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Radulovic J, Tronson NC. Protein synthesis inhibitors, gene superinduction and memory: too little or too much protein? Neurobiol Learn Mem 2007; 89:212-8. [PMID: 17904877 PMCID: PMC2323246 DOI: 10.1016/j.nlm.2007.08.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 08/14/2007] [Accepted: 08/15/2007] [Indexed: 01/11/2023]
Abstract
To date, the effects of protein synthesis inhibitors (PSI) in learning and memory processes have been attributed to translational arrest and consequent inhibition of de novo protein synthesis. Here we argue that amnesia produced by PSI can be the direct result of their abnormal induction of mRNA-a process termed gene superinduction. This action exerted by PSI involves an abundant and prolonged accumulation of mRNA transcripts of genes that are normally transiently induced. We summarize experimental evidence for the multiple mechanisms and signaling pathways mediating gene superinduction and consider its relevance for PSI-induced amnesia. This mechanistic alternative to protein synthesis inhibition is compared to models of electroconvulsive seizures and fragilexsyndrome associated with enhanced mRNA/protein levels and cognitive deficits.
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Affiliation(s)
- Jelena Radulovic
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, IL 60611, USA.
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52
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Eddy SF, Storey KB. p38MAPK regulation of transcription factor targets in muscle and heart of the hibernating bat,Myotis lucifugus. Cell Biochem Funct 2007; 25:759-65. [PMID: 17487931 DOI: 10.1002/cbf.1416] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mammalian hibernation combines a profound net metabolic rate suppression with the selective up-regulation of key genes whose protein products address specific metabolic needs of the hibernator. The signal transduction pathways and transcription factors involved in regulating hibernation-responsive gene expression are of great interest. The present study suggests an important role for the p38 mitogen-activated protein kinase (p38 MAPK) and selected downstream transcription factors under its control (CREB, ATF-2, Elk-1) in the metabolic response by skeletal muscle during hibernation of little brown bats, Myotis lucifugus. Western blotting was used to quantify both total protein and levels of the phosphorylated, active forms of p38 MAPK, CREB, ATF-2 and Elk-1 in both skeletal muscle and heart of euthermic and hibernating bats. The p38 MAPK pathway was not apparently activated in heart during torpor but skeletal muscle showed strong increases (2.2-11-fold) in the amounts of phosphorylated p38 T180/Y182, CREB S133, ATF-2T69/71 and Elk-1(S383) in the torpid versus aroused state. By contrast both total and phosphorylated levels of Elk-1 in heart were reduced during hibernation to just 30% of the euthermic values. These data implicate p38 MAPK and its transcription factor targets, CREB, ATF-2 and Elk-1 in skeletal muscle maintenance during hibernation.
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Affiliation(s)
- Sean F Eddy
- Institute of Biochemistry and Department of Chemistry, Carleton University, Ottawa, Ont., Canada K1S 5B6.
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53
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da Silva Correia J, Miranda Y, Leonard N, Hsu J, Ulevitch RJ. Regulation of Nod1-mediated signaling pathways. Cell Death Differ 2006; 14:830-9. [PMID: 17186025 DOI: 10.1038/sj.cdd.4402070] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Nod1 is a member of the NLR/Nod/CATERPILLER family. It acts as a sensor for intracellular bacteria by recognizing specific glycopeptides derived from peptidoglycan. Nod1 activation mediates distinct cellular responses including activation of MAP kinases, IL-8 release, apoptosis and suppression of several estrogen-dependent responses in MCF-7 cells. Here we have extended these studies by identifying key regulatory steps in Nod1-dependent signaling pathways. We provide multiple lines of data showing that Nod1-dependent apoptosis is a caspase 8-mediated event and that apoptosis requires RIP2. In contrast, several lines of evidence show that Nod1-dependent JNK activation and IL-8 production did not require the presence of caspase 8 but required activation of TAK1 as well as RIP2. Thus, we have identified several key control points that lie downstream of Nod1. This work provides the basis for further studies of the biological significance and regulation of the Nod1 pathway.
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Affiliation(s)
- J da Silva Correia
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA
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54
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Vergarajauregui S, Miguel AS, Puertollano R. Activation of p38 mitogen-activated protein kinase promotes epidermal growth factor receptor internalization. Traffic 2006; 7:686-98. [PMID: 16683917 PMCID: PMC1479226 DOI: 10.1111/j.1600-0854.2006.00420.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Endocytic trafficking plays an important role in the regulation of the epidermal growth factor receptor (EGFR). To address if cellular kinases regulate EGFR internalization, we used anisomycin, a potent activator of kinase cascades in mammalian cells, especially the stress-activated mitogen-activated protein (MAP) kinase subtypes. Here, we report that activation of p38 MAP kinase by anisomycin is sufficient to induce internalization of EGFR. Anisomycin and EGF employ different mechanisms to promote EGFR endocytosis as anisomycin-induced internalization does not require tyrosine kinase activity or ubiquitination of the receptor. In addition, anisomycin treatment did not result in delivery and degradation of EGFR at lysosomes. Incubation with a specific inhibitor of p38, or depletion of endogenous p38 by small interfering RNAs, abolished anisomycin-induced internalization of EGFR while having no effect on transferrin endocytosis, indicating that the effect of p38 activation on EGFR endocytosis is specific. Interestingly, inhibition of p38 activation also abolished endocytosis of EGFR induced by UV radiation. Our results reveal a novel role for p38 in the regulation of EGFR endocytosis and suggest that stimulation of EGFR internalization by p38 might represent a general mechanism to prevent generation of proliferative or anti-apoptotic signals under stress conditions.
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55
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Goyarts T, Grove N, Dänicke S. Effects of the Fusarium toxin deoxynivalenol from naturally contaminated wheat given subchronically or as one single dose on the in vivo protein synthesis of peripheral blood lymphocytes and plasma proteins in the pig. Food Chem Toxicol 2006; 44:1953-65. [PMID: 16950553 DOI: 10.1016/j.fct.2006.06.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 04/26/2006] [Accepted: 06/16/2006] [Indexed: 11/30/2022]
Abstract
Trichothecenes, such as deoxynivalenol (DON), are known to inhibit the protein synthesis in vitro by binding at the 60S subunit of eukaryotic ribosomes. Therefore, cells and tissues with high protein turnover, such as lymphocytes and the liver (albumin and fibrinogen synthesis), were suggested to react most sensitively to DON. However, to the author's knowledge this observation was not proven in vivo in pigs, which were regarded as the farm animals most susceptible to DON. A total of 31 castrated male, crossbred German Landrace x Pietrain pigs weighing approx. 40 kg were fed a DON contaminated diet (5.7 mg/kg) either acutely (one single dose) or subchronically (4 weeks) or a control diet (0.1 mg/kg). In addition, one group received an intravenous injection of 53 microg DON/kg LW. One hour after feeding, a "flooding dose" of the stable isotope l-[(2)H(5)]-phenylalanine (125 mg/kg LW) was given and frequent blood samples (permanent catheter) were collected over a 60 min period. The molar percent excess (MPE) of plasma free and protein-bound phenylalanine were measured by GC/MS. No differences could be observed in the plasma concentrations of total protein, albumin, fibrinogen and serum enzymes between the groups. On the other hand, fractional synthesis rates (FSR, %/d) of albumin were significantly decreased by 43%, 45% and 26% and FSR of lymphocytes declined by 27%, 19% and 24%, whereas fibrinogen was not significantly affected after subchronic or one single oral and intravenous DON exposure, respectively. Additionally, the absolute synthesis rate (ASR, g/d) of albumin and the proportion of albumin to total body protein synthesis were reduced in the same manner, whereas the albumin secretion time ranged between 6.8 and 34.4 min and was not affected by treatment. In conclusion, the flooding dose technique appeared to be suitable for distinguishing DON-related effects on the protein synthesis, while determination of plasma protein concentrations seemed not to be an appropriate parameter.
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Affiliation(s)
- Tanja Goyarts
- Institute of Animal Nutrition, Federal Agricultural Research Centre (FAL), Bundesallee 50, 38116 Braunschweig, Germany.
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56
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Karpova A, Mikhaylova M, Thomas U, Knöpfel T, Behnisch T. Involvement of protein synthesis and degradation in long-term potentiation of Schaffer collateral CA1 synapses. J Neurosci 2006; 26:4949-55. [PMID: 16672670 PMCID: PMC6674165 DOI: 10.1523/jneurosci.4573-05.2006] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Expression of synaptic plasticity involves the translation of mRNA into protein and, probably, active protein degradation via the proteasome pathway. Here, we report on the rapid activation of synthesis and degradation of a probe protein with the induction of long-term potentiation (LTP) in the hippocampal Schaffer collateral CA1 pathway. The proteasome inhibitor MG132 significantly reduced the field EPSP slope potentiation and LTP maintenance without acutely affecting basal synaptic transmission. To visualize protein dynamics, CA1 pyramidal cells of hippocampal slices were transfected with Semliki Forest virus particles expressing a recombinant RNA. This RNA contained the coding sequence for a degradable green fluorescence protein with a nuclear localization signal (NLS-d1EGFP) followed by a 3'- untranslated region dendritic targeting sequence. NLS-d1EGFP fluorescence remained stable in the low-frequency test stimulation but increased with LTP induction in the cell body and in most dendritic compartments of CA1 neurons. Applying anisomycin, a protein synthesis inhibitor, caused NLS-d1EGFP levels to decline; a proteasome inhibitor MG132 reversed this effect. In the presence of anisomycin, LTP induction accelerated the degradation of NLS-d1EGFP. When both inhibitors were present, NLS-d1EGFP levels remained unaffected by LTP induction. Moreover, LTP-induced acceleration of NLS-d1EGFP synthesis was blocked by rapamycin, which is consistent with the involvement of dendritic mammalian target of rapamycin in LTP-triggered translational activity. Our results clearly demonstrate that LTP induction not only leads to a rapid increase in the rate of protein synthesis but also accelerates protein degradation via the proteasome system.
