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Implication of Ceramide Kinase/C1P in Cancer Development and Progression. Cancers (Basel) 2022; 14:cancers14010227. [PMID: 35008391 PMCID: PMC8750078 DOI: 10.3390/cancers14010227] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/28/2021] [Accepted: 12/30/2021] [Indexed: 12/28/2022] Open
Abstract
Cancer cells rewire their metabolic programs to favor biological processes that promote cell survival, proliferation, and dissemination. Among this relevant reprogramming, sphingolipid metabolism provides metabolites that can favor or oppose these hallmarks of cancer. The sphingolipid ceramide 1-phosphate (C1P) and the enzyme responsible for its biosynthesis, ceramide kinase (CERK), are well established regulators of cell growth and survival in normal, as well as malignant cells through stress-regulated signaling pathways. This metabolite also promotes cell survival, which has been associated with the feedback regulation of other antitumoral sphingolipids or second messengers. C1P also regulates cancer cell invasion and migration of different types of cancer, including lung, breast, pancreas, prostate, or leukemia cells. More recently, CERK and C1P have been implicated in the control of inflammatory responses. The present review provides an updated view on the important role of CERK/C1P in the regulation of cancer cell growth, survival, and dissemination.
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León Y, Magariños M, Varela-Nieto I. Ceramide Kinase Inhibition Blocks IGF-1-Mediated Survival of Otic Neurosensory Progenitors by Impairing AKT Phosphorylation. Front Cell Dev Biol 2021; 9:678760. [PMID: 34179008 PMCID: PMC8220815 DOI: 10.3389/fcell.2021.678760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 05/12/2021] [Indexed: 11/29/2022] Open
Abstract
Sphingolipids are bioactive lipid components of cell membranes with important signal transduction functions in health and disease. Ceramide is the central building block for sphingolipid biosynthesis and is processed to form structurally and functionally distinct sphingolipids. Ceramide can be phosphorylated by ceramide kinase (CERK) to generate ceramide-1-phosphate, a cytoprotective signaling molecule that has been widely studied in multiple tissues and organs, including the developing otocyst. However, little is known about ceramide kinase regulation during inner ear development. Using chicken otocysts, we show that genes for CERK and other enzymes of ceramide metabolism are expressed during the early stages of inner ear development and that CERK is developmentally regulated at the otic vesicle stage. To explore its role in inner ear morphogenesis, we blocked CERK activity in organotypic cultures of otic vesicles with a specific inhibitor. Inhibition of CERK activity impaired proliferation and promoted apoptosis of epithelial otic progenitors. CERK inhibition also compromised neurogenesis of the acoustic-vestibular ganglion. Insulin-like growth factor-1 (IGF-1) is a key factor for proliferation, survival and differentiation in the chicken otocyst. CERK inhibition decreased IGF-1-induced AKT phosphorylation and blocked IGF-1-induced cell survival. Overall, our data suggest that CERK is activated as a central element in the network of anti-apoptotic pro-survival pathways elicited by IGF-1 during early inner ear development.
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Affiliation(s)
- Yolanda León
- Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain.,Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Magariños
- Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain.,Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.,CIBERER, Unit 761, CIBER, ISCIII, Madrid, Spain
| | - Isabel Varela-Nieto
- Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain.,CIBERER, Unit 761, CIBER, ISCIII, Madrid, Spain
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Varela-Nieto I, Palmero I, Magariños M. Complementary and distinct roles of autophagy, apoptosis and senescence during early inner ear development. Hear Res 2019; 376:86-96. [PMID: 30711386 DOI: 10.1016/j.heares.2019.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 01/13/2019] [Accepted: 01/17/2019] [Indexed: 12/25/2022]
Abstract
The development of the inner ear complex cytoarchitecture and functional geometry requires the exquisite coordination of a variety of cellular processes in a temporal manner. At early stages of inner ear development several rounds of cell proliferation in the otocyst promote the growth of the structure. The apoptotic program is initiated in exceeding cells to adjust cell type numbers. Apoptotic cells are cleared by phagocytic cells that recognize the phosphatidylserine residues exposed in the cell membrane thanks to the energy supplied by autophagy. Specific molecular programs determine hair and supporting cell fate, these populations are responsible for the functions of the adult sensory organ: detection of sound, position and acceleration. The neurons that transmit auditory and balance information to the brain are also born at the otocyst by neurogenesis facilitated by autophagy. Cellular senescence participates in tissue repair, cancer and aging, situations in which cells enter a permanent cell cycle arrest and acquire a highly secretory phenotype that modulates their microenvironment. More recently, senescence has also been proposed to take place during vertebrate development in a limited number of transitory structures and organs; among the later, the endolymphatic duct in the inner ear. Here, we review these cellular processes during the early development of the inner ear, focusing on how the most recently described cellular senescence participates and cooperates with proliferation, apoptosis and autophagy to achieve otic morphogenesis and differentiation.
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Affiliation(s)
- Isabel Varela-Nieto
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain; Centre for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain; Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
| | - Ignacio Palmero
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain
| | - Marta Magariños
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain; Centre for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain; Biology Department, Faculty of Sciences, Autonomous University of Madrid (UAM), Madrid, Spain.
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Magariños M, Contreras J, Aburto MR, Varela-Nieto I. Early development of the vertebrate inner ear. Anat Rec (Hoboken) 2012; 295:1775-90. [PMID: 23044927 DOI: 10.1002/ar.22575] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 12/12/2022]
Abstract
This is a review of the biological processes and the main signaling pathways required to generate the different otic cell types, with particular emphasis on the actions of insulin-like growth factor I. The sensory organs responsible of hearing and balance have a common embryonic origin in the otic placode. Lineages of neural, sensory, and support cells are generated from common otic neuroepithelial progenitors. The sequential generation of the cell types that will form the adult inner ear requires the coordination of cell proliferation with cell differentiation programs, the strict regulation of cell survival, and the metabolic homeostasis of otic precursors. A network of intracellular signals operates to coordinate the transcriptional response to the extracellular input. Understanding the molecular clues that direct otic development is fundamental for the design of novel treatments for the protection and repair of hearing loss and balance disorders.
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Affiliation(s)
- Marta Magariños
- Instituto de Investigaciones Biomédicas, Alberto Sols, CSIC-UAM, Madrid, Spain
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Aburto MR, Magariños M, Leon Y, Varela-Nieto I, Sanchez-Calderon H. AKT signaling mediates IGF-I survival actions on otic neural progenitors. PLoS One 2012; 7:e30790. [PMID: 22292041 PMCID: PMC3264639 DOI: 10.1371/journal.pone.0030790] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 12/29/2011] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Otic neurons and sensory cells derive from common progenitors whose transition into mature cells requires the coordination of cell survival, proliferation and differentiation programmes. Neurotrophic support and survival of post-mitotic otic neurons have been intensively studied, but the bases underlying the regulation of programmed cell death in immature proliferative otic neuroblasts remains poorly understood. The protein kinase AKT acts as a node, playing a critical role in controlling cell survival and cell cycle progression. AKT is activated by trophic factors, including insulin-like growth factor I (IGF-I), through the generation of the lipidic second messenger phosphatidylinositol 3-phosphate by phosphatidylinositol 3-kinase (PI3K). Here we have investigated the role of IGF-dependent activation of the PI3K-AKT pathway in maintenance of otic neuroblasts. METHODOLOGY/PRINCIPAL FINDINGS By using a combination of organotypic cultures of chicken (Gallus gallus) otic vesicles and acoustic-vestibular ganglia, Western blotting, immunohistochemistry and in situ hybridization, we show that IGF-I-activation of AKT protects neural progenitors from programmed cell death. IGF-I maintains otic neuroblasts in an undifferentiated and proliferative state, which is characterised by the upregulation of the forkhead box M1 (FoxM1) transcription factor. By contrast, our results indicate that post-mitotic p27(Kip)-positive neurons become IGF-I independent as they extend their neuronal processes. Neurons gradually reduce their expression of the Igf1r, while they increase that of the neurotrophin receptor, TrkC. CONCLUSIONS/SIGNIFICANCE Proliferative otic neuroblasts are dependent on the activation of the PI3K-AKT pathway by IGF-I for survival during the otic neuronal progenitor phase of early inner ear development.
