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Cayla M, Rachidi N, Leclercq O, Schmidt-Arras D, Rosenqvist H, Wiese M, Späth GF. Transgenic analysis of the Leishmania MAP kinase MPK10 reveals an auto-inhibitory mechanism crucial for stage-regulated activity and parasite viability. PLoS Pathog 2014; 10:e1004347. [PMID: 25232945 PMCID: PMC4169501 DOI: 10.1371/journal.ppat.1004347] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 07/17/2014] [Indexed: 01/15/2023] Open
Abstract
Protozoan pathogens of the genus Leishmania have evolved unique signaling mechanisms that can sense changes in the host environment and trigger adaptive stage differentiation essential for host cell infection. The signaling mechanisms underlying parasite development remain largely elusive even though Leishmania mitogen-activated protein kinases (MAPKs) have been linked previously to environmentally induced differentiation and virulence. Here, we unravel highly unusual regulatory mechanisms for Leishmania MAP kinase 10 (MPK10). Using a transgenic approach, we demonstrate that MPK10 is stage-specifically regulated, as its kinase activity increases during the promastigote to amastigote conversion. However, unlike canonical MAPKs that are activated by dual phosphorylation of the regulatory TxY motif in the activation loop, MPK10 activation is independent from the phosphorylation of the tyrosine residue, which is largely constitutive. Removal of the last 46 amino acids resulted in significantly enhanced MPK10 activity both for the recombinant and transgenic protein, revealing that MPK10 is regulated by an auto-inhibitory mechanism. Over-expression of this hyperactive mutant in transgenic parasites led to a dominant negative effect causing massive cell death during amastigote differentiation, demonstrating the essential nature of MPK10 auto-inhibition for parasite viability. Moreover, phosphoproteomics analyses identified a novel regulatory phospho-serine residue in the C-terminal auto-inhibitory domain at position 395 that could be implicated in kinase regulation. Finally, we uncovered a feedback loop that limits MPK10 activity through dephosphorylation of the tyrosine residue of the TxY motif. Together our data reveal novel aspects of protein kinase regulation in Leishmania, and propose MPK10 as a potential signal sensor of the mammalian host environment, whose intrinsic pre-activated conformation is regulated by auto-inhibition. Leishmaniasis is an important human disease caused by Leishmania parasites. A crucial aspect of Leishmania infectivity is its capacity to sense different environments and adapt for survival inside insect vector and vertebrate host by stage differentiation. This process is triggered by environmental changes encountered in these organisms, including temperature and pH shifts, which usually are sensed and transduced by signaling cascades including protein kinases and their substrates. In this study, we analyzed the regulation of the Leishmania mitogen-activated protein kinase MPK10 using protein purified from transgenic parasites and combining site-directed mutagenesis and activity tests. We demonstrate that this kinase is activated during parasite differentiation and regulated by an atypical mechanism involving auto-inhibition, which is essential for parasite viability.
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Affiliation(s)
- Mathieu Cayla
- Institut Pasteur and Centre National de la Recherche Scientifique URA 2581, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Najma Rachidi
- Institut Pasteur and Centre National de la Recherche Scientifique URA 2581, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Olivier Leclercq
- Institut Pasteur and Centre National de la Recherche Scientifique URA 2581, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Dirk Schmidt-Arras
- Institut Pasteur and Centre National de la Recherche Scientifique URA 2581, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Heidi Rosenqvist
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland
- Protein Research Group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Martin Wiese
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland
| | - Gerald F. Späth
- Institut Pasteur and Centre National de la Recherche Scientifique URA 2581, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
- * E-mail:
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ERK5/BMK1 is a novel target of the tumor suppressor VHL: implication in clear cell renal carcinoma. Neoplasia 2014; 15:649-59. [PMID: 23730213 DOI: 10.1593/neo.121896] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/20/2013] [Accepted: 03/24/2013] [Indexed: 11/18/2022] Open
Abstract
Extracellular signal-regulated kinase 5 (ERK5), also known as big mitogen-activated protein kinase (MAPK) 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL) gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well as the study of endogenous ERK5 in different experimental systems such as MCF7, HMEC, or Caki-2 cell lines. In fact, the specific knockdown of ERK5 in pVHL-negative cell lines promotes a decrease in proliferation and migration, supporting the role of this MAPK in cellular transformation. Furthermore, in a short series of fresh samples from human clear cell renal cell carcinoma, high levels of ERK5 correlate with more aggressive and metastatic stages of the disease. Therefore, our results provide new biochemical data suggesting that ERK5 is a novel target of the tumor suppressor VHL, opening a new field of research on the role of ERK5 in renal carcinomas.
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Antoon JW, Martin EC, Lai R, Salvo VA, Tang Y, Nitzchke AM, Elliott S, Nam SY, Xiong W, Rhodes LV, Collins-Burow B, David O, Wang G, Shan B, Beckman BS, Nephew KP, Burow ME. MEK5/ERK5 signaling suppresses estrogen receptor expression and promotes hormone-independent tumorigenesis. PLoS One 2013; 8:e69291. [PMID: 23950888 PMCID: PMC3739787 DOI: 10.1371/journal.pone.0069291] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 06/12/2013] [Indexed: 01/20/2023] Open
Abstract
Endocrine resistance and metastatic progression are primary causes of treatment failure in breast cancer. While mitogen activated protein kinases (MAPKs) are known to promote ligand-independent cell growth, the role of the MEK5-ERK5 pathway in the progression of clinical breast carcinoma remains poorly understood. Here, we demonstrated increased ERK5 activation in 30 of 39 (76.9%) clinical tumor samples, as well as across breast cancer cell systems. Overexpression of MEK5 in MCF-7 cells promoted both hormone-dependent and hormone-independent tumorigenesis in vitro and in vivo and conferred endocrine therapy resistance to previously sensitive breast cancer cells. Expression of MEK5 suppressed estrogen receptor (ER)α, but not ER-β protein levels, and abrogated downstream estrogen response element (ERE) transcriptional activity and ER-mediated gene transcription. Global gene expression changes associated with upregulation of MEK5 included increased activation of ER-α independent growth signaling pathways and promotion of epithelial-to-mesenchymal transition (EMT) markers. Taken together, our findings show that the MEK5-ERK5 pathway mediates progression to an ER(-), mesenchymal and endocrine therapy resistant phenotype. Given the need for new clinical therapeutic targets, our results demonstrate the therapeutic potential of targeting the MEK5-ERK5 pathway in breast cancer.
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Affiliation(s)
- James W. Antoon
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Elizabeth C. Martin
- Department of Medicine, Section of Hematology & Medical Oncology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Rongye Lai
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Bloomington, Indiana, United States of America
| | - Virgilo A. Salvo
- Department of Medicine, Section of Hematology & Medical Oncology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Yan Tang
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Ashley M. Nitzchke
- Department of Medicine, Section of Hematology & Medical Oncology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Steven Elliott
- Department of Medicine, Section of Hematology & Medical Oncology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Seung Yoon Nam
- Department of Chemistry, Xavier University, New Orleans, Louisiana, United States of America
| | - Wei Xiong
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Lyndsay V. Rhodes
- Department of Medicine, Section of Hematology & Medical Oncology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Bridgette Collins-Burow
- Department of Medicine, Section of Hematology & Medical Oncology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Odile David
- Department of Pathology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Guandi Wang
- Department of Chemistry, Xavier University, New Orleans, Louisiana, United States of America
| | - Bin Shan
- Department of Pulmonary Diseases, Critical Care, and Environmental Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Barbara S. Beckman
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
| | - Kenneth P. Nephew
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Bloomington, Indiana, United States of America
| | - Matthew E. Burow
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
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Elkins JM, Wang J, Deng X, Pattison MJ, Arthur JSC, Erazo T, Gomez N, Lizcano JM, Gray NS, Knapp S. X-ray crystal structure of ERK5 (MAPK7) in complex with a specific inhibitor. J Med Chem 2013; 56:4413-21. [PMID: 23656407 PMCID: PMC3683888 DOI: 10.1021/jm4000837] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The
protein kinase ERK5 (MAPK7) is an emerging drug target for
a variety of indications, in particular for cancer where it plays
a key role mediating cell proliferation, survival, epithelial–mesenchymal
transition, and angiogenesis. To date, no three-dimensional structure
has been published that would allow rational design of inhibitors.
