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Sabio G, Cerezo-Guisado MI, Del Reino P, Iñesta-Vaquera FA, Rousseau S, Arthur JSC, Campbell DG, Centeno F, Cuenda A. p38gamma regulates interaction of nuclear PSF and RNA with the tumour-suppressor hDlg in response to osmotic shock. J Cell Sci 2010; 123:2596-604. [PMID: 20605917 DOI: 10.1242/jcs.066514] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Activation of p38γ modulates the integrity of the complex formed by the human discs large protein (hDlg) with cytoskeletal proteins, which is important for cell adaptation to changes in environmental osmolarity. Here we report that, in response to hyperosmotic stress, p38γ also regulates formation of complexes between hDlg and the nuclear protein polypyrimidine tract-binding protein-associated-splicing factor (PSF). Following osmotic shock, p38γ in the cell nucleus increases its association with nuclear hDlg, thereby causing dissociation of hDlg-PSF complexes. Moreover, hDlg and PSF bind different RNAs; in response to osmotic shock, p38γ causes hDlg-PSF and hDlg-RNA dissociation independently of its kinase activity. These findings identify a novel nuclear complex and suggest a previously unreported function of p38γ, which is independent of its catalytic activity and could affect mRNA processing and/or gene transcription to aid cell adaptation to osmolarity changes in the environment.
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Affiliation(s)
- Guadalupe Sabio
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Campus de Cantoblanco, 28049 Madrid, Spain
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52
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Hou SW, Zhi HY, Pohl N, Loesch M, Qi XM, Li RS, Basir Z, Chen G. PTPH1 dephosphorylates and cooperates with p38gamma MAPK to increase ras oncogenesis through PDZ-mediated interaction. Cancer Res 2010; 70:2901-10. [PMID: 20332238 DOI: 10.1158/0008-5472.can-09-3229] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Protein phosphatases are believed to coordinate with kinases to execute biological functions, but examples of such integrated activities, however, are still missing. In this report, we have identified protein tyrosine phosphatase H1 (PTPH1) as a specific phosphatase for p38gamma mitogen-activated protein kinase (MAPK) and shown their cooperative oncogenic activity through direct binding. p38gamma, a Ras effector known to act independent of its phosphorylation, was first shown to require its unique PDZ-binding motif to increase Ras transformation. Yeast two-hybrid screening and in vitro and in vivo analyses further identified PTPH1 as a specific p38gamma phosphatase through PDZ-mediated binding. Additional experiments showed that PTPH1 itself plays a role in Ras-dependent malignant growth in vitro and/or in mice by a mechanism depending on its p38gamma-binding activity. Moreover, Ras increases both p38gamma and PTPH1 protein expression and there is a coupling of increased p38gamma and PTPH1 protein expression in primary colon cancer tissues. These results reveal a coordinative oncogenic activity of a MAPK with its specific phosphatase and suggest that PDZ-mediated p38gamma/PTPH1 complex may be a novel target for Ras-dependent malignancies.
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Affiliation(s)
- Song-Wang Hou
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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53
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Schindler EM, Hindes A, Gribben EL, Burns CJ, Yin Y, Lin MH, Owen RJ, Longmore GD, Kissling GE, Arthur JSC, Efimova T. p38delta Mitogen-activated protein kinase is essential for skin tumor development in mice. Cancer Res 2009; 69:4648-55. [PMID: 19458068 DOI: 10.1158/0008-5472.can-08-4455] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Activating Ras mutations occur in a large portion of human tumors. Yet, the signaling pathways involved in Ras-induced tumor formation remain incompletely understood. The mitogen-activated protein kinase pathways are among the best studied Ras effector pathways. The p38 mitogen-activated protein kinase isoforms are important regulators of key biological processes including cell proliferation, differentiation, survival, inflammation, senescence, and tumorigenesis. However, the specific in vivo contribution of individual p38 isoforms to skin tumor development has not been elucidated. Recent studies have shown that p38delta, a p38 family member, functions as an important regulator of epidermal keratinocyte differentiation and survival. In the present study, we have assessed the effect of p38delta deficiency on skin tumor development in vivo by subjecting p38delta knockout mice to a two-stage 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate chemical skin carcinogenesis protocol. We report that mice lacking p38delta gene exhibited a marked resistance to development of 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate-induced skin papillomas, with increased latency and greatly reduced incidence, multiplicity, and size of tumors compared with wild-type mice. Our data suggest that the underlying mechanism for reduced susceptibility to skin carcinogenesis in p38delta-null mice involves a defect in proliferative response associated with aberrant signaling through the two major transformation-promoting pathways: extracellular signal-regulated kinase 1/2-activator protein 1 and signal transducer and activator of transcription 3. These findings strongly suggest an in vivo role for p38delta in promoting cell proliferation and tumor development in epidermis and may have therapeutic implication for skin cancer.