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57
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Lee KH, Nishimura S, Matsunaga S, Fusetani N, Ichijo H, Horinouchi S, Yoshida M. Induction of a ribotoxic stress response that stimulates stress-activated protein kinases by 13-deoxytedanolide, an antitumor marine macrolide. Biosci Biotechnol Biochem 2006; 70:161-71. [PMID: 16428834 DOI: 10.1271/bbb.70.161] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
13-Deoxytedanolide is a structurally unique macrolide with strong antitumor activity isolated from a marine sponge. Recently, we showed that 13-deoxytedanolide bound to the large subunit of the yeast ribosome and inhibited polypeptide elongation in vitro, but the mechanism by which it exerts antitumor activity is still unknown. Here we show that 13-deoxytedanolide strongly induces plasminogen activator inhibitor 1 (PAI-1) promoter-derived gene expression. 13-Deoxytedanolide, unlike TGF-beta, did not cause apparent nuclear translocation of Smad2/3, but it relocalized the temperature-sensitive mutant of mouse p53 (p53Val153) from the cytoplasm to the nucleus at a nonpermissive temperature, suggesting that 13-deoxytedanolide inhibits protein synthesis. Indeed, the drug inhibited in vivo protein synthesis at low nanomolar concentrations and strongly activated stress-activated protein kinases such as p38 mitogen-activated protein kinase and Jun NH2-terminal protein kinase (JNK). Anisomycin, a well-known inducer of ribotoxic stress that activates both p38 and JNK, also activated PAI-1 gene expression, while other protein synthesis inhibitors that do not activate the kinases failed to do so. PAI-1 gene expression by 13-deoxytedanolide and anisomycin was blocked by SB202190, a specific inhibitor of p38, and SP600125, an inhibitor of both p38 and JNK. 13-Deoxytedanolide and anisomycin caused activation of apoptosis signal-regulating kinase 1, MKK3/MKK6, and SEK1/MKK4, the regulatory kinases upstream of p38 and JNK. These results suggest that 13-deoxytedanolide, like anisomycin, triggers a ribotoxic stress response that activates stress-activated protein kinase cascades, thereby inducing PAI-1 gene expression and apoptosis.
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Affiliation(s)
- Kun-Hyung Lee
- Department of Biotechnology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Tokyo, Japan
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58
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Wang LY, Shiozaki K. The fission yeast stress MAPK cascade regulates the pmp3+ gene that encodes a highly conserved plasma membrane protein. FEBS Lett 2006; 580:2409-13. [PMID: 16603158 DOI: 10.1016/j.febslet.2006.03.065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 03/14/2006] [Accepted: 03/22/2006] [Indexed: 10/24/2022]
Abstract
In eukaryotic organisms, stress-activated mitogen-activated protein kinases (MAPK) play crucial roles in transmitting environmental signals to regulate gene expression for cellular stress adaptation. Here we report that, in the fission yeast Schizosaccharomyces pombe, Spc1/Sty1 MAPK and the Atf1 transcription factor regulate the stress-induced expression of Pmp3, a ubiquitous small membrane protein implicated in the modulation of the plasma membrane potential. The pmp3 null mutant, as well as the spc1 and atf1 mutants, is hypersensitive to the cationic antibiotic hygromycin B. Transcriptional regulation of the Pmp3-like genes by the stress-activated MAPK may also be conserved in other eukaryotes, including plants.
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Affiliation(s)
- Ling-yu Wang
- Section of Microbiology, College of Biological Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
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59
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da Silva Correia J, Miranda Y, Austin-Brown N, Hsu J, Mathison J, Xiang R, Zhou H, Li Q, Han J, Ulevitch RJ. Nod1-dependent control of tumor growth. Proc Natl Acad Sci U S A 2006; 103:1840-5. [PMID: 16446438 PMCID: PMC1413646 DOI: 10.1073/pnas.0509228103] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nod1, a cytosolic protein that senses meso-diaminopimelic acid-containing ligands derived from peptidoglycan, plays a role in host responses to invasive bacteria. Here we describe a function for Nod1, whereby it controls tumor formation. Cell lines derived from the human breast cancer epithelial cell line MCF-7 were used in a severe combined immune deficiency (SCID) mouse xenograft model to characterize a pathway linking Nod1 to the growth of estrogen-sensitive tumors. In MCF-7 cells, the absence of Nod1 correlates with tumor growth, an increased sensitivity to estrogen-induced cell proliferation, and a failure to undergo Nod1-dependent apoptosis. Conversely, overexpression of Nod1 in MCF-7 cells results in inhibition of estrogen-dependent tumor growth and reduction of estrogen-induced proliferative responses in vitro.
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Affiliation(s)
- Jean da Silva Correia
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - Yvonne Miranda
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - Nikki Austin-Brown
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - Jenny Hsu
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - John Mathison
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - Rong Xiang
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - Huamin Zhou
- School of Life Sciences, Xiamen University, Xiamen 361005, Fujian, China
| | - Qinxi Li
- School of Life Sciences, Xiamen University, Xiamen 361005, Fujian, China
| | - Jiahuai Han
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
| | - Richard J. Ulevitch
- *Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037; and
- To whom correspondence should be addressed. E-mail:
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60
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Wong CH, Cheng CY. Mitogen-activated protein kinases, adherens junction dynamics, and spermatogenesis: a review of recent data. Dev Biol 2005; 286:1-15. [PMID: 16153630 DOI: 10.1016/j.ydbio.2005.08.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 07/05/2005] [Accepted: 08/02/2005] [Indexed: 11/23/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) are important regulators of many cellular processes. In mammalian testes, these kinases are involved in controlling cell division, differentiation, survival and death, and are therefore critical to spermatogenesis. Recent studies have also illustrated their involvement in junction restructuring in the seminiferous epithelium, especially at the ectoplasmic specialization (ES), a testis-specific adherens junction (AJ) type. ES contributes to the adhesion between Sertoli cells at the blood-testis barrier, as well as between Sertoli and developing spermatids (step 9 and beyond) at the adluminal compartment. MAPKs regulate AJ dynamics in the testis via their effects on the turnover of junction-associated protein complexes, the production of proteases and protease inhibitors, and the cytoskeleton structure. In this review, roles of the three major MAPK members, namely extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK, in ES dynamics are critically discussed. An integrated model of how these three MAPKs regulate adhesion function in the seminiferous epithelium is also presented. This model will serve as the framework for future investigation in the field.
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Affiliation(s)
- Ching-Hang Wong
- Population Council, 1230 York Avenue, New York, NY 10021, USA
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61
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Kim JM, Jung HY, Lee JY, Youn J, Lee CH, Kim KH. Mitogen-activated protein kinase and activator protein-1 dependent signals are essential for Bacteroides fragilis enterotoxin-induced enteritis. Eur J Immunol 2005; 35:2648-57. [PMID: 16114110 DOI: 10.1002/eji.200526321] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The approximately 20-kDa heat-labile toxin produced by enterotoxigenic Bacteroides fragilis is known to be associated with the development of enteritis. However, the molecular mechanism involved is not yet fully understood. In this study, we assessed whether B. fragilis enterotoxin (BFT)-induced enteritis is related to mitogen-activated protein kinase (MAPK) signaling pathways. In human colon epithelial cells, BFT activated three major MAPK cascades. The activation of p38 was sustained for a relatively long period, while the stimulation of extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) was transient. BFT stimulation also activated AP-1 signals composed of c-Jun/c-Fos heterodimers. The p38 inhibitor SB203580 and the ERK inhibitor U0126 reduced not only AP-1 activity, but also decreased IL-8 and MCP-1 expression. In addition, the overexpression of superrepressors for c-Jun and Ras induced by BFT stimulation decreased the levels of IL-8 and MCP-1 production. Furthermore, SB203580 prevented BFT-induced colitis in the mouse ileum, as evidenced by significant decreases in villous destruction, neutrophil infiltration, and mucosal congestion. These results suggest that a pathway, including Ras, MAPK, and subsequent AP-1 activation, is required for IL-8 and MCP-1 expression in intestinal epithelial cells exposed to BFT, and can be involved in the development of enteritis.
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Affiliation(s)
- Jung Mogg Kim
- Department of Microbiology and Institute of Biomedical Science, Hanyang University College of Medicine, Seoul, Korea.
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62
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Hanaka H, Shimizu T, Izumi T. Stress-induced nuclear export of 5-lipoxygenase. Biochem Biophys Res Commun 2005; 338:111-6. [PMID: 16165096 DOI: 10.1016/j.bbrc.2005.09.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 08/25/2005] [Accepted: 09/01/2005] [Indexed: 11/30/2022]
Abstract
A key enzyme for leukotriene biosynthesis is 5-lipoxygenase (5-LO), which we found is exported from the nucleus when p38 MAPK is activated. CHO-K1 cells stably express green fluorescent protein-5-lipoxygenase fusion protein (GFP-5LO), which is located predominantly in the nucleus, and is exported by anisomycin, hydrogen peroxide, and sorbitol, with activation of p38 MAPK. SB203580, an inhibitor of p38 MAPK, and Leptomycin B, an inhibitor of the nuclear export, blocked the anisomycin-induced export of GFP-5LO. When HEK293 cells were transformed with plasmids for wild-type GFP-5LO, GFP-5LO-S271A or GFP-5LO-S271E mutants, most wild-type GFP-5LO and GFP-5LO-S271A localized in the nucleus, but GFP-5LO-S271E localized in the cytosol. Thus, phosphorylation at Ser-271 of 5-LO is important for its export. Endogenous 5-LO in RBL cells stimulated with anisomycin was also exported from the nucleus. These results suggest that the nuclear export of 5-LO depends on the stress-induced activation of the p38 MAPK pathway.
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Affiliation(s)
- Hiromi Hanaka
- Department of Molecular Biochemistry, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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63
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Lee KH, Nishimura S, Matsunaga S, Fusetani N, Horinouchi S, Yoshida M. Inhibition of protein synthesis and activation of stress-activated protein kinases by onnamide A and theopederin B, antitumor marine natural products. Cancer Sci 2005; 96:357-64. [PMID: 15958059 PMCID: PMC11158271 DOI: 10.1111/j.1349-7006.2005.00055.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
During the course of screening for the agents that activate transforming growth factor-beta (TGF-beta) signaling cascade, onnamide A and theopederin B, heterocyclic compounds related to mycalamides from a marine sponge, were found to induce plasminogen activator inhibitor-1 (PAI-1) promoter-derived gene expression in Mv1Lu cells. The maximum induction of the PAI-1 promoter by onnamide A and theopederin B was observed at the concentrations of 50 nM and 2 nM, respectively. These compounds strongly inhibited protein synthesis at the 50% inhibitory concentrations of 30 nM for onnamide A and 1.9 nM for theopederin B, and induced activation of p38 mitogen-activated protein kinase and c-Jun NH2-terminal protein kinase (JNK). Anisomycin, a well-known inducer of ribotoxic stress that inhibits protein synthesis and activates both p38 kinase and JNK, also activated PAI-1 gene expression. Furthermore, PAI-1 expression by onnamide A, theopederin B, and anisomycin was inhibited by SB202190 and SP600125, specific inhibitors of stress-activated protein kinases. Onnamide A and theopederin B were cytotoxic to a variety of cell lines and strongly induced apoptosis in HeLa cells within 24 h, which was accompanied by the sustained activation of p38 kinase and JNK. These results suggest that onnamide A and theopedirin B trigger a ribotoxic stress-like response, thereby inducing p38 kinase and JNK activation, the kinase-dependent PAI-1 gene expression, and apoptosis.
