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Maietta I, Viscusi E, Laudati S, Iannaci G, D'Antonio A, Melillo RM, Motti ML, De Falco V. Targeting the p90RSK/MDM2/p53 Pathway Is Effective in Blocking Tumors with Oncogenic Up-Regulation of the MAPK Pathway Such as Melanoma and Lung Cancer. Cells 2024; 13:1546. [PMID: 39329730 PMCID: PMC11430938 DOI: 10.3390/cells13181546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2024] [Revised: 09/05/2024] [Accepted: 09/11/2024] [Indexed: 09/28/2024] Open
Abstract
In most human tumors, the MAPK pathway is constitutively activated. Since p90RSK is downstream of MAPK, it is often hyperactive and capable of phosphorylating oncogenic substrates. We have previously shown that p90RSK phosphorylates MDM2 at S166, promoting p53 degradation in follicular thyroid carcinomas. Thus, the inhibition of p90RSK restores p53 expression, which in turn inhibits cell proliferation and promotes apoptosis. In the present study, we demonstrated that the p90RSK/MDM2/p53 pathway proved to be an excellent target in the therapy of tumors with MAPK hyperactivation. For this purpose, we selected p53wt melanoma, lung and medullary thyroid carcinoma cell lines with high activation of p90RSK. In these cell lines, we demonstrated that the p90RSK/MDM2/p53 pathway is implicated in the regulation of the cell cycle and apoptosis through p53-dependent transcriptional control of p21 and Bcl-2. Furthermore, with an immunohistochemical evaluation of primary melanomas and lung tumors, which exhibit highly activated p90RSK compared to corresponding normal tissue, we demonstrated that MDM2 stabilization was associated with p90RSK phosphorylation. The results indicate that p90RSK is able to control the proliferative rate and induction of apoptosis through the regulation of p53wt levels by stabilizing MDM2 in selected tumors with constitutively activated MAPKs, making p90RSK a new attractive target for anticancer therapy.
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Affiliation(s)
- Immacolata Maietta
- Institute of Endocrinology and Experimental Oncology (IEOS), National Research Council (CNR), Via S. Pansini 5, 80131 Naples, Italy
| | - Eleonora Viscusi
- U.O.C. Anatomia Patologica, P.O. Pellegrini ASL NA1 Centro, 80134 Naples, Italy
| | - Stefano Laudati
- U.O.C. Anatomia Patologica, Ospedale del Mare ASL NA1 Centro, 80147 Naples, Italy
| | - Giuseppe Iannaci
- U.O.C. Anatomia Patologica, P.O. Pellegrini ASL NA1 Centro, 80134 Naples, Italy
| | - Antonio D'Antonio
- U.O.C. Anatomia Patologica, Ospedale del Mare ASL NA1 Centro, 80147 Naples, Italy
| | - Rosa Marina Melillo
- Institute of Endocrinology and Experimental Oncology (IEOS), National Research Council (CNR), Via S. Pansini 5, 80131 Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy
| | - Maria Letizia Motti
- Department of Medical, Movement and Wellbeing Sciences, University of Naples Parthenope, 80133 Naples, Italy
| | - Valentina De Falco
- Institute of Endocrinology and Experimental Oncology (IEOS), National Research Council (CNR), Via S. Pansini 5, 80131 Naples, Italy
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2
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Lubomirov LT, Mantke R, Enzmann T, Metzler D, Korotkova T, Hescheler J, Pfitzer G, Grisk O. ROK and RSK2-kinase pathways differ between senescent human renal and mesenteric arteries. J Hypertens 2023; 41:1201-1214. [PMID: 37115907 DOI: 10.1097/hjh.0000000000003450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE Small arteries from different organs vary with regard to the mechanisms that regulate vasoconstriction. This study investigated the impact of advanced age on the regulation of vasoconstriction in isolated human small arteries from kidney cortex and periintestinal mesenteric tissue. METHODS Renal and mesenteric tissues were obtained from patients (mean age 71 ± 9 years) undergoing elective surgery. Furthermore, intrarenal and mesenteric arteries from young and aged mice were studied. Arteries were investigated by small vessel myography and western blot. RESULTS Human intrarenal arteries (h-RA) showed higher stretch-induced tone and higher reactivity to α 1 adrenergic receptor stimulation than human mesenteric arteries (h-MA). Rho-kinase (ROK) inhibition resulted in a greater decrease in Ca 2+ and depolarization-induced tone in h-RA than in h-MA. Basal and α 1 adrenergic receptor stimulation-induced phosphorylation of the regulatory light chain of myosin (MLC 20 ) was higher in h-RA than in h-MA. This was associated with higher ROK-dependent phosphorylation of the regulatory subunit of myosin light-chain-phosphatase (MLCP), MYPT1-T853. In h-RA phosphorylation of ribosomal S6-kinase II (RSK2-S227) was significantly higher than in h-MA. Stretch-induced tone and RSK2 phosphorylation was also higher in interlobar arteries (m-IAs) from aged mice than in respective vessels from young mice and in murine mesenteric arteries (m-MA) from both age groups. CONCLUSION Vasoconstriction in human intrarenal arteries shows a greater ROK-dependence than in mesenteric arteries. Activation of RSK2 may contribute to intrarenal artery tone dysregulation associated with aging. Compared with h-RA, h-MA undergo age-related remodeling leading to a reduction of the contractile response to α 1 adrenergic stimulation.
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Affiliation(s)
- Lubomir T Lubomirov
- Institute of Physiology, Brandenburg Medical School Theodor Fontane, Neuruppin
- Institute of Vegetative Physiology
- Research cluster, Molecular Mechanisms of Cardiovascular Diseases
| | - René Mantke
- General and Visceral Surgery Clinic
- Faculty of Health Brandenburg, Brandenburg Medical School Theodor Fontane, Neuruppin, Germany
| | - Thomas Enzmann
- Urology and Children Urology Clinic, University Clinics Brandenburg an der Havel
| | | | | | - Jürgen Hescheler
- Institute of Neurophysiology, Center of Physiology, University of Cologne, Cologne
| | | | - Olaf Grisk
- Institute of Physiology, Brandenburg Medical School Theodor Fontane, Neuruppin
- Research cluster, Molecular Mechanisms of Cardiovascular Diseases
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3
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Koutsougianni F, Alexopoulou D, Uvez A, Lamprianidou A, Sereti E, Tsimplouli C, Ilkay Armutak E, Dimas K. P90 ribosomal S6 kinases: A bona fide target for novel targeted anticancer therapies? Biochem Pharmacol 2023; 210:115488. [PMID: 36889445 DOI: 10.1016/j.bcp.2023.115488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023]
Abstract
The 90 kDa ribosomal S6 kinase (RSK) family of proteins is a group of highly conserved Ser/Thr kinases. They are downstream effectors of the Ras/ERK/MAPK signaling cascade. ERK1/2 activation directly results in the phosphorylation of RSKs, which further, through interaction with a variety of different downstream substrates, activate various signaling events. In this context, they have been shown to mediate diverse cellular processes like cell survival, growth, proliferation, EMT, invasion, and metastasis. Interestingly, increased expression of RSKs has also been demonstrated in various cancers, such as breast, prostate, and lung cancer. This review aims to present the most recent advances in the field of RSK signaling that have occurred, such as biological insights, function, and mechanisms associated with carcinogenesis. We additionally present and discuss the recent advances but also the limitations in the development of pharmacological inhibitors of RSKs, in the context of the use of these kinases as putative, more efficient targets for novel anticancer therapeutic approaches.
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Affiliation(s)
- Fani Koutsougianni
- Department of Pharmacology, Faculty of Medicine, Health Sciences School, University of Thessaly, Larissa, Greece
| | - Dimitra Alexopoulou
- Department of Pharmacology, Faculty of Medicine, Health Sciences School, University of Thessaly, Larissa, Greece
| | - Ayca Uvez
- Department of Histology and Embryology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, 34500 Istanbul, Turkey
| | - Andromachi Lamprianidou
- Department of Pharmacology, Faculty of Medicine, Health Sciences School, University of Thessaly, Larissa, Greece
| | - Evangelia Sereti
- Dept of Translational Medicine, Medical Faculty, Lund University and Center for Molecular Pathology, Skäne University Hospital, Jan Waldenströms gata 59, SE 205 02 Malmö, Sweden
| | - Chrisiida Tsimplouli
- Department of Pharmacology, Faculty of Medicine, Health Sciences School, University of Thessaly, Larissa, Greece
| | - Elif Ilkay Armutak
- Department of Histology and Embryology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, 34500 Istanbul, Turkey
| | - Konstantinos Dimas
- Department of Pharmacology, Faculty of Medicine, Health Sciences School, University of Thessaly, Larissa, Greece.
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4
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Fricke AL, Mühlhäuser WWD, Reimann L, Zimmermann JP, Reichenbach C, Knapp B, Peikert CD, Heberle AM, Faessler E, Schäuble S, Hahn U, Thedieck K, Radziwill G, Warscheid B. Phosphoproteomics Profiling Defines a Target Landscape of the Basophilic Protein Kinases AKT, S6K, and RSK in Skeletal Myotubes. J Proteome Res 2023; 22:768-789. [PMID: 36763541 DOI: 10.1021/acs.jproteome.2c00505] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Phosphorylation-dependent signal transduction plays an important role in regulating the functions and fate of skeletal muscle cells. Central players in the phospho-signaling network are the protein kinases AKT, S6K, and RSK as part of the PI3K-AKT-mTOR-S6K and RAF-MEK-ERK-RSK pathways. However, despite their functional importance, knowledge about their specific targets is incomplete because these kinases share the same basophilic substrate motif RxRxxp[ST]. To address this, we performed a multifaceted quantitative phosphoproteomics study of skeletal myotubes following kinase inhibition. Our data corroborate a cross talk between AKT and RAF, a negative feedback loop of RSK on ERK, and a putative connection between RSK and PI3K signaling. Altogether, we report a kinase target landscape containing 49 so far unknown target sites. AKT, S6K, and RSK phosphorylate numerous proteins involved in muscle development, integrity, and functions, and signaling converges on factors that are central for the skeletal muscle cytoskeleton. Whereas AKT controls insulin signaling and impinges on GTPase signaling, nuclear signaling is characteristic for RSK. Our data further support a role of RSK in glucose metabolism. Shared targets have functions in RNA maturation, stability, and translation, which suggests that these basophilic kinases establish an intricate signaling network to orchestrate and regulate processes involved in translation.