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Affiliation(s)
- Eva M Schindler
- Division of Dermatology and Renal Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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54
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Increased tyrosine phosphorylation of PSD-95 by Src family kinases after brain ischaemia. Biochem J 2009; 417:277-85. [PMID: 18721130 DOI: 10.1042/bj20080004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PSD (postsynaptic density)-95, a scaffold protein that tethers NMDA (N-methyl-D-aspartate) receptors to signal molecules, is implicated in pathological events resulting from excitotoxicity. The present study demonstrates that brain ischaemia and reperfusion increase the tyrosine phosphorylation of PSD-95 in the rat hippocampus. PP2, a specific inhibitor of SrcPTKs (Src family protein tyrosine kinases), prevents the ischaemia-induced increases not only in the tyrosine phosphorylation of PSD-95, but also in the interaction between PSD-95 and Src kinases. PSD-95 is phosphorylated either by purified Src/Fyn kinases in vitro or by co-expression of constitutively active Src/Fyn in COS7 cells. The results suggest that SrcPTKs are involved in PSD-95 phosphorylation. The single Tyr(523) mutation to phenylalanine (Y523F) reduces the Src/Fyn-mediated phosphorylation of PSD-95 in COS7 cells and in vitro. As shown with a rabbit polyclonal antibody against phospho-PSD-95 (Tyr(523)), Tyr(523) phosphorylation is responsible for the increased tyrosine phosphorylation of PSD-95 induced by ischaemia in the rat hippocampus. In cultured hippocampal neurons, overexpression of PSD-95 Y523F, but not PSD-95 Y533F, abolishes the facilitating effect of PSD-95 on the glutamate- or NMDA-mediated currents, implying that PSD-95 Tyr(523) phosphorylation contributes to the post-ischaemic over-activation of NMDA receptors. Thus the present study reveals an additional mechanism for the regulation of PSD-95 by tyrosine phosphorylation. This mechanism may be of pathological significance since it is associated with excitotoxicity in the ischaemic brain.
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Iñesta-Vaquera FA, Centeno F, del Reino P, Sabio G, Peggie M, Cuenda A. Proteolysis of the tumour suppressor hDlg in response to osmotic stress is mediated by caspases and independent of phosphorylation. FEBS J 2008; 276:387-400. [DOI: 10.1111/j.1742-4658.2008.06783.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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56
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Fragoso G, Haines JD, Roberston J, Pedraza L, Mushynski WE, Almazan G. p38 mitogen-activated protein kinase is required for central nervous system myelination. Glia 2007; 55:1531-41. [PMID: 17729284 DOI: 10.1002/glia.20567] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The p38 MAPKs are a family of kinases that regulate a number of cellular functions including cell migration, proliferation, and differentiation. Here, we report that p38 regulates oligodendrocyte differentiation. Inhibition of p38 with PD169316 and SB203580 prevented accumulation of protein and mRNA of cell-stage specific markers characteristic of differentiated oligodendrocytes, including myelin basic protein, myelin-associated glycoprotein, and the glycosphingolipids, galactosylceramide and sulfatide. In addition, the cell cycle regulator p27(kip1) and the transcription factor Sox10 were also significantly reduced. Most significantly, p38 inhibitors completely and irreversibly blocked myelination of dorsal root ganglion neurons by oligodendrocytes and prevented the axolemmal organization of the axo-glial adhesion molecule Caspr. Our results suggest a role(s) for this kinase in key regulatory steps in the maturation of OLGs and initiation of myelination.
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Affiliation(s)
- Gabriela Fragoso
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
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57
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Clark JE, Sarafraz N, Marber MS. Potential of p38-MAPK inhibitors in the treatment of ischaemic heart disease. Pharmacol Ther 2007; 116:192-206. [PMID: 17765316 DOI: 10.1016/j.pharmthera.2007.06.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 06/14/2007] [Indexed: 11/25/2022]
Abstract
Chronic heart failure is debilitating, often fatal, expensive to treat and common. In most patients it is a late consequence of myocardial infarction (MI). The intracellular signals following infarction that lead to diminished contractility, apoptosis, fibrosis and ultimately heart failure are not fully understood but probably involve p38-mitogen activated protein kinases (p38), a family of serine/threonine kinases which, when activated, cause cardiomyocyte contractile dysfunction and death. Pharmacological inhibitors of p38 suppress inflammation and are undergoing clinical trials in rheumatoid arthritis, Chrohn's disease, psoriasis and surgery-induced tissue injury. In this review, we discuss the mechanisms, circumstances and consequences of p38 activation in the heart. The purpose is to evaluate p38 inhibition as a potential therapy for ischaemic heart disease.
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Affiliation(s)
- James E Clark
- The Cardiovascular Division, King's College London, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH, United Kingdom
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58
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Safdar A, Yardley NJ, Snow R, Melov S, Tarnopolsky MA. Global and targeted gene expression and protein content in skeletal muscle of young men following short-term creatine monohydrate supplementation. Physiol Genomics 2007; 32:219-28. [PMID: 17957000 DOI: 10.1152/physiolgenomics.00157.2007] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Creatine monohydrate (CrM) supplementation has been shown to increase fat-free mass and muscle power output possibly via cell swelling. Little is known about the cellular response to CrM. We investigated the effect of short-term CrM supplementation on global and targeted mRNA expression and protein content in human skeletal muscle. In a randomized, placebo-controlled, crossover, double-blind design, 12 young, healthy, nonobese men were supplemented with either a placebo (PL) or CrM (loading phase, 20 g/day x 3 days; maintenance phase, 5 g/day x 7 days) for 10 days. Following a 28-day washout period, subjects were put on the alternate supplementation for 10 days. Muscle biopsies of the vastus lateralis were obtained and were assessed for mRNA expression (cDNA microarrays + real-time PCR) and protein content (Kinetworks KPKS 1.0 Protein Kinase screen). CrM supplementation significantly increased fat-free mass, total body water, and body weight of the participants (P < 0.05). Also, CrM supplementation significantly upregulated (1.3- to 5.0-fold) the mRNA content of genes and protein content of kinases involved in osmosensing and signal transduction, cytoskeleton remodeling, protein and glycogen synthesis regulation, satellite cell proliferation and differentiation, DNA replication and repair, RNA transcription control, and cell survival. We are the first to report this large-scale gene expression in the skeletal muscle with short-term CrM supplementation, a response that suggests changes in cellular osmolarity.
