1
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Doan RA, Monk KR. Dock1 functions in Schwann cells to regulate development, maintenance, and repair. J Cell Biol 2025; 224:e202311041. [PMID: 40105697 PMCID: PMC11921805 DOI: 10.1083/jcb.202311041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/05/2024] [Accepted: 02/10/2025] [Indexed: 03/20/2025] Open
Abstract
Schwann cells, the myelinating glia of the peripheral nervous system (PNS), are critical for myelin development, maintenance, and repair. Rac1 is a known regulator of radial sorting, a key step in developmental myelination. Previously, in zebrafish, we showed that the loss of Dock1, a Rac1-specific guanine nucleotide exchange factor, resulted in delayed peripheral myelination during development. Here, we demonstrate that Dock1 is necessary for myelin maintenance and remyelination after injury in adult zebrafish. Furthermore, Dock1 performs an evolutionarily conserved role in mice, functioning cell autonomously in Schwann cells to regulate the development, maintenance, and repair of peripheral myelin. Pharmacological and genetic manipulation of Rac1 in larval zebrafish, along with the analysis of active Rac1 levels in developing Dock1 mutant mouse nerves, revealed an interaction between these two proteins. We propose that the interplay between Dock1 and Rac1 signaling in Schwann cells is required to establish, maintain, and facilitate repair and remyelination within the PNS.
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Affiliation(s)
- Ryan A. Doan
- The Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Kelly R. Monk
- The Vollum Institute, Oregon Health & Science University, Portland, OR, USA
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2
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Weaver MR, Shkoruta D, Pellegatta M, Berti C, Palmisano M, Ferguson S, Hurley E, French J, Patel S, Belin S, Selbach M, Paul FE, Sim F, Poitelon Y, Feltri ML. The STRIPAK complex is required for radial sorting and laminin receptor expression in Schwann cells. Cell Rep 2025; 44:115401. [PMID: 40056414 PMCID: PMC12035956 DOI: 10.1016/j.celrep.2025.115401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 01/19/2025] [Accepted: 02/14/2025] [Indexed: 03/10/2025] Open
Abstract
During peripheral nervous system development, Schwann cells undergo Rac1-dependent cytoskeletal reorganization as they insert cytoplasmic extensions into axon bundles to sort and myelinate individual axons. However, our understanding of the direct effectors targeted by Rac1 is limited. Here, we demonstrate that striatin-3 and MOB4 are Rac1 interactors. We show that Schwann-cell-specific ablation of striatin-3 causes defects in lamellipodia formation, and conditional Schwann cell knockout for striatins presents a severe delay in radial sorting. Finally, we demonstrate that deletion of Rac1 or striatin-1/3 in Schwann cells causes defects in the activation of Hippo pathway effectors YAP and TAZ and the expression of genes co-regulated by YAP and TAZ, such as extracellular matrix receptors. In summary, our results indicate that striatin-3 is a Rac1 interactor and that striatins are required for peripheral nervous system development and reveal a role for Rac1 in the regulation of the Hippo pathway in Schwann cells.
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Affiliation(s)
| | - Dominika Shkoruta
- Ivano-Frankivsk National Medical University, Ivano-Frankivsk, Ivano-Frankivsk Oblast, Ukraine
| | - Marta Pellegatta
- Institute for Myelin and Glia Exploration, Buffalo, NY, USA; Department of Biochemistry, Buffalo, NY, USA
| | - Caterina Berti
- Institute for Myelin and Glia Exploration, Buffalo, NY, USA; Department of Biochemistry, Buffalo, NY, USA
| | - Marilena Palmisano
- Institute for Myelin and Glia Exploration, Buffalo, NY, USA; Department of Biochemistry, Buffalo, NY, USA
| | - Scott Ferguson
- Institute for Myelin and Glia Exploration, Buffalo, NY, USA; Department of Pharmaceutical Sciences, Buffalo, NY, USA
| | - Edward Hurley
- Institute for Myelin and Glia Exploration, Buffalo, NY, USA
| | - Julianne French
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA
| | - Shreya Patel
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA
| | - Sophie Belin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA
| | | | | | - Fraser Sim
- Department of Pharmacology and Toxicology, Buffalo, NY, USA
| | - Yannick Poitelon
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA.
| | - M Laura Feltri
- Institute for Myelin and Glia Exploration, Buffalo, NY, USA; Department of Biochemistry, Buffalo, NY, USA; Department of Neurology, State University of New York at Buffalo Jacob's School of Medicine and Biomedical Sciences, Buffalo, NY, USA
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3
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Schumacher N, Vandenbosch R, Franzen R. Peripheral myelin: From development to maintenance. J Neurochem 2025; 169:e16268. [PMID: 39655795 DOI: 10.1111/jnc.16268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 10/24/2024] [Accepted: 10/28/2024] [Indexed: 12/18/2024]
Abstract
Peripheral myelin is synthesized by glial cells called Schwann cells (SCs). SC development and differentiation must be tightly regulated to avoid any pathological consequence affecting peripheral nerve function. Neuropathic symptoms can arise from developmental issues in SCs, as well as in adult life through processes affecting mature SCs. In this review we focus on SC differentiation from the immature towards the myelinating and non-myelinating SC stages, defining molecular mechanisms outlining radial sorting, a multi-stepped event essential for immature SC differentiation and myelination. We also describe mechanisms regulating myelin sheath maintenance and SC homeostasis during aging. Finally, we will conclude with some remaining questions in the field of SC biology.
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Affiliation(s)
- Nathalie Schumacher
- Laboratory of Nervous System Disorders and Therapies, GIGA Institute, University of Liège, Liège, Belgium
| | - Renaud Vandenbosch
- Laboratory of Developmental Neurobiology, GIGA Institute, University of Liège, Liège, Belgium
| | - Rachelle Franzen
- Laboratory of Nervous System Disorders and Therapies, GIGA Institute, University of Liège, Liège, Belgium
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4
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Weaver MR, Shkoruta D, Pellegatta M, Berti C, Palmisano M, Ferguson S, Hurley E, French J, Patel S, Belin S, Selbach M, Paul FE, Sim F, Poitelon Y, Feltri ML. The STRIPAK complex is required for radial sorting and laminin receptor expression in Schwann cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.30.620661. [PMID: 39554194 PMCID: PMC11565846 DOI: 10.1101/2024.10.30.620661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2024]
Abstract
During peripheral nervous system development, Schwann cells undergo Rac1-dependent cytoskeletal reorganization as they insert cytoplasmic extensions into axon bundles to radially sort, ensheath, and myelinate individual axons. However, our understanding of the direct effectors targeted by Rac1 is limited. Here, we demonstrate that striatin-3 and MOB4 are novel Rac1 interactors. We show that, similar to Rac1-null Schwann cells, Schwann cell specific ablation of striatin-3 causes defects in lamellipodia formation. In addition, conditional Schwann cell knockout of multiple striatin proteins presents a severe delay in radial sorting. Finally, we demonstrate here that deletion of Rac1 or striatin-1/3 in Schwann cells causes defects in Hippo pathway regulation, phosphorylation of the Hippo pathway effectors YAP and TAZ, and expression of genes co-regulated by YAP and TAZ, such as extracellular matrix receptors. In summary, our results indicate that striatin-3 is a novel Rac1 interactor, show that striatin proteins are required for peripheral nervous system development, and reveal a role for Rac1 in regulation of the Hippo pathway in Schwann cells.
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5
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Tseropoulos G, Mehrotra P, Podder AK, Wilson E, Zhang Y, Wang J, Koontz A, Gao NP, Gunawan R, Liu S, Feltri LM, Bronner ME, Andreadis ST. Immobilized NRG1 Accelerates Neural Crest like Cell Differentiation Toward Functional Schwann Cells Through Sustained Erk1/2 Activation and YAP/TAZ Nuclear Translocation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2402607. [PMID: 38952126 PMCID: PMC11633358 DOI: 10.1002/advs.202402607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Indexed: 07/03/2024]
Abstract
Neural Crest cells (NC) are a multipotent cell population that give rise to a multitude of cell types including Schwann cells (SC) in the peripheral nervous system (PNS). Immature SC interact with neuronal axons via the neuregulin 1 (NRG1) ligand present on the neuronal surface and ultimately form the myelin sheath. Multiple attempts to derive functional SC from pluripotent stem cells have met challenges with respect to expression of mature markers and axonal sorting. Here, they hypothesized that sustained signaling from immobilized NRG1 (iNRG1) might enhance the differentiation of NC derived from glabrous neonatal epidermis towards a SC phenotype. Using this strategy, NC derived SC expressed mature markers to similar levels as compared to explanted rat sciatic SC. Signaling studies revealed that sustained NRG1 signaling led to yes-associated protein 1 (YAP) activation and nuclear translocation. Furthermore, NC derived SC on iNRG1 exhibited mature SC function as they aligned with rat dorsal root ganglia (DRG) neurons in an in vitro coculture model; and most notably, aligned on neuronal axons upon implantation in a chick embryo model in vivo. Taken together their work demonstrated the importance of signaling dynamics in SC differentiation, aiming towards development of drug testing platforms for de-myelinating disorders.
