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Doutt SW, Longo JF, Carroll SL. LPAR1 and aberrantly expressed LPAR3 differentially promote the migration and proliferation of malignant peripheral nerve sheath tumor cells. Glia 2023; 71:742-757. [PMID: 36416236 PMCID: PMC9868101 DOI: 10.1002/glia.24308] [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: 04/13/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/24/2022]
Abstract
Schwann cell-derived neoplasms known as malignant peripheral nerve sheath tumors (MPNSTs) are the most common malignancy and the leading cause of death in individuals with neurofibromatosis Type 1. Using genome-scale shRNA screens, we have previously found evidence suggesting that lysophosphatidic acid receptors (LPARs) are essential for MPNST proliferation and/or survival. Here, we examine the expression and mutational status of all six LPA receptors in MPNSTs, assess the role that individual LPA receptors play in MPNST physiology and examine their ability to activate key neurofibromin-regulated signaling cascades. We found that human Schwann cells express LPAR1 and LPAR6, while MPNST cells express predominantly LPAR1 and LPAR3. Whole exome sequencing of 16 MPNST cell lines showed no evidence of mutations in any LPAR genes or ENPP2, a gene encoding a major LPA biosynthetic enzyme. Oleoyl-LPA, an LPA variant with an unsaturated side chain, promoted MPNST cell proliferation and migration. LPAR1 knockdown ablated the promigratory effect of LPA, while LPAR3 knockdown decreased proliferation. Inhibition of R-Ras signaling with a doxycycline-inducible dominant negative (DN) R-Ras mutant, which inhibits both R-Ras and R-Ras2, blocked LPA's promigratory effect. In contrast, DN R-Ras did not affect migration induced by neuregulin-1β (NRG1β), suggesting that LPA and NRG1β promote MPNST migration via distinct pathways. LPA-induced migration was also inhibited by Y27632, an inhibitor of the ROCK1/2 kinases that mediate R-Ras effects in MPNSTs. Thus, LPAR1 and aberrantly expressed LPAR3 mediate distinct effects in MPNSTs. These receptors and the signaling pathways that they regulate are potentially useful therapeutic targets in MPNSTs.
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Affiliation(s)
- Shannon Weber Doutt
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
- The Medical Scientist Training Program, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jody Fromm Longo
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Steven L Carroll
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
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2
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Chen SH, Kao HK, Wun JR, Chou PY, Chen ZY, Chen SH, Hsieh ST, Fang HW, Lin FH. Thermosensitive hydrogel carrying extracellular vesicles from adipose-derived stem cells promotes peripheral nerve regeneration after microsurgical repair. APL Bioeng 2022; 6:046103. [PMID: 36345317 PMCID: PMC9637024 DOI: 10.1063/5.0118862] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 10/02/2022] [Indexed: 11/06/2022] Open
Abstract
Peripheral nerve injuries are commonly occurring traumas of the extremities; functional recovery is hindered by slow nerve regeneration (<1 mm/day) following microsurgical repair and subsequent muscle atrophy. Functional recovery after peripheral nerve repair is highly dependent on local Schwann cell activity and axon regeneration speed. Herein, to promote nerve regeneration, paracrine signals of adipose-derived stem cells were applied in the form of extracellular vesicles (EVs) loaded in a thermosensitive hydrogel (PALDE) that could solidify rapidly and sustain high EV concentration around a repaired nerve during surgery. Cell experiments revealed that PALDE hydrogel markedly promotes Schwann-cell migration and proliferation and axon outgrowth. In a rat sciatic nerve repair model, the PALDE hydrogel increased repaired-nerve conduction efficacy; contraction force of leg muscles innervated by the repaired nerve also recovered. Electromicroscopic examination of downstream nerves indicated that fascicle diameter and myeline thickness in the PALDE group (1.91 ± 0.61 and 1.06 ± 0.40 μm, respectively) were significantly higher than those in PALD and control groups. Thus, this EV-loaded thermosensitive hydrogel is a potential cell-free therapeutic modality to improve peripheral-nerve regeneration, offering sustained and focused EV release around the nerve-injury site to overcome rapid clearance and maintain EV bioactivity in vivo.
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Affiliation(s)
- Shih-Heng Chen
- Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
- Department of Plastic and Reconstructive Surgery, Chang-Gung Memorial Hospital, Chang-Gung University and Medical College, Taoyuan, Taiwan
| | - Huang-Kai Kao
- Department of Plastic and Reconstructive Surgery, Chang-Gung Memorial Hospital, Chang-Gung University and Medical College, Taoyuan, Taiwan
| | - Jing-Ru Wun
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan
| | - Pang-Yun Chou
- Department of Plastic and Reconstructive Surgery, Chang-Gung Memorial Hospital, Chang-Gung University and Medical College, Taoyuan, Taiwan
| | - Zhi-Yu Chen
- Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
- Division of Biomedical Engineering and Nanomedicine Research, National Health Research Institutes, Miaoli, Taiwan
| | - Shih-Hsien Chen
- Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
- Department of Plastic and Reconstructive Surgery, Chang-Gung Memorial Hospital, Chang-Gung University and Medical College, Taoyuan, Taiwan
| | - Sung-Tsang Hsieh
- Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Hsu-Wei Fang
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan
- Division of Biomedical Engineering and Nanomedicine Research, National Health Research Institutes, Miaoli, Taiwan
| | - Feng-Huei Lin
- Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan
- Division of Biomedical Engineering and Nanomedicine Research, National Health Research Institutes, Miaoli, Taiwan
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KA-1002, a Novel Lysophosphatidic Acid Signaling Antagonist, Alleviates Bovine Tracheal Cell Disruption and Inflammation. Animals (Basel) 2020; 10:ani10020295. [PMID: 32069887 PMCID: PMC7070416 DOI: 10.3390/ani10020295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 02/08/2020] [Indexed: 12/23/2022] Open
Abstract
Abstract: The industrial livestock environment can cause stress and weakened immunity in cattle, leading to microbial infections which reduce productivity. As such, there is a need for an effective therapeutic agent that can alleviate uncontrolled destructive respiratory inflammation. We found that lysophosphatidic acid (LPA), a potent endogenous stress-induced inflammatory agent, causes respiratory tissue damage and triggers inflammation in bovine bronchial cells. LPA also inflames pulmonary bovine blood vessel cells to produce inflammatory cytokines. These findings strongly suggest that LPA is a highly important endogenous material exacerbating bovine respiratory diseases. We further identified a novel LPA-signaling antagonist, KA-1002, and showed that it alleviated LPA-mediated bovine tracheal cell disruption and inflammation. Therefore, KA-1002 could potentially serve as a novel therapeutic agent to maintain physiologically healthy and balanced conditions in bovine respiratory tracts.