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Affiliation(s)
- Adeel Safdar
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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59
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Schett G, Zwerina J, Firestein G. The p38 mitogen-activated protein kinase (MAPK) pathway in rheumatoid arthritis. Ann Rheum Dis 2007; 67:909-16. [PMID: 17827184 PMCID: PMC2754165 DOI: 10.1136/ard.2007.074278] [Citation(s) in RCA: 208] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chronic inflammatory processes are based on a sustained and tightly regulated communication network among different cells types. This network comprises extracellular mediators such as cytokines, chemokines and matrix-degrading proteases, which orchestrate the participation of cells in the chronic inflammatory process. The mirrors of this outside communication world are intracellular transcription factor pathways, which shuttle information about inflammatory stimuli to the cell nucleus. This review examines the function of one key signal transduction pathway of inflammation--the p38 mitogen-activated protein kinases (p38MAPK). The signalling pathway is considered as crucial for the induction and maintenance of chronic inflammation, and its components thus emerge as interesting molecular targets of small molecule inhibitors for controlling inflammation. This review not only summarises the current knowledge of activation, regulation and function of the p38MAPK pathway but also examines the role of this pathway in clinical disease. It gives an overview of current evidence of p38MAPK activation in inflammatory arthritis and elaborates the key molecular determinants which contribute to p38MAPK activation in joint disease.
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Affiliation(s)
- G Schett
- Department of Internal Medicine III, University of Erlangen, D-91054 Erlangen, Germany.
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60
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Bourgin P, Fabre V, Huitrón-Reséndiz S, Henriksen SJ, Prospero-Garcia O, Criado JR, de Lecea L. Cortistatin promotes and negatively correlates with slow-wave sleep. Eur J Neurosci 2007; 26:729-38. [PMID: 17686045 DOI: 10.1111/j.1460-9568.2007.05696.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Sleep need is characterized by the level of slow-wave activity (SWA) and increases with time spent awake. The molecular nature of this sleep homeostatic process is practically unknown. Here, we show that intracerebroventricular administration of the neuropeptide, cortistatin (CST-14), enhances EEG synchronization by selectively promoting deep slow-wave sleep (SWS) during both the light and dark period in rats. CST-14 also increases the level of slow-wave activity (SWA) within deep SWS during the first two hours following CST-14 administration. Steady-state levels of preprocortistatin mRNA oscillate during the light:dark cycle and are four-fold higher upon total 24-h sleep deprivation, returning progressively to normal levels after eight hours of sleep recovery. Preprocortistatin mRNA is expressed upon sleep deprivation in a particular subset of cortical interneurons that colocalize with c-fos. In contrast, the number of CST-positive cells coexpressing pERK1/2 decreases under sleep deprivation. The capacity of CST-14 to increase SWA, together with preprocortistatin's inverse correlation with time spent in SWS, suggests a potential role in sleep homeostatic processes.
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Affiliation(s)
- Patrice Bourgin
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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61
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Khurana RC, Devaud LL. Sex differences in neurotransmission parameters in response to repeated mild restraint stress exposures in intact male, female and ovariectomised female rats. J Neuroendocrinol 2007; 19:511-20. [PMID: 17532795 DOI: 10.1111/j.1365-2826.2007.01557.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The present study determined whether a repeated mild restraint stress exposure would differentially alter neuronal activity in male and female rats to gain insights into neurobiological substrates involved in sex differences in stress-induced behavioural responses. In our first set of experiments, we used Western blot analysis to determine whether alterations in several synaptic proteins were elicited by the repeated stress treatment. We found bidirectional changes in synaptophysin levels in female cerebral cortex and hippocampus that diverged between intact and ovariectomised females. There were persistent elevations in spinophilin levels in the male, but not female, hippocampus following the repeated mild restraint stress exposure. By contrast, levels of the NMDA receptor scaffolding protein, PSD-95, were altered only in intact female cerebral cortex and ovariectomised female hippocampus. We next used immunohistochemical evaluation of Fos expression as a marker for neuronal activation. We found significant increases in Fos immunoreactivity in all sex conditions across multiple brain regions in response to the repeated mild stress. Fos protein induction was greatest in the frontal cortex, piriform cortex and amygdala, with the degree of induction varying by sex condition. Fos induction was dramatically higher in amygdala and piriform cortex only in intact females following repeated stress compared to a single restraint stress exposure, suggestive of sensitisation rather than habituation. By contrast, the frontal cortex of intact and ovariectomised females showed habituation to the repeated stressor. Males displayed modest sensitisation in both the frontal cortex and dentate gyrus with no changes in other brain areas. Taken together, these findings show that exposure to a mild repeated stress results in sex differences in synaptic adaptations and patterns of brain activation that likely contribute to observed sex differences in stress-induced behaviours. This approach provides valuable insights into interactions between the hormonal milieu and responses to a repeated mild stress, and further supports the importance of considering hormonal status in treatment of stress-related disorders.
