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The unfolded protein response is a major mechanism by which LRP1 regulates Schwann cell survival after injury. J Neurosci 2011; 31:13376-85. [PMID: 21940431 DOI: 10.1523/jneurosci.2850-11.2011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In peripheral nerve injury, Schwann cells (SCs) must survive to exert a continuing and essential role in successful nerve regeneration. Herein, we show that peripheral nerve injury is associated with activation of endoplasmic reticulum (ER) stress and the adaptive unfolded protein response (UPR). The UPR culminates in expression of C/EBP homology protein (CHOP), a proapoptotic transcription factor in SCs, unless counteracted by LDL receptor-related protein-1 (LRP1), which serves as a major activator of phosphatidylinositol 3-kinase (PI3K). Sciatic nerve crush injury in rats induced expression of the ER chaperone GRP78/BIP, reflecting an early, corrective phase of the UPR. However, when LRP1 signaling was inhibited with receptor-associated protein, PI3K activity was decreased and CHOP protein expression increased, particularly in myelinating SCs. In cultured SCs, the PKR-like ER kinase target eIF2α was phosphorylated and CHOP was induced by (1) inhibiting PI3K, (2) treating the cells with tumor necrosis factor-α (TNF-α), or (3) genetic silencing of LRP1. CHOP gene deletion in SCs decreased cell death in response to TNF-α. Furthermore, the effects of TNF-α on phosphorylated eIF2α, CHOP, and SC death were blocked by adding LRP1 ligands that augment LRP1-dependent cell signaling to PI3K. Collectively, our results support a model in which UPR-activated signaling pathways represent a major challenge to SC survival in nerve injury. LRP1 functions as a potent activator of PI3K in SCs and, by this mechanism, limits SC apoptosis resulting from increased CHOP expression in nerve injury.
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52
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Jia W, Eneh JO, Ratnaparkhe S, Altman MK, Murph MM. MicroRNA-30c-2* expressed in ovarian cancer cells suppresses growth factor-induced cellular proliferation and downregulates the oncogene BCL9. Mol Cancer Res 2011; 9:1732-45. [PMID: 22024689 DOI: 10.1158/1541-7786.mcr-11-0245] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
MicroRNAs (miRNAs) are small noncoding RNAs that function as master regulators of posttranscriptional gene expression with each miRNA negatively regulating hundreds of genes. Lysophosphatidic acid (LPA) is a mitogenic lipid present within the ovarian tumor microenvironment and induces LPA receptor activation and intracellular signaling cascades like ERK/MAPK, leading to enhanced cellular proliferation. Here, we show that in SKOV-3 and OVCAR-3 cells, LPA stimulation at concentrations ranging from 1 nmol/L to 20 μmol/L for 30 to 60 minutes increases miR-30c-2*, and this effect is mediated through a combination of receptors because knock down of multiple LPA receptors is required for inhibition. The epidermal growth factor and platelet-derived growth factor also increase miR-30c-2* transcript expression, suggesting a broader responsive role for miR-30c-2*. Thus, we investigated the functional role of miR-30c-2* through ectopic expression of synthetic miRNA precursors of mature miRNA or antagomir transfection and observed that microRNA-30c-2* reduces, and the antagomir enhances, cell proliferation and viability in OVCAR-3, cisplatin-insensitive SKOV-3 and chemoresistant HeyA8-MDR cells. Ectopic expression of miR-30c-2* reduces BCL9 mRNA transcript abundance and BCL9 protein. Consistent with this observation, miR-30c-2* ectopic expression also reduced BCL9 luciferase reporter gene expression. In comparison with IOSE cells, all cancer cells examined showed increased BCL9 expression, which is consistent with its role in tumor progression. Taken together, this suggest that growth factor induced proliferation mediates a neutralizing response by significantly increasing miR-30c-2* which reduces BCL9 expression and cell proliferation in SKOV-3 and OVCAR-3 cells, likely as a mechanism to regulate signal transduction downstream.
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Affiliation(s)
- Wei Jia
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, GA 30602, USA
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53
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Funke M, Zhao Z, Xu Y, Chun J, Tager AM. The lysophosphatidic acid receptor LPA1 promotes epithelial cell apoptosis after lung injury. Am J Respir Cell Mol Biol 2011; 46:355-64. [PMID: 22021336 DOI: 10.1165/rcmb.2010-0155oc] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Increased epithelial cell apoptosis in response to lung injury has been implicated in the development of idiopathic pulmonary fibrosis (IPF), but the molecular pathways promoting epithelial cell apoptosis in this disease have yet to be fully identified. Lysophosphatidic acid (LPA), which we have previously demonstrated to mediate bleomycin lung injury-induced fibroblast recruitment and vascular leak in mice and fibroblast recruitment in patients with IPF, is an important regulator of survival and apoptosis in many cell types. We now show that LPA signaling through its receptor LPA(1) promotes epithelial cell apoptosis induced by bleomycin injury. The number of apoptotic cells present in the alveolar and bronchial epithelia of LPA(1)-deficient mice was significantly reduced compared with wild-type mice at Day 3 after bleomycin challenge, as was lung caspase-3 activity. Consistent with these in vivo results, we found that LPA signaling through LPA(1) induced apoptosis in normal human bronchial epithelial cells in culture. LPA-LPA(1) signaling appeared to specifically mediate anoikis, the apoptosis of anchorage-dependent cells induced by their detachment. Similarly, LPA negatively regulated attachment of R3/1 rat alveolar epithelial cell line cells. In contrast, LPA signaling through LPA(1) promoted the resistance of lung fibroblasts to apoptosis, which has also been implicated in IPF. The ability of LPA-LPA(1) signaling to promote epithelial cell apoptosis and fibroblast resistance to apoptosis may therefore contribute to the capacity of this signaling pathway to regulate the development of pulmonary fibrosis after lung injury.
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Affiliation(s)
- Manuela Funke
- Pulmonary and Critical Care Unit, Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, 149 13th Street, Room 8301, Charlestown, MA 02129, USA.
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54
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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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55
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Castilla-Ortega E, Hoyo-Becerra C, Pedraza C, Chun J, Rodríguez De Fonseca F, Estivill-Torrús G, Santín LJ. Aggravation of chronic stress effects on hippocampal neurogenesis and spatial memory in LPA₁ receptor knockout mice. PLoS One 2011; 6:e25522. [PMID: 21980482 PMCID: PMC3183048 DOI: 10.1371/journal.pone.0025522] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 09/07/2011] [Indexed: 11/19/2022] Open
Abstract
Background The lysophosphatidic acid LPA1 receptor regulates plasticity and neurogenesis in the adult hippocampus. Here, we studied whether absence of the LPA1 receptor modulated the detrimental effects of chronic stress on hippocampal neurogenesis and spatial memory. Methodology/Principal Findings Male LPA1-null (NULL) and wild-type (WT) mice were assigned to control or chronic stress conditions (21 days of restraint, 3 h/day). Immunohistochemistry for bromodeoxyuridine and endogenous markers was performed to examine hippocampal cell proliferation, survival, number and maturation of young neurons, hippocampal structure and apoptosis in the hippocampus. Corticosterone levels were measured in another a separate cohort of mice. Finally, the hole-board test assessed spatial reference and working memory. Under control conditions, NULL mice showed reduced cell proliferation, a defective population of young neurons, reduced hippocampal volume and moderate spatial memory deficits. However, the primary result is that chronic stress impaired hippocampal neurogenesis in NULLs more severely than in WT mice in terms of cell proliferation; apoptosis; the number and maturation of young neurons; and both the volume and neuronal density in the granular zone. Only stressed NULLs presented hypocortisolemia. Moreover, a dramatic deficit in spatial reference memory consolidation was observed in chronically stressed NULL mice, which was in contrast to the minor effect observed in stressed WT mice. Conclusions/Significance These results reveal that the absence of the LPA1 receptor aggravates the chronic stress-induced impairment to hippocampal neurogenesis and its dependent functions. Thus, modulation of the LPA1 receptor pathway may be of interest with respect to the treatment of stress-induced hippocampal pathology.
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Affiliation(s)
- Estela Castilla-Ortega
- Departamento de Psicobiología y Metodología de las CC, Universidad de Málaga, Campus de Teatinos, Málaga, Spain
| | - Carolina Hoyo-Becerra
- Unidad de Investigación, Fundación IMABIS, Hospital Regional Universitario Carlos Haya, Málaga, Spain
| | - Carmen Pedraza
- Departamento de Psicobiología y Metodología de las CC, Universidad de Málaga, Campus de Teatinos, Málaga, Spain
| | - Jerold Chun
- Department of Molecular Biology, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, United States of America
| | | | - Guillermo Estivill-Torrús
- Unidad de Investigación, Fundación IMABIS, Hospital Regional Universitario Carlos Haya, Málaga, Spain
| | - Luis J. Santín
- Departamento de Psicobiología y Metodología de las CC, Universidad de Málaga, Campus de Teatinos, Málaga, Spain
- * E-mail:
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56
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Chun J, Brinkmann V. A mechanistically novel, first oral therapy for multiple sclerosis: the development of fingolimod (FTY720, Gilenya). DISCOVERY MEDICINE 2011; 12:213-28. [PMID: 21955849 PMCID: PMC3694567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Multiple sclerosis (MS) is a chronic autoimmune disorder affecting the central nervous system (CNS) through demyelination and neurodegeneration. Until recently, major therapeutic treatments have relied on agents requiring injection delivery. In September 2010, fingolimod/FTY720 (Gilenya, Novartis) was approved by the FDA as the first oral treatment for relapsing forms of MS. Fingolimod is a novel compound produced by chemical modification of a fungal precursor. Its active metabolite, formed by in vivo phosphorylation, modulates sphingosine 1-phosphate (S1P) receptors that are a subset of a larger family of cell-surface, G protein-coupled receptors (GPCRs) mediating the effects of bioactive lipids known as lysophospholipids. Fingolimod's mechanism of action in MS is not completely understood; however, its relevant biology indicates a fundamentally different mechanism compared to all previously approved MS therapies, with evolving research supporting both immunological and nervous system activities. This duality may herald a paradigm shift in the treatment of MS and other neurological disorders.
