh. Our study characterizes a molecular mechanism by which navigating axons switch their responsiveness at intermediate targets.
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Affiliation(s)
- Nicole H Wilson
- Institute of Molecular Life Sciences, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
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43
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Tian C, Shi H, Xiong S, Hu F, Xiong WC, Liu J. The neogenin/DCC homolog UNC-40 promotes BMP signaling via the RGM protein DRAG-1 in C. elegans. Development 2013; 140:4070-80. [PMID: 24004951 DOI: 10.1242/dev.099838] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The deleted in colorectal cancer (DCC) homolog neogenin functions in both netrin- and repulsive guidance molecule (RGM)-mediated axon guidance and in bone morphogenetic protein (BMP) signaling. How neogenin functions in mediating BMP signaling is not well understood. We show that the sole C. elegans DCC/neogenin homolog UNC-40 positively modulates a BMP-like pathway by functioning in the signal-receiving cells at the ligand/receptor level. This function of UNC-40 is independent of its role in netrin-mediated axon guidance, but requires its association with the RGM protein DRAG-1. We have identified the key residues in the extracellular domain of UNC-40 that are crucial for UNC-40-DRAG-1 interaction and UNC-40 function. Surprisingly, the extracellular domain of UNC-40 is sufficient to promote BMP signaling, in clear contrast to the requirement of its intracellular domain in mediating axon guidance. Mouse neogenin lacking the intracellular domain is also capable of mediating BMP signaling. These findings reveal an unexpected mode of action for neogenin regulation of BMP signaling.
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Affiliation(s)
- Chenxi Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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44
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Milla LA, Arros A, Espinoza N, Remke M, Kool M, Taylor MD, Pfister SM, Wainwright BJ, Palma V. Neogenin1 is a Sonic Hedgehog target in medulloblastoma and is necessary for cell cycle progression. Int J Cancer 2013; 134:21-31. [PMID: 23775842 DOI: 10.1002/ijc.28330] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/14/2013] [Indexed: 12/16/2022]
Abstract
The canonical Sonic Hedgehog (Shh)/Gli pathway plays multiples roles during central nervous system (CNS) development. To elucidate the molecular repertoire of Shh mediators, we have recently described novel transcriptional targets in response to Shh pathway modulation. Among them, we were able to identify Neogenin1 (Neo1), a death dependence receptor, as a new direct Shh downstream regulator in neural precursor proliferation. As appropriate Shh signaling is required for cerebellar growth and alterations cause Shh-driven medulloblastoma (MB), here we have addressed the role of the Shh/Neogenin1 interaction in the context of cerebellar development and cancer. We demonstrate that the Shh pathway regulates Neogenin1 expression in mouse models that recapitulate the Shh MB subtype. We show that the canonical Shh pathway directly regulates the Neo1 gene acting through an upstream sequence in its promoter both in vitro and in vivo in granule neuron precursor cells. We also identified and characterized a functional Gli-binding site in the first intron of the human NEO1 gene. Gene expression profiling of more than 300 MB shows that NEO1 is indeed upregulated in SHH tumors compared to the other MB subgroups. Finally, we provide evidence that NEO1 is necessary for cell cycle progression in a human MB cell line, because a loss of function of NEO1 arrests cells in the G2/M phase. Taken together, these results highlight Neogenin1 as a novel downstream effector of the Shh pathway in MB and a possible therapeutic target.
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Affiliation(s)
- Luis A Milla
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile; FONDAP Center for Genome Regulation, Santiago, Chile
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45
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Tian C, Liu J. Repulsive guidance molecules (RGMs) and neogenin in bone morphogenetic protein (BMP) signaling. Mol Reprod Dev 2013; 80:700-17. [PMID: 23740870 DOI: 10.1002/mrd.22199] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 05/28/2013] [Indexed: 02/06/2023]
Abstract
Bone morphogenetic proteins (BMPs) belong to the transforming growth factor-beta (TGFβ) superfamily. BMPs mediate a highly conserved signal transduction cascade through the type-I and type-II serine/threonine kinase receptors and intracellular Smad proteins, which regulate multiple developmental and homeostatic processes. Mutations in this pathway can cause various diseases in humans, such as skeletal disorders, cardiovascular diseases, and various cancers. Multiple levels of regulation, including extracellular regulation, help to ensure proper spatiotemporal control of BMP signaling in the right cellular context. The family of repulsive guidance molecules (RGMs) and the type-I transmembrane protein neogenin, a paralog of DCC (Deleted in Colorectal Cancer), have been implicated in modulating the BMP pathway. In this review, we discuss the properties and functions of RGM proteins and neogenin, focusing on their roles in the modulation of BMP signal transduction.
