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Montani L, Buerki-Thurnherr T, de Faria JP, Pereira JA, Dias NG, Fernandes R, Gonçalves AF, Braun A, Benninger Y, Böttcher RT, Costell M, Nave KA, Franklin RJM, Meijer D, Suter U, Relvas JB. Profilin 1 is required for peripheral nervous system myelination. Development 2014; 141:1553-61. [PMID: 24598164 DOI: 10.1242/dev.101840] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Myelination allows rapid saltatory propagation of action potentials along the axon and is an essential prerequisite for the normal functioning of the nervous system. During peripheral nervous system (PNS) development, myelin-forming Schwann cells (SCs) generate radial lamellipodia to sort and ensheath axons. This process requires controlled cytoskeletal remodeling, and we show that SC lamellipodia formation depends on the function of profilin 1 (Pfn1), an actin-binding protein involved in microfilament polymerization. Pfn1 is inhibited upon phosphorylation by ROCK, a downstream effector of the integrin linked kinase pathway. Thus, a dramatic reduction of radial lamellipodia formation is observed in SCs lacking integrin-linked kinase or treated with the Rho/ROCK activator lysophosphatidic acid. Knocking down Pfn1 expression by lentiviral-mediated shRNA delivery impairs SC lamellipodia formation in vitro, suggesting a direct role for this protein in PNS myelination. Indeed, SC-specific gene ablation of Pfn1 in mice led to profound radial sorting and myelination defects, confirming a central role for this protein in PNS development. Our data identify Pfn1 as a key effector of the integrin linked kinase/Rho/ROCK pathway. This pathway, acting in parallel with integrin β1/LCK/Rac1 and their effectors critically regulates SC lamellipodia formation, radial sorting and myelination during peripheral nervous system maturation.
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Affiliation(s)
- Laura Montani
- Instituto de Biologia Molecular e Celular, 4150-180 Porto, Portugal
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Pereira JA, Benninger Y, Baumann R, Gonçalves AF, Ozçelik M, Thurnherr T, Tricaud N, Meijer D, Fässler R, Suter U, Relvas JB. Integrin-linked kinase is required for radial sorting of axons and Schwann cell remyelination in the peripheral nervous system. ACTA ACUST UNITED AC 2009; 185:147-61. [PMID: 19349584 PMCID: PMC2700520 DOI: 10.1083/jcb.200809008] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
During development, Schwann cells (SCs) interpret different extracellular cues to regulate their migration, proliferation, and the remarkable morphological changes associated with the sorting, ensheathment, and myelination of axons. Although interactions between extracellular matrix proteins and integrins are critical to some of these processes, the downstream signaling pathways they control are still poorly understood. Integrin-linked kinase (ILK) is a focal adhesion protein that associates with multiple binding partners to link integrins to the actin cytoskeleton and is thought to participate in integrin and growth factor–mediated signaling. Using SC-specific gene ablation, we report essential functions for ILK in radial sorting of axon bundles and in remyelination in the peripheral nervous system. Our in vivo and in vitro experiments show that ILK negatively regulates Rho/Rho kinase signaling to promote SC process extension and to initiate radial sorting. ILK also facilitates axon remyelination, likely by promoting the activation of downstream molecules such as AKT/protein kinase B.
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Affiliation(s)
- Jorge A Pereira
- Institute of Cell Biology, Department of Biology, Eidgenössische Technische Hochschule Zurich, Zurich, Switzerland
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Benninger Y, Thurnherr T, Pereira JA, Krause S, Wu X, Chrostek-Grashoff A, Herzog D, Nave KA, Franklin RJM, Meijer D, Brakebusch C, Suter U, Relvas JB. Essential and distinct roles for cdc42 and rac1 in the regulation of Schwann cell biology during peripheral nervous system development. ACTA ACUST UNITED AC 2007; 177:1051-61. [PMID: 17576798 PMCID: PMC2064365 DOI: 10.1083/jcb.200610108] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
During peripheral nervous system (PNS) myelination, Schwann cells must interpret extracellular cues to sense their environment and regulate their intrinsic developmental program accordingly. The pathways and mechanisms involved in this process are only partially understood. We use tissue-specific conditional gene targeting to show that members of the Rho GTPases, cdc42 and rac1, have different and essential roles in axon sorting by Schwann cells. Our results indicate that although cdc42 is required for normal Schwann cell proliferation, rac1 regulates Schwann cell process extension and stabilization, allowing efficient radial sorting of axon bundles.
