101
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Ramström C, Chapman H, Ekokoski E, Tuominen RK, Pasternack M, Törnquist K. Tumor necrosis factor alpha and ceramide depolarise the resting membrane potential of thyroid FRTL-5 cells via a protein kinase Czeta-dependent regulation of K+ channels. Cell Signal 2005; 16:1417-24. [PMID: 15381257 DOI: 10.1016/j.cellsig.2004.05.007] [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: 01/26/2004] [Revised: 04/28/2004] [Accepted: 05/14/2004] [Indexed: 11/24/2022]
Abstract
Tumor necrosis factor alpha (TNFalpha) alters the electrophysiological properties of many cell types. In thyroid cells however, the effects have not yet been elucidated. Here, we report the effect of TNFalpha and its second messenger ceramide on the resting membrane potential (RMP) of thyroid FRTL-5 cells. In patch-clamp experiments, we showed that TNFalpha and ceramide depolarise the RMP by inhibiting an acid-sensitive inwardly rectifying potassium current. This depolarisation depended on the activation of protein kinase Czeta (PKCzeta), because it can be blocked by calphostin C, a PKC-inhibitory peptide and a specific inhibitor peptide for PKCzeta. The activation of PKCzeta was confirmed by Western blotting, in which a stimulation with TNFalpha led to the translocation of PKCzeta to the particulate fraction. We conclude that TNFalpha and ceramide depolarise the RMP of thyroid FRTL-5 cells by attenuating a Ba(2+)- and acid-sensitive potassium conductance via activation of PKCzeta.
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Affiliation(s)
- Cia Ramström
- Department of Biology, Abo Akademi University, BioCity, Artillerigatan 6, 20520, Turku, Finland
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102
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Akundi RS, Candelario-Jalil E, Hess S, Hüll M, Lieb K, Gebicke-Haerter PJ, Fiebich BL. Signal transduction pathways regulating cyclooxygenase-2 in lipopolysaccharide-activated primary rat microglia. Glia 2005; 51:199-208. [PMID: 15800925 DOI: 10.1002/glia.20198] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Microglia are the major cell type involved in neuroinflammatory events in brain diseases such as encephalitis, stroke, and neurodegenerative disorders, and contribute significantly to the release of prostaglandins (PGs) during neuronal insults. In this report, we studied the immediate-early intracellular signalling pathways in microglia, following bacterial lipopolysaccharide (LPS) stimulation, leading to the synthesis and release of PGE2. Here we show that LPS induces cyclooxygenase (COX) 2 by activating sphingomyelinases leading to the release of ceramides, which in turn, activate the p38 mitogen-activated protein kinases (MAPK), but not the p42/44 MAPK. We further show that exogenously added ceramide analogue (C2-ceramide) also induce PGE2 synthesis through a p38 MAPK-dependent pathway. This potential nature of ceramides in activating microglia suggests that endogenously produced ceramides during neuronal apoptosis in ischemia or neurodegenerative diseases could also contribute to the amplification of neuroinflammatory events. In contrast to protein kinase C (PKC) and phosphocholine-specific phospholipase C (PC-PLC), which transcriptionally regulate LPS-induced COX-2 synthesis, inhibition of phospholipase A2 (PLA2) has no effect on COX-2 transcription, although it inhibits the release of PGE2. Transcriptional regulation of LPS-induced COX-2 by PKC is further proved by the ability of the PKC inhibitor, Gö 6976, to inhibit LPS-induced 8-isoprostane synthesis, but not affecting LPS-induced COX-2 activity. Our data with 8-isoprostane also indicates that COX-2 plays a major role in ROS production in LPS-activated microglia. This detailed view of the intracellular signaling pathway in microglial activation and COX-2 expression opens a new therapeutic window in the search for new and more effective central anti-inflammatory agents.
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Affiliation(s)
- Ravi Shankar Akundi
- Department of Psychiatry, University of Freiburg Medical School, Freiburg, Germany
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103
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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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104
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Zhang YH, Nicol GD. NGF-mediated sensitization of the excitability of rat sensory neurons is prevented by a blocking antibody to the p75 neurotrophin receptor. Neurosci Lett 2004; 366:187-92. [PMID: 15276244 DOI: 10.1016/j.neulet.2004.05.042] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 05/12/2004] [Accepted: 05/15/2004] [Indexed: 12/21/2022]
Abstract
Nerve growth factor (NGF) can play a causal role in the initiation of hyperalgesia. Recent work demonstrates that NGF can act directly on nociceptive sensory neurons to augment their sensitivity to a variety of stimuli. Based on the existing literature, it is not clear whether this sensitization is mediated by the high-affinity TrkA receptor or the low-affinity p75 neurotrophin receptor. We examined whether a blocking antibody to the p75 neurotrophin receptor can prevent the NGF-induced enhancement of excitability in capsaicin-sensitive small-diameter sensory neurons that have been isolated from the adult rat. In this report, pretreatment with the p75 blocking antibody completely prevents the NGF-induced increase in the number of action potentials evoked by a ramp of depolarizing current as well as the suppression of a delayed rectifier-type of potassium current(s) in these neurons. Although the sensitization by NGF was blocked, the antibody had no effect on the capacity of ceramide, a putative downstream signaling molecule, to either enhance the excitability or inhibit the potassium current. These results indicate that NGF can increase the excitability of nociceptive sensory neurons through activation of the p75 neurotrophin receptor and its consequent liberation of ceramide from neuronal sphingomyelins.
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Affiliation(s)
- Y H Zhang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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105
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Abstract
INTRODUCTION The nerve growth factor (NGF) is known as a factor involved in neuronal growth and survival. From recent studies it may also be considered as a mediator of inflammation, in particular in the airways. STATE OF ART Several animal studies have shown that NGF may increase the sensory innervation, and participate in the bronchial hyperresponsiveness and inflammation observed in the airways of asthmatic patients. Different cell types are capable of secreting NGF: inflammatory cells that infiltrate the bronchial mucosa, and structural cells such as epithelial cells, smooth muscle cells and pulmonary fibroblasts. Furthermore, increased NGF levels have been detected in the bronchoalveolar lavage fluid from asthmatic patients. PERSPECTIVES AND CONCLUSION Altogether, these results suggest that NGF may play a role in inflammation, bronchial hyperresponsiveness and airway remodelling in asthma, and may lead to a better understanding of the mechanisms occurring in chronic inflammatory diseases, in particular asthma.
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Affiliation(s)
- V Freund
- EA 3771 Inflammation et environnement dans l'asthme, Université Louis Pasteur-Strasbourg-I, Faculté de Pharmacie, Illkirch, France
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106
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Zhou S, Cao JM, Swissa M, Gonzalez-Gomez I, Chang CM, Chien K, Miyauchi Y, Fu KJ, Yi J, Asotra K, Karagueuzian HS, Fishbein MC, Chen PS, Chen LS. Low-affinity nerve growth factor receptor p75NTR immunoreactivity in the myocardium with sympathetic hyperinnervation. J Cardiovasc Electrophysiol 2004; 15:430-7. [PMID: 15089992 DOI: 10.1046/j.1540-8167.2004.03517.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION We previously demonstrated the relationship between sympathetic nerve density in myocardium and the occurrences of ventricular arrhythmia. Nerve growth factor (NGF) regulates myocardial sympathetic innervation. However, it is unclear whether the NGF high-affinity receptor tyrosine kinase A (TrkA) and the NGF low-affinity receptor p75NTR are altered in the state of sympathetic hyperinnervation in the heart. The aim of this study was to determine the density and location of TrkA and p75NTR in canine ventricles with sympathetic hyperinnervation. METHODS AND RESULTS Myocardial sympathetic hyperinnervation was induced by local infusion of NGF into myocardium or left stellate ganglia, or chronic subthreshold electric stimulation to the left stellate ganglia. The results showed that TrkA immunoreactivity was absent in the myocardium. Low-affinity receptor p75NTR immunoreactivity was present in axons, Schwann cells, and interstitial cells of sympathetic nerves, as well as in interstitial cells of the myocardium. The density of p75NTR immunolabeled myocardial interstitial cells at the NGF infusion site was lower than that at the site remote from NGF infusion, yet the sympathetic nerve density was higher at the infusion site than the remote area. The density of p75NTR also was lower in the myocardium with high sympathetic nerve density, induced by NGF infusion or chronic electric stimulation of the left stellate ganglia, compared to control groups. CONCLUSION The data indicate that p75NTR may be the main NGF receptor in the myocardium, and p75NTR immunopositive interstitial cells may have a role in regulating sympathetic nerve growth in canine heart.
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Affiliation(s)
- Shengmei Zhou
- Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
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107
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Srinivasan B, Roque CH, Hempstead BL, Al-Ubaidi MR, Roque RS. Microglia-derived pronerve growth factor promotes photoreceptor cell death via p75 neurotrophin receptor. J Biol Chem 2004; 279:41839-45. [PMID: 15277529 DOI: 10.1074/jbc.m402872200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reports implicating microglia-derived nerve growth factor (NGF) during programmed cell death in the developing chick retina led us to investigate its possible role in degenerative retinal disease. Freshly isolated activated retinal microglia expressed high molecular weight forms of neurotrophins including that of nerve growth factor (NGF), brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-4. Conditioned media from cultured retinal microglia (MGCM) consistently yielded a approximately 32-kDa NGF-reactive band when supplemented with bovine serum albumin (BSA) or protease inhibitors (PI); and promoted cell death that was suppressed by NGF immunodepletion in a mouse photoreceptor cell line (661w). The approximately 32 kDa protein was partially purified (MGCM/p32) and was highly immunoreactive with a polyclonal anti-pro-NGF antibody. Both MGCM/p32 and recombinant pro-NGF protein promoted cell death in 661w cultures. Increased levels of pro-NGF mRNA and protein were observed in the RCS rat model of retinal dystrophy. MGCM-mediated cell death was reversed by p75NTR antiserum in p75NTR(+)/trkA(-) 661w cells. Our study shows that a approximately 32 kDa pro-NGF protein released by activated retinal microglia promoted degeneration of cultured photoreceptor cells. Moreover, our study suggests that defective post-translational processing of NGF might be involved in photoreceptor cell loss in retinal dystrophy.