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Affiliation(s)
- Georgios Tseropoulos
- Department of Chemical and Biological EngineeringUniversity at BuffaloBuffaloNY14260USA
| | - Pihu Mehrotra
- Department of Chemical and Biological EngineeringUniversity at BuffaloBuffaloNY14260USA
| | - Ashis Kumer Podder
- Department of Chemical and Biological EngineeringUniversity at BuffaloBuffaloNY14260USA
- Department of PharmacyBrac UniversityDhaka1212Bangladesh
| | - Emma Wilson
- Hunter James Kelly Research InstituteJacobs School of Medicine and Biomedical Sciences StateUniversity of New York at BuffaloBuffaloNY14203USA
- Department of BiochemistryJacobs School of Medicine and Biomedical SciencesState University of New York at BuffaloBuffaloNY14203USA
| | - Yali Zhang
- Department of Biostatistics and BioinformaticsRoswell Park Comprehensive Cancer CenterBuffaloNY14203USA
| | - Jianmin Wang
- Department of Biostatistics and BioinformaticsRoswell Park Comprehensive Cancer CenterBuffaloNY14203USA
| | - Alison Koontz
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCA91126USA
| | - Nan Papili Gao
- Department of Chemical and Biological EngineeringUniversity at BuffaloBuffaloNY14260USA
| | - Rudiyanto Gunawan
- Department of Chemical and Biological EngineeringUniversity at BuffaloBuffaloNY14260USA
- Center for CellGene and Tissue Engineering (CGTE)University at BuffaloBuffaloNY14260USA
| | - Song Liu
- Department of Biostatistics and BioinformaticsRoswell Park Comprehensive Cancer CenterBuffaloNY14203USA
| | - Laura M. Feltri
- Hunter James Kelly Research InstituteJacobs School of Medicine and Biomedical Sciences StateUniversity of New York at BuffaloBuffaloNY14203USA
- Department of BiochemistryJacobs School of Medicine and Biomedical SciencesState University of New York at BuffaloBuffaloNY14203USA
- Department of NeurologyJacobs School of Medicine and Biomedical SciencesState University of New York at BuffaloBuffaloNY14203USA
| | - Marianne E. Bronner
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCA91126USA
| | - Stelios T. Andreadis
- Department of Chemical and Biological EngineeringUniversity at BuffaloBuffaloNY14260USA
- Center for CellGene and Tissue Engineering (CGTE)University at BuffaloBuffaloNY14260USA
- Department of Biomedical EngineeringUniversity at BuffaloBuffaloNY14260USA
- Center of Excellence in Bioinformatics and Life SciencesBuffaloNY14203USA
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6
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Hu B, Moiseev D, Schena I, Faezov B, Dunbrack R, Chernoff J, Li J. PAK2 is necessary for myelination in the peripheral nervous system. Brain 2024; 147:1809-1821. [PMID: 38079473 PMCID: PMC11068108 DOI: 10.1093/brain/awad413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/03/2023] [Accepted: 11/12/2023] [Indexed: 02/12/2024] Open
Abstract
Myelination enables electrical impulses to propagate on axons at the highest speed, encoding essential life functions. The Rho family GTPases, RAC1 and CDC42, have been shown to critically regulate Schwann cell myelination. P21-activated kinase 2 (PAK2) is an effector of RAC1/CDC42, but its specific role in myelination remains undetermined. We produced a Schwann cell-specific knockout mouse of Pak2 (scPak2-/-) to evaluate PAK2's role in myelination. Deletion of Pak2, specifically in mouse Schwann cells, resulted in severe hypomyelination, slowed nerve conduction velocity and behaviour dysfunctions in the scPak2-/- peripheral nerve. Many Schwann cells in scPak2-/- sciatic nerves were arrested at the stage of axonal sorting. These abnormalities were rescued by reintroducing Pak2, but not the kinase-dead mutation of Pak2, via lentivirus delivery to scPak2-/- Schwann cells in vivo. Moreover, ablation of Pak2 in Schwann cells blocked the promyelinating effect driven by neuregulin-1, prion protein and inactivated RAC1/CDC42. Conversely, the ablation of Pak2 in neurons exhibited no phenotype. Such PAK2 activity can also be either enhanced or inhibited by different myelin lipids. We have identified a novel promyelinating factor, PAK2, that acts as a critical convergence point for multiple promyelinating signalling pathways. The promyelination by PAK2 is Schwann cell-autonomous. Myelin lipids, identified as inhibitors or activators of PAK2, may be utilized to develop therapies for repairing abnormal myelin in peripheral neuropathies.
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Affiliation(s)
- Bo Hu
- Department of Neurology, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Daniel Moiseev
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Isabella Schena
- Department of Neurology, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Bulat Faezov
- Cancer Biology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Russia
| | - Roland Dunbrack
- Cancer Biology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Jonathan Chernoff
- Cancer Biology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Jun Li
- Department of Neurology, Houston Methodist Research Institute, Houston, TX 77030, USA
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7
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Doan RA, Monk KR. Dock1 acts cell-autonomously in Schwann cells to regulate the development, maintenance, and repair of peripheral myelin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564271. [PMID: 37961336 PMCID: PMC10634861 DOI: 10.1101/2023.10.26.564271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Schwann cells, the myelinating glia of the peripheral nervous system (PNS), are critical for myelin development, maintenance, and repair. Rac1 is a known regulator of radial sorting, a key step in developmental myelination, and we previously showed in zebrafish that loss of Dock1, a Rac1-specific guanine nucleotide exchange factor, results in delayed peripheral myelination in development. We demonstrate here that Dock1 is necessary for myelin maintenance and remyelination after injury in adult zebrafish. Furthermore, it performs an evolutionary conserved role in mice, acting cell-autonomously in Schwann cells to regulate peripheral myelin development, maintenance, and repair. Additionally, manipulating Rac1 levels in larval zebrafish reveals that dock1 mutants are sensitized to inhibition of Rac1, suggesting an interaction between the two proteins during PNS development. We propose that the interplay between Dock1 and Rac1 signaling in Schwann cells is required to establish, maintain, and facilitate repair and remyelination within the peripheral nervous system.
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Affiliation(s)
- Ryan A Doan
- The Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Kelly R Monk
- The Vollum Institute, Oregon Health & Science University, Portland, OR, USA
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8
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Mohamed T, Melfi V, Colciago A, Magnaghi V. Hearing loss and vestibular schwannoma: new insights into Schwann cells implication. Cell Death Dis 2023; 14:629. [PMID: 37741837 PMCID: PMC10517973 DOI: 10.1038/s41419-023-06141-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
Hearing loss (HL) is the most common and heterogeneous disorder of the sensory system, with a large morbidity in the worldwide population. Among cells of the acoustic nerve (VIII cranial nerve), in the cochlea are present the hair cells, the spiral ganglion neurons, the glia-like supporting cells, and the Schwann cells (SCs), which alterations have been considered cause of HL. Notably, a benign SC-derived tumor of the acoustic nerve, named vestibular schwannoma (VS), has been indicated as cause of HL. Importantly, SCs are the main glial cells ensheathing axons and forming myelin in the peripheral nerves. Following an injury, the SCs reprogram, expressing some stemness features. Despite the mechanisms and factors controlling their biological processes (i.e., proliferation, migration, differentiation, and myelination) have been largely unveiled, their role in VS and HL was poorly investigated. In this review, we enlighten some of the mechanisms at the base of SCs transformation, VS development, and progression, likely leading to HL, and we pose great attention on the environmental factors that, in principle, could contribute to HL onset or progression. Combining the biomolecular bench-side approach to the clinical bedside practice may be helpful for the diagnosis, prediction, and therapeutic approach in otology.
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Affiliation(s)
- Tasnim Mohamed
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Via G. Balzaretti 9, 20133, Milan, Italy
| | - Valentina Melfi
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Via G. Balzaretti 9, 20133, Milan, Italy
- Fondazione IRCCS Istituto Nazionale dei Tumori, Via G. Venezian 1, 20133, Milan, Italy
| | - Alessandra Colciago
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Via G. Balzaretti 9, 20133, Milan, Italy
| | - Valerio Magnaghi
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università degli Studi di Milano, Via G. Balzaretti 9, 20133, Milan, Italy.
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9
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Boueid MJ, El-Hage O, Schumacher M, Degerny C, Tawk M. Zebrafish as an emerging model to study estrogen receptors in neural development. Front Endocrinol (Lausanne) 2023; 14:1240018. [PMID: 37664862 PMCID: PMC10469878 DOI: 10.3389/fendo.2023.1240018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 07/27/2023] [Indexed: 09/05/2023] Open
Abstract
Estrogens induce several regulatory signals in the nervous system that are mainly mediated through estrogen receptors (ERs). ERs are largely expressed in the nervous system, yet the importance of ERs to neural development has only been elucidated over the last decades. Accumulating evidence shows a fundamental role for estrogens in the development of the central and peripheral nervous systems, hence, the contribution of ERs to neural function is now a growing area of research. The conservation of the structure of the ERs and their response to estrogens make the zebrafish an interesting model to dissect the role of estrogens in the nervous system. In this review, we highlight major findings of ER signaling in embryonic zebrafish neural development and compare the similarities and differences to research in rodents. We also discuss how the recent generation of zebrafish ER mutants, coupled with the availability of several transgenic reporter lines, its amenability to pharmacological studies and in vivo live imaging, could help us explore ER function in embryonic neural development.
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Affiliation(s)
| | | | | | | | - Marcel Tawk
- *Correspondence: Cindy Degerny, ; Marcel Tawk,
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10
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Vielmuth F, Radeva MY, Yeruva S, Sigmund AM, Waschke J. cAMP: A master regulator of cadherin-mediated binding in endothelium, epithelium and myocardium. Acta Physiol (Oxf) 2023; 238:e14006. [PMID: 37243909 DOI: 10.1111/apha.14006] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/05/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
Regulation of cadherin-mediated cell adhesion is crucial not only for maintaining tissue integrity and barrier function in the endothelium and epithelium but also for electromechanical coupling within the myocardium. Therefore, loss of cadherin-mediated adhesion causes various disorders, including vascular inflammation and desmosome-related diseases such as the autoimmune blistering skin dermatosis pemphigus and arrhythmogenic cardiomyopathy. Mechanisms regulating cadherin-mediated binding contribute to the pathogenesis of diseases and may also be used as therapeutic targets. Over the last 30 years, cyclic adenosine 3',5'-monophosphate (cAMP) has emerged as one of the master regulators of cell adhesion in endothelium and, more recently, also in epithelial cells as well as in cardiomyocytes. A broad spectrum of experimental models from vascular physiology and cell biology applied by different generations of researchers provided evidence that not only cadherins of endothelial adherens junctions (AJ) but also desmosomal contacts in keratinocytes and the cardiomyocyte intercalated discs are central targets in this scenario. The molecular mechanisms involve protein kinase A- and exchange protein directly activated by cAMP-mediated regulation of Rho family GTPases and S665 phosphorylation of the AJ and desmosome adaptor protein plakoglobin. In line with this, phosphodiesterase 4 inhibitors such as apremilast have been proposed as a therapeutic strategy to stabilize cadherin-mediated adhesion in pemphigus and may also be effective to treat other disorders where cadherin-mediated binding is compromised.
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Affiliation(s)
- Franziska Vielmuth
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Mariya Y Radeva
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Sunil Yeruva
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Anna M Sigmund
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Jens Waschke
- Chair of Vegetative Anatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, Munich, Germany
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11
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Schepers M, Malheiro A, Gamardo AS, Hellings N, Prickaerts J, Moroni L, Vanmierlo T, Wieringa P. Phosphodiesterase (PDE) 4 inhibition boosts Schwann cell myelination in a 3D regeneration model. Eur J Pharm Sci 2023; 185:106441. [PMID: 37004962 DOI: 10.1016/j.ejps.2023.106441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/14/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023]
Abstract
Phosphodiesterase 4 (PDE4) inhibitors have been extensively researched for their anti-inflammatory and neuroregenerative properties. Despite the known neuroplastic and myelin regenerative properties of nonselective PDE4 inhibitors on the central nervous system, the direct impact on peripheral remyelination and subsequent neuroregeneration has not yet been investigated. Therefore, to examine the possible therapeutic effect of PDE4 inhibition on peripheral glia, we assessed the differentiation of primary rat Schwann cells exposed in vitro to the PDE4 inhibitor roflumilast. To further investigate the differentiation promoting effects of roflumilast, we developed a 3D model of rat Schwann cell myelination that closely resembles the in vivo situation. Using these in vitro models, we demonstrated that pan-PDE4 inhibition using roflumilast significantly promoted differentiation of Schwann cells towards a myelinating phenotype, as indicated by the upregulation of myelin proteins, including MBP and MAG. Additionally, we created a unique regenerative model comprised of a 3D co-culture of rat Schwann cells and human iPSC-derived neurons. Schwann cells treated with roflumilast enhanced axonal outgrowth of iPSC-derived nociceptive neurons, which was accompanied by an accelerated myelination speed, thereby showing not only phenotypic but also functional changes of roflumilast-treated Schwann cells. Taken together, the PDE4 inhibitor roflumilast possesses a therapeutic benefit to stimulate Schwann cell differentiation and, subsequently myelination, as demonstrated in the biologically relevant in vitro platform used in this study. These results can aid in the development of novel PDE4 inhibition-based therapies in the advancement of peripheral regenerative medicine.