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Affiliation(s)
- Kun-Hyung Lee
- Department of Biotechnology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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64
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Lindqvist A, Källström H, Karlsson Rosenthal C. Characterisation of Cdc25B localisation and nuclear export during the cell cycle and in response to stress. J Cell Sci 2005; 117:4979-90. [PMID: 15456846 DOI: 10.1242/jcs.01395] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cdc25 phosphatases are essential regulators of the cell cycle. In mammalian cells, the Cdc25B isoform activates cyclin A- and cyclin B1-containing complexes and is necessary for entry into mitosis. In this report, we characterise the subcellular localisation of Cdc25B by immunofluorescence in combination with RNA interference to identify specific antibody staining. We find that endogenous Cdc25B is mainly nuclear, but a fraction resides in the cytoplasm during the G2 phase of the cell cycle. Cdc25B starts to appear in S-phase cells and accumulates until prophase, after which the protein disappears. We characterise a nuclear export sequence in the N-terminus of Cdc25B (amino acids 54-67) that, when mutated, greatly reduces the ability of Cdc25B to shuttle in a fluorescence loss in photobleaching assay. Mutation of the nuclear export sequence makes Cdc25B less efficient in inducing mitosis, suggesting that an important mitotic function of Cdc25B occurs in the cytoplasm. Furthermore, we find that when cells are exposed to cycloheximide or ultraviolet irradiation, Cdc25B partially translocates to the cytoplasm. The dependence of this translocation event on a functional nuclear export sequence, an intact serine 323 residue (a 14-3-3 binding site) and p38 mitogen-activated protein kinase activity indicates that the p38 pathway regulates Cdc25B localisation in different situations of cellular stress.
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Affiliation(s)
- Arne Lindqvist
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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65
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Molnarfi N, Hyka-Nouspikel N, Gruaz L, Dayer JM, Burger D. The production of IL-1 receptor antagonist in IFN-beta-stimulated human monocytes depends on the activation of phosphatidylinositol 3-kinase but not of STAT1. THE JOURNAL OF IMMUNOLOGY 2005; 174:2974-80. [PMID: 15728510 DOI: 10.4049/jimmunol.174.5.2974] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
IFN-beta induces the production of secreted IL-1R antagonist (sIL-1Ra) without triggering synthesis of the agonist IL-1beta in human monocytes. This might account for its anti-inflammatory properties. Canonically, IFN-beta signals through activation of JAK/STAT pathway, although PI3K and MAPK have also been involved. In this study, the role of PI3K, MEK1, and STAT1 in IFN-beta-induced sIL-1Ra production is investigated in freshly isolated human blood monocytes. PI3K, but not MEK1 activation is essential for sIL-1Ra production in monocytes treated with IFN-beta, as demonstrated by using the respective inhibitors of PI3K and MEK1, Ly294002 and PD98059. The use of cycloheximide and actinomycin D shows that sIL-1Ra was an immediate early gene induced by IFN-beta and that PI3K was controlling sIL-1Ra gene transcription. Although both inhibitors of PI3K and MEK1 diminished the Ser(727) phosphorylation of STAT1 induced by IFN-beta, only Ly294002 inhibited sIL-1Ra production. Furthermore, the inhibition of STAT1-Ser(727) phosphorylation by Ly294002 did not affect STAT1 translocation, suggesting that STAT1 was not involved in sIL-1Ra gene induction. This was confirmed in monocytes that were transfected with small interfering RNA specifically targeting STAT1. Indeed, monocytes in which effective STAT1 gene knockdown was achieved were fully responsive to IFN-beta in terms of sIL-1Ra production. Taken together, the present data demonstrate that the induction of sIL-1Ra transcription and production by IFN-beta in human monocytes involved PI3K, but not STAT1 activation.
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Affiliation(s)
- Nicolas Molnarfi
- Division of Immunology and Allergy, Clinical Immunology Unit, Faculty of Medicine, University Hospital, Geneva, Switzerland
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Geiger PC, Wright DC, Han DH, Holloszy JO. Activation of p38 MAP kinase enhances sensitivity of muscle glucose transport to insulin. Am J Physiol Endocrinol Metab 2005; 288:E782-8. [PMID: 15585585 DOI: 10.1152/ajpendo.00477.2004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Muscle contractile activity is followed by an increase in the sensitivity of glucose transport to insulin. There is evidence suggesting that activation of p38 MAP kinase (p38) is involved in the stimulation of glucose transport by insulin and contractions. Exercise results in an increase in p38 phosphorylation that lasts for hours. In this context, we tested the hypothesis that activation of p38 results in an increase in insulin sensitivity. Muscles were exposed to anisomycin for 30 min to activate p38. Anisomycin increased p38 phosphorylation approximately 2.5-fold and glucose transport activity 2- to 3-fold. Three hours after anisomycin treatment, by which time the acute effect on glucose transport had partially worn off, sensitivity of muscle glucose transport to 60 microU/ml insulin was markedly increased. Both the activation of p38 and the increase in insulin sensitivity induced by anisomycin were completely prevented by pretreatment of muscles with the p38 inhibitor SB-202190. However, in contrast to the finding with anisomycin, inhibition of p38 activation did not prevent the contraction-induced increase in insulin sensitivity. Thus our results show that activation of p38 is followed by an increase in insulin sensitivity of muscle glucose transport. However, activation of p38 is not necessary for induction of an increase in muscle insulin sensitivity by contractions. This finding provides evidence that contractions have an additional effect that makes p38 activation unnecessary for enhancement of insulin sensitivity by contractile activity.
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Affiliation(s)
- Paige C Geiger
- Departemnt of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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67
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Matsui JI, Gale JE, Warchol ME. Critical signaling events during the aminoglycoside-induced death of sensory hair cells in vitro. ACTA ACUST UNITED AC 2005; 61:250-66. [PMID: 15389694 DOI: 10.1002/neu.20054] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sensory hair cells undergo apoptosis following exposure to aminoglycoside antibiotics. In neurons, apoptosis is associated with a transient increase in intracellular Ca2+, phosphorylation of the transcription factor c-Jun, and the release of cytochrome c from mitochondria into the cytosol, which along with other cofactors results in the activation of caspases. To examine the possible role of these events in the survival and death of the sensory receptors of the inner ear, we examined the effects of neomycin treatment on cytoplasmic calcium, activation of c-Jun-N-Terminal kinases (JNKs), cytochrome c release, and caspase-3 activation in cultured vestibular hair cells. Increased numbers of phospho-c-Jun-labeled hair cells (a downstream indicator of JNK activation) were observed at 3-12 h after neomycin treatment, whereas increased numbers of cells with cytoplasmic cytochrome c were observed at 12-18 h following the onset of neomycin treatment. This was followed by an increase in the number of cells that contained activated caspase-3 and displayed pyknotic nuclei. Treatment with the general caspase inhibitor BAF did not affect the release of cytochrome c and the number of p-c-Jun-labeled cells, but reduced the number of cells with activated caspase-3 and pyknotic nuclei. In contrast, treatment with CEP-11004, an indirect inhibitor of the JNK signaling pathway, promoted hair cell survival following neomycin treatment and reduced the number of cells with phosphorylated JNK and c-Jun, cytoplasmic cytochrome c, and activated caspase 3. These results suggest that JNK activation occurs upstream of the release of cytochrome c and that cytochrome c release precedes caspase activation. Cytochrome c release and JNK activation were also preceded by large changes in cytoplasmic calcium. Cytoplasmic calcium increases may be causally related to the release of cytochrome c, and may also be a potential pathway for activation of JNK in hair cells.
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Affiliation(s)
- Jonathan I Matsui
- Division of Biology and Biomedical Sciences, Program in Neurosciences, Washington University, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
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68
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Wang MM, Tu E, Raymond DE, Yang JM, Zhang H, Hagen N, Dees B, Mercer EM, Forster AH, Kariv I, Marchand PJ, Butler WF. Microfluidic sorting of mammalian cells by optical force switching. Nat Biotechnol 2005; 23:83-7. [PMID: 15608628 DOI: 10.1038/nbt1050] [Citation(s) in RCA: 537] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Accepted: 10/22/2004] [Indexed: 11/08/2022]
Abstract
Microfluidic-based devices have allowed miniaturization and increased parallelism of many common functions in biological assays; however, development of a practical technology for microfluidic-based fluorescence-activated cell sorting has proved challenging. Although a variety of different physical on-chip switch mechanisms have been proposed, none has satisfied simultaneously the requirements of high throughput, purity, and recovery of live, unstressed mammalian cells. Here we show that optical forces can be used for the rapid (2-4 ms), active control of cell routing on a microfluidic chip. Optical switch controls reduce the complexity of the chip and simplify connectivity. Using all-optical switching, we have implemented a fluorescence-activated microfluidic cell sorter and evaluated its performance on live, stably transfected HeLa cells expressing a fused histone-green fluorescent protein. Recovered populations were verified to be both viable and unstressed by evaluation of the transcriptional expression of two genes, HSPA6 and FOS, known indicators of cellular stress.
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Affiliation(s)
- Mark M Wang
- Genoptix, Inc., 3398 Carmel Mountain Road, San Diego, California 92121, USA
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69
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Duvarci S, Nader K, LeDoux JE. Activation of extracellular signal-regulated kinase- mitogen-activated protein kinase cascade in the amygdala is required for memory reconsolidation of auditory fear conditioning. Eur J Neurosci 2005; 21:283-9. [PMID: 15654867 DOI: 10.1111/j.1460-9568.2004.03824.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Consolidation of new fear memories has been shown to require de novo RNA and protein synthesis in the lateral nucleus of amygdala (LA). Recently we have demonstrated that consolidated fear memories, when reactivated, return to a labile state which is sensitive to disruption by the protein synthesis inhibitor anisomycin. The specific molecular mechanisms that underlie this reconsolidation of fear memories are still largely unknown. The activation of extracellular signal-regulated kinase-mitogen-activated protein kinase (ERK-MAPK) pathway in the LA is required for the consolidation of auditory fear memories. In the present study, we examined the role of ERK-MAPK cascade in the LA during reconsolidation of auditory fear conditioning. We show that intra-LA infusions of the MAPK kinase (MEK) inhibitor U0126, a manipulation which inhibits activation of ERK-MAPK, impairs postreactivation long-term memory (PR-LTM) but leaves the postreactivation short-term memory (PR-STM) intact. The same treatment with U0126, in the absence of memory reactivation, has no effect. Furthermore, we verified that reconsolidation requires translation using a second protein synthesis inhibitor, cycloheximide. Post-reactivation infusions of cycloheximide blocked PR-LTM but not PR-STM and, in the absence of reactivation, had no effect. Our data show that activation of ERK-MAPK signalling pathway and protein synthesis in the LA are required for reconsolidation of auditory fear memories.