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Affiliation(s)
- Maria R Aburto
- Instituto de Investigaciones Biomedicas Alberto Sols, CSIC-UAM, Madrid, Spain
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Ceramide 1-phosphate induces neointimal formation via cell proliferation and cell cycle progression upstream of ERK1/2 in vascular smooth muscle cells. Exp Cell Res 2011; 317:2041-51. [DOI: 10.1016/j.yexcr.2011.05.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 01/26/2023]
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Magariños M, Aburto MR, Sánchez-Calderón H, Muñoz-Agudo C, Rapp UR, Varela-Nieto I. RAF kinase activity regulates neuroepithelial cell proliferation and neuronal progenitor cell differentiation during early inner ear development. PLoS One 2010; 5:e14435. [PMID: 21203386 PMCID: PMC3010996 DOI: 10.1371/journal.pone.0014435] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 11/24/2010] [Indexed: 12/21/2022] Open
Abstract
Background Early inner ear development requires the strict regulation of cell proliferation, survival, migration and differentiation, coordinated by the concerted action of extrinsic and intrinsic factors. Deregulation of these processes is associated with embryonic malformations and deafness. We have shown that insulin-like growth factor I (IGF-I) plays a key role in embryonic and postnatal otic development by triggering the activation of intracellular lipid and protein kinases. RAF kinases are serine/threonine kinases that regulate the highly conserved RAS-RAF-MEK-ERK signaling cascade involved in transducing the signals from extracellular growth factors to the nucleus. However, the regulation of RAF kinase activity by growth factors during development is complex and still not fully understood. Methodology/Principal Findings By using a combination of qRT-PCR, Western blotting, immunohistochemistry and in situ hybridization, we show that C-RAF and B-RAF are expressed during the early development of the chicken inner ear in specific spatiotemporal patterns. Moreover, later in development B-RAF expression is associated to hair cells in the sensory patches. Experiments in ex vivo cultures of otic vesicle explants demonstrate that the influence of IGF-I on proliferation but not survival depends on RAF kinase activating the MEK-ERK phosphorylation cascade. With the specific RAF inhibitor Sorafenib, we show that blocking RAF activity in organotypic cultures increases apoptosis and diminishes the rate of cell proliferation in the otic epithelia, as well as severely impairing neurogenesis of the acoustic-vestibular ganglion (AVG) and neuron maturation. Conclusions/Significance We conclude that RAF kinase activity is essential to establish the balance between cell proliferation and death in neuroepithelial otic precursors, and for otic neuron differentiation and axonal growth at the AVG.
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Affiliation(s)
- Marta Magariños
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Madrid, Spain.
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Bornancin F. Ceramide kinase: the first decade. Cell Signal 2010; 23:999-1008. [PMID: 21111813 DOI: 10.1016/j.cellsig.2010.11.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 11/16/2010] [Accepted: 11/16/2010] [Indexed: 11/20/2022]
Abstract
It has been some 20 years since the initial discovery of ceramide 1-phosphate (C1P) and nearly a decade since ceramide kinase (CERK) was cloned. Many studies have shown that C1P is important for membrane biology and for the regulation of membrane-bound proteins, and the CERK enzyme has appeared to be tightly regulated in order to control both ceramide levels and production of C1P. Furthermore, C1P made by CERK has emerged as a genuine signalling entity. However, it represents only part of the C1P pool that is available in the cell, therefore suggesting that alternative unknown C1P-producing mechanisms may also play a role. Recent technological developments for measuring complex sphingolipids in biological samples, together with the availability of Cerk-deficient animals as well as potent CERK inhibitors, have now provided new grounds for investigating C1P biology further. Here, we will review the current understanding of CERK and C1P in terms of biochemistry and functional implications, with particular attention to C1P produced by CERK.
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Affiliation(s)
- Frédéric Bornancin
- Novartis Institutes for BioMedical Research, CH-4056 Basle, Switzerland.
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The role of PSA-NCAM in adult neurogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 663:127-36. [PMID: 20017019 DOI: 10.1007/978-1-4419-1170-4_8] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Gascon E, Vutskits L, Kiss JZ. Polysialic acid–neural cell adhesion molecule in brain plasticity: From synapses to integration of new neurons. ACTA ACUST UNITED AC 2007; 56:101-18. [PMID: 17658613 DOI: 10.1016/j.brainresrev.2007.05.014] [Citation(s) in RCA: 192] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 04/02/2007] [Accepted: 05/24/2007] [Indexed: 11/15/2022]
Abstract
Isoforms of the neuronal cell adhesion molecule (NCAM) carrying the linear homopolymer of alpha 2,8-linked sialic acid (polysialic acid, PSA) have emerged as particularly attractive candidates for promoting plasticity in the nervous system. The large negatively charged PSA chain of NCAM is postulated to be a spacer that reduces adhesion forces between cells allowing dynamic changes in membrane contacts. Accumulating evidence also suggests that PSA-NCAM-mediated interactions lead to activation of intracellular signaling cascades that are fundamental to the biological functions of the molecule. An important role of PSA-NCAM appears to be during development, when its expression level is high and where it contributes to the regulation of cell shape, growth or migration. However, PSA-NCAM does persist in adult brain structures such as the hippocampus that display a high degree of plasticity where it is involved in activity-induced synaptic plasticity. Recent advances in the field of PSA-NCAM research have not only consolidated the importance of this molecule in plasticity processes but also suggest a role for PSA-NCAM in the regulation of higher cognitive functions and psychiatric disorders. In this review, we discuss the role and mode of actions of PSA-NCAM in structural plasticity as well as its potential link to cognitive processes.
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Affiliation(s)
- Eduardo Gascon
- Department of Neuroscience, University of Geneva Medical School, 1, Rue Michel Servet, CH-1211, Geneva, Switzerland
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Abstract
Neurotrophin stimulation of tropomyosin-related kinase (Trk) and p75 receptors influences cellular processes such as proliferation, growth, differentiation, and other cell-specific functions, as well as regeneration. In contrast to Trk receptors, which have a well-defined trophic role, p75 has activities ranging from trophism to apoptosis. Continued neurotrophin stimulation of differentiating neurons transforms the initially trophic character of p75 signaling into negative growth control and overstimulation leads to apoptosis. This function shift reflects the signaling effects of ceramide that is generated upon stimulation of p75. The use of ceramide signaling by p75 may provide a key to understanding the cell-biological role of p75. The review presents arguments that the control of cell shape formation and cell selection can serve as an organizing principle of p75 signaling. Concurrent stimulation by neurotrophins of p75 and Trk receptors constitutes a dual growth control with antagonistic and synergistic elements aimed at optimal morphological and functional integration of cells and cell populations into their context.
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Affiliation(s)
- A Blöchl
- Biochemie II, Fakultät Chemie und Biochemie, Ruhr-Universität Bochum, Bochum, Germany.
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Gascon E, Vutskits L, Jenny B, Durbec P, Kiss JZ. PSA-NCAM in postnatally generated immature neurons of the olfactory bulb: a crucial role in regulating p75 expression and cell survival. Development 2007; 134:1181-90. [PMID: 17301083 DOI: 10.1242/dev.02808] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the mammalian brain, ongoing neurogenesis via the rostral migratory stream (RMS) maintains neuronal replacement in the olfactory bulb throughout life. Mechanisms that regulate the final number of new neurons in this system include proliferation, migration and apoptosis. Here we show that the polysialylated isoforms of the neural cell adhesion molecule (PSA-NCAM) act as a pro-survival molecule in immature newborn neurons. Confocal microscopic analysis revealed a threefold increase in TUNEL-positive cells in the subventricular zone (SVZ) and the RMS of transgenic animals lacking the gene encoding NCAM (NCAM(-/-)), as compared with wild types. The enhanced apoptotic cell death occurred specifically in the population of mCD24-positive newborn neurons, but not in GFAP-positive astrocytes. Using in vitro cultures of purified SVZ-derived neurons, we demonstrate that the loss or inactivation of PSA on NCAM, as well as the deletion of NCAM, lead to reduced survival in response to neurotrophins including BDNF and NGF. These changes in cell survival are accompanied by an upregulation of p75 neurotrophin receptor expression in vitro as well as in vivo. Furthermore, the negative effects of PSA-NCAM inactivation on cell survival could be prevented by the pharmacological blockade of the p75 receptor-signaling pathway. We propose that PSA-NCAM may promote survival by controlling the expression of the p75 receptor in developing neurons.