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Affiliation(s)
- Melissa Schepers
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht, MD 6200, the Netherlands; Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium; University MS Center (UMSC) Hasselt-Pelt, Hasselt, Belgium
| | - Afonso Malheiro
- MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, the Netherlands
| | - Adrián Seijas Gamardo
- MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, the Netherlands
| | - Niels Hellings
- Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium; University MS Center (UMSC) Hasselt-Pelt, Hasselt, Belgium
| | - Jos Prickaerts
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht, MD 6200, the Netherlands
| | - Lorenzo Moroni
- MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, the Netherlands
| | - Tim Vanmierlo
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht, MD 6200, the Netherlands; Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium; University MS Center (UMSC) Hasselt-Pelt, Hasselt, Belgium.
| | - Paul Wieringa
- University MS Center (UMSC) Hasselt-Pelt, Hasselt, Belgium
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12
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Hennigan RF, Thomson CS, Stachowski K, Nassar N, Ratner N. Merlin tumor suppressor function is regulated by PIP2-mediated dimerization. PLoS One 2023; 18:e0281876. [PMID: 36809290 PMCID: PMC9942953 DOI: 10.1371/journal.pone.0281876] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 01/30/2023] [Indexed: 02/23/2023] Open
Abstract
Neurofibromatosis Type 2 is an inherited disease characterized by Schwann cell tumors of cranial and peripheral nerves. The NF2 gene encodes Merlin, a member of the ERM family consisting of an N-terminal FERM domain, a central α-helical region, and a C-terminal domain. Changes in the intermolecular FERM-CTD interaction allow Merlin to transition between an open, FERM accessible conformation and a closed, FERM-inaccessible conformation, modulating Merlin activity. Merlin has been shown to dimerize, but the regulation and function Merlin dimerization is not clear. We used a nanobody based binding assay to show that Merlin dimerizes via a FERM-FERM interaction, orientated with each C-terminus close to each other. Patient derived and structural mutants show that dimerization controls interactions with specific binding partners, including HIPPO pathway components, and correlates with tumor suppressor activity. Gel filtration experiments showed that dimerization occurs after a PIP2 mediated transition from closed to open conformation monomers. This process requires the first 18 amino acids of the FERM domain and is inhibited by phosphorylation at serine 518. The discovery that active, open conformation Merlin is a dimer represents a new paradigm for Merlin function with implications for the development of therapies designed to compensate for Merlin loss.
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Affiliation(s)
- Robert F. Hennigan
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
- * E-mail:
| | - Craig S. Thomson
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| | - Kye Stachowski
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| | - Nicolas Nassar
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| | - Nancy Ratner
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
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13
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Hu L, Brichalli W, Li N, Chen S, Cheng Y, Liu Q, Xiong Y, Yu J. Myotubularin functions through actomyosin to interact with the Hippo pathway. EMBO Rep 2022; 23:e55851. [PMID: 36285521 PMCID: PMC9724681 DOI: 10.15252/embr.202255851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/01/2022] [Accepted: 10/07/2022] [Indexed: 12/12/2022] Open
Abstract
The Hippo pathway is an evolutionarily conserved developmental pathway that controls organ size by integrating diverse regulatory inputs, including actomyosin-mediated cytoskeletal tension. Despite established connections between the actomyosin cytoskeleton and the Hippo pathway, the upstream regulation of actomyosin in the Hippo pathway is less defined. Here, we identify the phosphoinositide-3-phosphatase Myotubularin (Mtm) as a novel upstream regulator of actomyosin that functions synergistically with the Hippo pathway during growth control. Mechanistically, Mtm regulates membrane phospholipid PI(3)P dynamics, which, in turn, modulates actomyosin activity through Rab11-mediated vesicular trafficking. We reveal PI(3)P dynamics as a novel mode of upstream regulation of actomyosin and establish Rab11-mediated vesicular trafficking as a functional link between membrane lipid dynamics and actomyosin activation in the context of growth control. Our study also shows that MTMR2, the human counterpart of Drosophila Mtm, has conserved functions in regulating actomyosin activity and tissue growth, providing new insights into the molecular basis of MTMR2-related peripheral nerve myelination and human disorders.
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Affiliation(s)
- Liang Hu
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - Wyatt Brichalli
- Department of Anatomy & PhysiologyKansas State University College of Veterinary MedicineManhattanKSUSA
| | - Naren Li
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - Shifan Chen
- Department of NeuroscienceUniversity of Connecticut School of MedicineFarmingtonCTUSA
| | - Yaqing Cheng
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - Qinfang Liu
- Department of NeuroscienceUniversity of Connecticut School of MedicineFarmingtonCTUSA
| | - Yulan Xiong
- Department of NeuroscienceUniversity of Connecticut School of MedicineFarmingtonCTUSA
| | - Jianzhong Yu
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
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14
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Cristobal CD, Lee HK. Development of myelinating glia: An overview. Glia 2022; 70:2237-2259. [PMID: 35785432 PMCID: PMC9561084 DOI: 10.1002/glia.24238] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/24/2022] [Accepted: 06/24/2022] [Indexed: 01/07/2023]
Abstract
Myelin is essential to nervous system function, playing roles in saltatory conduction and trophic support. Oligodendrocytes (OLs) and Schwann cells (SCs) form myelin in the central and peripheral nervous systems respectively and follow different developmental paths. OLs are neural stem-cell derived and follow an intrinsic developmental program resulting in a largely irreversible differentiation state. During embryonic development, OL precursor cells (OPCs) are produced in distinct waves originating from different locations in the central nervous system, with a subset developing into myelinating OLs. OPCs remain evenly distributed throughout life, providing a population of responsive, multifunctional cells with the capacity to remyelinate after injury. SCs derive from the neural crest, are highly dependent on extrinsic signals, and have plastic differentiation states. SC precursors (SCPs) are produced in early embryonic nerve structures and differentiate into multipotent immature SCs (iSCs), which initiate radial sorting and differentiate into myelinating and non-myelinating SCs. Differentiated SCs retain the capacity to radically change phenotypes in response to external signals, including becoming repair SCs, which drive peripheral regeneration. While several transcription factors and myelin components are common between OLs and SCs, their differentiation mechanisms are highly distinct, owing to their unique lineages and their respective environments. In addition, both OLs and SCs respond to neuronal activity and regulate nervous system output in reciprocal manners, possibly through different pathways. Here, we outline their basic developmental programs, mechanisms regulating their differentiation, and recent advances in the field.
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Affiliation(s)
- Carlo D. Cristobal
- Integrative Program in Molecular and Biomedical SciencesBaylor College of MedicineHoustonTexasUSA,Jan and Dan Duncan Neurological Research InstituteTexas Children's HospitalHoustonTexasUSA
| | - Hyun Kyoung Lee
- Integrative Program in Molecular and Biomedical SciencesBaylor College of MedicineHoustonTexasUSA,Jan and Dan Duncan Neurological Research InstituteTexas Children's HospitalHoustonTexasUSA,Department of PediatricsBaylor College of MedicineHoustonTexasUSA,Department of NeuroscienceBaylor College of MedicineHoustonTexasUSA
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15
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Borger A, Stadlmayr S, Haertinger M, Semmler L, Supper P, Millesi F, Radtke C. How miRNAs Regulate Schwann Cells during Peripheral Nerve Regeneration-A Systemic Review. Int J Mol Sci 2022; 23:3440. [PMID: 35408800 PMCID: PMC8999002 DOI: 10.3390/ijms23073440] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 01/18/2023] Open
Abstract
A growing body of studies indicate that small noncoding RNAs, especially microRNAs (miRNA), play a crucial role in response to peripheral nerve injuries. During Wallerian degeneration and regeneration processes, they orchestrate several pathways, in particular the MAPK, AKT, and EGR2 (KROX20) pathways. Certain miRNAs show specific expression profiles upon a nerve lesion correlating with the subsequent nerve regeneration stages such as dedifferentiation and with migration of Schwann cells, uptake of debris, neurite outgrowth and finally remyelination of regenerated axons. This review highlights (a) the specific expression profiles of miRNAs upon a nerve lesion and (b) how miRNAs regulate nerve regeneration by acting on distinct pathways and linked proteins. Shedding light on the role of miRNAs associated with peripheral nerve regeneration will help researchers to better understand the molecular mechanisms and deliver targets for precision medicine.
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Affiliation(s)
- Anton Borger
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
| | - Sarah Stadlmayr
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
| | - Maximilian Haertinger
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
| | - Lorenz Semmler
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
| | - Paul Supper
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
| | - Flavia Millesi
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
| | - Christine Radtke
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; (A.B.); (S.S.); (M.H.); (L.S.); (P.S.); (F.M.)
- Austrian Cluster for Tissue Regeneration, 1090 Vienna, Austria
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16
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Wrestling and Wrapping: A Perspective on SUMO Proteins in Schwann Cells. Biomolecules 2021; 11:biom11071055. [PMID: 34356679 PMCID: PMC8301837 DOI: 10.3390/biom11071055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 11/20/2022] Open
Abstract
Schwann cell development and peripheral nerve myelination are finely orchestrated multistep processes; some of the underlying mechanisms are well described and others remain unknown. Many posttranslational modifications (PTMs) like phosphorylation and ubiquitination have been reported to play a role during the normal development of the peripheral nervous system (PNS) and in demyelinating neuropathies. However, a relatively novel PTM, SUMOylation, has not been studied in these contexts. SUMOylation involves the covalent attachment of one or more small ubiquitin-like modifier (SUMO) proteins to a substrate, which affects the function, cellular localization, and further PTMs of the conjugated protein. SUMOylation also regulates other proteins indirectly by facilitating non-covalent protein–protein interaction via SUMO interaction motifs (SIM). This pathway has important consequences on diverse cellular processes, and dysregulation of this pathway has been reported in several diseases including neurological and degenerative conditions. In this article, we revise the scarce literature on SUMOylation in Schwann cells and the PNS, we propose putative substrate proteins, and we speculate on potential mechanisms underlying the possible involvement of this PTM in peripheral myelination and neuropathies.
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17
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Heinrich A, Potter SJ, Guo L, Ratner N, DeFalco T. Distinct Roles for Rac1 in Sertoli Cell Function during Testicular Development and Spermatogenesis. Cell Rep 2021; 31:107513. [PMID: 32294451 PMCID: PMC7213061 DOI: 10.1016/j.celrep.2020.03.077] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 01/16/2020] [Accepted: 03/24/2020] [Indexed: 01/15/2023] Open
Abstract
Sertoli cells are supporting cells of the testicular seminiferous tubules, which provide a nurturing environment for spermatogenesis. Adult Sertoli cells are polarized so that they can simultaneously support earlier-stage spermatogenic cells (e.g., spermatogonia) basally and later-stage cells (e.g., spermatids) apically. To test the consequences of disrupting cell polarity in Sertoli cells, we perform a Sertoli-specific conditional deletion of Rac1, which encodes a Rho GTPase required for apicobasal cell polarity. Rac1 conditional knockout adults exhibit spermatogenic arrest at the round spermatid stage, with severe disruption of Sertoli cell polarity, and show increased germline and Sertoli cell apoptosis. Thus, Sertoli Rac1 function is critical for the progression of spermatogenesis but, surprisingly, is dispensable for fetal testicular development, adult maintenance of undifferentiated spermatogonia, and meiotic entry. Our data indicate that Sertoli Rac1 function is required only for certain aspects of spermatogenesis and reveal that there are distinct requirements for cell polarity during cellular differentiation.