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Affiliation(s)
- Sevil Duvarci
- W.M. Keck Foundation Laboratory of Neurobiology, Center for Neural Science, New York University, NY, USA
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70
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Abstract
Long term potentiation (LTP) at hippocampal Schaffer collateral-CA1 synapses involves an early and a late phase, where only the latter is sensitive to protein synthesis inhibitors. Here we characterized the dynamics of protein synthesis associated with the induction of L-LTP using a transgenic mouse model in which a cAMP responsive element (CRE)-regulated promoter drives production of an enhanced yellow fluorescent protein (eYFP). We found that eYFP fluorescence increased after less than 30 min following L-LTP induction. Application of transcription and translation suppressors and the NMDA receptor antagonist D-AP5 inhibited the L-LTP and prevented the rise in eYFP levels. The early-phase of LTP was not affected by inhibiting protein synthesis.
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Affiliation(s)
- Thomas Behnisch
- Laboratory for Neuronal Circuit Dynamics, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
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71
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Marverti G, Monti MG, Bettuzzi S, Caporali A, Astancolle S, Moruzzi MS. Cisplatin-resistance modulates the effect of protein synthesis inhibitors on spermidine/spermine N(1)-acetyltransferase expression. Int J Biochem Cell Biol 2004; 36:123-37. [PMID: 14592538 DOI: 10.1016/s1357-2725(03)00174-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cisplatin (DDP)-resistance confers a deficient expression of spermidine/spermine N(1)-acetyltransferase (SSAT) gene in response to the spermine analog N(1),N(12)-bis(ethyl)spermine (BESpm) in the DDP-resistant human ovarian carcinoma cell line (C13*), compared with their parental DDP-sensitive 2008 cells. This SSAT gene deficiency is correlated with a reduced growth sensitivity to spermine analogs. This study was performed to determine whether SSAT gene expression of resistant cells was kept suppressed by labile repressor proteins developed during resistance selection. We show here that inhibitory concentrations of cycloheximide (CHX) and anisomycin (ANISO) differentially affect BESpm-induced SSAT activity in 2008 and in C13* cells in a concentration-dependent manner and allow resistant cells to reach activation levels comparable to those of the sensitive cells. Northern blot analysis revealed that both CHX and ANISO in combination with BESpm caused a synergistic BESpm-mediated accumulation of SSAT mRNA in C13* cells, with respect to each drug alone, while in 2008 cells only a slight increase was observed. The more pronounced effect of inhibitors on the SSAT activity induced by BESpm in the resistant cells was also the result of a more prolonged stabilization of SSAT mRNA and enzyme protein. By contrast, sub-inhibitory concentrations of CHX and ANISO did not significantly stimulate BESpm-induced SSAT transcription and activity. These results suggest that labile repressor proteins, related to DDP-resistance phenotype, play a regulatory role in SSAT gene expression, and further indicate that by overcoming this inhibitory control it is possible to recover BESpm response.
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Affiliation(s)
- Gaetano Marverti
- Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Università di Modena e Reggio Emilia, Via Campi 287, 41100, Modena, Italy.
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72
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Sanfilippo CM, Lombardozzi RC, Chirimuuta FNW, Blaho JA. Herpes simplex virus 1 infection is required to produce ICP27 immunoreactive triplet forms when ribosomal aminoacyl-tRNA translocation is blocked by cycloheximide. Virology 2004; 324:554-66. [PMID: 15207640 DOI: 10.1016/j.virol.2004.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Revised: 03/11/2004] [Accepted: 04/09/2004] [Indexed: 10/26/2022]
Abstract
Infected cell protein (ICP) 27 is an essential herpes simplex virus type 1 (HSV-1) phosphoprotein required for optimal viral DNA and early or late gene synthesis. Three slow-migrating immunoreactive species were detected using multiple anti-ICP27 antibodies following HSV-1 infection of HEp-2 and Vero cells in the presence of cycloheximide (CHX). Generation of the protein triplet moieties required transcription of the alpha27 gene. These forms were observed following infection with a series of recombinant viruses that produce truncated ICP27 polypeptides, suggesting that alternative splicing is not involved in the process. These ICP27 species were not observed following translation inhibition by puromycin (PUR). Synthesis of the triplet occurred by 6 hpi and CHX addition as late as 3 hpi still enabled their production. That the ICP27 species were detected in uninfected ICP27-expressing cells without CHX, but not in its presence, suggests a mechanism in which virus infection is required to produce the forms when ribosomal aminoacyl-transfer RNA (tRNA) translocation is blocked.
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Affiliation(s)
- Christine M Sanfilippo
- Department of Microbiology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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73
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Konishi Y, Sato H, Tanaka T. Anisomycin superinduces annexin V mRNA expression through the ERK1/2 but not the p38 MAP kinase pathway. Biochem Biophys Res Commun 2004; 313:977-83. [PMID: 14706638 DOI: 10.1016/j.bbrc.2003.12.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Annexin V is a Ca(2+)-dependent phospholipid-binding protein belonging to the annexin family whose regulation is currently not well understood. In this study, we utilized anisomycin, a protein synthesis inhibitor that activates MAP kinases (MAPKs), to examine the role of MAPKs in annexin V expression in the MCAS ovarian carcinoma cell line. A one-step real-time TaqMan-based reverse transcriptase-PCR method was developed to quantify annexin V mRNA expression. We found that annexin V was induced 13.3-fold by anisomycin and that this superinduction was attenuated by pretreatment with the MEK inhibitors, U0126 and PD98059, but not with the p38 MAPK inhibitor, SB203580. In addition, immunoblotting showed that anisomycin stimulated the phosphorylation of ERK1/2 as well as p38 MAPK and that the phosphorylations were blocked by the three kinase inhibitors. Taken together, these results suggest that anisomycin superinduces annexin V mRNA expression through the ERK1/2 MAPK pathway, but not through the p38 MAPK pathway.
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Affiliation(s)
- Yoshitomo Konishi
- Department of Obstetrics and Gynecology, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan
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74
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Helicobacter pylori in a Korean isolate activates mitogen-activated protein kinases, AP-1, and NF-kappaB and induces chemokine expression in gastric epithelial AGS cells. J Transl Med 2004. [PMID: 14631383 DOI: 10.1038/labinvest.3700010] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Oxidant-sensitive transcription factors, nuclear factor-kappaB (NF-kappaB), and activator protein-1 (AP-1) have been considered as the regulators of inducible genes such as chemokines. Since oxygen radicals are considered as an important regulator in the pathogenesis of Helicobacter pylori (H. pylori)-induced gastric ulceration and carcinogenesis, chemokines such as interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) may be regulated by NF-kappaB and/or AP-1. Ras, the upstream activator for mitogen-activated protein kinase (MAPK) and MAPK cascade regulate AP-1 activation. The present study aims to investigate whether H. pylori in a Korean isolate (HP99) induces the expression of chemokines (IL-8, MCP-1), which is regulated by Ras, MAPK, AP-1, and NF-kappaB in gastric epithelial AGS cells, and whether these transcriptional regulations of chemokines are inhibited by transfection with mutant genes for Ras (ras N-17), c-Jun (TAM-67), and IkappaBalpha (MAD-3) or treatment with MAPK inhibitors (U0126 for extracellular signal-regulated kinase or SB203580 for p38 kinase). In addition, virulence factors of HP99 were characterized by PCR analysis for the isolated DNA. As a result, HP99 is identified as cagA+, vacA s1b, m2, iceA1 H. pylori strain. HP99 induced a time-dependent expression of mRNA and protein for IL-8 and MCP-1 via mediation of MAPK, AP-1, and NF-kappaB. Transfection with mutant genes for Ras, c-Jun, and IkappaBalpha and treatment with MAPK inhibitors suppressed H. pylori-induced activation of transcription factors (NF-kappaB, AP-1) and expression of chemokines (IL-8, MCP-1) in AGS cells. In conclusion, Ras and MAPK cascade may act as the upstream signaling for the activation of AP-1 and NF-kappaB, which induce chemokine expression in H. pylori-infected AGS cells. Specific targeting of the activation of NF-kappaB and AP-1 may be effective for the prevention or treatment of gastric inflammation associated with H. pylori infection.
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75
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Cunningham O, Andolfo A, Santovito ML, Iuzzolino L, Blasi F, Sidenius N. Dimerization controls the lipid raft partitioning of uPAR/CD87 and regulates its biological functions. EMBO J 2004; 22:5994-6003. [PMID: 14609946 PMCID: PMC275445 DOI: 10.1093/emboj/cdg588] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The urokinase-type plasminogen activator receptor (uPAR/CD87) is a glycosylphosphatidylinositol-anchored membrane protein with multiple functions in extracellular proteolysis, cell adhesion, cell migration and proliferation. We now report that cell surface uPAR dimerizes and that dimeric uPAR partitions preferentially to detergent-resistant lipid rafts. Dimerization of uPAR did not require raft partitioning as the lowering of membrane cholesterol failed to reduce dimerization and as a transmembrane uPAR chimera, which does not partition to lipid rafts, also dimerized efficiently. While uPA bound to uPAR independently of its membrane localization and dimerization status, uPA-induced uPAR cleavage was strongly accelerated in lipid rafts. In contrast to uPA, the binding of Vn occurred preferentially to raft- associated dimeric uPAR and was completely blocked by cholesterol depletion.
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Affiliation(s)
- Orla Cunningham
- Molecular Genetics Unit, Department of Molecular Biology and Functional Genomics, Università Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milan, Italy
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76
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77
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Choi KH, Choi HY, Ko JK, Park SS, Kim YN, Kim CW. Transcriptional regulation of TNF family receptors and Bcl-2 family by chemotherapeutic agents in murine CT26 cells. J Cell Biochem 2004; 91:410-22. [PMID: 14743399 DOI: 10.1002/jcb.10745] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Various chemotherapeutic agents have been shown to sensitize cancer cells to members of the tumor necrosis factor (TNF) family. However, it is unclear whether sensitization by chemotherapeutic agents involves the transcriptional regulation of apoptosis-related genes. In this study, we investigated mRNA regulation of TNF family receptors and Bcl-2 family members after treating the murine colon cancer cell line, CT26, with various apoptosis inducers. We found that treatment with cycloheximide, a protein synthesis inhibitor, remarkably increased CD40 mRNA levels by semi-quantitative RT-PCR. Other protein synthesis inhibitors, such as anisomycin and emetine, also enhanced CD40 mRNA expression, which was significantly blocked by a NF-kappaB antagonist and a p38 MAP kinase antagonist. After treatment with cycloheximide, and further cultivation in fresh medium, CD40 protein levels were found to increase by flow cytometry. Additionally, we found that cycloheximide treatment appeared to downregulate the Bcl-xL mRNA level but not the Bax mRNA level by RNase protection assay. Because the upregulation of CD40 mRNA and the downregulation of Bcl-xL correlated with CT26 cell death, our results suggest that chemotherapeutic agents, including cycloheximide, may exert their synergistic effects on the TNF family treatment of cancer cells by regulating the mRNA levels of apoptosis-related genes.