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Affiliation(s)
- Jerold Chun
- Department of Molecular Biology and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California 92037, USA
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57
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Nozaki E, Gotoh M, Hotta H, Hanazawa S, Kobayashi S, Murakami-Murofushi K. Synthesis of enantiopure 2-carba-cyclic phosphatidic acid and effects of its chirality on biological functions. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:271-7. [PMID: 21277386 DOI: 10.1016/j.bbalip.2011.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Revised: 12/29/2010] [Accepted: 01/13/2011] [Indexed: 01/20/2023]
Abstract
Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator, which has a quite unique cyclic phosphate ring at sn-2 and sn-3 positions of the glycerol backbone. We have designed and chemically synthesized several metabolically stabilized derivatives of cPA. 2-Carba-cPA (2ccPA) is one of the synthesized compounds in which the phosphate oxygen was replaced with a methylene group at the sn-2 position, and it showed much more potent biological activities than natural cPA. Here, we developed a new method of 2ccPA enantiomeric synthesis. And we examined the effects of 2ccPA enantiomers on autotaxin (ATX) activity, cancer cell invasion and nociceptive reflex. As well as racemic-2ccPA, both enantiomers showed inhibitory effects on ATX activity, cancer cell invasion and nociceptive reflex. As their effects were not significantly different from each other, the chirality of 2ccPA may not be critical for these biological functions of 2ccPA.
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Affiliation(s)
- Emi Nozaki
- Graduate School of Humanities and Sciences, Department of Life Science, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112-8610, Japan
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58
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Frugier T, Crombie D, Conquest A, Tjhong F, Taylor C, Kulkarni T, McLean C, Pébay A. Modulation of LPA Receptor Expression in the Human Brain Following Neurotrauma. Cell Mol Neurobiol 2011; 31:569-77. [DOI: 10.1007/s10571-011-9650-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 01/05/2011] [Indexed: 01/07/2023]
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59
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Goldshmit Y, Munro K, Leong SY, Pébay A, Turnley AM. LPA receptor expression in the central nervous system in health and following injury. Cell Tissue Res 2010; 341:23-32. [PMID: 20495828 DOI: 10.1007/s00441-010-0977-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 04/06/2010] [Indexed: 11/30/2022]
Abstract
Lysophosphatidic acid (LPA) is released from platelets following injury and also plays a role in neural development but little is known about its effects in the adult central nervous system (CNS). We have examined the expression of LPA receptors 1-3 (LPA(1-3)) in intact mouse spinal cord and cortical tissues and following injury. In intact and injured tissues, LPA(1) was expressed by ependymal cells in the central canal of the spinal cord and was upregulated in reactive astrocytes following spinal cord injury. LPA(2) showed low expression in intact CNS tissue, on grey matter astrocytes in spinal cord and in ependymal cells lining the lateral ventricle. Following injury, its expression was upregulated on astrocytes in both cortex and spinal cord. LPA(3) showed low expression in intact CNS tissue, viz. on cortical neurons and motor neurons in the spinal cord, and was upregulated on neurons in both regions after injury. Therefore, LPA(1-3) are differentially expressed in the CNS and their expression is upregulated in response to injury. LPA release following CNS injury may have different consequences for each cell type because of this differential expression in the adult nervous system.
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Affiliation(s)
- Yona Goldshmit
- Centre for Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
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60
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Kumar SA, Hu X, Brown M, Kuschak B, Hernandez TA, Johnston JB, Gibson SB. Lysophosphatidic acid receptor expression in chronic lymphocytic leukemia leads to cell survival mediated though vascular endothelial growth factor expression. Leuk Lymphoma 2010; 50:2038-48. [PMID: 19860625 DOI: 10.3109/10428190903275586] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Lysophosphatidic acid (LPA) protects chronic lymphocytic leukemia (CLL) cells from apoptosis. Vascular endothelial growth factor (VEGF) also protects CLL cells against apoptosis. The mechanism for LPA protection against apoptosis in CLL cells is unknown. Herein, we show CLL cells express LPA receptors LPA(1-5) but in normal B cells, LPA(1) was rarely expressed and LPA(3,) LPA(4,) and LPA(6) were undetectable whereas the other LPA receptors were expressed. LPA plasma levels are similar in patients with CLL compared to healthy controls. In contrast, plasma levels of VEGF are elevated in patients with CLL compared to healthy controls and LPA treatment induced VEGF secretion in CLL cells. CLL cells also express VEGF receptors and LPA protection against Flu induced apoptosis is blocked by inhibition of VEGF receptor activation. These results indicate that LPA protects CLL cells from apoptosis through higher expression of LPA receptors and autocrine production of VEGF.
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61
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Choi JW, Herr DR, Noguchi K, Yung YC, Lee CW, Mutoh T, Lin ME, Teo ST, Park KE, Mosley AN, Chun J. LPA receptors: subtypes and biological actions. Annu Rev Pharmacol Toxicol 2010; 50:157-86. [PMID: 20055701 DOI: 10.1146/annurev.pharmtox.010909.105753] [Citation(s) in RCA: 648] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Lysophosphatidic acid (LPA) is a small, ubiquitous phospholipid that acts as an extracellular signaling molecule by binding to and activating at least five known G protein-coupled receptors (GPCRs): LPA(1)-LPA(5). They are encoded by distinct genes named LPAR1-LPAR5 in humans and Lpar1-Lpar5 in mice. The biological roles of LPA are diverse and include developmental, physiological, and pathophysiological effects. This diversity is mediated by broad and overlapping expression patterns and multiple downstream signaling pathways activated by cognate LPA receptors. Studies using cloned receptors and genetic knockout mice have been instrumental in uncovering the significance of this signaling system, notably involving basic cellular processes as well as multiple organ systems such as the nervous system. This has further provided valuable proof-of-concept data to support LPA receptors and LPA metabolic enzymes as targets for the treatment of medically important diseases that include neuropsychiatric disorders, neuropathic pain, infertility, cardiovascular disease, inflammation, fibrosis, and cancer.
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Affiliation(s)
- Ji Woong Choi
- Department of Molecular Biology, Helen L. Dorris Institute for Neurological and Psychiatric Disorders, The Scripps Research Institute, La Jolla, California 92037, USA
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62
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Giunta S, Castorina A, Adorno A, Mazzone V, Carnazza ML, D'Agata V. PACAP and VIP affect NF1 expression in rat malignant peripheral nerve sheath tumor (MPNST) cells. Neuropeptides 2010; 44:45-51. [PMID: 19919880 DOI: 10.1016/j.npep.2009.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 09/14/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
In our previous study we have identified PACAP, VIP and their receptors in rat malignant peripheral nerve sheath tumor (MPNST) cells, thus showing anti-apoptotic roles. Recently it has been shown that the tumor suppressor neurofibromin, encoded by the Neurofibromatosis type I (NF1) gene, promotes MPNST cells sensitivity to apoptosis after serum withdrawal. In the present study we investigated whether PACAP or VIP negatively regulate NF1 expression under normal or serum-dependent pro-apoptotic culture conditions. Results indicated that serum itself significantly influenced gene and protein levels. In fact, the low NF1 levels of cells cultured in normal serum-containing medium were remarkably increased in cells switched to low- or no-serum after 24h and 48 h. Treatment with 100 nM PACAP or VIP did not affect NF1 expression when using normal amounts of serum, whereas it significantly inhibited transcript and protein levels both in low- or no-serum cultured cells. In particular, PACAP reduced NF1 levels already after 24h in low-serum cultured cells, while VIP showed a similar effect only after serum deprivation. However, both PACAP and VIP downregulated gene and protein levels within 48 h either in low-dose and serum-starved cells. Results were confirmed by fluorescence microscopy, showing that 100 nM PACAP or VIP attenuated neurofibromin cytoplasmic localization only in low- or no-serum cultured cells. The present study provides a comprehensive analysis of both neuropeptides effect on NF1 expression in normal, low- or serum-starved MPNST cells, ameliorating the hypothesis that resistance to apoptosis in serum-deprived cells might be correlated to PACAP-/VIP-induced NF1 inhibition.
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Affiliation(s)
- Salvatore Giunta
- Department of Anatomy, Diagnostic Pathology, Legal Medicine, Hygiene and Public Health, University of Catania, Catania, Italy
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63
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Yung YC, Kennedy G, Chun J. Identification of neural programmed cell death through the detection of DNA fragmentation in situ and by PCR. ACTA ACUST UNITED AC 2009; Chapter 3:Unit 3.8. [PMID: 19575470 DOI: 10.1002/0471142301.ns0308s48] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Programmed cell death is a fundamental process for the development and somatic maintenance of organisms. This unit describes methods for visualizing both dying cells in situ and for detection of nucleosomal ladders. A description of various current detection strategies is provided, as well as support protocols for preparing positive and negative controls and for preparing genomic DNA.