To address this, we determined the X-ray crystal structure of the
human ERK5 kinase domain in complex with a highly specific benzo[e]pyrimido[5,4-b]diazepine-6(11H)-one inhibitor. The structure reveals that specific residue
differences in the ATP-binding site, compared to the related ERKs
p38s and JNKs, allow for the development of ERK5-specific inhibitors.
The selectivity of previously observed ERK5 inhibitors can also be
rationalized using this structure, which provides a template for future
development of inhibitors with potential for treatment of disease.
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Affiliation(s)
- Jonathan M Elkins
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, UK
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Glatz G, Gógl G, Alexa A, Reményi A. Structural mechanism for the specific assembly and activation of the extracellular signal regulated kinase 5 (ERK5) module. J Biol Chem 2013; 288:8596-8609. [PMID: 23382384 PMCID: PMC3605678 DOI: 10.1074/jbc.m113.452235] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mitogen-activated protein kinase (MAPK) activation depends on a linear binding motif found in all MAPK kinases (MKK). In addition, the PB1 (Phox and Bem1) domain of MKK5 is required for extracellular signal regulated kinase 5 (ERK5) activation. We present the crystal structure of ERK5 in complex with an MKK5 construct comprised of the PB1 domain and the linear binding motif. We show that ERK5 has distinct protein-protein interaction surfaces compared with ERK2, which is the closest ERK5 paralog. The two MAPKs have characteristically different physiological functions and their distinct protein-protein interaction surface topography enables them to bind different sets of activators and substrates. Structural and biochemical characterization revealed that the MKK5 PB1 domain cooperates with the MAPK binding linear motif to achieve substrate specific binding, and it also enables co-recruitment of the upstream activating enzyme and the downstream substrate into one signaling competent complex. Studies on present day MAPKs and MKKs hint on the way protein kinase networks may evolve. In particular, they suggest how paralogous enzymes with similar catalytic properties could acquire novel signaling roles by merely changing the way they make physical links to other proteins.
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Affiliation(s)
- Gábor Glatz
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Gergő Gógl
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Anita Alexa
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Attila Reményi
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary.
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56
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Kim M, Kim S, Lim JH, Lee C, Choi HC, Woo CH. Laminar flow activation of ERK5 protein in vascular endothelium leads to atheroprotective effect via NF-E2-related factor 2 (Nrf2) activation. J Biol Chem 2012; 287:40722-31. [PMID: 23043106 DOI: 10.1074/jbc.m112.381509] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Laminar flow protects from atherosclerosis in endothelium. RESULTS Laminar flow induces Nrf2 activation dependent on ERK5 activation, leading to up-regulation of downstream genes of Nrf2. CONCLUSION ERK5 requires Nrf2 activation to exert cytoprotective effect on HUVEC. ERK5 inhibitor BIX02189 regulates Nrf2 activation in vivo. SIGNIFICANCE Identifying ERK5 as a molecular target for regulating flow-mediating Nrf2-dependent gene expression may have significant therapeutic potential for treating atherosclerosis. Atherosclerosis is often observed in areas where disturbed flow is formed, whereas atheroprotective region is found in areas where steady laminar flow is developed. It has been reported that some genes activated by blood flow play important roles in vascular function and pathogenesis of atherosclerosis. Extracellular signal-regulated kinase 5 (ERK5) has been reported to regulate endothelial integrity and protect from vascular dysfunction and disease under laminar flow. Krüppel-like factor 2 (KLF2) and NF-E2-related factor 2 (Nrf2) are major transcriptional factors that contribute to anti-atherogenic responses under laminar flow. Implication of ERK5 in laminar flow-mediated regulation of KLF2-dependent gene has been established, whereas the role of ERK5 in laminar flow-mediated activation of Nrf2 pathway has not been addressed yet. In this study, we found that the blockage of ERK5 either by genetic depletion with siRNA or by biochemical inactivation with a specific chemical compound inhibited laminar flow-induced up-regulation of Nrf2-dependent gene expressions, whereas activation of ERK5 increased transcriptional activity and nuclear translocation of Nrf2, which suggests that ERK5 mediates laminar flow-induced up-regulation of Nrf2-dependent gene expression. Further functional studies showed that ERK5 provides protection against oxidative stress-induced cytotoxicity dependent on Nrf2. Molecular interaction between ERK5 and Nrf2 was further induced by laminar flow. Finally, flow-dependent nuclear localization of Nrf2 was inhibited by BIX02189, a specific inhibitor of MEK5, in aorta of mice in vivo. Collectively, these data demonstrate that laminar flow-induced activation of ERK5-Nrf2 signal pathway plays a critical role for anti-inflammatory and anti-apoptotic mechanism in endothelial cells.
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Affiliation(s)
- Miso Kim
- Department of Pharmacology, Yeungnam University College of Medicine, 317-1 Daemyung-dong, Daegu 705-717, Korea
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57
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Nithianandarajah-Jones GN, Wilm B, Goldring CEP, Müller J, Cross MJ. ERK5: structure, regulation and function. Cell Signal 2012; 24:2187-96. [PMID: 22800864 DOI: 10.1016/j.cellsig.2012.07.007] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 07/09/2012] [Indexed: 01/06/2023]
Abstract
Extracellular signal-regulated kinase 5 (ERK5), also termed big mitogen-activated protein kinase-1 (BMK1), is the most recently identified member of the mitogen-activated protein kinase (MAPK) family and consists of an amino-terminal kinase domain, with a relatively large carboxy-terminal of unique structure and function that makes it distinct from other MAPK members. It is ubiquitously expressed in numerous tissues and is activated by a variety of extracellular stimuli, such as cellular stresses and growth factors, to regulate processes such as cell proliferation and differentiation. Targeted deletion of Erk5 in mice has revealed that the ERK5 signalling cascade plays a critical role in cardiovascular development and vascular integrity. Recent data points to a potential role in pathological conditions such as cancer and tumour angiogenesis. This review focuses on the physiological and pathological role of ERK5, the regulation of this kinase and the recent development of small molecule inhibitors of the ERK5 signalling cascade.
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Affiliation(s)
- Gopika N Nithianandarajah-Jones
- MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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Yin Y, She H, Li W, Yang Q, Guo S, Mao Z. Modulation of Neuronal Survival Factor MEF2 by Kinases in Parkinson's Disease. Front Physiol 2012; 3:171. [PMID: 22661957 PMCID: PMC3362091 DOI: 10.3389/fphys.2012.00171] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 05/10/2012] [Indexed: 12/15/2022] Open
Abstract
Parkinson’s disease (PD) is the second most common neurodegenerative disorder due to selective death of neurons in the substantia nigra pars compacta. The cause of cell death remains largely unknown. Myocyte enhancer factor 2 (MEF2) is a group of transcriptional factors required to regulate neuronal development, synaptic plasticity, as well as survival. Recent studies show that MEF2 functions are regulated in multiple subcellular organelles and suggest that dysregulation of MEF2 plays essential roles in the pathogenesis of PD. Many kinases associated with transcription, translation, protein misfolding, autophagy, and cellular energy homeostasis are involved in the neurodegenerative process. Following the first demonstration that mitogen-activated protein kinase p38 (p38 MAPK) directly phosphorylates and activates MEF2 to promote neuronal survival, several other kinase regulators of MEF2s have been identified. These include protein kinase A and extracellular signal regulated kinase 5 as positive MEF2 regulators, and cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3β as negative regulators in response to diverse toxic signals relevant to PD. It is clear that MEF2 has emerged as a key point where survival and death signals converge to exert their regulatory effects, and dysregulation of MEF2 function in multiple subcellular organelles may underlie PD pathogenesis. Moreover, several other kinases such as leucine-rich repeat kinase 2 and PTEN-induced putative kinase 1 (PINK1) are of particular interest due to their potential interaction with MEF2.