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Affiliation(s)
- Kyoung-Han Choi
- Department of Pathology, Tumor Immunity Medical Research Center and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
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78
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Uzarski RL, Pestka JJ. Comparative susceptibility of B cells with different lineages to cytotoxicity and apoptosis induction by translational inhibitors. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2003; 66:2105-2118. [PMID: 14710595 DOI: 10.1080/15287390390211315] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The trichothecene mycotoxins, Shiga toxins (STs), and ricin are potent translational inhibitors that exert diverse mechanisms of action but all have the capacity to induce death by apoptosis. Germinal centers containing actively dividing B cells are particularly sensitive to protein synthesis inhibition, and, of these, the immature B cell is reportedly most susceptible to apoptosis. The objective of this study was to test the hypothesis that immature and mature B-cell lineages were differentially susceptible to apoptosis and cytotoxicity induction by representative trichothecene mycotoxins, ST-1, and ricin, as well as cycloheximide (CHX), a prototypical protein synthesis inhibitor commonly used to study cell signal transduction. WEHI-231 and CH31 cells were used as representatives of phenotypically immature B cells, whereas CH12.LX cells were used to model mature B cells. Resultant data suggest that Type D and Type A trichothecenes, ricin, and ST-1 were more potent inducers of apoptosis than CHX, whereas Type B and Type A trichothecene metabolites were less. CHX and the trichothecenes affected immature and mature B cells equally, thus suggesting that toxicity due to these natural toxins was lineage independent. In contrast, mature B cells were more sensitive to ricin- and ST-1-induced cytotoxicity and apoptosis than immature B cells. Taken together, these results suggest that B cells are targets of a diverse array of naturally occurring translational inhibitors. Upregulation of apoptosis in B lymphocytes may contribute to the impairment of the immune response and other symptoms described following exposure to these toxins.
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Affiliation(s)
- Rebecca L Uzarski
- Department of Food Science and Human Nutrition, Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824-1224, USA
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79
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Holzberg D, Knight CG, Dittrich-Breiholz O, Schneider H, Dörrie A, Hoffmann E, Resch K, Kracht M. Disruption of the c-JUN-JNK complex by a cell-permeable peptide containing the c-JUN delta domain induces apoptosis and affects a distinct set of interleukin-1-induced inflammatory genes. J Biol Chem 2003; 278:40213-23. [PMID: 12832416 DOI: 10.1074/jbc.m304058200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcription factor activator protein (AP)-1 plays crucial roles in proliferation, cell death, and the immune response. c-JUN is an important component of AP-1, but only very few c-JUN response genes have been identified to date. Activity of c-JUN is controlled by NH2-terminal phosphorylation (JNP) of its transactivation domain by a family of JUN-NH2-terminal protein kinases (JNK). JNK form a stable complex with c-JUN in vitro and in vivo. We have targeted this interaction by means of a cell-permeable peptide containing the JNK-binding (delta) domain of human c-JUN. This peptide strongly and specifically induced apoptosis in HeLa tumor cells, which was paralleled by inhibition of serum-induced c-JUN phosphorylation and up-regulation of the cell cycle inhibitor p21cip/waf. Application of the c-JUN peptide to interleukin (IL)-1-stimulated human primary fibroblasts resulted in up-regulation of four genes, namely COX-2, MnSOD, I kappa B alpha, and MAIL and down-regulation of 10 genes, namely CCL8, mPGES, SAA1, hIAP-1, hIAP-2, pent(r)axin-3, CXCL10, IL-1 beta, ICAM-1, and CCL2. Only a small group of genes, namely pent(r)axin-3, CXCL10, ICAM-1, and IL-1 beta, was inhibited by both the c-JUN peptide and the JNK inhibitor SP600125. Thereby, and by additional experiments using small interfering RNA to suppress endogenous c-JUN we identify for the first time three distinct groups of inflammatory genes whose IL-1-induced expression depends on c-JUN, on JNK, or on both. These results shed further light on the complexity of c-JUN-JNK-mediated gene regulation and also highlight the potential use of dissecting signaling downstream from JNK to specifically target proliferative diseases or the inflammatory response.
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Affiliation(s)
- David Holzberg
- Institute of Pharmacology, Medical School Hannover, Carl-Neuberg Strasse 1, D-30625 Hannover, Germany
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80
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Kiehl A, Huang L, Franchi D, Anders DG. Multiple 5′ ends of human cytomegalovirus UL57 transcripts identify a complex, cycloheximide-resistant promoter region that activates oriLyt. Virology 2003; 314:410-22. [PMID: 14517093 DOI: 10.1016/s0042-6822(03)00438-0] [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: 11/28/2022]
Abstract
The human cytomegalovirus (HCMV) UL57 gene lies adjacent to HCMV oriLyt, from which it is separated by an organizationally conserved, mostly noncoding region that is thought to both regulate UL57 expression and activate oriLyt function. However, the UL57 promoter has not been studied. We determined the 5' ends of UL57 transcripts toward an understanding of the potential relationship between UL57 expression and oriLyt activation. The results presented here identified three distinct 5' ends spread over 800 bp, at nt 90302, 90530, and 91138; use of these sites exhibited differential sensitivity to phosphonoformic acid treatment. Interestingly, a 10-kb UL57 transcript accumulated in cycloheximide-treated infected cells, even though other early transcripts were not detectable. However, the 10-kb transcript did not accumulate in cells treated with the more stringent translation inhibitor anisomycin. Consistent with the notion that the identified 5' ends arise from distinct transcription start sites, the sequences upstream of sites I and II functioned as promoters responsive to HCMV infection in transient assays. However, the origin-proximal promoter region III required downstream sequences for transcriptional activity. Mutation of candidate core promoter elements suggested that promoter III is regulated by an initiator region (Inr) and a downstream promoter element. Finally, a 42-bp sequence containing the candidate Inr activated a minimal oriLyt core construct in transient replication assays. Thus, these studies showed that a large, complex promoter region with novel features controls UL57 expression, and identified a sequence that regulates both UL57 transcription and oriLyt activation.
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Affiliation(s)
- Anita Kiehl
- The David Axelrod Institute, Wadsworth Center, NYSDOH, P.O. Box 22002, Albany, NY 12201-2002, USA
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81
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Shaw PE, Saxton J. Ternary complex factors: prime nuclear targets for mitogen-activated protein kinases. Int J Biochem Cell Biol 2003; 35:1210-26. [PMID: 12757758 DOI: 10.1016/s1357-2725(03)00031-1] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Ternary complex factors (TCFs), a subgroup of the ETS protein family, were first described in the context of c-fos gene regulation. Subsequently, their early identification as nuclear targets for mitogen-activated protein kinases served to exemplify the fundamental links in eukaryotic cells between growth factor-mediated signalling pathways and gene control. This article provides an overview of recent work on ternary complex factors, addressing their expression and molecular structure, as well as how selective interactions with members of other protein families serve to up-1 regulate or restrict their activity. Although only one genetic study on ternary complex factors has been published to date, unravelling of the underlying molecular events provides a basis for tentative predictions about their biological roles in mammalian organisms.
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Affiliation(s)
- Peter E Shaw
- Queen's Medical Centre, School of Biomedical Sciences, University of Nottingham, UK.
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82
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Beugnet A, Tee AR, Taylor PM, Proud CG. Regulation of targets of mTOR (mammalian target of rapamycin) signalling by intracellular amino acid availability. Biochem J 2003; 372:555-66. [PMID: 12611592 PMCID: PMC1223408 DOI: 10.1042/bj20021266] [Citation(s) in RCA: 236] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2002] [Revised: 02/07/2003] [Accepted: 02/28/2003] [Indexed: 11/17/2022]
Abstract
In mammalian cells, amino acids affect the phosphorylation state and function of several proteins involved in mRNA translation that are regulated via the rapamycin-sensitive mTOR (mammalian target of rapamycin) pathway. These include ribosomal protein S6 kinase, S6K1, and eukaryotic initiation factor 4E-binding protein, 4E-BP1. Amino acids, especially branched-chain amino acids, such as leucine, promote phosphorylation of 4E-BP1 and S6K1, and permit insulin to further increase their phosphorylation. However, it is not clear whether these effects are exerted by extracellular or intracellular amino acids. Inhibition of protein synthesis is expected to increase the intracellular level of amino acids, whereas inhibiting proteolysis has the opposite effect. We show in the present study that inhibition of protein synthesis by any of several protein synthesis inhibitors tested allows insulin to regulate 4E-BP1 or S6K1 in amino-acid-deprived cells, as does the addition of amino acids to the medium. In particular, insulin activates S6K1 and promotes initiation factor complex assembly in amino-acid-deprived cells treated with protein synthesis inhibitors, but cannot do so in the absence of these compounds. Their effects occur at concentrations commensurate with their inhibition of protein synthesis and are not due to activation of stress-activated kinase cascades. Inhibition of protein breakdown (autophagy) impairs the ability of insulin to regulate 4E-BP1 or S6K1 under such conditions. These and other data presented in the current study are consistent with the idea that it is intracellular amino acid levels that regulate mTOR signalling.
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Affiliation(s)
- Anne Beugnet
- School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Scotland, UK
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83
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Ahmed T, Frey JU. Expression of the specific type IV phosphodiesterase gene PDE4B3 during different phases of long-term potentiation in single hippocampal slices of rats in vitro. Neuroscience 2003; 117:627-38. [PMID: 12617967 DOI: 10.1016/s0306-4522(02)00838-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Hippocampal long-term potentiation (LTP), the most prominent cellular model for learning and memory formation, consists of phases: early-LTP (<4 h) and late-LTP (>4 h), with the latter dependent upon protein translation and transcription. To explore the molecular processes that might be specifically regulated during late-LTP, we have modified standard electrophysiological and molecular biological methods, which allowed the cloning of activated genes and their products from single hippocampal slices in vitro 8 h after LTP induction. From one such screen we identified a specific type IV phosphodiesterase gene, PDE4B3, the first cAMP-specific phosphodiesterase to be associated with LTP. Previous studies documented an integral role for the cAMP-PKA system in late-LTP and recently, inhibition of cAMP degradation facilitates LTP and ameliorates mnemonic deficits. We now report that PDE4B3 is modulated during LTP phases. Its activation is NMDA-receptor dependent and its transcription is transiently up-regulated 2 h after tetanization. Protein expression peaks 6 h after LTP induction and is rapidly down-regulated at 8 h, whereas cAMP levels decrease during LTP phases. Immunohistochemical studies identified that the majority of type IV phosphodiesterase protein staining is localized to the cell bodies and dendrites of neurones in hippocampal CA1.