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Affiliation(s)
- Anna Heinrich
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Sarah J Potter
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Li Guo
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Nancy Ratner
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Tony DeFalco
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
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18
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Pellegatta M, Berti C, Hurley E, Palmisano M, de Curtis I, Feltri ML, Frick LR. Rac1 and Rac3 have opposite functions in Schwann cells during developmental myelination. Neurosci Lett 2021; 753:135868. [PMID: 33812927 DOI: 10.1016/j.neulet.2021.135868] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/14/2021] [Accepted: 03/29/2021] [Indexed: 11/15/2022]
Abstract
Small Rho GTPases such as Cdc42 and Rac1 regulate peripheral myelination during development. Deletion of Rac1 in Schwann cell conditional knockout mice causes a delay in the process of radial sorting, followed by hypomyelination as well as defective PAK1 activation and high number of immature Oct6+ Schwann cells. Rac3 has been shown to have redundant, specific and even opposite functions to Rac1 depending on the cell type, age and other factors. In neuronal cells, evidence suggests that Rac3 may oppose Rac1 by disrupting PAK1-GIT1-Paxillin signaling thus preventing cell differentiation and extension of lamellipodia. Therefore, we tested if these Rho GTPases have similar or opposite functions in Schwann cells, by deleting the genes for both proteins in mice during peripheral myelination. At P30, global deletion of Rac3 alleviates the developmental defects on axonal sorting and hypomyelination that are caused by Schwann cell conditional ablation of Rac1. Moreover, Rac3 deletion also reverses the arrest of Schwann cells at the Oct6+ stage and ameliorates the defects in PAK1 phosphorylation observed in Rac1 deficient mice. This partial rescue of the phenotype declines later on with aging. Since double transgenic animals showed dysmyelination without axonal degeneration at P60, we postulate that this deterioration is not likely due to loss of Rac3 in neurons, but it seems to be a Schwann cell-specific defect in the maintenance of myelin.
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Affiliation(s)
- Marta Pellegatta
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Biochemistry Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States
| | - Caterina Berti
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States
| | - Edward Hurley
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States
| | - Marilena Palmisano
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Biochemistry Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States
| | - Ivan de Curtis
- San Raffaele Hospital, Division of Neuroscience, Milano, 20132, Italy
| | - M Laura Feltri
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Biochemistry Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States
| | - Luciana R Frick
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States; Departments of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, 14203, United States.
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19
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Feltri ML, Weaver MR, Belin S, Poitelon Y. The Hippo pathway: Horizons for innovative treatments of peripheral nerve diseases. J Peripher Nerv Syst 2021; 26:4-16. [PMID: 33449435 DOI: 10.1111/jns.12431] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/16/2020] [Accepted: 12/20/2020] [Indexed: 12/19/2022]
Abstract
Initially identified in Drosophila, the Hippo signaling pathway regulates how cells respond to their environment by controlling proliferation, migration and differentiation. Many recent studies have focused on characterizing Hippo pathway function and regulation in mammalian cells. Here, we present a brief overview of the major components of the Hippo pathway, as well as their regulation and function. We comprehensively review the studies that have contributed to our understanding of the Hippo pathway in the function of the peripheral nervous system and in peripheral nerve diseases. Finally, we discuss innovative approaches that aim to modulate Hippo pathway components in diseases of the peripheral nervous system.
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Affiliation(s)
- M Laura Feltri
- Hunter James Kelly Research Institute, Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York, USA.,Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York, USA
| | - Michael R Weaver
- Hunter James Kelly Research Institute, Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York, USA
| | - Sophie Belin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Yannick Poitelon
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
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20
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Won SY, Kwon S, Jeong HS, Chung KW, Choi B, Chang JW, Lee JE. Fibulin 5, a human Wharton's jelly-derived mesenchymal stem cells-secreted paracrine factor, attenuates peripheral nervous system myelination defects through the Integrin-RAC1 signaling axis. Stem Cells 2020; 38:1578-1593. [PMID: 33107705 PMCID: PMC7756588 DOI: 10.1002/stem.3287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/15/2020] [Accepted: 09/22/2020] [Indexed: 04/25/2023]
Abstract
In the peripheral nervous system (PNS), proper development of Schwann cells (SCs) contributing to axonal myelination is critical for neuronal function. Impairments of SCs or neuronal axons give rise to several myelin-related disorders, including dysmyelinating and demyelinating diseases. Pathological mechanisms, however, have been understood at the elementary level and targeted therapeutics has remained undeveloped. Here, we identify Fibulin 5 (FBLN5), an extracellular matrix (ECM) protein, as a key paracrine factor of human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) to control the development of SCs. We show that co-culture with WJ-MSCs or treatment of recombinant FBLN5 promotes the proliferation of SCs through ERK activation, whereas FBLN5-depleted WJ-MSCs do not. We further reveal that during myelination of SCs, FBLN5 binds to Integrin and modulates actin remodeling, such as the formation of lamellipodia and filopodia, through RAC1 activity. Finally, we show that FBLN5 effectively restores the myelination defects of SCs in the zebrafish model of Charcot-Marie-Tooth (CMT) type 1, a representative demyelinating disease. Overall, our data propose human WJ-MSCs or FBLN5 protein as a potential treatment for myelin-related diseases, including CMT.
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Affiliation(s)
- So Yeon Won
- Department of Health Sciences and TechnologySamsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan UniversitySeoulSouth Korea
| | - Soojin Kwon
- Stem Cell & Regenerative Medicine Institute, Samsung Medical CenterSeoulSouth Korea
- Stem Cell Institute, ENCell Co. LtdSeoulSouth Korea
| | - Hui Su Jeong
- Department of Health Sciences and TechnologySamsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan UniversitySeoulSouth Korea
| | - Ki Wha Chung
- Department of Biological SciencesKongju National UniversityKongjuSouth Korea
| | - Byung‐Ok Choi
- Department of NeurologySungkyunkwan University School of MedicineSeoulSouth Korea
| | - Jong Wook Chang
- Stem Cell & Regenerative Medicine Institute, Samsung Medical CenterSeoulSouth Korea
- Stem Cell Institute, ENCell Co. LtdSeoulSouth Korea
| | - Ji Eun Lee
- Department of Health Sciences and TechnologySamsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan UniversitySeoulSouth Korea
- Samsung Biomedical Research Institute, Samsung Medical CenterSeoulSouth Korea
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21
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SOX10-regulated promoter use defines isoform-specific gene expression in Schwann cells. BMC Genomics 2020; 21:549. [PMID: 32770939 PMCID: PMC7430845 DOI: 10.1186/s12864-020-06963-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/29/2020] [Indexed: 01/12/2023] Open
Abstract
Background Multicellular organisms adopt various strategies to tailor gene expression to cellular contexts including the employment of multiple promoters (and the associated transcription start sites (TSSs)) at a single locus that encodes distinct gene isoforms. Schwann cells—the myelinating cells of the peripheral nervous system (PNS)—exhibit a specialized gene expression profile directed by the transcription factor SOX10, which is essential for PNS myelination. SOX10 regulates promoter elements associated with unique TSSs and gene isoforms at several target loci, implicating SOX10-mediated, isoform-specific gene expression in Schwann cell function. Here, we report on genome-wide efforts to identify SOX10-regulated promoters and TSSs in Schwann cells to prioritize genes and isoforms for further study. Results We performed global TSS analyses and mined previously reported ChIP-seq datasets to assess the activity of SOX10-bound promoters in three models: (i) an adult mammalian nerve; (ii) differentiating primary Schwann cells, and (iii) cultured Schwann cells with ablated SOX10 function. We explored specific characteristics of SOX10-dependent TSSs, which provides confidence in defining them as SOX10 targets. Finally, we performed functional studies to validate our findings at four previously unreported SOX10 target loci: ARPC1A, CHN2, DDR1, and GAS7. These findings suggest roles for the associated SOX10-regulated gene products in PNS myelination. Conclusions In sum, we provide comprehensive computational and functional assessments of SOX10-regulated TSS use in Schwann cells. The data presented in this study will stimulate functional studies on the specific mRNA and protein isoforms that SOX10 regulates, which will improve our understanding of myelination in the peripheral nerve.
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22
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Mund JA, Park S, Smith AE, He Y, Jiang L, Hawley E, Roberson MJ, Mitchell DK, Abu-Sultanah M, Yuan J, Bessler WK, Sandusky G, Chen S, Zhang C, Rhodes SD, Clapp DW. Genetic disruption of the small GTPase RAC1 prevents plexiform neurofibroma formation in mice with neurofibromatosis type 1. J Biol Chem 2020; 295:9948-9958. [PMID: 32471868 PMCID: PMC7380178 DOI: 10.1074/jbc.ra119.010981] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 05/27/2020] [Indexed: 12/13/2022] Open
Abstract
Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome caused by mutations in the NF1 tumor suppressor gene. NF1 encodes neurofibromin, a GTPase-activating protein for RAS proto-oncogene GTPase (RAS). Plexiform neurofibromas are a hallmark of NF1 and result from loss of heterozygosity of NF1 in Schwann cells, leading to constitutively activated p21RAS. Given the inability to target p21RAS directly, here we performed an shRNA library screen of all human kinases and Rho-GTPases in a patient-derived NF1-/- Schwann cell line to identify novel therapeutic targets to disrupt PN formation and progression. Rho family members, including Rac family small GTPase 1 (RAC1), were identified as candidates. Corroborating these findings, we observed that shRNA-mediated knockdown of RAC1 reduces cell proliferation and phosphorylation of extracellular signal-regulated kinase (ERK) in NF1-/- Schwann cells. Genetically engineered Nf1flox/flox;PostnCre+ mice, which develop multiple PNs, also exhibited increased RAC1-GTP and phospho-ERK levels compared with Nf1flox/flox;PostnCre- littermates. Notably, mice in which both Nf1 and Rac1 loci were disrupted (Nf1flox/floxRac1flox/flox;PostnCre+) were completely free of tumors and had normal phospho-ERK activity compared with Nf1flox/flox ;PostnCre+ mice. We conclude that the RAC1-GTPase is a key downstream node of RAS and that genetic disruption of the Rac1 allele completely prevents PN tumor formation in vivo in mice.
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Affiliation(s)
- Julie A Mund
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - SuJung Park
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Abbi E Smith
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yongzheng He
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Li Jiang
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Eric Hawley
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Michelle J Roberson
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Dana K Mitchell
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Mohannad Abu-Sultanah
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jin Yuan
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Waylan K Bessler
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - George Sandusky
- Division of Pediatric Hematology-Oncology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Shi Chen
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
| | - Chi Zhang
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Steven D Rhodes
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - D Wade Clapp
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
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23
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Chen S, Wu C, Liu A, Wei D, Xiao Y, Guo Z, Chen L, Zhu Y, Sun J, Luo H, Fan H. Biofabrication of nerve fibers with mimetic myelin sheath-like structure and aligned fibrous niche. Biofabrication 2020; 12:035013. [PMID: 32240990 DOI: 10.1088/1758-5090/ab860d] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nerve tissues contain hierarchically ordered nerve fibers, while each of the nerve fibers has nano-oriented fibrous extracellular matrix and a core-shell structure of tubular myelin sheath with elongated axons encapsulated. Here, we report, for the first time, a ready approach to fabricate biomimetic nerve fibers which are oriented and have a core-shell structure to spatially encapsulate two types of cells, neurons and Schwann cells. A microfluidic system was designed and assembled, which contained a coaxial triple-channel chip and a stretching loading device. Alginate was used first to assist the fabrication, which was washed away afterwards. The orientation of the biomimetic nerve fibers was optimized by the control of the compositions of methacrylate hyaluronan and fibrin, together with the parameters of microfluidic shearing and external stretching. Also, neurons and Schwann cells, which were respectively located in the core and shell of the fibers, displayed advanced biologic functions, including neurogenesis and myelinating maturation. We demonstrate that the neural performance is relatively good, compared to that resulted from individually encapsulated in single-layer microfibers. The present study brings insights to fabricate biomimetic nerve fibers for their potential in neuroscience research and nerve regeneration. Moreover, the present methodology on the fabrication of oriented fibers with different types of cells separately encapsulated should be applicable to biomimetic constructions of various tissues.