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Montecchi-Palmer M, Bermudez JY, Webber HC, Patel GC, Clark AF, Mao W. TGFβ2 Induces the Formation of Cross-Linked Actin Networks (CLANs) in Human Trabecular Meshwork Cells Through the Smad and Non-Smad Dependent Pathways. Invest Ophthalmol Vis Sci 2017; 58:1288-1295. [PMID: 28241317 PMCID: PMC5341625 DOI: 10.1167/iovs.16-19672] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Purpose Increased intraocular pressure results from increased aqueous humor (AH) outflow resistance at the trabecular meshwork (TM) due to pathologic changes including the formation of cross-linked actin networks (CLANs). Transforming growth factor β2 (TGFβ2) is elevated in the AH and TM of primary open angle glaucoma (POAG) patients and induces POAG-associated TM changes, including CLANs. We determined the role of individual TGFβ2 signaling pathways in CLAN formation. Methods Cultured nonglaucomatous human TM (NTM) cells were treated with control or TGFβ2, with or without the inhibitors of TGFβ receptor, Smad3, c-Jun N-terminal kinases (JNK), extracellular signal regulated kinase (ERK), P38, or Rho-associated protein kinase (ROCK). NTM cells were cotreated with TGFβ2 plus inhibitors for 10 days or pretreated with TGFβ2 for 10 days followed by 1-hour inhibitor treatment. NTM cells were immunostained with phalloidin-Alexa-488 and 4',6-diamidino-2-phenylindole (DAPI). Data were analyzed using 1-way ANOVA and Dunnett's post hoc test. Results TGFβ2 significantly induced CLAN formation (n = 6 to 12, P < 0.05), which was completely inhibited by TGFβ receptor, Smad3, and ERK inhibitors, as well as completely or partially inhibited by JNK, P38, and ROCK inhibitors, depending on cell strains. One-hour exposure to ROCK inhibitor completely resolved formed CLANs (P < 0.05), whereas TGFβ receptor, Smad3 inhibitor, and ERK inhibitors resulted in partial or complete resolution. The JNK and P38 inhibitors showed partial or no resolution. Among these inhibitors, the ROCK inhibitor was the most disruptive to the actin stress fibers, whereas ERK inhibition showed the least disruption. Conclusions TGFβ2-induced CLANs in NTM cells were prevented and resolved using various pathway inhibitors. Apart from CLAN inhibition, some of these inhibitors also had different effects on actin stress fibers.
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Affiliation(s)
- Michela Montecchi-Palmer
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Jaclyn Y Bermudez
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Hannah C Webber
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Gaurang C Patel
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Weiming Mao
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
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Bermudez JY, Montecchi-Palmer M, Mao W, Clark AF. Cross-linked actin networks (CLANs) in glaucoma. Exp Eye Res 2017; 159:16-22. [PMID: 28238754 DOI: 10.1016/j.exer.2017.02.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/07/2016] [Accepted: 02/22/2017] [Indexed: 12/22/2022]
Abstract
One of the major causes of decreased vision, irreversible vision loss and blindness worldwide is glaucoma. Increased intraocular pressure (IOP) is a major risk factor associated with glaucoma and its molecular mechanisms are not fully understood. The trabecular meshwork (TM) is the primary site of injury in glaucoma, and its dysfunction results in elevated IOP. The glaucomatous TM has increased extracellular matrix deposition as well as cytoskeletal rearrangements referred to as cross-linked actin networks (CLANs) that consist of dome like structures consisting of hubs and spokes. CLANs are thought to play a role in increased aqueous humor outflow resistance and increased IOP by creating stiffer TM cells and tissue. CLANs are inducible by glucocorticoids (GCs) and TGFβ2 in confluent TM cells and TM tissues. The signaling pathways of these induction agents give insight into the possible mechanisms of CLAN formation, but to date, the mechanism of CLANs regulation by these pathways has yet to be determined. Understanding the role CLANs play in IOP elevation and their mechanisms of induction and regulation may lead to novel treatment options to help prevent or intervene in glaucomatous damage to the trabecular meshwork.
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Affiliation(s)
- Jaclyn Y Bermudez
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
| | - Michela Montecchi-Palmer
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
| | - Weiming Mao
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
| | - Abbot F Clark
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, United States.