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Affiliation(s)
- Eduardo Gascon
- Department of Neuroscience, University of Geneva Medical School, CH-1211 Geneva, Switzerland
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Marcu AC, Chalfant CE. Ceramide-1-phosphate, a new bioactive sphingolipid in regulating cell signaling. ACTA ACUST UNITED AC 2007. [DOI: 10.2217/17460875.2.1.75] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kurmasheva RT, Houghton PJ. IGF-I mediated survival pathways in normal and malignant cells. Biochim Biophys Acta Rev Cancer 2006; 1766:1-22. [PMID: 16844299 DOI: 10.1016/j.bbcan.2006.05.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 05/23/2006] [Accepted: 05/25/2006] [Indexed: 02/07/2023]
Abstract
The type-I and -II insulin-like growth factors (IGF-I, II) are now established as survival- or proliferation-factors in many in vitro systems. Of note IGFs provide trophic support for multiple cell types or organ cultures explanted from various species, and delay the onset of programmed cell death (apoptosis) through the mitochondrial (intrinsic pathway) or by antagonizing activation of cytotoxic cytokine signaling (extrinsic pathway). In some instances, IGFs protect against other forms of death such as necrosis or autophagy. The effect of IGFs on cell survival appears to be context specific, being determined both by the cell origin (tissue specific) and the cellular stress that induces loss of cellular viability. In many human cancers, there is a strong association with dysregulated IGF signaling, and this association has been extensively reviewed recently. IGF-regulation is also disrupted in childhood cancers as a consequence of chromosomal translocations. IGFs are implicated also in acute renal failure, traumatic injury to brain tissue, and cardiac disease. This article focuses on the role of IGFs and their cellular signaling pathways that provide survival signals in stressed cells.
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Affiliation(s)
- Raushan T Kurmasheva
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105-2794, USA
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Gómez-Muñoz A. Ceramide 1-phosphate/ceramide, a switch between life and death. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:2049-56. [PMID: 16808893 DOI: 10.1016/j.bbamem.2006.05.011] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Revised: 05/04/2006] [Accepted: 05/11/2006] [Indexed: 12/26/2022]
Abstract
Ceramide is a well-characterized sphingolipid metabolite and second messenger that participates in numerous biological processes. In addition to serving as a precursor to complex sphingolipids, ceramide is a potent signaling molecule capable of regulating vital cellular functions. Perhaps its major role in signal transduction is to induce cell cycle arrest, and promote apoptosis. In contrast, little is known about the metabolic or signaling pathways that are regulated by the phosphorylated form of ceramide. It was first demonstrated that ceramide-1-phosphate (C1P) had mitogenic properties, and more recently it has been described as potent inhibitor of apoptosis and inducer of cell survival. C1P and ceramide are antagonistic molecules that can be interconverted in cells by kinase and phosphatase activities. An appropriate balance between the levels of these two metabolites seems to be crucial for cell and tissue homeostasis. Switching this balance towards accumulation of one or the other may result in metabolic dysfunction, or disease. Therefore, the activity of the enzymes that are involved in C1P and ceramide metabolism must be efficiently coordinated to ensure normal cell functioning.
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Affiliation(s)
- Antonio Gómez-Muñoz
- Department of Biochemistry and Molecular Biology, University of the Basque Country, P.O. Box 644, 48080-Bilbao, Spain.
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Nordell VL, Lewis DK, Bake S, Sohrabji F. The neurotrophin receptor p75NTR mediates early anti-inflammatory effects of estrogen in the forebrain of young adult rats. BMC Neurosci 2005; 6:58. [PMID: 16156894 PMCID: PMC1239918 DOI: 10.1186/1471-2202-6-58] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 09/12/2005] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Estrogen suppresses microglial activation and extravasation of circulating monocytes in young animals, supporting an anti-inflammatory role for this hormone. However, the mechanisms underlying estrogen's anti-inflammatory effects, especially in vivo, are not well understood. The present study tests the hypothesis that anti-inflammatory effects of estrogen are mediated by the pan-neurotrophin receptor p75NTR. Previously, we reported that estrogen attenuated local increases of interleukin(IL)-1beta in the NMDA-lesioned olfactory bulb, while further increasing NGF expression. RESULTS The present studies show that this lesion enhances expression of the neurotrophin receptor p75NTR at the lesion site, and p75NTR expression is further enhanced by estrogen treatment to lesioned animals. Specifically, estrogen stimulates p75NTR expression in cells of microvessels adjacent to the lesion site. To determine the role of this receptor in mediating estrogen's anti-inflammatory effects, a p75NTR neutralizing antibody was administered at the same time the lesion was created (by stereotaxic injections of NMDA) and specific markers of the inflammatory cascade were measured. Olfactory bulb injections of NMDA+vehicle (preimmune serum) increased IL-1beta and activated the signaling molecule c-jun terminal kinase (JNK)-2 at 6 h. At 24 h, the lesion significantly increased matrix metalloproteinase (MMP)-9 and prostaglandin (PG)E2, a COX-2 mediated metabolite of arachadonic acid. All of these markers were significantly attenuated by estrogen in a time-dependent manner. However, estrogen's effects on all these markers were abolished in animals that received anti-p75NTR. CONCLUSION These data support the hypothesis that estrogen's anti-inflammatory effects may be, in part, mediated by this neurotrophin receptor. In view of the novel estrogen-dependent expression of p75NTR in cells associated with microvessels, these data also suggest that the blood brain barrier is a critical locus of estrogen's neuro-immune effects.
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Affiliation(s)
- Vanessa L Nordell
- Department of Human Anatomy and Medical Neurobiology, Texas A&M University System Health Science Center College of Medicine, College Station, TX, 77843 USA
| | - Danielle K Lewis
- Department of Human Anatomy and Medical Neurobiology, Texas A&M University System Health Science Center College of Medicine, College Station, TX, 77843 USA
| | - Shameena Bake
- Department of Human Anatomy and Medical Neurobiology, Texas A&M University System Health Science Center College of Medicine, College Station, TX, 77843 USA
| | - Farida Sohrabji
- Department of Human Anatomy and Medical Neurobiology, Texas A&M University System Health Science Center College of Medicine, College Station, TX, 77843 USA
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Gómez-Muñoz A, Kong JY, Parhar K, Wang SW, Gangoiti P, González M, Eivemark S, Salh B, Duronio V, Steinbrecher UP. Ceramide-1-phosphate promotes cell survival through activation of the phosphatidylinositol 3-kinase/protein kinase B pathway. FEBS Lett 2005; 579:3744-50. [PMID: 15978590 DOI: 10.1016/j.febslet.2005.05.067] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 05/13/2005] [Accepted: 05/31/2005] [Indexed: 01/29/2023]
Abstract
In this report, we show for the first time that ceramide-1-phosphate (C1P) stimulates the phosphatidylinositol 3-kinase (PI3-K)/protein kinase B (PKB) pathway, which is a major mechanism whereby growth factors promote cell survival. Also, C1P induced IkappaB phosphorylation, and enhanced the DNA binding activity of the transcription factor NF-kappaB. Apoptotic macrophages showed a marked reduction of Bcl-X(L) levels, and this was prevented by C1P. These findings suggest that C1P blocks apoptosis, at least in part, by stimulating the PI3-K/PKB/NF-kappaB pathway and maintaining the production of antiapoptotic Bcl-X(L). Based on these and our previous observations, we propose a working model for C1P in which inhibition of acid sphingomyelinase and the subsequent decrease in ceramide levels would allow cell signaling through stimulation of the PI3-K/PKB pathway to promote cell survival.
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Affiliation(s)
- Antonio Gómez-Muñoz
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain.