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Affiliation(s)
- Yue Yin
- Institute of Plastic Surgery, Xijing Hospital, Fourth Military Medical University Xi'an, Shaanxi, China
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Abstract
The MEK5 [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase 5]/ERK5 pathway is the least well studied MAPK signalling module. It has been proposed to play a role in the pathology of cancer. In the present paper, we review the role of the MEK5/ERK5 pathway using the 'hallmarks of cancer' as a framework and consider how this pathway is deregulated. As well as playing a key role in endothelial cell survival and tubular morphogenesis during tumour neovascularization, ERK5 is also emerging as a regulator of tumour cell invasion and migration. Several oncogenes can stimulate ERK5 activity, and protein levels are increased by a novel amplification at chromosome locus 17p11 and by down-regulation of the microRNAs miR-143 and miR-145. Together, these finding underscore the case for further investigation into understanding the role of ERK5 in cancer.
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Shannon LA, McBurney TM, Wells MA, Roth ME, Calloway PA, Bill CA, Islam S, Vines CM. CCR7/CCL19 controls expression of EDG-1 in T cells. J Biol Chem 2012; 287:11656-64. [PMID: 22334704 DOI: 10.1074/jbc.m111.310045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
T lymphocytes circulate between the blood, tissues, and lymph. These T cells carry out immune functions, using the C-C chemokine receptor 7 (CCR7) and its cognate ligands, CCL19 and CCL21, to enter and travel through the lymph nodes. Distinct roles for each ligand in regulating T lymphocyte trafficking have remained elusive. We report that in the human T cell line HuT78 and in primary murine T lymphocytes, signaling from CCR7/CCL19 leads to increased expression and phosphorylation of extracellular signal-regulated kinase 5 (ERK5) within eight hours of stimulation. Within 48-72 h we observed peak levels of endothelial differentiation gene 1 (EDG-1), which mediates the egress of T lymphocytes from lymph nodes. The increased expression of EDG-1 was preceded by up-regulation of its transcription factor, Krüppel-like factor 2 (KLF-2). To determine the cellular effect of disrupting ERK5 signaling from CCR7, we examined the migration of ERK5(flox/flox)/Lck-Cre murine T cells to EDG-1 ligands. While CCL19-stimulated ERK5(flox/flox) naïve T cells showed increased migration to EDG-1 ligands at 48 h, the migration of ERK5(flox/flox)/Lck-Cre T cells remained at a basal level. Accordingly, we define a novel signaling pathway that controls EDG-1 up-regulation following stimulation of T cells by CCR7/CCL19. This is the first report to link the two signaling events that control migration through the lymph nodes: CCR7 mediates entry into the lymph nodes and EDG-1 signaling controls their subsequent exit.
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Affiliation(s)
- Laura A Shannon
- Department of Microbiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Gilley R, Lochhead PA, Balmanno K, Oxley D, Clark J, Cook SJ. CDK1, not ERK1/2 or ERK5, is required for mitotic phosphorylation of BIMEL. Cell Signal 2012; 24:170-80. [DOI: 10.1016/j.cellsig.2011.08.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 08/29/2011] [Indexed: 01/05/2023]
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Lim JH, Woo CH. Laminar flow activation of ERK5 leads to cytoprotective effect via CHIP-mediated p53 ubiquitination in endothelial cells. Anat Cell Biol 2011; 44:265-73. [PMID: 22254155 PMCID: PMC3254880 DOI: 10.5115/acb.2011.44.4.265] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 11/21/2011] [Accepted: 11/23/2011] [Indexed: 12/04/2022] Open
Abstract
Atherosclerosis is readily observed in areas where disturbed flow is formed, while the atheroprotective region is found in areas with steady laminar flow (L-flow). It has been established that L-flow protects endothelial cells against endothelial dysfunction, including apoptosis and inflammation. It has also been reported that extracellular signal-regulated kinase 5 (ERK5) regulated endothelial integrity and protected endothelial cells from vascular dysfunction and disease under L-flow. However, the molecular mechanism by which L-flow-induced ERK5 activation inhibits endothelial apoptosis has not yet been determined. Transcription factor p53 is a major pro-apoptotic factor which contributes to apoptosis in various cell types. In this study, we found that 15-deoxy-Δ(12,14)-prostaglandin J2 induced p53 expression and that endothelial apoptosis was reduced under the L-flow condition. This anti-apoptotic response was reversed by the biochemical inhibition of ERK5 activation. It was also found that activation of ERK5 protected endothelial apoptosis in a C terminus of Hsc70-interacting protein (CHIP) ubiquitin ligase-dependent manner. Moreover, molecular interaction between ERK5-CHIP and p53 ubiquitination were addressed with a CHIP ubiquitin ligase activity assay. Taken together, our data suggest that the ERK5-CHIP signal module elicited by L-flow plays an important role in the anti-apoptotic mechanism in endothelial cells.
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Affiliation(s)
- Jae Hyang Lim
- Department of Biology and Center for Inflammation, Immunity and Infection, Georgia State University, Atlanta, GA, USA
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Li M, Liu J, Zhang C. Evolutionary history of the vertebrate mitogen activated protein kinases family. PLoS One 2011; 6:e26999. [PMID: 22046431 PMCID: PMC3202601 DOI: 10.1371/journal.pone.0026999] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Accepted: 10/07/2011] [Indexed: 11/18/2022] Open
Abstract
Background The mitogen activated protein kinases (MAPK) family pathway is implicated in diverse cellular processes and pathways essential to most organisms. Its evolution is conserved throughout the eukaryotic kingdoms. However, the detailed evolutionary history of the vertebrate MAPK family is largely unclear. Methodology/Principal Findings The MAPK family members were collected from literatures or by searching the genomes of several vertebrates and invertebrates with the known MAPK sequences as queries. We found that vertebrates had significantly more MAPK family members than invertebrates, and the vertebrate MAPK family originated from 3 progenitors, suggesting that a burst of gene duplication events had occurred after the divergence of vertebrates from invertebrates. Conservation of evolutionary synteny was observed in the vertebrate MAPK subfamilies 4, 6, 7, and 11 to 14. Based on synteny and phylogenetic relationships, MAPK12 appeared to have arisen from a tandem duplication of MAPK11 and the MAPK13-MAPK14 gene unit was from a segmental duplication of the MAPK11-MAPK12 gene unit. Adaptive evolution analyses reveal that purifying selection drove the evolution of MAPK family, implying strong functional constraints of MAPK genes. Intriguingly, however, intron losses were specifically observed in the MAPK4 and MAPK7 genes, but not in their flanking genes, during the evolution from teleosts to amphibians and mammals. The specific occurrence of intron losses in the MAPK4 and MAPK7 subfamilies might be associated with adaptive evolution of the vertebrates by enhancing the gene expression level of both MAPK genes. Conclusions/Significance These results provide valuable insight into the evolutionary history of the vertebrate MAPK family.