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Affiliation(s)
- Anna L Fricke
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Wignand W D Mühlhäuser
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Lena Reimann
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Johannes P Zimmermann
- Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Christa Reichenbach
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Knapp
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christian D Peikert
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Alexander M Heberle
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Erik Faessler
- Jena University Language & Information Engineering (JULIE) Lab, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Sascha Schäuble
- Jena University Language & Information Engineering (JULIE) Lab, Friedrich Schiller University Jena, 07743 Jena, Germany.,Systems Biology and Bioinformatics Unit, Leibniz Institute for Natural Product Research and Infection Biology─Leibniz-HKI, 07745 Jena, Germany
| | - Udo Hahn
- Jena University Language & Information Engineering (JULIE) Lab, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Kathrin Thedieck
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria.,Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands.,Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg 26129, Germany
| | - Gerald Radziwill
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
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5
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p90RSK Regulates p53 Pathway by MDM2 Phosphorylation in Thyroid Tumors. Cancers (Basel) 2022; 15:cancers15010121. [PMID: 36612117 PMCID: PMC9817759 DOI: 10.3390/cancers15010121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/10/2022] [Accepted: 12/21/2022] [Indexed: 12/28/2022] Open
Abstract
The expression level of the tumor suppressor p53 is controlled by the E3 ubiquitin ligase MDM2 with a regulatory feedback loop, which allows p53 to upregulate its inhibitor MDM2. In this manuscript we demonstrated that p90RSK binds and phosphorylates MDM2 on serine 166 both in vitro and in vivo by kinase assay, immunoblot, and co-immunoprecipitation assay; this phosphorylation increases the stability of MDM2 which in turn binds p53, ubiquitinating it and promoting its degradation by proteasome. A pharmacological inhibitor of p90RSK, BI-D1870, decreases MDM2 phosphorylation, and restores p53 function, which in turn transcriptionally increases the expression of cell cycle inhibitor p21 and of pro-apoptotic protein Bax and downregulates the anti-apoptotic protein Bcl-2, causing a block of cell proliferation, measured by a BrdU assay and growth curve, and promoting apoptosis, measured by a TUNEL assay. Finally, an immunohistochemistry evaluation of primary thyroid tumors, in which p90RSK is very active, confirms MDM2 stabilization mediated by p90RSK phosphorylation.
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6
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Cronin R, Brooke GN, Prischi F. The role of the p90 ribosomal S6 kinase family in prostate cancer progression and therapy resistance. Oncogene 2021; 40:3775-3785. [PMID: 33972681 PMCID: PMC8175238 DOI: 10.1038/s41388-021-01810-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/08/2021] [Accepted: 04/20/2021] [Indexed: 02/06/2023]
Abstract
Prostate cancer (PCa) is the second most commonly occurring cancer in men, with over a million new cases every year worldwide. Tumor growth and disease progression is mainly dependent on the Androgen Receptor (AR), a ligand dependent transcription factor. Standard PCa therapeutic treatments include androgen-deprivation therapy and AR signaling inhibitors. Despite being successful in controlling the disease in the majority of men, the high frequency of disease progression to aggressive and therapy resistant stages (termed castrate resistant prostate cancer) has led to the search for new therapeutic targets. The p90 ribosomal S6 kinase (RSK1-4) family is a group of highly conserved Ser/Thr kinases that holds promise as a novel target. RSKs are effector kinases that lay downstream of the Ras/Raf/MEK/ERK signaling pathway, and aberrant activation or expression of RSKs has been reported in several malignancies, including PCa. Despite their structural similarities, RSK isoforms have been shown to perform nonredundant functions and target a wide range of substrates involved in regulation of transcription and translation. In this article we review the roles of the RSKs in proliferation and motility, cell cycle control and therapy resistance in PCa, highlighting the possible interplay between RSKs and AR in mediating disease progression. In addition, we summarize the current advances in RSK inhibitor development and discuss their potential clinical benefits.
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Affiliation(s)
- Ryan Cronin
- School of Life Sciences, University of Essex, Colchester, UK
| | - Greg N Brooke
- School of Life Sciences, University of Essex, Colchester, UK.
| | - Filippo Prischi
- School of Life Sciences, University of Essex, Colchester, UK.
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7
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Cesaro L, Pinna LA. Prevalence and significance of the commonest phosphorylated motifs in the human proteome: a global analysis. Cell Mol Life Sci 2020; 77:5281-5298. [PMID: 32052090 PMCID: PMC11105107 DOI: 10.1007/s00018-020-03474-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/22/2020] [Accepted: 01/28/2020] [Indexed: 01/08/2023]
Abstract
Protein phosphorylation is the most frequent post-translational modification by which the properties of eukaryotic proteins can be reversibly modified. In humans, over 500 protein kinases generate a huge phosphoproteome including more than 200,000 individual phosphosites, a figure which is still continuously increasing. The in vivo selectivity of protein kinases is the outcome of a multifaceted and finely tuned process where numerous factors play an integrated role. To gain information about the actual contribution to this process of local features that reflect the interaction of the protein targets with the catalytic site of the kinases, the prevalence of the commonest motifs determining the consensus sequence of Ser/Thr-specific kinases has been examined in the whole human phosphoproteome and in the phosphoproteomes generated by a panel of the 47 most pleiotropic protein kinases. Our analysis shows that: (1) most phosphosites do conform to at least one of the motifs considered, with a substantial proportion conforming to two or more of them; (2) some motifs, with special reference to the one recognized by protein kinase CK2 (pS/pT-x-x-E/D) are very promiscuous, being abundantly represented also at the phosphosites of all the other protein kinases considered; (3) by contrast, other phosphorylated motifs, notably pS/pT-P, pS/pT-Q and pS-x-E, are more discriminatory and selective, being nearly absent in the phosphosites that are not attributable to certain categories of kinases. The information provided will prove helpful to make reliable inferences based on the manual inspection of individual phosphosites.
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Affiliation(s)
- Luca Cesaro
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy
| | - Lorenzo A Pinna
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy.
- CNR Institute of Neurosciences, Viale G. Colombo 3, 35131, Padova, Italy.
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8
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Uhrig RG, Schläpfer P, Roschitzki B, Hirsch-Hoffmann M, Gruissem W. Diurnal changes in concerted plant protein phosphorylation and acetylation in Arabidopsis organs and seedlings. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:176-194. [PMID: 30920011 DOI: 10.1111/tpj.14315] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 02/24/2019] [Accepted: 02/26/2019] [Indexed: 05/22/2023]
Abstract
Protein phosphorylation and acetylation are the two most abundant post-translational modifications (PTMs) that regulate protein functions in eukaryotes. In plants, these PTMs have been investigated individually; however, their co-occurrence and dynamics on proteins is currently unknown. Using Arabidopsis thaliana, we quantified changes in protein phosphorylation, acetylation and protein abundance in leaf rosettes, roots, flowers, siliques and seedlings at the end of day (ED) and at the end of night (EN). This identified 2549 phosphorylated and 909 acetylated proteins, of which 1724 phosphorylated and 536 acetylated proteins were also quantified for changes in PTM abundance between ED and EN. Using a sequential dual-PTM workflow, we identified significant PTM changes and intersections in these organs and plant developmental stages. In particular, cellular process-, pathway- and protein-level analyses reveal that the phosphoproteome and acetylome predominantly intersect at the pathway- and cellular process-level at ED versus EN. We found 134 proteins involved in core plant cell processes, such as light harvesting and photosynthesis, translation, metabolism and cellular transport, that were both phosphorylated and acetylated. Our results establish connections between PTM motifs, PTM catalyzing enzymes and putative substrate networks. We also identified PTM motifs for further characterization of the regulatory mechanisms that control cellular processes during the diurnal cycle in different Arabidopsis organs and seedlings. The sequential dual-PTM analysis expands our understanding of diurnal plant cell regulation by PTMs and provides a useful resource for future analyses, while emphasizing the importance of analyzing multiple PTMs simultaneously to elucidate when, where and how they are involved in plant cell regulation.
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Affiliation(s)
- R Glen Uhrig
- Institute of Molecular Plant Biology, Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Pascal Schläpfer
- Institute of Molecular Plant Biology, Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Bernd Roschitzki
- Functional Genomics Center, ETH Zurich, 8092, Zurich, Switzerland
| | - Matthias Hirsch-Hoffmann
- Institute of Molecular Plant Biology, Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Wilhelm Gruissem
- Institute of Molecular Plant Biology, Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, 40227, Taiwan
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9
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Samson SC, Elliott A, Mueller BD, Kim Y, Carney KR, Bergman JP, Blenis J, Mendoza MC. p90 ribosomal S6 kinase (RSK) phosphorylates myosin phosphatase and thereby controls edge dynamics during cell migration. J Biol Chem 2019; 294:10846-10862. [PMID: 31138649 PMCID: PMC6635457 DOI: 10.1074/jbc.ra119.007431] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 05/08/2019] [Indexed: 12/25/2022] Open
Abstract
Cell migration is essential to embryonic development, wound healing, and cancer cell dissemination. Cells move via leading-edge protrusion, substrate adhesion, and retraction of the cell's rear. The molecular mechanisms by which extracellular cues signal to the actomyosin cytoskeleton to control these motility mechanics are poorly understood. The growth factor-responsive and oncogenically activated protein extracellular signal-regulated kinase (ERK) promotes motility by signaling in actin polymerization-mediated edge protrusion. Using a combination of immunoblotting, co-immunoprecipitation, and myosin-binding experiments and cell migration assays, we show here that ERK also signals to the contractile machinery through its substrate, p90 ribosomal S6 kinase (RSK). We probed the signaling and migration dynamics of multiple mammalian cell lines and found that RSK phosphorylates myosin phosphatase–targeting subunit 1 (MYPT1) at Ser-507, which promotes an interaction of Rho kinase (ROCK) with MYPT1 and inhibits myosin targeting. We find that by inhibiting the myosin phosphatase, ERK and RSK promote myosin II–mediated tension for lamella expansion and optimal edge dynamics for cell migration. These findings suggest that ERK activity can coordinately amplify both protrusive and contractile forces for optimal cell motility.
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Affiliation(s)
- Shiela C Samson
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and
| | - Andrew Elliott
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and
| | - Brian D Mueller
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and
| | - Yung Kim
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and
| | - Keith R Carney
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and
| | - Jared P Bergman
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and
| | - John Blenis
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Michelle C Mendoza
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112 and; Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115.
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10
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Houles T, Roux PP. Defining the role of the RSK isoforms in cancer. Semin Cancer Biol 2017; 48:53-61. [PMID: 28476656 DOI: 10.1016/j.semcancer.2017.04.016] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/10/2017] [Accepted: 04/28/2017] [Indexed: 02/03/2023]
Abstract
The 90kDa ribosomal S6 kinase (RSK) family is a group of Ser/Thr protein kinases (RSK1-4) that function downstream of the Ras/mitogen-activated protein kinase (MAPK) signalling pathway. RSK regulates many substrates involved in cell survival, growth, and proliferation, and as such, deregulated RSK activity has been associated with multiple cancer types. RSK expression and activity are dysregulated in several malignancies, including breast, prostate, and lung cancer, and available evidence suggests that RSK may be a promising cancer therapeutic target. Current limitations include the lack of RSK inhibitors with suitable pharmacokinetics and selectivity toward particular isoforms. This review briefly describes the current knowledge on RSK activation and function, with a particular emphasis on RSK-dependent mechanisms associated with tumorigenesis and pharmacological inhibition.
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Affiliation(s)
- Thibault Houles
- Institute for Research in Immunology and Cancer (IRIC), Canada
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer (IRIC), Canada; Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.