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Gascon E, Vutskits L, Zhang H, Barral-Moran MJ, Kiss PJ, Mas C, Kiss JZ. Sequential activation of p75 and TrkB is involved in dendritic development of subventricular zone-derived neuronal progenitors in vitro. Eur J Neurosci 2005; 21:69-80. [PMID: 15654844 DOI: 10.1111/j.1460-9568.2004.03849.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Dendritic arbor development of subventricular zone-derived interneurons is a critical step in their integration into functional circuits of the postnatal olfactory bulb. However, the mechanism and molecular control of this process remain unknown. In this study, we have developed a culture model where dendritic development of purified subventricular zone cells proceeds under serum-free conditions in the absence of added growth factors and non-neural cells. We demonstrate that the large majority of these cells in culture express GABA and elaborate dendritic arbors with spine-like protrusions but they do not possess axons. These neurons expressed receptors for neurotrophins including p75, TrkB and TrkC but not TrkA. Application of exogenous neurotrophins, including brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and nerve growth factor (NGF), to cultures stimulated dendritic growth and led to more complex dendritic arbors during the initial 3 days in culture. Our results suggest that these effects are independent of Trk receptors and mediated by the p75/ceramide signaling pathway. We also show that brain-derived neurotrophic factor is the only neurotrophin that is able to influence late-phase dendritic development via TrkB receptor activation. These results suggest that dendritic arbor development of subventricular zone-derived cells may be regulated by neurotrophins through the activation of p75 and the TrkB receptor signaling pathways in a sequentially defined temporal pattern.
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Affiliation(s)
- E Gascon
- Department of Neuroscience, University of Geneva Medical School, 1 Rue Michel Servet, CH-1211, Geneva, Switzerland
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21
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Lang PA, Kempe DS, Tanneur V, Eisele K, Klarl BA, Myssina S, Jendrossek V, Ishii S, Shimizu T, Waidmann M, Hessler G, Huber SM, Lang F, Wieder T. Stimulation of erythrocyte ceramide formation by platelet-activating factor. J Cell Sci 2005; 118:1233-43. [PMID: 15741229 DOI: 10.1242/jcs.01730] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Osmotic erythrocyte shrinkage leads to activation of cation channels with subsequent Ca2+ entry and stimulates a sphingomyelinase with subsequent formation of ceramide. Ca2+ and ceramide then activate a scramblase leading to breakdown of phosphatidylserine asymmetry of the cell membrane. The mediators accounting for activation of erythrocyte sphingomyelinase and phosphatidylserine exposure remained elusive. The study demonstrates that platelet-activating factor (PAF) is released from erythrocytes upon hyperosmotic cell shrinkage. The experiments further disclose the presence of PAF receptors in erythrocytes and show that PAF stimulates the breakdown of sphingomyelin and the release of ceramide from erythrocytes at isotonic conditions. PAF further triggers cell shrinkage (decrease of forward scatter) and phosphatidylserine exposure (annexin binding) of erythrocytes. The stimulation of annexin-binding is blunted by a genetic knockout of PAF receptors, by the PAF receptor antagonist ABT491 or by inhibition of sphingomyelinase with urea. In conclusion, PAF activates an erythrocyte sphingomyelinase and the then formed ceramide leads to the activation of scramblase with subsequent phosphatidylserine exposure.
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Affiliation(s)
- Philipp A Lang
- Department of Physiology, University of Tübingen, Germany
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22
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Colombaioni L, Garcia-Gil M. Sphingolipid metabolites in neural signalling and function. ACTA ACUST UNITED AC 2004; 46:328-55. [PMID: 15571774 DOI: 10.1016/j.brainresrev.2004.07.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2004] [Indexed: 11/20/2022]
Abstract
Sphingolipid metabolites, such as ceramide, sphingosine, sphingosine-1-phosphate (S1P) and complex sphingolipids (gangliosides), are recognized as molecules capable of regulating a variety of cellular processes. The role of sphingolipid metabolites has been studied mainly in non-neuronal tissues. These studies have underscored their importance as signals transducers, involved in control of proliferation, survival, differentiation and apoptosis. In this review, we will focus on studies performed over the last years in the nervous system, discussing the recent developments and the current perspectives in sphingolipid metabolism and functions.
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23
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Varela-Nieto I, Morales-Garcia JA, Vigil P, Diaz-Casares A, Gorospe I, Sánchez-Galiano S, Cañon S, Camarero G, Contreras J, Cediel R, Leon Y. Trophic effects of insulin-like growth factor-I (IGF-I) in the inner ear. Hear Res 2004; 196:19-25. [PMID: 15464297 DOI: 10.1016/j.heares.2003.12.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Accepted: 12/23/2003] [Indexed: 11/27/2022]
Abstract
Insulin-like growth factors (IGFs) have a pivotal role during nervous system development and in its functional maintenance. IGF-I and its high affinity receptor (IGF1R) are expressed in the developing inner ear and in the postnatal cochlear and vestibular ganglia. We recently showed that trophic support by IGF-I is essential for the early neurogenesis of the chick cochleovestibular ganglion (CVG). In the chicken embryo otic vesicle, IGF-I regulates developmental death dynamics by regulating the activity and/or levels of key intracellular molecules, including lipid and protein kinases such as ceramide kinase, Akt and Jun N-terminal kinase (JNK). Mice lacking IGF-I lose many auditory neurons and present increased auditory thresholds at early postnatal ages. Neuronal loss associated to IGF-I deficiency is caused by apoptosis of the auditory neurons, which presented abnormally increased levels of activated caspase-3. It is worth noting that in man, homozygous deletion of the IGF-1 gene causes sensory-neural deafness. IGF-I is thus necessary for normal development and maintenance of the inner ear. The trophic actions of IGF-I in the inner ear suggest that this factor may have therapeutic potential for the treatment of hearing loss.
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Affiliation(s)
- Isabel Varela-Nieto
- Instituto de Investigaciones Biomedicas Alberto Sols, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, "Alberto Sols", Arturo Duperier 4, 28029 Madrid, Spain.
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24
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Abstract
Ceramide-1-phosphate (CER-1-P) is emerging as a novel bioactive sphingolipid. It is formed by phosphorylation of ceramide catalyzed by ceramide kinase, and has been implicated in different cellular processes. Cer-1-P is mitogenic for fibroblasts, blocks apoptosis in macrophages, controls phagocytosis in neutrophils, and mediates inflammatory responses. Only recently have we started to uncover the signaling pathways that cytosolic phospholipase A2 and acid sphingomyelinase are direct intracellular targets of Cer-1-P, and that it may also induce phosphorylation of extracellular signal-regulated kinase-2 and calcium mobilization. These actions of Cer-1-P seem to be cell type-specific.
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Affiliation(s)
- Antonio Gómez-Muñoz
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain.
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25
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Alsina B, Abelló G, Ulloa E, Henrique D, Pujades C, Giraldez F. FGF signaling is required for determination of otic neuroblasts in the chick embryo. Dev Biol 2004; 267:119-34. [PMID: 14975721 DOI: 10.1016/j.ydbio.2003.11.012] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Revised: 10/01/2003] [Accepted: 11/10/2003] [Indexed: 10/26/2022]
Abstract
The interplay between intrinsic and extrinsic factors is essential for the transit into different cell states during development. We have analyzed the expression and function of FGF10 and FGF-signaling during the early stages of the development of otic neurons. FGF10 is expressed in a highly restricted domain overlapping the presumptive neurogenic region of the chick otic placode. A detailed study of the expression pattern of FGF10, proneural, and neurogenic genes revealed the following temporal sequence for the onset of gene expression: FGF10>Ngn1/Delta1/Hes5>NeuroD/NeuroM. FGF10 and FGF receptor inhibition cause opposed effects on cell determination and cell proliferation. Ectopic expression of FGF10 in vivo promotes an increase in NeuroD and NeuroM expression. BrdU incorporation experiments showed that the increase in NeuroD-expressing cells is not due to an increase in cell proliferation. Inhibition of FGF receptor signaling in otic explants causes a severe reduction in Neurogenin1, NeuroD, Delta1, and Hes5 expression with no change in non-neural genes like Lmx1. However, it does not interfere with NeuroD expression within the CVG or with neuroblast delamination. The loss of proneural gene expression caused by FGF inhibition is not caused by decreased cell proliferation or by increased cell death. We suggest that FGF signaling in the otic epithelium is required for neuronal precursors to withdraw from cell division and irreversibly commit to neuronal fate.
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Affiliation(s)
- Berta Alsina
- Biologia del Desenvolupament, Departament de Ciéncies Experimentals i de la Salut (DCEXS), Universitat Pompeu Fabra, 08003, Barcelona, Spain.