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Affiliation(s)
- Yun C Yung
- Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, La Jolla, California, USA
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64
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Rodrigues LS, da Silva Maeda E, Moreira MEC, Tempone AJ, Lobato LS, Ribeiro-Resende VT, Alves L, Rossle S, Lopes UG, Pessolani MCV. Mycobacterium leprae induces insulin-like growth factor and promotes survival of Schwann cells upon serum withdrawal. Cell Microbiol 2009; 12:42-54. [PMID: 19732058 DOI: 10.1111/j.1462-5822.2009.01377.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Peripheral nerve lesions are considered the most relevant symptoms of leprosy, a chronic infectious disease caused by Mycobacterium leprae. The strategies employed by M. leprae to infect and multiply inside Schwann cells (SCs), however, remain poorly understood. In this study, it is shown that treatment of SCs with M. leprae significantly decreased cell death induced by serum deprivation. Not displayed by Mycobacterium smegmatis or Mycobacterium bovis BCG, the M. leprae survival effect was both dose dependent and specific. The conditioned medium (CM) of M. leprae-treated cultures was seen to mimic the protective effect of the bacteria, suggesting that soluble factors secreted by SCs in response to M. leprae were involved in cell survival. Indeed, by quantitative RT-PCR and dot blot/ELISA, it was demonstrated that M. leprae induced the expression and secretion of the SC survival factor insulin-like growth factor-I. Finally, the involvement of this hormone in M. leprae-induced SC survival was confirmed in experiments with neutralizing antibodies. Taken together, the results of this study delineate an important strategy for the successful colonization of M. leprae in the nerve based on the survival maintenance of the host cell through induction of IGF-I production.
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65
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Ishii S, Noguchi K, Yanagida K. Non-Edg family lysophosphatidic acid (LPA) receptors. Prostaglandins Other Lipid Mediat 2009; 89:57-65. [DOI: 10.1016/j.prostaglandins.2009.06.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Accepted: 06/03/2009] [Indexed: 12/23/2022]
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66
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Williams JR, Khandoga AL, Goyal P, Fells JI, Perygin DH, Siess W, Parrill AL, Tigyi G, Fujiwara Y. Unique ligand selectivity of the GPR92/LPA5 lysophosphatidate receptor indicates role in human platelet activation. J Biol Chem 2009; 284:17304-17319. [PMID: 19366702 PMCID: PMC2719366 DOI: 10.1074/jbc.m109.003194] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Lysophosphatidic acid (LPA) is a ligand for LPA(1-3) of the endothelial differentiation gene family G-protein-coupled receptors, and LPA(4-8) is related to the purinergic family G-protein-coupled receptor. Because the structure-activity relationship (SAR) of GPR92/LPA(5) is limited and whether LPA is its preferred endogenous ligand has been questioned in the literature, in this study we applied a combination of computational and experimental site-directed mutagenesis of LPA(5) residues predicted to interact with the headgroup of LPA. Four residues involved in ligand recognition in LPA(5) were identified as follows: R2.60N mutant abolished receptor activation, whereas H4.64E, R6.62A, and R7.32A greatly reduced receptor activation. We also investigated the SAR of LPA(5) using LPA analogs and other non-lysophospholipid ligands. SAR revealed that the rank order of agonists is alkyl glycerol phosphate > LPA > farnesyl phosphates >> N-arachidonoylglycine. These results confirm LPA(5) to be a bona fide lysophospholipid receptor. We also evaluated several compounds with previously established selectivity for the endothelial differentiation gene receptors and found several that are LPA(5) agonists. A pharmacophore model of LPA(5) binding requirements was developed for in silico screening, which identified two non-lipid LPA(5) antagonists. Because LPA(5) transcripts are abundant in human platelets, we tested its antagonists on platelet activation and found that these non-lipid LPA(5) antagonists inhibit platelet activation. The present results suggest that selective inhibition of LPA(5) may provide a basis for future anti-thrombotic therapies.
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Affiliation(s)
- Jesica R Williams
- From the Department of Chemistry and Computational Research on Materials Institute, University of Memphis, Memphis, Tennessee 38152
| | - Anna L Khandoga
- Institute for Prevention of Cardiovascular Diseases, Medical Faculty, University of Munich, 80336 Munich, Germany
| | - Pankaj Goyal
- Institute for Prevention of Cardiovascular Diseases, Medical Faculty, University of Munich, 80336 Munich, Germany
| | - James I Fells
- From the Department of Chemistry and Computational Research on Materials Institute, University of Memphis, Memphis, Tennessee 38152
| | - Donna H Perygin
- From the Department of Chemistry and Computational Research on Materials Institute, University of Memphis, Memphis, Tennessee 38152
| | - Wolfgang Siess
- Institute for Prevention of Cardiovascular Diseases, Medical Faculty, University of Munich, 80336 Munich, Germany
| | - Abby L Parrill
- From the Department of Chemistry and Computational Research on Materials Institute, University of Memphis, Memphis, Tennessee 38152
| | - Gabor Tigyi
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Yuko Fujiwara
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163.
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67
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Woodhoo A, Sommer L. Development of the Schwann cell lineage: from the neural crest to the myelinated nerve. Glia 2009; 56:1481-1490. [PMID: 18803317 DOI: 10.1002/glia.20723] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The myelinating and nonmyelinating Schwann cells in peripheral nerves are derived from the neural crest, which is a transient and multipotent embryonic structure that also generates the other main glial subtypes of the peripheral nervous system (PNS). Schwann cell development occurs through a series of transitional embryonic and postnatal phases, which are tightly regulated by a number of signals. During the early embryonic phases, neural crest cells are specified to give rise to Schwann cell precursors, which represent the first transitional stage in the Schwann cell lineage, and these then generate the immature Schwann cells. At birth, the immature Schwann cells differentiate into either the myelinating or nonmyelinating Schwann cells that populate the mature nerve trunks. In this review, we will discuss the biology of the transitional stages in embryonic and early postnatal Schwann cell development, including the phenotypic differences between them and the recently identified signaling pathways, which control their differentiation and maintenance. In addition, the role and importance of the microenvironment in which glial differentiation takes place will be discussed.
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Affiliation(s)
- Ashwin Woodhoo
- Department of Anatomy and Developmental Biology, University College London, London, United Kingdom.
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68
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Lin ME, Herr DR, Chun J. Lysophosphatidic acid (LPA) receptors: signaling properties and disease relevance. Prostaglandins Other Lipid Mediat 2009; 91:130-8. [PMID: 20331961 DOI: 10.1016/j.prostaglandins.2009.02.002] [Citation(s) in RCA: 283] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 02/13/2009] [Accepted: 02/18/2009] [Indexed: 12/20/2022]
Abstract
Lysophosphatidic acid (LPA), a water-soluble phospholipid, has gained significant attention in recent years since the discovery that it acts as a potent signaling molecule with wide-ranging effects on many different target tissues. There are currently five identified G protein-coupled receptors for LPA and more are undergoing validation. The complexity of the expression pattern and signaling properties of LPA receptors results in multiple influences on developmental, physiological, and pathological processes. This review provides a summary of LPA receptor signaling and current views on the potential involvement of this pathway in human diseases that include cardiovascular, cancer, neuropathic pain, neuropsychiatric disorders, reproductive disorders, and fibrosis. The involvement of LPA signaling in these processes implicates multiple, potential drug targets including LPA receptor subtypes and LPA metabolizing enzymes. Modulation of LPA signaling may thus provide therapeutic inroads for the treatment of human disease.
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Affiliation(s)
- Mu-En Lin
- Department of Molecular Biology, Helen L. Dorris Institute for Neurological and Psychiatric Disorders, The Scripps Research Institute, La Jolla, CA 92037, USA
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69
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The hemopexin domain of matrix metalloproteinase-9 activates cell signaling and promotes migration of schwann cells by binding to low-density lipoprotein receptor-related protein. J Neurosci 2008; 28:11571-82. [PMID: 18987193 DOI: 10.1523/jneurosci.3053-08.2008] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Low-density lipoprotein receptor-related protein (LRP-1) is an endocytic receptor for diverse proteins, including matrix metalloproteinase-9 (MMP-9), and a cell-signaling receptor. In the peripheral nervous system (PNS), LRP-1 is robustly expressed by Schwann cells only after injury. Herein, we demonstrate that MMP-9 activates extracellular-signal-regulated kinase (ERK1/2) and Akt in Schwann cells in culture. MMP-9 also promotes Schwann cell migration. These activities require LRP-1. MMP-9-induced cell signaling and migration were blocked by inhibiting MMP-9-binding to LRP-1 with receptor-associated protein (RAP) or by LRP-1 gene silencing. The effects of MMP-9 on Schwann cell migration also were inhibited by blocking the cell-signaling response. An antibody targeting the hemopexin domain of MMP-9, which mediates the interaction with LRP-1, blocked MMP-9-induced cell signaling and migration. Furthermore, a novel glutathione-S-transferase fusion protein (MMP-9-PEX), which includes only the hemopexin domain of MMP-9, replicated the activities of intact MMP-9, activating Schwann cell signaling and migration by an LRP-1-dependent pathway. Constitutively active MEK1 promoted Schwann cell migration; in these cells, MMP-9-PEX had no further effect, indicating that ERK1/2 activation is sufficient to explain the effects of MMP-9-PEX on Schwann cell migration. Injection of MMP-9-PEX into sciatic nerves, 24 h after crush injury, robustly increased phosphorylation of ERK1/2 and Akt. This response was inhibited by RAP. MMP-9-PEX failed to activate cell signaling in uninjured nerves, consistent with the observation that Schwann cells express LRP-1 at significant levels only after nerve injury. These results establish LRP-1 as a cell-signaling receptor for MMP-9, which may be significant in regulating Schwann cell migration and physiology in PNS injury.
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70
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Autotaxin protects MCF-7 breast cancer and MDA-MB-435 melanoma cells against Taxol-induced apoptosis. Oncogene 2008; 28:1028-39. [PMID: 19079345 DOI: 10.1038/onc.2008.442] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Autotaxin (ATX) promotes cancer cell survival, growth, migration, invasion and metastasis. ATX converts extracellular lysophosphatidylcholine (LPC) into lysophosphatidate (LPA). As these lipids have been reported to affect cell signaling through their own G-protein-coupled receptors, ATX could modify the balance of this signaling. Also, ATX affects cell adhesion independently of its catalytic activity. We investigated the interactions of ATX, LPC and LPA on the apoptotic effects of Taxol, which is commonly used in breast cancer treatment. LPC had no significant effect on Taxol-induced apoptosis in MCF-7 breast cancer cells, which do not secrete significant ATX. Addition of incubation medium from MDA-MB-435 melanoma cells, which secrete ATX, or recombinat ATX enabled LPC to inhibit Taxol-induced apoptosis of MCF-7 cells. Inhibiting ATX activity blocked this protection against apoptosis. We conclude that LPC has no significant effect in protecting MCF-7 cells against Taxol treatment unless it is converted to LPA by ATX. LPA strongly antagonized Taxol-induced apoptosis through stimulating phosphatidylinositol 3-kinase and inhibiting ceramide formation. LPA also partially reversed the Taxol-induced arrest in the G2/M phase of the cell cycle. Our results support the hypothesis that therapeutic inhibition of ATX activity could improve the efficacy of Taxol as a chemotherapeutic agent for cancer treatment.