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Affiliation(s)
- R C Khurana
- Department of Pharmaceutical Sciences, College of Pharmacy and Biomedical Research Institute, Idaho State University, Pocatello, ID 83209-8334, USA
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62
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Cuenda A, Rousseau S. p38 MAP-kinases pathway regulation, function and role in human diseases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1358-75. [PMID: 17481747 DOI: 10.1016/j.bbamcr.2007.03.010] [Citation(s) in RCA: 997] [Impact Index Per Article: 58.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 03/13/2007] [Accepted: 03/19/2007] [Indexed: 11/28/2022]
Abstract
Mammalian p38 mitogen-activated protein kinases (MAPKs) are activated by a wide range of cellular stresses as well as in response to inflammatory cytokines. There are four members of the p38MAPK family (p38alpha, p38beta, p38gamma and p38delta) which are about 60% identical in their amino acid sequence but differ in their expression patterns, substrate specificities and sensitivities to chemical inhibitors such as SB203580. A large body of evidences indicates that p38MAPK activity is critical for normal immune and inflammatory response. The p38MAPK pathway is a key regulator of pro-inflammatory cytokines biosynthesis at the transcriptional and translational levels, which makes different components of this pathway potential targets for the treatment of autoimmune and inflammatory diseases. However, recent studies have shed light on the broad effect of p38MAPK activation in the control of many other aspects of the physiology of the cell, such as control of cell cycle or cytoskeleton remodelling. Here we focus on these emergent roles of p38MAPKs and their implication in different pathologies.
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Affiliation(s)
- Ana Cuenda
- MRC Protein Phosphorylation Unit, College of life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
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63
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Ito H, Usuda N, Atsuzawa K, Iwamoto I, Sudo K, Katoh-Semba R, Mizutani K, Morishita R, Deguchi T, Nozawa Y, Asano T, Nagata KI. Phosphorylation by extracellular signal-regulated kinase of a multidomain adaptor protein, vinexin, at synapses. J Neurochem 2007; 100:545-54. [PMID: 17241162 DOI: 10.1111/j.1471-4159.2006.04222.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Vinexin is an adaptor protein that is supposed to play pivotal roles in cell adhesion, cytoskeletal organization and signaling. At least three splice variants, vinexinalpha, beta and gamma, have so far been reported. In spite of the possible importance of vinexin, the properties and functions of vinexin in neuronal cells are almost unknown. Here we show that vinexin isoforms are expressed in rat brain in a developmental stage-dependent manner, and that vinexinalpha is relatively abundant in the telencephalon regions of the adult rat brain. An immunohistochemical study showed the localization of vinexinalpha in neurons and glia in the rat brain. In primary cultured rat hippocampal neurons, vinexin was found to be present at synapses and filopodia in growth cones by immunofluorescent analyses. Biochemical fractionation revealed the distribution of vinexin in synaptosomes. Nerve terminal localization of vinexin was confirmed by electron microscopy. Vinexinbeta is reported to be phosphorylated by extracellular signal-regulated kinase (ERK) at Ser189, which is equivalent to Ser593 of vinexinalpha. We thus constructed a site- and phosphorylation state-specific antibody to monitor the ERK-mediated phosphorylation of vinexin. In immunofluorescent analyses, the phosphorylation was observed at synapses formed among cultured rat hippocampal neurons and it was reduced by treatment of the cells with PD98059. In an immunoelectron microscopic examination, the phosphorylation signal was mainly detected on the postsynaptic side of synapses in the rat hippocampal neurons. As active ERK was co-localized with vinexin in synapses, the ERK signal is likely to be involved in the regulation of vinexin-dependent cellular processes in synapses. On the other hand, the phosphorylation was hardly detected in neurons cultured for 3 days, suggesting the presence of a yet unidentified regulatory mechanism of vinexin at the growth cone.
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Affiliation(s)
- Hidenori Ito
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, japan
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64
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Korb A, Tohidast-Akrad M, Cetin E, Axmann R, Smolen J, Schett G. Differential tissue expression and activation of p38 MAPK alpha, beta, gamma, and delta isoforms in rheumatoid arthritis. ACTA ACUST UNITED AC 2006; 54:2745-56. [PMID: 16947383 DOI: 10.1002/art.22080] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Activation of p38 MAPK is a key signaling step in chronic inflammation. Inhibition of p38 MAPK is considered to be a promising future strategy to control inflammatory diseases, but studies of compounds to inhibit this kinase have so far been limited to investigation of their side effects. We undertook the present study to investigate which specific molecule, among 4 different isoforms of p38 MAPK (alpha, beta, gamma, and delta), is predominantly expressed and activated in inflammation. Such knowledge could allow more specific targeting of p38 MAPK in inflammatory disease. METHODS Studies were performed on inflamed tissue from patients with rheumatoid arthritis, as a prototype of inflammatory disease. The expression and activation of the alpha, beta, gamma, and delta isoforms of p38 MAPK were examined by immunoblotting, immunoprecipitation, and immunohistochemistry. RESULTS Immunoblot analysis revealed that alpha and gamma were the predominantly expressed p38 MAPK isoforms, whereas the other 2 isoforms were less frequently present. By immunohistochemistry, the expression of all p38 MAPK isoforms was localized to the synovial lining layer as well as to blood vessels. Colabeling with cell-specific markers revealed that macrophages expressed the alpha and gamma isoforms, synovial fibroblasts the beta and gamma isoforms, and granulocytes the delta isoform, whereas T lymphocytes were rarely positive for any p38 MAPK isoform. Double-labeling with isoform-specific antibody and pan-p38 antibody against the phosphorylated form of p38 MAPK showed activation of the alpha and gamma isoforms. Occasional activation of the beta isoform was also noted in the synovial lining and the endothelium, whereas the delta isoform, although expressed in pericytes around blood vessels, was not phosphorylated. This phosphorylation pattern was confirmed in immunoprecipitation studies in which activated p38 MAPK from synovial tissue extracts was identified as p38 MAPKalpha and -gamma but not p38 MAPKbeta or -delta. CONCLUSION These data show that the alpha and gamma isoforms of p38 MAPK dominate in chronic inflammation. Effective strategies to inhibit p38 MAPK should therefore aim to specifically target either or both of these isoforms.