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26
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Affiliation(s)
- Ulla Pirvola
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
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27
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Tuson M, Marfany G, Gonzàlez-Duarte R. Mutation of CERKL, a novel human ceramide kinase gene, causes autosomal recessive retinitis pigmentosa (RP26). Am J Hum Genet 2004; 74:128-38. [PMID: 14681825 PMCID: PMC1181900 DOI: 10.1086/381055] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Accepted: 10/27/2003] [Indexed: 11/03/2022] Open
Abstract
Retinitis pigmentosa (RP), the main cause of adult blindness, is a genetically heterogeneous disorder characterized by progressive loss of photoreceptors through apoptosis. Up to now, 39 genes and loci have been implicated in nonsyndromic RP, yet the genetic bases of >50% of the cases, particularly of the recessive forms, remain unknown. Previous linkage analysis in a Spanish consanguineous family allowed us to define a novel autosomal recessive RP (arRP) locus, RP26, within an 11-cM interval (17.4 Mb) on 2q31.2-q32.3. In the present study, we further refine the RP26 locus down to 2.5 Mb, by microsatellite and single-nucleotide polymorphism (SNP) homozygosity mapping. After unsuccessful mutational analysis of the nine genes initially reported in this region, a detailed gene search based on expressed-sequence-tag data was undertaken. We finally identified a novel gene encoding a ceramide kinase (CERKL), which encompassed 13 exons. All of the patients from the RP26 family bear a homozygous mutation in exon 5, which generates a premature termination codon. The same mutation was also characterized in another, unrelated, Spanish pedigree with arRP. Human CERKL is expressed in the retina, among other adult and fetal tissues. A more detailed analysis by in situ hybridization on adult murine retina sections shows expression of Cerkl in the ganglion cell layer. Ceramide kinases convert the sphingolipid metabolite ceramide into ceramide-1-phosphate, both key mediators of cellular apoptosis and survival. Ceramide metabolism plays an essential role in the viability of neuronal cells, the membranes of which are particularly rich in sphingolipids. Therefore, CERKL deficiency could shift the relative levels of the signaling sphingolipid metabolites and increase sensitivity of photoreceptor and other retinal cells to apoptotic stimuli. This is the first genetic report suggesting a direct link between retinal neurodegeneration in RP and sphingolipid-mediated apoptosis.
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Affiliation(s)
- Miquel Tuson
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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28
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Gómez-Muñoz A, Kong JY, Salh B, Steinbrecher UP. Ceramide-1-phosphate blocks apoptosis through inhibition of acid sphingomyelinase in macrophages. J Lipid Res 2003; 45:99-105. [PMID: 14523050 DOI: 10.1194/jlr.m300158-jlr200] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
It was reported previously that ceramide-1-phosphate (Cer-1-P) is mitogenic for fibroblasts (Gómez-Muñoz, A., P. A. Duffy, A. Martin, L. O'Brien, H-S. Byun, R. Bittman, and D. N. Brindley. 1995. Mol. Pharmacol. 47: 883-889; Gómez-Muñoz, A., L. M. Frago, L. Alvarez, and I. Varela-Nieto. 1997. Biochem. J. 325: 435-440). We now show that Cer-1-P prevents cell death in bone-marrow-derived macrophages (BMDMs) after withdrawal of macrophage colony-stimulating factor (M-CSF). Removal of M-CSF is known to induce apoptosis in these cells. Cer-1-P blocked activation of the caspase-9/caspase-3 pathway and prevented DNA fragmentation, indicating that the enhancement of cell survival was due to inhibition of apoptosis. M-CSF deprivation resulted in activation of acid sphingomyelinase (A-SMase), increased ceramide levels, and a decrease in intracellular Cer-1-P. Exogenously added Cer-1-P inhibited A-SMase in intact BMDMs at concentrations that also prevented apoptosis. Cer-1-P also inhibited A-SMase in cell homogenates, suggesting a possible direct physical interaction of Cer-1-P with the enzyme. In conclusion, these data demonstrate that Cer-1-P blocks apoptosis in BMDMs through inhibition of A-SMase, thereby reducing ceramide generation. This adds a new dimension to the understanding of the metabolic interrelationship of ceramides and Cer-1-P, and shows how altering the balance of intracellular levels of these mediators can affect cell survival.
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Affiliation(s)
- Antonio Gómez-Muñoz
- Department of Biochemistry and Molecular Biology, University of the Basque Country, PO Box 644, 48080 Bilbao, Spain.
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29
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Camarero G, Leon Y, Gorospe I, De Pablo F, Alsina B, Giraldez F, Varela-Nieto I. Insulin-like growth factor 1 is required for survival of transit-amplifying neuroblasts and differentiation of otic neurons. Dev Biol 2003; 262:242-53. [PMID: 14550788 DOI: 10.1016/s0012-1606(03)00387-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neurons that connect mechanosensory hair cell receptors to the central nervous system derive from the otic vesicle from where otic neuroblasts delaminate and form the cochleovestibular ganglion (CVG). Local signals interact to promote this process, which is autonomous and intrinsic to the otic vesicle. We have studied the expression and activity of insulin-like growth factor-1 (IGF-1) during the formation of the chick CVG, focusing attention on its role in neurogenesis. IGF-1 and its receptor (IGFR) were detected at the mRNA and protein levels in the otic epithelium and the CVG. The function of IGF-1 was explored in explants of otic vesicle by assessing the formation of the CVG in the presence of anti-IGF-1 antibodies or the receptor competitive antagonist JB1. Interference with IGF-1 activity inhibited CVG formation in growth factor-free media, revealing that endogenous IGF-1 activity is essential for ganglion generation. Analysis of cell proliferation cell death, and expression of the early neuronal antigens Tuj-1, Islet-1/2, and G4 indicated that IGF-1 was required for survival, proliferation, and differentiation of an actively expanding population of otic neuroblasts. IGF-1 blockade, however, did not affect NeuroD within the otic epithelium. Experiments carried out on isolated CVG showed that exogenous IGF-1 induced cell proliferation, neurite outgrowth, and G4 expression. These effects of IGF-1 were blocked by JB1. These findings suggest that IGF-1 is essential for neurogenesis by allowing the expansion of a transit-amplifying neuroblast population and its differentiation into postmitotic neurons. IGF-1 is one of the signals underlying autonomous development of the otic vesicle.
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Affiliation(s)
- G Camarero
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Cientificas (CSIC)-Universidad Autónoma de Madrid (UAM), Arturo Duperier 4, E-28029, Madrid, Spain
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30
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Frago LM, Cañón S, de la Rosa EJ, León Y, Varela-Nieto I. Programmed cell death in the developing inner ear is balanced by nerve growth factor and insulin-like growth factor I. J Cell Sci 2003; 116:475-86. [PMID: 12508109 DOI: 10.1242/jcs.00223] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nerve growth factor induces cell death in organotypic cultures of otic vesicle explants. This cell death has a restricted pattern that reproduces the in vivo pattern of apoptosis occurring during inner ear development. In this study, we show that binding of nerve growth factor to its low affinity p75 neurotrophin receptor is essential to achieve the apoptotic response. Blockage of binding to p75 receptor neutralized nerve-growth-factor-induced cell death, as measured by immunoassays detecting the presence of cytosolic oligonucleosomes and by TUNEL assay to visualize DNA fragmentation. Nerve growth factor also induced a number of cell-death-related intracellular events including ceramide generation, caspase activation and poly-(ADP ribose) polymerase cleavage. Again, p75 receptor blockade completely abolished all of these effects. Concerning the intracellular pathway, ceramide increase depended on initiator caspases, whereas its actions depended on both initiator and effector caspases, as shown by using site-specific caspase inhibitors. Conversely, insulin-like growth factor I, which promotes cell growth and survival in the inner ear, abolished apoptosis induced by nerve growth factor. Insulin-like growth factor cytoprotective actions were accomplished, at least in part, by decreasing endogenous ceramide levels and activating Akt. Taken together, these results strongly suggest that regulation of nerve-growth-factor-induced apoptosis in the otocysts occurs via p75 receptor binding and is strictly controlled by the interaction with survival signalling pathways.