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Affiliation(s)
- Suping Chen
- Engineering Research Center in Biomaterials, Sichuan University, Chengdu, Sichuan 610064 People's Republic of China
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24
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Exosomes derived from differentiated Schwann cells inhibit Schwann cell migration via microRNAs. Neuroreport 2020; 31:515-522. [DOI: 10.1097/wnr.0000000000001435] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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25
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Zhang Z, Li X, Li A, Wu G. miR-485-5p suppresses Schwann cell proliferation and myelination by targeting cdc42 and Rac1. Exp Cell Res 2020; 388:111803. [DOI: 10.1016/j.yexcr.2019.111803] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/20/2019] [Accepted: 12/22/2019] [Indexed: 10/25/2022]
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26
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Mikdache A, Fontenas L, Albadri S, Revenu C, Loisel-Duwattez J, Lesport E, Degerny C, Del Bene F, Tawk M. Elmo1 function, linked to Rac1 activity, regulates peripheral neuronal numbers and myelination in zebrafish. Cell Mol Life Sci 2020; 77:161-177. [PMID: 31161284 PMCID: PMC11104998 DOI: 10.1007/s00018-019-03167-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 05/28/2019] [Accepted: 05/28/2019] [Indexed: 12/20/2022]
Abstract
Peripheral nervous system development involves a tight coordination of neuronal birth and death and a substantial remodelling of the myelinating glia cytoskeleton to achieve myelin wrapping of its projecting axons. However, how these processes are coordinated through time is still not understood. We have identified engulfment and cell motility 1, Elmo1, as a novel component that regulates (i) neuronal numbers within the Posterior Lateral Line ganglion and (ii) radial sorting of axons by Schwann cells (SC) and myelination in the PLL system in zebrafish. Our results show that neuronal and myelination defects observed in elmo1 mutant are rescued through small GTPase Rac1 activation. Inhibiting macrophage development leads to a decrease in neuronal numbers, while peripheral myelination is intact. However, elmo1 mutants do not show defective macrophage activity, suggesting a role for Elmo1 in PLLg neuronal development and SC myelination independent of macrophages. Forcing early Elmo1 and Rac1 expression specifically within SCs rescues elmo1-/- myelination defects, highlighting an autonomous role for Elmo1 and Rac1 in radial sorting of axons by SCs and myelination. This uncovers a previously unknown function of Elmo1 that regulates fundamental aspects of PNS development.
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Affiliation(s)
- Aya Mikdache
- U1195, Inserm, University Paris Sud, University Paris-Saclay, 94276, Le Kremlin Bicêtre, France
| | - Laura Fontenas
- U1195, Inserm, University Paris Sud, University Paris-Saclay, 94276, Le Kremlin Bicêtre, France
- Department of Biology, University of Virginia, Charlottesville, VA, 22904-4328, USA
| | - Shahad Albadri
- Institut Curie, PSL Research University, 75005, Paris, France
| | - Celine Revenu
- Institut Curie, PSL Research University, 75005, Paris, France
| | - Julien Loisel-Duwattez
- U1195, Inserm, University Paris Sud, University Paris-Saclay, 94276, Le Kremlin Bicêtre, France
| | - Emilie Lesport
- U1195, Inserm, University Paris Sud, University Paris-Saclay, 94276, Le Kremlin Bicêtre, France
| | - Cindy Degerny
- U1195, Inserm, University Paris Sud, University Paris-Saclay, 94276, Le Kremlin Bicêtre, France
| | | | - Marcel Tawk
- U1195, Inserm, University Paris Sud, University Paris-Saclay, 94276, Le Kremlin Bicêtre, France.
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27
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Torii T, Miyamoto Y, Yamauchi J. Cellular Signal-Regulated Schwann Cell Myelination and Remyelination. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:3-22. [PMID: 31760634 DOI: 10.1007/978-981-32-9636-7_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Increasing studies have demonstrated multiple signaling molecules responsible for oligodendrocytes and Schwann cells development such as migration, differentiation, myelination, and axo-glial interaction. However, complicated roles in these events are still poorly understood. This chapter focuses on well established intracellular signaling transduction and recent topics that control myelination and are elucidated from accumulating evidences. The underlying molecular mechanisms, which involved in membrane trafficking through small GTPase Arf6 and its activator cytohesins, demonstrate the crosstalk between well established intracellular signaling transduction and a new finding signaling pathway in glial cells links to physiological phenotype and essential role in peripheral nerve system (PNS). Since Arf family proteins affect the expression levels of myelin protein zero (MPZ) and Krox20, which is a transcription factor regulatory factor in early developmental stages of Schwann cells, Arf proteins likely to be key regulator for Schwann cells development. Herein, we discuss how intracellular signaling transductions in Schwann cells associate with myelination in CNS and PNS.
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Affiliation(s)
- Tomohiro Torii
- Graduate School of Brain Science, Doshisha University, Kyotanabe-shi, Kyoto, Japan
| | - Yuki Miyamoto
- Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan
| | - Junji Yamauchi
- Laboratory of Molecular Neuroscience and Neurology, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo, Japan.
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28
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Mehrotra P, Tseropoulos G, Bronner ME, Andreadis ST. Adult tissue-derived neural crest-like stem cells: Sources, regulatory networks, and translational potential. Stem Cells Transl Med 2019; 9:328-341. [PMID: 31738018 PMCID: PMC7031649 DOI: 10.1002/sctm.19-0173] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 10/22/2019] [Accepted: 10/25/2019] [Indexed: 12/15/2022] Open
Abstract
Neural crest (NC) cells are a multipotent stem cell population that give rise to a diverse array of cell types in the body, including peripheral neurons, Schwann cells (SC), craniofacial cartilage and bone, smooth muscle cells, and melanocytes. NC formation and differentiation into specific lineages takes place in response to a set of highly regulated signaling and transcriptional events within the neural plate border. Premigratory NC cells initially are contained within the dorsal neural tube from which they subsequently emigrate, migrating to often distant sites in the periphery. Following their migration and differentiation, some NC‐like cells persist in adult tissues in a nascent multipotent state, making them potential candidates for autologous cell therapy. This review discusses the gene regulatory network responsible for NC development and maintenance of multipotency. We summarize the genes and signaling pathways that have been implicated in the differentiation of a postmigratory NC into mature myelinating SC. We elaborate on the signals and transcription factors involved in the acquisition of immature SC fate, axonal sorting of unmyelinated neuronal axons, and finally the path toward mature myelinating SC, which envelope axons within myelin sheaths, facilitating electrical signal propagation. The gene regulatory events guiding development of SC in vivo provides insights into means for differentiating NC‐like cells from adult human tissues into functional SC, which have the potential to provide autologous cell sources for the treatment of demyelinating and neurodegenerative disorders.
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Affiliation(s)
- Pihu Mehrotra
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York
| | - Georgios Tseropoulos
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California
| | - Stelios T Andreadis
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York.,Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York.,Department of Biomedical Engineering, University at Buffalo, Buffalo, New York
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29
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Bradley EC, Cunningham RL, Wilde C, Morgan RK, Klug EA, Letcher SM, Schöneberg T, Monk KR, Liebscher I, Petersen SC. In vivo identification of small molecules mediating Gpr126/Adgrg6 signaling during Schwann cell development. Ann N Y Acad Sci 2019; 1456:44-63. [PMID: 31529518 PMCID: PMC7189964 DOI: 10.1111/nyas.14233] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/30/2019] [Accepted: 08/26/2019] [Indexed: 12/13/2022]
Abstract
Gpr126/Adgrg6, an adhesion family G protein-coupled receptor (aGPCR), is required for the development of myelinating Schwann cells in the peripheral nervous system. Myelin supports and insulates vertebrate axons to permit rapid signal propagation throughout the nervous system. In mammals and zebrafish, mutations in Gpr126 arrest Schwann cells at early developmental stages. We exploited the optical and pharmacological tractability of larval zebrafish to uncover drugs that mediate myelination by activating Gpr126 or functioning in parallel. Using a fluorescent marker of mature myelinating glia (Tg[mbp:EGFP-CAAX]), we screened hypomorphic gpr126 mutant larvae for restoration of myelin basic protein (mbp) expression along peripheral nerves following small molecule treatment. Our screens identified five compounds sufficient to promote mbp expression in gpr126 hypomorphs. Using an allelic series of gpr126 mutants, we parsed the ability of small molecules to restore mbp, suggesting differences in drug efficacy dependent on Schwann cell developmental state. Finally, we identify apomorphine hydrochloride as a direct small molecule activator of Gpr126 using combined in vivo/in vitro assays and show that aporphine class compounds promote Schwann cell development in vivo. Our results demonstrate the utility of in vivo screening for aGPCR modulators and identify small molecules that interact with the gpr126-mediated myelination program.
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Affiliation(s)
| | - Rebecca L. Cunningham
- Department of Developmental Biology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Caroline Wilde
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Rory K. Morgan
- Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Emma A. Klug
- Department of Neuroscience, Kenyon College, Gambier, OH, USA
| | | | - Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Kelly R. Monk
- Department of Developmental Biology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
- Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Ines Liebscher
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Sarah C. Petersen
- Department of Neuroscience, Kenyon College, Gambier, OH, USA
- Department of Developmental Biology, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
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30
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Galino J, Cervellini I, Zhu N, Stöberl N, Hütte M, Fricker FR, Lee G, McDermott L, Lalli G, Bennett DLH. RalGTPases contribute to Schwann cell repair after nerve injury via regulation of process formation. J Cell Biol 2019; 218:2370-2387. [PMID: 31201266 PMCID: PMC6605803 DOI: 10.1083/jcb.201811002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 04/10/2019] [Accepted: 05/15/2019] [Indexed: 12/02/2022] Open
Abstract
RalA and RalB are involved in cell migration and membrane dynamics. This study finds that ablation of RalGTPases impairs nerve regeneration and alters Schwann cell process formation; conversely, activation of RalGTPases enhancea Schwann cell process formation, migration, and axon myelination. RalA and RalB are small GTPases that are involved in cell migration and membrane dynamics. We used transgenic mice in which one or both GTPases were genetically ablated to investigate the role of RalGTPases in the Schwann cell (SC) response to nerve injury and repair. RalGTPases were dispensable for SC function in the naive uninjured state. Ablation of both RalA and RalB (but not individually) in SCs resulted in impaired axon remyelination and target reinnervation following nerve injury, which resulted in slowed recovery of motor function. Ral GTPases were localized to the leading lamellipodia in SCs and were required for the formation and extension of both axial and radial processes of SCs. These effects were dependent on interaction with the exocyst complex and impacted on the rate of SC migration and myelination. Our results show that RalGTPases are required for efficient nerve repair by regulating SC process formation, migration, and myelination, therefore uncovering a novel role for these GTPases.