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65
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Gardoni F, Polli F, Cattabeni F, Di Luca M. Calcium-calmodulin-dependent protein kinase II phosphorylation modulates PSD-95 binding to NMDA receptors. Eur J Neurosci 2006; 24:2694-704. [PMID: 17156196 DOI: 10.1111/j.1460-9568.2006.05140.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
At the postsynaptic membrane of excitatory synapses, NMDA-type receptors are bound to scaffolding and signalling proteins that regulate the strength of synaptic transmission. The cytosolic tails of the NR2A and NR2B subunits of NMDA receptor bind to calcium-calmodulin-dependent protein kinase II (CaMKII) and to members of the MAGUK family such as PSD-95. In particular, although NR2A and NR2B subunits are highly homologous, the sites of their interaction with CaMKII as well as the regulation of this binding differ. We identified PSD-95 phosphorylation as a molecular mechanism responsible for the dynamic regulation of the interaction of both PSD-95 and CaMKII with the NR2A subunit. CaMKII-dependent phosphorylation of PSD-95 occurs both in vitro, in GST-PSD-95 fusion proteins phosphorylated by purified active CaMKII, and in vivo, in transfected COS-7 as well as in cultured hippocampal neurons. We identified Ser73 as major phosphorylation site within the PDZ1 domain of PSD-95, as confirmed by point mutagenesis experiments and by using a phospho-specific antibody. PSD-95 Ser73 phosphorylation causes NR2A dissociation from PSD-95, while it does not interfere with NR2B binding to PSD-95. These results identify CaMKII-dependent phosphorylation of the PDZ1 domain of PSD-95 as a mechanism regulating the signalling transduction pathway downstream NMDA receptor.
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Affiliation(s)
- Fabrizio Gardoni
- Center of Excellence on Neurodegenerative Diseases and Department of Pharmacological Sciences, University of Milan, via Balzaretti 9, 20133 Milano, Italy.
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66
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Hamel M, Kanyi D, Cipolle MD, Lowe-Krentz L. Active stress kinases in proliferating endothelial cells associated with cytoskeletal structures. ACTA ACUST UNITED AC 2006; 13:157-70. [PMID: 16840172 DOI: 10.1080/10623320600760191] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
It has become increasingly clear that stress-activated protein kinases have cytoplasmic substrates in addition to well-established transcription factor substrates in cell nuclei. The present study documented specific cytoplasmic locations of these enzymes in proliferating vascular cells. Immunofluorescent staining for active c-jun NH2-terminal kinase (JNK), the precipitation of JNK with microfilaments, and the loss of fiber-associated active JNK after cytochalasin treatment, but not nocodazole treatment, together indicate that active JNK is associated with stress fibers. The lack of complete scaffold colocalization and the total lack of immediate upsteam kinase colocalization along with the inability of JNK inhibitors to alter JNK-microfilament associations suggest that the microfilament association is not simply involved in enzyme activation. In addition, active p38 was found along with vinculin in focal adhesions. Although the p38 in focal adhesions could also be disrupted by cytochalasin treatment, it remained stable after nocodazole treatment. These results support the hypothesis that vascular cell stress kinase enzymes are important for signal transduction in the cytoplasm. The localization of active stress-activated protein kinases to specific cytoskeletal structures in proliferating cells suggests that subsets of these enzymes are involved in signal transduction to and/or from the cytoskeleton under conditions that include vascular cell proliferation.