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6
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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: 2.5] [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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7
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Pasten C, Cerda J, Jausoro I, Court FA, Cáceres A, Marzolo MP. ApoER2 and Reelin are expressed in regenerating peripheral nerve and regulate Schwann cell migration by activating the Rac1 GEF protein, Tiam1. Mol Cell Neurosci 2015; 69:1-11. [PMID: 26386179 DOI: 10.1016/j.mcn.2015.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/07/2015] [Indexed: 11/17/2022] Open
Abstract
ApoER2 and its ligand Reelin participate in neuronal migration during development. Upon receptor binding, Reelin induces the proteolytic processing of ApoER2 as well as the activation of signaling pathway, including small Rho GTPases. Besides its presence in the central nervous system (CNS), Reelin is also secreted by Schwann cells (SCs), the glial cells of the peripheral nervous system (PNS). Reelin deficient mice (reeler) show decreased axonal regeneration in the PNS; however neither the presence of ApoER2 nor the role of the Reelin signaling pathway in the PNS have been evaluated. Interestingly SC migration occurs during PNS development and during injury-induced regeneration and involves activation of small Rho GTPases. Thus, Reelin-ApoER2 might regulate SC migration during axon regeneration in the PNS. Here we demonstrate the presence of ApoER2 in PNS. After sciatic nerve injury Reelin was induced and its receptor ApoER2 was proteolytically processed. In vitro, SCs express both Reelin and ApoER2 and Reelin induces SC migration. To elucidate the molecular mechanism underlying Reelin-dependent SC migration, we examined the involvement of Rac1, a conspicuous small GTPase family member. FRET experiments revealed that Reelin activates Rac1 at the leading edge of SCs. In addition, Tiam1, a major Rac1-specific GEF was required for Reelin-induced SC migration. Moreover, Reelin-induced SC migration was decreased after suppression of the polarity protein PAR3, consistent with its association to Tiam1. Even more interesting, we demonstrated that PAR3 binds preferentially to the full-length cytoplasmic tail of ApoER2 corresponding to the splice-variant containing the exon 19 that encodes a proline-rich insert and that ApoER2 was required for SC migration. Our study reveals a novel function for Reelin/ApoER2 in PNS, inducing cell migration of SCs, a process relevant for PNS development and regeneration.
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Affiliation(s)
- Consuelo Pasten
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Millennium Nucleus for Regenerative Biology, Santiago, Chile
| | - Joaquín Cerda
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Millennium Nucleus for Regenerative Biology, Santiago, Chile
| | - Ignacio Jausoro
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Millennium Nucleus for Regenerative Biology, Santiago, Chile
| | - Felipe A Court
- Millennium Nucleus for Regenerative Biology, Santiago, Chile; Departmento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alfredo Cáceres
- Laboratory of Neurobiology, Instituto Mercedes y Martin Ferreyra (INIMEC) CONICET, Córdoba, Argentina
| | - Maria-Paz Marzolo
- Laboratorio de Tráfico Intracelular y Señalización, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Millennium Nucleus for Regenerative Biology, Santiago, Chile.
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8
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Fingolimod induces the transition to a nerve regeneration promoting Schwann cell phenotype. Exp Neurol 2015; 271:25-35. [PMID: 25957629 DOI: 10.1016/j.expneurol.2015.05.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/29/2015] [Accepted: 05/01/2015] [Indexed: 11/23/2022]
Abstract
Successful regeneration of injured peripheral nerves is mainly attributed to the plastic behavior of Schwann cells. Upon loss of axons, these cells trans-differentiate into regeneration promoting repair cells which provide trophic support to regrowing axons. Among others, activation of cJun was revealed to be involved in this process, initiating the stereotypic pattern of Schwann cell phenotype alterations during Wallerian degeneration. Nevertheless, the ability of Schwann cells to adapt and therefore the nerve's potential to regenerate can be limited in particular after long term denervation or in neuropathies leading to incomplete regeneration only and thus emphasizing the need for novel therapeutic approaches. Here we stimulated primary neonatal and adult rat Schwann cells with Fingolimod/FTY720P and investigated its impact on the regeneration promoting phenotype. FTY720P activated a number of de-differentiation markers including cJun and interfered with maturation marker and myelin expression. Functionally, FTY720P treated Schwann cells upregulated growth factor expression and these cells enhanced dorsal root ganglion neurite outgrowth on inhibitory substrates. Our results therefore provide strong evidence that FTY720P application supports the generation of a repair promoting cellular phenotype and suggest that Fingolimod could be used as treatment for peripheral nerve injuries and diseases.
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Filla MS, Clark R, Peters DM. A syndecan-4 binding peptide derived from laminin 5 uses a novel PKCε pathway to induce cross-linked actin network (CLAN) formation in human trabecular meshwork (HTM) cells. Exp Cell Res 2014; 327:171-82. [PMID: 25128150 PMCID: PMC4164596 DOI: 10.1016/j.yexcr.2014.07.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 07/17/2014] [Accepted: 07/22/2014] [Indexed: 12/31/2022]
Abstract
In this study, we examined the role(s) of syndecan-4 in regulating the formation of an actin geodesic dome structure called a cross-linked actin network (CLAN) in which syndecan-4 has previously been localized. CLANs have been described in several different cell types, but they have been most widely studied in human trabecular meshwork (HTM) cells where they may play a key role in controlling intraocular pressure by regulating aqueous humor outflow from the eye. In this study we show that a loss of cell surface synedcan-4 significantly reduces CLAN formation in HTM cells. Analysis of HTM cultures treated with or without dexamethasone shows that laminin 5 deposition within the extracellular matrix is increased by glucocorticoid treatment and that a laminin 5-derived, syndecan-4-binding peptide (PEP75), induces CLAN formation in TM cells. This PEP75-induced CLAN formation was inhibited by heparin and the broad spectrum PKC inhibitor Ro-31-7549. In contrast, the more specific PKCα inhibitor Gö 6976 had no effect, thus excluding PKCα as a downstream effector of syndecan-4 signaling. Analysis of PKC isozyme expression showed that HTM cells also expressed both PKCγ and PKCε. Cells treated with a PKCε agonist formed CLANs while a PKCα/γ agonist had no effect. These data suggest that syndecan-4 is essential for CLAN formation in HTM cells and that a novel PKCε-mediated signaling pathway can regulate formation of this unique actin structure.
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Affiliation(s)
- Mark S Filla
- Department of Ophthalmology & Visual Sciences, Medical Science Center, 1300 University Avenue, Madison, WI 53706, United States.
| | - Ross Clark
- Department of Pathology & Laboratory Medicine, Medical Science Center, 1300 University Avenue, Madison, WI 53706, United States.
| | - Donna M Peters
- Department of Ophthalmology & Visual Sciences, Medical Science Center, 1300 University Avenue, Madison, WI 53706, United States; Department of Pathology & Laboratory Medicine, Medical Science Center, 1300 University Avenue, Madison, WI 53706, United States.