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71
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Choi JW, Lee CW, Chun J. Biological roles of lysophospholipid receptors revealed by genetic null mice: an update. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1781:531-9. [PMID: 18407842 PMCID: PMC2657083 DOI: 10.1016/j.bbalip.2008.03.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Accepted: 03/12/2008] [Indexed: 12/27/2022]
Abstract
Two lysophospholipids (LPs), lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), are known to affect various cellular events. Their actions are mediated by binding to at least ten bona fide high-affinity G protein-coupled receptors referred to as LPA1-5 and S1P1-5. These LPs are expressed throughout the body and are involved in a range of biological activities including normal development, as well as functioning in most organ systems. A growing number of biological functions have been uncovered in vivo using single- or multiple-null mice for each LP receptor. This review will focus on findings from in vivo as well as in vitro studies using genetic null mice for the LP receptors, LPA1,2,3 and S1P1,2,3,5, and for the LP producing enzymes, autotaxin and sphingosine kinase 1/2.
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Affiliation(s)
- Ji Woong Choi
- Department of Molecular Biology, Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, 10550 North Torrey Pines Rd., ICND-118, La Jolla, CA 92037, USA
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Matas-Rico E, García-Diaz B, Llebrez-Zayas P, López-Barroso D, Santín L, Pedraza C, Smith-Fernández A, Fernández-Llebrez P, Tellez T, Redondo M, Chun J, De Fonseca FR, Estivill-Torrús G. Deletion of lysophosphatidic acid receptor LPA1 reduces neurogenesis in the mouse dentate gyrus. Mol Cell Neurosci 2008; 39:342-55. [PMID: 18708146 DOI: 10.1016/j.mcn.2008.07.014] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 07/10/2008] [Accepted: 07/11/2008] [Indexed: 10/21/2022] Open
Abstract
Neurogenesis persists in certain regions of the adult brain including the subgranular zone of the hippocampal dentate gyrus wherein its regulation is essential, particularly in relation to learning, stress and modulation of mood. Lysophosphatidic acid (LPA) is an extracellular signaling phospholipid with important neural regulatory properties mediated by specific G protein-coupled receptors, LPA(1-5). LPA(1) is highly expressed in the developing neurogenic ventricular zone wherein it is required for normal embryonic neurogenesis, and, by extension may play a role in adult neurogenesis as well. By means of the analyses of a variant of the original LPA(1)-null mutant mouse, termed the Malaga variant or "maLPA(1)-null," which has recently been reported to have defective neurogenesis within the embryonic cerebral cortex, we report here a role for LPA(1) in adult hippocampal neurogenesis. Proliferation, differentiation and survival of newly formed neurons are defective in the absence of LPA(1) under normal conditions and following exposure to enriched environment and voluntary exercise. Furthermore, analysis of trophic factors in maLPA(1)-null mice demonstrated alterations in brain-derived neurotrophic factor and insulin growth factor 1 levels after enrichment and exercise. Morphological analyses of doublecortin positive cells revealed the anomalous prevalence of bipolar cells in the subgranular zone, supporting the operation of LPA(1) signaling pathways in normal proliferation, maturation and differentiation of neuronal precursors.
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Affiliation(s)
- Elisa Matas-Rico
- Unidad de Investigación, Fundación IMABIS, Hospital Regional Universitario Carlos Haya, Málaga, Spain
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Chun J, Blaschke AJ. Identification of neural programmed cell death through the detection of DNA fragmentation in situ and by PCR. ACTA ACUST UNITED AC 2008; Chapter 3:Unit 3.8. [PMID: 18428472 DOI: 10.1002/0471142301.ns0308s00] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A universal feature in the development of multicellular organisms is a physiological form of cell death called programmed cell death (PCD). A subset of PCD is apoptosis, which is defined by characteristic morphological changes and genomic DNA fragmentation producing what are referred to as nucleosomal ladders. To understand how PCD operates in a developing tissue or in a tissue following an experimental procedure, dying cells must be identified in relation to their surviving neighbors. One way to accomplish this is to visualize fragmented DNA in situ, in conjunction with gel electrophoresis of isolated DNA to visualize the nucleosomal ladders associated with apoptosis. Two approaches are presented in this unit: in situ end-labeling plus (ISEL+), a technique to identify dying cells in tissue sections or cell cultures of central nervous system (CNS) tissue (optimized for embryonic samples); and the use of ligation-mediated polymerase chain reaction (LMPCR) to identify nucleosomal ladders from intact tissues. Also included are procedures for preparing thymocyte cell cultures for use as controls in the ISEL+ procedure and for isolating genomic DNA for LMPCR.
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Affiliation(s)
- J Chun
- University of California at San Diego School of Medicine, La Jolla, California, USA
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74
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Ye X. Lysophospholipid signaling in the function and pathology of the reproductive system. Hum Reprod Update 2008; 14:519-36. [PMID: 18562325 DOI: 10.1093/humupd/dmn023] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are two prominent signaling lysophospholipids (LPs) exerting their functions through a group of G protein-coupled receptors (GPCRs). This review covers current knowledge of the LP signaling in the function and pathology of the reproductive system. METHODS PubMed was searched up to May 2008 for papers on lysophospholipids/LPA/S1P/LPC/SPC in combination with each part of the reproductive system, such as testis/ovary/uterus. RESULTS LPA and SIP are found in significant amounts in serum and other biological fluids. To date, 10 LP receptors have been identified, including LPA(1-5) and S1P(1-5). In vitro and in vivo studies from the past three decades have demonstrated or suggested the physiological functions of LP signaling in reproduction, such as spermatogenesis, male sexual function, ovarian function, fertilization, early embryo development, embryo spacing, implantation, decidualization, pregnancy maintenance and parturition, as well as pathological roles in ovary, cervix, mammary gland and prostate cancers. CONCLUSIONS Receptor knock-out and other studies indicate tissue-specific and receptor-specific functions of LP signaling in reproduction. More comprehensive studies are required to define mechanisms of LP signaling and explore the potential use as a therapeutic target.
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Affiliation(s)
- Xiaoqin Ye
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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75
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Nadra K, de Preux Charles AS, Médard JJ, Hendriks WT, Han GS, Grès S, Carman GM, Saulnier-Blache JS, Verheijen MH, Chrast R. Phosphatidic acid mediates demyelination in Lpin1 mutant mice. Genes Dev 2008; 22:1647-61. [PMID: 18559480 PMCID: PMC2428062 DOI: 10.1101/gad.1638008] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 04/18/2008] [Indexed: 11/25/2022]
Abstract
Lipids play crucial roles in many aspects of glial cell biology, affecting processes ranging from myelin membrane biosynthesis to axo-glial interactions. In order to study the role of lipid metabolism in myelinating glial cells, we specifically deleted in Schwann cells the Lpin1 gene, which encodes the Mg2+-dependent phosphatidate phosphatase (PAP1) enzyme necessary for normal triacylglycerol biosynthesis. The affected animals developed pronounced peripheral neuropathy characterized by myelin degradation, Schwann cell dedifferentiation and proliferation, and a reduction in nerve conduction velocity. The observed demyelination is mediated by endoneurial accumulation of the substrate of the PAP1 enzyme, phosphatidic acid (PA). In addition, we show that PA is a potent activator of the MEK-Erk pathway in Schwann cells, and that this activation is required for PA-induced demyelination. Our results therefore reveal a surprising role for PA in Schwann cell fate determination and provide evidence of a direct link between diseases affecting lipid metabolism and abnormal Schwann cell function.
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Affiliation(s)
- Karim Nadra
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
| | - Anne-Sophie de Preux Charles
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
- Graduate Program in Neurosciences, University of Lausanne, 1015 Lausanne, Switzerland
| | - Jean-Jacques Médard
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
| | - William T. Hendriks
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Gil-Soo Han
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, USA
| | - Sandra Grès
- INSERM, U858/I2MR, Department of Metabolism and Obesity, BP 84225, 31432 Toulouse Cedex 4, France
| | - George M. Carman
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, USA
| | | | - Mark H.G. Verheijen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Roman Chrast
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
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Ye X, Skinner MK, Kennedy G, Chun J. Age-dependent loss of sperm production in mice via impaired lysophosphatidic acid signaling. Biol Reprod 2008; 79:328-36. [PMID: 18448840 DOI: 10.1095/biolreprod.108.068783] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Approximately half of all infertility cases can be attributed to male reproductive dysfunction for which low sperm count is a major contributing factor. The current study identified receptor-mediated lysophosphatidic acid (LPA) signaling as a new molecular component influencing male fertility. LPA is a small signaling phospholipid, the effects of which are mediated through at least five G protein-coupled receptors, named LPA 1-5. LPA1/2/3, but not LPA4/5, show high expression in mouse testis. Mice deficient in LPA1/2/3 showed a testosterone-independent reduction of mating activity and sperm production, with an increased prevalence of azoospermia in aging animals. A significant increase of germ cell apoptosis also was observed in testes. Germ cell apoptosis led to a reduction in germ cell proliferation. These data demonstrate a novel in vivo function for LPA signaling as a germ cell survival factor during spermatogenesis.