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Affiliation(s)
- Marianne Hamel
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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67
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Yoon S, Seger R. The extracellular signal-regulated kinase: multiple substrates regulate diverse cellular functions. Growth Factors 2006; 24:21-44. [PMID: 16393692 DOI: 10.1080/02699050500284218] [Citation(s) in RCA: 930] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The extracellular signal-regulated kinase (ERK) cascade is a central pathway that transmits signals from many extracellular agents to regulate cellular processes such as proliferation, differentiation and cell cycle progression. The signaling via the ERK cascade is mediated by sequential phosphorylation and activation of protein kinases in the different tiers of the cascade. Although the main core phosphorylation chain of the cascade includes Raf kinases, MEK1/2, ERK1/2 (ERKs) and RSKs, other alternatively spliced forms and distinct components exist in the different tiers, and participate in ERK signaling under specific conditions. These components enhance the complexity of the ERK cascade and thereby, enable the wide variety of functions that are regulated by it. Another factor that is important for the dissemination of ERKs' signals is the multiplicity of the cascade's substrates, which include transcription factors, protein kinases and phosphatases, cytoskeletal elements, regulators of apoptosis, and a variety of other signaling-related molecules. About 160 substrates have already been discovered for ERKs, and the list of these substrates, as well as the function and mechanism of activation of representative substrates, are described in the current review. Many of these substrates are localized in the nucleus, and seem to participate in the regulation of transcription upon stimulation. However, other substrates are found in the cytosol as well as in other cellular organelles, and those are responsible for processes such as translation, mitosis and apoptosis. Understanding of these processes may provide a full picture of the distinct, and even opposing cellular processes that are regulated by the ERK cascade.
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Affiliation(s)
- Seunghee Yoon
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
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68
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Roselli F, Tirard M, Lu J, Hutzler P, Lamberti P, Livrea P, Morabito M, Almeida OFX. Soluble beta-amyloid1-40 induces NMDA-dependent degradation of postsynaptic density-95 at glutamatergic synapses. J Neurosci 2006; 25:11061-70. [PMID: 16319306 PMCID: PMC6725651 DOI: 10.1523/jneurosci.3034-05.2005] [Citation(s) in RCA: 224] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Amyloid-beta (Abeta) has been implicated in memory loss and disruption of synaptic plasticity observed in early-stage Alzheimer's disease. Recently, it has been shown that soluble Abeta oligomers target synapses in cultured rat hippocampal neurons, suggesting a direct role of Abeta in the regulation of synaptic structure and function. Postsynaptic density-95 (PSD-95) is a postsynaptic scaffolding protein that plays a critical role in synaptic plasticity and the stabilization of AMPA (AMPARs) and NMDA (NMDARs) receptors at synapses. Here, we show that exposure of cultured cortical neurons to soluble oligomers of Abeta(1-40) reduces PSD-95 protein levels in a dose- and time-dependent manner and that the Abeta1(1-40)-dependent decrease in PSD-95 requires NMDAR activity. We also show that the decrease in PSD-95 requires cyclin-dependent kinase 5 activity and involves the proteasome pathway. Immunostaining analysis of cortical cultured neurons revealed that Abeta treatment induces concomitant decreases in PSD-95 at synapses and in the surface expression of the AMPAR glutamate receptor subunit 2. Together, these data suggest a novel pathway by which Abeta triggers synaptic dysfunction, namely, by altering the molecular composition of glutamatergic synapses.
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Affiliation(s)
- F Roselli
- Max Planck Institute of Psychiatry, 80804 Munich, Germany
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69
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Kuma Y, Sabio G, Bain J, Shpiro N, Márquez R, Cuenda A. BIRB796 Inhibits All p38 MAPK Isoforms in Vitro and in Vivo. J Biol Chem 2005; 280:19472-9. [PMID: 15755732 DOI: 10.1074/jbc.m414221200] [Citation(s) in RCA: 241] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The compound BIRB796 inhibits the stress-activated protein kinases p38alpha and p38beta and is undergoing clinical trials for the treatment of inflammatory diseases. Here we report that BIRB796 also inhibits the activity and the activation of SAPK3/p38gamma. This occurs at higher concentrations of BIRB796 than those that inhibit p38alpha and p38beta and at lower concentrations than those that inhibit the activation of JNK isoforms. We also show that at these concentrations, BIRB796 blocks the stress-induced phosphorylation of the scaffold protein SAP97, further establishing that this is a physiological substrate of SAPK3/p38gamma. Our results demonstrate that BIRB796, in combination with SB203580, a compound that inhibits p38alpha and p38beta, but not the other p38 isoforms, can be used to identify physiological substrates of SAPK3/p38gamma as well as those of p38alpha and p38beta.
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Affiliation(s)
- Yvonne Kuma
- Medical Research Council Protein Phosphorylation Unit, University of Dundee, Scotland, UK
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70
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Tang J, Qi X, Mercola D, Han J, Chen G. Essential role of p38gamma in K-Ras transformation independent of phosphorylation. J Biol Chem 2005; 280:23910-7. [PMID: 15851477 PMCID: PMC1224721 DOI: 10.1074/jbc.m500699200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
MAPK cascades play the critical role in regulating Ras oncogene activity by phosphorylation-dependent mechanisms. Whereas the ERK MAPK pathway is required for Ras transformation, our previous works established that the p38 activity is inhibitory to Ras signaling in both experimental and ras-mutated cancer cells (Chen, G., Hitomi, M., Han, J., and Stacey, D. W. (2000) J. Biol. Chem. 275, 38973-38980; Qi, X., Tang, J., Pramanik, R., Schultz, R. M., Shirasawa, S., Sasazuki, T., Han, J., and Chen, G. (2004) J. Biol. Chem., 279, 22138-22144). Here we report that K-Ras activated p38gamma, a p38 MAPK family member, by inducing its expression without increasing its phosphorylation and that depletion of induced p38gamma suppressed Ras transformation in rat intestinal epithelial cells. This p38gamma activity contrasts with that of its family member, p38alpha, which is activated by Ras through phosphorylation, leading to an inhibition of Ras transformation. Mechanistic analyses showed that unphosphorylated p38gamma may promote Ras transformation through an increased complex formation with ERK proteins. Significantly, functional p38gamma protein was expressed only in K-ras-mutated human colon cancer cells, and p38gamma transcripts were ubiquitously increased in a set of primary human colon cancer tissues. These studies thus demonstrate the essential role of p38gamma in K-Ras transformation independent of phosphorylation, and elevated p38gamma may serve as a novel diagnostic marker and therapeutic target for human colon cancer.