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MESH Headings
- 3',5'-Cyclic-AMP Phosphodiesterases/classification
- 3',5'-Cyclic-AMP Phosphodiesterases/genetics
- 3',5'-Cyclic-AMP Phosphodiesterases/physiology
- Animals
- Animals, Newborn
- Bacterial Proteins/metabolism
- Blotting, Northern/methods
- Blotting, Western/methods
- Cyclic Nucleotide Phosphodiesterases, Type 4
- Electric Stimulation/methods
- Electrophysiology
- Gene Expression/drug effects
- Gene Expression/physiology
- Hemolysin Proteins
- Hippocampus/drug effects
- Hippocampus/physiology
- In Vitro Techniques
- Long-Term Potentiation/genetics
- Long-Term Potentiation/physiology
- Male
- Neurofilament Proteins/metabolism
- Neurons/physiology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Wistar
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Time Factors
- Valine/analogs & derivatives
- Valine/pharmacology
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Affiliation(s)
- T Ahmed
- Leibniz-Institute for Neurobiology, Department of Neurophysiology, Brenneckestrasse 6, Postfach 1860, D-39008, Magdeburg, Germany.
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84
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Mao L, Wang JQ. Metabotropic glutamate receptor 5-regulated Elk-1 phosphorylation and immediate early gene expression in striatal neurons. J Neurochem 2003; 85:1006-17. [PMID: 12716432 DOI: 10.1046/j.1471-4159.2003.01750.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Galphaq protein-coupled metabotropic glutamate receptor subtype-5 (mGluR5) is densely expressed in medium spiny projection neurons of striatum. Emerging evidence suggests a significant role of mGluR5 in the addictive plasticity of striatal neurons that is likely derived from inducible cellular gene expression related to stimulation of mGluR5 and associative signaling proteins. In this study, we found that activation of mGluR5 with a selective agonist (RS)-2-chloro-5-hydroxy-phenylglycine (CHPG) induced a rapid and transient phosphorylation of a transcription regulator Elk-1 in cultured striatal neurons from rat E19 embryos or neonatal day-1 pups. The Elk-1 phosphorylation was dose-dependent and occurred in neurochemically identified GABAergic neurons, but not glia. A series of experiments further demonstrated that the CHPG-stimulated Elk-1 phosphorylation was mediated through selective activation of mGluR5-regulated phospholipase C and associative second messenger system, i.e. 1,4,5,-triphosphate-sensitive Ca2+ release. Moreover, the Elk-1 phosphorylation was partially dependent on mGluR5-mediated co-activation of NMDA, but not kainate/AMPA receptors and L-type voltage-operated Ca2+ channels. Using an immediate early gene c-fos as a report of inducible gene expression, we found that CHPG induced marked c-fos mRNA expression. The c-fos induction kinetically corresponded to the Elk-1 phosphorylation and was attenuated by antisense oligonucleotides that selectively knocked down Elk-1 proteins. These results indicate that glutamatergic tone on mGluR5 is positively coupled to Elk-1 phosphorylation in striatal neurons via multiple signaling mechanisms involving Ca2+ release and NMDA activation, and the mGluR5-mediated Elk-1 phosphorylation facilitates gene transcription.
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Affiliation(s)
- Limin Mao
- Department of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, 2411 Holmes Street, Rm. M3-C225, Kansas City, MO 64108, USA
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85
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Itani OA, Cornish KL, Liu KZ, Thomas CP. Cycloheximide increases glucocorticoid-stimulated alpha -ENaC mRNA in collecting duct cells by p38 MAPK-dependent pathway. Am J Physiol Renal Physiol 2003; 284:F778-87. [PMID: 12505861 DOI: 10.1152/ajprenal.00088.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aldosterone and glucocorticoids (GCs) stimulate Na(+) reabsorption in the collecting ducts by increasing the activity of the epithelial Na(+) channel (ENaC). Our laboratory has used Madin-Darby canine kidney-C7 cells to demonstrate that this effect is associated with an increase in alpha-ENaC gene transcription (Mick VE, Itani OA, Loftus RW, Husted RF, Schmidt TJ, and Thomas CP, Mol Endocrinol 15: 575-588, 2001). Cycloheximide (CHX) superinduced the GC-stimulated alpha-ENaC expression in a dose-dependent manner, but had no effect on basal or aldosterone-stimulated alpha-ENaC expression, whereas anisomycin inhibited basal and corticosteroid-stimulated alpha-ENaC expression. The superinduction of alpha-ENaC expression was also seen with hypotonicity, was blocked by RU-38486, and was independent of protein synthesis. CHX had no effect on alpha-ENaC mRNA half-life, confirming that its effect was via an increase in alpha-ENaC transcription. The effect of CHX and hypotonicity on alpha-ENaC expression was abolished by SB-202190, indicating an effect mediated via p38 MAPK. Consistent with this scheme, CHX increased pp38 and MKK6, an upstream activator of p38, stimulated alpha-ENaC promoter activity. These data confirm a model in which CHX activates p38 in Madin-Darby canine kidney-C7 cells to increase alpha-ENaC gene transcription in a GC-dependent manner.
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Affiliation(s)
- Omar A Itani
- Department of Internal Medicine, and Graduate Program in Molecular Biology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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86
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Bunyard P, Handley M, Pollara G, Rutault K, Wood I, Chaudry M, Alderman C, Foreman J, Katz DR, Chain BM. Ribotoxic stress activates p38 and JNK kinases and modulates the antigen-presenting activity of dendritic cells. Mol Immunol 2003; 39:815-27. [PMID: 12617997 DOI: 10.1016/s0161-5890(02)00262-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Initiation of adaptive immunity requires activation of dendritic cells (DC) by "danger" signals. This study examines the functional consequences of activating a cellular stress response in human DC. Anisomycin, a potent inducer of this "stress" response, selectively activates p38 kinase in DC at low concentrations, and both p38 kinases and JNKs at higher concentrations. Activation of p38, was accompanied by an increase in the potency of dendritic cells to activate T cells. In contrast to LPS, anisomycin had no effect on the expression of several DC activation markers. Anisomycin synergised with LPS in driving release of IL-12 and TNF-alpha. Anisomycin also enhanced the formation of clusters between DC and T cells. Enhanced cytokine release and clustering were both inhibited by the selective p38 alpha and p38 beta inhibitor SB203580. This study demonstrates that the cellular stress response, mediated via p38 kinases, plays an important role in the regulation of several aspects of DC function.
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Affiliation(s)
- Peter Bunyard
- Department of Immunology and Molecular Biology, Windeyer Institute for Medical Sciences, University College London, 46 Cleveland Street, London W1T 4JF, UK
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87
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Kerkeb L, Krämer U. The role of free histidine in xylem loading of nickel in Alyssum lesbiacum and Brassica juncea. PLANT PHYSIOLOGY 2003; 131:716-24. [PMID: 12586895 PMCID: PMC166847 DOI: 10.1104/pp102.010686] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2002] [Revised: 08/04/2002] [Accepted: 10/27/2002] [Indexed: 05/18/2023]
Abstract
Exposure of the hyperaccumulator Alyssum lesbiacum to nickel (Ni) is known to result in a dose-dependent increase in xylem sap concentrations of Ni and the chelator free histidine (His). Addition of equimolar concentrations of exogenous L-His to an Ni-amended hydroponic rooting medium enhances Ni flux into the xylem in the nonaccumulator Alyssum montanum, and, as reported here, in Brassica juncea L. cv Vitasso. In B. juncea, reducing the entry of L-His into the root by supplying D-His instead of L-His, or L-His in the presence of a 10-fold excess of L-alanine, did not affect root Ni uptake, but reduced Ni release into the xylem. Compared with B. juncea, root His concentrations were constitutively about 4.4-fold higher in A. lesbiacum, and did not increase within 9 h of exposure to Ni. Cycloheximide did not affect root His or Ni concentrations, but strongly decreased the release of His and Ni from the root into the xylem of A. lesbiacum, whereas xylem sap concentrations of Ca and Mg remained unaffected. Near-quantitative chelation of Ni with nitrilotriacetate in the rooting medium did not enhance Ni flux into the xylem of A. lesbiacum and B. juncea, suggesting the absence of a significant apoplastic pathway for Ni entry into the xylem. The data suggest that in B. juncea roots, Ni(2+) uptake is independent of simultaneous uptake of His. In both species, enhanced release of Ni into the xylem is associated with concurrent release of His from an increased root free His pool.
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Affiliation(s)
- Loubna Kerkeb
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Golm, Germany
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88
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Clerk A, Kemp TJ, Harrison JG, Mullen AJ, Barton PJR, Sugden PH. Up-regulation of c-jun mRNA in cardiac myocytes requires the extracellular signal-regulated kinase cascade, but c-Jun N-terminal kinases are required for efficient up-regulation of c-Jun protein. Biochem J 2002; 368:101-10. [PMID: 12169099 PMCID: PMC1222976 DOI: 10.1042/bj20021083] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2002] [Revised: 08/05/2002] [Accepted: 08/08/2002] [Indexed: 02/03/2023]
Abstract
Cardiac hypertrophy, an important adaptational response, is associated with up-regulation of the immediate early gene, c- jun, which encodes the c-Jun transcription factor. c-Jun may feed back to up-regulate its own transcription and, since the c-Jun N-terminal kinase (JNK) family of mitogen-activated protein kinases (MAPKs) phosphorylate c-Jun(Ser-63/73) to increase its transactivating activity, JNKs are thought to be the principal factors involved in c- jun up-regulation. Hypertrophy in primary cultures of cardiac myocytes is induced by endothelin-1, phenylephrine or PMA, probably through activation of one or more of the MAPK family. These three agonists increased c- jun mRNA with the rank order of potency of PMA approximately endothelin-1>phenylephrine. Up-regulation of c- jun mRNA by endothelin-1 was attenuated by inhibitors of protein kinase C (GF109203X) and the extracellular signal-regulated kinase (ERK) cascade (PD98059 or U0126), but not by inhibitors of the JNK (SP600125) or p38-MAPK (SB203580) cascades. Hyperosmotic shock (0.5 M sorbitol) powerfully activates JNKs, but did not increase c- jun mRNA. These data suggest that ERKs, rather than JNKs, are required for c- jun up-regulation. However, endothelin-1 and phenylephrine induced greater up-regulation of c-Jun protein than PMA and phosphorylation of c-Jun(Ser-63/73) correlated with the level of c-Jun protein. Up-regulation of c-Jun protein by endothelin-1 was attenuated by inhibitors of protein kinase C and the ERK cascade, probably correlating with a primary input of ERKs into transcription. In addition, SP600125 inhibited the phosphorylation of c-Jun(Ser-63/73), attenuated the increase in c-Jun protein induced by endothelin-1 and increased the rate of c-Jun degradation. Thus whereas ERKs are the principal MAPKs required for c- jun transcription, JNKs are necessary to stabilize c-Jun for efficient up-regulation of the protein.