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Affiliation(s)
- Laura M Frago
- Instituto de Investigaciones Biomédicas "Alberto Sols", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain
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31
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Pertseva MN, Shpakov AO, Plesneva SA, Kuznetsova LA. A novel view on the mechanisms of action of insulin and other insulin superfamily peptides: involvement of adenylyl cyclase signaling system. Comp Biochem Physiol B Biochem Mol Biol 2003; 134:11-36. [PMID: 12524030 DOI: 10.1016/s1096-4959(02)00160-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A new signaling mechanism common to mammalian insulin, insulin-like growth factor I, relaxin and mollusc insulin-like peptide, and involving receptor-tyrosine kinase==>G(i) protein (betagamma)==>phosphatidylinositol-3-kinase==>protein kinase Czeta==>adenylyl cyclase==>protein kinase A was discovered in the muscles and some other tissues of vertebrates and invertebrates. The authors' data were used to reconsider the problem of participation of the adenylyl cyclase-cAMP system in the regulatory effects of insulin superfamily peptides. A hypothesis has been put forward according to which the adenylyl cyclase signaling mechanism producing cAMP has a triple co-ordinating role in the regulatory action of insulin superfamily peptides on the main cell processes, inducing the mitogenic and antiapoptotic effects and inhibitory influence on some metabolic effects of the peptides. It is suggested that cAMP is a key regulator responsible for choosing the transduction pathway by concerted launching of one (proliferative) program and switching off (suppression) of two others, which lead to cell death and to the predomination of anabolic processes in a cell. The original data obtained give grounds to conclude that the adenylyl cyclase signaling system is a mechanism of signal transduction not only of hormones with serpentine receptors, but also of those with receptors of the tyrosine kinase type (insulin superfamily peptides and some growth factors).
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Affiliation(s)
- M N Pertseva
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez av. 44, 194223 St. Petersburg, Russia.
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32
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Alsina B, Giraldez F, Varela-Nieto I. Growth Factors and Early Development of Otic Neurons: Interactions between Intrinsic and Extrinsic Signals. Curr Top Dev Biol 2003; 57:177-206. [PMID: 14674481 DOI: 10.1016/s0070-2153(03)57006-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Berta Alsina
- DCEXS-Universitat Pomepu Fabra, Dr Aiguader 80, 08003 Barcelona, Spain
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33
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Salehi AH, Xanthoudakis S, Barker PA. NRAGE, a p75 neurotrophin receptor-interacting protein, induces caspase activation and cell death through a JNK-dependent mitochondrial pathway. J Biol Chem 2002; 277:48043-50. [PMID: 12376548 DOI: 10.1074/jbc.m205324200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The p75 neurotrophin receptor (p75NTR) mediates signaling events leading to activation of the JNK pathway and cell death in a variety of cell types. We recently identified NRAGE, a protein that directly interacts with the p75NTR cytosolic region and facilitates p75NTR-mediated cell death. For the present study, we developed an inducible recombinant NRAGE adenovirus to dissect the mechanism of NRAGE-mediated apoptosis. Induced NRAGE expression resulted in robust activation of the JNK pathway that was not inhibited by the pharmacological mixed lineage kinase (MLK) inhibitor CEP1347. NRAGE induced cytosolic accumulation of cytochrome c, activation of Caspases-3, -9 and -7, and caspase-dependent cell death. Blocking JNK and c-Jun action by overexpression of the JNK-binding domain of JIP1 or dominant-negative c-Jun ablated NRAGE-mediated caspase activation and NRAGE-induced cell death. These findings identify NRAGE as a p75NTR interactor capable of inducing caspase activation and cell death through a JNK-dependent mitochondrial apoptotic pathway.
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Affiliation(s)
- Amir H Salehi
- Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, 3801 University Avenue, Montreal, Quebec H3A 2B4, Canada
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34
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Camarero G, Villar MA, Contreras J, Fernández-Moreno C, Pichel JG, Avendaño C, Varela-Nieto I. Cochlear abnormalities in insulin-like growth factor-1 mouse mutants. Hear Res 2002; 170:2-11. [PMID: 12208536 DOI: 10.1016/s0378-5955(02)00447-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) modulates inner ear cell proliferation, differentiation and survival in culture. Its function in human hearing was first evidenced by a report of a boy with a homozygous deletion of the Igf-1 gene, who showed severe sensorineural deafness [Woods et al., New Engl. J. Med. 335 (1996) 1363-1367]. To better understand the in vivo role of IGF-1 during inner ear differentiation and maturation, we studied the cochleae of Igf-1 gene knockout mice by performing morphometric stereological analyses, immunohistochemistry and electron microscopy on postnatal days 5 (P5), P8 and P20. At P20, but not at P5, the volumes of the cochlea and cochlear ganglion were significantly reduced in mutant mice, although the reduction was less severe than whole body dwarfism. A significant decrease in the number and average size of auditory neurons was also evident at P20. IGF-1-deficient cochlear neurons showed increased apoptosis, along with altered expression of neurofilament 200 kDa and vimentin. The eighth nerve, the cochlear ganglion and the fibers innervating the sensory cells of the organ of Corti of the P20 mouse mutants presented increased expression of vimentin, whereas the expression of neurofilament was decreased. In addition, the myelin sheath was severely affected in ganglion neurons. In conclusion, IGF-1 deficit in mice severely affects postnatal survival, differentiation and maturation of the cochlear ganglion cells.
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Affiliation(s)
- Guadalupe Camarero
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Arturo Duperier 4, 28029, Madrid, Spain
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35
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Rubio E, Valenciano AI, Segundo C, Sánchez N, de Pablo F, de la Rosa EJ. Programmed cell death in the neurulating embryo is prevented by the chaperone heat shock cognate 70. Eur J Neurosci 2002; 15:1646-54. [PMID: 12059972 DOI: 10.1046/j.1460-9568.2002.01998.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuronal cell death is a genuine developmental process, with precise regulation and defined roles. In striking contrast, characterization of cell death that occurs at early stages of neural development is very limited. We previously showed that embryonic proinsulin increases the level of the chaperone heat shock cognate 70 (Hsc70) and reduces the incidence of apoptosis in the neurulating chick embryo [de la Rosa, et al. (1998), Proc. Natl. Acad. Sci. USA, 95, 9950]. We now demonstrate that Hsc70 is directly involved in cell survival during neurulation, as specific downregulation of endogenous Hsc70 by antisense oligodeoxynucleotide interference provoked an increase in apoptosis both in vitro and in ovo. In parallel, activation of caspase-3 was increased after hsc70 antisense oligodeoxynucleotide treatment. Dead cells were located mostly in the developing nervous system, distributed in areas where the incidence of cell death was high. These areas coincided both in vivo and under different death-inducing conditions, including antisense interference and growth factor deprivation. Hsc70 immunostaining was strong in at least some areas of high cell death. Apoptotic cells within these areas presented undetectable Hsc70 levels, however, suggesting that this protein acts as an intrinsic protector of neuroepithelial and neural precursor cells.
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Affiliation(s)
- Eva Rubio
- Group of Growth Factors in Vertebrate Development, Department of Cell and Developmental Biology, Centro de Investigaciones Biológicas, CSIC, Velázquez 144, E-28006 Madrid, Spain
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36
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Colombaioni L, Frago LM, Varela-Nieto I, Pesi R, Garcia-Gil M. Serum deprivation increases ceramide levels and induces apoptosis in undifferentiated HN9.10e cells. Neurochem Int 2002; 40:327-36. [PMID: 11792463 DOI: 10.1016/s0197-0186(01)00090-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sphingolipid metabolites have been involved in the regulation of proliferation, differentiation and apoptosis. While cellular mechanisms of these processes have been extensively analysed in the post-mitotic neurons, little is known about proliferating neuronal precursors. We have taken as a model of neuroblasts the embryonic hippocampal cell line HN9.10e. Apoptosis was induced by serum deprivation and by treatment with N-acetylsphingosine (C2-Cer), a membrane-permeant analogue of the second messenger ceramide. Following C2-Cer addition, cytochrome c was released from mitochondria, [Ca(2+)](i) and caspase-3-like activity increased. Both cytochrome c release and rise of [Ca(2+)](i) occurred before caspase-3 activation and nuclear condensation. The intracellular levels of ceramide peaked at 1h following the serum deprivation. These results indicate that the serum deprivation induces a rise in the intracellular ceramide level, and that increased ceramide concentration leads to calcium dysregulation and release of cytochrome c followed by caspase-3 activation. We show that cytochrome c is released without a loss of mitochondrial transmembrane potential.
