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Danieli A, Vucak G, Baccarini M, Martens S. Sequestration of translation initiation factors in p62 condensates. Cell Rep 2023; 42:113583. [PMID: 38096057 DOI: 10.1016/j.celrep.2023.113583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 10/20/2023] [Accepted: 11/29/2023] [Indexed: 12/30/2023] Open
Abstract
Selective autophagy mediates the removal of harmful material from the cytoplasm. This cargo material is selected by cargo receptors, which orchestrate its sequestration within double-membrane autophagosomes and subsequent lysosomal degradation. The cargo receptor p62/SQSTM1 is present in cytoplasmic condensates, and a fraction of them are constantly delivered into lysosomes. However, the molecular composition of the p62 condensates is incompletely understood. To obtain insights into their composition, we develop a method to isolate these condensates and find that p62 condensates are enriched in components of the translation machinery. Furthermore, p62 interacts with translation initiation factors, and eukaryotic initiation factor 2α (eIF2α) and eIF4E are degraded by autophagy in a p62-dependent manner. Thus, p62-mediated autophagy may in part be linked to down-regulation of translation initiation. The p62 condensate isolation protocol developed here may facilitate the study of their contribution to cellular quality control and their roles in health and disease.
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Affiliation(s)
- Alberto Danieli
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria; University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell Biology, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Campus-Vienna-Biocenter 1, 1030 Vienna, Austria.
| | - Georg Vucak
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Campus-Vienna-Biocenter 1, 1030 Vienna, Austria; University of Vienna, Center for Molecular Biology, Department of Microbiology, Immunobiology and Genetics, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Manuela Baccarini
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria; University of Vienna, Center for Molecular Biology, Department of Microbiology, Immunobiology and Genetics, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Sascha Martens
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria; University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell Biology, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria.
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2
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Dorard C, Madry C, Buhard O, Toifl S, Didusch S, Ratovomanana T, Letourneur Q, Dolznig H, Garnett MJ, Duval A, Baccarini M. RAF1 contributes to cell proliferation and STAT3 activation in colorectal cancer independently of microsatellite and KRAS status. Oncogene 2023; 42:1649-1660. [PMID: 37020037 PMCID: PMC10181936 DOI: 10.1038/s41388-023-02683-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/09/2023] [Accepted: 03/24/2023] [Indexed: 04/07/2023]
Abstract
More than 30% of all human cancers are driven by RAS mutations and activating KRAS mutations are present in 40% of colorectal cancer (CRC) in the two main CRC subgroups, MSS (Microsatellite Stable) and MSI (Microsatellite Instable). Studies in RAS-driven tumors have shown essential roles of the RAS effectors RAF and specifically of RAF1, which can be dependent or independent of RAF's ability to activate the MEK/ERK module. In this study, we demonstrate that RAF1, but not its kinase activity, plays a crucial role in the proliferation of both MSI and MSS CRC cell line-derived spheroids and patient-derived organoids, and independently of KRAS mutation status. Moreover, we could define a RAF1 transcriptomic signature which includes genes that contribute to STAT3 activation, and could demonstrate that RAF1 ablation decreases STAT3 phosphorylation in all CRC spheroids tested. The genes involved in STAT3 activation as well as STAT3 targets promoting angiogenesis were also downregulated in human primary tumors expressing low levels of RAF1. These results indicate that RAF1 could be an attractive therapeutic target in both MSI and MSS CRC regardless of their KRAS status and support the development of selective RAF1 degraders rather than RAF1 inhibitors for clinical use in combination therapies.
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Affiliation(s)
- Coralie Dorard
- Department of Microbiology, Immunology and Genetics, Center of Molecular Biology, University of Vienna, Max Perutz Labs, Doktor-Bohr-Gasse 9, 1030, Vienna, Austria.
- Sorbonne Université, INSERM, Unité Mixte de Recherche Scientifique 938 and SIRIC CURAMUS, Centre de Recherche Saint-Antoine (CRSA), Equipe Instabilité des Microsatellites et Cancer, Equipe Labellisée par la Ligue Nationale Contre le Cancer, F-75012, Paris, France.