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Affiliation(s)
- Chenxi Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
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46
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Spatiotemporal expression of repulsive guidance molecules (RGMs) and their receptor neogenin in the mouse brain. PLoS One 2013; 8:e55828. [PMID: 23457482 PMCID: PMC3573027 DOI: 10.1371/journal.pone.0055828] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 01/02/2013] [Indexed: 02/07/2023] Open
Abstract
Neogenin has been implicated in a variety of developmental processes such as neurogenesis, neuronal differentiation, apoptosis, migration and axon guidance. Binding of repulsive guidance molecules (RGMs) to Neogenin inhibits axon outgrowth of different neuronal populations. This effect requires Neogenin to interact with co-receptors of the uncoordinated locomotion-5 (Unc5) family to activate downstream Rho signaling. Although previous studies have reported RGM, Neogenin, and/or Unc5 expression, a systematic comparison of RGM and Neogenin expression in the developing nervous system is lacking, especially at later developmental stages. Furthermore, information on RGM and Neogenin expression at the protein level is limited. To fill this void and to gain further insight into the role of RGM-Neogenin signaling during mouse neural development, we studied the expression of RGMa, RGMb, Neogenin and Unc5A-D using in situ hybridization, immunohistochemistry and RGMa section binding. Expression patterns in the primary olfactory system, cortex, hippocampus, habenula, and cerebellum were studied in more detail. Characteristic cell layer-specific expression patterns were detected for RGMa, RGMb, Neogenin and Unc5A-D. Furthermore, strong expression of RGMa, RGMb and Neogenin protein was found on several major axon tracts such as the primary olfactory projections, anterior commissure and fasciculus retroflexus. These data not only hint at a role for RGM-Neogenin signaling during the development of different neuronal systems, but also suggest that Neogenin partners with different Unc5 family members in different systems. Overall, the results presented here will serve as a framework for further dissection of the role of RGM-Neogenin signaling during neural development.
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47
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Mirza R, Kivrak BG, Erzurumlu RS. Cooperative slit and netrin signaling in contralateralization of the mouse trigeminothalamic pathway. J Comp Neurol 2013; 521:312-25. [PMID: 22806432 PMCID: PMC3491114 DOI: 10.1002/cne.23188] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 05/24/2012] [Accepted: 07/06/2012] [Indexed: 12/13/2022]
Abstract
Ascending somatosensory pathways are crossed pathways representing each side of the body in the contralateral neocortex. The principal sensory nucleus of the trigeminal nerve (PrV) relays the facial sensations to the contralateral somatosensory cortex via the ventrobasal thalamus. In the companion article (Kivrak and Erzurumlu [2012] J. Comp. Neurol. 12-0013) we described the normal development of the trigeminal lemniscal pathway in the mouse. In this study we investigated the role of midline axon navigation signals, the netrin and slit proteins. In situ hybridization assays revealed that both netrin and slit mRNAs are expressed along the midline facing the PrV axons and their receptors are expressed in developing PrV neurons. In wild-type mouse embryos, PrV axons cross the midline and take a sharp rostral turn heading toward the contralateral thalamus. Examination of trigeminal lemniscal axons in dcc knockout mice revealed absence of midline crossing between E11 and E15. However, a few axons crossed the midline at E17 and reached the contralateral thalamus, resulting in a bilateral PrV lemniscal pathway at P0. We also found that slit1, -2 or -3 single or double knockout mice have impaired development of the trigeminal-lemniscal pathway. These include axon stalling along the midline, running within the midline, and recrossing of axons back to the site of origin. Collectively, our studies indicate a cooperative role for netrin and slit proteins in midline attraction and crossing behavior of the ascending facial somatosensory projections during development.