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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] [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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11
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Procacci P, Ballabio M, Castelnovo LF, Mantovani C, Magnaghi V. GABA-B receptors in the PNS have a role in Schwann cells differentiation? Front Cell Neurosci 2013; 6:68. [PMID: 23335881 PMCID: PMC3541506 DOI: 10.3389/fncel.2012.00068] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 12/19/2012] [Indexed: 12/31/2022] Open
Abstract
γ-aminobutyric acid type B (GABA-B) receptor mediates the inhibitory transmission of γ-aminobutyric acid in the mammalian nervous system, being present in neurons and also in glial cells. Recently the presence of GABA-B has been demonstrated in Schwann cells (SC) suggesting its contribution in regulating the cell fate, maturation, and plasticity. Here, we further support the functional presence of GABA-B receptor in SC plasma membrane. By confocal microscopy immunofluorescence we provide evidences that GABA-B localization on the cell elongated processes correlates with the morphological changes occurring in the differentiated SC. In vivo most of the GABA-B receptors seem to be present in non-myelinating SC, which are committed to ensheath the nociceptive fibers. Therefore, we argue that GABA-B receptors do not control exclusively the in vivo differentiation yielding the myelinating SC, but are also fundamental in regulating the SC plasticity versus the non-myelinating state. Data from the literature and our recent findings corroborate the role of the GABAergic system and GABA-B receptors in the peripheral nervous system, opening new perspectives on the mechanisms controlling the differentiation of SC.
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Affiliation(s)
- Patrizia Procacci
- Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano Milan, Italy
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12
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Frisca F, Sabbadini RA, Goldshmit Y, Pébay A. Biological Effects of Lysophosphatidic Acid in the Nervous System. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY VOLUME 296 2012; 296:273-322. [DOI: 10.1016/b978-0-12-394307-1.00005-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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13
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Martiáñez T, Carrascal M, Lamarca A, Segura M, Durany N, Masgrau R, Abian J, Gella A. UTP affects the Schwannoma cell line proteome through P2Y receptors leading to cytoskeletal reorganisation. Proteomics 2011; 12:145-56. [PMID: 22065602 DOI: 10.1002/pmic.201100187] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 09/09/2011] [Accepted: 10/19/2011] [Indexed: 12/23/2022]
Abstract
Glial cells in the peripheral nervous system, such as Schwann cells, respond to nucleotides, which play an important role in axonal regeneration and myelination. Metabotropic P2Y receptor agonists are promising therapeutic molecules for peripheral neuropathies. Nevertheless, the proteomic mechanisms involved in nucleotide action on Schwann cells remain unknown. Here, we studied intracellular protein changes in RT4-D6P2T Schwann cells after treatment with nucleotides and Nucleo CMP Forte (CMPF), a nucleotide-based drug. After treatment with CMPF, 2-D DIGE revealed 11 differential gel spots, which were all upregulated. Among these, six different proteins were identified by MS. Some of these proteins are involved in actin remodelling (actin-related protein, Arp3), membrane vesicle transport (Rab GDP dissociation inhibitor β, Rab GDI), and the endoplasmic reticulum stress response (protein disulfide isomerase A3, PDI), which are hallmarks of a possible P2Y receptor signalling pathway. Expression of P2Y receptors in RT4-D6P2T cells was demonstrated by RT-PCR and a transient elevation of intracellular calcium measured in response to UTP. Actin reorganisation was visualized after UTP treatment using phalloidin-FITC staining and was blocked by the P2Y antagonist suramin, which also inhibited Arp3, Rab GDI, and PDI protein upregulation. Our data indicate that extracellular UTP interacts with Schwann P2Y receptors and activates molecular machinery that induces changes in the glial cell cytoskeleton.
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Affiliation(s)
- Tánia Martiáñez
- Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Josep Trueta s/n, Sant Cugat del Vallès, Spain
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14
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Blaho VA, Hla T. Regulation of mammalian physiology, development, and disease by the sphingosine 1-phosphate and lysophosphatidic acid receptors. Chem Rev 2011; 111:6299-320. [PMID: 21939239 PMCID: PMC3216694 DOI: 10.1021/cr200273u] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Victoria A. Blaho
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10065
| | - Timothy Hla
- Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10065
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15
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Xu B, Bhullar RP. Regulation of Rac1 and Cdc42 activation in thrombin- and collagen-stimulated CHRF-288-11 cells. Mol Cell Biochem 2011; 353:73-9. [DOI: 10.1007/s11010-011-0776-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 03/07/2011] [Indexed: 11/30/2022]
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16
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Affiliation(s)
- Hiroshi Ueda
- Division of Molecular Pharmacology and Neuroscience, Graduate School of Biomedical Sciences, Nagasaki University
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Kim HJ, Jung CG, Dukala D, Bae H, Kakazu R, Wollmann R, Soliven B. Fingolimod and related compounds in a spontaneous autoimmune polyneuropathy. J Neuroimmunol 2009; 214:93-100. [PMID: 19647880 DOI: 10.1016/j.jneuroim.2009.07.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Revised: 07/03/2009] [Accepted: 07/06/2009] [Indexed: 12/11/2022]
Abstract
We investigated potential therapeutic effects of sphingosine-1-phosphate (S1P) receptor modulators FTY720 (fingolimod) and selective S1P1 agonist SEW2871 on a spontaneous autoimmune polyneuropathy (SAP) when given orally at 7 mo (anticipated disease onset) for 4 weeks. Clinical severity, electrophysiologic and histological findings were ameliorated in mice treated with 1 mg/kg of FTY720. Subsequent studies showed that SEW2871 was also effective in halting the progression of SAP, which was accompanied by decreased proliferative and cytokine responses to myelin protein zero (P0), and an increase in regulatory T cells. We conclude that S1P receptor modulators may play a therapeutic role in autoimmune neuropathies.