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Affiliation(s)
- Xiaoqin Ye
- Department of Molecular Biology, The Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, La Jolla, California 92037, USA
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77
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Ueda H. Peripheral mechanisms of neuropathic pain - involvement of lysophosphatidic acid receptor-mediated demyelination. Mol Pain 2008; 4:11. [PMID: 18377664 PMCID: PMC2365930 DOI: 10.1186/1744-8069-4-11] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 04/01/2008] [Indexed: 01/23/2023] Open
Abstract
Recent advances in pain research provide a clear picture for the molecular mechanisms of acute pain; substantial information concerning plasticity that occurs during neuropathic pain has also become available. The peripheral mechanisms responsible for neuropathic pain are found in the altered gene/protein expression of primary sensory neurons. With damage to peripheral sensory fibers, a variety of changes in pain-related gene expression take place in dorsal root ganglion neurons. These changes, or plasticity, might underlie unique neuropathic pain-specific phenotype modifications - decreased unmyelinated-fiber functions, but increased myelinated A-fiber functions. Another characteristic change is observed in allodynia, the functional change of tactile to nociceptive perception. Throughout a series of studies, using novel nociceptive tests to characterize sensory-fiber or pain modality-specific nociceptive behaviors, it was demonstrated that communication between innocuous and noxious sensory fibers might play a role in allodynia mechanisms. Because neuropathic pain in peripheral and central demyelinating diseases develops as a result of aberrant myelination in experimental animals, demyelination seems to be a key mechanism of plasticity in neuropathic pain. More recently, we discovered that lysophosphatidic acid receptor activation initiates neuropathic pain, as well as possible peripheral mechanism of demyelination after nerve injury. These results lead to further hypotheses of physical communication between innocuous Abeta- and noxious C- or Adelta-fibers to influence the molecular mechanisms of allodynia.
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Affiliation(s)
- Hiroshi Ueda
- Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
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78
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Spohr TCS, de Sampaio E Spohr TC, Choi JW, Gardell SE, Herr DR, Rehen SK, Gomes FCA, Chun J. Lysophosphatidic acid receptor-dependent secondary effects via astrocytes promote neuronal differentiation. J Biol Chem 2008; 283:7470-9. [PMID: 18198181 PMCID: PMC2276323 DOI: 10.1074/jbc.m707758200] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 12/20/2007] [Indexed: 12/11/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a simple phospholipid derived from cell membranes that has extracellular signaling properties mediated by at least five G protein-coupled receptors referred to as LPA(1)-LPA(5). In the nervous system, receptor-mediated LPA signaling has been demonstrated to influence a range of cellular processes; however, an unaddressed aspect of LPA signaling is its potential to produce specific secondary effects, whereby LPA receptor-expressing cells exposed to, or "primed," by LPA may then act on other cells via distinct, yet LPA-initiated, mechanisms. In the present study, we examined cerebral cortical astrocytes as possible indirect mediators of the effects of LPA on developing cortical neurons. Cultured astrocytes express at least four LPA receptor subtypes, known as LPA(1)-LPA(4). Cerebral cortical astrocytes primed by LPA exposure were found to increase neuronal differentiation of cortical progenitor cells. Treatment of unprimed astrocyte-progenitor cocultures with conditioned medium derived from LPA-primed astrocytes yielded similar results, suggesting the involvement of an astrocyte-derived soluble factor induced by LPA. At least two LPA receptor subtypes are involved in LPA priming, since the priming effect was lost in astrocytes derived from LPA receptor double-null mice (LPA(1)((-/-))/LPA(2)((-/-))). Moreover, the loss of LPA-dependent differentiation in receptor double-null astrocytes could be rescued by retrovirally transduced expression of a single deleted receptor. These data demonstrate that receptor-mediated LPA signaling in astrocytes can induce LPA-dependent, indirect effects on neuronal differentiation.
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Affiliation(s)
- Tânia Cristina Sampaio Spohr
- Departamento de Anatomia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21949-590 Rio de Janeiro RJ, Brazil
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79
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Hu X, Mendoza FJ, Sun J, Banerji V, Johnston JB, Gibson SB. Lysophosphatidic acid (LPA) induces the expression of VEGF leading to protection against apoptosis in B-cell derived malignancies. Cell Signal 2008; 20:1198-208. [PMID: 18396013 DOI: 10.1016/j.cellsig.2008.02.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 02/14/2008] [Accepted: 02/15/2008] [Indexed: 01/01/2023]
Abstract
Vascular endothelial growth factor (VEGF) is a survival and angiogenesis factor that is a target for therapy in a variety of cancers. In many hematological malignancies, VEGF production is increased leading to cell survival responses. Herein, we demonstrate that lysophosphatidic acid (LPA) induces mRNA expression of VEGF in the multiple myeloma cell line, U266, the Burkitt's lymphoma cell line, BJAB, and the chronic lymphocytic leukemia (CLL)-like cell line, I-83. This increase in mRNA levels of VEGF corresponded with increased luciferase activity of the VEGF promoter in BJAB and I-83 cells and increased protein levels in I-83 cells. Secretion of VEGF was also increased in these cells following LPA treatment. LPA treatment also caused the activation of both VEGFR1 and VEGFR2. The increase in VEGF expression by LPA is mediated by the activation of c-Jun N-terminal Kinase (JNK) and transcription factor NFkappaB since blocking JNK or NFkappaB activation inhibited LPA induced VEGF expression. Furthermore, we have demonstrated that LPA protects cells from apoptosis and blocking activation of both VEGFR1 and VEGFR2 using a VEGF receptor kinase inhibitor prevented LPA survival responses. Knocking down expression of VEGFR1 and inhibiting activation of NFkappaB and JNK also blocked LPA induced protection against apoptosis. Taken together, this indicates that LPA contributes to VEGF production in B cell malignancies leading to cell survival.
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Affiliation(s)
- Xiaojie Hu
- Manitoba Institute of Cell Biology, Winnipeg, MB, Canada
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Murph MM, Hurst-Kennedy J, Newton V, Brindley DN, Radhakrishna H. Lysophosphatidic acid decreases the nuclear localization and cellular abundance of the p53 tumor suppressor in A549 lung carcinoma cells. Mol Cancer Res 2008; 5:1201-11. [PMID: 18025263 DOI: 10.1158/1541-7786.mcr-06-0338] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Lysophosphatidic acid (LPA) is a bioactive lipid that promotes cancer cell proliferation and motility through activation of cell surface G protein-coupled receptors. Here, we provide the first evidence that LPA reduces the cellular abundance of the tumor suppressor p53 in A549 lung carcinoma cells, which express endogenous LPA receptors. The LPA effect depends on increased proteasomal degradation of p53 and it results in a corresponding decrease in p53-mediated transcription. Inhibition of phosphatidylinositol 3-kinase protected cells from the LPA-induced reduction of p53, which implicates this signaling pathway in the mechanism of LPA-induced loss of p53. LPA partially protected A549 cells from actinomycin D induction of both apoptosis and increased p53 abundance. Expression of LPA(1), LPA(2), and LPA(3) receptors in HepG2 hepatoma cells, which normally do not respond to LPA, also decreased p53 expression and p53-dependent transcription. In contrast, neither inactive LPA(1) (R124A) nor another G(i)-coupled receptor, the M(2) muscarinic acetylcholine receptor, reduced p53-dependent transcription in HepG2 cells. These results identify p53 as a target of LPA action and provide a new dimension for understanding how LPA stimulates cancer cell division, protects against apoptosis, and thereby promotes tumor progression.
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Affiliation(s)
- Mandi M Murph
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia , USA
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81
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Caravatta L, Sancilio S, di Giacomo V, Rana R, Cataldi A, Di Pietro R. PI3-K/Akt-dependent activation of cAMP-response element-binding (CREB) protein in Jurkat T leukemia cells treated with TRAIL. J Cell Physiol 2008; 214:192-200. [PMID: 17579344 DOI: 10.1002/jcp.21186] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We recently demonstrated the activation of phosphatidylinositol 3-kinase (PI3-K/Akt) survival pathway in Jurkat T leukemia cells known for their sensitivity to the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)/Apo2L cytotoxic action. The present investigation was done to elucidate the role of cAMP-response element-binding (CREB) protein in this system. Jurkat T cells were treated with 100-1,000 ng/ml TRAIL for time intervals up to 24 h in the presence or absence of selective pharmacologic inhibitors of PI3-K/Akt (LY294002) or p38 MAPK (SB253580) pathways. Upon TRAIL treatment, a dose-dependent increase in the percentage of apoptotic cells as well as in caspase-3 activity was observed. A further enhancement of apoptotic cell death was obtained with the use of CREB1 siRNA technology, as demonstrated by flow cytometry. Western blot analysis showed a high constitutive level of CREB phosphorylation at Ser(133) in Jurkat T cells under normal serum culture conditions. Under low serum culture conditions, an early (within 1 h) and transient increase in CREB phosphorylation was detected in response to both TRAIL doses and reduced upon pre-treatment with LY294002 or SB253580, demonstrating the PI3-K/Akt- and p38 MAPK-dependency of this effect. The parallel analysis in immune fluorescence demonstrated the nuclear translocation of the phosphorylated form upon treatment with 100 ng/ml TRAIL, whereas the immune labeling was mainly detectable in the cytoplasm compartment upon the higher more cytotoxic dose. These results let us hypothesize that CREB activation can be an important player in the complex cross-talk among pro- and anti-apoptotic pathways in this peculiar cell model.