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11
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Lim HC, Jou TS. Ras-activated RSK1 phosphorylates EBP50 to regulate its nuclear localization and promote cell proliferation. Oncotarget 2016; 7:10283-96. [PMID: 26862730 PMCID: PMC4891120 DOI: 10.18632/oncotarget.7184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/25/2016] [Indexed: 11/25/2022] Open
Abstract
Differential subcellular localization of EBP50 leads to its controversial role in cancer biology either as a tumor suppressor when it resides at the membrane periphery, or a tumor facilitator at the nucleus. However, the mechanism behind nuclear localization of EBP50 remains unclear. A RNA interference screening identified the downstream effector of the Ras-ERK cascade, RSK1, as the molecule unique for nuclear transport of EBP50. RSK1 binds to EBP50 and phosphorylates it at a conserved threonine residue at position 156 (T156) under the regulation of growth factor. Mutagenesis experiments confirmed the significance of T156 residue in nuclear localization of EBP50, cellular proliferation, and oncogenic transformation. Our study sheds light on a possible therapeutic strategy targeting at this aberrant nuclear expression of EBP50 without affecting the normal physiological function of EBP50 at other subcellular localization.
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Affiliation(s)
- Hooi Cheng Lim
- Graduate Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan
| | - Tzuu-Shuh Jou
- Graduate Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Clinical Medicine, National Taiwan University, Taipei, Taiwan
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12
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Elevated ERK/p90 ribosomal S6 kinase activity underlies audiogenic seizure susceptibility in fragile X mice. Proc Natl Acad Sci U S A 2016; 113:E6290-E6297. [PMID: 27663742 DOI: 10.1073/pnas.1610812113] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common heritable cause of intellectual disability and a leading genetic form of autism. The Fmr1 KO mouse, a model of FXS, exhibits elevated translation in the hippocampus and the cortex. ERK (extracellular signal-regulated kinase) and mTOR (mechanistic target of rapamycin) signaling regulate protein synthesis by activating downstream targets critical to translation initiation and elongation and are known to contribute to hippocampal defects in fragile X. Here we show that the effect of loss of fragile X mental retardation protein (FMRP) on these pathways is brain region specific. In contrast to the hippocampus, ERK (but not mTOR) signaling is elevated in the neocortex of fragile X mice. Phosphorylation of ribosomal protein S6, typically a downstream target of mTOR, is elevated in the neocortex, despite normal mTOR activity. This is significant in that S6 phosphorylation facilitates translation, correlates with neuronal activation, and is altered in neurodevelopmental disorders. We show that in fragile X mice, S6 is regulated by ERK via the "alternative" S6 kinase p90-ribosomal S6 kinase (RSK), as evidenced by the site of elevated phosphorylation and the finding that ERK inhibition corrects elevated RSK and S6 activity. These findings indicate that signaling networks are altered in the neocortex of fragile X mice such that S6 phosphorylation receives aberrant input from ERK/RSK. Importantly, an RSK inhibitor reduces susceptibility to audiogenic seizures in fragile X mice. Our findings identify RSK as a therapeutic target for fragile X and suggest the therapeutic potential of drugs for the treatment of FXS may vary in a brain-region-specific manner.
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Abstract
INTRODUCTION The p90 ribosomal S6 kinases (RSK) are a family of Ser/Thr protein kinases that are downstream effectors of MEK1/2-ERK1/2. Increased RSK activation is implicated in the etiology of multiple pathologies, including numerous types of cancers, cardiovascular disease, liver and lung fibrosis, and infections. AREAS COVERED The review summarizes the patent and scientific literature on small molecule modulators of RSK and their potential use as therapeutics. The patents were identified using World Intellectual Property Organization and United States Patent and Trademark Office databases. The compounds described are predominantly RSK inhibitors, but a RSK activator is also described. The majority of the inhibitors are not RSK-specific. EXPERT OPINION Based on the overwhelming evidence that RSK is involved in a number of diseases that have high mortalities it seems surprising that there are no RSK modulators that have pharmacokinetic properties suitable for in vivo use. MEK1/2 inhibitors are in the clinic, but the efficacy of these compounds appears to be limited by their side effects. We hypothesize that targeting the downstream effectors of MEK1/2, like RSK, are an untapped source of drug targets and that they will generate less side effects than MEK1/2 inhibitors because they regulate fewer effectors.
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Affiliation(s)
- Katarzyna A Ludwik
- a Department of Pathology, Microbiology & Immunology , Vanderbilt University , Nashville , TN , USA
| | - Deborah A Lannigan
- a Department of Pathology, Microbiology & Immunology , Vanderbilt University , Nashville , TN , USA.,b Department of Cancer Biology , Vanderbilt University , Nashville , TN , USA
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Li W, Avey D, Fu B, Wu JJ, Ma S, Liu X, Zhu F. Kaposi's Sarcoma-Associated Herpesvirus Inhibitor of cGAS (KicGAS), Encoded by ORF52, Is an Abundant Tegument Protein and Is Required for Production of Infectious Progeny Viruses. J Virol 2016; 90:5329-5342. [PMID: 27009954 PMCID: PMC4934757 DOI: 10.1128/jvi.02675-15] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 03/08/2016] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED Although Kaposi's sarcoma-associated herpesvirus (KSHV) ORF52 (also known as KSHV inhibitor of cGAS [KicGAS]) has been detected in purified virions, the roles of this protein during KSHV replication have not been characterized. Using specific monoclonal antibodies, we revealed that ORF52 displays true late gene expression kinetics and confirmed its cytoplasmic localization in both transfected and KSHV-infected cells. We demonstrated that ORF52 comigrates with other known virion proteins following sucrose gradient centrifugation. We also determined that ORF52 resides inside the viral envelope and remains partially associated with capsid when extracellular virions are treated with various detergents and/or salts. There results indicate that ORF52 is a tegument protein abundantly present in extracellular virions. To characterize the roles of ORF52 in the KSHV life cycle, we engineered a recombinant KSHV ORF52-null mutant virus and found that loss of ORF52 results in reduced virion production and a further defect in infectivity. Upon analysis of the virion composition of ORF52-null viral particles, we observed a decrease in the incorporation of ORF45, as well as other tegument proteins, suggesting that ORF52 is important for the packaging of other virion proteins. In summary, our results indicate that, in addition to its immune evasion function, KSHV ORF52 is required for the optimal production of infectious virions, likely due to its roles in virion assembly as a tegument protein. IMPORTANCE The tegument proteins of herpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), play key roles in the viral life cycle. Each of the three subfamilies of herpesviruses (alpha, beta, and gamma) encode unique tegument proteins with specialized functions. We recently found that one such gammaherpesvirus-specific protein, ORF52, has an important role in immune evasion during KSHV primary infection, through inhibition of the host cytosolic DNA sensing pathway. In this report, we further characterize ORF52 as a tegument protein with vital roles during KSHV lytic replication. We found that ORF52 is important for the production of infectious viral particles, likely through its role in virus assembly, a critical process for KSHV replication and pathogenesis. More comprehensive investigation of the functions of tegument proteins and their roles in viral replication may reveal novel targets for therapeutic interventions against KSHV-associated diseases.
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Affiliation(s)
- Wenwei Li
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Denis Avey
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Bishi Fu
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Jian-Jun Wu
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Siming Ma
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Xia Liu
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Fanxiu Zhu
- Department of Biological Science, Florida State University, Tallahassee, Florida, USA
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Phosphoproteomic Analysis of KSHV-Infected Cells Reveals Roles of ORF45-Activated RSK during Lytic Replication. PLoS Pathog 2015; 11:e1004993. [PMID: 26133373 PMCID: PMC4489790 DOI: 10.1371/journal.ppat.1004993] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/02/2015] [Indexed: 12/13/2022] Open
Abstract
Kaposi’s Sarcoma-Associated Herpesvirus (KSHV) is an oncogenic virus which has adapted unique mechanisms to modulate the cellular microenvironment of its human host. The pathogenesis of KSHV is intimately linked to its manipulation of cellular signaling pathways, including the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway. We have previously shown that KSHV ORF45 contributes to the sustained activation of both ERK and p90 ribosomal S6 kinase (RSK, a major functional mediator of ERK/MAPK signaling) during KSHV lytic replication. ORF45-activated RSK is required for optimal KSHV lytic gene expression and progeny virion production, though the underlying mechanisms downstream of this activation are still unclear. We hypothesized that the activation of RSK by ORF45 causes differential phosphorylation of cellular and viral substrates, affecting biological processes essential for efficient KSHV lytic replication. Accordingly, we observed widespread and significant differences in protein phosphorylation upon induction of lytic replication. Mass-spectrometry-based phosphoproteomic screening identified putative substrates of ORF45-activated RSK in KSHV-infected cells. Bioinformatic analyses revealed that nuclear proteins, including several transcriptional regulators, were overrepresented among these candidates. We validated the ORF45/RSK-dependent phosphorylation of several putative substrates by employing KSHV BAC mutagenesis, kinase inhibitor treatments, and/or CRISPR-mediated knockout of RSK in KSHV-infected cells. Furthermore, we assessed the consequences of knocking out these substrates on ORF45/RSK-dependent regulation of gene expression and KSHV progeny virion production. Finally, we show data to support that ORF45 regulates the translational efficiency of a subset of viral/cellular genes with complex secondary structure in their 5’ UTR. Altogether, these data shed light on the mechanisms by which KSHV ORF45 manipulates components of the host cell machinery via modulation of RSK activity. Thus, this study has important implications for the pathobiology of KSHV and other diseases in which RSK activity is dysregulated. Kaposi’s sarcoma-associated herpesvirus (KSHV) is a human tumor virus which hijacks the host signaling pathways in order to maintain persistent infection. We previously discovered that the KSHV protein ORF45 binds to and activates the cellular kinase RSK (p90 ribosomal S6 kinase), and that this activation is vital for optimal KSHV gene expression and virion production. Here, we performed a phosphoproteomic analysis of KSHV-infected cells to further characterize the specific substrates of ORF45-activated RSK. Bioinformatic analyses provided insights into the functional roles of these substrates. We verified the ORF45/RSK-dependent phosphorylation of a subset of these substrates by various means. Finally, we used genome editing to knock out RSK, as well as several cellular substrates identified by our screening, and characterized the consequent effect(s) on regulation of gene expression and virion production. Thus, this work further elucidates one of the key signaling nodes modulated by KSHV, and implicates ORF45-mediated activation of RSK in the regulation of viral and host gene expression during KSHV lytic replication.
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Martinez EC, Passariello CL, Li J, Matheson CJ, Dodge-Kafka K, Reigan P, Kapiloff MS. RSK3: A regulator of pathological cardiac remodeling. IUBMB Life 2015; 67:331-7. [PMID: 25988524 PMCID: PMC4449288 DOI: 10.1002/iub.1383] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/08/2015] [Indexed: 12/18/2022]
Abstract
The family of p90 ribosomal S6 kinases (RSKs) are pleiotropic effectors for extracellular signal-regulated kinase signaling pathways. Recently, RSK3 was shown to be important for pathological remodeling of the heart. Although cardiac myocyte hypertrophy can be compensatory for increased wall stress, in chronic heart diseases, this nonmitotic cell growth is usually associated with interstitial fibrosis, increased cell death, and decreased cardiac function. Although RSK3 is less abundant in the cardiac myocyte than other RSK family members, RSK3 appears to serve a unique role in cardiac myocyte stress responses. A potential mechanism conferring the unique function of RSK3 in the heart is anchoring by the scaffold protein muscle A-kinase anchoring protein β (mAKAPβ). Recent findings suggest that RSK3 should be considered as a therapeutic target for the prevention of heart failure, a clinical syndrome of major public health significance.