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Affiliation(s)
- Bhooma Srinivasan
- Department of Cell Biology and Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
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108
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Denkins Y, Reiland J, Roy M, Sinnappah-Kang ND, Galjour J, Murry BP, Blust J, Aucoin R, Marchetti D. Brain metastases in melanoma: roles of neurotrophins. Neuro Oncol 2004; 6:154-65. [PMID: 15134630 PMCID: PMC1871977 DOI: 10.1215/s115285170300067x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2003] [Accepted: 12/11/2003] [Indexed: 01/31/2023] Open
Abstract
Brain metastasis, which occurs in 20% to 40% of all cancer patients, is an important cause of neoplastic morbidity and mortality. Successful invasion into the brain by tumor cells must include attachment to microvessel endothelial cells, penetration through the blood-brain barrier, and, of relevance, a response to brain survival and growth factors. Neurotrophins (NTs) are important in brain-invasive steps. Human melanoma cell lines express low-affinity NT receptor p75NTR in relation to their brain-metastatic propensity with their invasive properties being regulated by NGF, or nerve growth factor, the prototypic NT. They also express functional TrkC, the putative receptor for the invasion-promoting NT-3. In brain-metastatic melanoma cells, NTs promote invasion by enhancing the production of extracellular matrix (ECM)-degradative enzymes such as heparanase, an enzyme capable of locally destroying both ECM and the basement membrane of the blood-brain barrier. Heparanase is an endo-beta-d-glucuronidase that cleaves heparan sulfate (HS) chains of ECM HS proteoglycans, and it is a unique metastatic determinant because it is the dominant mammalian HS degradative enzyme. Brain-metastatic melanoma cells also produce autocrine/paracrine factors that influence their growth, invasion, and survival in the brain. Synthesis of these factors may serve to regulate NT production by brain cells adjacent to the neoplastic invasion front, such as astrocytes. Increased NT levels have been observed in tumor-adjacent tissues at the invasion front of human brain melanoma. Additionally, astrocytes may contribute to the brain-metastatic specificity of melanoma cells by producing NT-regulated heparanase. Trophic, autocrine, and paracrine growth factors may therefore determine whether metastatic cells can successfully invade, colonize, and grow in the CNS.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Dario Marchetti
- Address correspondence to Dario Marchetti, Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Skip Bertman Drive, Room 2522, Louisiana State University-Baton Rouge, Baton Rouge, LA 70803, USA (
)
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109
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Graiani G, Emanueli C, Desortes E, Van Linthout S, Pinna A, Figueroa CD, Manni L, Madeddu P. Nerve growth factor promotes reparative angiogenesis and inhibits endothelial apoptosis in cutaneous wounds of Type 1 diabetic mice. Diabetologia 2004; 47:1047-54. [PMID: 15164170 DOI: 10.1007/s00125-004-1414-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Accepted: 02/27/2004] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS The neurotrophin nerve growth factor (NGF) is pro-angiogenic and facilitates wound repair. The present study was conducted to (i) assess the statement of NGF system components in diabetic wounds and (ii) evaluate whether NGF supplementation could prevent impairment of wound neoangiogenesis by diabetes. METHODS Skin wounds were produced in the interscapular region of streptozotocin-induced diabetic mice. NGF (1 microg per day in PBS) or vehicle was applied onto the ulcers for 3 days after punching. Non-diabetic mice were used as controls. RESULTS In wounds of untreated diabetic mice, endogenous levels of immunoreactive NGF were lower than those in wounds of non-diabetic mice ( p<0.01). Immunohistochemical analysis showed down-regulation of tyrosine kinase receptor-A (TrkA) and up-regulation of p75 receptor in granulation tissue microvasculature. Local NFG administration prevented diabetes-induced expressional alterations, enhanced reparative capillarisation ( p<0.01), and accelerated wound closure ( p<0.01). This was associated with a three-fold increase in endothelial cell proliferation ( p<0.01), while apoptosis was reduced by 50% ( p<0.05). Quantitative RT-PCR documented a 5.5-fold increase in the expression of vascular endothelial growth factor-A (VEGF-A) by exogenous NGF in diabetic tissues ( p<0.01). In in vitro preparations of human endothelial cells from derma, NGF increased the release of immunoreactive VEGF-A, and reduced high-glucose-induced apoptosis ( p<0.05), the latter effect being inhibited by a VEGF-A receptor-2 antagonist. CONCLUSIONS/INTERPRETATION Diabetic ulcers display distinct alterations in reparative angiogenesis and in the expression of NGF and its receptors. NGF supplementation corrects endogenous liabilities, facilitates vascular regeneration, and suppresses endothelial apoptosis seemingly via VEGF-A. Our findings unravel new mechanisms responsible for NGF reparative action.
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MESH Headings
- Administration, Cutaneous
- Animals
- Apoptosis/drug effects
- Cell Proliferation/drug effects
- Cells, Cultured
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Type 1/complications
- Disease Models, Animal
- Drug Evaluation, Preclinical/methods
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Endothelial Cells/pathology
- Gene Expression/drug effects
- Glucose/adverse effects
- Glucose/antagonists & inhibitors
- Glucose/metabolism
- Humans
- Italy
- Male
- Mice
- Neovascularization, Physiologic/drug effects
- Neovascularization, Physiologic/physiology
- Nerve Growth Factor/genetics
- Nerve Growth Factor/metabolism
- Nerve Growth Factor/therapeutic use
- Receptors, Nerve Growth Factor/drug effects
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/metabolism
- Skin Ulcer/complications
- Skin Ulcer/drug therapy
- Skin Ulcer/pathology
- Vascular Endothelial Growth Factor A/drug effects
- Vascular Endothelial Growth Factor A/genetics
- Vascular Endothelial Growth Factor A/metabolism
- Wound Healing/drug effects
- Wound Healing/physiology
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Affiliation(s)
- G Graiani
- Department of Pathology, University of Parma, Italy
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110
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Coulson EJ, Reid K, Shipham KM, Morley S, Kilpatrick TJ, Bartlett PF. The role of neurotransmission and the Chopper domain in p75 neurotrophin receptor death signaling. PROGRESS IN BRAIN RESEARCH 2004; 146:41-62. [PMID: 14699955 DOI: 10.1016/s0079-6123(03)46003-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The role of p75 neurotrophin receptor (p75NTR) in mediating cell death is now well characterized, however, it is only recently that details of the death signaling pathway have become clearer. This review focuses on the importance of the juxtamembrane Chopper domain region of p75NTR in this process. Evidence supporting the involvement of K+ efflux, the apoptosome (caspase-9, apoptosis activating factor-1, APAF-1, and Bcl-xL), caspase-3, c-jun kinase, and p53 in the p75NTR cell death pathway is discussed and regulatory roles for the p75NTR ectodomain and death domain are proposed. The role of synaptic activity is also discussed, in particular the importance of neutrotransmitter-activated K+ channels acting as the gatekeepers of cell survival decisions during development and in neurodegenerative conditions.
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Affiliation(s)
- E J Coulson
- Queensland Brain Institute, University of Queensland, Brisbane, Qld, Australia.
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111
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Plo I, Bono F, Bezombes C, Alam A, Bruno A, Laurent G. Nerve growth factor-induced protein kinase C stimulation contributes to TrkA-dependent inhibition of p75 neurotrophin receptor sphingolipid signaling. J Neurosci Res 2004; 77:465-74. [PMID: 15264216 DOI: 10.1002/jnr.20189] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Previous studies have established that reciprocal interactions between the low-affinity p75 nerve growth factor (NGF) receptor (p75(NTR)) and the high-affinity TrkA NGF receptor can dictate the cellular response to NGF. As the most important interaction, TrkA signaling was found to inhibit p75(NTR)-mediated sphingomyelinase (SMase) stimulation, ceramide production, and apoptosis. However, the mechanism by which TrkA counteracts p75(NTR)-coupled sphingolipid signaling is still unclear. Considering the stimulatory effect of NGF on protein kinase C (PKC) activity, we investigated the role of PKC in TrkA/p75(NTR) signaling interaction. In this study, we found that, in SK-N-BE cells, which selectively express p75(NTR), phorbol ester-induced PKC stimulation resulted in the abrogation of SMase stimulation and ceramide production induced by NGF. Moreover, in SK-N-BE neuroblastoma cells, which selectively express TrkA, NGF stimulated global PKC activity through two independent pathways involving phospholipase Cgamma (PLCgamma) and phosphoinositide-3 kinase (PI3K). In SH-SY5Y, another neuroblastoma cell line, which coexpresses TrkA and p75(NTR), NGF induced PKC stimulation through a TrkA/PI3K signaling pathway, whereas there was no ceramide production. However, in these cells, the inhibition of TrkA, PI3K, and PKC resulted in the restoration of NGF-induced ceramide production. Thus, our study demonstrates for the first time that TrkA interferes with p75(NTR) signaling through a PI3K/PKC-dependent mechanism.
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Affiliation(s)
- I Plo
- INSERM U-563, Institut Claudius Regaud, Toulouse, France.
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112
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Hasegawa Y, Yamagishi S, Fujitani M, Yamashita T. p75 neurotrophin receptor signaling in the nervous system. BIOTECHNOLOGY ANNUAL REVIEW 2004; 10:123-49. [PMID: 15504705 DOI: 10.1016/s1387-2656(04)10005-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The neurotrophin receptor p75(NTR) has long been known as a receptor for neurotrophins that promote survival and differentiation. Consistent with the role of neurotrophins, p75(NTR) is expressed during the developmental stages of the nervous system. However, p75(NTR) is re-expressed in various pathological conditions in the adult. We now know that p75(NTR) has the ability to elicit bi-directional signals, that result in the inhibition as well as the promotion of the neurite outgrowth. p75(NTR) is a key receptor for myelin-derived inhibitory cues that contribute to the lack of regeneration of the central nervous system.