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Affiliation(s)
- Luciana Caravatta
- Dipartimento di Biomorfologia, Università G. d'Annunzio, Chieti-Pescara, Italy
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82
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Shan L, Li S, Jaffe K, Davis L. Quantitative determination of cyclic phosphatidic acid in human serum by LC/ESI/MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2007; 862:161-7. [PMID: 18155973 DOI: 10.1016/j.jchromb.2007.12.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 10/23/2007] [Accepted: 12/01/2007] [Indexed: 02/04/2023]
Abstract
An LC/ESI/MS/MS method for cyclic phosphatidic acid (cPA) quantification in serum is established in the present report. The limit of quantitation of the assay reaches low nanomolar level in human serum and the CV% are within 10%. Using this method, we successfully quantify the levels of two cPA species, 16:0 and 18:1, in human serum. We find that the concentrations of 16:0 cPA in the serum of normal subjects and post-surgery ovarian cancer patients are significantly higher than its corresponding concentration in pre-surgery ovarian cancer patients, supporting the observation that cPA has anti-cancer activity. Another discovery is that the addition of strong acids (such as hydrochloric acid) in human serum may lead to the production of artificial cPA. Therefore, strong acids should be avoided in the extraction of cPA present in a complex matrix. Based on this observation, a new lipid extraction method was developed and used to extract cPA. The extraction recovery is close to 80%, guaranteeing an accurate quantification of cPA by LC/ESI/MS/MS can be performed.
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Affiliation(s)
- Lian Shan
- Frantz BioMarkers LLC, 7740 Metric Drive, Mentor, OH 44060, USA.
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83
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A lysophosphatidic acid receptor lacking the PDZ-binding domain is constitutively active and stimulates cell proliferation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1783:748-59. [PMID: 18157949 DOI: 10.1016/j.bbamcr.2007.11.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Revised: 11/13/2007] [Accepted: 11/28/2007] [Indexed: 11/22/2022]
Abstract
Lysophosphatidic acid (LPA) is an extracellular signaling lipid that regulates cell proliferation, survival, and motility of normal and cancer cells. These effects are produced through G protein-coupled LPA receptors, LPA(1) to LPA(5). We generated an LPA(1) mutant lacking the SerValVal sequence of the C-terminal PDZ-binding domain to examine the role of this domain in intracellular signaling and other cellular functions. B103 neuroblastoma cells expressing the mutant LPA(1) showed rapid cell proliferation and tended to form colonies under serum-free conditions. The enhanced cell proliferation of the mutant cells was inhibited by exogenous expression of the plasmids inhibiting G proteins including G(betagamma), G(alphai) and G(alphaq) or G(alpha12/13), or treatment with pertussis toxin, phosphoinositide 3-kinase (PI3K) inhibitors or a Rho inhibitor. We confirmed that the PI3K-Akt and Rho pathways were intrinsically activated in mutant cells by detecting increases in phosphorylated Akt in western blot analyses or by directly measuring Rho activity. Interestingly, expression of the mutant LPA(1) in non-tumor mouse fibroblasts induced colony formation in a clonogenic soft agar assay, indicating that oncogenic pathways were activated. Taken together, these observations suggest that the mutant LPA(1) constitutively activates the G protein signaling leading to PI3K-Akt and Rho pathways, resulting in enhanced cell proliferation.
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Avendaño-Vázquez SE, Cabrera-Wrooman A, Colín-Santana CC, García-Sáinz JA. Lysophosphatidic acid LPA1 receptor close-up. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/sita.200700138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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85
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Maruta T, Yanagita T, Matsuo K, Uezono Y, Satoh S, Nemoto T, Yoshikawa N, Kobayashi H, Takasaki M, Wada A. Lysophosphatidic acid-LPA1 receptor-Rho-Rho kinase-induced up-regulation of Nav1.7 sodium channel mRNA and protein in adrenal chromaffin cells: enhancement of 22Na+ influx, 45Ca2+ influx and catecholamine secretion. J Neurochem 2007; 105:401-12. [PMID: 18036192 DOI: 10.1111/j.1471-4159.2007.05143.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cultured bovine adrenal chromaffin cells, chronic (> or = 24 h) treatment with lysophosphatidic acid (LPA) augmented veratridine-induced 22Na+ influx via Na(v)1.7 by approximately 22% (EC(50) = 1 nmol/L), without changing nicotine-induced 22Na+ influx via nicotinic receptor-associated channel. LPA enhanced veratridine (but not nicotine)-induced 45Ca2+ influx via voltage-dependent calcium channel and catecholamine secretion. LPA shifted concentration-response curve of veratridine for 22Na+ influx upward, without altering the EC(50) of veratridine. Ptychodiscus brevis toxin-3 allosterically enhanced veratridine-induced 22Na+ influx by twofold in non-treated and LPA-treated cells. Whole-cell patch-clamp analysis showed that peak Na+ current amplitude was greater by 39% in LPA (100 nmol/L for 36 h)-treated cells; however, I-V curve and steady-state inactivation/activation curves were comparable between non-treated and LPA-treated cells. LPA treatment (> or = 24 h) increased cell surface [3H]saxitoxin binding by approximately 28%, without altering the K(d) value; the increase was prevented by cycloheximide, actinomycin D, or Ki16425, dioctylglycerol pyrophosphate 8:0 (two inhibitors of LPA(1) and LPA3 receptors), or botulinum toxin C3 (Rho inhibitor), Y27632 (Rho kinase inhibitor), consistent with LPA(1) receptor expression in adrenal chromaffin cells. LPA raised Nav1.7 mRNA level by approximately 37%. Thus, LPA-LPA(1) receptor-Rho/Rho kinase pathway up-regulated cell surface Nav1.7 and Nav1.7 mRNA levels, enhancing veratridine-induced Ca2+ influx and catecholamine secretion.
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Affiliation(s)
- Toyoaki Maruta
- Departments of Pharmacology, and Anesthesiology, Miyazaki Medical College, University of Miyazaki, Miyazaki, Japan
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86
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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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Chen J, Baydoun AR, Xu R, Deng L, Liu X, Zhu W, Shi L, Cong X, Hu S, Chen X. Lysophosphatidic acid protects mesenchymal stem cells against hypoxia and serum deprivation-induced apoptosis. Stem Cells 2007; 26:135-45. [PMID: 17932426 DOI: 10.1634/stemcells.2007-0098] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bone marrow-derived mesenchymal stem cells (MSCs) have shown great promise for cardiac repair. However, poor viability of transplanted MSCs within the ischemic heart has limited their therapeutic potential. Our previous studies have documented that hypoxia and serum deprivation (hypoxia/SD), induced MSCs apoptosis through the mitochondrial apoptotic pathway. Since serum lysophosphatidic acid (LPA) levels are known to be significantly elevated after acute myocardial infarction and that LPA enhanced survival of other cell systems, we embarked on determining whether LPA protects MSCs against hypoxia/SD-induced apoptosis. We have also investigated the potential mechanism(s) that may mediate such actions of LPA. All experiments were carried out on rat bone marrow MSCs. Apoptosis was induced by exposure of cells to hypoxia/SD in a sealed GENbox hypoxic chamber. Effects of LPA were investigated in the absence and presence of inhibitors that target either G(i)proteins, the mitogen activated protein kinases ERK1/2, or phosphoinositide 3-kinase (PI3K). The data obtained showed that hypoxia/SD-induced apoptosis was significantly attenuated by LPA through Gi-coupled LPA(1) receptors linked to the downstream ERK1/2 and PI3K/Akt signaling pathways that function in parallel. Additional studies have demonstrated that hypoxia/SD-induced activation of mitochondrial dysfunction was virtually abolished by LPA treatment and that inhibition of the LPA(1) receptor, Gi proteins, the PI3K/Akt pathway, or ERKs effectively reversed this protective action of LPA. Taken together, our findings indicate that LPA is a novel, potent survival factor for MSCs and this may prove to be of considerable therapeutic significance in terms of exploiting MSC-based therapy in the infracted myocardium.
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Affiliation(s)
- Jinghai Chen
- Research Center for Cardiovascular Regenerative Medicine, The Ministry of Health of China, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
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88
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Salcedo M, Cuevas C, Alonso JL, Otero G, Faircloth G, Fernandez-Sousa JM, Avila J, Wandosell F. The marine sphingolipid-derived compound ES 285 triggers an atypical cell death pathway. Apoptosis 2007; 12:395-409. [PMID: 17191124 DOI: 10.1007/s10495-006-0573-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The isolation of new molecules from marine sources opens the door to their possible therapeutic use against tumors and other pathological conditions. Indeed, we recently defined the cytotoxicity of ES 285, obtained from the clam Mactromeris polynima, and its affects on the cells microfilament but not the microtubule network. Considering the analogy between ES 285 and sphingosine-related lipids, we wondered whether ES 285 might affect the activity of PKC at the intracellular level. While we anticipated that ES 285 might inhibit PKC, it turns out that in contrast it serves to activate PKC at the cellular level. Indeed, like other sphingosine-related lipids, ES 285 induces the phosphorylation of MARCKS. Additionally, we further examined the cytotoxicity of ES 285 to elucidate the molecular mechanisms through which this compound triggers apoptosis. When the influence of ES 285 on "cell death markers" was assessed, it became clear that ES285 activates caspase 3 and 12, and that it modified the phosphorylation of p53. In contrast, ES 285 does not affect other pathways widely implicated in regulating cell survival/apoptosis, such as JNK, Erks or Akt. Thus, these data suggest that ES 285-triggers an atypical cell death program when compared to other sphingosine-dependent apoptosis pathways.
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Affiliation(s)
- M Salcedo
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049, Madrid, Spain
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89
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Saravanan K, Büssow H, Weiler N, Gieselmann V, Franken S. A spontaneously immortalized Schwann cell line to study the molecular aspects of metachromatic leukodystrophy. J Neurosci Methods 2007; 161:223-33. [PMID: 17204333 DOI: 10.1016/j.jneumeth.2006.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 11/16/2006] [Accepted: 11/19/2006] [Indexed: 11/29/2022]
Abstract
The arylsulfatase A (ASA)-deficient mouse is a murine model of human metachromatic leukodystrophy (MLD) caused by a genetic defect in the ASA gene. Deficiency of ASA causes accumulation of cerebroside-3-sulfate (sulfatide) in visceral organs and in the central and peripheral nervous system, which subsequently causes demyelination in these areas. To investigate further the cellular pathomechanism of MLD, we established spontaneously immortalized Schwann cell lines from ASA-deficient mice. Cells showed marked sulfatide storage in the late endosomal/lysosomal compartment. This sulfatide accumulation can be further increased by external treatment with sulfatide using a lipid based transfection reagent as a cargo. The accumulated sulfatide was degraded in response to ASA treatment and first examination revealed that alteration on the molecular level found in ASA-deficient mice can also be observed in the presented cell culture model. Hence, these cells could be a suitable model to study MLD at a molecular level.