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Affiliation(s)
- Hye-Jung Kim
- Department of Neurology, The University of Chicago, Chicago, IL 60637, United States
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18
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Filla MS, Schwinn MK, Sheibani N, Kaufman PL, Peters DM. Regulation of cross-linked actin network (CLAN) formation in human trabecular meshwork (HTM) cells by convergence of distinct beta1 and beta3 integrin pathways. Invest Ophthalmol Vis Sci 2009; 50:5723-31. [PMID: 19643963 DOI: 10.1167/iovs.08-3215] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
PURPOSE To determine the beta1/beta3 integrin-mediated pathways that regulate cross-linked actin network (CLAN) formation in human trabecular meshwork (HTM) cells. CLANs form in glaucomatous and steroid-treated TM cells, which may contribute to reducing outflow facility through the TM. METHODS Expression of CD47 (an alphavbeta3 integrin coreceptor/thrombospondin-1 receptor) and integrins alphavbeta3 and beta1 was assessed by FACS. CLANs were induced by plating cells on fibronectin (a beta1 integrin ligand) in the absence or presence of the beta3 integrin-activating mAb AP-5 and were identified by phalloidin labeling. The role of Src kinases, PI-3 kinase (PI-3K), Rac1, and CD47 was determined by incubating cells with the inhibitors PP2 and EPA (Src kinases), LY294002 (PI-3K), or NSC23766 (Rac1). Tiam1 and Trio siRNAs and dominant-negative Tiam1 were used to determine which Rac1-specific guanine nucleotide exchange factor was involved. The role of CD47 was determined using the thrombospondin-1-derived agonist peptide 4N1K and the CD47 function blocking antibody B6H12.2. RESULTS HTM cells expressed CD47 and integrins alphavbeta3 and beta1. beta3 Integrin or CD47 activation significantly increased CLAN formation over beta1 integrin-induced levels, whereas anti-CD47 mAb B6H12.2 inhibited this increase. PP2, NSC23766, and Trio siRNA decreased beta3-induced CLAN formation by 72%, 45%, and 67%, respectively, whereas LY294002 and dominant negative Tiam1 had no effect. LY294002 decreased beta1 integrin-mediated CLAN formation by 42%, and PP2 completely blocked it. CONCLUSIONS Distinct beta1 and alphavbeta3 integrin signaling pathways converge to enhance CLAN formation. beta1-Mediated CLAN formation was PI-3K dependent, whereas beta3-mediated CLAN formation was CD47 and Rac1/Trio dependent and might have been regulated by thrombospondin-1. Both integrin pathways were Src dependent.
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Affiliation(s)
- Mark S Filla
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA
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19
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Feltri ML, Suter U, Relvas JB. The function of RhoGTPases in axon ensheathment and myelination. Glia 2009; 56:1508-1517. [PMID: 18803320 DOI: 10.1002/glia.20752] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
RhoGTPases are molecular switches that integrate extracellular signals to perform diverse cellular responses. This ability relies on the network of proteins regulating RhoGTPases activity and localization, and on the interaction of RhoGTPases with many different cellular effectors. Myelination is an ideal place for RhoGTPases regulation, as it is the result of fine orchestration of many stimuli from at least two cell types. Recent work has revealed that RhoGTPases are required for Schwann cells to sort, ensheath, and myelinate axons. Here, we will review these recent advances showing the critical roles for RhoGTPases in various aspects of Schwann development and myelination, including the recent discovery of their involvement in Charcot-Marie-Tooth disease. Comparison with potential roles of RhoGTPases in central nervous system myelination will be drawn.
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Affiliation(s)
- M Laura Feltri
- DIBIT, San Raffaele Scientific Institute, Milano, Italy.
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20
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Krause S, Stendel C, Senderek J, Relvas JB, Suter U. Small Rho GTPases are key regulators of peripheral nerve biology in health and disease. J Peripher Nerv Syst 2009; 13:188-99. [PMID: 18844785 DOI: 10.1111/j.1529-8027.2008.00177.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A thorough knowledge of the cellular and molecular basis of the structure and function of peripheral nerves is of paramount importance not only for a better understanding of the fascinating biology of the peripheral nervous system but also for providing critical insights into the various diseases affecting peripheral nerves as the firm foundation of potential treatments. Genetic approaches in model organisms, in combination with research on hereditary forms of neuropathies, have contributed significantly to our progress in this field. In this review, we will focus on recent advances using these synergistic approaches that led to the identification of small Rho GTPases and their regulators as crucial functional players in proper development and function of myelinated peripheral nerves, with a particular emphasis on the cell biology of Schwann cells in health and disease.
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Affiliation(s)
- Sven Krause
- Institute of Cell Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
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21
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Abstract
The Rho GTPase family of signaling proteins controls a wide range of highly dynamic cellular processes. Activation of Rho GTPases can be investigated and quantified in cell extracts using so-called pull-down assays. Proteins that bind specifically to the activated form of the Rho GTPase are used to capture it onto a bead support. Western blotting of the captured samples with specific antibodies then allows for quantification of the level of Rho GTPase activation in the sample. This unit describes the techniques for preparing the reagents required for assays of RhoA, Rac, and Cdc42 and gives practical tips for the successful application of the assay in a range of situations.