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Affiliation(s)
- Jorge Galino
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Ilaria Cervellini
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Ning Zhu
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Nina Stöberl
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Meike Hütte
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Florence R Fricker
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Garrett Lee
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Lucy McDermott
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Giovanna Lalli
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London, UK
| | - David L H Bennett
- The Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
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31
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Terada N, Saitoh Y, Kamijo A, Yamauchi J, Ohno N, Sakamoto T. Structures and Molecular Composition of Schmidt-Lanterman Incisures. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:181-198. [PMID: 31760645 DOI: 10.1007/978-981-32-9636-7_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Schmidt-Lanterman incisure (SLI) is a circular-truncated cone shape in the myelin internode that is a specific feature of myelinated nerve fibers formed in Schwann cells in the peripheral nervous system (PNS). The SLI circular-truncated cones elongate like spring at the narrow sites of beaded appearance nerve fibers under the stretched condition. In this chapter, we demonstrate various molecular complexes in SLI, and especially focus on membrane skeleton, protein 4.1G-membrane protein palmitoylated 6 (MPP6)-cell adhesion molecule 4 (CADM4). 4.1G was essential for the molecular targeting of MPP6 and CADM4 in SLI. Motor activity and myelin ultrastructures were abnormal in 4.1G-deficient mice, indicating the 4.1G function as a signal for proper formation of myelin in PNS. Thus, SLI probably has potential roles in the regulation of adhesion and signal transduction as well as in structural stability in Schwann cell myelin formation.
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Affiliation(s)
- Nobuo Terada
- Health Science Division, Department of Medical Sciences, Shinshu University Graduate School of Medicine, Science and Technology, Matsumoto City, Nagano, Japan.
| | - Yurika Saitoh
- Health Science Division, Department of Medical Sciences, Shinshu University Graduate School of Medicine, Science and Technology, Matsumoto City, Nagano, Japan
- Center for Medical Education, Teikyo University of Science, Adachi-ku, Tokyo, Japan
| | - Akio Kamijo
- Health Science Division, Department of Medical Sciences, Shinshu University Graduate School of Medicine, Science and Technology, Matsumoto City, Nagano, Japan
| | - Junji Yamauchi
- Laboratory of Molecular Neuroscience and Neurology, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo, Japan
| | - Nobuhiko Ohno
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine, Shimotsuke, Japan
| | - Takeharu Sakamoto
- Division of Cellular and Molecular Biology, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan
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32
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Cunningham RL, Herbert AL, Harty BL, Ackerman SD, Monk KR. Mutations in dock1 disrupt early Schwann cell development. Neural Dev 2018; 13:17. [PMID: 30089513 PMCID: PMC6083577 DOI: 10.1186/s13064-018-0114-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/20/2018] [Indexed: 01/29/2023] Open
Abstract
Background In the peripheral nervous system (PNS), specialized glial cells called Schwann cells produce myelin, a lipid-rich insulating sheath that surrounds axons and promotes rapid action potential propagation. During development, Schwann cells must undergo extensive cytoskeletal rearrangements in order to become mature, myelinating Schwann cells. The intracellular mechanisms that drive Schwann cell development, myelination, and accompanying cell shape changes are poorly understood. Methods Through a forward genetic screen in zebrafish, we identified a mutation in the atypical guanine nucleotide exchange factor, dock1, that results in decreased myelination of peripheral axons. Rescue experiments and complementation tests with newly engineered alleles confirmed that mutations in dock1 cause defects in myelination of the PNS. Whole mount in situ hybridization, transmission electron microscopy, and live imaging were used to fully define mutant phenotypes. Results We show that Schwann cells in dock1 mutants can appropriately migrate and are not decreased in number, but exhibit delayed radial sorting and decreased myelination during early stages of development. Conclusions Together, our results demonstrate that mutations in dock1 result in defects in Schwann cell development and myelination. Specifically, loss of dock1 delays radial sorting and myelination of peripheral axons in zebrafish. Electronic supplementary material The online version of this article (10.1186/s13064-018-0114-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rebecca L Cunningham
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Amy L Herbert
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Breanne L Harty
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Sarah D Ackerman
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Institute of Neuroscience, University of Oregon, Eugene, OR, 97403, USA
| | - Kelly R Monk
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA. .,Vollum Institute, Oregon Health and Science University, Portland, OR, 97239, USA.
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33
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Wright AA, Todorovic M, Tello-Velasquez J, Rayfield AJ, St John JA, Ekberg JA. Enhancing the Therapeutic Potential of Olfactory Ensheathing Cells in Spinal Cord Repair Using Neurotrophins. Cell Transplant 2018; 27:867-878. [PMID: 29852748 PMCID: PMC6050907 DOI: 10.1177/0963689718759472] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Autologous olfactory ensheathing cell (OEC) transplantation is a promising therapy for
spinal cord injury; however, the efficacy varies between trials in both animals and
humans. The main reason for this variability is that the purity and phenotype of the
transplanted cells differs between studies. OECs are susceptible to modulation with
neurotrophic factors, and thus, neurotrophins can be used to manipulate the transplanted
cells into an optimal, consistent phenotype. OEC transplantation can be divided into 3
phases: (1) cell preparation, (2) cell administration, and (3) continuous support to the
transplanted cells in situ. The ideal behaviour of OECs differs between these 3 phases; in
the cell preparation phase, rapid cell expansion is desirable to decrease the time between
damage and transplantation. In the cell administration phase, OEC survival and integration
at the injury site, in particular migration into the glial scar, are the most critical
factors, along with OEC-mediated phagocytosis of cellular debris. Finally, continuous
support needs to be provided to the transplantation site to promote survival of both
transplanted cells and endogenous cells within injury site and to promote long-term
integration of the transplanted cells and angiogenesis. In this review, we define the 3
phases of OEC transplantation into the injured spinal cord and the optimal cell behaviors
required for each phase. Optimising functional outcomes of OEC transplantation can be
achieved by modulation of cell behaviours with neurotrophins. We identify the key growth
factors that exhibit the strongest potential for optimizing the OEC phenotype required for
each phase.
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Affiliation(s)
- A A Wright
- 1 Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - M Todorovic
- 1 Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia.,2 Menzies Health Institute Queensland, Griffith University, Southport, Queensland, Australia
| | - J Tello-Velasquez
- 1 Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - A J Rayfield
- 1 Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia.,2 Menzies Health Institute Queensland, Griffith University, Southport, Queensland, Australia
| | - J A St John
- 1 Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia.,2 Menzies Health Institute Queensland, Griffith University, Southport, Queensland, Australia
| | - J A Ekberg
- 1 Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia.,2 Menzies Health Institute Queensland, Griffith University, Southport, Queensland, Australia
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Dalal S, Connelly B, Singh M, Singh K. NF2 signaling pathway plays a pro-apoptotic role in β-adrenergic receptor stimulated cardiac myocyte apoptosis. PLoS One 2018; 13:e0196626. [PMID: 29709009 PMCID: PMC5927447 DOI: 10.1371/journal.pone.0196626] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/16/2018] [Indexed: 12/24/2022] Open
Abstract
β-adrenergic receptor (β-AR) stimulation induces cardiac myocyte apoptosis in vitro and in vivo. Neurofibromin 2 (NF2) is a member of the ezrin/radixin/moesin (ERM) family of proteins. Post-translational modifications such as phosphorylation and sumoylation affect NF2 activity, subcellular localization and function. Here, we tested the hypothesis that β-AR stimulation induces post-translational modifications of NF2, and NF2 plays a pro-apoptotic role in β-AR-stimulated myocyte apoptosis.
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Affiliation(s)
- Suman Dalal
- Department of Biomedical Sciences, James H Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Barbara Connelly
- Department of Biomedical Sciences, James H Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Mahipal Singh
- Department of Biomedical Sciences, James H Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
| | - Krishna Singh
- Department of Biomedical Sciences, James H Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States of America
- Center for Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, TN, United States of America
- James H Quillen Veterans Affairs Medical Center, Mountain Home, TN, United States of America
- * E-mail:
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35
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Wang Y, Wang B, Li P, Zhang Q, Liu P. Reduced RAC1 activity inhibits cell proliferation and induces apoptosis in neurofibromatosis type 2(NF2)-associated schwannoma. Neurol Res 2017; 39:1086-1093. [PMID: 28934903 DOI: 10.1080/01616412.2017.1376494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Objective To study the function and potential mechanism of RAC1 inhibitors in NF2-associated schwannoma. Methods In this study, we the downregulation of RAC1 activity and tumor cell phenotypes by RAC1 inhibitor NSC23766 in vitro. And we further validated the anti-proliferation effect by this RAC1 inhibitor in subcutaneous xenograft tumor model and sciatic nerve model. Results Pharmacological inhibition of RAC1 could significantly inhibit the proliferation of both RT4 cells and human NF2-associated primary schwannoma cells by inducing apoptosis. Pharmacological inhibition of RAC1 effectively reduced Rac1 activity and down-regulated the pathway downstream of Rac. Moreover, pharmacological inhibition of RAC1 showed a potential antitumor effect, with low toxicity in vivo. Conclusion RAC1 inhibitors may play a therapeutic role in patients with schwannoma.
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Affiliation(s)
- Ying Wang
- a Beijing Neurosurgical Institute, Capital Medical University , Beijing , China
| | - Bo Wang
- b Department of Neurosurgery , Beijing Tiantan Hospital, Capital Medical University , Beijing , China
| | - Peng Li
- b Department of Neurosurgery , Beijing Tiantan Hospital, Capital Medical University , Beijing , China
| | - Qi Zhang
- a Beijing Neurosurgical Institute, Capital Medical University , Beijing , China
| | - Pinan Liu
- a Beijing Neurosurgical Institute, Capital Medical University , Beijing , China.,b Department of Neurosurgery , Beijing Tiantan Hospital, Capital Medical University , Beijing , China
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36
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Ghidinelli M, Poitelon Y, Shin YK, Ameroso D, Williamson C, Ferri C, Pellegatta M, Espino K, Mogha A, Monk K, Podini P, Taveggia C, Nave KA, Wrabetz L, Park HT, Feltri ML. Laminin 211 inhibits protein kinase A in Schwann cells to modulate neuregulin 1 type III-driven myelination. PLoS Biol 2017. [PMID: 28636612 PMCID: PMC5479503 DOI: 10.1371/journal.pbio.2001408] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Myelin is required for proper nervous system function. Schwann cells in developing nerves depend on extrinsic signals from the axon and from the extracellular matrix to first sort and ensheathe a single axon and then myelinate it. Neuregulin 1 type III (Nrg1III) and laminin α2β1γ1 (Lm211) are the key axonal and matrix signals, respectively, but how their signaling is integrated and if each molecule controls both axonal sorting and myelination is unclear. Here, we use a series of epistasis experiments to show that Lm211 modulates neuregulin signaling to ensure the correct timing and amount of myelination. Lm211 can inhibit Nrg1III by limiting protein kinase A (PKA) activation, which is required to initiate myelination. We provide evidence that excessive PKA activation amplifies promyelinating signals downstream of neuregulin, including direct activation of the neuregulin receptor ErbB2 and its effector Grb2-Associated Binder-1 (Gab1), thereby elevating the expression of the key transcription factors Oct6 and early growth response protein 2 (Egr2). The inhibitory effect of Lm211 is seen only in fibers of small caliber. These data may explain why hereditary neuropathies associated with decreased laminin function are characterized by focally thick and redundant myelin.