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37
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Bilderback TR, Gazula VR, Dobrowsky RT. Phosphoinositide 3-kinase regulates crosstalk between Trk A tyrosine kinase and p75(NTR)-dependent sphingolipid signaling pathways. J Neurochem 2001; 76:1540-51. [PMID: 11238738 DOI: 10.1046/j.1471-4159.2001.00171.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mechanism of crosstalk between signaling pathways coupled to the Trk A and p75(NTR) neurotrophin receptors in PC12 cells was examined. In response to nerve growth factor (NGF), Trk A activation inhibited p75(NTR)-dependent sphingomyelin (SM) hydrolysis. The phosphoinositide 3-kinase (PI 3-kinase) inhibitor, LY294002, reversed this inhibition suggesting that Trk A activation of PI 3-kinase is necessary to inhibit sphingolipid signaling by p75(NTR). In contrast, SM hydrolysis induced by neurotrophin-3 (NT-3), which did not activate PI-3 kinase, was uneffected by LY294002. However, transient expression of a constituitively active PI 3-kinase inhibited p75(NTR)-dependent SM hydrolysis by both NGF and NT-3. Intriguingly, NGF induced an association of activated PI 3-kinase with acid sphingomyelinase (SMase). This interaction localized to caveolae-related domains and correlated with a 50% decrease in immunoprecipitated acid SMase activity. NGF-stimulated PI 3-kinase activity was necessary for inhibition of acid SMase but was not required for ligand-induced association of the p85 subunit of PI 3-kinase with the phospholipase. Finally, this interaction was specific for NGF since EGF did not induce an association of PI 3-kinase with acid SMase. In summary, our data suggest that PI 3-kinase regulates the inhibitory crosstalk between Trk A tyrosine kinase and p75(NTR)-dependent sphingolipid signaling pathways and that this interaction localizes to caveolae-related domains.
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Affiliation(s)
- T R Bilderback
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, Kansas, USA
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38
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Abstract
The important effect of cell death on projecting neurons during development is well established. However, this mainstream research might have diverted recognition of the cell death that occurs at earlier stages of neural development, affecting proliferating neural precursor cells and young neuroblasts. In this article, we briefly present observations supporting the occurrence of programmed cell death during early neural development in a regulated fashion that to some extent parallels the death of projecting neurons lacking neurotrophic support. These findings raise new questions, in particular the magnitude and the role of this early neural cell death.
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Affiliation(s)
- E J de la Rosa
- Dept of Cell and Developmental Biology, Centro de Investigaciones Biológicas, CSIC, Velázquez 144, E-28006, Madrid, Spain
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39
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Tavarini S, Colombaioni L, Garcia-Gil M. Sphingomyelinase metabolites control survival and apoptotic death in SH-SY5Y neuroblastoma cells. Neurosci Lett 2000; 285:185-8. [PMID: 10806317 DOI: 10.1016/s0304-3940(00)01054-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
There is increasing evidence that sphingolipids are involved in cell survival, differentiation or commitment to death. The effect of different sphingolipids and inhibitors of mitogen-activated protein kinase (MAPK) cascade on SH-SY5Y neuroblastoma cell death has been studied. Permeant ceramide analogues C2-Cer, C8-Cer, and C8-Cer-1-phosphate, but not dihydro C2-Cer induce apoptosis, as shown by Hoechst staining. Inhibition of ceramidase and sphingosine kinase, as well as incubation with sphingosine, decreases cell viability, measured as 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide reduction, whereas addition of sphingosine-1-phosphate increases proliferation. Both PD98059 (MAPKK inhibitor) and SB202190 (p38 MAPK inhibitor) decreased viability, but only SB202190 abolished the effect of ceramide. These results suggest that in SH-SY5Y neuroblastoma cells, death is signalled by increases in ceramide, ceramide-phosphate or sphingosine content through p38 MAPK pathway while survival requires MAPK and high sphingosine-1-phosphate/ceramide ratio.
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Affiliation(s)
- S Tavarini
- Departments of Physiology and Biochemistry, University of Pisa, via S. Zeno 31, 56127, Pisa, Italy
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40
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Huang T, Cheng AG, Stupak H, Liu W, Kim A, Staecker H, Lefebvre PP, Malgrange B, Kopke R, Moonen G, Van De Water TR. Oxidative stress-induced apoptosis of cochlear sensory cells: otoprotective strategies. Int J Dev Neurosci 2000; 18:259-70. [PMID: 10715580 DOI: 10.1016/s0736-5748(99)00094-5] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Apoptosis is an important process, both for normal development of the inner ear and for removal of oxidative-stress damaged sensory cells from the cochlea. Oxidative-stressors of auditory sensory cells include: loss of trophic factor support, ischemia-reperfusion, and ototoxins. Loss of trophic factor support and cisplatin ototoxicity, both initiate the intracellular production of reactive oxygen species and free radicals. The interaction of reactive oxygen species and free radicals with membrane phospholipids of auditory sensory cells creates aldehydic lipid peroxidation products. One of these aldehydes, 4-hydroxynonenal, functions as a mediator of apoptosis for both auditory neurons and hair cells. We present several approaches for the prevention of auditory sensory loss from reactive oxygen species-induced apoptosis: 1) preventing the formation of reactive oxygen species; (2) neutralizing the toxic products of membrane lipid peroxidation; and 3) blocking the damaged sensory cells' apoptotic pathway.
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Affiliation(s)
- T Huang
- Department of Otolaryngology, Albert Einstein College of Medicine, Bronx, New York, USA
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41
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Frade JM. Unscheduled re-entry into the cell cycle induced by NGF precedes cell death in nascent retinal neurones. J Cell Sci 2000; 113 ( Pt 7):1139-48. [PMID: 10704365 DOI: 10.1242/jcs.113.7.1139] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During their early postmitotic life, a proportion of the nascent retinal ganglion cells (RGCs) are induced to die as a result of the interaction of nerve growth factor (NGF) with the neurotrophin receptor p75. To analyse the mechanisms by which NGF promotes apoptosis, an in vitro culture system consisting of dissociated E5 retinal cells was established. In this system, NGF-induced apoptosis was only observed in the presence of insulin and neurotrophin-3, conditions that favour the birth of RGCs and other neurones expressing the glycoprotein G4. The pro-apoptotic effect of NGF on the G4-positive neurones was evident after 10 hours in vitro and was preceded by a significant upregulation of cyclin B2, but not cyclin D1, and the presence of mitotic nuclei in these cells. Brain-derived neurotrophic factor prevented both the increase of cyclin B2 expression in the G4-positive neurones and the NGF-induced cell death. Finally, pharmacologically blocking cell-cycle progression using the cyclin-dependent kinase inhibitor roscovitine prevented NGF-induced cell death in a dose-dependent manner. These results strongly suggest that the apoptotic signalling initiated by NGF requires a driving stimulus manifested by the neuronal birth and is preceded by the unscheduled re-entry of postmitotic neurones into the cell cycle.
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Affiliation(s)
- J M Frade
- Instituto Cajal de Neurobiología, CSIC, Avenida Doctor Arce 37, Madrid E28002, Spain.
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42
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Huang BR, Gu JJ, Ming H, Lai DB, Zhou XF. Differential actions of neurotrophins on apoptosis mediated by the low affinity neurotrophin receptor p75NTR in immortalised neuronal cell lines. Neurochem Int 2000; 36:55-65. [PMID: 10566959 DOI: 10.1016/s0197-0186(99)00098-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The low affinity neurotrophin receptor (p75NTR) mediates apoptosis of a number of neuronal and non-neuronal cells but the signals leading to the apoptosis remain obscure. To reveal the mechanism of p75NTR-mediated apoptosis, a neural cell line expressing human p75NTR was established. The human cDNA fragment encoding for p75NTR was PCR-amplified, cloned into the retrovirus expression vector pXT-1 and transfected into the rat cerebellum cell line R2. The expression of p75NTR in the R2 cell line was demonstrated by both Northern blotting analysis and immunocytochemistry. Serum withdrawal induced dramatic apoptosis in p75NTR-expressing R2 cells (R2L1) but not in pXT-1 transfected control R2 cells (R2P). Reverse transcription polymerase chain reaction (RT-PCR) revealed that these cell lines express trkA and trkB but not trkC. The apoptosis of R2L1 cells triggered by the serum deprivation for 48 h was completely prevented by neurotrophin-3 and the antibody to p75NTR but only partially prevented by the nerve growth factor and brain derived neurotrophic factor. We conclude that the p75NTR mediates apoptosis of R2L1 cells by its intrinsic receptor effects requiring an unbound status of this receptor and that the apoptosis is prevented by neurotrophins or the antibody to p75NTR through distinct mechanisms.