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Affiliation(s)
- Eliana C. Martinez
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Catherine L. Passariello
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Jinliang Li
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Christopher J. Matheson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, USA
| | - Kimberly Dodge-Kafka
- Calhoun Center for Cardiology, University of Connecticut Health Center, Farmington, CT, USA
| | - Philip Reigan
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, USA
| | - Michael S. Kapiloff
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
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Jung E, Cho JY, Park D, Kim MH, Park B, Lee SY, Lee J. Vegetable peptones increase production of type I collagen in human fibroblasts by inducing the RSK-CCAAT/enhancer binding protein-β phosphorylation pathway. Nutr Res 2015; 35:127-35. [PMID: 25464949 DOI: 10.1016/j.nutres.2014.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 10/20/2014] [Accepted: 10/22/2014] [Indexed: 02/08/2023]
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Kennedy JM, Fodil N, Torre S, Bongfen SE, Olivier JF, Leung V, Langlais D, Meunier C, Berghout J, Langat P, Schwartzentruber J, Majewski J, Lathrop M, Vidal SM, Gros P. CCDC88B is a novel regulator of maturation and effector functions of T cells during pathological inflammation. ACTA ACUST UNITED AC 2014; 211:2519-35. [PMID: 25403443 PMCID: PMC4267237 DOI: 10.1084/jem.20140455] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Kennedy et al. identify a mutation in coiled-coil domain containing protein 88b (Ccdc88b) that confers protection against lethal neuroinflammation during experimental cerebral malaria. CCDC88B is expressed in immune cells and regulates T cell maturation and effector functions. In humans, the CCDC88B gene maps to a locus associated with susceptibility to several inflammatory and autoimmune disorders. We used a genome-wide screen in mutagenized mice to identify genes which inactivation protects against lethal neuroinflammation during experimental cerebral malaria (ECM). We identified an ECM-protective mutation in coiled-coil domain containing protein 88b (Ccdc88b), a poorly annotated gene that is found expressed specifically in spleen, bone marrow, lymph nodes, and thymus. The CCDC88B protein is abundantly expressed in immune cells, including both CD4+ and CD8+ T lymphocytes, and in myeloid cells, and loss of CCDC88B protein expression has pleiotropic effects on T lymphocyte functions, including impaired maturation in vivo, significantly reduced activation, reduced cell division as well as impaired cytokine production (IFN-γ and TNF) in response to T cell receptor engagement, or to nonspecific stimuli in vitro, and during the course of P. berghei infection in vivo. This identifies CCDC88B as a novel and important regulator of T cell function. The human CCDC88B gene maps to the 11q13 locus that is associated with susceptibility to several inflammatory and auto-immune disorders. Our findings strongly suggest that CCDC88B is the morbid gene underlying the pleiotropic effect of the 11q13 locus on inflammation.
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Affiliation(s)
- James M Kennedy
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Nassima Fodil
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Sabrina Torre
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Silayuv E Bongfen
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Jean-Frédéric Olivier
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Vicki Leung
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - David Langlais
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Charles Meunier
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Joanne Berghout
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Pinky Langat
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Jeremy Schwartzentruber
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Jacek Majewski
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Mark Lathrop
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Silvia M Vidal
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Philippe Gros
- Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada Department of Biochemistry, Department of Human Genetics, McGill and Genome Quebec Innovation Center, Complex Traits Group, McGill University, Montreal, Quebec H3A 0G4, Canada
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Phosphoproteomic analysis identifies the tumor suppressor PDCD4 as a RSK substrate negatively regulated by 14-3-3. Proc Natl Acad Sci U S A 2014; 111:E2918-27. [PMID: 25002506 DOI: 10.1073/pnas.1405601111] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The Ras/MAPK signaling cascade regulates various biological functions, including cell growth and proliferation. As such, this pathway is frequently deregulated in several types of cancer, including most cases of melanoma. RSK (p90 ribosomal S6 kinase) is a MAPK-activated protein kinase required for melanoma growth and proliferation, but relatively little is known about its exact function and the nature of its substrates. Herein, we used a quantitative phosphoproteomics approach to define the signaling networks regulated by RSK in melanoma. To more accurately predict direct phosphorylation substrates, we defined the RSK consensus phosphorylation motif and found significant overlap with the binding consensus of 14-3-3 proteins. We thus characterized the phospho-dependent 14-3-3 interactome in melanoma cells and found that a large proportion of 14-3-3 binding proteins are also potential RSK substrates. Our results show that RSK phosphorylates the tumor suppressor PDCD4 (programmed cell death protein 4) on two serine residues (Ser76 and Ser457) that regulate its subcellular localization and interaction with 14-3-3 proteins. We found that 14-3-3 binding promotes PDCD4 degradation, suggesting an important role for RSK in the inactivation of PDCD4 in melanoma. In addition to this tumor suppressor, our results suggest the involvement of RSK in a vast array of unexplored biological functions with relevance in oncogenesis.
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α-Lipoic acid prevents p53 degradation in colon cancer cells by blocking NF-κB induction of RPS6KA4. Anticancer Drugs 2013; 24:555-65. [PMID: 23599020 DOI: 10.1097/cad.0b013e32836181eb] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
α-Lipoic acid (α-LA) is a biogenic antioxidant that has been used successfully in the treatment of diabetic polyneuropathy and its application to many oxidative stress-associated chronic diseases has increased. In this study, we investigated the effect of α-LA on colorectal cancer cell growth and its underlying mechanism. α-LA treatment resulted in a marked reduction in the growth of HCT116 colon cancer cells in a dose-dependent manner through the G1 arrest of the cell cycle and apoptosis induction. α-LA treatment significantly increased tumor cell response to various apoptotic stresses, such as etoposide, 5-fluorouracil, UVC, γ-irradiation, hypoxia, and tumor necrosis factor α (TNFα). Interestingly, α-LA increased p53 protein stability and its apoptosis-enhancing effect was more evident in wild-type p53-carrying cells compared with p53-deficient cells, suggesting that the proapoptotic role of α-LA is associated with its p53-stabilizing function. On the basis of our microarray data showing α-LA downregulation of the ribosomal protein p90S6K (RPS6KA4), which has been reported to inhibit p53 function, we tested whether α-LA regulation of RPS6KA4 is associated with its proapoptotic function. α-LA treatment led to a marked reduction in the RPS6KA4 mRNA level in multiple colorectal cancer cells and restoration of RPS6KA4 expression markedly attenuated α-LA induction of apoptosis in a p53-dependent manner. In addition, we observed that RPS6KA4 expression is activated by TNFα whereas both basal and TNFα induction of RPS6KA4 are inhibited by the nuclear factor-κB (NF-κB) inhibitor BAY11-7082 or transfection of a dominant-negative mutant of NF-κB, indicating that NF-κB plays a crucial role in RPS6KA4 gene expression. Finally, we found that α-LA exerts an inhibitory effect on the nuclear translocation of NF-κB triggered by TNFα. Collectively, our study shows that α-LA suppresses colorectal tumor cell growth at least partially by preventing RPS6KA4-mediated p53 inhibition through blockade of NF-κB signaling.
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RSK2 regulates endocytosis of FGF receptor 1 by phosphorylation on serine 789. Oncogene 2013; 33:4823-36. [DOI: 10.1038/onc.2013.425] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 08/29/2013] [Accepted: 09/09/2013] [Indexed: 12/13/2022]
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Kang JH, Toita R, Kim CW, Katayama Y. Protein kinase C (PKC) isozyme-specific substrates and their design. Biotechnol Adv 2012; 30:1662-72. [DOI: 10.1016/j.biotechadv.2012.07.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/17/2012] [Accepted: 07/18/2012] [Indexed: 11/30/2022]
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Saha M, Carriere A, Cheerathodi M, Zhang X, Lavoie G, Rush J, Roux PP, Ballif BA. RSK phosphorylates SOS1 creating 14-3-3-docking sites and negatively regulating MAPK activation. Biochem J 2012; 447:159-66. [PMID: 22827337 PMCID: PMC4198020 DOI: 10.1042/bj20120938] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The extent and duration of MAPK (mitogen-activated protein kinase) signalling govern a diversity of normal and aberrant cellular outcomes. Genetic and pharmacological disruption of the MAPK-activated kinase RSK (ribosomal S6 kinase) leads to elevated MAPK activity indicative of a RSK-dependent negative feedback loop. Using biochemical, pharmacological and quantitative MS approaches we show that RSK phosphorylates the Ras activator SOS1 (Son of Sevenless homologue 1) in cultured cells on two C-terminal residues, Ser(1134) and Ser(1161). Furthermore, we find that RSK-dependent SOS1 phosphorylation creates 14-3-3-binding sites. We show that mutating Ser(1134) and Ser(1161) disrupts 14-3-3 binding and modestly increases and extends MAPK activation. Together these data suggest that one mechanism whereby RSK negatively regulates MAPK activation is via site-specific SOS1 phosphorylation.
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Affiliation(s)
- Madhurima Saha
- Department of Biology, University of Vermont, Burlington, VT, 05405, U.S.A
| | - Audrey Carriere
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
| | | | - Xiaocui Zhang
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
| | - Geneviève Lavoie
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
| | - John Rush
- Cell Signaling Technology, Inc., 3 Trask Lane, Danvers, MA, 01923, U.S.A
| | - Philippe P. Roux
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
| | - Bryan A. Ballif
- Department of Biology, University of Vermont, Burlington, VT, 05405, U.S.A
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Regulatory effects of programmed cell death 4 (PDCD4) protein in interferon (IFN)-stimulated gene expression and generation of type I IFN responses. Mol Cell Biol 2012; 32:2809-22. [PMID: 22586265 DOI: 10.1128/mcb.00310-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The precise mechanisms by which the activation of interferon (IFN) receptors (IFNRs) ultimately controls mRNA translation of specific target genes to induce IFN-dependent biological responses remain ill defined. We provide evidence that IFN-α induces phosphorylation of programmed cell death 4 (PDCD4) protein on Ser67. This IFN-α-dependent phosphorylation is mediated by either the p70 S6 kinase (S6K) or the p90 ribosomal protein S6K (RSK) in a cell-type-specific manner. IFN-dependent phosphorylation of PDCD4 results in downregulation of PDCD4 protein levels as the phosphorylated form of PDCD4 interacts with the ubiquitin ligase β-TRCP (β-transducin repeat-containing protein) and undergoes degradation. This process facilitates IFN-induced eukaryotic translation initiation factor 4A (eIF4A) activity and binding to translation initiation factor eIF4G to promote mRNA translation. Our data establish that PDCD4 degradation ultimately facilitates expression of several ISG protein products that play important roles in the generation of IFN responses, including IFN-stimulated gene 15 (ISG15), p21(WAF1/CIP1), and Schlafen 5 (SLFN5). Moreover, engagement of the RSK/PDCD4 pathway by the type I IFNR is required for the suppressive effects of IFN-α on normal CD34(+) hematopoietic precursors and for antileukemic effects in vitro. Altogether, these findings provide evidence for a unique function of PDCD4 in the type I IFN system and indicate a key regulatory role for this protein in mRNA translation of ISGs and control of IFN responses.