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Affiliation(s)
- Yuiko Hasegawa
- Department of Neurobiology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
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113
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Trapp BD. Pathogenesis of multiple sclerosis: The eyes only see what the mind is prepared to comprehend. Ann Neurol 2004; 55:455-7. [PMID: 15048883 DOI: 10.1002/ana.20087] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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114
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Mamidipudi V, Lin C, Seibenhener ML, Wooten MW. Regulation of interleukin receptor-associated kinase (IRAK) phosphorylation and signaling by iota protein kinase C. J Biol Chem 2003; 279:4161-5. [PMID: 14684752 DOI: 10.1074/jbc.c300431200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously shown that the activity of the interleukin-1 (IL-1) receptor-associated kinase (IRAK) is required for nerve growth factor (NGF)-induced activation of NF-kappaB and cell survival ((2002) J. Biol. Chem. 277, 28010-28018). Herein we demonstrate that NGF induces co-association of IRAK with atypical protein kinase C iota (PKC) and that the iota PKC.IRAK complex is recruited to the p75 neurotrophin receptor. Recruitment of IRAK to the receptor was dependent upon the activity of the iota PKC. Moreover, transfection of kinase-dead iota PKC blocked both NGF- and IL-1-induced IRAK activation and the activity of NF-kappaB. Hence, iota PKC lies upstream of IRAK in the kappaB pathway. Examining the primary structure of IRAK, we identified three putative PKC phosphorylation sites; iota PKC selectively phosphorylated peptide 1 (RTAS) within the death domain domain at Thr66, which is highly conserved among all IRAK family members. Mutation of Thr66 to Ala impaired the autokinase activity of IRAK and reduced its association with iota PKC but not TRAF6, resulting in impaired NGF- as well as IL-1-induced NF-kappaB activation. These findings provide insight into the underlying mechanism whereby IRAK regulates the kappaB pathway and reveal that IRAK is a substrate of iota PKC.
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Affiliation(s)
- Vidya Mamidipudi
- Program in Cell and Molecular Biosciences, Department of Biological Sciences, Auburn University, Auburn, Alabama 36849, USA
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115
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Song MS, Posse de Chaves EI. Inhibition of rat sympathetic neuron apoptosis by ceramide. Role of p75NTR in ceramide generation. Neuropharmacology 2003; 45:1130-50. [PMID: 14614956 DOI: 10.1016/s0028-3908(03)00284-3] [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: 11/23/2022]
Abstract
C6-ceramide protects sympathetic neurons from apoptosis caused by nerve growth factor (NGF) deprivation. Here, we report for the first time that ceramide generated "de novo" is also anti-apoptotic. Moreover, C6-ceramide is converted to long-chain ceramides in a process inhibited by fumonisin B1. The anti-apoptotic effect of C6-ceramide is due to the short analogue as to the long-chain ceramides. C6-ceramide shares mechanisms of action with NGF. C6-ceramide induces TrkA phosphorylation and selective activation of the phosphatidyl inositol 3-kinase (PI3-kinase)/Akt pathway but not the MAPK/ERK pathway. Importantly, the PI3-kinase inhibitor LY294002 abolishes the pro-survival effect of C6-ceramide. We identified a novel way to activate retrograde-mediated neuronal survival in the absence of NGF. Using compartmented cultures we show that addition of C6-ceramide exclusively to distal axons is sufficient to abort nuclear apoptosis. Our system offers a very unique alternative to understand the molecular bases of retrograde signaling in the absence of retrograde transport of neurotrophins. In search for a natural ligand that leads to ceramide generation we examined the activation of the sphingomyelin (SM) cycle downstream the p75 neurotrophin receptor (p75NTR). We found that in sympathetic neurons, selective activation of p75NTR by brain-derived neurotrophin factor or NGF plus K252a induces elevation of ceramide that correlates with SM hydrolysis. However, p75NTR activation does not generate sufficient ceramide to block apoptosis probably due to the rapid decrease in p75NTR expression that occurs upon NGF withdrawal.
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Affiliation(s)
- Mee-Sook Song
- Signal Transduction Research Group and Department of Pharmacology, Faculty of Medicine, University of Alberta, 928 Medical Science Building, Edmonton, Alta, Canada T6G 2S2
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116
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Krizsan-Agbas D, Pedchenko T, Hasan W, Smith PG. Oestrogen regulates sympathetic neurite outgrowth by modulating brain derived neurotrophic factor synthesis and release by the rodent uterus. Eur J Neurosci 2003; 18:2760-8. [PMID: 14656325 DOI: 10.1111/j.1460-9568.2003.03029.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Sympathetic innervation of the adult rodent uterus undergoes cyclic remodelling. Terminal sympathetic axons degenerate when oestrogen levels rise and regenerate when oestrogen levels decline. This study examined the role of neurotrophins in oestrogen-mediated uterine sympathetic nerve remodelling. Oestrogen injection of ovariectomized female rats did not affect uterine NT-3 levels 24 h postinjection, and increased endometrial NGF protein, indicating that reduced NGF or NT-3 is not responsible for the oestrogen-induced denervation. Oestrogen also raised BDNF protein and mRNA in myometrium and endometrium. To assess whether increased BDNF affects uterine receptivity to sympathetic outgrowth, sympathetic ganglion explants were co-cultured with myometrium. Myometrium from ovariectomized rats induced neuritogenesis in oestrogen-free conditions, and this was abolished when BDNF was added to the medium. Neuritogenesis induced by ovariectomized myometrium was suppressed by oestrogen, and restored by a BDNF function-blocking antibody. To determine if target BDNF synthesis is required for oestrogen to suppress sympathetic neurite outgrowth, uteri from wild-type mice and mice homozygous or heterozygous for recombinant mutations of the BDNF gene were cultured with rat sympathetic ganglia. Neuritogenesis induced by wild-type uteri was diminished by oestrogen. Neurite formation in the presence of homozygous BDNF mutant uteri was not affected by oestrogen, but was lower than that of wild-type mice. Uteri from mice heterozygous for the BDNF mutation, who have reduced BDNF synthesis, showed normal neuritogenic properties, but were not affected by oestrogen. These findings suggest that oestrogen alters neuritogenic properties of the rodent uterus by regulating BDNF synthesis, which inhibits sympathetic neurite outgrowth.
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Affiliation(s)
- D Krizsan-Agbas
- Department of Molecular and Integrative Physiology, Kansas University Medical Center, Kansas City, KS 66160, USA
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117
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Numakawa T, Nakayama H, Suzuki S, Kubo T, Nara F, Numakawa Y, Yokomaku D, Araki T, Ishimoto T, Ogura A, Taguchi T. Nerve growth factor-induced glutamate release is via p75 receptor, ceramide, and Ca(2+) from ryanodine receptor in developing cerebellar neurons. J Biol Chem 2003; 278:41259-69. [PMID: 12902347 DOI: 10.1074/jbc.m304409200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Very little is known about the contribution of a low affinity neurotrophin receptor, p75, to neurotransmitter release. Here we show that nerve growth factor (NGF) induced a rapid release of glutamate and an increase of Ca2+ in cerebellar neurons through a p75-dependent pathway. The NGF-induced release occurred even in the presence of the Trk inhibitor K252a. The release caused by NGF but not brain-derived neurotrophic factor was enhanced in neurons overexpressing p75. Further, after transfection of p75-small interfering RNA, which down-regulated the endogenous p75 expression, the NGF-induced release was inhibited, suggesting that the NGF-induced glutamate release was through p75. We found that the NGF-increased Ca2+ was derived from the ryanodine-sensitive Ca2+ receptor and that the NGF-increased Ca2+ was essential for the NGF-induced glutamate release. Furthermore, scyphostatin, a sphingomyelinase inhibitor, blocked the NGF-dependent Ca2+ increase and glutamate release, suggesting that a ceramide produced by sphingomyelinase was required for the NGF-stimulated Ca2+ increase and glutamate release. This action of NGF only occurred in developing neurons whereas the brain-derived neurotrophic factor-mediated Ca2+ increase and glutamate release was observed at the mature neuronal stage. Thus, we demonstrate that NGF-mediated neurotransmitter release via the p75-dependent pathway has an important role in developing neurons.
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Affiliation(s)
- Tadahiro Numakawa
- Neuronics R G Special Division for Human Life Technology National Institute of Advanced Industrial Science and Technology (AIST) Midorigaoka, Ikeda, Osaka 563-8577, Japan.
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118
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Okudaira C, Ikeda Y, Kondo S, Furuya S, Hirabayashi Y, Koyano T, Saito Y, Umezawa K. Inhibition of acidic sphingomyelinase by xanthone compounds isolated from Garcinia speciosa. JOURNAL OF ENZYME INHIBITION 2003; 15:129-38. [PMID: 10938539 DOI: 10.1080/14756360009030346] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Sphingomyelinase is considered to be involved in the regulation of apoptosis and cell growth. In the course of our screening for acidic sphingomyelinase inhibitors we isolated three xanthone compounds, alpha-mangostin, cowanin, and cowanol, from the bark of Garcinia speciosa. These compounds competitively inhibited bovine brain-derived acidic sphingomyelinase with IC(50) values of 14.1, 19.2, and 10.9 microM, respectively and inhibited the acidic sphingomyelinase more effectively than the neutral sphingomyelinase of bovine brain. alpha-Mangostin inhibited the acidic sphingomyelinase in the most selective manner. alpha-Mangostin was chemically modified and its structure-activity relationships are discussed.
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Affiliation(s)
- C Okudaira
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-0061, Japan
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119
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Choi MS, Anderson MA, Zhang Z, Zimonjic DB, Popescu N, Mukherjee AB. Neutral ceramidase gene: role in regulating ceramide-induced apoptosis. Gene 2003; 315:113-22. [PMID: 14557071 DOI: 10.1016/s0378-1119(03)00721-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The sphingolipid, ceramide, is a natural dietary constituent and a potent mediator of apoptosis. If left undegraded, it may induce apoptosis and cause disruption of cellular integrity. A potential mechanism to prevent ceramide-induced apoptosis in various organs may involve ceramidases that facilitate the degradation of ceramide. In this study, we first isolated and characterized the murine neutral ceramidase (N-CDase) gene, mapped its chromosomal location and determined its developmental and organ-specific expression. Then we used cultured mesangial cells as our in vitro model and mouse gastrointestinal (GI) tract as the in vivo model to determine the effects of an inhibitor of N-CDase, D-erythro-MAPP, to delineate whether N-CDase plays a role in preventing ceramide-induced apoptosis. Our results show that: (i) the structure of the murine neutral ceramidase gene is virtually identical to that of the human gene; (ii) it is localized on chromosome 19 at bands C2-C3 that is syntenic to human chromosome 10q24-26; (iii) N-CDase expression is developmentally regulated and it is expressed at high levels in cultured mesangial cells and in specific regions of the mouse small intestine; (iv) inhibition of N-CDase by D-erythro-MAPP leads to increased ceramide levels and consequent apoptosis in cultured mesangial cells; (v) mice treated with D-erythro-MAPP alone also caused apoptosis in the small intestine; and (vi) mice treated with D-erythro-MAPP prior to feeding C2 ceramide manifest markedly elevated levels of apoptosis in the GI tract raising the possibility that neutral ceramidase plays a detoxifying role against inadvertent stimulation of ceramide-induced apoptosis in organs that come in contact with this sphingolipid. We propose that N-CDase is an essential component of an innate detoxifying mechanism to prevent ceramide-induced apoptosis.