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Affiliation(s)
- Meng Li
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Jun Liu
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Chiyu Zhang
- Institute of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, China
- * E-mail:
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Drew BA, Burow ME, Beckman BS. MEK5/ERK5 pathway: the first fifteen years. Biochim Biophys Acta Rev Cancer 2011; 1825:37-48. [PMID: 22020294 DOI: 10.1016/j.bbcan.2011.10.002] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 10/07/2011] [Indexed: 12/22/2022]
Abstract
While conventional MAP kinase pathways are one of the most highly studied signal transduction molecules, less is known about the MEK5 signaling pathway. This pathway has been shown to play a role in normal cell growth cycles, survival and differentiation. The MEK5 pathway is also believed to mediate the effects of a number of oncogenes. MEK5 is the upstream activator of ERK5 in many epithelial cells. Activation of the MEK-MAPK pathway is a frequent event in malignant tumor formation and contributes to chemoresistance and anti-apoptotic signaling. This pathway may be involved in a number of more aggressive, metastatic varieties of cancer due to its role in cell survival, proliferation and EMT transitioning. Further study of this pathway may lead to new prognostic factors and new drug targets to combat more aggressive forms of cancer.
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Affiliation(s)
- Barbara A Drew
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Razumovskaya E, Sun J, Rönnstrand L. Inhibition of MEK5 by BIX02188 induces apoptosis in cells expressing the oncogenic mutant FLT3-ITD. Biochem Biophys Res Commun 2011; 412:307-12. [DOI: 10.1016/j.bbrc.2011.07.089] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 07/21/2011] [Indexed: 01/24/2023]
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Katsarou K, Tsitoura P, Georgopoulou U. MEK5/ERK5/mef2: a novel signaling pathway affected by hepatitis C virus non-enveloped capsid-like particles. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1854-62. [PMID: 21767578 DOI: 10.1016/j.bbamcr.2011.06.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 06/24/2011] [Accepted: 06/27/2011] [Indexed: 11/17/2022]
Abstract
Hepatitis C virus (HCV) is an RNA positive strand virus, member of the Flaviviridae family. The viral particle is composed of a capsid containing the genome, surrounded by E1 and E2 proteins, however different forms of viral particles have been observed including non-enveloped particles. Previous reports have proposed that hepatitis C non-enveloped capsid-like particles (HCVne) enter cells of hepatic origin via clathrin-mediated endocytosis, during which different signaling events occur. In this report we show that HCVne particles are capable of inducing the recently discovered ERK5 pathway, in a dose dependent way. The ERK5 pathway can be activated by growth factors and other extracellular signals. This specific activation occurs through a well characterized upstream kinase, MEK5, and is capable of inducing gene regulation of mef2. In contrast, when HCV core structural and NS5A non-structural proteins were expressed endogenously no activation of this pathway was detected. These cell signaling events could be of critical importance and might give clues for the elucidation of cellular manifestations associated with HCV infection.
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67
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Nardozzi JD, Lott K, Cingolani G. Phosphorylation meets nuclear import: a review. Cell Commun Signal 2010; 8:32. [PMID: 21182795 PMCID: PMC3022542 DOI: 10.1186/1478-811x-8-32] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 12/23/2010] [Indexed: 12/18/2022] Open
Abstract
Phosphorylation is the most common and pleiotropic modification in biology, which plays a vital role in regulating and finely tuning a multitude of biological pathways. Transport across the nuclear envelope is also an essential cellular function and is intimately linked to many degeneration processes that lead to disease. It is therefore not surprising that phosphorylation of cargos trafficking between the cytoplasm and nucleus is emerging as an important step to regulate nuclear availability, which directly affects gene expression, cell growth and proliferation. However, the literature on phosphorylation of nucleocytoplasmic trafficking cargos is often confusing. Phosphorylation, and its mirror process dephosphorylation, has been shown to have opposite and often contradictory effects on the ability of cargos to be transported across the nuclear envelope. Without a clear connection between attachment of a phosphate moiety and biological response, it is difficult to fully understand and predict how phosphorylation regulates nucleocytoplasmic trafficking. In this review, we will recapitulate clue findings in the field and provide some general rules on how reversible phosphorylation can affect the nuclear-cytoplasmic localization of substrates. This is only now beginning to emerge as a key regulatory step in biology.
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Affiliation(s)
- Jonathan D Nardozzi
- Dept, of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107, USA.
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68
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Plotnikov A, Zehorai E, Procaccia S, Seger R. The MAPK cascades: signaling components, nuclear roles and mechanisms of nuclear translocation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1619-33. [PMID: 21167873 DOI: 10.1016/j.bbamcr.2010.12.012] [Citation(s) in RCA: 624] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 12/02/2010] [Accepted: 12/08/2010] [Indexed: 12/15/2022]
Abstract
The MAPK cascades are central signaling pathways that regulate a wide variety of stimulated cellular processes, including proliferation, differentiation, apoptosis and stress response. Therefore, dysregulation, or improper functioning of these cascades, is involved in the induction and progression of diseases such as cancer, diabetes, autoimmune diseases, and developmental abnormalities. Many of these physiological, and pathological functions are mediated by MAPK-dependent transcription of various regulatory genes. In order to induce transcription and the consequent functions, the signals transmitted via the cascades need to enter the nucleus, where they may modulate the activity of transcription factors and chromatin remodeling enzymes. In this review, we briefly cover the composition of the MAPK cascades, as well as their physiological and pathological functions. We describe, in more detail, many of the important nuclear activities of the MAPK cascades, and we elaborate on the mechanisms of ERK1/2 translocation into the nucleus, including the identification of their nuclear translocation sequence (NTS) binding to the shuttling protein importin7. Overall, the nuclear translocation of signaling components may emerge as an important regulatory layer in the induction of cellular processes, and therefore, may serve as targets for therapeutic intervention in signaling-related diseases such as cancer and diabetes. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
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Affiliation(s)
- Alexander Plotnikov
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Isreal
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69
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Nakamura K, Johnson GL. Activity assays for extracellular signal-regulated kinase 5. Methods Mol Biol 2010; 661:91-106. [PMID: 20811978 DOI: 10.1007/978-1-60761-795-2_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Extracellular signal-regulated kinase 5 (ERK5) is also known as big MAPK (BMK1) or MAPK7. ERK5 is 115 kDa in mass and therefore larger than the other MAPKs such as ERK1/2, JNK, and p38. Like other MAPKs, ERK5 is ubiquitously expressed in mammalian cells and is part of a three kinase cascade involving a MAPK kinase (MEK5) and MAPK kinase kinase (primarily MEKK2 and MEKK3). ERK5 is important for proliferative responses to growth factors like epidermal growth factor and stress responses such as hyperosmolarity. Upon stimulation, ERK5 rapidly translocates to the nucleus for the control of transcription. ERK5 is also critical for maintenance of vascular integrity and endothelial cell survival. In this chapter, we define methods used to measure the activation of ERK5 using different biochemical and cell-based assays.
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Affiliation(s)
- Kazuhiro Nakamura
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
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70
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Alternative ERK5 regulation by phosphorylation during the cell cycle. Cell Signal 2010; 22:1829-37. [DOI: 10.1016/j.cellsig.2010.07.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 07/06/2010] [Accepted: 07/13/2010] [Indexed: 02/01/2023]
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71
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DÍaz-RodrÍguez E, Pandiella A. Multisite phosphorylation of Erk5 in mitosis. J Cell Sci 2010; 123:3146-56. [DOI: 10.1242/jcs.070516] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The MAP kinase Erk5 plays important roles in cellular proliferation, and has recently been implicated in the regulation of mitosis. The classic pathway of Erk5 activation involves dual phosphorylation at its TEY microdomain by the upstream regulating kinase MEK5. Here we describe a second pathway that controls Erk5 phosphorylation. This pathway is activated in mitotic cells and involves kinase activities distinct from MEK5. Studies aimed at identifying these kinases suggested that CDK1 activity is required to sustain Erk5 phosphorylation in mitosis, as treatment with RO3306, a CDK1 inhibitor, reversed mitotic phosphorylation of Erk5. Moreover, CDK1 co-precipitated with Erk5 in mitotic cells. The mitotic phosphorylation of Erk5 occurs at multiple sites located at its unique C-terminal region, within an Erk5 subdomain that has formerly been implicated in the control of the subcellular location of Erk5. Furthermore, molecular studies indicated that phosphorylation at these sites may participate in the control of the transit of Erk5 between the cytosol and the nucleus, in addition to regulating its transcriptional activity. Together, our results demonstrate the existence of a second Erk5 phosphorylation pathway, that is activated in mitosis, and that may participate in the regulation of Erk5 functions.