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Affiliation(s)
- Stéphanie Pellegrin
- Mammalian Cell Biology Laboratory, Department of Biochemistry, School of Medical Sciences, University of Bristol, United Kingdom
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22
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Jung CG, Kim HJ, Miron VE, Cook S, Kennedy TE, Foster CA, Antel JP, Soliven B. Functional consequences of S1P receptor modulation in rat oligodendroglial lineage cells. Glia 2007; 55:1656-67. [PMID: 17876806 DOI: 10.1002/glia.20576] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Fingolimod (FTY720) and its phosphorylated form FTY720P are modulators of sphingosine-1-phosphate (S1P) receptors, which are G-protein coupled receptors linked to cell migration and vascular maturation. The efficacy of FTY720 in autoimmune diseases such as multiple sclerosis and its animal models has been attributed to its inhibition of lymphocyte trafficking to target organs. In this study, we examined the role of S1P receptors in cultured rat oligodendrocytes (OLGs) and OLG progenitor cells (OPCs) using the active phosphorylated form of FTY720. We found that (1) FTY720P improves the survival of neonatal rat OLGs during serum withdrawal, which is associated with the phosphorylation of extracellular signal regulated kinases (ERK1/2) and Akt; (2) FTY720P regulates OPC differentiation into OLGs in a concentration-dependent manner; and (3) S1P receptors are differentially modulated by platelet-derived growth factor (PDGF) resulting in downregulation of S1P5 and upregulation of S1P1 in OPCs. In addition, siRNA studies revealed that S1P1 participates in PDGF-induced OPC mitogenesis. We conclude that S1P1 and S1P5 serve different functions during oligodendroglial development, and possibly during remyelination.
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Affiliation(s)
- C G Jung
- Department of Neurology, University of Chicago, Chicago, Illinois 60637, USA
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23
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Endogenous RGS proteins attenuate Galpha(i)-mediated lysophosphatidic acid signaling pathways in ovarian cancer cells. Cell Signal 2007; 20:381-9. [PMID: 18083345 DOI: 10.1016/j.cellsig.2007.10.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 10/30/2007] [Indexed: 01/06/2023]
Abstract
Lysophosphatidic acid is a bioactive phospholipid that is produced by and stimulates ovarian cancer cells, promoting proliferation, migration, invasion, and survival. Effects of LPA are mediated by cell surface G-protein coupled receptors (GPCRs) that activate multiple heterotrimeric G-proteins. G-proteins are deactivated by Regulator of G-protein Signaling (RGS) proteins. This led us to hypothesize that RGS proteins may regulate G-protein signaling pathways initiated by LPA in ovarian cancer cells. To determine the effect of endogenous RGS proteins on LPA signaling in ovarian cancer cells, we compared LPA activity in SKOV-3 ovarian cancer cells expressing G(i) subunit constructs that are either insensitive to RGS protein regulation (RGSi) or their RGS wild-type (RGSwt) counterparts. Both forms of the G-protein contained a point mutation rendering them insensitive to inhibition with pertussis toxin, and cells were treated with pertussis toxin prior to experiments to eliminate endogenous G(i/o) signaling. The potency and efficacy of LPA-mediated inhibition of forskolin-stimulated adenylyl cyclase activity was enhanced in cells expressing RGSi G(i) proteins as compared to RGSwt G(i). We further showed that LPA signaling that is subject to RGS regulation terminates much faster than signaling thru RGS insensitive G-proteins. Finally, LPA-stimulated SKOV-3 cell migration, as measured in a wound-induced migration assay, was enhanced in cells expressing Galpha(i2) RGSi as compared to cells expressing Galpha(i2) RGSwt, suggesting that endogenous RGS proteins in ovarian cancer cells normally attenuate this LPA effect. These data establish RGS proteins as novel regulators of LPA signaling in ovarian cancer cells.
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Mullershausen F, Craveiro LM, Shin Y, Cortes-Cros M, Bassilana F, Osinde M, Wishart WL, Guerini D, Thallmair M, Schwab ME, Sivasankaran R, Seuwen K, Dev KK. Phosphorylated FTY720 promotes astrocyte migration through sphingosine-1-phosphate receptors. J Neurochem 2007; 102:1151-61. [PMID: 17488279 DOI: 10.1111/j.1471-4159.2007.04629.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Sphingosine-1-phosphate (S1P) receptors are widely expressed in the central nervous system where they are thought to regulate glia cell function. The phosphorylated version of fingolimod/FTY720 (FTY720P) is active on a broad spectrum of S1P receptors and the parent compound is currently in phase III clinical trials for the treatment of multiple sclerosis. Here, we aimed to identify which cell type(s) and S1P receptor(s) of the central nervous system are targeted by FTY720P. Using calcium imaging in mixed cultures from embryonic rat cortex we show that astrocytes are the major cell type responsive to FTY720P in this assay. In enriched astrocyte cultures, we detect expression of S1P1 and S1P3 receptors and demonstrate that FTY720P activates Gi protein-mediated signaling cascades. We also show that FTY720P as well as the S1P1-selective agonist SEW2871 stimulate astrocyte migration. The data indicate that FTY720P exerts its effects on astrocytes predominantly via the activation of S1P1 receptors, whereas S1P signals through both S1P1 and S1P3 receptors. We suggest that this distinct pharmacological profile of FTY720P, compared with S1P, could play a role in the therapeutic effects of FTY720 in multiple sclerosis.