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MESH Headings
- Amidohydrolases/antagonists & inhibitors
- Amidohydrolases/genetics
- Amidohydrolases/physiology
- Animals
- Apoptosis/drug effects
- Base Sequence
- Blotting, Northern
- Blotting, Western
- Cell Line
- Ceramidases
- Ceramides/metabolism
- Ceramides/pharmacology
- Chromosome Mapping
- Dose-Response Relationship, Drug
- Exons
- Gene Expression
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Enzymologic
- Genes/genetics
- Humans
- In Situ Hybridization, Fluorescence
- In Situ Nick-End Labeling
- Introns
- Male
- Mice
- Mice, Inbred C57BL
- Mitochondria/enzymology
- Molecular Sequence Data
- Myristates/pharmacology
- Neutral Ceramidase
- Propanolamines/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Analysis, DNA
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Affiliation(s)
- Moonsuk S Choi
- Section on Developmental Genetics, Heritable Disorders Branch, The National Institute of Child Health and Human Development, The National Institutes of Health, Room 9S241, Building 10, Bethesda, MD 20892-1830, USA
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120
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Abstract
The neurotrophin receptor p75NTR can induce signal transduction both in vivo and in vitro. The mechanisms by which p75NTR transduces signals have remained mostly unknown. Using yeast two-hybrid system, we identified the Ran-binding protein (RanBPM) as an interactor with the intracytoplasmic domain of p75NTR (p75ICD). The interaction was then validated by immunoprecipitation in mammalian cells and immunoblotting analysis. The domain in p75ICD interacting with RanBPM was mapped to the death domain.
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Affiliation(s)
- Dong Bai
- National Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
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121
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Eto M, Bennouna J, Hunter OC, Hershberger PA, Kanto T, Johnson CS, Lotze MT, Amoscato AA. C16 ceramide accumulates following androgen ablation in LNCaP prostate cancer cells. Prostate 2003; 57:66-79. [PMID: 12886525 DOI: 10.1002/pros.10275] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Adenocarcinoma of the prostate is the most frequently diagnosed non-cutaneous cancer and the second leading cause of cancer-related deaths among men in the United States. The most successful therapies to date for this tumor have involved some form of androgen ablation. However, these therapies become ineffective as the tumor evolves to an androgen-insensitive state. Ceramide is a lipid second messenger that has been shown to mediate growth arrest or cell death when added exogenously to prostate cancer cells. As a first step toward understanding the events that lead to the transition of prostate cancer cells to an androgen-independent state, we considered investigating the effect of androgen ablation on endogenous ceramide levels in androgen-sensitive and androgen-insensitive prostate cancer cells. METHODS To investigate the mechanisms of growth arrest/apoptosis in androgen-sensitive (LNCaP) and insensitive (DU-145, PC-3) cells, we used various methods including nonyl acridine orange (NAO) staining, propidium iodide (PI) staining/cell-cycle analysis, lipid analysis, and Western blotting assays. RESULTS In this study, we demonstrate that androgen ablation drives G(0)/G(1)-phase cell-cycle arrest followed by progressive apoptosis in vitro, in LNCaP cells. Lipid analysis indicated an increase in C16 ceramide, which was generated via the de novo pathway as revealed by blockade of ceramide synthase by fumonisin B1. The addition of 5alpha-dihydrotestosterone (DHT) or fumonisin B1 rescued LNCaP cells from apoptosis induced by androgen ablation, and decreased levels of intracellular C16 ceramide. Neither apoptosis nor an increase in C16 ceramide was observed in androgen-independent cell lines following androgen ablation.
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Affiliation(s)
- Masatoshi Eto
- Department of Surgery/Division of Biological Therapeutics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15219, USA
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122
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Lad SP, Neet KE. Activation of the mitogen-activated protein kinase pathway through p75NTR: a common mechanism for the neurotrophin family. J Neurosci Res 2003; 73:614-26. [PMID: 12929129 DOI: 10.1002/jnr.10695] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Neurotrophins interact with two distinct classes of cell-surface receptors, the Trk receptor tyrosine kinase family and the common neurotrophin receptor p75(NTR). For many years, the biological role of p75(NTR) remained obscure, being relegated to modulating Trk binding of neurotrophins. Recently, the importance of p75(NTR) as a signaling receptor in itself has become increasingly clear. The signals initiated by p75(NTR) are likely to be as complex as those for the Trk family and probably depend on the cell system in which such signaling is being studied. In this study, all members of the neurotrophin family were demonstrated to be capable of stimulating p75(NTR)-mediated activation of the mitogen-activated protein kinase (MAPK) family (ERK1,2). This activation is rapid and transient, peaking at 5-15 min, depending on the cell system. The classical MAPK cascade consists of the reaction series Ras-Raf-MEK-MAPK. The p75(NTR)-induced MAPK activation is MEK dependent but Raf independent. This result implies that neurotrophin activation of p75(NTR) results in some cascade (as yet unknown) that bypasses Raf and converges on MEK to result in activation of MAPK. This activated MAPK is then able to translocate to the nucleus. The effect of this MAPK activation on cell survival is dependent on cell type. These results support the concept that signaling from the p75(NTR) receptor is more diverse and extensive than previously believed.
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Affiliation(s)
- Shivanand P Lad
- Department of Biochemistry and Molecular Biology, Finch University of Health Sciences/The Chicago Medical School, North Chicago, Illinois 60064, USA
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123
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p75 neurotrophin receptor protects primary cultures of human neurons against extracellular amyloid beta peptide cytotoxicity. J Neurosci 2003. [PMID: 12917374 DOI: 10.1523/jneurosci.23-19-07385.2003] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The cytotoxicity of extracellular amyloid beta peptide (Abeta) has been clearly demonstrated in many cell types. In contrast, primary human neurons in culture are resistant to extracellular Abeta-mediated toxicity. Here, we investigate the involvement of p75 neurotrophin receptor (p75NTR) in Abeta-treated human neurons. We find that Abeta1-40 and Abeta1-42, but not the reverse control peptide, Abeta40-1, rapidly increase the levels of p75NTR in a specific and dose-dependent manner. In contrast to observations in cell lines, enhanced expression of p75NTR in human neurons via a herpes simplex virus amplicon vector does not increase the susceptibility of neurons to Abeta. Unexpectedly, inhibition of p75NTR expression with an antisense expression construct or incubation of the cells with an antibody to the extracellular domain of p75NTR sensitizes human neurons to extracellular nonfibrillar or fibrillar Abeta1-42 cytotoxicity. Unlike intracellular Abeta, extracellular Abeta toxicity is independent of p53 and Bax activity. However, Abeta toxicity is inhibited by caspase inhibitors and the glycogen synthase kinase 3beta inhibitor lithium. Neuroprotection against Abeta is phosphatidylinositide 3-kinase dependent but Akt independent. These results are consistent with a neuroprotective role for p75NTR against extracellular Abeta toxicity in human neurons.
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124
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Shonukan O, Bagayogo I, McCrea P, Chao M, Hempstead B. Neurotrophin-induced melanoma cell migration is mediated through the actin-bundling protein fascin. Oncogene 2003; 22:3616-23. [PMID: 12789270 DOI: 10.1038/sj.onc.1206561] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Expression of the p75 neurotrophin receptor (p75(NTR)) in primary melanomas is associated with deeply invasive lesions. In turn, there is expression of high levels of neurotrophins at the invasion front of normal tissue adjacent to brain metastases, thus implicating this growth factor-receptor system in melanoma tumorigenesis. The neurotrophins nerve growth factor (NGF) and neurotrophin-3 (NT-3) are potent chemotactic agents for human melanoma cells which express p75(NTR)in vitro. Here we show that the actin-bundling protein fascin specifically interacts with p75(NTR) in an NGF-dependent manner by co-immunoprecipitation and colocalization in melanoma cells that express the two proteins endogenously. In addition, expression of a fascin point mutant at the serine phosphorylation site (serine 39) regulating actin binding abrogates neurotrophin-induced migration. These results suggest a causal role for NGF-mediated dephosphorylation of serine 39 on fascin in mediating actin binding and subsequent melanoma cell migration.
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Affiliation(s)
- Oluwatoyin Shonukan
- Department of Medicine, Division of Hematology/Oncology, University of Miami School of Medicine, Miami, FL 33136, USA.
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125
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Higuchi H, Yamashita T, Yoshikawa H, Tohyama M. PKA phosphorylates the p75 receptor and regulates its localization to lipid rafts. EMBO J 2003; 22:1790-800. [PMID: 12682012 PMCID: PMC154469 DOI: 10.1093/emboj/cdg177] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although a large number of studies have been carried out on the diverse effects mediated by the common neurotrophin receptor p75(NTR), little is known about the molecular mechanisms by which p75(NTR) initiates intracellular signal transduction. We identified a variant of the beta catalytic subunit of cAMP-dependent protein kinase (PKACbeta) as a p75(NTR)-interacting protein, which phosphorylates p75(NTR) at Ser304. Intracellular cAMP in cerebellar neurons was accumulated transiently by ligand binding to p75(NTR). Activation of cAMP-PKA is required for translocation of p75(NTR) to lipid rafts, and for biochemical and biological activities of p75(NTR), such as inactivation of Rho and the neurite outgrowth. Proper recruitment of activated p75(NTR) to lipid rafts, structures that represent specialized signaling organelles, is of fundamental importance in determining p75(NTR) bioactivity.