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Affiliation(s)
- Elena DÍaz-RodrÍguez
- Instituto de BiologÍa Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, Campus Miguel de Unamuno, 37007-Salamanca, Spain
| | - Atanasio Pandiella
- Instituto de BiologÍa Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, Campus Miguel de Unamuno, 37007-Salamanca, Spain
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72
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Zhao Z, Wang W, Geng J, Wang L, Su G, Zhang Y, Ge Z, Kang W. Protein kinase C epsilon-dependent extracellular signal-regulated kinase 5 phosphorylation and nuclear translocation involved in cardiomyocyte hypertrophy with angiotensin II stimulation. J Cell Biochem 2010; 109:653-62. [PMID: 20052676 DOI: 10.1002/jcb.22441] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Angiotensin II (Ang II) plays a critical role in hypertrophy of cardiomyocytes; however, the molecular mechanism, especially the signaling cascades, in cardiomyocytes remains unclear. In the present study, we examined the mechanism of Ang II in hypertrophy of cardiomyocytes. Ang II rapidly stimulated phosphorylation of protein kinase C epsilon (PKCepsilon) in a time- and dose-dependent manner via Ang II receptor-1 (AT(1)). Furthermore, Ang II-induced extracellular signal-regulated kinase 5 (ERK5) phosphorylation and translocation was mediated through a signal pathway that involves AT(1) and PKCepsilon, which resulted in transcriptional activation of myocyte enhancer factor-2C (MEF2C) and hypertrophy. Consequently, inhibiting PKCepsilon or ERK5 by small interfering RNA (siRNA) significantly attenuated Ang II-induced MEF2C activation and hypertrophy of rat cardiomyocytes. These data provide evidence that PKCepsilon-dependent ERK5 phosphorylation and nucleocytoplasmic traffic mediates Ang II-induced MEF2C activation and cardiomyocyte hypertrophy. PKCepsilon and ERK5 may be potential targets in the treatment of pathological vascular hypertrophy associated with the enhanced renin-angiotensin system.
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Affiliation(s)
- Zhuo Zhao
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Shandong, PR China
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73
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Abstract
ERK5 (extracellular-signal-regulated kinase 5), also termed BMK1 [big MAPK1 (mitogen-activated protein kinase 1)], is the most recently discovered member of the MAPK family. It is expressed in a variety of tissues and is activated by a range of growth factors, cytokines and cellular stresses. Targeted deletion of Erk5 in mice has revealed that the ERK5 signalling cascade is critical for normal cardiovascular development and vascular integrity. In vitro studies have revealed that in endothelial cells, ERK5 is required for preventing apoptosis, mediating shear-stress signalling, regulating hypoxia, tumour angiogenesis and cell migration. This review focuses on our current understanding of the role of ERK5 in regulating endothelial cell function.
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74
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Carter EJ, Cosgrove RA, Gonzalez I, Eisemann JH, Lovett FA, Cobb LJ, Pell JM. MEK5 and ERK5 are mediators of the pro-myogenic actions of IGF-2. J Cell Sci 2009; 122:3104-12. [PMID: 19654213 DOI: 10.1242/jcs.045757] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the differentiation of muscle satellite cells, committed myoblasts respond to specific signalling cues by exiting the cell cycle, migrating, aligning, expressing muscle-specific genes and finally fusing to form multinucleated myotubes. The predominant foetal growth factor, IGF-2, initiates important signals in myogenesis. The aim of this study was to investigate whether ERK5 and its upstream MKK activator, MEK5, were important in the pro-myogenic actions of IGF-2. ERK5 protein levels, specific phosphorylation and kinase activity increased in differentiating C2 myoblasts. ERK5-GFP translocated from the cytoplasm to the nucleus after activation by upstream MEK5, whereas phospho-acceptor site mutated (dominant-negative) ERK5AEF-GFP remained cytoplasmic. Exogenous IGF-2 increased MHC levels, myogenic E box promoter-reporter activity, ERK5 phosphorylation and kinase activity, and rapidly induced nuclear localisation of ERK5. Transfection with antisense Igf2 decreased markers of myogenesis, and reduced ERK5 phosphorylation, kinase and transactivation activity. These negative effects of antisense Igf2 were rescued by constitutively active MEK5, whereas transfection of myoblasts with dominant-negative MEK5 blocked the pro-myogenic action of IGF-2. Our findings suggest that the MEK5-ERK5 pathway is a novel key mediator of IGF-2 action in myoblast differentiation.
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Affiliation(s)
- Emma J Carter
- Molecular Signalling, The Babraham Institute, Babraham Research Campus, Cambridge, UK
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75
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Sawhney RS, Liu W, Brattain MG. A novel role of ERK5 in integrin-mediated cell adhesion and motility in cancer cells via Fak signaling. J Cell Physiol 2009; 219:152-61. [PMID: 19089993 DOI: 10.1002/jcp.21662] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In metastatic cancer, high expression levels of vitronectin (VN) receptors (integrins), FAK, and ERK5 are reported. We hypothesized that integrin-mediated ERK5 activation via FAK may play a pivotal role in cell adhesion, motility, and metastasis. ERK5 and FAK phosphorylation when metastatic MDA-MB-231 and PC-3 cells were plated on VN was enhanced. Further experiments showed co-immunoprecipitation of integrins beta1, alpha V beta 3, or alpha V beta 5 with ERK5 and FAK. To gain better insight into the mechanism of ERK5, FAK, and VN receptors in cell adhesion and motility, we performed loss-of-function experiments using integrin blocking antibodies, and specific mutants of FAK and ERK5. Ectopic expression of dominant negative ERK5/AEF decreased ERK5 and FAK (Y397) phosphorylation, cell adhesion, and haptotactic motility (micromotion) on VN. Additionally, DN FAK expression attenuated ERK5 phosphorylation, cell adhesion, and motility. This study documents the novel finding that in breast and prostate cancer cells, ERK5 is a critical target of FAK in cell adhesion signaling. Using different cancer cells, our experiments unveil a novel mechanism by which VN receptors and FAK could promote cancer metastasis via ERK5 activation.
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Affiliation(s)
- Rajinder S Sawhney
- Department of Pharmacology & Toxicology, SUNY at Buffalo, Buffalo, New York, USA.
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76
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Boutros T, Chevet E, Metrakos P. Mitogen-activated protein (MAP) kinase/MAP kinase phosphatase regulation: roles in cell growth, death, and cancer. Pharmacol Rev 2009; 60:261-310. [PMID: 18922965 DOI: 10.1124/pr.107.00106] [Citation(s) in RCA: 438] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mitogen-activated protein kinase dual-specificity phosphatase-1 (also called MKP-1, DUSP1, ERP, CL100, HVH1, PTPN10, and 3CH134) is a member of the threonine-tyrosine dual-specificity phosphatases, one of more than 100 protein tyrosine phosphatases. It was first identified approximately 20 years ago, and since that time extensive investigations into both mkp-1 mRNA and protein regulation and function in different cells, tissues, and organs have been conducted. However, no general review on the topic of MKP-1 exists. As the subject matter pertaining to MKP-1 encompasses many branches of the biomedical field, we focus on the role of this protein in cancer development and progression, highlighting the potential role of the mitogen-activated protein kinase (MAPK) family. Section II of this article elucidates the MAPK family cross-talk. Section III reviews the structure of the mkp-1 encoding gene, and the known mechanisms regulating the expression and activity of the protein. Section IV is an overview of the MAPK-specific dual-specificity phosphatases and their role in cancer. In sections V and VI, mkp-1 mRNA and protein are examined in relation to cancer biology, therapeutics, and clinical studies, including a discussion of the potential role of the MAPK family. We conclude by proposing an integrated scheme for MKP-1 and MAPK in cancer.