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Affiliation(s)
- Angela Clerk
- Cardiac Medicine Section, National Heart and Lung Institute Division, Faculty of Medicine, Imperial College School of Science, Technology and Medicine, Dovehouse Street, London SW3 6LY, UK.
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89
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Shin SY, Ko J, Chang JS, Min DS, Choi C, Bae SS, Kim MJ, Hyun DS, Kim JH, Han MY, Kim YH, Kim YS, Na DS, Suh PG, Lee YH. Negative regulatory role of overexpression of PLC gamma 1 in the expression of early growth response 1 gene in rat 3Y1 fibroblasts. FASEB J 2002; 16:1504-14. [PMID: 12374773 DOI: 10.1096/fj.02-0022com] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The early growth response 1 (Egr-1) gene product is a transcription factor that functions as an oikis factor. Loss of Egr-1 expression is closely associated with tumor formation. Phospholipase Cgamma1 (PLCgamma1) is overexpressed in some tumors, and its overexpression causes anchorage-independent growth. Here we report that overexpression of PLCgamma1 and SH2-SH3 domain of PLCgamma1 decreased induction of Egr-1 and the Egr-1-regulated genes TSP-1 and PAI-1. Results from the nuclear run-on assay and transfection experiment with the proximal 455 base pair region of the Egr-1 promoter (-454 to +1) showed that Egr-1 transcriptional activity was suppressed in PLCgamma1-3Y1 cells whereas decay of Egr-1 mRNA was similar in both cell lines. Serum response element- and ternary complex factor Elk-1-mediated transcriptional activation of the reporter gene in response to EGF were also inhibited in PLCgamma1-3Y1 cells. Pretreatment with the protein synthesis inhibitor cycloheximide (CHX) partially abrogated the serum-induced suppression of Egr-1 transcription in PLCgamma1-3Y1 cells, suggesting that a CHX-sensitive factor(s) is involved in the suppression of Egr-1 transcription in PLCgamma1-3Y1 cells. Our results demonstrated that overexpression of PLCgamma1 functions as a negative modulator of the tumor suppressor Egr-1 gene expression, possibly through inhibition of Elk-1-dependent transcriptional activity.
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Affiliation(s)
- Soon Young Shin
- Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, Daegu, Korea 705-717
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90
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Srivastava AK. Hyperglycemia-induced protein kinase signaling pathways in vascular smooth muscle cells: implications in the pathogenesis of vascular dysfunction in diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 498:311-8. [PMID: 11900384 DOI: 10.1007/978-1-4615-1321-6_39] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- A K Srivastava
- Research Centre, Centre hospitalier de l'Université de Montréal-Hôtel-Dieu, Department of Medicine, University of Montréal, Québec, Canada.
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91
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Patel J, McLeod LE, Vries RGJ, Flynn A, Wang X, Proud CG. Cellular stresses profoundly inhibit protein synthesis and modulate the states of phosphorylation of multiple translation factors. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:3076-85. [PMID: 12071973 DOI: 10.1046/j.1432-1033.2002.02992.x] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have examined the effects of widely used stress-inducing agents on protein synthesis and on regulatory components of the translational machinery. The three stresses chosen, arsenite, hydrogen peroxide and sorbitol, exert their effects in quite different ways. Nonetheless, all three rapidly ( approximately 30 min) caused a profound inhibition of protein synthesis. In each case this was accompanied by dephosphorylation of the eukaryotic initiation factor (eIF) 4E-binding protein 1 (4E-BP1) and increased binding of this repressor protein to eIF4E. Binding of 4E-BP1 to eIF4E correlated with loss of eIF4F complexes. Sorbitol and hydrogen peroxide each caused inhibition of the 70-kDa ribosomal protein S6 kinase, while arsenite activated it. The effects of stresses on the phosphorylation of eukaryotic elongation factor 2 also differed: oxidative stress elicited a marked increase in eEF2 phosphorylation, which is expected to contribute to inhibition of translation, while the other stresses did not have this effect. Although all three proteins (4E-BP1, p70 S6 kinase and eEF2) can be regulated through the mammalian target of rapamycin (mTOR), our data imply that stresses do not interfere with mTOR function but act in different ways on these three proteins. All three stresses activate the p38 MAP kinase pathway but we were able to exclude a role for this in their effects on 4E-BP1. Our data reveal that these stress-inducing agents, which are widely used to study stress-signalling in mammalian cells, exert multiple and complex inhibitory effects on the translational machinery.
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Affiliation(s)
- Jashmin Patel
- Department of Biosciences, University of Kent at Canterbury, Canterbury, UK
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92
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Hu CD, Chinenov Y, Kerppola TK. Visualization of interactions among bZIP and Rel family proteins in living cells using bimolecular fluorescence complementation. Mol Cell 2002; 9:789-98. [PMID: 11983170 DOI: 10.1016/s1097-2765(02)00496-3] [Citation(s) in RCA: 1182] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Networks of protein interactions coordinate cellular functions. We describe a bimolecular fluorescence complementation (BiFC) assay for determination of the locations of protein interactions in living cells. This approach is based on complementation between two nonfluorescent fragments of the yellow fluorescent protein (YFP) when they are brought together by interactions between proteins fused to each fragment. BiFC analysis was used to investigate interactions among bZIP and Rel family transcription factors. Regions outside the bZIP domains determined the locations of bZIP protein interactions. The subcellular sites of protein interactions were regulated by signaling. Cross-family interactions between bZIP and Rel proteins affected their subcellular localization and modulated transcription activation. These results attest to the general applicability of the BiFC assay for studies of protein interactions.
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Affiliation(s)
- Chang-Deng Hu
- Howard Hughes Medical Institute and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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93
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Chan ASL, Lai FPL, Lo RKH, Voyno-Yasenetskaya TA, Stanbridge EJ, Wong YH. Melatonin mt1 and MT2 receptors stimulate c-Jun N-terminal kinase via pertussis toxin-sensitive and -insensitive G proteins. Cell Signal 2002; 14:249-57. [PMID: 11812653 DOI: 10.1016/s0898-6568(01)00240-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Melatonin is a pineal hormone involved in neuroendocrine processes in mammals. It has been shown that melatonin inhibits the enzymatic activities of adenylyl cyclases and the transcriptional activities of CREB. In this report, we demonstrate that 2-iodomelatonin (2IMT) treatment on COS-7 cells transfected with melatonin receptors (mt1 and MT2) induces c-Jun N-terminal kinase (JNK) activation, which is pertussis toxin (PTX)-sensitive, Ras/Rac-dependent and may involve Src-family protein tyrosine kinases. Moreover, PTX-insensitive Gs, Gz and G16 are capable of linking activated melatonin receptors to the stimulation of JNK. Agonist stimulation on PTX-pretreated COS-7 cells overexpressing mt1 receptor, Galpha(s) and adenylyl cyclase VI led to increased cAMP accumulation. Stimulation of endogenous mt1 receptors in MCF-7 cells was associated with the activation of both JNK and extracellular signal-regulated kinase (ERK). This report demonstrates the stimulatory effect of melatonin receptors on JNK, and provides experimental evidence for a functional coupling between the G(i)-coupled melatonin receptor and Gs, in terms of adenylyl cyclase activation.
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MESH Headings
- Adenylate Cyclase Toxin
- Animals
- COS Cells
- Chlorocebus aethiops
- GTP-Binding Protein alpha Subunits
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- GTP-Binding Proteins/metabolism
- Heterotrimeric GTP-Binding Proteins/metabolism
- Humans
- JNK Mitogen-Activated Protein Kinases
- MAP Kinase Signaling System/physiology
- Melatonin/analogs & derivatives
- Melatonin/metabolism
- Melatonin/pharmacology
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinase 8
- Mitogen-Activated Protein Kinase 9
- Mitogen-Activated Protein Kinases/metabolism
- Molecular Weight
- Pertussis Toxin
- Proto-Oncogene Proteins p21(ras)/metabolism
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Melatonin
- Tumor Cells, Cultured
- Virulence Factors, Bordetella/pharmacology
- rac1 GTP-Binding Protein/metabolism
- src-Family Kinases/metabolism
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Affiliation(s)
- Anthony S L Chan
- Department of Biochemistry the Biotechnology Research Institute, and the Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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94
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Stocco CO, Lau LF, Gibori G. A calcium/calmodulin-dependent activation of ERK1/2 mediates JunD phosphorylation and induction of nur77 and 20alpha-hsd genes by prostaglandin F2alpha in ovarian cells. J Biol Chem 2002; 277:3293-302. [PMID: 11719525 DOI: 10.1074/jbc.m110936200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously demonstrated that prostaglandin F(2alpha) (PGF(2alpha)) induces a rapid and transient expression of Nur77 in luteal cells. We have shown that Nur77 plays an important role in ovarian physiology by mediating the PGF(2alpha) induction of 20alpha-HSD, a steroidogenic enzyme involved in the catabolism of progesterone. In this report we established, using luteinized granulosa cells, that PGF(2alpha) stimulates in vitro nur77 expression in a time- and dose-dependent manner. Serial 5'-deletion of the nur77 promoter revealed that the necessary and sufficient elements for PGF(2alpha) induction of Nur77 promoter activity are located between the nucleotides -86 and -33 upstream of the transcription start site, this region containing two AP1 elements. JunD binds to these AP1 sites, but its binding is not stimulated by PGF(2alpha). However, mutation of the AP1 sites as well as a dominant-negative JunD abolished nur77 induction by PGF(2alpha). PGF(2alpha) induces phosphorylation of JunD bound to the nur77 promoter. Stimulation of nur77 expression and JunD phosphorylation were prevented by inhibitors of calcium, calmodulin, or ERK1/2 kinase. PGF(2alpha)-induced ERK1/2 phosphorylation was prevented by calcium/calmodulin inhibitors. We conclude that activation of JunD through a calmodulim-dependent activation of ERK1/2 mediates nur77 induction by PGF(2alpha). Finally, we demonstrated that this molecular mechanism also mediates 20alpha-hsd induction.