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Affiliation(s)
- Haruhisa Higuchi
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-087, Japan
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126
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Pappas TC, Decorti F, Macdonald NJ, Neet KE, Taglialatela G. Tumour necrosis factor-alpha- vs. growth factor deprivation-promoted cell death: different receptor requirements for mediating nerve growth factor-promoted rescue. Aging Cell 2003; 2:83-92. [PMID: 12882321 DOI: 10.1046/j.1474-9728.2003.00039.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Physiological and pathological aging of the central nervous system (CNS) is characterized by functional neuronal impairments which may lead to perturbed cell homeostasis and eventually to neuronal death. Many toxic events may underlie age-related neurodegeneration. These include the effects of beta amyloid, Tau and mutated presenilin proteins, free radicals and oxidative stress, pro-inflammatory cytokines and lack of growth factor support, which can be individually or collectively involved. Taken individually, these toxicants can induce very diverse cell responses, thus requiring individually targeted corrective interventions upstream of common cell death (apoptotic) pathways. Recent preliminary evidence suggests that the pro-inflammatory cytokine tumour necrosis factor alpha (TNFalpha) and growth factor withdrawal can both activate a common apoptotic pathway in nerve growth factor (NGF)-responsive PC12 cells involving caspase 3, albeit through very distinct upstream pathways: the former through active signalling and the latter through passive or lack of survival signalling. Here, we show that NGF can rescue PC12 cells from both growth factor withdrawal- and TNFalpha-promoted cell death. However, NGF rescue from growth factor withdrawal requires NGF signalling through the high-affinity tyrosine kinase receptor (TrkA), while NGF rescue from TNFalpha-promoted cell death requires NGF signalling through the low-affinity p75NTR receptor. These results strengthen the idea that prevention of age- or pathology-associated neurodegeneration may require varied molecular approaches reflecting the diversity of the toxicants involved, possibly acting simultaneously.
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Affiliation(s)
- Todd C Pappas
- Center for Biomedical Engineering, The University of Texas Medical Branch at Galveston, Galveston, TX 77555 -1043, USA
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127
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Viani P, Giussani P, Brioschi L, Bassi R, Anelli V, Tettamanti G, Riboni L. Ceramide in nitric oxide inhibition of glioma cell growth. Evidence for the involvement of ceramide traffic. J Biol Chem 2003; 278:9592-601. [PMID: 12515829 DOI: 10.1074/jbc.m207729200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The treatment of C6 glioma cells with the nitric oxide donor, PAPANONOate ((Z)-[N-(3-ammoniopropyl)-N-(n-propyl)amino]diazen-1-ium-1,2-diolate), resulted in a dose-dependent inhibition of cell proliferation. This was associated to a rapid and significant increase of ceramide levels and was mimicked by treatments that augment cellular ceramide. Metabolic experiments with radioactive sphingosine, serine, and choline showed that nitric oxide strongly reduced the utilization of ceramide for the biosynthesis of both sphingomyelin and glucosylceramide. Nevertheless, nitric oxide did not modify the activity of different enzymes of ceramide metabolism. The possibility that nitric oxide impairs the availability of ceramide for sphingolipid biosynthesis was then investigated. The metabolism of N-hexanoyl-[(3)H]sphingosine demonstrated that nitric oxide did not affect the biosynthesis of N-hexanoyl-[(3)H]sphingolipids but inhibited the metabolic utilization of long chain [(3)H]ceramide, synthesized in the endoplasmic reticulum (ER) from the recycled [(3)H]sphingosine. Moreover, results obtained with fluorescent ceramides, brefeldin A, ATP depletion, as well as in a ceramide transport assay indicate that nitric oxide impairs the traffic of ceramide from ER to Golgi apparatus. All this supports that, in glioma cells, the modulation of ceramide traffic can contribute to the regulation of its intracellular levels and participate in the nitric oxide-activated signaling pathway involved in the control of cell proliferation.
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Affiliation(s)
- Paola Viani
- Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, via Fratelli Cervi 93, Segrate, Milan 20090, Italy.
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128
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Culmsee C, Gerling N, Lehmann M, Nikolova-Karakashian M, Prehn JHM, Mattson MP, Krieglstein J. Nerve growth factor survival signaling in cultured hippocampal neurons is mediated through TrkA and requires the common neurotrophin receptor P75. Neuroscience 2003; 115:1089-108. [PMID: 12453482 DOI: 10.1016/s0306-4522(02)00539-0] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The role of the common neurotrophin receptor p75 (p75NTR) in neuronal survival and cell death remains controversial. On the one hand, p75NTR provides a positive modulatory influence on nerve growth factor (NGF) signaling through the high affinity neurotrophin receptor TrkA, and hence increases NGF survival signaling. However, p75NTR may also signal independently of TrkA, causing cell death or cell survival, depending on the cell type and stage of development. Here we demonstrate that TrkA is expressed in primary cultures of hippocampal neurons and is activated by NGF within 10 min of exposure. In primary hippocampal cultures neuroprotection by NGF against glutamate toxicity was mediated by NF-kappaB and accompanied by an increased expression of neuroprotective NF-kappaB target genes Bcl-2 and Bcl-xl. In mouse hippocampal cells lacking p75NTR (p75NTR-/-) activation of TrkA by NGF was not detectable. Moreover, neuroprotection by NGF against glutamate toxicity was abolished in p75NTR-/- neurons, and the expression of bcl-2 and bcl-xl was markedly reduced as compared to wildtype cells. NGF increased TrkA phosphorylation in hippocampal neurons and provided protection that required phosphoinositol-3-phosphate (PI3)-kinase activity and Akt phosphorylation, whereas the mitogen-activated protein kinases (MAPK), extracellular-regulated kinases (Erk) 1/2, were not involved. P75NTR signaling independent of TrkA, such as increased neutral sphingomyelinase (NSMase) activity causing enhanced levels of ceramide, were not detected after exposure of hippocampal neurons to NGF. Interestingly, inhibition of sphingosine-kinase blocked the neuroprotective effect of NGF, suggesting that sphingosine-1-phosphate was also involved in NGF-mediated survival in our cultured hippocampal neurons. Overall, our results indicate an essential role for p75NTR in supporting NGF-triggered TrkA signaling pathways mediating neuronal survival in hippocampal neurons.
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MESH Headings
- Animals
- Brain-Derived Neurotrophic Factor/pharmacology
- Cell Survival/drug effects
- Cell Survival/genetics
- Excitatory Amino Acid Agonists/pharmacology
- Female
- Hippocampus/drug effects
- Hippocampus/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- NF-kappa B/drug effects
- NF-kappa B/metabolism
- Nerve Growth Factor/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Neuroprotective Agents/metabolism
- Neuroprotective Agents/pharmacology
- PC12 Cells
- Phosphatidylinositol 3-Kinases/drug effects
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphotransferases (Alcohol Group Acceptor)/antagonists & inhibitors
- Phosphotransferases (Alcohol Group Acceptor)/metabolism
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins/drug effects
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Nerve Growth Factor
- Receptor, trkA/drug effects
- Receptor, trkA/genetics
- Receptor, trkA/metabolism
- Receptors, Nerve Growth Factor/deficiency
- Receptors, Nerve Growth Factor/genetics
- Signal Transduction/drug effects
- Signal Transduction/genetics
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Affiliation(s)
- C Culmsee
- Institut für Pharmakologie und Toxikologie, Philipps-Universität Marburg, Ketzerbach 63, 35032, Marburg, Germany.
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129
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Ito M. Insulin or bFGF and C2 ceramide increase newborn rat retinal ganglion cell survival rate. Biochem Biophys Res Commun 2003; 301:564-71. [PMID: 12565900 DOI: 10.1016/s0006-291x(03)00012-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Treatment of RGCs with insulin or C2 ceramide alone increased survival rate by 30%. Adding both insulin and C2 ceramide increased survival rate by 80%. Protein phosphatase 2A (PP2A) inhibitor okadaic acid (OA) eliminated the effect of C2 ceramide, but not that of insulin. Protein kinase inhibitor K252a decreased the effect of C2 ceramide in a dose-dependent manner, but the effect of insulin was not changed. Treatment of RGCs with bFGF increased survival rate by 36%. Adding both bFGF and C2 ceramide increased survival rate by 102%. OA did not alter the effect of bFGF, whereas K252a increased survival rate in a dose-dependent manner. Inhibition of C2 ceramide by OA suggests that PP2A activation is involved in its pathway, whereas PP2A is not involved in the insulin- and bFGF-activated pathway. Elimination of the effect of C2 ceramide by K252a suggests that sphingomyelin cycle activation is mediated by a protein kinase not important in the insulin-activated pathway. Moreover, the increased effect of bFGF and dose-dependently decreased effect of C2 ceramide by K252a suggest that different protein kinases are important in bFGF- and ceramide-mediated enhancement of RGC survival rate.
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Affiliation(s)
- Mami Ito
- Department of Ophthalmology, Hiroshima University, School of Medicine, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
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130
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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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131
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Apfel SC. Nerve growth factor for the treatment of diabetic neuropathy: what went wrong, what went right, and what does the future hold? INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 50:393-413. [PMID: 12198818 DOI: 10.1016/s0074-7742(02)50083-0] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Since their discovery in the 1950s, neurotrophic factors have raised expectations that their clinical application to neurodegenerative diseases might provide an effective therapy for what are now untreatable conditions. Nerve growth factor (NGF) was the first neurotrophic factor to be discovered and was one of the earliest to proceed to clinical trials. NGF, which is selectively trophic for small fiber sensory and sympathetic neurons, was selected as a potential theraphy for diabetic polyneuropathy becaus of the serious consequences associated with degeneration of those neuronal populations in this condition. In addition, evidence shows that reduced availability of NGF may contribute to the pathogenesis of diabetic neuropathy, and animal models of neuropathy respond to the exogenous administration of NGF. Two sets of phase II clinical trails suggested that recombinant human NGF (rhNGF) administration was effective at ameliorating the symptoms associated with both diabetic polyneuropathy and HIV-related neuropathy. These early studies, however, revealed that painful side effects were dose limiting for NGF. A large-scale phase III clinical trail of 1019 patients randomized to receive either rhNGF or palcebo for 48 weeks failed to confirm the earlier indications of efficacy. Among the explanations offered for the discrepancy between the two sets of trails was a robust palcebo effect, inadequate dosage, different study populatioms, and changes to the formulation of rhNGF for the phase III trail. As a result of the phase III outcome, Genentech has decided not to proceed with further development of rhNGF.