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Affiliation(s)
- Karumbayaram Saravanan
- Institut für Physiologische Chemie, Rheinische Friedrich-Wilhelms-Universität, Nussallee 11, 53115 Bonn, Germany
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90
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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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91
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Zheng DM, Kitamura T, Ikejima K, Enomoto N, Yamashina S, Suzuki S, Takei Y, Sato N. Sphingosine 1-phosphate protects rat liver sinusoidal endothelial cells from ethanol-induced apoptosis: Role of intracellular calcium and nitric oxide. Hepatology 2006; 44:1278-87. [PMID: 17058266 DOI: 10.1002/hep.21384] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In alcoholic liver disease, ethanol-induced damage to sinusoidal endothelial cells (SECs) appears to be important in the progression of liver damage. However, little is known about the mechanisms responsible for protection of SECs against ethanol-induced injury. To elucidate the role of sphingosine 1-phosphate (S1P), which is stored in platelets and may be released from them on their activation, we investigated the effect of S1P on rat liver SECs in primary culture. Pretreatment of cells with 1 mumol/L S1P attenuated ethanol-induced apoptosis. Electron microscopy confirmed this protective effect of S1P on damaged SECs in liver tissues after perfusion of ethanol. In the absence of ethanol, S1P increased DNA synthesis as determined via incorporation of bromodeoxyuridine. S1P also ameliorated the decreased DNA synthesis of cells induced by ethanol. Addition of S1P to cells induced an increase in intracellular calcium concentrations and NO production in cells. Western blotting revealed that S1P significantly induced the activation of endothelial NO synthase (eNOS), but not Akt, and that S1P-induced activation of eNOS was blocked by trifluoperazine, a calmodulin inhibitor. Furthermore, N(G)-nitro-L-arginine methyl ester, a NO synthase inhibitor, cancelled the effect of S1P on DNA synthesis, apoptosis, and NO production in vitro as well as the protective effect of S1P on cell damage in situ. In conclusion, the biological effect of S1P is at least partially mediated by Ca(2+)-sensitive eNOS activation and subsequent NO formation; extracellular S1P could contribute to sinusoidal protection and remodeling in alcoholic liver injury.
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Affiliation(s)
- Dong-Mei Zheng
- Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan
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92
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Savitz SI, Dhallu MS, Malhotra S, Mammis A, Ocava LC, Rosenbaum PS, Rosenbaum DM. EDG receptors as a potential therapeutic target in retinal ischemia-reperfusion injury. Brain Res 2006; 1118:168-75. [PMID: 17026968 DOI: 10.1016/j.brainres.2006.05.060] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 05/17/2006] [Accepted: 05/19/2006] [Indexed: 11/21/2022]
Abstract
LPA (lysophosphatidic acid) specific endothelial differentiation gene (EDG) receptors have been implicated in various anti-apoptotic pathways. Ischemia of the brain and retina causes neuronal apoptosis, which raises the possibility that EDG receptors participate in anti-apoptotic signaling in ischemic injury. We examined the expression of EDG receptors in a model of retinal ischemia-reperfusion injury and also tested LXR-1035, a novel analogue of LPA, in the rat following global retinal ischemic injury. Rats were subjected to 45 or 60 min of raised intraocular pressure. Animals were sacrificed at 24 h post-ischemia and retinal tissue was stained for EDG receptors. In separate experiments, animals were randomized to receive LXR or saline vehicle by intravitreal injection 24 h prior to ischemia. The degree of retinal damage was assessed morphologically by measuring the thickness of the inner retinal layers as well as functionally by electroretinography (ERG). We found that the normal retina has a baseline expression of the LPA receptors, EDG-2 and EDG-4, which are significantly upregulated in the inner layers in response to ischemia. Animals pretreated with LXR-1035 had dose-dependent, significant reductions in histopathologic damage and significant improvement in functional deficits compared with corresponding vehicle-controls, after 45 and 60 min of ischemia. These results suggest that LPA receptor signaling may play an important role in neuroprotection in retinal ischemia-reperfusion injury.
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Affiliation(s)
- Sean I Savitz
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, USA.
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93
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Li Q, Ping P, Jiang H, Liu K. Nerve conduit filled with GDNF gene-modified Schwann cells enhances regeneration of the peripheral nerve. Microsurgery 2006; 26:116-21. [PMID: 16538638 DOI: 10.1002/micr.20192] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A recombinant retrovirus vector containing the glial cell line-derived neurotrophic factor (GDNF) gene was constructed and transfected into Schwann cells (SCs) to investigate the possibility of GDNF transfection and functional expression of transfected SCs, including GDNF secretion and its mRNA expression. We found that transfection of the GDNF gene into SCs led to significantly enhanced expression of GDNF mRNA. The rate of GDNF secretion by GDNF-SCs was also increased. Functionally, more surviving motoneurons were seen when they were cocultured in GDNF-SC-conditioned medium than when they were in normal SC-conditioned medium. When bridging a rat sciatic nerve defect with a conduit filled with GDNF-transfected SCs, nerve regeneration was better than that of the control. In conclusion, transfection of SCs with the GDNF gene could enhance SC function. Application of genetically modified SCs could be a better way to promote nerve regeneration.
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Affiliation(s)
- Qingfeng Li
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Second Medical University, Shanghai, P.R. China
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94
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Kobashi H, Yaoi T, Oda R, Okajima S, Fujiwara H, Kubo T, Fushiki S. Lysophospholipid receptors are differentially expressed in rat terminal Schwann cells, as revealed by a single cell rt-PCR and in situ hybridization. Acta Histochem Cytochem 2006; 39:55-60. [PMID: 17375210 PMCID: PMC1828080 DOI: 10.1267/ahc.06002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Accepted: 03/03/2006] [Indexed: 11/22/2022] Open
Abstract
Terminal Schwann cells (TSCs) that cover motor neuron terminals, are known to play an important role in maintaining neuromuscular junctions, as well as in the repair process after nerve injury. However, the molecular characteristics of TSCs remain unknown, because of the difficulties in analyzing them due to their paucity. By using our previously reported method of selectively and efficiently collecting TSCs, we have analyzed the difference in expression patterns of lysophospholipid (LPL) receptor genes (LPA1, LPA2, LPA3, S1P1, S1P2, S1P3, S1P4, and S1P5) between TSCs and myelinating Schwann cells (MSCs). LPL, which includes lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), is the bioactive lipid that induces a myriad of cellular responses through specific members of G-protein coupled receptors for LPA. It turned out that LPA3 was expressed only in TSCs, whereas S1P1 was expressed in TSCs and skeletal muscle, but not in MSCs. Other types of LPL receptor genes, including LPA1, S1P2, S1P3, S1P4, were expressed in both types of Schwann cells. None of the LPL receptor gene family showed MSCs-specific expression.
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Affiliation(s)
- Hiroaki Kobashi
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine,Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
- Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
| | - Takeshi Yaoi
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine,Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
| | - Ryo Oda
- Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
| | - Seiichiro Okajima
- Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
| | - Hiroyoshi Fujiwara
- Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
| | - Toshikazu Kubo
- Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
| | - Shinji Fushiki
- Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine,Kawaramachi-Hirokoji, Kyoto 602–8566, Japan
- Correspondence to: Shinji Fushiki, Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602–8566, Japan. E-mail:
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Dennis J, Nogaroli L, Fuss B. Phosphodiesterase-Ialpha/autotaxin (PD-Ialpha/ATX): a multifunctional protein involved in central nervous system development and disease. J Neurosci Res 2006; 82:737-42. [PMID: 16267828 DOI: 10.1002/jnr.20686] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Phosphodiesterase-Ialpha/autotaxin (PD-Ialpha/ATX) was originally identified as a cell-motility-stimulating factor secreted by a variety of tumor cells. Thus, studies related to its potential functional roles have traditionally focused on tumorigenesis. PD-Ialpha/ATX's catalytic activity, initially defined as nucleotide pyrophosphatase/phosphodiesterase, was soon recognized as being necessary for its tumor cell-motility-stimulating activity. However, only the discovery of PD-Ialpha/ATX's identity with lysophospholipase D, an extracellular enzyme that converts lysophosphatidylcholine into lysophosphatidic acid (LPA) and potentially sphingosylphosphoryl choline into sphingosine 1-phosphate (S1P), revealed the actual effectors responsible for PD-Ialpha/ATX's ascribed motogenic functions, i.e., its catalytic products. PD-Ialpha/ATX has also been detected during normal development in a number of tissues, in particular, the central nervous system (CNS), where expression levels are high. Similar to tumor cells, PD-Ialpha/ATX-expressing CNS cells secrete catalytically active PD-Ialpha/ATX into the extracellular environment. Thus, it appears reasonable to assume that PD-Ialpha/ATX's CNS-related functions are mediated via lysophospholipid, LPA and potentially S1P, signaling. However, recent studies identified PD-Ialpha/ATX as a matricellular protein involved in the modulation of oligodendrocyte-extracellular matrix interactions and oligodendrocyte remodeling. This property of PD-Ialpha/ATX was found to be independent of its catalytic activity and to be mediated by a novel functionally active domain. These findings, therefore, uncover PD-Ialpha/ATX, at least in the CNS, as a multifunctional protein able to induce complex signaling cascades via distinct structure-function domains. This Mini-Review describes PD-Ialpha/ATX's multifunctional roles in the CNS and discusses their potential contributions to CNS development and pathology.