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Affiliation(s)
- Tarek Boutros
- Department of Surgery, Royal Victoria Hospital, McGill University, 687 Pine Ave. W., Montreal, QC H3A1A1, Canada.
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77
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Du JX, Bialkowska AB, McConnell BB, Yang VW. SUMOylation regulates nuclear localization of Krüppel-like factor 5. J Biol Chem 2008; 283:31991-2002. [PMID: 18782761 DOI: 10.1074/jbc.m803612200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
SUMOylation is a form of post-translational modification shown to control nuclear transport. Krüppel-like factor 5 (KLF5) is an important mediator of cell proliferation and is primarily localized to the nucleus. Here we show that mouse KLF5 is SUMOylated at lysine residues 151 and 202. Mutation of these two lysines or two conserved nearby glutamates results in the loss of SUMOylation and increased cytoplasmic distribution of KLF5, suggesting that SUMOylation enhances nuclear localization of KLF5. Lysine 151 is adjacent to a nuclear export signal (NES) that resembles a consensus NES. The NES in KLF5 directs a fused green fluorescence protein to the cytoplasm, binds the nuclear export receptor CRM1, and is inhibited by leptomycin and site-directed mutagenesis. SUMOylation facilitates nuclear localization of KLF5 by inhibiting this NES activity, and enhances the ability of KLF5 to stimulate anchorage-independent growth of HCT116 colon cancer cells. A survey of proteins whose nuclear localization is regulated by SUMOylation reveals that SUMOylation sites are frequently located in close proximity to NESs. A relatively common mechanism for SUMOylation to regulate nucleocytoplasmic transport may lie in the interplay between neighboring NES and SUMOylation motifs.
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Affiliation(s)
- James X Du
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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78
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Integration of protein kinases mTOR and extracellular signal-regulated kinase 5 in regulating nucleocytoplasmic localization of NFATc4. Mol Cell Biol 2008; 28:3489-501. [PMID: 18347059 DOI: 10.1128/mcb.01847-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The target of rapamycin (TOR) signaling regulates the nucleocytoplasmic shuttling of transcription factors in yeast. Whether the mammalian counterpart of TOR (mTOR) also regulates nucleocytoplasmic shuttling is not known. Using a phospho-specific monoclonal antibody, we demonstrate that mTOR phosphorylates Ser(168,170) of endogenous NFATc4, which are conserved gate-keeping Ser residues that control NFAT subcellular distribution. The mTOR acts as a basal kinase during the resting state to maintain NFATc4 in the cytosol. Inactivation and nuclear export of NFATc4 are mediated by rephosphorylation of Ser(168,170), which can be a nuclear event. Kinetic analyses demonstrate that rephosphorylation of Ser(168,170) of endogenous NFATc4 is mediated by mTOR and, surprisingly, by extracellular signal-regulated kinase 5 (ERK5) mitogen-activated protein kinase as well. Ablation of ERK5 in the Erk5(-/-) cells ascertains defects in NFATc4 rephosphorylation and nucleocytoplasmic shuttling. In addition, phosphorylation of NFATc4 by ERK5 primes subsequent phosphorylation mediated by CK1alpha. These results demonstrate that distinct protein kinases are integrated to phosphorylate the gate-keeping residues Ser(168,170) of NFATc4, to regulate subcellular distribution. These data also expand the repertoire of physiological substrates of mTOR and ERK5.
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79
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McCracken SRC, Ramsay A, Heer R, Mathers ME, Jenkins BL, Edwards J, Robson CN, Marquez R, Cohen P, Leung HY. Aberrant expression of extracellular signal-regulated kinase 5 in human prostate cancer. Oncogene 2007; 27:2978-88. [PMID: 18071319 DOI: 10.1038/sj.onc.1210963] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Abnormal intracellular signaling contributes to carcinogenesis and may represent novel therapeutic targets. mitogen/extracellular signal-regulated kinase kinase-5 (MEK5) overexpression is associated with aggressive prostate cancer. In this study, we examined the role of extracellular signal-regulated kinase (ERK5, an MAPK and specific substrate for MEK5) in prostate cancer. ERK5 immunoreactivity was significantly upregulated in high-grade prostate cancer when compared to benign prostatic hyperplasia (P<0.0001). Increased ERK5 cytoplasmic signals correlated closely with Gleason sum score (P<0.0001), bony metastases (P=0.0044) and locally advanced disease at diagnosis (P=0.0023), with a weak association with shorter disease-specific survival (P=0.036). A subgroup of patients showed strong nuclear ERK5 localization, which correlated with poor disease-specific survival and, on multivariant analysis, was an independent prognostic factor (P<0.0001). Analysis of ERK5 expression in matched tumor pairs (before and after hormone relapse, n=26) revealed ERK5 nuclear expression was significantly associated with hormone-insensitive disease (P=0.0078). Similarly, ERK5 protein expression was increased in an androgen-independent LNCaP subline. We obtained the following in vitro and in vivo evidence to support the above expression data: (1) cotransfection of ERK5wt and MEK5D constructs in PC3 cells results in predominant ERK5 nuclear localization, similar to that observed in aggressive clinical disease; (2) ERK5-overexpressing PC3 cells have enhanced proliferative, migrative and invasive capabilities in vitro (P<0.0001), and were dramatically more efficient in forming tumors, with a shorter mean time for tumors to reach a critical volume of 1000 mm(3), in vivo (P<0.0001); (3) the MEK1 inhibitor, PD184352, blocking ERK1/2 activation at low dose, did not suppress proliferation but did significantly decrease proliferation at a higher dose required to inhibit ERK5 activation. Taken together, our results establish the potential importance of ERK5 in aggressive prostate cancer.
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Affiliation(s)
- S R C McCracken
- Urology Research Group, Northern Institute for Cancer Research, University of Newcastle, Tyne and Wear, UK
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80
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Morimoto H, Kondoh K, Nishimoto S, Terasawa K, Nishida E. Activation of a C-terminal transcriptional activation domain of ERK5 by autophosphorylation. J Biol Chem 2007; 282:35449-56. [PMID: 17928297 DOI: 10.1074/jbc.m704079200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ERK5 plays a crucial role in many biological processes by regulating transcription. ERK5 has a large C-terminal-half that contains a transcriptional activation domain. However, it has remained unclear how its transcriptional activation activity is regulated. Here, we show that the activated kinase activity of ERK5 is required for the C-terminal-half to enhance the AP-1 activity, and that the activated ERK5 undergoes autophosphorylation on its most C-terminal region. Changing these phosphorylatable threonine and serine residues to unphosphorylatable alanines significantly reduces the transcriptional activation activity of ERK5. Moreover, phosphomimetic mutants of the C-terminal-half of ERK5 without an N-terminal kinase domain are shown to be able to enhance the AP-1 activity in fibroblastic cells. These results reveal the role of the stimulus-induced ERK5 autophosphorylation in regulation of gene expression.
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Affiliation(s)
- Hiroko Morimoto
- Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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81
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Abstract
The mitogen-activated protein kinases (MAPKs) are a family of serine/threonine kinases that play an essential role in signal transduction by modulating gene transcription in the nucleus in response to changes in the cellular environment. They include the extracellular signal-regulated protein kinases (ERK1 and ERK2); c-Jun N-terminal kinases (JNK1, JNK2, JNK3); p38s (p38alpha, p38beta, p38gamma, p38delta) and ERK5. The molecular events in which MAPKs function can be separated in discrete and yet interrelated steps: activation of the MAPK by their upstream kinases, changes in the subcellular localization of MAPKs, and recognition, binding and phosphorylation of MAPK downstream targets. The resulting pattern of gene expression will ultimately depend on the integration of the combinatorial signals provided by the temporal activation of each group of MAPKs. This review will focus on how the specificity of signal transmission by MAPKs is achieved by scaffolding molecules and by the presence of structural motifs in MAPKs that are dynamically regulated by phosphorylation and protein-protein interactions. We discuss also how MAPKs recognize and phosphorylate their target nuclear proteins, including transcription factors, co-activators and repressors and chromatin-remodeling molecules, thereby affecting an intricate balance of nuclear regulatory molecules that ultimately control gene expression in response to environmental cues.