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Progestins activate 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) in breast cancer cells. Biochem J 2012; 442:345-56. [PMID: 22115192 DOI: 10.1042/bj20111418] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PFKFB (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase) catalyses the synthesis and degradation of Fru-2,6-P2 (fructose-2,6-bisphosphate), a key modulator of glycolysis and gluconeogenesis. The PFKFB3 gene is extensively involved in cell proliferation owing to its key role in carbohydrate metabolism. In the present study we analyse its mechanism of regulation by progestins in breast cancer cells. We report that exposure of T47D cells to synthetic progestins (ORG2058 or norgestrel) leads to a rapid increase in Fru-2,6-P2 concentration. Our Western blot results are compatible with a short-term activation due to PFKFB3 isoenzyme phosphorylation and a long-term sustained action due to increased PFKFB3 protein levels. Transient transfection of T47D cells with deleted gene promoter constructs allowed us to identify a PRE (progesterone-response element) to which PR (progesterone receptor) binds and thus transactivates PFKFB3 gene transcription. PR expression in the PR-negative cell line MDA-MB-231 induces endogenous PFKFB3 expression in response to norgestrel. Direct binding of PR to the PRE box (-3490 nt) was confirmed by ChIP (chromatin immunoprecipiation) experiments. A dual mechanism affecting PFKFB3 protein and gene regulation operates in order to assure glycolysis in breast cancer cells. An immediate early response through the ERK (extracellular-signal-regulated kinase)/RSK (ribosomal S6 kinase) pathway leading to phosphorylation of PFKFB3 on Ser461 is followed by activation of mRNA transcription via cis-acting sequences on the PFKFB3 promoter.
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Abstract
The RSK (90 kDa ribosomal S6 kinase) family comprises a group of highly related serine/threonine kinases that regulate diverse cellular processes, including cell growth, proliferation, survival and motility. This family includes four vertebrate isoforms (RSK1, RSK2, RSK3 and RSK4), and single family member orthologues are also present in Drosophila and Caenorhabditis elegans. The RSK isoforms are downstream effectors of the Ras/ERK (extracellular-signal-regulated kinase) signalling pathway. Significant advances in the field of RSK signalling have occurred in the past few years, including several new functions ascribed to the RSK isoforms, the discovery of novel protein substrates and the implication of different RSK isoforms in cancer. Collectively, these new findings increase the diversity of biological functions regulated by RSK, and highlight potential new directions of research. In the present paper, we review the structure, expression and activation mechanisms of the RSK isoforms, and discuss their physiological roles on the basis of established substrates and recent discoveries.
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Ben-Shimon A, Niv MY. Deciphering the Arginine-binding preferences at the substrate-binding groove of Ser/Thr kinases by computational surface mapping. PLoS Comput Biol 2011; 7:e1002288. [PMID: 22125489 PMCID: PMC3219626 DOI: 10.1371/journal.pcbi.1002288] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Accepted: 10/12/2011] [Indexed: 11/18/2022] Open
Abstract
Protein kinases are key signaling enzymes that catalyze the transfer of γ-phosphate from an ATP molecule to a phospho-accepting residue in the substrate. Unraveling the molecular features that govern the preference of kinases for particular residues flanking the phosphoacceptor is important for understanding kinase specificities toward their substrates and for designing substrate-like peptidic inhibitors. We applied ANCHORSmap, a new fragment-based computational approach for mapping amino acid side chains on protein surfaces, to predict and characterize the preference of kinases toward Arginine binding. We focus on positions P−2 and P−5, commonly occupied by Arginine (Arg) in substrates of basophilic Ser/Thr kinases. The method accurately identified all the P−2/P−5 Arg binding sites previously determined by X-ray crystallography and produced Arg preferences that corresponded to those experimentally found by peptide arrays. The predicted Arg-binding positions and their associated pockets were analyzed in terms of shape, physicochemical properties, amino acid composition, and in-silico mutagenesis, providing structural rationalization for previously unexplained trends in kinase preferences toward Arg moieties. This methodology sheds light on several kinases that were described in the literature as having non-trivial preferences for Arg, and provides some surprising departures from the prevailing views regarding residues that determine kinase specificity toward Arg. In particular, we found that the preference for a P−5 Arg is not necessarily governed by the 170/230 acidic pair, as was previously assumed, but by several different pairs of acidic residues, selected from positions 133, 169, and 230 (PKA numbering). The acidic residue at position 230 serves as a pivotal element in recognizing Arg from both the P−2 and P−5 positions. Protein kinases are key signaling enzymes and major drug targets that catalyze the transfer of phosphate group to a phospho-accepting residue in the substrate. Unraveling molecular features that govern the preference of kinases for particular residues flanking the phosphoacceptor (substrate consensus sequence, SCS) is important for understanding kinase-substrates specificities and for designing peptidic inhibitors. Current methods used to predict this set of essential residues usually rely on linking between experimentally determined SCSs to kinase sequences. As such, these methods are less sensitive when specificity is dictated by subtle or kinase-unique sequence/structural features. In this study, we took a different approach for studying kinases specificities, by applying a new fragment-based method for mapping amino acid side chains on protein surfaces. We predicted and characterized the preference of Ser/Thr kinases toward Arginine binding, using the unbound kinase structures. The method produced high quality predictions and was able to provide novel insights and interesting departures from the prevailing views regarding the specificity-determining elements governing specificity toward Arginine. This work paves the way for studying the kinase binding preferences for other amino acids, for predicting protein-peptide structures, for facilitating the design of novel inhibitors, and for re-engineering of kinase specificities.
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Affiliation(s)
- Avraham Ben-Shimon
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment and The Fritz Haber Center for Molecular Dynamics, The Hebrew University, Israel
| | - Masha Y. Niv
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment and The Fritz Haber Center for Molecular Dynamics, The Hebrew University, Israel
- * E-mail:
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Andreani A, Granaiola M, Leoni A, Locatelli A, Morigi R, Rambaldi M, Varoli L, Lannigan D, Smith J, Scudiero D, Kondapaka S, Shoemaker RH. Imidazo[2,1-b]thiazole guanylhydrazones as RSK2 inhibitors. Eur J Med Chem 2011; 46:4311-23. [DOI: 10.1016/j.ejmech.2011.07.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/24/2011] [Accepted: 07/01/2011] [Indexed: 10/18/2022]
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Activation and function of the MAPKs and their substrates, the MAPK-activated protein kinases. Microbiol Mol Biol Rev 2011; 75:50-83. [PMID: 21372320 DOI: 10.1128/mmbr.00031-10] [Citation(s) in RCA: 2174] [Impact Index Per Article: 167.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The mitogen-activated protein kinases (MAPKs) regulate diverse cellular programs by relaying extracellular signals to intracellular responses. In mammals, there are more than a dozen MAPK enzymes that coordinately regulate cell proliferation, differentiation, motility, and survival. The best known are the conventional MAPKs, which include the extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun amino-terminal kinases 1 to 3 (JNK1 to -3), p38 (α, β, γ, and δ), and ERK5 families. There are additional, atypical MAPK enzymes, including ERK3/4, ERK7/8, and Nemo-like kinase (NLK), which have distinct regulation and functions. Together, the MAPKs regulate a large number of substrates, including members of a family of protein Ser/Thr kinases termed MAPK-activated protein kinases (MAPKAPKs). The MAPKAPKs are related enzymes that respond to extracellular stimulation through direct MAPK-dependent activation loop phosphorylation and kinase activation. There are five MAPKAPK subfamilies: the p90 ribosomal S6 kinase (RSK), the mitogen- and stress-activated kinase (MSK), the MAPK-interacting kinase (MNK), the MAPK-activated protein kinase 2/3 (MK2/3), and MK5 (also known as p38-regulated/activated protein kinase [PRAK]). These enzymes have diverse biological functions, including regulation of nucleosome and gene expression, mRNA stability and translation, and cell proliferation and survival. Here we review the mechanisms of MAPKAPK activation by the different MAPKs and discuss their physiological roles based on established substrates and recent discoveries.
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Kaoud TS, Devkota AK, Harris R, Rana MS, Abramczyk O, Warthaka M, Lee S, Girvin ME, Riggs AF, Dalby KN. Activated ERK2 is a monomer in vitro with or without divalent cations and when complexed to the cytoplasmic scaffold PEA-15. Biochemistry 2011; 50:4568-78. [PMID: 21506533 DOI: 10.1021/bi200202y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The extracellular signal-regulated protein kinase, ERK2, fully activated by phosphorylation and without a His(6) tag, shows little tendency to dimerize with or without either calcium or magnesium ions when analyzed by light scattering or analytical ultracentrifugation. Light scattering shows that ~90% of ERK2 is monomeric. Sedimentation equilibrium data (obtained at 4.8-11.2 μM ERK2) with or without magnesium (10 mM) are well described by an ideal one-component model with a fitted molar mass of 40180 ± 240 Da (without Mg(2+) ions) or 41290 ± 330 Da (with Mg(2+) ions). These values, close to the sequence-derived mass of 41711 Da, indicate that no significant dimerization of ERK2 occurs in solution. Analysis of sedimentation velocity data for a 15 μM solution of ERK2 with an enhanced van Holde-Weischet method determined the sedimentation coefficient (s) to be ~3.22 S for activated ERK2 with or without 10 mM MgCl(2). The frictional coefficient ratio (f/f(0)) of 1.28 calculated from the sedimentation velocity and equilibrium data is close to that expected for an ~42 kDa globular protein. The translational diffusion coefficient of ~8.3 × 10(-7) cm(2) s(-1) calculated from the experimentally determined molar mass and sedimentation coefficient agrees with the value determined by dynamic light scattering in the absence and presence of calcium or magnesium ions and a value determined by NMR spectrometry. ERK2 has been proposed to homodimerize and bind only to cytoplasmic but not nuclear proteins [Casar, B., et al. (2008) Mol. Cell 31, 708-721]. Our light scattering data show, however, that ERK2 forms a strong 1:1 complex of ~57 kDa with the cytoplasmic scaffold protein PEA-15. Thus, ERK2 binds PEA-15 as a monomer. Our data provide strong evidence that ERK2 is monomeric under physiological conditions. Analysis of the same ERK2 construct with the nonphysiological His(6) tag shows substantial dimerization under the same ionic conditions.
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Affiliation(s)
- Tamer S Kaoud
- Division of Medicinal Chemistry, University of Texas, Austin, TX 78712, USA.
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31
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Abstract
p90 ribosomal S6 kinase 2 (p90RSK2) is important in diverse cellular processes including gene expression, cell proliferation, and survival. We found that p90RSK2 is commonly activated in diverse leukemia cell lines expressing different leukemogenic tyrosine kinases, including BCR-ABL and FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD). Interestingly, in a murine BM transplantation (BMT) model, genetic deficiency of RSK2 did not affect the pathogenesis or disease progression of BCR-ABL-induced myeloproliferative neoplasm (PN). In contrast, FLT3-ITD induced a T-cell acute lymphoblastic leukemia in BMT mice receiving RSK2 knockout (KO) BM cells, phenotypically distinct from the myeloproliferative neoplasm induced by FLT3-ITD using wild-type BM cells. In consonance with these results, inhibition of RSK2 by an RSK inhibitor, fmk, did not effectively induce apoptosis in BCR-ABL-expressing murine Ba/F3 cells, human K562 cells or primary tissue samples from CML patients, whereas fmk treatment induced significant apoptotic cell death not only in FLT3-ITD-positive Ba/F3 cells, human Molm14 and Mv(4;11) leukemia cells, but also in primary tissue samples from AML patients. These results suggest that RSK2 is dispensable for BCR-ABL-induced myeloid leukemia, but may be required for pathogenesis and lineage determination in FLT3-ITD-induced hematopoietic transformation. RSK2 may thus represent an alternative therapeutic target in the treatment of FLT3-ITD-positive leukemia.