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Affiliation(s)
- Stuart C Apfel
- Albert Einstein College of Medicine, Bronx, New York 10461, USA
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132
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van Blitterswijk WJ, van der Luit AH, Veldman RJ, Verheij M, Borst J. Ceramide: second messenger or modulator of membrane structure and dynamics? Biochem J 2003; 369:199-211. [PMID: 12408751 PMCID: PMC1223095 DOI: 10.1042/bj20021528] [Citation(s) in RCA: 335] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Revised: 10/30/2002] [Accepted: 10/31/2002] [Indexed: 12/18/2022]
Abstract
The physiological role of ceramide formation in response to cell stimulation remains controversial. Here, we emphasize that ceramide is not a priori an apoptotic signalling molecule. Recent work points out that the conversion of sphingomyelin into ceramide can play a membrane structural (physical) role, with consequences for membrane microdomain function, membrane vesiculation, fusion/fission and vesicular trafficking. These processes contribute to cellular signalling. At the Golgi, ceramide takes part in a metabolic flux towards sphingomyelin, diacylglycerol and glycosphingolipids, which drives lipid raft formation and vesicular transport towards the plasma membrane. At the cell surface, receptor clustering in lipid rafts and the formation of endosomes can be facilitated by transient ceramide formation. Also, signalling towards mitochondria may involve glycosphingolipid-containing vesicles. Ceramide may affect the permeability of the mitochondrial outer membrane and the release of cytochrome c. In the effector phase of apoptosis, the breakdown of plasma membrane sphingomyelin to ceramide is a consequence of lipid scrambling, and may regulate apoptotic body formation. Thus ceramide formation serves many different functions at distinct locations in the cell. Given the limited capacity for spontaneous intracellular diffusion or membrane flip-flop of natural ceramide species, the topology and membrane sidedness of ceramide generation are crucial determinants of its impact on cell biology.
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Affiliation(s)
- Wim J van Blitterswijk
- Division of Cellular Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
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133
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Lachyankar MB, Condon PJ, Daou MC, De AK, Levine JB, Obermeier A, Ross AH. Novel functional interactions between Trk kinase and p75 neurotrophin receptor in neuroblastoma cells. J Neurosci Res 2003; 71:157-72. [PMID: 12503079 DOI: 10.1002/jnr.10480] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To understand the functional interactions between the TrkA and p75 nerve growth factor (NGF) receptors, we stably transfected LAN5 neuroblastoma cells with an expression vector for ET-R, a chimeric receptor with the extracellular domain of the epidermal growth factor receptor (EGFR), and the TrkA transmembrane and intracellular domains. EGF activated the ET-R kinase and induced partial differentiation. NGF, which can bind to endogenous p75, did not induce differentiation but enhanced the EGF-induced response, leading to differentiation of almost all cells. A mutated NGF, 3T-NGF, that binds to TrkA but not to p75 did not synergize with EGF. Enhancement of EGF-induced differentiation required at least nanomolar concentrations of NGF, consistent with the low-affinity p75 binding site. EGF may induce a limited number of neuronal cells because it also enhanced apoptosis. Both NGF and a caspase inhibitor reduced apoptosis and, thereby, enhanced differentiation. NGF seems to enhance survival through the phosphatidylinositol-3 kinase (PI3K) pathway. Consistent with this hypothesis, Akt, a downstream effector of the PI3K pathway, was hyperphosphorylated in the presence of EGF+NGF. These results demonstrate that TrkA kinase initiates differentiation, and p75 enhances differentiation by rescuing differentiating cells from apoptosis via the PI3K pathway. Even though both EGF and NGF are required for differentiation of LAN5/ET-R cells, only NGF is required for survival of the differentiated cells. In the absence of NGF, the cells die by an apoptotic mechanism, involving caspase-3. An anti-p75 antibody blocked the survival effect of NGF. Brain-derived neurotrophic factor also enhanced cell survival, indicating that in differentiated cells, NGF acts through the p75 receptor to prevent apoptosis.
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Affiliation(s)
- Mahesh B Lachyankar
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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134
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Marchetti D, Denkins Y, Reiland J, Greiter-Wilke A, Galjour J, Murry B, Blust J, Roy M. Brain-metastatic melanoma: a neurotrophic perspective. Pathol Oncol Res 2003; 9:147-58. [PMID: 14530807 DOI: 10.1007/bf03033729] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2003] [Accepted: 09/13/2003] [Indexed: 12/24/2022]
Abstract
The brain is a unique microenvironment enclosed by the skull and maintaining a highly regulated vascular transport barrier. To metastasize to the brain, malignant tumor cells must attach to microvessel endothelial cells, invade the blood-brain barrier (BBB), and respond to brain survival and growth factors. Neurotrophins (NT) are important in brain invasion because they stimulate this process. In brain-metastatic melanoma cells, NT can promote invasion by enhancing the production of extracellular matrixdegradative enzymes such as heparanase, an enzyme capable of locally destroying both the extracellular matrix and the basement membrane of the BBB. We have examined human and murine melanoma cell lines exhibiting varying abilities to form brain metastases, and have found that they express low-affinity neurotrophin receptor p75NTR in relation to their brain-metastatic potentials. They do not, however, express trkA, the gene encoding the tyrosine kinase receptor TrkA, the high-affinity receptor for nerve growth factor (NGF), the prototypic NT. Presence of functional TrkC, the putative receptor for the invasion-promoting neurotrophin NT-3, was also expressed in these cells. Brain-metastatic melanoma cells can also produce autocrine factors and inhibitors that influence their growth, invasion, and survival in the brain. Synthesis of these factors may influence NT production by brain cells adjacent to the neoplastic invasion front, such as oligodendrocytes and astrocytes. In brain biopsies, we observed increased amounts of NGF and NT-3 in tumor-adjacent tissues at the invasion front of human melanoma tumors. Additionally, we found that astrocytes contribute to the brain-metastatic specificity of melanoma cells by producing NT-regulated heparanase. Trophic, autocrine, and paracrine growth factors may therefore determine whether metastatic cells can successfully invade, colonize, and grow in the central nervous system (CNS).
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Affiliation(s)
- Dario Marchetti
- Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803, USA.
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135
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Inverse Genomics as a powerful tool to identify novel targets for the treatment of neurodegenerative diseases. Mech Ageing Dev 2003; 124:125-32. [PMID: 12618015 DOI: 10.1016/s0047-6374(02)00175-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Toward the prevention of neurodegeneration we have used Immusol's Inverse Genomics platform to identify gene targets involved in neuronal cell death. Inverse genomics uses a combinatorial library of unique hairpin ribozymes with randomized substrate binding sequences to cleave unique RNA transcripts, thereby decreasing translation of the encoded proteins. Using the SK-N-MC neuroblastoma cell line a cell based survival selection assay was designed with C2-ceramide or TNFalpha as an induction signal for apoptosis. SK-N-MC cells were stably transduced with a ribozyme vector library, and then exposed to 20 microM C2-ceramide or 50 ng/ml TNFalpha to induce cell death. Surviving cells were harvested, their DNA isolated, and the ribozymes rescued by PCR for re-introduction into fresh cells. After several rounds of selection and ribozyme rescue we have identified individual ribozymes that protect neuronal cells from C2-ceramide induced apoptosis. Three of the cellular targets of these ribozyme sequence tags have been validated. Microarray analysis and yeast two-hybrid screens have also been used to gain insight into the pathways involved by identifying additional players involved in these pathways. These target genes may also serve as therapeutic targets for development of drugs for Alzheimer and Parkinson's diseases.
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136
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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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137
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Shin CY, Lee YP, Lee TS, Song HJ, Sohn UD. C(2)-ceramide-induced circular smooth muscle cell contraction involves PKC-epsilon and p44/p42 MAPK activation in cat oesophagus. Mitogen-activated protein kinase. Cell Signal 2002; 14:925-32. [PMID: 12220618 DOI: 10.1016/s0898-6568(02)00038-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We investigated the mechanism of C(2)-ceramide (C(2))-induced circular smooth muscle cell contraction in cat oesophagus. C(2) produced contraction of smooth muscle cells isolated by enzymatic digestion, peaked at 30 s and was sustained at a plateau at 5 min. The response to C(2) was concentration-dependent. H-7 or chelerythrine inhibited C(2)-induced contraction, while the diacylglycerol (DAG) kinase inhibitor, R59949, had no effect, suggesting that the contraction is protein kinase C (PKC) pathway-dependent. To test if PKC-mediated contraction may be isozyme-specific, we examined the effects of PKC isozymes antibodies on contraction. PKC-epsilon antibody inhibited the contraction by C(2) but not by PKC-betaII or -gamma, suggesting that PKC-epsilon mediates the contraction by C(2). To characterize the specific PKC isozymes that mediate contraction of the smooth muscle cells, we used, as an inhibitor, N-myristoylated peptides (myr-PKC) derived from the pseudosubstrate sequences of PKC-(alpha)(beta)(gamma), -alpha, -delta, or -epsilon. myr-PKC-epsilon only inhibited the contraction, which was concentration-dependent, suggesting that PKC-epsilon isozyme is involved in the contraction. To examine which mitogen-activated protein kinases (MAPKs) are involved in C(2)-induced contraction, specific MAPK inhibitors (MEK inhibitor, PD98059, and p38 MAPK inhibitor, SB202190) are used. Preincubation of PD98059 blocked the contraction induced by C(2) in a concentration-dependent manner. However, SB202190 had no effects on contraction. C(2) increased the intensity of the bands identified by phosphospecific p44/p42 MAPK antibody and preincubation of PD98059 decreased the intensity of bands as compared with C(2)-stimulated cells. In conclusion, C(2) produced the contraction of smooth muscle cells of cat oesophagus. The contraction is mediated by PKC-epsilon, resulting in the activation of p44/p42 MAPK.