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Affiliation(s)
- A G Turjanski
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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82
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Kim KY, Cosano IC, Levin DE, Molina M, Martín H. Dissecting the transcriptional activation function of the cell wall integrity MAP kinase. Yeast 2007; 24:335-42. [PMID: 17397108 DOI: 10.1002/yea.1475] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The cell wall integrity signalling MAP kinase of Saccharomyces cerevisiae, Slt2p/Mpk1p, is activated in response to cell wall stress. Slt2 and its mammalian orthologue ERK5 are unusual among MAP kinases, in that they possess the ability to activate transcription of a GAL1-lacZ reporter when fused to the DNA-binding domain of the Gal4 transcription factor. In this study, we demonstrate that transcriptional activation of a Gal4-Slt2p fusion is responsive to cell wall stress and requires phosphorylation of Slt2p. We identify two neighbouring but separable transcription activation domains within the C-terminal half of Slt2p. Additionally, we present data suggesting that intramolecular interactions controlled by phosphorylation of Slt2p regulate the function of these domains, which are masked by the N-terminal catalytic domain under inactive conditions. Finally, we demonstrate that Slt2p self-associates, probably through a glutamine-rich region within the C-terminal half of the protein.
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Affiliation(s)
- Ki-Young Kim
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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83
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Piper PW, Truman AW, Millson SH, Nuttall J. Hsp90 chaperone control over transcriptional regulation by the yeast Slt2(Mpk1)p and human ERK5 mitogen-activated protein kinases (MAPKs). Biochem Soc Trans 2007; 34:783-5. [PMID: 17052197 DOI: 10.1042/bst0340783] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cell integrity MAPK (mitogen-activated protein kinase) function can be provided in yeast cells by either the native Slt2(Mpk1)p of yeast or by a heterologously expressed human ERK5 (extracellular-signal-regulated kinase 5). Both of these MAPKs need the Hsp90 (heat-shock protein 90) chaperone for their activation, so that when Hsp90 function is compromised their activities are low. This, in turn, affects the capacity of these MAPKs to control the transcription factors that regulate cell integrity genes.
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Affiliation(s)
- P W Piper
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
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84
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Garaude J, Cherni S, Kaminski S, Delepine E, Chable-Bessia C, Benkirane M, Borges J, Pandiella A, Iñiguez MA, Fresno M, Hipskind RA, Villalba M. ERK5 Activates NF-κB in Leukemic T Cells and Is Essential for Their Growth In Vivo. THE JOURNAL OF IMMUNOLOGY 2006; 177:7607-17. [PMID: 17114430 DOI: 10.4049/jimmunol.177.11.7607] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
MAPK cascades play a central role in the cellular response to the environment. The pathway involving the MAPK ERK5 mediates growth factor- and stress-induced intracellular signaling that controls proliferation or survival depending upon the cell context. In this study, we show that reducing ERK5 levels with a specific small hairpin RNA 5 (shERK5) reduced cell viability, sensitized cells to death receptor-induced apoptosis, and blocked the palliative effects of phorbol ester in anti-Fas Ab-treated cells. shERK5 decreased nuclear accumulation of the NF-kappaB p65 subunit, and conversely, ectopic activation of ERK5 led to constitutive nuclear localization of p65 and increased its ability to trans activate specific reporter genes. Finally, the T lymphoma cell line EL-4, upon expression of shERK5, proliferated in vitro, but failed to induce s.c. tumors in mice. Our results suggest that ERK5 is essential for survival of leukemic T cells in vivo, and thus represents a promising target for therapeutic intervention in this type of malignancy.
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Affiliation(s)
- Johan Garaude
- Institut de Génétique Moléculaire de Montpellier, Centre National de la Recherche Scientifique-Unité Mixte de Recherche 5535, IFR 122, 1919 Route de Mende, 34293 Montpellier, France
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85
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Nishimoto S, Nishida E. MAPK signalling: ERK5 versus ERK1/2. EMBO Rep 2006; 7:782-6. [PMID: 16880823 PMCID: PMC1525153 DOI: 10.1038/sj.embor.7400755] [Citation(s) in RCA: 326] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 06/19/2006] [Indexed: 12/16/2022] Open
Abstract
Extracellular-signal-regulated kinase 5 (ERK5) is a member of the mitogen-activated protein kinase (MAPK) family and, similar to ERK1/2, has the Thr-Glu-Tyr (TEY) activation motif. Both ERK5 and ERK1/2 are activated by growth factors and have an important role in the regulation of cell proliferation and cell differentiation. Moreover, both the ERK5 and the ERK1/2 pathways are sensitive to PD98059 and U0126, which are two well-known inhibitors of the ERK pathway. Despite these similarities, recent studies have revealed distinctive features of the ERK5 pathway: ERK5 has a key role in cardiovascular development and neural differentiation; ERK5 nuclear translocation is controlled by its own nuclear localizing and nuclear export activities; and the carboxy-terminal half of ERK5, which follows its kinase catalytic domain, has a unique function.
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Affiliation(s)
- Satoko Nishimoto
- Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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86
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Truman AW, Millson SH, Nuttall JM, King V, Mollapour M, Prodromou C, Pearl LH, Piper PW. Expressed in the yeast Saccharomyces cerevisiae, human ERK5 is a client of the Hsp90 chaperone that complements loss of the Slt2p (Mpk1p) cell integrity stress-activated protein kinase. EUKARYOTIC CELL 2006; 5:1914-24. [PMID: 16950928 PMCID: PMC1694803 DOI: 10.1128/ec.00263-06] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ERK5 is a mitogen-activated protein (MAP) kinase regulated in human cells by diverse mitogens and stresses but also suspected of mediating the effects of a number of oncogenes. Its expression in the slt2Delta Saccharomyces cerevisiae mutant rescued several of the phenotypes caused by the lack of Slt2p (Mpk1p) cell integrity MAP kinase. ERK5 is able to provide this cell integrity MAP kinase function in yeast, as it is activated by the cell integrity signaling cascade that normally activates Slt2p and, in its active form, able to stimulate at least one key Slt2p target (Rlm1p, the major transcriptional regulator of cell wall genes). In vitro ERK5 kinase activity was abolished by Hsp90 inhibition. ERK5 activity in vivo was also lost in a strain that expresses a mutant Hsp90 chaperone. Therefore, human ERK5 expressed in yeast is an Hsp90 client, despite the widely held belief that the protein kinases of the MAP kinase class are non-Hsp90-dependent activities. Two-hybrid and protein binding studies revealed that strong association of Hsp90 with ERK5 requires the dual phosphorylation of the TEY motif in the MAP kinase activation loop. These phosphorylations, at positions adjacent to the Hsp90-binding surface recently identified for a number of protein kinases, may cause a localized rearrangement of this MAP kinase region that leads to creation of the Hsp90-binding surface. Complementation of the slt2Delta yeast defect by ERK5 expression establishes a new tool with which to screen for novel agonists and antagonists of ERK5 signaling as well as for isolating mutant forms of ERK5.