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32
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Cargnello M, Roux PP. Activation and Function of the MAPKs and Their Substrates, the MAPK-Activated Protein Kinases. Microbiol Mol Biol Rev 2011. [DOI: 78495111110.1128/mmbr.00031-10' target='_blank'>'"<>78495111110.1128/mmbr.00031-10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [78495111110.1128/mmbr.00031-10','', '10.1016/0014-5793(95)01170-j')">Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
78495111110.1128/mmbr.00031-10" />
Abstract
SUMMARYThe mitogen-activated protein kinases (MAPKs) regulate diverse cellular programs by relaying extracellular signals to intracellular responses. In mammals, there are more than a dozen MAPK enzymes that coordinately regulate cell proliferation, differentiation, motility, and survival. The best known are the conventional MAPKs, which include the extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun amino-terminal kinases 1 to 3 (JNK1 to -3), p38 (α, β, γ, and δ), and ERK5 families. There are additional, atypical MAPK enzymes, including ERK3/4, ERK7/8, and Nemo-like kinase (NLK), which have distinct regulation and functions. Together, the MAPKs regulate a large number of substrates, including members of a family of protein Ser/Thr kinases termed MAPK-activated protein kinases (MAPKAPKs). The MAPKAPKs are related enzymes that respond to extracellular stimulation through direct MAPK-dependent activation loop phosphorylation and kinase activation. There are five MAPKAPK subfamilies: the p90 ribosomal S6 kinase (RSK), the mitogen- and stress-activated kinase (MSK), the MAPK-interacting kinase (MNK), the MAPK-activated protein kinase 2/3 (MK2/3), and MK5 (also known as p38-regulated/activated protein kinase [PRAK]). These enzymes have diverse biological functions, including regulation of nucleosome and gene expression, mRNA stability and translation, and cell proliferation and survival. Here we review the mechanisms of MAPKAPK activation by the different MAPKs and discuss their physiological roles based on established substrates and recent discoveries.
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Affiliation(s)
- Marie Cargnello
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada
- Molecular Biology Program, Université de Montréal, Montreal, Quebec, Canada
| | - Philippe P. Roux
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada
- Molecular Biology Program, Université de Montréal, Montreal, Quebec, Canada
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
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Cuello F, Bardswell SC, Haworth RS, Ehler E, Sadayappan S, Kentish JC, Avkiran M. Novel role for p90 ribosomal S6 kinase in the regulation of cardiac myofilament phosphorylation. J Biol Chem 2010; 286:5300-10. [PMID: 21148481 DOI: 10.1074/jbc.m110.202713] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In myocardium, the 90-kDa ribosomal S6 kinase (RSK) is activated by diverse stimuli and regulates the sarcolemmal Na(+)/H(+) exchanger through direct phosphorylation. Only limited information is available on other cardiac RSK substrates and functions. We evaluated cardiac myosin-binding protein C (cMyBP-C), a sarcomeric regulatory phosphoprotein, as a potential RSK substrate. In rat ventricular myocytes, RSK activation by endothelin 1 (ET1) increased cMyBP-C phosphorylation at Ser(282), which was inhibited by the selective RSK inhibitor D1870. Neither ET1 nor D1870 affected the phosphorylation status of Ser(273) or Ser(302), cMyBP-C residues additionally targeted by cAMP-dependent protein kinase (PKA). Complementary genetic gain- and loss-of-function experiments, through the adenoviral expression of wild-type or kinase-inactive RSK isoforms, confirmed RSK-mediated phosphorylation of cMyBP-C at Ser(282). Kinase assays utilizing as substrate wild-type or mutated (S273A, S282A, S302A) recombinant cMyBP-C fragments revealed direct and selective Ser(282) phosphorylation by RSK. Immunolabeling with a Ser(P)(282) antibody and confocal fluorescence microscopy showed RSK-mediated phosphorylation of cMyBP-C across the C-zones of sarcomeric A-bands. In chemically permeabilized mouse ventricular muscles, active RSK again induced selective Ser(282) phosphorylation in cMyBP-C, accompanied by significant reduction in Ca(2+) sensitivity of force development and significant acceleration of cross-bridge cycle kinetics, independently of troponin I phosphorylation at Ser(22)/Ser(23). The magnitudes of these RSK-induced changes were comparable with those induced by PKA, which phosphorylated cMyBP-C additionally at Ser(273) and Ser(302). We conclude that Ser(282) in cMyBP-C is a novel cardiac RSK substrate and its selective phosphorylation appears to regulate cardiac myofilament function.
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Affiliation(s)
- Friederike Cuello
- King's College London British Heart Foundation Centre, Cardiovascular Division, St Thomas' Hospital, London SE1 7EH, United Kingdom
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Direct roles of the signaling kinase RSK2 in Cdc25C activation during Xenopus oocyte maturation. Proc Natl Acad Sci U S A 2010; 107:19885-90. [PMID: 21041626 DOI: 10.1073/pnas.1003528107] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The induction of M phase in eukaryotic cell cycles requires robust activation of Cdc2/cyclin B by Cdc25, which itself is robustly activated by serine/threonine phosphorylations. Although multiple protein kinases that directly activate Cdc25C have been identified, whether the combination of different primary phosphorylations of Cdc25C is sufficient to fully activate Cdc25C has not been determined. By analyzing the GST-Cdc25C phosphorylating activity in Xenopus egg extracts, we previously defined roles of MAPK and Cdc2/cyclin B in partially activating Cdc25C and predicted the presence of another major Cdc25C-activating kinase. In this study, we demonstrate that this missing kinase is RSK2, which phosphorylates three sites in Cdc25C and also partially activates Cdc25C. However, the phosphorylations catalyzed by MAPK, Cdc2, and RSK2 fail to fully activate Cdc25C, suggesting that additional biochemical events are required to fully activate this key cell cycle regulator.
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35
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Abstract
IMPORTANCE OF THE FIELD p90 ribosomal S6 kinase 2 (RSK2) belongs to a Ser/Thr kinase family containing four members, RSK1 - 4, which play an essential role in a number of cellular functions including cell cycle, survival and proliferation. Recent advances reveal a crucial role of RSK2 in oncogenesis and tumor progression, making RSK2 an attractive therapeutic target for cancer treatment. AREA COVERED IN THIS REVIEW Recent findings identifying the role of RSK2 in human cancers, including hematopoietic malignancies and solid tumors. Therapeutic implications of targeting RSK2 are also discussed with regard to clinical circumstance. WHAT THE READER WILL GAIN A better understanding of molecular mechanisms underlying RSK2 activation and its contribution to human cancers and also insight into the development of novel targeted cancer therapy. TAKE HOME MESSAGE The significance of RSK2 in cancer cell survival, proliferation, invasion and tumor metastasis varies amongst human malignancies and depends on the signaling properties of the oncogenes and cellular microenvironment of the transformed cells. Thus, further exploitation of RSK2 signaling and its dynamic interaction with other crucial oncogenic and pro-metastatic pathways in different human malignancies is needed for more effective therapeutic interventions.
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Affiliation(s)
- Sumin Kang
- Emory University School of Medicine, Winship Cancer Institute of Emory, Department of Hematology and Medical Oncology, Atlanta, GA 30322, USA. ;
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36
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Frijns E, Sachs N, Kreft M, Wilhelmsen K, Sonnenberg A. EGF-induced MAPK signaling inhibits hemidesmosome formation through phosphorylation of the integrin {beta}4. J Biol Chem 2010; 285:37650-62. [PMID: 20870721 DOI: 10.1074/jbc.m110.138818] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Migration of keratinocytes requires a regulated and dynamic turnover of hemidesmosomes (HDs). We and others have previously identified three serine residues on the integrin β4 cytoplasmic domain that play a critical role in the regulation of HD disassembly. In this study we show that only two of these residues (Ser-1356 and Ser-1364) are phosphorylated in keratinocytes after stimulation with either PMA or EGF. Furthermore, in direct contrast to previous studies performed in vitro, we found that the PMA- and EGF-stimulated phosphorylation of β4 is not mediated by PKC, but by ERK1/2 and its downstream effector kinase p90RSK1/2. EGF-stimulated phosphorylation of β4 increased keratinocyte migration, and reduced the number of stable HDs. Furthermore, mutation of the two serines in β4 to phospho-mimicking aspartic acid decreased its interaction with the cytoskeletal linker protein plectin, as well as the strength of α6β4-mediated adhesion to laminin-332. During mitotic cell rounding, when the overall cell-substrate area is decreased and the number of HDs is reduced, β4 was only phosphorylated on Ser-1356 by a distinct, yet unidentified, kinase. Collectively, these data demonstrate an important role of β4 phosphorylation on residues Ser-1356 and Ser-1364 in the formation and/or stability of HDs.
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Affiliation(s)
- Evelyne Frijns
- Division of Cell Biology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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Wang A, Rud J, Olson CM, Anguita J, Osborne BA. Phosphorylation of Nur77 by the MEK-ERK-RSK Cascade Induces Mitochondrial Translocation and Apoptosis in T Cells. THE JOURNAL OF IMMUNOLOGY 2009; 183:3268-77. [DOI: 10.4049/jimmunol.0900894] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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38
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Strachan RT, Sheffler DJ, Willard B, Kinter M, Kiselar JG, Roth BL. Ribosomal S6 kinase 2 directly phosphorylates the 5-hydroxytryptamine 2A (5-HT2A) serotonin receptor, thereby modulating 5-HT2A signaling. J Biol Chem 2008; 284:5557-73. [PMID: 19103592 DOI: 10.1074/jbc.m805705200] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 5-hydroxytryptamine 2A (5-HT(2A)) receptor is a member of the G protein-coupled receptor superfamily (GPCR) and plays a key role in transducing a variety of cellular signals elicited by 5-hydroxytryptamine in both peripheral and central tissues. Despite its broad physiological importance, our current understanding of 5-HT(2A) receptor regulation is incomplete. We recently reported the novel finding that the multifunctional ERK effector ribosomal S6 kinase 2 (RSK2) physically interacts with the 5-HT(2A) receptor third intracellular (i3) loop and modulates receptor signaling (Sheffler, D. J., Kroeze, W. K., Garcia, B. G., Deutch, A. Y., Hufeisen, S. J., Leahy, P., Bruning, J. C., and Roth, B. L. (2006) Proc. Natl. Acad. Sci. U. S. A. 103, 4717-4722). We report here that RSK2 directly phosphorylates the 5-HT(2A) receptor i3 loop at the conserved residue Ser-314, thereby modulating 5-HT(2A) receptor signaling. Furthermore, these studies led to the discovery that RSK2 is required for epidermal growth factor-mediated heterologous desensitization of the 5-HT(2A) receptor. We arrived at these conclusions via multiple lines of evidence, including in vitro kinase experiments, tandem mass spectrometry, and site-directed mutagenesis. Our findings were further validated using phospho-specific Western blot analysis, metabolic labeling studies, and whole-cell signaling experiments. These results support a novel regulatory mechanism in which a downstream effector of the ERK/MAPK pathway directly interacts with, phosphorylates, and modulates signaling of the 5-HT(2A) serotonin receptor. To our knowledge, these findings are the first to demonstrate that a downstream member of the ERK/MAPK cascade phosphorylates a GPCR as well as mediates cross-talk between a growth factor and a GPCR.