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Affiliation(s)
- Yves Benninger
- Institute of Cell Biology, Department of Biology, Eidgenössische Technische Hochschule Zurich, CH-8093 Zurich, Switzerland
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Thurnherr T, Benninger Y, Wu X, Chrostek A, Krause SM, Nave KA, Franklin RJM, Brakebusch C, Suter U, Relvas JB. Cdc42 and Rac1 signaling are both required for and act synergistically in the correct formation of myelin sheaths in the CNS. J Neurosci 2006; 26:10110-9. [PMID: 17021167 PMCID: PMC6674638 DOI: 10.1523/jneurosci.2158-06.2006] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The formation of myelin sheaths in the CNS is the result of a complex series of events involving oligodendrocyte progenitor cell (OPC) proliferation, directed migration, and the morphological changes associated with axon ensheathment and myelination. To examine the role of Rho GTPases in oligodendrocyte biology, we have used a conditional tissue-specific gene-targeting approach. Ablation of Cdc42 in cells of the oligodendrocyte lineage did not affect OPC proliferation, directed migration, or in vitro differentiation, but it led to the formation of a unique and stage-specific myelination phenotype. This was characterized by the extraordinary enlargement of the inner tongue of the oligodendrocyte process and concomitant formation of a myelin outfolding as a result of abnormal accumulation of cytoplasm in this region. Ablation of Rac1 also resulted in the abnormal accumulation of cytoplasm in the inner tongue of the oligodendrocyte process, and we provide genetic evidence that rac1 synergizes with cdc42 in a gene dosage-dependent way to regulate myelination.
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Affiliation(s)
- Tina Thurnherr
- Institute for Cell Biology, Department of Biology, Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland
| | - Yves Benninger
- Institute for Cell Biology, Department of Biology, Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland
| | - Xunwei Wu
- Department of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Anna Chrostek
- Department of Molecular Medicine, Max Planck Institute for Biochemistry, D-82152 Martinsried, Germany
| | - Sven M. Krause
- Institute for Cell Biology, Department of Biology, Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Goettingen, Germany, and
| | - Robin J. M. Franklin
- Cambridge Centre for Brain Repair and Neuroregeneration Laboratory, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, United Kingdom
| | - Cord Brakebusch
- Department of Molecular Pathology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ueli Suter
- Institute for Cell Biology, Department of Biology, Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland
| | - João B. Relvas
- Institute for Cell Biology, Department of Biology, Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland
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Benninger Y, Colognato H, Thurnherr T, Franklin RJM, Leone DP, Atanasoski S, Nave KA, ffrench-Constant C, Suter U, Relvas JB. Beta1-integrin signaling mediates premyelinating oligodendrocyte survival but is not required for CNS myelination and remyelination. J Neurosci 2006; 26:7665-73. [PMID: 16855094 PMCID: PMC6674273 DOI: 10.1523/jneurosci.0444-06.2006] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Previous reports, including transplantation experiments using dominant-negative inhibition of beta1-integrin signaling in oligodendrocyte progenitor cells, suggested that beta1-integrin signaling is required for myelination. Here, we test this hypothesis using conditional ablation of the beta1-integrin gene in oligodendroglial cells during the development of the CNS. This approach allowed us to study oligodendroglial beta1-integrin signaling in the physiological environment of the CNS, circumventing the potential drawbacks of a dominant-negative approach. We found that beta1-integrin signaling has a much more limited role than previously expected. Although it was involved in stage-specific oligodendrocyte cell survival, beta1-integrin signaling was not required for axon ensheathment and myelination per se. We also found that, in the spinal cord, remyelination occurred normally in the absence of beta1-integrin. We conclude that, although beta1-integrin may still contribute to other aspects of oligodendrocyte biology, it is not essential for myelination and remyelination in the CNS.