| | - Claire Madry
- Sorbonne Université, INSERM, Unité Mixte de Recherche Scientifique 938 and SIRIC CURAMUS, Centre de Recherche Saint-Antoine (CRSA), Equipe Instabilité des Microsatellites et Cancer, Equipe Labellisée par la Ligue Nationale Contre le Cancer, F-75012, Paris, France
| | - Olivier Buhard
- Sorbonne Université, INSERM, Unité Mixte de Recherche Scientifique 938 and SIRIC CURAMUS, Centre de Recherche Saint-Antoine (CRSA), Equipe Instabilité des Microsatellites et Cancer, Equipe Labellisée par la Ligue Nationale Contre le Cancer, F-75012, Paris, France
| | - Stefanie Toifl
- Department of Microbiology, Immunology and Genetics, Center of Molecular Biology, University of Vienna, Max Perutz Labs, Doktor-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Sebastian Didusch
- Department of Microbiology, Immunology and Genetics, Center of Molecular Biology, University of Vienna, Max Perutz Labs, Doktor-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Toky Ratovomanana
- Sorbonne Université, INSERM, Unité Mixte de Recherche Scientifique 938 and SIRIC CURAMUS, Centre de Recherche Saint-Antoine (CRSA), Equipe Instabilité des Microsatellites et Cancer, Equipe Labellisée par la Ligue Nationale Contre le Cancer, F-75012, Paris, France
| | - Quentin Letourneur
- Sorbonne Université, INSERM, Unité Mixte de Recherche Scientifique 938 and SIRIC CURAMUS, Centre de Recherche Saint-Antoine (CRSA), Equipe Instabilité des Microsatellites et Cancer, Equipe Labellisée par la Ligue Nationale Contre le Cancer, F-75012, Paris, France
| | - Helmut Dolznig
- Institute of Medical Genetics, Medical University of Vienna, Waehringer Straße 10, A-1090, Vienna, Austria
| | | | - Alex Duval
- Sorbonne Université, INSERM, Unité Mixte de Recherche Scientifique 938 and SIRIC CURAMUS, Centre de Recherche Saint-Antoine (CRSA), Equipe Instabilité des Microsatellites et Cancer, Equipe Labellisée par la Ligue Nationale Contre le Cancer, F-75012, Paris, France
| | - Manuela Baccarini
- Department of Microbiology, Immunology and Genetics, Center of Molecular Biology, University of Vienna, Max Perutz Labs, Doktor-Bohr-Gasse 9, 1030, Vienna, Austria
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3
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Baccarini M. Editor Profile: Manuela Baccarini. FEBS J 2023; 290:73-75. [PMID: 35332671 DOI: 10.1111/febs.16423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this special interview series, we profile members of The FEBS Journal editorial board to highlight their research focus, perspectives on the journal and future directions in their field. Manuela Baccarini is Professor of Cell Signaling at the University of Vienna, Coordinator of the International PhD Program 'Signaling Mechanisms in Cellular Homeostasis' and Director of the Vienna BioCenter PhD Program, a graduate school of the University and Medical University of Vienna in collaboration with the Institute of Molecular Pathology and the Austrian Academy of Sciences, Institute for Medical Biotechnology and Gregor Mendel Institute, as well as EMBO member and corresponding member of the Austrian Academy of Sciences. She has served as an editorial board member of The FEBS Journal since 2016.
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Affiliation(s)
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- The FEBS Journal Editorial Office, Cambridge, UK
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4
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Desideri E, Castelli S, Dorard C, Toifl S, Grazi GL, Ciriolo MR, Baccarini M. Impaired degradation of YAP1 and IL6ST by chaperone-mediated autophagy promotes proliferation and migration of normal and hepatocellular carcinoma cells. Autophagy 2023; 19:152-162. [PMID: 35435804 PMCID: PMC9809932 DOI: 10.1080/15548627.2022.2063004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 04/02/2022] [Accepted: 04/04/2022] [Indexed: 01/07/2023] Open
Abstract
Impaired degradation of the transcriptional coactivator YAP1 and IL6ST (interleukin 6 cytokine family signal transducer), two proteins deregulated in liver cancer, has been shown to promote tumor growth. Here, we demonstrate that YAP1 and IL6ST are novel substrates of chaperone-mediated autophagy (CMA) in human hepatocellular carcinoma (HCC) and hepatocyte cell lines. Knockdown of the lysosomal CMA receptor LAMP2A increases protein levels of YAP1 and IL6ST, without changes in mRNA expression. Additionally, both proteins show KFERQ-dependent binding to the CMA chaperone HSPA8 and accumulate into isolated lysosomes after stimulation of CMA by prolonged starvation. We further show that LAMP2A downregulation promotes the proliferation and migration in HCC cells and a human hepatocyte cell line, and that it does so in a YAP1- and IL6ST-dependent manner. Finally, LAMP2A expression is downregulated, and YAP1 and IL6ST expression is upregulated, in human HCC biopsies. Taken together, our work reveals a novel mechanism that controls the turnover of two cancer-relevant proteins and suggests a tumor suppressor function of CMA in the liver, advocating for the exploitation of CMA activity for diagnostic and therapeutic purposes.Abbreviations: ACTB: actin beta; ATG5: autophagy related 5; ATG7: autophagy related 7; CMA: chaperone-mediated autophagy; eMI: endosomal microautophagy; HCC: hepatocellular carcinoma; HSPA8: heat shock protein family A (Hsp70) member 8; IL6ST: interleukin 6 cytokine family signal transducer; JAK: Janus kinase; LAMP1: lysosomal associated membrane protein 1; LAMP2A: lysosomal associated membrane protein 2A; MAPK8: mitogen-activated protein kinase 8; P6: pyridine 6; SQSTM1: sequestosome 1; TUBA: tubulin alpha; VDAC1: voltage dependent anion channel 1; VP: verteporfin; YAP1: Yes1 associated transcriptional regulator.