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Affiliation(s)
- Jameel Dennis
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, 23298, USA
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96
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Gardell SE, Dubin AE, Chun J. Emerging medicinal roles for lysophospholipid signaling. Trends Mol Med 2006; 12:65-75. [PMID: 16406843 DOI: 10.1016/j.molmed.2005.12.001] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 11/21/2005] [Accepted: 12/09/2005] [Indexed: 02/06/2023]
Abstract
The two lysophospholipids (LPs) lysophosphatidic acid and sphingosine 1-phosphate (S1P) regulate diverse biological processes. Over the past decade, it has become clear that medically relevant LP activities are mediated by specific G protein-coupled receptors, implicating them in the etiology of a growing number of disorders. A new class of LP agonists shows promise for drug therapy: the experimental drug FTY720 is phosphorylated in vivo to produce a potent S1P receptor agonist (FTY720-P) and is currently in Phase III clinical trials for kidney transplantation and Phase II for multiple sclerosis. Recent genetic and pharmacological studies on LP signaling in animal disease models have identified new areas in which interventions in LP signaling might provide novel therapeutic approaches for the treatment of human diseases.
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Affiliation(s)
- Shannon E Gardell
- Department of Molecular Biology, Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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97
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Ueda H. Molecular mechanisms of neuropathic pain–phenotypic switch and initiation mechanisms. Pharmacol Ther 2006; 109:57-77. [PMID: 16023729 DOI: 10.1016/j.pharmthera.2005.06.003] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Accepted: 06/06/2005] [Indexed: 12/29/2022]
Abstract
Many known painkillers are not always effective in the therapy of chronic neuropathic pain manifested by hyperalgesia and tactile allodynia. The mechanisms underlying neuropathic pain appear to be complicated and to differ from acute and inflammatory pain. Recent advances in pain research provide us with a clear picture for the molecular mechanisms of acute pain, and substantial information is available concerning the plasticity that occurs under conditions of neuropathic pain. The most important changes responsible for the mechanisms of neuropathic pain are found in the altered gene/protein expression in primary sensory neurons. After damage to peripheral sensory fibers, up-regulated expression of the Ca(v)alpha(2)delta-(1) channel subunit, the Na(v)1.3 sodium channel, and bradykinin (BK) B1 and capsaicin TRPV1 receptors in myelinated neurons contribute to hyperalgesia; while the down-regulation of the Na(v)1.8 sodium channel, B2 receptor, substance P (SP), and even mu-opioid receptors in unmyelinated neurons is responsible for the phenotypic switch in pain transmission. Clarification of the molecular mechanisms for such complicated plasticity would be extremely valuable when considering the therapeutic design of pain relieving drugs. Although many reports deal with the changes in expression of key molecules related to neuropathic pain, the initiation and the mechanisms that follow remain to be determined. The current study using lysophosphatidic acid (LPA) receptor knockout mice revealed that LPA produced by nerve injury initiates neuropathic pain and demyelination following partial sciatic nerve ligation (PSNL). A single injection of LPA was found to mimic PSNL in terms of neuropathic pain and its underlying mechanisms. This discovery may lead to the subsequent discovery of LPA-induced secondary genes, which would be therapeutic targets for neuropathic pain.
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Affiliation(s)
- Hiroshi Ueda
- Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
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98
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Abstract
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are potent biologically active lipid mediators that exert a wide range of cellular effects through specific G protein-coupled receptors. To date, four LPA receptors and five S1P receptors have been identified. These receptors are expressed in a large number of tissues and cell types, allowing for a wide variety of cellular responses to lysophospholipid signaling, including cell adhesion, cell motility, cytoskeletal changes, proliferation, angiogenesis, process retraction, and cell survival. In addition, recent studies in mice show that specific lysophospholipid receptors are required for proper cardiovascular, immune, respiratory, and reproductive system development and function. Lysophospholipid receptors may also have specific roles in cancer and other diseases. This review will cover identification and expression of the lysophospholipid receptors, as well as receptor signaling properties and function. Additionally, phenotypes of mice deficient for specific lysophospholipid receptors will be discussed to demonstrate how these animals have furthered our understanding of the role lysophospholipids play in normal biology and disease.
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Affiliation(s)
- R Rivera
- The Scripps Research Institute, Department of Molecular Biology, 10550 North Torrey Pines Road, ICND-118, CA 92037, USA
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99
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Jaillard C, Harrison S, Stankoff B, Aigrot MS, Calver AR, Duddy G, Walsh FS, Pangalos MN, Arimura N, Kaibuchi K, Zalc B, Lubetzki C. Edg8/S1P5: an oligodendroglial receptor with dual function on process retraction and cell survival. J Neurosci 2005; 25:1459-69. [PMID: 15703400 PMCID: PMC6726002 DOI: 10.1523/jneurosci.4645-04.2005] [Citation(s) in RCA: 259] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Endothelial differentiation gene (Edg) proteins are G-protein-coupled receptors activated by lysophospholipid mediators: sphingosine-1-phosphate (S1P) or lysophosphatidic acid. We show that in the CNS, expression of Edg8/S1P5, a high-affinity S1P receptor, is restricted to oligodendrocytes and expressed throughout development from the immature stages to the mature myelin-forming cell. S1P activation of Edg8/S1P5 on O4-positive pre-oligodendrocytes induced process retraction via a Rho kinase/collapsin response-mediated protein signaling pathway, whereas no retraction was elicited by S1P on these cells derived from Edg8/S1P5-deficient mice. Edg8/S1P5-mediated process retraction was restricted to immature cells and was no longer observed at later developmental stages. In contrast, S1P activation promoted the survival of mature oligodendrocytes but not of pre-oligodendrocytes. The S1P-induced survival of mature oligodendrocytes was mediated through a pertussis toxin-sensitive, Akt-dependent pathway. Our data demonstrate that Edg8/S1P5 activation on oligodendroglial cells modulates two distinct functional pathways mediating either process retraction or cell survival and that these effects depend on the developmental stage of the cell.
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MESH Headings
- Amino Acid Sequence
- Animals
- Ankyrins/analysis
- Brain/cytology
- Brain/growth & development
- Brain Chemistry
- Cell Differentiation
- Cell Lineage
- Cell Shape/drug effects
- Cell Surface Extensions/drug effects
- Cell Surface Extensions/physiology
- Cell Survival/drug effects
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Cells, Cultured/ultrastructure
- Crosses, Genetic
- Female
- GTP-Binding Protein alpha Subunit, Gi2
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- Intercellular Signaling Peptides and Proteins
- Intracellular Signaling Peptides and Proteins
- Kv1.1 Potassium Channel
- Lysophospholipids/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Sequence Data
- Nerve Tissue Proteins/deficiency
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Nerve Tissue Proteins/physiology
- Oligodendroglia/drug effects
- Oligodendroglia/metabolism
- Oligodendroglia/ultrastructure
- Phosphorylation
- Potassium Channels, Voltage-Gated/analysis
- Protein Processing, Post-Translational
- Protein Serine-Threonine Kinases/metabolism
- Protein Serine-Threonine Kinases/physiology
- Proto-Oncogene Proteins/physiology
- Proto-Oncogene Proteins c-akt
- RNA, Messenger/analysis
- RNA, Small Interfering/pharmacology
- Rats
- Rats, Wistar
- Receptors, Lysosphingolipid/deficiency
- Receptors, Lysosphingolipid/genetics
- Receptors, Lysosphingolipid/physiology
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Sphingosine/analogs & derivatives
- Sphingosine/pharmacology
- rho-Associated Kinases
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Affiliation(s)
- C Jaillard
- Biologie des Interactions Neurones/Glie, Institut National de la Santé et de la Recherche Médicale and Université Pierre et Marie Curie, Unité Mixte de Recherche 711, Hôpital de la Salpêtrière, F-75651 Paris, France
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100
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Matsushita T, Amagai Y, Soga T, Terai K, Obinata M, Hashimoto S. A novel oligodendrocyte cell line OLP6 shows the successive stages of oligodendrocyte development: late progenitor, immature and mature stages. Neuroscience 2005; 136:115-21. [PMID: 16181743 DOI: 10.1016/j.neuroscience.2005.07.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 06/07/2005] [Accepted: 07/06/2005] [Indexed: 11/16/2022]
Abstract
The successive stages of development from oligodendrocyte progenitor to mature oligodendrocyte have been investigated in detail by using stage-specific antibodies. However, no cell lines are available that show stepwise differentiation from oligodendrocyte progenitors to mature oligodendrocytes. Here we show the establishment of an immortalized oligodendrocyte cell line, OLP6, from adult transgenic rats harboring the temperature-sensitive simian virus 40 large T-antigen gene. The OLP6 cells had a fibroblastic morphology and continuously proliferated at 33 degrees C. They displayed growth arrest and multipolar morphology when they were cultured at 39 degrees C. They express the oligodendrocytic markers O4, 2'-3'-cyclic-nucleotide 3'-phosphodiesterase, galactocerebroside and second endothelial differentiation gene receptor-2 at 39 degrees C. The OLP6 cells underwent apoptosis upon serum withdrawal at 39 degrees C. Lysophosphatidic acid inhibited this apoptosis and promoted the expression of myelin basic protein. These results demonstrate that the activation of endothelial differentiation gene receptor-2 exerts anti-apoptosis and myelinogenesis effects on the OLP6 cells. Taken together, the OLP6 cells in the late oligodendrocyte progenitor stage can progress to the immature oligodendrocyte stage by shifting culture temperature. Furthermore, lysophosphatidic acid promoted the maturation of OLP6 cells in the immature oligodendrocyte stage. Such OLP6 cells should provide a potent model system for studying the precise mechanism involved in stepwise differentiation of oligodendrocytes.
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Affiliation(s)
- T Matsushita
- Molecular Medicine Laboratories Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., 21 Miyukigaoka, Tsukuba-shi, Ibaraki, 305-8585 Japan
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