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Affiliation(s)
- Rusella Mirza
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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48
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Robo2--slit and Dcc--netrin1 coordinate neuron axonal pathfinding within the embryonic axon tracts. J Neurosci 2012; 32:12589-602. [PMID: 22956848 DOI: 10.1523/jneurosci.6518-11.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In the embryonic vertebrate brain, early born neurons establish highly stereotyped embryonic axonal tracts along which the neuronal interconnections form. To understand the mechanism underlying neuron axonal pathfinding within the embryonic scaffold of axon tracts, we studied zebrafish anterior dorsal telencephalic (ADt) neuron development. While previous studies suggest the ADt neuronal axons extend along a commissural tract [anterior commissure (AC)] and a descending ipsilateral tract [supraoptic tract (SOT)], it is unclear whether individual ADt neuronal axons choose specific projection paths at the intersection between the AC and the SOT. We labeled individual ADt neurons using a forebrain-specific promoter to drive expression of fluorescent proteins. We found the ADt axonal projection patterns were heterogeneous and correlated with their soma positions. Our results suggest that cell intrinsic differences along the dorsal ventral axis of the telencephalon regulate the axonal projection choices. Next, we determined that the guidance receptors roundabout2 (Robo2) and deleted in colorectal cancer (Dcc) were differentially expressed in the ADt neurons. We showed that knocking down Robo2 function by injecting antisense morpholino oligonucleotides abolished the ipsilateral SOT originating from the ADt neurons. Knocking down Dcc function did not prevent formation of the AC and the SOT. In contrast, the AC was specifically reduced when Netrin1 function was knocked down. Further mechanistic studies suggested that Robo2 responded to the repellent Slit signals and suppressed the attractive Netrin signals. These findings demonstrate how Robo2-Slit and Dcc-Netrin coordinate the axonal projection choices of the developing neurons in the vertebrate forebrain.
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49
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Santiago-Medina M, Myers JP, Gomez TM. Imaging adhesion and signaling dynamics in Xenopus laevis growth cones. Dev Neurobiol 2012; 72:585-99. [PMID: 21465668 DOI: 10.1002/dneu.20886] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Xenopus laevis provides a robust model system to study cellular signaling and downstream processes during development both in vitro and in vivo. Intracellular signals must function within highly restricted spatial and temporal domains to activate specific downstream targets and cellular processes. Combining the versatility of developing Xenopus neurons with advances in fluorescent protein biosensors and imaging technologies has allowed many dynamic cellular processes to be visualized. This review will focus on the techniques we use to visualize and measure cell signaling, motility and adhesion by quantitative fluorescence microscopy in vitro and in vivo.
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Affiliation(s)
- Miguel Santiago-Medina
- Department of Neuroscience, Neuroscience Training Program, University of Wisconsin-Madison, WI 53706, USA
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50
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Jorge EC, Ahmed MU, Bothe I, Coutinho LL, Dietrich S. RGMa and RGMb expression pattern during chicken development suggest unexpected roles for these repulsive guidance molecules in notochord formation, somitogenesis, and myogenesis. Dev Dyn 2012; 241:1886-900. [PMID: 23073896 DOI: 10.1002/dvdy.23889] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 10/01/2012] [Accepted: 10/01/2012] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Repulsive guidance molecules (RGM) are high-affinity ligands for the Netrin receptor Neogenin, and they are crucial for nervous system development including neural tube closure; neuronal and neural crest cell differentiation and axon guidance. Recent studies implicated RGM molecules in bone morphogenetic protein signaling, which regulates a variety of developmental processes. Moreover, a role for RGMc in iron metabolism has been established. This suggests that RGM molecules may play important roles in non-neural tissues. RESULTS To explore which tissues and processed may be regulated by RGM molecules, we systematically investigated the expression of RGMa and RGMb, the only RGM molecules currently known for avians, in the chicken embryo. CONCLUSIONS Our study suggests so far unknown roles of RGM molecules in notochord, somite and skeletal muscle development.
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Affiliation(s)
- Erika Cristina Jorge
- Universidade Federal de Minas Gerais-Departamento de Morfologia, Belo Horizonte, MG, Brazil.
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