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Affiliation(s)
- Chang Yell Shin
- Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul, South Korea
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138
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Zhang DX, Yi FX, Zou AP, Li PL. Role of ceramide in TNF-alpha-induced impairment of endothelium-dependent vasorelaxation in coronary arteries. Am J Physiol Heart Circ Physiol 2002; 283:H1785-94. [PMID: 12384455 DOI: 10.1152/ajpheart.00318.2002] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study tested the hypothesis that ceramide, a sphingomylinase metabolite, serves as an second messenger for tumor necrosis factor-alpha (TNF-alpha) to stimulate superoxide production, thereby decreasing endothelium-dependent vasorelaxation in coronary arteries. In isolated bovine small coronary arteries, TNF-alpha (1 ng/ml) markedly attenuated vasodilator responses to bradykinin and A-23187. In the presence of N(G)-nitro-L-arginine methyl ester, TNF-alpha produced no further inhibition on the vasorelaxation induced by these vasodilators. With the use of 4,5-diaminofluorescein diacetate fluorescence imaging analysis, bradykinin was found to increase nitric oxide (NO) concentrations in the endothelium of isolated bovine small coronary arteries, which was inhibited by TNF-alpha. Pretreatment of the arteries with desipramine (10 microM), an inhibitor of acidic sphingomyelinase, tiron (1 mM), a superoxide scavenger, and polyethylene glycol-superoxide dismutase (100 U/ml) largely restored the inhibitory effect of TNF-alpha on bradykinin- and A-23187-induced vasorelaxation. In addition, TNF-alpha activated acidic sphingomyelinase and increased ceramide levels in coronary endothelial cells. We conclude that TNF-alpha inhibits NO-mediated endothelium-dependent vasorelaxation in small coronary arteries via sphingomyelinase activation and consequent superoxide production in endothelial cells.
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Affiliation(s)
- David X Zhang
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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139
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Zhang YH, Vasko MR, Nicol GD. Ceramide, a putative second messenger for nerve growth factor, modulates the TTX-resistant Na(+) current and delayed rectifier K(+) current in rat sensory neurons. J Physiol 2002; 544:385-402. [PMID: 12381813 PMCID: PMC2290585 DOI: 10.1113/jphysiol.2002.024265] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Because nerve growth factor (NGF) is elevated during inflammation and is known to activate the sphingomyelin signalling pathway, we examined whether NGF and its putative second messenger, ceramide, could modulate the excitability of capsaicin-sensitive adult and embryonic sensory neurons. Using the whole-cell patch-clamp recording technique, exposure of isolated sensory neurons to either 100 ng ml(-1) NGF or 1 microM N-acetyl sphingosine (C2-ceramide) produced a 3- to 4-fold increase in the number of action potentials (APs) evoked by a ramp of depolarizing current in a time-dependent manner. Intracellular perfusion with bacterial sphingomyelinase (SMase) also increased the number of APs suggesting that the release of native ceramide enhanced neuronal excitability. Glutathione, an inhibitor of neutral SMase, completely blocked the NGF-induced augmentation of AP firing, whereas dithiothreitol, an inhibitor of acidic SMase, was without effect. In the presence of glutathione and NGF, exogenous ceramide still enhanced the number of evoked APs, indicating that the sensitizing action of ceramide was downstream of NGF. To investigate the mechanisms of action for NGF and ceramide, isolated membrane currents were examined. Both NGF and ceramide facilitated the peak amplitude of the TTX-resistant sodium current (TTX-R I(Na)) by approximately 1.5-fold and shifted the activation to more hyperpolarized voltages. In addition, NGF and ceramide suppressed an outward potassium current (I(K)) by approximately 35 %. Ceramide reduced I(K) in a concentration-dependent manner. Isolation of the NGF- and ceramide-sensitive currents indicates that they were delayed rectifier types of I(K). The inflammatory prostaglandin, PGE(2), produced an additional suppression of I(K) after exposure to ceramide (approximately 35 %), suggesting that these agents might act on different targets. Thus, our findings indicate that the pro-inflammatory agent, NGF, can rapidly enhance the excitability of sensory neurons. This NGF-induced sensitization is probably mediated by activation of the sphingomyelin signalling pathway to liberate ceramide(s), wherein ceramide appears to be the second messenger involved in modulating neuronal excitability.
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Affiliation(s)
- Y H Zhang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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140
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Paratcha G, Ibáñez CF. Lipid rafts and the control of neurotrophic factor signaling in the nervous system: variations on a theme. Curr Opin Neurobiol 2002; 12:542-9. [PMID: 12367633 DOI: 10.1016/s0959-4388(02)00363-x] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Lipid rafts are specialized, liquid-ordered subdomains of the plasma membrane. Through their ability to promote specific compartmentalization of lipids and membrane proteins, lipid rafts have emerged as membrane platforms specialized for signal transduction. In recent years, signaling by neurotrophic factors and their receptors has been shown to depend upon the integrity and function of lipid rafts and associated components. It has also been shown that these microdomains play critical roles in selective axon-dendritic sorting and the proteolytic processing of several neurotrophic ligands and receptors in neuronal cells. The available evidence supports an important role for lipid rafts in the initiation, propagation and maintenance of signal transduction events triggered by different neurotrophic factors and their receptors in the nervous system.
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Affiliation(s)
- Gustavo Paratcha
- Division of Molecular Neurobiology, Department of Neuroscience, Karolinska Institute, Retzius väg 8, A2:2, Stockholm, Sweden.
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141
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Ito H, Nomoto H, Furukawa S. Role of low-affinity p75 receptor in nerve growth factor-inducible growth arrest of PC12 cells. J Neurosci Res 2002; 69:653-61. [PMID: 12210831 DOI: 10.1002/jnr.10359] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mutant PC12 cell clones (PC84 cells) were obtained by transfection with nerve growth factor (NGF) cDNA. These cells secreted active NGF, extended short processes, and proliferated faster than the parental PC12 cells. These features are of great interest because the parental PC12 cells cease proliferation and extend long processes when transfected with NGF cDNA. PC84 cells expressed a high level of acetylcholinesterase activity and neurofilament M, which indicates that PC84 cells were differentiated. The inhibition of TrkA by K252a diminished the short processes of PC84 cells but had no effect on their fast proliferation. The expression level of TrkA in PC84 cells was comparable to that in PC12 cells; whereas that of another NGF receptor, p75, was significantly lower. These data suggest that the decrease of p75 contributed to the continuous growth of PC84 cells, which was confirmed by suppressing p75 activity of PC12 cells with the antisense oligonucleotide of p75 or with anti-p75 neutralizing antibody. The treated cells did not cease proliferation in the presence of NGF and extended short processes. Our results suggest that NGF signaling via TrkA affects the differentiation characteristics of PC12 cells but that an additional signaling via p75 is necessary for the growth arrest of the cells.
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MESH Headings
- Acetylcholinesterase/drug effects
- Acetylcholinesterase/metabolism
- Animals
- Blotting, Western
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Division/drug effects
- Cell Division/physiology
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Neoplastic
- Mutation
- Nerve Growth Factor/genetics
- Nerve Growth Factor/metabolism
- Nerve Growth Factor/pharmacology
- Oligoribonucleotides, Antisense/pharmacology
- PC12 Cells/drug effects
- PC12 Cells/metabolism
- Rats
- Receptor, Nerve Growth Factor/genetics
- Receptor, Nerve Growth Factor/physiology
- Receptor, trkA/genetics
- Receptor, trkA/physiology
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Tumor Cells, Cultured/drug effects
- Tumor Cells, Cultured/metabolism
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Affiliation(s)
- Hisanori Ito
- Laboratory of Molecular Biology, Gifu Pharmaceutical University, Gifu, Japan
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142
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Fraley GS, Ulibarri C. Development of androgen receptor and p75(NTR) mRNAs and peptides in the lumbar spinal cord of the gerbil. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 137:101-14. [PMID: 12220702 DOI: 10.1016/s0165-3806(02)00412-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Development of sex differences in the spinal cord appears to be largely under the control of androgen and although neurotrophins may also have a role. Spinal cords of male and female neonatal gerbils (postnatal days 1, 5, 7, 10, 23) and adult gerbils (postnatal day 150) were examined to determine the relative temporal expression of androgen receptor (AR) and the low-affinity neurotrophin receptor (p75) mRNAs within the spinal nucleus of the bulbocavernosus (SNB) and dorsolateral nucleus (DLN). Furthermore, prepubertal male gerbils were placed into one of six gonadal hormone treatment groups at weaning: Either sham castrate, castrated with gonadal hormone replacement, or castrated without gonadal hormone replacement. Ten weeks later gerbils were aldehyde-perfused, spinal cords removed and processed for presence of AR and p75 immunoreactivity (ir) in motoneurons of the SNB and DLN. During neonatal development, there were significant increases in androgen receptor mRNA within the SNB and DLN. In the SNB, the increase in androgen receptor mRNA preceded the increase in p75 mRNA. Peripubertally, significantly more SNB than DLN motoneurons contained AR- and p75-ir. These data demonstrate that AR expression occurs along the same developmental time frame as the development of the SNB and DLN and the organizational effects of androgens on their development continues through puberty in the male gerbil.
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MESH Headings
- Aging/metabolism
- Animals
- Animals, Newborn
- Cell Differentiation/drug effects
- Cell Differentiation/genetics
- Estradiol/metabolism
- Female
- Gerbillinae
- Immunohistochemistry
- Male
- Motor Neurons/cytology
- Motor Neurons/drug effects
- Motor Neurons/metabolism
- Peptides/genetics
- Peptides/metabolism
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptor, Nerve Growth Factor
- Receptors, Androgen/drug effects
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Nerve Growth Factor/drug effects
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/metabolism
- Sex Characteristics
- Sex Differentiation/drug effects
- Sex Differentiation/genetics
- Spinal Cord/cytology
- Spinal Cord/growth & development
- Spinal Cord/metabolism
- Testosterone/metabolism
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Affiliation(s)
- Gregory Scott Fraley
- Program in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99161-6520 USA.