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Affiliation(s)
- Jun Tang
- Department of Radiation Oncology
| | | | - Dan Mercola
- Department of Cancer Gene Therapy, Sidney Kimmel Cancer Center, San Diego, CA 92121
| | - Jiahuai Han
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037
| | - Guan Chen
- Department of Radiation Oncology
- Department of Pharmacology and Experimental Therapeutics
- Program in Molecular Biology and Biochemistry, Loyola University of Chicago, Maywood, IL 60153
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71
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Sabio G, Arthur JSC, Kuma Y, Peggie M, Carr J, Murray-Tait V, Centeno F, Goedert M, Morrice NA, Cuenda A. p38gamma regulates the localisation of SAP97 in the cytoskeleton by modulating its interaction with GKAP. EMBO J 2005; 24:1134-45. [PMID: 15729360 PMCID: PMC556394 DOI: 10.1038/sj.emboj.7600578] [Citation(s) in RCA: 185] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Accepted: 01/19/2005] [Indexed: 12/30/2022] Open
Abstract
Activation of the p38 MAP kinase pathways is crucial for the adaptation of mammalian cells to changes in the osmolarity of the environment. Here we identify SAP97/hDlg, the mammalian homologue of the Drosophila tumour suppressor Dlg, as a physiological substrate for the p38gamma MAP kinase (SAPK3/p38gamma) isoform. SAP97/hDlg is a scaffold protein that forms multiprotein complexes with a variety of proteins and is targeted to the cytoskeleton by its association with the protein guanylate kinase-associated protein (GKAP). The SAPK3/p38gamma-catalysed phosphorylation of SAP97/hDlg triggers its dissociation from GKAP and therefore releases it from the cytoskeleton. This is likely to regulate the integrity of intercellular-junctional complexes, and cell shape and volume in response to osmotic stress.
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Affiliation(s)
- Guadalupe Sabio
- MRC Protein Phosphorylation Unit, University of Dundee, Dundee, UK
- Departmento Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | | | - Yvonne Kuma
- MRC Protein Phosphorylation Unit, University of Dundee, Dundee, UK
| | - Mark Peggie
- MRC Protein Phosphorylation Unit, University of Dundee, Dundee, UK
| | - Julia Carr
- MRC Protein Phosphorylation Unit, University of Dundee, Dundee, UK
| | | | - Francisco Centeno
- Departmento Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Michel Goedert
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK
| | | | - Ana Cuenda
- MRC Protein Phosphorylation Unit, University of Dundee, Dundee, UK
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dow St., Dundee DD1 5EH, UK. Tel.: +44 1382 344241; Fax: +44 1382 223778; E-mail:
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Feijoo C, Campbell DG, Jakes R, Goedert M, Cuenda A. Evidence that phosphorylation of the microtubule-associated protein Tau by SAPK4/p38δ at Thr50 promotes microtubule assembly. J Cell Sci 2005; 118:397-408. [PMID: 15632108 DOI: 10.1242/jcs.01655] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphorylation regulates both normal and pathological Tau functioning. This microtubule-associated protein plays a role in the organization and integrity of the neuronal cytoskeleton under normal conditions and becomes hyperphosphorylated and aggregated in a number of neurodegenerative diseases referred to as tauopathies. In this study, we identify and compare the residues in human Tau phosphorylated in vitro by all four p38 MAPK isoforms, and study the regulation of the phosphorylation of Thr50, under conditions where p38 MAPKs are active in cells. Through biochemical analysis, loss of function studies and analysis of endogenous and overexpressed Tau proteins, we show that SAPK4/p38δ is the major kinase phosphorylating Thr50 in Tau, when cells are exposed to osmotic stress. We also show that mutation of Thr50 to glutamic acid, which mimics phosphorylation, increases the ability of Tau to promote tubulin polymerisation in vitro and in vivo. Moreover, we show that Thr50 is phosphorylated in filamentous Tau from Alzheimer's disease brain. These findings suggest a role for Tau in the adaptative response of neurons to stress and indicate that SAPK4/p38δ and/or SAPK3/p38δ may contribute to the hyperphosphorylation of Tau in the human tauopathies.
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Affiliation(s)
- Carmen Feijoo
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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73
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Court NW, Ingley E, Klinken SP, Bogoyevitch MA. Outer membrane protein 25-a mitochondrial anchor and inhibitor of stress-activated protein kinase-3. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1744:68-75. [PMID: 15878399 DOI: 10.1016/j.bbamcr.2004.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2004] [Revised: 11/29/2004] [Accepted: 11/29/2004] [Indexed: 10/26/2022]
Abstract
Stress-activated protein kinase-3 (SAPK3) is unique amongst the mitogen-activated protein kinase (MAPK) family with its C-terminal 5 amino acids directing interaction with the PDZ domain-containing substrates alpha1-Syntrophin and SAP90/PSD95. Here, we identify three additional PDZ domain-containing binding partners, Lin-7C, Scribble, and outer membrane protein 25 (OMP25). This latter protein is localised together with SAPK3 at the mitochondria but it is not a SAPK3 substrate. Instead, OMP25 inhibits SAPK3 activity towards PDZ domain-containing substrates such as alpha1-Syntrophin and substrates without PDZ domains such as the mitochondrial protein Sab. This is a new mechanism for the regulation of SAPK3 and suggests that its intracellular activity should not be solely assessed by its phosphorylation status.