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Benninger Y, Marino S, Hardegger R, Weissmann C, Aguzzi A, Brandner S. Differentiation and histological analysis of embryonic stem cell-derived neural transplants in mice. Brain Pathol 2006; 10:330-41. [PMID: 10885652 PMCID: PMC8098556 DOI: 10.1111/j.1750-3639.2000.tb00265.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We report here that neural transplantation of in vitro-differentiated embryonic stem (ES) cells provides a versatile strategy for gene transfer into the central nervous system. ES cells were subjected to an optimized in vitro differentiation protocol to obtain embryoid bodies. These aggregates were stereotaxically transplanted into the brain of recipient adult mice, where they followed a strictly controlled differentiation pattern and eventually formed mature neural grafts. A marker gene, introduced into the ROSA26 locus allowed for precise determination of the fate of the descendants of the transplanted embryoid bodies and revealed that not only neurons but also astrocytes, oligodendrocytes and even microglial cells were graft-derived. Evaluation of long-term experiments showed viable grafts with a stable transgene expression and proved that this approach provides a tool for reliable gene expression within a spatially delimited area of neural tissue.
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Affiliation(s)
- Yves Benninger
- Institute of Neuropathology, University Hospital, Zurich, Switzerland
| | - Silvia Marino
- Division of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Roland Hardegger
- Institute of Neuropathology, University Hospital, Zurich, Switzerland
| | - Charles Weissmann
- Imperial College School of Medicine, Norfolk Place, London, United Kingdom
| | - Adriano Aguzzi
- Institute of Neuropathology, University Hospital, Zurich, Switzerland
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Raeber AJ, Brandner S, Klein MA, Benninger Y, Musahl C, Frigg R, Roeckl C, Fischer MB, Weissmann C, Aguzzi A. Transgenic and knockout mice in research on prion diseases. Brain Pathol 2006; 8:715-33. [PMID: 9804380 PMCID: PMC8098451 DOI: 10.1111/j.1750-3639.1998.tb00197.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Since the discovery of the prion protein (PrP) gene more than a decade ago, transgenetic investigations on the PrP gene have shaped the field of prion biology in an unprecedented way. Many questions regarding the role of PrP in susceptibility of an organism exposed to prions have been elucidated. For example mice with a targeted disruption of the PrP gene have allowed the demonstration that an organism that lacks PrPc is resistant to infection by prions. Reconstitution of these mice with mutant PrP genes allowed investigations on the structure-activity relationship of the PrP gene with regard to scrapie susceptibility. Unexpectedly, transgenic mice expressing PrP with specific amino-proximal truncations spontaneously develop a neurologic syndrome presenting with ataxia and cerebellar lesions. A distinct spontaneous neurologic phenotype was observed in mice with internal deletions in PrP. Using ectopic expression of PrP in PrP knockout mice has turned out to be a valuable approach towards the identification of host cells that are capable of replicating prions. Transgenic mice have also contributed to our understanding of the molecular basis of the species barrier for prions. Finally, the availability of PrP knockout mice and transgenic mice overexpressing PrP allows selective reconstitution experiments aimed at expressing PrP in neurografts or in specific populations of hemato- and lymphopoietic cells. Such studies have shed new light onto the mechanisms of prion spread and disease pathogenesis.
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Affiliation(s)
- A J Raeber
- Institute of Neuropathology, Department of Pathology, University Hospital, Zürich, Switzerland.
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