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Affiliation(s)
- B R Huang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing.
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43
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The interrelation between the biological functions of sphingolipids and their chemical structure. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2000. [DOI: 10.1007/bf02758855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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44
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Sanz C, León Y, Cañón S, Alvarez L, Giraldez F, Varela-Nieto I. Pattern of expression of the jun family of transcription factors during the early development of the inner ear: implications in apoptosis. J Cell Sci 1999; 112 ( Pt 22):3967-74. [PMID: 10547357 DOI: 10.1242/jcs.112.22.3967] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Jun transcription factors have been implicated in the regulation of cell proliferation, differentiation and apoptosis. We have investigated the relationship between Jun expression and cell death in the developing chicken inner ear. c-jun and junD transcripts were expressed in the epithelium of the otic placode and otic vesicle. c-jun expression was restricted to the dorsal area of the otic pit (stages 14–17), dorsal otic vesicle and cochleo-vestibular ganglion (stages 18–20). junD expression was transient and occurred in the dorsal and upper medial aspects of the otic pit and otic cup, but it was down-regulated in the otic vesicle. A parallel TUNEL analysis revealed that expression of c-jun co-located within areas of intense apoptosis. Furthermore, phosphorylation of c-Jun at serine-63 by Jun amino-terminal-kinases was detected in the dorsal otic pit, otic vesicle and cochleo-vestibular ganglion. c-Jun protein exhibited DNA binding activity, as assessed by gel mobility shift assays. The association between c-Jun and apoptosis was further demonstrated by studying nerve growth factor-induced apoptosis in cultured otic vesicles. Nerve growth factor-induced cell death and c-Jun phosphorylation that were suppressed by insulin-like growth factor-I and by viral-mediated overexpression of Raf, which had survival effects. In conclusion, the precise regulation of the expression and activity of Jun proteins in the otic primordium suggests that it may operate as a fundamental mechanism during organogenesis.
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Affiliation(s)
- C Sanz
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Arturo Duperier 4, Spain
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45
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Sedel F, Béchade C, Triller A. Nerve growth factor (NGF) induces motoneuron apoptosis in rat embryonic spinal cord in vitro. Eur J Neurosci 1999; 11:3904-12. [PMID: 10583479 DOI: 10.1046/j.1460-9568.1999.00814.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Recent studies have demonstrated that nerve growth factor (NGF) induces apoptosis of several cell types in the central nervous system through its low-affinity p75 neurotrophin receptor (p75NTR). To test the effect of NGF on embryonic motoneuron survival, we developed an organotypic culture system which allowed the in vitro development of intact embryonic rat spinal cords. In our system, neural tubes were taken and cultured at E13, just before the onset of physiological motoneuron death. After 2 days in vitro (DIV), motoneurons underwent apoptosis over a time-course similar to that in vivo. In this system, the addition of NGF (200 ng/mL) for 2 days enhanced the number of apoptotic motoneurons by 37%. This pro-apoptotic effect was completely reversed by the blocking anti-p75NTR (REX) antibody which inhibits NGF binding to p75NTR. Other neurotrophins, e.g. brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3) and neurotrophin 4/5 (NT4/5) did not have any effect, while glial cell-derived neurotrophic factor (GDNF) promoted motoneuron survival. Anti-BDNF blocking antibodies enhanced motoneuron death indicating that endogenous BDNF promotes motoneuron survival in explants. Our results demonstrate, for the first time, that NGF can induce embryonic motoneuron apoptosis through its receptor p75NTR.
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Affiliation(s)
- F Sedel
- Laboratoire de Biologie Cellulaire de la Synapse Normale et Pathologique (INSERM U497), Ecole Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France
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46
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Frade JM, Barde YA. Genetic evidence for cell death mediated by nerve growth factor and the neurotrophin receptor p75 in the developing mouse retina and spinal cord. Development 1999; 126:683-90. [PMID: 9895316 DOI: 10.1242/dev.126.4.683] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of nerve growth factor (NGF) and of the neurotrophin receptor p75 (p75(NTR)) in programmed cell death was investigated in the retina and the spinal cord of mouse embryos. Large numbers of cells express p75(NTR) in and along the developing optic nerve and in the mantle zone of the spinal cord. In embryos carrying deletions in the ngf or the p75(NTR) gene, cell death was reduced in the retina and in the spinal cord. Increased numbers of Islet-1-immunoreactive cells were detected in the dorsal spinal cord, and the mantle zone was enlarged in both mutants. These results indicate that NGF/p75(NTR)-dependent mechanisms are used to remove cells when axonal tracts elongate in developing neuroepithelia.
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Affiliation(s)
- J M Frade
- Max-Planck Institute of Neurobiology, Department of Neurobiochemistry, Am Klopferspitz 18a, D-82152 Germany
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47
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Sanz C, León Y, Troppmair J, Rapp UR, Varela-Nieto I. Strict regulation of c-Raf kinase levels is required for early organogenesis of the vertebrate inner ear. Oncogene 1999; 18:429-37. [PMID: 9927199 DOI: 10.1038/sj.onc.1202312] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Regulation of organogenesis involves a dynamic balance of the mechanisms regulating cell division, differentiation and death. Here we have investigated the pattern of expression of c-Raf kinase in the inner ear during early developmental stages and the consequences of manipulating c-Raf levels by misexpression of c-raf viral vectors in organotypic cultures of otic vesicle explants. We found that otic vesicles expressed c-Raf and its level remained constant during embryonic days 2 and 3 (E2-E3). c-Raf activity was increased in response to insulin like growth factor-I (IGF-I) and the activation by IGF-I of the c-Raf kinase pathway was a requirement to turn on cell proliferation in the otic vesicle. Overexpression of c-raf in E2.5 explants increased the proliferative response to low serum and IGF-I and blocked differentiation induced by retinoic acid. The increase in c-Raf levels also prevented nerve growth factor (NGF)-dependent induction of programmed cell death. Consistent with these results, the expression of a dominant negative c-Raf mutant potentiated retinoic acid action and decreased the rate of cell proliferation. We conclude that a strict control of c-Raf levels is essential for the co-ordination of the biological processes that operate simultaneously during early inner ear development.
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Affiliation(s)
- C Sanz
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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48
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León Y, Sanz C, Giráldez F, Varela-Nieto I. Induction of cell growth by insulin and insulin-like growth factor-I is associated with Jun expression in the otic vesicle. J Comp Neurol 1998; 398:323-32. [PMID: 9714146 DOI: 10.1002/(sici)1096-9861(19980831)398:3<323::aid-cne2>3.0.co;2-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The present report investigates the cellular mechanisms involved in the regulation of cell proliferation by insulin and insulin-like growth factor-I (IGF-I) in the developing inner ear. The results show that insulin and IGF-I stimulate cell proliferation in the otic vesicle. This effect is associated with the induction of the expression of the nuclear proto-oncogene c-jun. The temporal profile of Jun expression coincided with the proliferative period of growth of the otic vesicle. IGF-I promoted the hydrolysis of a membrane glycosyl-phosphatidylinositol, which was characterised as the endogenous precursor for inositol phosphoglycan (IPG). Both purified IPG and a synthetic analogue, 6-O-(2-amino-2-deoxy-alpha-D-glucopyranosyl)-D-myoinositol-1,2-cyclic phosphate (C3), were able to mimic the effects of IGF-I on Jun expression. Anti-IPG antibodies blocked the effects of IGF-I, which were rescued by the addition of IPG or its analogue. These results suggest that the sequence involving the hydrolysis of membrane glycolipids and the expression of c-jun and c-fos proto-oncogenes is part of the mechanism that activates cell division in response to insulin and IGF-I during early organogenesis of the avian inner ear. The implications of these observations for otic development and regeneration are briefly discussed.
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Affiliation(s)
- Y León
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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