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Affiliation(s)
- Naomi W Court
- Cell Signalling Laboratory, Biochemistry and Molecular Biology (M310), University of Western Australia, Western Australia 6009, Australia
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May P, Rohlmann A, Bock HH, Zurhove K, Marth JD, Schomburg ED, Noebels JL, Beffert U, Sweatt JD, Weeber EJ, Herz J. Neuronal LRP1 functionally associates with postsynaptic proteins and is required for normal motor function in mice. Mol Cell Biol 2004; 24:8872-83. [PMID: 15456862 PMCID: PMC517900 DOI: 10.1128/mcb.24.20.8872-8883.2004] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The LDL receptor-related protein 1 (LRP1) is a multifunctional cell surface receptor that is highly expressed on neurons. Neuronal LRP1 in vitro can mediate ligand endocytosis, as well as modulate signal transduction processes. However, little is known about its role in the intact nervous system. Here, we report that mice that lack LRP1 selectively in differentiated neurons develop severe behavioral and motor abnormalities, including hyperactivity, tremor, and dystonia. Since their central nervous systems appear histoanatomically normal, we suggest that this phenotype is likely attributable to abnormal neurotransmission. This conclusion is supported by studies of primary cultured neurons that show that LRP1 is present in close proximity to the N-methyl-D-aspartate (NMDA) receptor in dendritic synapses and can be coprecipitated with NMDA receptor subunits and the postsynaptic density protein PSD-95 from neuronal cell lysates. Moreover, treatment with NMDA, but not dopamine, reduces the interaction of LRP1 with PSD-95, indicating that LRP1 participates in transmitter-dependent postsynaptic responses. Together, these findings suggest that LRP1, like other ApoE receptors, can modulate synaptic transmission in the brain.
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Affiliation(s)
- Petra May
- Zentrum für Neurowissenschaften, University of Freiburg, Albertstrabetae 23, 79104 Freiburg, Germany.
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75
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Bogoyevitch MA, Court NW. Counting on mitogen-activated protein kinases—ERKs 3, 4, 5, 6, 7 and 8. Cell Signal 2004; 16:1345-54. [PMID: 15381250 DOI: 10.1016/j.cellsig.2004.05.004] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Accepted: 05/12/2004] [Indexed: 11/19/2022]
Abstract
Signal transduction pathways in eukaryotic cells integrate diverse extracellular signals, and regulate complex biological responses such as growth, differentiation and death. One group of proline-directed Ser/Thr protein kinases, the mitogen-activated protein kinases (MAPKs), plays a central role in these signalling pathways. Much attention has focused in recent years on three subfamilies of MAPKs, the extracellular signal regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs) and the p38 MAPKs. However, the ERK family is broader than the ERK1 and ERK2 proteins that have been the subject of most studies in this area. Here we overview the work on ERKs 3 to 8, emphasising where possible their biological activities as well as distinctive biochemical properties. It is clear from these studies that these additional ERKs show similarities to ERK1 and ERK2, but with some interesting differences that challenge the paradigm of the archetypical ERK1/2 MAPK pathway.
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Affiliation(s)
- Marie A Bogoyevitch
- Cell Signalling Laboratory, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, University of Western Australia, Crawley, WA 6009, Australia.
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76
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Court NW, Kuo I, Quigley O, Bogoyevitch MA. Phosphorylation of the mitochondrial protein Sab by stress-activated protein kinase 3. Biochem Biophys Res Commun 2004; 319:130-7. [PMID: 15158451 DOI: 10.1016/j.bbrc.2004.04.148] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Indexed: 11/28/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) transduce extracellular signals into responses such as growth, differentiation, and death through their phosphorylation of specific substrate proteins. Early studies showed the consensus sequence (Pro/X)-X-(Ser/Thr)-Pro to be phosphorylated by MAPKs. Docking domains such as the "kinase interaction motif" (KIM) also appear to be crucial for efficient substrate phosphorylation. Here, we show that stress-activated protein kinase-3 (SAPK3), a p38 MAPK subfamily member, localizes to the mitochondria. Activated SAPK3 phosphorylates the mitochondrial protein Sab, an in vitro substrate of c-Jun N-terminal kinase (JNK). Sab phosphorylation by SAPK3 was dependent on the most N-terminal KIM (KIM1) of Sab and occurred primarily on Ser321. This appeared to be dependent on the position of Ser321 within Sab and the sequence immediately surrounding it. Our results suggest that SAPK3 and JNK may share a common target at the mitochondria and provide new insights into the substrate recognition by SAPK3.
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Affiliation(s)
- Naomi W Court
- Cell Signalling Laboratory, Biochemistry and Molecular Biology, University of Western Australia, Crawley, Western Australia 6009, Australia
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