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Affiliation(s)
- Florian Mullershausen
- Department of G Protein-Coupled Receptors, Novartis Institutes for BioMedical Research, Novartis Pharma, Basel, Switzerland
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25
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Mullershausen F, Craveiro LM, Shin Y, Cortes-Cros M, Bassilana F, Osinde M, Wishart WL, Guerini D, Thallmair M, Schwab ME, Sivasankaran R, Seuwen K, Dev KK. Phosphorylated FTY720 promotes astrocyte migration through sphingosine-1-phosphate receptors. J Neurochem 2007. [DOI: 10.1111/j.1471-4159.2007.4629.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Nebesio TD, Ming W, Chen S, Clegg T, Yuan J, Yang Y, Estwick SA, Li Y, Li X, Hingtgen CM, Yang FC. Neurofibromin-deficient Schwann cells have increased lysophosphatidic acid dependent survival and migration-implications for increased neurofibroma formation during pregnancy. Glia 2007; 55:527-36. [PMID: 17236191 DOI: 10.1002/glia.20482] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Neurofibromas are the clinical hallmark of neurofibromatosis Type 1 (NF1), a genetic disorder caused by mutations of the NF1 tumor suppressor gene, which encodes neurofibromin that functions as a GTPase activating protein (GAP) for Ras. During pregnancy, up to 50% of existing neurofibromas enlarge and as many as 60% of new neurofibromas appear for the first time. Lysophosphatidic acid (LPA) is a prototypic lysophospholipid that modulates cell migration and survival of Schwann cells (SCs) and is made in increasing concentrations throughout pregnancy. We addressed the influence of LPA on the biochemical and cellular functions of SCs with a homozygous mutation of the murine homologue of the NF1 gene (Nf1-/-). LPA promoted F-actin polymerization and increased migration and survival of Nf1-/- SCs as compared to wild type (WT) SCs. Furthermore, LPA induced a higher level of Ras-GTP and Akt phosphorylation in Nf1-/- SCs as compared to WT cells. Pharmacologic inhibition or siRNA for the p85beta regulatory subunit of Class I A PI3-K significantly reduced LPA-induced Schwann cell survival and migration. Introduction of NF1-GRD reconstitution was sufficient to normalize the LPA-mediated motility of Nf1-/- SCs. As LPA modulates excessive cell survival and motility of Nf1-/- SCs, which are the tumorigenic cells in NF1, targeting PI3-K may be a potential therapeutic approach in diminishing the development and progression of neurofibromas in pregnant women with NF1.
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Affiliation(s)
- Todd D Nebesio
- Department of Pediatrics, Herman B. Wells Center for Pediatric Cancer Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
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27
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Malek AM, Xu C, Kim ES, Alper SL. Hypertonicity triggers RhoA-dependent assembly of myosin-containing striated polygonal actin networks in endothelial cells. Am J Physiol Cell Physiol 2006; 292:C1645-59. [PMID: 17192281 DOI: 10.1152/ajpcell.00533.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Endothelial cells respond to mechanical stresses of the circulation with cytoskeletal rearrangements such as F-actin stress fiber alignment along the axis of fluid flow. Endothelial cells are exposed to hypertonic stress in the renal medulla or during mannitol treatment of cerebral edema. We report here that arterial endothelial cells exposed to hypertonic stress rearranged F-actin into novel actin-myosin II fibers with regular 0.5-microm striations, in which alpha-actinin colocalizes with actin. These striated fibers assembled over hours into three-dimensional, irregular, polygonal actin networks most prominent at the cell base, and occasionally surrounding the nucleus in a geodesic-like structure. Hypertonicity-induced assembly of striated polygonal actin networks was inhibited by cytochalasin D, blebbistatin, cell ATP depletion, and intracellular Ca(2+) chelation but did not require intact microtubules, regulatory volume increase, or de novo RNA or protein synthesis. Striated polygonal actin network assembly was insensitive to inhibitors of MAP kinases, tyrosine kinases, or phosphatidylinositol 3-kinase, but was prevented by C3 exotoxin, by the RhoA kinase inhibitor Y-27632, and by overexpressed dominant-negative RhoA. In contrast, overexpression of dominant-negative Rac or of dominant-negative cdc42 cDNAs did not prevent striated polygonal actin network assembly. The actin networks described here are novel in structure, as striated actin-myosin structures in nonmuscle cells, as a cellular response to hypertonicity, and as a cytoskeletal regulatory function of RhoA. Endothelial cells may use RhoA-dependent striated polygonal actin networks, possibly in concert with cytoskeletal load-bearing elements, as a contractile, tension-generating component of their defense against isotropic compressive forces.
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Affiliation(s)
- Adel M Malek
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA.
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28
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Giussani P, Ferraretto A, Gravaghi C, Bassi R, Tettamanti G, Riboni L, Viani P. Sphingosine-1-phosphate and calcium signaling in cerebellar astrocytes and differentiated granule cells. Neurochem Res 2006; 32:27-37. [PMID: 17151916 DOI: 10.1007/s11064-006-9219-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 11/03/2006] [Indexed: 02/01/2023]
Abstract
S1P is involved in the regulation of multiple biological processes (cell survival, growth, migration and differentiation) both in neurons and glial cells. The study was aimed at investigating the possible effects of S1P on calcium signaling in cerebellar astrocytes and differentiated granule cells. In cerebellar astrocytes S1P is able to mediate calcium signaling mainly through Gi protein coupled receptors, whereas in differentiated neurons it failed to evoke any calcium signaling, despite acting both extracellularly and intracellularly. The data indicate strict cell specificity in S1P-evoked calcium response, which could be relevant to communication between neurons and glial cells in the cerebellum.
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Affiliation(s)
- Paola Giussani
- Department of Medical Chemistry, Biochemistry and Biotechnology, L.I.T.A. via F. Cervi 93, 20090 Segrate (Milan), Italy
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29
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Ipatova OM, Torkhovskaya TI, Zakharova TS, Khalilov EM. Sphingolipids and cell signaling: involvement in apoptosis and atherogenesis. BIOCHEMISTRY (MOSCOW) 2006; 71:713-22. [PMID: 16903825 DOI: 10.1134/s0006297906070030] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This review considers various functional aspects of cell sphingolipids (sphingomyelin, ceramides) and lysosphingolipids (sphingosine-1-phosphate (S1P) and sphingosine phosphorylcholine). Good evidence now exists that they are actively involved in numerous cell-signaling processes. The enzymes responsible for formation and interconversion of cell sphingolipids (sphingomyelinases, ceramidase, sphingosine kinase, S1P-lyase) exhibit high sensitivity to various stimulating factors. This determines the content of individual cell sphingolipids and therefore the mode of cell response. Special attention is paid to preferential localization of sphingolipids in the rigid plasma membrane domains (rafts) coupled to many signal proteins. The suggestion is discussed that ceramide signaling may be based on the modification of fine molecular interactions in lipid rafts, resulting in its clusterization inducing the signal transduction. The review also highlights involvement of sphingolipids in cell proliferation, apoptosis, and in processes implicated to atherosclerosis.