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Affiliation(s)
- Ryan T Strachan
- Department of Biochemistry, Case Western Reserve University Medical School, Cleveland, Ohio 44106, USA
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Anjum R, Blenis J. The RSK family of kinases: emerging roles in cellular signalling. Nat Rev Mol Cell Biol 2008; 9:747-58. [PMID: 18813292 DOI: 10.1038/nrm2509] [Citation(s) in RCA: 570] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The 90 kDa ribosomal S6 kinase (RSK) family of proteins is a group of highly conserved Ser/Thr kinases that regulate diverse cellular processes, such as cell growth, cell motility, cell survival and cell proliferation. RSKs are downstream effectors of the Ras-extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signalling cascade. Significant advances in the field of RSK and ERK/MAPK signalling have occurred in the past few years, including biological insights and the discovery of novel substrates and new RSK regulatory mechanisms. Collectively, these data expand the current models of RSK signalling and highlight potential directions of research in RSK-mediated survival, growth, proliferation and migration.
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Affiliation(s)
- Rana Anjum
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA
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Sopko R, Andrews BJ. Linking the kinome and phosphorylome--a comprehensive review of approaches to find kinase targets. MOLECULAR BIOSYSTEMS 2008; 4:920-33. [PMID: 18704230 DOI: 10.1039/b801724g] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Protein phosphorylation is associated with most cell signaling and developmental processes in eukaryotes. Despite the vast extent of the phosphoproteome within the cell, connecting specific kinases with relevant targets remains a significant experimental frontier. The challenge of linking kinases and their substrates reflects the complexity of kinase function. For example, kinases tend to exert their biological effects through supernumerary, redundant phosphorylation, often on multiple protein complex components. Although these types of phosphorylation events are biologically significant, those kinases responsible are often difficult to identify. Recent methods for global analysis of protein phosphorylation promise to substantially accelerate efforts to map the dynamic phosphorylome. Here, we review both conventional methods to identify kinase targets and more comprehensive genomic and proteomic approaches to connect the kinome and phosphorylome.
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Affiliation(s)
- Richelle Sopko
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada
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Lu Z, Abe JI, Taunton J, Lu Y, Shishido T, McClain C, Yan C, Xu SP, Spangenberg TM, Xu H. Reactive oxygen species-induced activation of p90 ribosomal S6 kinase prolongs cardiac repolarization through inhibiting outward K+ channel activity. Circ Res 2008; 103:269-78. [PMID: 18599872 DOI: 10.1161/circresaha.107.166678] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
p90 ribosomal S6 kinase (p90RSK) is activated in cardiomyopathies caused by conditions such as ischemia/reperfusion injury and diabetes mellitus in which prolongation of cardiac repolarization and frequent arrhythmias are common. Molecular mechanisms underlying the electric remodeling in cardiac diseases are largely unknown. In the present study, we determined the role of p90RSK activation in the modulation of voltage-gated K+ channel activity determining cardiac repolarization. Mice with increased cardiac p90RSK activity due to transgenic expression of p90RSK (p90RSK-Tg) had prolongation of QT intervals and of ventricular myocyte action potential durations. Fast transient outward K+ current (I(to,f)), slow delayed outward K+ current (I(K,slow)), and steady-state K+ current (I(SS)) were significantly decreased in p90RSK-Tg mouse ventricular myocytes. mRNA levels of Kv4.3, Kv4.2, Kv1.5, Kv2.1, and KChIP2 from ventricles between p90RSK-Tg and nontransgenic littermate control mice were similar, as assessed by quantitative reverse transcriptase-polymerase chain reaction, indicating that p90RSK regulates voltage-gated K+ channels through posttranslational modification. Kv4.3- and Kv1.5- rather than Kv4.2- and Kv2.1-encoded channels in HEK 293 cells were inhibited by p90RSK. In vitro phosphorylation analysis showed that Kv4.3 was phosphorylated by p90RSK at 2 conserved sites, Ser516 and Ser550. p90RSK expression significantly inhibited Kv4.3- and Kv4.3 and KChIP2-encoded channel activities in HEK 293 cells, whereas p90RSK's effects were blocked by amino acid mutation(s) at phosphorylation site(s) in Kv4.3. Hydrogen peroxide, a mediator of induced cardiac p90RSK activation in ischemia/reperfusion injury and diabetes mellitus, had effects similar to those of p90RSK on Kv4.3- or Kv4.3- and KChIP2-encoded channels. Fluoromethylketone, a specific p90RSK inhibitor, abolished hydrogen peroxide effects. These findings indicate that p90RSK activation is critical for reactive oxygen species-mediated inhibition of voltage-gated K+ channel activity and leads to prolongation of cardiac repolarization.
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Affiliation(s)
- Zhibo Lu
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
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42
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The Coffin-Lowry syndrome-associated protein RSK2 is implicated in calcium-regulated exocytosis through the regulation of PLD1. Proc Natl Acad Sci U S A 2008; 105:8434-9. [PMID: 18550821 DOI: 10.1073/pnas.0710676105] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exocytosis of neurotransmitters and hormones occurs through the fusion of secretory vesicles with the plasma membrane. This highly regulated process involves key proteins, such as SNAREs, and specific lipids at the site of membrane fusion. Phospholipase D (PLD) has recently emerged as a promoter of membrane fusion in various exocytotic events potentially by providing fusogenic cone-shaped phosphatidic acid. We show here that PLD1 is regulated by ribosomal S6 kinase 2 (RSK2)-dependent phosphorylation. RSK2 is activated by a high K(+)-induced rise in cytosolic calcium. Expression of inactive RSK2 mutants or selective knockdown of endogenous RSK2 dramatically affects the different kinetic components of the exocytotic response in chromaffin cells. RSK2 physically interacts with and stimulates PLD activity through the phosphorylation of Thr-147 in the PLD1 amino-terminal phox homology domain. Expression of PLD1 phosphomimetic mutants fully restores secretion in cells depleted of RSK2, suggesting that RSK2 is a critical upstream signaling element in the activation of PLD1 to produce the lipids required for exocytosis. We propose that PLD-related defects in neuronal and endocrine activities could contribute to the effect observed after the loss-of-function mutations in Rsk2 that lead to Coffin-Lowry syndrome, an X-linked form of growth and mental retardation.
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43
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Ikuta M, Kornienko M, Byrne N, Reid JC, Mizuarai S, Kotani H, Munshi SK. Crystal structures of the N-terminal kinase domain of human RSK1 bound to three different ligands: Implications for the design of RSK1 specific inhibitors. Protein Sci 2007; 16:2626-35. [PMID: 17965187 DOI: 10.1110/ps.073123707] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The p90 ribosomal S6 kinases (RSKs) also known as MAPKAP-Ks are serine/threonine protein kinases that are activated by ERK or PDK1 and act as downstream effectors of mitogen-activated protein kinase (MAPK). RSK1, a member of the RSK family, contains two distinct kinase domains in a single polypeptide chain, the regulatory C-terminal kinase domain (CTKD) and the catalytic N-terminal kinase domain (NTKD). Autophosphorylation of the CTKD leads to activation of the NTKD that subsequently phosphorylates downstream substrates. Here we report the crystal structures of the unactivated RSK1 NTKD bound to different ligands at 2.0 A resolution. The activation loop and helix alphaC, key regulatory elements of kinase function, are disordered. The DFG motif of the inactive RSK1 adopts an "active-like" conformation. The beta-PO(4) group in the AMP-PCP complex adopts a unique conformation that may contribute to inactivity of the enzyme. Structures of RSK1 ligand complexes offer insights into the design of novel anticancer agents and into the regulation of the catalytic activity of RSKs.
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Affiliation(s)
- Mari Ikuta
- Department of Structural Biology, Merck Research Laboratories, West Point, Pennsylvania 19486, USA. mari_ikuta@.merck.com
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44
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Baljuls A, Mueller T, Drexler HCA, Hekman M, Rapp UR. Unique N-region Determines Low Basal Activity and Limited Inducibility of A-RAF Kinase. J Biol Chem 2007; 282:26575-90. [PMID: 17613527 DOI: 10.1074/jbc.m702429200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In mammals the RAF family of serine/threonine kinases consists of three members, A-, B-, and C-RAF. A prominent feature of RAF isoforms regards differences in basal and inducible kinase activities. To elucidate the nature of these differences, we studied the role of the nonconserved residues within the N-region (Negative-charge regulatory region). The nonconserved amino acids in positions -3 and +1 relative to the highly conserved serine 299 in A-RAF and serine 338 in C-RAF have so far not been considered as regulatory residues. Here we demonstrate the essential role of these residues in the RAF activation process. Substitution of tyrosine 296 in A-RAF to arginine led to a constitutively active kinase. In contrast, substitution of glycine 300 by serine (mimicking B- and C-RAF) acts in an inhibitory manner. Consistent with these data, the introduction of glycine in the analogous position of C-RAF (S339G mutant) led to a constitutively active C-RAF kinase. Based on the three-dimensional structure of the catalytic domain of B-RAF and using the sequences of the N-regions of A- and C-RAF, we searched by molecular modeling for the putative contact points between these two moieties. A tight interaction between the N-region residue serine 339 of C-RAF and arginine 398 of the catalytic domain was identified and proposed to inhibit the kinase activity of RAF proteins, because abrogation of this interaction contributes to RAF activation. Furthermore, tyrosine 296 in A-RAF favors a spatial orientation of the N-region segment, which enables a tighter contact to the catalytic domain, whereas a glutamine residue at this position in C-RAF abrogates this interaction. Considering this observation, we suggest that tyrosine 296, which is unique for A-RAF, is a major determinant of the low activating potency of this RAF isoform.
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Affiliation(s)
- Angela Baljuls
- Institute for Medical Radiation and Cell Research, University of Wuerzburg, 97078 Wuerzburg, Germany
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45
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Kaphzan H, Doron G, Rosenblum K. Co-application of NMDA and dopamine-induced rapid translation of RSK2 in the mature hippocampus. J Neurochem 2007; 103:388-99. [PMID: 17645456 DOI: 10.1111/j.1471-4159.2007.04774.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Ribosomal S6 kinase2 (RSK2) is known to take part in several signal transduction cascades including Mitogen Activated Protein Kinase/Extracellular Regulated Kinase (MAPK/ERK). Following our recent observation that ERK can serve as a coincidence detector for fast and slow neurotransmission in the hippocampus, we analyzed the status of RSK2 phosphorylation subsequent to application of NMDA, dopamine, or both to preparations of mature hippocampal slices in Sprague-Dawley rats. RSK2 was indeed phosphorylated; however, in addition, the amount of RSK2 protein (60%) was induced within 10 min following stimulation. Moreover, the induced expression of RSK2 could be detected in both the cell body layer and the dendrites of hippocampal CA1 cells. Pharmacological analysis showed that RSK2 induction was MAPK ERK Kinase (MEK)-ERK independent, but mammalian Target of Rapamycin (mTOR) and translation dependent. We suggest that the fast kinetics of RSK2 translation that follows physiological stimulations, together with recent observations that its over-expression is vital for the attenuation of major signal transduction cascades, indicate an expanded physiological function of RSK2 in neurons, and sheds new light on the role of RSK2 in the Coffin-Lowry syndrome.