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Affiliation(s)
- Andrew W Truman
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom
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87
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Abstract
Sequential activation of protein kinases within the mitogen-activated protein kinase (MAPK) cascades is a common mechanism of signal transduction in many cellular processes. Four such cascades have been elucidated thus far, and named according to their MAPK tier component as the ERK1/2, JNK, p38MAPK, and ERK5 cascades. These cascades cooperate in transmitting various extracellular signals, and thus control cellular processes such as proliferation, differentiation, development, stress response, and apoptosis. Here we describe the classic ERK1/2 cascade, and concentrate mainly on the properties of MEK1/2 and ERK1/2, including their mode of regulation and their role in various cellular processes and in oncogenesis. This cascade may serve as a prototype of the other MAPK cascades, and the study of this cascade is likely to contribute to the understanding of mitogenic and other processes in many cell lines and tissues.
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Affiliation(s)
- Hadara Rubinfeld
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel
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88
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Wang X, Finegan KG, Robinson AC, Knowles L, Khosravi-Far R, Hinchliffe KA, Boot-Handford RP, Tournier C. Activation of extracellular signal-regulated protein kinase 5 downregulates FasL upon osmotic stress. Cell Death Differ 2006; 13:2099-108. [PMID: 16710360 DOI: 10.1038/sj.cdd.4401969] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Extracellular signal-regulated protein kinase (ERK) 5 is a mitogen-activated protein kinase (MAPK) that is activated by dual phosphorylation via a unique MAPK/ERK kinase 5, MEK5. The physiological importance of this signaling cascade is underscored by the early embryonic death caused by the targeted deletion of the erk5 or the mek5 genes in mice. Here, we have found that ERK5 is required for mediating the survival of fibroblasts under basal conditions and in response to sorbitol treatment. Increased Fas ligand (FasL) expression acts as a positive feedback loop to enhance apoptosis of ERK5- or MEK5-deficient cells under conditions of osmotic stress. Compared to wild-type cells, erk5-/- and mek5-/- fibroblasts treated with sorbitol display a reduced protein kinase B (PKB) activity associated with increased Forkhead box O3a (Foxo3a) activity. Based on these results, we conclude that the ERK5 signaling pathway promotes cell survival by downregulating FasL expression via a mechanism that implicates PKB-dependent inhibition of Foxo3a downstream of phosphoinositide 3 kinase.
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Affiliation(s)
- X Wang
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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89
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Kondoh K, Terasawa K, Morimoto H, Nishida E. Regulation of nuclear translocation of extracellular signal-regulated kinase 5 by active nuclear import and export mechanisms. Mol Cell Biol 2006; 26:1679-90. [PMID: 16478989 PMCID: PMC1430242 DOI: 10.1128/mcb.26.5.1679-1690.2006] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 09/09/2005] [Accepted: 12/05/2005] [Indexed: 11/20/2022] Open
Abstract
Extracellular signal-regulated kinase 5 (ERK5), a member of the mitogen-activated protein kinase family, plays an important role in growth factor signaling to the nucleus. However, molecular mechanisms regulating subcellular localization of ERK5 have remained unclear. Here, we show that nucleocytoplasmic shuttling of ERK5 is regulated by a bipartite nuclear localization signal-dependent nuclear import mechanism and a CRM1-dependent nuclear export mechanism. Our results show that the N-terminal half of ERK5 binds to the C-terminal half and that this binding is necessary for nuclear export of ERK5. They further show that the activating phosphorylation of ERK5 by MEK5 results in the dissociation of the binding between the N- and C-terminal halves and thus inhibits nuclear export of ERK5, causing its nuclear import. These results reveal the mechanism by which the activating phosphorylation of ERK5 induces its nuclear import and suggest a novel example of a phosphorylation-dependent control mechanism for nucleocytoplasmic shuttling of proteins.
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Affiliation(s)
- Kunio Kondoh
- Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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90
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Iavarone C, Acunzo M, Carlomagno F, Catania A, Melillo RM, Carlomagno SM, Santoro M, Chiariello M. Activation of the Erk8 mitogen-activated protein (MAP) kinase by RET/PTC3, a constitutively active form of the RET proto-oncogene. J Biol Chem 2006; 281:10567-76. [PMID: 16484222 DOI: 10.1074/jbc.m513397200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitogen-activated protein (MAP) kinases have a central role in several biological functions, including cell adhesion and spreading, chemotaxis, cell cycle progression, differentiation, and apoptosis. Extracellular signal-regulated kinase 8 (Erk8) is a large MAP kinase whose activity is controlled by serum and the c-Src non-receptor tyrosine kinase. Here, we show that RET/PTC3, an activated form of the RET proto-oncogene, was able to activate Erk8, and we demonstrate that such MAP kinase participated in RET/PTC3-dependent stimulation of the c-jun promoter. By using RET/PTC3 molecules mutated in specific tyrosine autophosphorylation sites, we characterized Tyr(981), a known binding site for c-Src, as a major determinant of RET/PTC3-induced Erk8 activation, although, surprisingly, the underlying mechanism did not strictly depend on the activity of Src. In contrast, we present evidence that RET/PTC3 acts on Erk8 through Tyr(981)-mediated activation of c-Abl. Furthermore, we localized the region responsible for the modulation of Erk8 activity by the RET/PTC3 and Abl oncogenes in the Erk8 C-terminal domain. Altogether, these results support a role for Erk8 as a novel effector of RET/PTC3 and, therefore, RET biological functions.
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Affiliation(s)
- Carlo Iavarone
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università degli Studi di Napoli Federico II, Via Pansini 5, 80131 Naples, Italy
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91
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Seyfried J, Wang X, Kharebava G, Tournier C. A novel mitogen-activated protein kinase docking site in the N terminus of MEK5alpha organizes the components of the extracellular signal-regulated kinase 5 signaling pathway. Mol Cell Biol 2005; 25:9820-8. [PMID: 16260599 PMCID: PMC1280269 DOI: 10.1128/mcb.25.22.9820-9828.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The alternative splicing of the mek5 gene gives rise to two isoforms. MEK5beta lacks an extended N terminus present in MEK5alpha. Comparison of their activities led us to identify a novel mitogen-activated protein kinase (MAPK) docking site in the N terminus of MEK5alpha that is distinct from the consensus motif identified in the other MAPK kinases. It consists of a cluster of acidic residues at position 61 and positions 63 to 66. The formation of the MEK5/extracellular signal-regulated kinase 5 (ERK5) complex is critical for MEK5 to activate ERK5, to increase transcription via MEF2, and to enhance cellular survival in response to osmotic stress. Certain mutations in the ERK5 docking site that prevent MEK5/ERK5 interaction also abrogate the ability of MEKK2 to bind and activate MEK5. However, the identification of MEK5alpha mutants with selective binding defect demonstrates that the MEK5/ERK5 interaction does not rely on the binding of MEK5alpha to MEKK2 via their respective PB1 domains. Altogether these results establish that the N terminus of MEK5alpha is critical for the specific organization of the components of the ERK5 signaling pathway.
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Affiliation(s)
- Jan Seyfried
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom
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92
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Abstract
The mitogen-activated protein kinase (MAPK) ERK5 plays an important role in mammary epithelial proliferation, endothelial cell survival and normal embryonic development. In nonhaematopoietic cells, mitogenic and stress signals activate the ERK5 cascade. Here, we investigated the role of the ERK5 pathway in T-cell activation and show that primary and leukaemic T cells express ERK5, whose activating phosphorylation is induced by antibodies against CD3 but not by phorbol myristate acetate treatment. ERK5 localized in the cytosol and nucleus in quiescent and activated T cells. In the latter, ERK5 phosphorylation was mainly observed in the nucleus. Selective activation of the ERK5 cascade by transfecting constitutively active MEK5 and wildtype ERK5 induced a reporter gene driven by the IL-2 promoter while barely affecting CD69 expression. These results suggest a new role for the ERK5 cascade in intracellular signalling in T cells.
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Affiliation(s)
- J Garaude
- Institut de Génétique Moléculaire de Montpellier, CNRS UMR5535, IFR 122, 34293 Montpellier cedex 5, France
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