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Affiliation(s)
- Carlos O Stocco
- Department of Physiology and Biophysics, University of Illinois College of Medicine, Chicago, Illinois 60612, USA
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95
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Jarosinski KW, Whitney LW, Massa PT. Specific deficiency in nuclear factor-kappaB activation in neurons of the central nervous system. J Transl Med 2001; 81:1275-88. [PMID: 11555675 DOI: 10.1038/labinvest.3780341] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The expression and activation of nuclear factor-kappaB (NF-kappaB) in neurons and glia of the central nervous system (CNS) has been intensely investigated because of its potential importance in understanding how this multifunctional transcription factor controls developmental and pathological processes. In particular, there has been interest in how NF-kappaB may be differentially regulated in these two major functional subgroups of cells in the CNS to provide for specific responses to various stimuli. Of special interest are responses to both proinflammatory cytokines and microbial products that signal from specific cell receptors to activate NF-kappaB. In the present studies, both neurons and glia (astrocytes) in vivo expressed latent cytoplasmic NF-kappaB analyzed by immunofluorescence microscopy and electrophoretic mobility shift analysis. In vitro, neurons and astrocytes expressed comparable levels of latent NF-kappaB molecules, but NF-kappaB nuclear localization stimulated by proinflammatory cytokines or microbial products was markedly deficient in neurons. In accord with this finding, the rapid degradation of inhibitor of NF-kappaB alpha (IkappaBalpha) that is seen in astrocytes did not occur in neurons in response to these agents. However, long-term exposure to translational inhibitors resulted in IkappaBalpha decay and activation of latent NF-kappaB in neurons, indicating potential NF-kappaB activity in these cells. Analysis of NF-kappaB-responsive interferon regulatory factor-1 gene expression indicated that increased nuclear NF-kappaB in neurons had transcriptional potential. We conclude that mechanisms responsible for inducible targeting of IkappaBalpha are uniquely regulated in neurons and account for the hypo-responsiveness of these cells to signals generated during microbial infections in the CNS. Thus, modulation of signals that target IkappaBalpha degradation may be unique and a key component of specific NF-kappaB regulation in neurons.
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Affiliation(s)
- K W Jarosinski
- Department of Neurology, State University of New York Health Science Center, Syracuse, New York 13210, USA
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96
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Akiyama M, Minami Y, Nakajima T, Moriya T, Shibata S. Calcium and pituitary adenylate cyclase-activating polypeptide induced expression of circadian clock gene mPer1 in the mouse cerebellar granule cell culture. J Neurochem 2001; 78:499-508. [PMID: 11483652 DOI: 10.1046/j.1471-4159.2001.00452.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mammalian circadian clock genes Per1 and Per2 are rhythmically expressed not only in the suprachiasmatic nucleus where the mammalian circadian clock exists, but also in other brain regions and peripheral tissues. The induced circadian oscillation of Per genes after treatment with high concentrations of serum or various drugs in cultured cells suggests the ubiquitous existence of the oscillatory mechanism. These treatments also result in a rapid surge of expression of Per1. It has been shown that multiple signaling pathways are involved in Per1 gene induction in culture cells. We used a dispersed primary cell culture made up of mouse cerebellar granule cells to examine the stimuli inducing the mPer genes and their signaling pathways in neuronal tissues expressing mPer genes. We demonstrated that mPer1, but not mPer2, mRNA expression was dependent on the depolarization state controlled by extracellular KCl concentration in the granule cell culture. Nifedipine treatment reduced mPer1 induction, suggesting that mPer1 mRNA expression depends on intracellular calcium concentration regulated through a voltage-dependent Ca2+ channel. Transient mPer1 mRNA induction was observed after elevating KCl concentration in the medium from 5 mM to 25 mM. This increased expression was suppressed by a calmodulin antagonist, or CaMKII/IV inhibitor, but not by MEK inhibitors. Addition of pituitary adenylate cyclase-activating polypeptide-38 to the medium also induced transient Per1 gene expression. This induction was mimicked by dibutyryl-cAMP and suppressed by a protein kinase A (PKA) inhibitor, but not by MEK inhibitors. These results suggest that Ca2+/calmodulin-dependent protein kinase II/IV- and PKA-dependent pathways are involved in high-KCl and PACAP-induced mPer1 induction, respectively, and neural tissues use multiple signaling pathways for mPer1 induction similar to culture cells.
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Affiliation(s)
- M Akiyama
- Department of Pharmacology and Brain Science, School of Human Sciences, Waseda University, Tokorozawa, Saitama, Japan
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97
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Botella JA, Baines IA, Williams DD, Goberdhan DC, Proud CG, Wilson C. The Drosophila cell shape regulator c-Jun N-terminal kinase also functions as a stress-activated protein kinase. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2001; 31:839-847. [PMID: 11439243 DOI: 10.1016/s0965-1748(01)00029-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mammalian c-Jun N-terminal kinases (JNKs) are members of a group of stress-activated intracellular signalling molecules within the MAP kinase family. Molecular genetic analysis of a highly evolutionarily conserved Drosophila JNK homologue, DJNK, has demonstrated that this molecule plays an essential developmental role in cell shape regulation. However, it remains to be determined whether DJNK also responds to the broad range of cellular stresses and other stimuli that affect its mammalian counterpart. Here we demonstrate that c-Jun, a substrate for mammalian JNKs, is a specific substrate for DJNK and that an antiserum that cross-reacts with activated mammalian JNK at the conserved threonyl-prolyl-tyrosyl (TPY) motif within the activation loop also specifically recognises the activated form of DJNK. Using these two assays, we show that DJNK activity is stimulated in cultured cells by several treatments that activate mammalian JNKs, including addition of arsenite, vanadate and ceramide derivatives. It is therefore concluded that in addition to its essential developmental functions, DJNK plays an important role in stress responses that mirrors its mammalian counterpart.
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Affiliation(s)
- J A Botella
- Research School of Biosciences, Department of Biosciences, University of Kent, Canterbury, CT2 7NJ, Kent, UK
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98
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Nomura M, Kaji A, Ma WY, Zhong S, Liu G, Bowden GT, Miyamoto KI, Dong Z. Mitogen- and stress-activated protein kinase 1 mediates activation of Akt by ultraviolet B irradiation. J Biol Chem 2001; 276:25558-67. [PMID: 11350959 DOI: 10.1074/jbc.m101164200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we investigated the mechanism by which UVB irradiation activates Akt (also known as protein kinase B (PKB)) in mouse epidermal JB6 cells. Treatment with a phosphatidylinositol 3-kinase inhibitor, LY 294002, or expression of a dominant negative mutant of p85 (regulatory component of phosphatidylinositol 3-kinase) inhibited UVB-induced Akt activation. Interestingly, Akt activation by UVB was attenuated by treatment with PD 98059, a specific mitogen-activated protein kinase/extracellular signal-regulated protein kinase (Erk) kinase 1 inhibitor, or SB 202190, a specific p38 kinase inhibitor. Furthermore, the expression of a dominant negative mutant of Erk2 or p38 kinase, but not that of c-Jun N-terminal kinase 1 (JNK1), blocked UVB-induced Akt activation. The expression of a dominant negative mutant of p85 or treatment with LY 294002 also inhibited UVB-induced Erk phosphorylation. The UVB-activated mitogen-activated protein kinase members, which were immunoprecipitated from cells exposed to UVB, did not phosphorylate Akt. Instead, Akt was phosphorylated at both threonine 308 and serine 473 and activated by UVB-activated mitogen- and stress-activated protein kinase 1 (Msk1). The expression of a Msk1 C-terminal kinase-dead mutant inhibited UVB-induced phosphorylation and activation of Akt. These data thus suggested that UVB-induced Akt activation was mediated through Msk1, which is a downstream kinase of the Erk and p38 kinase signaling pathways.
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Affiliation(s)
- M Nomura
- Hormel Institute, University of Minnesota, 801 16th Ave. NE, Austin, MN 55912, USA
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99
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Vanhoutte P, Nissen JL, Brugg B, Gaspera BD, Besson MJ, Hipskind RA, Caboche J. Opposing roles of Elk-1 and its brain-specific isoform, short Elk-1, in nerve growth factor-induced PC12 differentiation. J Biol Chem 2001; 276:5189-96. [PMID: 11050086 DOI: 10.1074/jbc.m006678200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ternary complex factor Elk-1, a major nuclear target of extracellular signal-regulated kinases, is a strong transactivator of serum-responsive element (SRE) driven gene expression. We report here that mature brain neurons and nerve growth factor (NGF)-differentiated PC12 cells also express a second, smaller isoform of Elk-1, short Elk-1 (sElk-1). sElk-1 arises from an internal translation start site in the Elk-1 sequence, which generates a protein lacking the first 54 amino acids of the DNA-binding domain. This deletion severely compromises the ability of sElk-1 to form complexes with serum response factor on the SRE in vitro and to activate SRE reporter genes in the presence of activated Ras. Instead, sElk, but not a mutant that cannot be phosphorylated, inhibits transactivation driven by Elk-1. More pertinent to the neuronal-specific expression of sElk-1, we show it plays an opposite role to Elk-1 in potentiating NGF-driven PC12 neuronal differentiation. Overexpression of sElk-1 but not Elk-1 increases neurite extension, an effect critically linked to its phosphorylation. Interestingly, in the presence of sElk-1, Elk-1 loses its strictly nuclear localization to resemble the nuclear/cytoplasm pattern observed in the mature brain. This is blocked by mutating a normally cryptic nuclear export signal in Elk-1. These data provide new insights into molecular events underlying neuronal differentiation of PC12 cells mediated by the NGF-ERK signaling cascade.
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Affiliation(s)
- P Vanhoutte
- Laboratoire de Neurochimie-Anatomie, Institut des Neurosciences, CNRS-UMR 7624, Université Pierre et Marie Curie, 75005 Paris, France
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100
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Abstract
A central feature of drugs of abuse is to induce gene expression in discrete brain structures that are critically involved in behavioral responses related to addictive processes. Although extracellular signal-regulated kinase (ERK) has been implicated in several neurobiological processes, including neuronal plasticity, its role in drug addiction remains poorly understood. This study was designed to analyze the activation of ERK by cocaine, its involvement in cocaine-induced early and long-term behavioral effects, as well as in gene expression. We show, by immunocytochemistry, that acute cocaine administration activates ERK throughout the striatum, rapidly but transiently. This activation was blocked when SCH 23390 [a specific dopamine (DA)-D1 antagonist] but not raclopride (a DA-D2 antagonist) was injected before cocaine. Glutamate receptors of NMDA subtypes also participated in ERK activation, as shown after injection of the NMDA receptor antagonist MK 801. The systemic injection of SL327, a selective inhibitor of the ERK kinase MEK, before cocaine, abolished the cocaine-induced ERK activation and decreased cocaine-induced hyperlocomotion, indicating a role of this pathway in events underlying early behavioral responses. Moreover, the rewarding effects of cocaine were abolished by SL327 in the place-conditioning paradigm. Because SL327 antagonized cocaine-induced c-fos expression and Elk-1 hyperphosphorylation, we suggest that the ERK intracellular signaling cascade is also involved in the prime burst of gene expression underlying long-term behavioral changes induced by cocaine. Altogether, these results reveal a new mechanism to explain behavioral responses of cocaine related to its addictive properties.
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