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Affiliation(s)
- Hanoch Kaphzan
- Department of Neurobiology and Ethology, Faculty of Science, Haifa University, Haifa, Israel
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46
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Konishi H, Namikawa K, Shikata K, Kobatake Y, Tachibana T, Kiyama H. Identification of peripherin as a Akt substrate in neurons. J Biol Chem 2007; 282:23491-9. [PMID: 17569669 DOI: 10.1074/jbc.m611703200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of Akt-mediated signaling pathways is crucial for survival and regeneration of injured neurons. In this study, we attempted to identify novel Akt substrates by using an antibody that recognized a consensus motif phosphorylated by Akt. PC12 cells that overexpressed constitutively active Akt were used. Using two-dimensional PAGE, we identified protein spots that exhibited increased immunostaining of the antibody. Mass spectrometry revealed several major spots as the neuronal intermediate filament protein, peripherin. Using several peripherin fragments, the phosphorylation site was determined as Ser(66) in its head domain in vitro. Furthermore, a co-immunoprecipitation experiment revealed that Akt interacted with the head domain of peripherin in HEK 293T cells. An antibody against phosphorylated peripherin was raised, and induction of phosphorylated peripherin was observed not only in Akt-activated cultured cells but also in nerve-injured hypoglossal motor neurons. These results suggest that peripherin is a novel substrate for Akt in vivo and that its phosphorylation may play a role in motor nerve regeneration.
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Affiliation(s)
- Hiroyuki Konishi
- Department of Anatomy and Neurobiology, Osaka City University, Graduate School of Medicine, Osaka 545-8585, Japan
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47
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Roux PP, Shahbazian D, Vu H, Holz MK, Cohen MS, Taunton J, Sonenberg N, Blenis J. RAS/ERK signaling promotes site-specific ribosomal protein S6 phosphorylation via RSK and stimulates cap-dependent translation. J Biol Chem 2007; 282:14056-64. [PMID: 17360704 PMCID: PMC3618456 DOI: 10.1074/jbc.m700906200] [Citation(s) in RCA: 572] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Converging signals from the mammalian target of rapamycin (mTOR) and phosphoinositide 3-kinase (PI3K) pathways are well established to modulate translation initiation. Less is known regarding the molecular basis of protein synthesis regulated by other inputs, such as agonists of the Ras/extracellular signal-regulated kinase (ERK) signaling cascade. Ribosomal protein (rp) S6 is a component of the 40S ribosomal subunit that becomes phosphorylated at several serine residues upon mitogen stimulation, but the exact molecular mechanisms regulating its phosphorylation and the function of phosphorylated rpS6 is poorly understood. Here, we provide evidence that activation of the p90 ribosomal S6 kinases (RSKs) by serum, growth factors, tumor promoting phorbol esters, and oncogenic Ras is required for rpS6 phosphorylation downstream of the Ras/ERK signaling cascade. We demonstrate that while ribosomal S6 kinase 1 (S6K1) phosphorylates rpS6 at all sites, RSK exclusively phosphorylates rpS6 at Ser(235/236) in vitro and in vivo using an mTOR-independent mechanism. Mutation of rpS6 at Ser(235/236) reveals that phosphorylation of these sites promotes its recruitment to the 7-methylguanosine cap complex, suggesting that Ras/ERK signaling regulates assembly of the translation preinitiation complex. These data demonstrate that RSK provides an mTOR-independent pathway linking the Ras/ERK signaling cascade to the translational machinery.
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Affiliation(s)
- Philippe P Roux
- Department of Pathology and Cell Biology, Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada.
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48
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Cohen MS, Hadjivassiliou H, Taunton J. A clickable inhibitor reveals context-dependent autoactivation of p90 RSK. Nat Chem Biol 2007; 3:156-60. [PMID: 17259979 PMCID: PMC3634365 DOI: 10.1038/nchembio859] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Accepted: 01/02/2007] [Indexed: 11/08/2022]
Abstract
p90 ribosomal protein S6 kinases (RSKs) integrate upstream signals through two catalytic domains. Autophosphorylation of Ser386 by the regulatory C-terminal kinase domain (CTD) is thought to be essential for activation of the N-terminal kinase domain (NTD), which phosphorylates multiple downstream targets. We recently reported fmk, an irreversible inhibitor of the CTD of RSK1 and RSK2. Here we describe fmk-pa, a propargylamine variant that has improved cellular potency and a 'clickable' tag for assessing the extent and selectivity of covalent RSK modification. Copper-catalyzed conjugation of an azidoalkyl reporter (the click reaction) revealed that fmk-pa achieves selective and saturable modification of endogenous RSK1 and RSK2 in mammalian cells. Saturating concentrations of fmk-pa inhibited Ser386 phosphorylation and downstream signaling in response to phorbol ester stimulation, but had no effect on RSK activation by lipopolysaccharide. RSK autoactivation by the CTD is therefore context dependent, which suggests that NTD and CTD inhibitors should have distinct physiological effects.
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Affiliation(s)
- Michael S Cohen
- Program in Chemistry and Chemical Biology, and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158-2280, USA
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49
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Song T, Sugimoto K, Ihara H, Mizutani A, Hatano N, Kume K, Kambe T, Yamaguchi F, Tokuda M, Watanabe Y. p90 RSK-1 associates with and inhibits neuronal nitric oxide synthase. Biochem J 2007; 401:391-8. [PMID: 16984226 PMCID: PMC1820814 DOI: 10.1042/bj20060580] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 09/15/2006] [Accepted: 09/19/2006] [Indexed: 11/17/2022]
Abstract
Evidence is presented that RSK1 (ribosomal S6 kinase 1), a downstream target of MAPK (mitogen-activated protein kinase), directly phosphorylates nNOS (neuronal nitric oxide synthase) on Ser847 in response to mitogens. The phosphorylation thus increases greatly following EGF (epidermal growth factor) treatment of rat pituitary tumour GH3 cells and is reduced by exposure to the MEK (MAPK/extracellular-signal-regulated kinase kinase) inhibitor PD98059. Furthermore, it is significantly enhanced by expression of wild-type RSK1 and antagonized by kinase-inactive RSK1 or specific reduction of endogenous RSK1. EGF treatment of HEK-293 (human embryonic kidney) cells, expressing RSK1 and nNOS, led to inhibition of NOS enzyme activity, associated with an increase in phosphorylation of nNOS at Ser847, as is also the case in an in vitro assay. In addition, these phenomena were significantly blocked by treatment with the RSK inhibitor Ro31-8220. Cells expressing mutant nNOS (S847A) proved resistant to phosphorylation and decrease of NOS activity. Within minutes of adding EGF to transfected cells, RSK1 associated with nNOS and subsequently dissociated following more prolonged agonist stimulation. EGF-induced formation of the nNOS-RSK1 complex was significantly decreased by PD98059 treatment. Treatment with EGF further revealed phosphorylation of nNOS on Ser847 in rat hippocampal neurons and cerebellar granule cells. This EGF-induced phosphorylation was partially blocked by PD98059 and Ro31-8220. Together, these data provide substantial evidence that RSK1 associates with and phosphorylates nNOS on Ser847 following mitogen stimulation and suggest a novel role for RSK1 in the regulation of nitric oxide function in brain.
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Key Words
- neuronal nitric oxide synthase
- phosphorylation
- pituitary tumour gh3 cell
- ribosomal s6 kinase
- aicar, 5-amino-4-imidazolecarboxamide riboside
- ampk, amp-activated protein kinase
- bad, bcl-2/bcl-xl-antagonist, causing cell death
- cam, calmodulin
- camkii, ca2+/calmodulin-dependent protein kinase ii
- div, days in vitro
- dtt, dithiothreitol
- egf, epidermal growth factor
- erk, extracellular-signal-regulated kinase
- gh, growth hormone
- ha, haemagglutinin
- hek-293, human embryonic kidney
- ibmx, isobutylmethylxanthine
- mapk, mitogen-activated protein kinase
- mek, mapk/erk kinase
- mem, minimum essential medium
- nmda, n-methyl-d-aspartate
- nnos, neuronal nitric oxide synthase
- nos, nitric oxide synthase
- pkc, protein kinase c
- prl, prolactin
- psd, postsynaptic density
- pser, phosphoserine
- rnai, rna interference
- rsk, ribosomal s6 kinase
- sirna, small interfering rna
- wt, wild-type
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Affiliation(s)
- Tao Song
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
- †Department of Anesthesiology, The First Affiliated Hospital, China Medical University, Shenyang 110001, China
| | - Katsuyoshi Sugimoto
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
| | - Hideshi Ihara
- ‡Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Akihiro Mizutani
- §Division of Molecular Neurobiology, Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Naoya Hatano
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
| | - Kodai Kume
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
| | - Toshie Kambe
- ¶Department of Pharmacology, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Fuminori Yamaguchi
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
| | - Masaaki Tokuda
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
| | - Yasuo Watanabe
- *Department of Cell Physiology, Kagawa University, Faculty of Medicine, Kagawa 761-0793, Japan
- ¶Department of Pharmacology, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
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50
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Smyk A, Szuminska M, Uniewicz KA, Graves LM, Kozlowski P. Human enhancer of rudimentary is a molecular partner of PDIP46/SKAR, a protein interacting with DNA polymerase delta and S6K1 and regulating cell growth. FEBS J 2006; 273:4728-41. [PMID: 16984396 DOI: 10.1111/j.1742-4658.2006.05477.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Enhancer of rudimentary (ER) is a small protein that has a unique amino acid sequence and structure. Its highly conserved gene has been found in all eukaryotic kingdoms with the exception of fungi. ER was proposed to be involved in the metabolism of pyrimidines and was reported to act as a transcriptional repressor in a cell type-specific manner. To further elucidate ER functions, we performed the yeast two-hybrid screen of the human lung cDNA library for clones encoding proteins interacting with the human ER protein. The screen yielded polymerase delta interacting protein 46 or S6K1 Aly/REF-like target (PDIP46/SKAR), a protein possessing one RNA recognition motif (RRM) and being a protein partner of both the p50 subunit of DNA polymerase delta and p70 ribosomal protein S6 kinase 1 (S6K1). This interaction was further confirmed in vitro by the glutathione S-transferase-ER pull-down of a protein of 46 kDa from a nuclear extract from human cells which was identified as PDIP46/SKAR by tandem mass spectrometry. The bipartite region of PDIP46/SKAR interacting with ER comprising residues 274-421 encompasses the docking site for S6K1 within the RRM and two serines phosphorylated by S6K1. ER and both isoforms of PDIP46/SKAR share the same nuclear localization in the mammalian cells and their genes display a ubiquitous pattern of expression in a variety of human tissues, so the interaction between ER and PDIP46/SKAR has an opportunity to occur universally in mammalian cells. Because PDIP46/SKAR is involved in the regulation of cell growth its interaction with ER may suggest some function for ER in that control.
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Affiliation(s)
- Amelia Smyk
- Institute of Biochemistry, Warsaw University, Warsaw, Poland
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