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Affiliation(s)
- Monica Ghidinelli
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milano, Italy
- UniSR, Vita Salute San Raffaele University, Milan, Italy
| | - Yannick Poitelon
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Yoon Kyoung Shin
- Department of Physiology, Peripheral Neuropathy Research Center, Dong-A University Medical School, Busan, South Korea
| | - Dominique Ameroso
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Courtney Williamson
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Cinzia Ferri
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milano, Italy
| | - Marta Pellegatta
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milano, Italy
- UniSR, Vita Salute San Raffaele University, Milan, Italy
| | - Kevin Espino
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Amit Mogha
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kelly Monk
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Paola Podini
- Division of Neuroscience and INSPE, San Raffaele Scientific Institute, DIBIT, Milano, Italy
| | - Carla Taveggia
- Division of Neuroscience and INSPE, San Raffaele Scientific Institute, DIBIT, Milano, Italy
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Lawrence Wrabetz
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milano, Italy
| | - Hwan Tae Park
- Department of Physiology, Peripheral Neuropathy Research Center, Dong-A University Medical School, Busan, South Korea
- * E-mail: (MLF); (HTP)
| | - Maria Laura Feltri
- Hunter James Kelly Research Institute, Department of Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York at Buffalo, Buffalo, New York, United States of America
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milano, Italy
- * E-mail: (MLF); (HTP)
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Castelnovo LF, Bonalume V, Melfi S, Ballabio M, Colleoni D, Magnaghi V. Schwann cell development, maturation and regeneration: a focus on classic and emerging intracellular signaling pathways. Neural Regen Res 2017; 12:1013-1023. [PMID: 28852375 PMCID: PMC5558472 DOI: 10.4103/1673-5374.211172] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The development, maturation and regeneration of Schwann cells (SCs), the main glial cells of the peripheral nervous system, require the coordinate and complementary interaction among several factors, signals and intracellular pathways. These regulatory molecules consist of integrins, neuregulins, growth factors, hormones, neurotransmitters, as well as entire intracellular pathways including protein-kinase A, C, Akt, Erk/MAPK, Hippo, mTOR, etc. For instance, Hippo pathway is overall involved in proliferation, apoptosis, regeneration and organ size control, being crucial in cancer proliferation process. In SCs, Hippo is linked to merlin and YAP/TAZ signaling and it seems to respond to mechanic/physical challenges. Recently, among factors regulating SCs, also the signaling intermediates Src tyrosine kinase and focal adhesion kinase (FAK) proved relevant for SC fate, participating in the regulation of adhesion, motility, migration and in vitro myelination. In SCs, the factors Src and FAK are regulated by the neuroactive steroid allopregnanolone, thus corroborating the importance of this steroid in the control of SC maturation. In this review, we illustrate some old and novel signaling pathways modulating SC biology and functions during the different developmental, mature and regenerative states.
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Affiliation(s)
- Luca Franco Castelnovo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Veronica Bonalume
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Simona Melfi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Marinella Ballabio
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Deborah Colleoni
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Valerio Magnaghi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
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Shi Y, Bollam SR, White SM, Laughlin SZ, Graham GT, Wadhwa M, Chen H, Nguyen C, Vitte J, Giovannini M, Toretsky J, Yi C. Rac1-Mediated DNA Damage and Inflammation Promote Nf2 Tumorigenesis but Also Limit Cell-Cycle Progression. Dev Cell 2016; 39:452-465. [PMID: 27818180 PMCID: PMC5519326 DOI: 10.1016/j.devcel.2016.09.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/09/2016] [Accepted: 09/27/2016] [Indexed: 01/04/2023]
Abstract
Merlin encoded by the Nf2 gene is a bona fide tumor suppressor that has been implicated in regulation of both the Hippo-Yap and Rac1-Pak1 pathways. Using genetically engineered murine liver models, we show that co-deletion of Rac1 with Nf2 blocks tumor initiation but paradoxically exacerbates hepatomegaly induced by Nf2 loss, which can be suppressed either by treatment with pro-oxidants or by co-deletion of Yap. Our results suggest that while Yap acts as the central driver of proliferation during Nf2 tumorigenesis, Rac1 primarily functions as an inflammation switch by inducing reactive oxygen species that, on one hand, induce nuclear factor κB signaling and expression of inflammatory cytokines, and on the other activate p53 checkpoint and senescence programs dampening the cyclin D1-pRb-E2F1 pathway. Interestingly, senescence markers are associated with benign NF2 tumors but not with malignant NF2 mutant mesotheliomas, suggesting that senescence may underlie the benign nature of most NF2 tumors.
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Affiliation(s)
- Yuhao Shi
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Saumya R Bollam
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Shannon M White
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Sean Z Laughlin
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Garrett T Graham
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Mandheer Wadhwa
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Hengye Chen
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Chan Nguyen
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Jeremie Vitte
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Marco Giovannini
- Department of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Jeffery Toretsky
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Chunling Yi
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA.
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39
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Fu X, Tong Z, Li Q, Niu Q, Zhang Z, Tong X, Tong L, Zhang X. Induction of adipose-derived stem cells into Schwann-like cells and observation of Schwann-like cell proliferation. Mol Med Rep 2016; 14:1187-93. [PMID: 27279556 PMCID: PMC4940092 DOI: 10.3892/mmr.2016.5367] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 05/21/2016] [Indexed: 01/05/2023] Open
Abstract
The peripheral nervous system has the potential for full regeneration following injury and recovery, predominantly controlled by Schwann cells (SCs). Therefore, obtaining a sufficient number of SCs in a short duration is crucial. In the present study, rat adipose-derived stem cells (ADSCs) were isolated and cultured, following which characterization of the ADSCs was performed using flow cytometry. The results showed that the cells were positive for the CD29 and CD44 markers, and negative for the CD31, CD45, CD49 and CD106 markers. The multilineage differentiation potential of the ADSCs was assayed by determining the ability of the cells to differentiate into osteoblasts and adipocytes. Following this, the ADSCs were treated with a specific medium and differentiated into Schwann-like cells. Immunofluorescence, western blot and reverse transcription-quantitative polymerase chain reaction analyses showed that ~95% of the differentiated cells expressed glial fibrillary acidic protein, S100 and p75. In addition, the present study found that a substantial number of SCs can be produced in a short duration via the mitotic feature of Schwann-like cells. These data indicated that Schwann-like cells derived from ADSCs can undergo mitotic proliferation, which may be beneficial for the treatment of peripheral nerve injury in the future.
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Affiliation(s)
- Xiumei Fu
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zhaoxue Tong
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Qi Li
- Department of Hand Surgery, Affiliated Feng Tian Hospital, Shenyang Medical College, Shenyang, Liaoning 110001, P.R. China
| | - Qingfei Niu
- Department of Hand Surgery, Affiliated Feng Tian Hospital, Shenyang Medical College, Shenyang, Liaoning 110001, P.R. China
| | - Zhe Zhang
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xiaojie Tong
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Lei Tong
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xu Zhang
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning 110001, P.R. China
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40
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Lentivirus-Mediated RNA Interference Targeting RhoA Slacks the Migration, Proliferation, and Myelin Formation of Schwann Cells. Mol Neurobiol 2016; 54:1229-1239. [DOI: 10.1007/s12035-016-9733-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 01/19/2016] [Indexed: 10/24/2022]
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41
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Monk KR, Feltri ML, Taveggia C. New insights on Schwann cell development. Glia 2015; 63:1376-93. [PMID: 25921593 PMCID: PMC4470834 DOI: 10.1002/glia.22852] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/13/2015] [Indexed: 12/11/2022]
Abstract
In the peripheral nervous system, Schwann cells are glial cells that are in intimate contact with axons throughout development. Schwann cells generate the insulating myelin sheath and provide vital trophic support to the neurons that they ensheathe. Schwann cell precursors arise from neural crest progenitor cells, and a highly ordered developmental sequence controls the progression of these cells to become mature myelinating or nonmyelinating Schwann cells. Here, we discuss both seminal discoveries and recent advances in our understanding of the molecular mechanisms that drive Schwann cell development and myelination with a focus on cell-cell and cell-matrix signaling events.
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Affiliation(s)
- Kelly R Monk
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri
| | - M Laura Feltri
- Department of Biochemistry and Neurology, Hunter James Kelly Research Institute, University at Buffalo, State University of New York, Buffalo, New York
| | - Carla Taveggia
- Division of Neuroscience and INSPE, San Raffaele Scientific Institute, Milan, Italy
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42
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Ahmad I, Fernando A, Gurgel R, Jason Clark J, Xu L, Hansen MR. Merlin status regulates p75(NTR) expression and apoptotic signaling in Schwann cells following nerve injury. Neurobiol Dis 2015; 82:114-122. [PMID: 26057084 DOI: 10.1016/j.nbd.2015.05.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 05/28/2015] [Accepted: 05/29/2015] [Indexed: 02/06/2023] Open
Abstract
After nerve injury, Schwann cells (SCs) dedifferentiate, proliferate, and support axon regrowth. If axons fail to regenerate, denervated SCs eventually undergo apoptosis due, in part, to increased expression of the low-affinity neurotrophin receptor, p75(NTR). Merlin is the protein product of the NF2 tumor suppressor gene implicated in SC tumorigenesis. Here we explore the contribution of merlin to SC responses to nerve injury. We find that merlin becomes phosphorylated (growth permissive) in SCs following acute axotomy and following gradual neural degeneration in a deafness model, temporally correlated with increased p75(NTR) expression. p75(NTR) levels are elevated in P0SchΔ39-121 transgenic mice that harbor an Nf2 mutation in SCs relative to wild-type mice before axotomy and remain elevated for a longer period of time following injury. Replacement of wild-type, but not phospho-mimetic (S518D), merlin isoforms suppresses p75(NTR) expression in primary human schwannoma cultures which otherwise lack functional merlin. Despite elevated levels of p75(NTR), SC apoptosis following axotomy is blunted in P0SchΔ39-121 mice relative to wild-type mice suggesting that loss of functional merlin contributes to SC resistance to apoptosis. Further, cultured SCs from mice with a tamoxifen-inducible knock-out of Nf2 confirm that SCs lacking functional merlin are less sensitive to p75(NTR)-mediated cell death. Taken together these results point to a model whereby loss of axonal contact following nerve injury results in merlin phosphorylation leading to increased p75(NTR) expression. Further, they demonstrate that merlin facilitates p75(NTR)-mediated apoptosis in SCs helping to explain how neoplastic SCs that lack functional merlin survive long-term in the absence of axonal contact.
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Affiliation(s)
- Iram Ahmad
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Augusta Fernando
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Richard Gurgel
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - J Jason Clark
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Linjing Xu
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Department of Neurosurgery, University of Iowa, Iowa City, IA 52242, USA.