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Affiliation(s)
- O M Ipatova
- Institute of Biomedical Chemistry, Moscow, 119121, Russia
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30
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Bassi R, Anelli V, Giussani P, Tettamanti G, Viani P, Riboni L. Sphingosine-1-phosphate is released by cerebellar astrocytes in response to bFGF and induces astrocyte proliferation through Gi-protein-coupled receptors. Glia 2006; 53:621-30. [PMID: 16470810 DOI: 10.1002/glia.20324] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The mitogenic role of sphingosine-1-phosphate (S1P) and its involvement in basic fibroblast growth factor (bFGF)-induced proliferation were examined in primary cultures of cerebellar astrocytes. Exposure to bFGF resulted in a rapid increase of extracellular S1P formation, bFGF inducing astrocytes to release S1P, but not sphingosine kinase, in the extracellular milieu. The SK inhibitor N,N-dimethylsphingosine inhibited S1P release as well as bFGF-induced growth stimulation. S1P application in quiescent astrocytes caused a dose-dependent increase in DNA synthesis. This gliotrophic effect was induced by a brief exposure to low nanomolar S1P, mimicked by the S1P receptor agonist dihydro-S1P, and inhibited by pertussis toxin (PTX), an inactivator of G(i)/G(o)-proteins. S1P also induced activation of extracellular signal-regulated kinase that was inhibited again by PTX. Moreover, the S1P lyase inhibitor 4-deoxypyridoxine induced the cellular accumulation of S1P but did not affect DNA synthesis. These results support the view that S1P exerted a mitogenic effect on cerebellar astrocytes extracellularly, most likely through cell surface S1P receptors. In agreement, mRNAs for S1P1, S1P2, and S1P3 receptors are expressed in cerebellar astrocytes (Anelli et al., 2005. J Neurochem 92:1204-1215). Ceramide, a negative regulator of astrocyte proliferation and down-regulated by bFGF (Riboni et al., 2002. Cerebellum 1:129-135), efficiently inhibited S1P-induced proliferation. The S1P action appears to be part of an autocrine/paracrine cascade stimulated by bFGF and, together with ceramide down-regulation, essential for astrocytes to respond to bFGF. The results suggest that S1P and bFGF/S1P may play an important role in physiopathological glial proliferation, such as brain development, reactive gliosis and brain tumor formation.
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Affiliation(s)
- Rosaria Bassi
- Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, LITA-Segrate, Milan, Italy
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31
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Rouach N, Pébay A, Même W, Cordier J, Ezan P, Etienne E, Giaume C, Tencé M. S1P inhibits gap junctions in astrocytes: involvement of Giand Rho GTPase/ROCK. Eur J Neurosci 2006; 23:1453-64. [PMID: 16553609 DOI: 10.1111/j.1460-9568.2006.04671.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sphingosine-1-phosphate (S1P) is a potent and pleiotropic bioactive lysophospholipid mostly released by activated platelets that acts on its target cells through its own G protein-coupled receptors. We have previously reported that mouse striatal astrocytes expressed mRNAs for S1P1 and S1P3 receptors and proliferate in response to S1P. Here, we investigated the effect of S1P on gap junctions. We show that a short-term exposure of astrocytes to S1P causes a robust inhibition of gap junctional communication, as demonstrated by dye coupling experiments and double voltage-clamp recordings of junctional currents. The inhibitory effect of S1P on dye coupling involves the activation of both Gi and Rho GTPases. Rho-associated kinase (ROCK) also plays a critical role. The capacity of S1P to activate a Rho/ROCK axis in astrocytes is demonstrated by the typical remodeling of actin cytoskeleton. Connexin43, the protein forming gap junction channels, is a target of the Gi- and Rho/ROCK-mediated signaling cascades. Indeed, as shown by Western blots and confocal immunofluorescence, its nonphosphorylated form increases following S1P treatment and this change does not occur when both cascades are disrupted. This novel effect of S1P may have an important physiopathological significance when considering the proposed roles for astrocyte gap junctions on neuronal survival.
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Affiliation(s)
- Nathalie Rouach
- INSERM U587, Collège de France, 11, Place Marcelin Berthelot, 75005 Paris, France
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Budnik LT, Brunswig-Spickenheier B. Differential effects of lysolipids on steroid synthesis in cells expressing endogenous LPA2 receptor. J Lipid Res 2005; 46:930-41. [PMID: 15716590 DOI: 10.1194/jlr.m400423-jlr200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Incubation of ovarian luteal cells with the bioactive lipid mediator lysophosphatidic acid (LPA) for 180 min abolishes gonadotropin-induced steroid production with no attenuation of the cyclic AMP accumulation. Treatment with the lysolipid also diminishes [14C]steroid production in cells preloaded with either [14C]cholesterol or [14C]acetate. Neither the expression of steroidogenic acute regulatory (StAR) protein nor in vitro steroid synthesis is affected in isolated mitochondrial fractions. The LPA-induced attenuation of steroid production occurs only in the mid-cycle corpus luteum and is associated with a transient endogenous expression of mRNA for the lysophosphatidic acid A2 (LPA2) receptor (with no concomitant changes in the expression of LPA1 receptor). Expression of LPA2 is accompanied by LPA-induced sphingosine-1-phosphate (S1P) production. Because luteal cells, in the presence of the sphingosine kinase inhibitor dihydrosphingosine, can overcome the inhibitory effects of LPA on steroid synthesis, we suggest the possible requirement of intracellular S1P production. Interestingly, no LPA-induced inhibition of 8Br-cAMP-stimulated progesterone synthesis can be detected in Leydig tumor cell line MA10 cells expressing only LPA2 receptor. Surprisingly, however, exogenous S1P inhibits agonist-stimulated progesterone in both cell types by inhibiting cyclic AMP accumulation, suggesting different mechanisms of action.
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Affiliation(s)
- Lygia T Budnik
- Institute for Hormone and Fertility Research, Anatomy I, University Hospital Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany.
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