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143
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Riboni L, Campanella R, Bassi R, Villani R, Gaini SM, Martinelli-Boneschi F, Viani P, Tettamanti G. Ceramide levels are inversely associated with malignant progression of human glial tumors. Glia 2002; 39:105-13. [PMID: 12112362 DOI: 10.1002/glia.10087] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Ceramide represents an important sphingoid mediator involved in the signaling pathways that control cell proliferation, differentiation, and death. To determine whether ceramide levels correlate with the malignant progression of human astrocytomas, we investigated these levels in surgical specimens of glial tumors of low-grade and high-grade malignancy. Tumor samples obtained from 52 patients who underwent therapeutic removal of primary brain tumors were used. The tumors were classified according to standard morphologic criteria and were grouped into tumors of low-grade and high-grade malignancy. Sections of normal brain tissue adjacent to the tumor were also analyzed in 11 of the 52 patients. After extraction and partial purification, ceramide was measured by quantitative derivatization to ceramide-1-phosphate using diacylglycerol kinase and [gamma-(32)P]ATP. Ceramide levels were significantly lower in the combined high-grade tumors compared with low-grade tumors and in both tumor groups compared with peritumoral tissue. The results indicate an inverse correlation between the amount of ceramide and tumor malignancy as assessed by both the histological grading and ganglioside pattern. Moreover, overall survival analysis of 38 patients indicates that ceramide levels are significantly associated with patient survival. The present findings indicate that ceramide is inversely associated with malignant progression of human astrocytomas and poor prognosis. The downregulation of ceramide levels in human astrocytomas emerges as a novel alteration that may contribute to glial neoplastic transformation. The low ceramide levels in high-grade tumors may provide an advantage for their rapid growth and apoptotic resistant features. This study appears to support the rationale for the potential benefits of a ceramide-based chemotherapy.
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Affiliation(s)
- Laura Riboni
- Department of Medical Chemistry and Biochemistry, Study Center for the Functional Biochemistry of Brain Lipids, University of Milan, LITA-Segrate, Segrate, Milan, Italy.
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144
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Luberto C, Kraveka JM, Hannun YA. Ceramide regulation of apoptosis versus differentiation: a walk on a fine line. Lessons from neurobiology. Neurochem Res 2002; 27:609-17. [PMID: 12374196 DOI: 10.1023/a:1020267831851] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
One of the characteristics of ceramide-mediated biology is the variety of biological outcomes observed in response to its intracellular accumulation. The molecular mechanisms that govern the cell "decision-making" in response to ceramide remain largely unclear. In this perspective, the study of neural models has begun to provide important insight into the understanding of these mechanisms that regulate differentiation and cell death. Indeed, differentiation and cell death are among the most common effects elicited by ceramide in most cell types and in neural cells, too. Therefore, the lessons we may learn from the study of ceramide regulation of neurobiology would also shed light on the regulation of ceramide-mediated biology in other cellular models. Since increasing evidence links aberrant metabolism of ceramide to different pathologies, the understanding of the mechanisms underlying these events may represent the key to the design of novel therapeutic approaches.
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Affiliation(s)
- Chiara Luberto
- Department of Biochemistry, Medical University of South Carolina, Charleston 29425, USA
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145
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Affiliation(s)
- Caroline Olgart Höglund
- Institut National de la Santé et de la Recherche Médicale Unité 425, Neuroimmunopharmacologie pulmonaire, Faculté de Pharmacie, Université Louis Pasteur Strasbourg - I, B.P. 24, 67 401 Illkirch Cedex, France.
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146
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Kishibe K, Yamada Y, Ogawa K. Production of nerve growth factor by mouse hepatocellular carcinoma cells and expression of TrkA in tumor-associated arteries in mice. Gastroenterology 2002; 122:1978-86. [PMID: 12055603 DOI: 10.1053/gast.2002.33581] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND & AIMS Nerve growth factor (NGF) has been suggested to play a role in cancer progression. We found that NGF is specifically elevated in mouse hepatocellular carcinomas (HCCs) by cDNA array analysis. The present study aimed to elucidate expression of NGF and its receptors during hepatocarcinogenesis and under other conditions. METHODS Expression of NGF, TrkA, and p75NTR was investigated in HCCs developing and regenerating livers, and primary hepatocyte cultures in B6C3F(1) mice by reverse-transcription polymerase chain reaction, Northern blotting, and/or immunohistochemistry. The biological activity of NGF produced by the HCC cells was studied by using PC12 cells. Nerve fibers in hepatic tumors were immunohistochemically examined. RESULTS Although NGF was negative in adult and developing livers, it was markedly elevated in focal hepatocytic lesions from early stages of carcinogenesis. Appreciable levels were also detected in regenerating livers and hepatocytes in culture. The conditioned medium of HCC cells caused PC12 neurite outgrowth, but this was reduced on pretreatment of the conditioned medium with an anti-NGF antibody or NGF antisense expression in HCC cells. Although neither TrkA nor p75NTR was detectable in either HCC or normal hepatic cells, TrkA was shown in the walls of tumor-associated arteries that contain abundant nerve fibers. CONCLUSIONS NGF is expressed by hepatocytes during carcinogenesis, regeneration, and primary culture but may have cells other than hepatocytes as the target. TrkA expression and the abundance of nerve fibers in the walls of tumor-associated arteries suggest a possible role for NGF in angiogenesis.
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Affiliation(s)
- Kan Kishibe
- Department of Pathology, Asahikawa Medical College, Midorigaoka, Japan
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147
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Cupp AS, Tessarollo L, Skinner MK. Testis developmental phenotypes in neurotropin receptor trkA and trkC null mutations: role in formation of seminiferous cords and germ cell survival. Biol Reprod 2002; 66:1838-45. [PMID: 12021070 DOI: 10.1095/biolreprod66.6.1838] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The objective of the present study was to determine if the neurotropin receptors trkC and trkA are involved in embryonic testis development. These receptors bind neurotropin 3 and nerve growth factor, respectively. The hypothesis tested was that the absence of trkC or trkA receptors will have detrimental effects on testis development and morphology. The trkA and trkC homozygote knockout (KO) mice generally die either at or shortly after birth. Therefore, heterozygote mice were mated to obtain homozygote gene KO mice at Embryonic Day (E) 13, E14, E17, and E19 of gestation, with E0 being the plug date. Gonads from approximately 80 embryos were collected and fixed, and each embryo was genotyped. To determine gonadal characteristics for each genotype, the number of germ cells, number of seminiferous cords, seminiferous cord area, and interstitial area were calculated at each developmental age. Germ cell numbers varied in trkA gene KO mice from those of wild-type mice at each age evaluated. In trkC gene KO mice, differences were detected in germ cell numbers when compared to wild-type mice at E17 and E19. At E19, germ cell numbers were reduced in both trkA and trkC gene KO mice when compared to wild-type animals. Apoptosis was evaluated in testes of wild-type, trkC gene KO, and trkA gene KO mice to determine if the alteration in germ cell numbers at each developmental age was influenced by different patterns of germ cell survival or apoptosis. No differences were found in germ cell apoptosis during embryonic testis development. Interestingly, trkA gene KO mice that survived to Postnatal Day 19 had a 10-fold increase in germ cell apoptosis when compared to germ cells in wild-type mice. Evaluation of other morphological testis parameters demonstrated that trkC KO testes had reduced interstitial area at E13, reduced number of seminiferous cords at E14, and reduced seminiferous cord area at E19. The trkA gene KO testes had a reduction in the number of seminiferous cords at E14. Histology of both trkA and trkC gene KO testes demonstrated that these gonads appear to be developmentally delayed when compared to their wild-type testis counterparts at E13 during testis development. The current study demonstrates that both trkA and trkC neurotropin receptors influence germ cell numbers during testis development and events such as seminiferous cord formation.
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Affiliation(s)
- Andrea S Cupp
- Neural Development Group, Mouse Cancer Genetics Program, National Cancer Institute, Fredrick, Maryland 21701, USA
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148
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Yang B, Slonimsky JD, Birren SJ. A rapid switch in sympathetic neurotransmitter release properties mediated by the p75 receptor. Nat Neurosci 2002; 5:539-45. [PMID: 11992117 DOI: 10.1038/nn0602-853] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cardiac function is modulated by norepinephrine release from innervating sympathetic neurons. These neurons also form excitatory connections onto cardiac myocytes in culture. Here we report that brain-derived neurotrophic factor (BDNF) altered the neurotransmitter release properties of these sympathetic neuron-myocyte connections in rodent cell culture, leading to a rapid shift from excitatory to inhibitory cholinergic transmission in response to neuronal stimulation. Fifteen minutes of BDNF perfusion was sufficient to cause this shift to inhibitory transmission, indicating that BDNF promotes preferential release of acetylcholine in response to neuronal stimulation. We found that p75(-/-) neurons did not release acetylcholine in response to BDNF and that neurons overexpressing p75 showed increased cholinergic transmission, indicating that the actions of BDNF are mediated through the p75 neurotrophin receptor. Our findings indicate that p75 is involved in modulating the release of distinct neurotransmitter pools, resulting in a functional switch between excitatory and inhibitory neurotransmission in individual neurons.
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Affiliation(s)
- Bo Yang
- Department of Biology, Volen Center for Complex Systems, 415 South St., M/S 008, Brandeis University, Waltham, Massachusetts 02454, USA
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149
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150
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Mamidipudi V, Wooten MW. Dual role for p75(NTR) signaling in survival and cell death: can intracellular mediators provide an explanation? J Neurosci Res 2002; 68:373-84. [PMID: 11992464 DOI: 10.1002/jnr.10244] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Several recent reports support a dual role of p75(NTR) in cell death, as well as survival, depending on the physiological or developmental stage of the cells. Coexpression of the TrkA receptor with p75(NTR) further enhances the complexity of nerve growth factor (NGF) signaling. Recent identification of serine/threonine kinases that interact with the p75(NTR) provides an explanation for the lack of an apparent kinase domain needed for signaling. In this report, we review the possible roles of the intracellular proteins that directly interact with the p75(NTR), atypical protein kinase C (PKC) binding protein, p62 and second messengers in the functional antagonism exhibited by TrkA and p75(NTR) with an emphasis on the nuclear factor-kappa B activation pathway.
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Affiliation(s)
- Vidya Mamidipudi
- Department of Biological Sciences, Program in Cell and Molecular Biosciences, Auburn University, Auburn, Alabama 36849, USA
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