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43
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A molecular mechanotransduction pathway regulates collective migration of epithelial cells. Nat Cell Biol 2015; 17:276-87. [DOI: 10.1038/ncb3115] [Citation(s) in RCA: 264] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 01/16/2015] [Indexed: 12/15/2022]
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44
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Bacallao K, Monje PV. Requirement of cAMP signaling for Schwann cell differentiation restricts the onset of myelination. PLoS One 2015; 10:e0116948. [PMID: 25705874 PMCID: PMC4338006 DOI: 10.1371/journal.pone.0116948] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 12/17/2014] [Indexed: 12/25/2022] Open
Abstract
Isolated Schwann cells (SCs) respond to cAMP elevation by adopting a differentiated post-mitotic state that exhibits high levels of Krox-20, a transcriptional enhancer of myelination, and mature SC markers such as the myelin lipid galactocerebroside (O1). To address how cAMP controls myelination, we performed a series of cell culture experiments which compared the differentiating responses of isolated and axon-related SCs to cAMP analogs and ascorbate, a known inducer of axon ensheathment, basal lamina formation and myelination. In axon-related SCs, cAMP induced the expression of Krox-20 and O1 without a concomitant increase in the expression of myelin basic protein (MBP) and without promoting axon ensheathment, collagen synthesis or basal lamina assembly. When cAMP was provided together with ascorbate, a dramatic enhancement of MBP expression occurred, indicating that cAMP primes SCs to form myelin only under conditions supportive of basal lamina formation. Experiments using a combination of cell permeable cAMP analogs and type-selective adenylyl cyclase (AC) agonists and antagonists revealed that selective transmembrane AC (tmAC) activation with forskolin was not sufficient for full SC differentiation and that the attainment of an O1 positive state also relied on the activity of the soluble AC (sAC), a bicarbonate sensor that is insensitive to forskolin and GPCR activation. Pharmacological and immunological evidence indicated that SCs expressed sAC and that sAC activity was required for morphological differentiation and the expression of myelin markers such as O1 and protein zero. To conclude, our data indicates that cAMP did not directly drive myelination but rather the transition into an O1 positive state, which is perhaps the most critical cAMP-dependent rate limiting step for the onset of myelination. The temporally restricted role of cAMP in inducing differentiation independently of basal lamina formation provides a clear example of the uncoupling of signals controlling differentiation and myelination in SCs.
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Affiliation(s)
- Ketty Bacallao
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Paula V. Monje
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- * E-mail:
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45
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Abstract
Peripheral nerves contain large myelinated and small unmyelinated (Remak) fibers that perform different functions. The choice to myelinate or not is dictated to Schwann cells by the axon itself, based on the amount of neuregulin I-type III exposed on its membrane. Peripheral axons are more important in determining the final myelination fate than central axons, and the implications for this difference in Schwann cells and oligodendrocytes are discussed. Interestingly, this choice is reversible during pathology, accounting for the remarkable plasticity of Schwann cells, and contributing to the regenerative potential of the peripheral nervous system. Radial sorting is the process by which Schwann cells choose larger axons to myelinate during development. This crucial morphogenetic step is a prerequisite for myelination and for differentiation of Remak fibers, and is arrested in human diseases due to mutations in genes coding for extracellular matrix and linkage molecules. In this review we will summarize progresses made in the last years by a flurry of reverse genetic experiments in mice and fish. This work revealed novel molecules that control radial sorting, and contributed unexpected ideas to our understanding of the cellular and molecular mechanisms that control radial sorting of axons.
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Affiliation(s)
- M Laura Feltri
- Hunter James Kelly Research Institute, Departments of Biochemistry & Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Yannick Poitelon
- Hunter James Kelly Research Institute, Departments of Biochemistry & Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Stefano Carlo Previtali
- Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
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46
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Nobbio L, Visigalli D, Mannino E, Fiorese F, Kassack MU, Sturla L, Prada V, De Flora A, Zocchi E, Bruzzone S, Schenone A. The diadenosine homodinucleotide P18 improves in vitro myelination in experimental Charcot-Marie-Tooth type 1A. J Cell Biochem 2014; 115:161-7. [PMID: 23959806 DOI: 10.1002/jcb.24644] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/02/2013] [Indexed: 11/05/2022]
Abstract
Charcot-Marie-Tooth 1A (CMT1A) is a demyelinating hereditary neuropathy whose pathogenetic mechanisms are still poorly defined and an etiologic treatment is not yet available. An abnormally high intracellular Ca(2+) concentration ([Ca(2+)]i) occurs in Schwann cells from CMT1A rats (CMT1A SC) and is caused by overexpression of the purinoceptor P2X7. Normalization of the Ca(2+) levels through down-regulation of P2X7 appears to restore the normal phenotype of CMT1A SC in vitro. We recently demonstrated that the diadenosine 5',5'''-P1, P2-diphosphate (Ap2A) isomer P18 behaves as an antagonist of the P2X7 purinergic receptor, effectively blocking channel opening induced by ATP. In addition, P18 behaves as a P2Y11 agonist, inducing cAMP overproduction in P2Y11-overexpressing cells. Here we investigated the in vitro effects of P18 on CMT1A SC. We observed that basal levels of intracellular cAMP ([cAMP]i), a known regulator of SC differentiation and myelination, are significantly lower in CMT1A SC than in wild-type (wt) cells. P18 increased [cAMP]i in both CMT1A and wt SC, and this effects was blunted by NF157, a specific P2Y11 antagonist. Prolonged treatment of organotypic dorsal root ganglia (DRG) cultures with P18 significantly increased expression of myelin protein zero, a marker of myelin production, in both CMT1A and wt cultures. Interestingly, P18 decreased the content of non-phosphorylated neurofilaments, a marker of axonal damage, only in CMT1A DRG cultures. These results suggest that P2X7 antagonists, in combination with [cAMP]i-increasing agents, could represent a therapeutic strategy aimed at correcting the molecular derangements causing the CMT1A phenotype.
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Affiliation(s)
- Lucilla Nobbio
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics and Mother and Child Sciences and CEBR, University of Genova, Genova, Italy
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47
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Garcia C, Gutmann DH. Using the neurofibromatosis tumor predisposition syndromes to understand normal nervous system development. SCIENTIFICA 2014; 2014:915725. [PMID: 25243094 PMCID: PMC4163293 DOI: 10.1155/2014/915725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
Abstract
Development is a tightly regulated process that involves stem cell self-renewal, differentiation, cell-to-cell communication, apoptosis, and blood vessel formation. These coordinated processes ensure that tissues maintain a size and architecture that is appropriate for normal tissue function. As such, tumors arise when cells acquire genetic mutations that allow them to escape the normal growth constraints. In this regard, the study of tumor predisposition syndromes affords a unique platform to better understand normal development and the process by which normal cells transform into cancers. Herein, we review the processes governing normal brain development, discuss how brain cancer represents a disruption of these normal processes, and highlight insights into both normal development and cancer made possible by the study of tumor predisposition syndromes.
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Affiliation(s)
- Cynthia Garcia
- Department of Neurology, Washington University School of Medicine, Box 8111, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - David H. Gutmann
- Department of Neurology, Washington University School of Medicine, Box 8111, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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48
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Patra C, Monk KR, Engel FB. The multiple signaling modalities of adhesion G protein-coupled receptor GPR126 in development. ACTA ACUST UNITED AC 2014; 1:79. [PMID: 25493288 DOI: 10.14800/rci.79] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The G protein-coupled receptor (GPCR) superfamily is the largest known receptor family in the human genome. Although the family of adhesion GPCRs comprises the second largest sub-family, their function is poorly understood. Here, we review the current knowledge about the adhesion GPCR family member GPR126. GPR126 possesses a signal peptide, a 7TM domain homologous to secretin-like GPCRs, a GPS motif and an extended N-terminus containing a CUB (Complement, Uegf, Bmp1) domain, a PTX (Pentraxin) domain, a hormone binding domain and 27 putative N-glycosylation sites. Knockdown and knockout experiments in zebrafish and mice have demonstrated that Gpr126 plays an essential role in neural, cardiac and ear development. In addition, genome-wide association studies have implicated variations at the GPR126 locus in obstructive pulmonary dysfunction, in scoliosis and as a determinant of trunk length and body height. Gpr126 appears to exert its function depending on the organ system via G protein- and/or N-terminus-dependent signaling. Here, we review the current knowledge about Gpr126, which, due to the variety of its functions and its multiple signaling modalities, provides a model adhesion GPCR to understand general functional concepts utilized by adhesion GPCRs.
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Affiliation(s)
- Chinmoy Patra
- Department of Developmental Genetics, Max-Planck-Institute for Heart and Lung Research, Ludwigstrasse 43, 61231 Bad Nauheim, Germany
| | - Kelly R Monk
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Ave, St. Louis, MO 63110, USA
| | - Felix B Engel
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Universitätsstraße 22, 91054 Erlangen, Germany
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49
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Abstract
During development, Schwann cells extend lamellipodia-like processes to segregate large- and small-caliber axons during the process of radial sorting. Radial sorting is a prerequisite for myelination and is arrested in human neuropathies because of laminin deficiency. Experiments in mice using targeted mutagenesis have confirmed that laminins 211, 411, and receptors containing the β1 integrin subunit are required for radial sorting; however, which of the 11 α integrins that can pair with β1 forms the functional receptor is unknown. Here we conditionally deleted all the α subunits that form predominant laminin-binding β1 integrins in Schwann cells and show that only α6β1 and α7β1 integrins are required and that α7β1 compensates for the absence of α6β1 during development. The absence of either α7β1 or α6β1 integrin impairs the ability of Schwann cells to spread and to bind laminin 211 or 411, potentially explaining the failure to extend cytoplasmic processes around axons to sort them. However, double α6/α7 integrin mutants show only a subset of the abnormalities found in mutants lacking all β1 integrins, and a milder phenotype. Double-mutant Schwann cells can properly activate all the major signaling pathways associated with radial sorting and show normal Schwann cell proliferation and survival. Thus, α6β1 and α7β1 are the laminin-binding integrins required for axonal sorting, but other Schwann cell β1 integrins, possibly those that do not bind laminins, may also contribute to radial sorting during peripheral nerve development.
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Gpr126 functions in Schwann cells to control differentiation and myelination via G-protein activation. J Neurosci 2014; 33:17976-85. [PMID: 24227709 DOI: 10.1523/jneurosci.1809-13.2013] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The myelin sheath surrounding axons ensures that nerve impulses travel quickly and efficiently, allowing for the proper function of the vertebrate nervous system. We previously showed that the adhesion G-protein-coupled receptor (aGPCR) Gpr126 is essential for peripheral nervous system myelination, although the molecular mechanisms by which Gpr126 functions were incompletely understood. aGPCRs are a significantly understudied protein class, and it was unknown whether Gpr126 couples to G-proteins. Here, we analyze Dhh(Cre);Gpr126(fl/fl) conditional mutants, and show that Gpr126 functions in Schwann cells (SCs) for radial sorting of axons and myelination. Furthermore, we demonstrate that elevation of cAMP levels or protein kinase A activation suppresses myelin defects in Gpr126 mouse mutants and that cAMP levels are reduced in conditional Gpr126 mutant peripheral nerve. Finally, we show that GPR126 directly increases cAMP by coupling to heterotrimeric G-proteins. Together, these data support a model in which Gpr126 functions in SCs for proper development and myelination and provide evidence that these functions are mediated via G-protein-signaling pathways.
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