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Affiliation(s)
- Enrico Desideri
- Department of Biology, University of Rome “Tor Vergata”, Rome, Italy
- Department of Microbiology, Immunology and Genetics; Center of Molecular Biology, University of Vienna; Max Perutz Labs, Vienna, Austria
| | - Serena Castelli
- Department of Biology, University of Rome “Tor Vergata”, Rome, Italy
| | - Coralie Dorard
- Department of Microbiology, Immunology and Genetics; Center of Molecular Biology, University of Vienna; Max Perutz Labs, Vienna, Austria
| | - Stefanie Toifl
- Department of Microbiology, Immunology and Genetics; Center of Molecular Biology, University of Vienna; Max Perutz Labs, Vienna, Austria
| | - Gian Luca Grazi
- Surgery Unit, Department of Clinical and Experimental Oncology, IRCCS - Regina Elena National Cancer InstituteHepato-Pancreato-Biliary, Rome, Italy
| | - Maria Rosa Ciriolo
- Department of Biology, University of Rome “Tor Vergata”, Rome, Italy
- IRCCS San Raffaele Pisana, Rome, Italy
| | - Manuela Baccarini
- Department of Microbiology, Immunology and Genetics; Center of Molecular Biology, University of Vienna; Max Perutz Labs, Vienna, Austria
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5
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Didusch S, Madern M, Hartl M, Baccarini M. amica: an interactive and user-friendly web-platform for the analysis of proteomics data. BMC Genomics 2022; 23:817. [PMID: 36494623 PMCID: PMC9733095 DOI: 10.1186/s12864-022-09058-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Quantitative proteomics has become an increasingly prominent tool in the study of life sciences. A substantial hurdle for many biologists are, however, the intricacies involved in the associated high throughput data analysis. RESULTS In order to facilitate this task for users with limited background knowledge, we have developed amica, a freely available open-source web-based software that accepts proteomic input files from different sources. amica provides quality control, differential expression, biological network and over-representation analysis on the basis of minimal user input. Scientists can use amica's query interface interactively to compare multiple conditions and rapidly identify enriched or depleted proteins. They can visualize their results using customized output graphics, and ultimately export the results in a tab-separated format that can be shared with collaborators. The code for the application, input data and documentation can be accessed online at https://github.com/tbaccata/amica and is also incorporated in the web application. CONCLUSIONS The strong emphasis on dynamic user interactions, the integration of various databases and the option to download processed data, facilitate the analysis of complex proteomic data for both first-time users and experienced bioinformaticians. A freely available version of amica is available at https://bioapps.maxperutzlabs.ac.at/app/amica .
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Affiliation(s)
- Sebastian Didusch
- grid.473822.80000 0005 0375 3232Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria ,grid.22937.3d0000 0000 9259 8492Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria ,grid.10420.370000 0001 2286 1424University of Vienna, Center for Molecular Biology, Department of Microbiology, Immunobiology and Genetics, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Moritz Madern
- grid.473822.80000 0005 0375 3232Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria ,grid.10420.370000 0001 2286 1424University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell Biology, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Markus Hartl
- grid.473822.80000 0005 0375 3232Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria ,grid.10420.370000 0001 2286 1424University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell Biology, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Manuela Baccarini
- grid.473822.80000 0005 0375 3232Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr.-Bohr-Gasse 9, 1030 Vienna, Austria ,grid.10420.370000 0001 2286 1424University of Vienna, Center for Molecular Biology, Department of Microbiology, Immunobiology and Genetics, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria
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6
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Hollósi A, Pászty K, Bunta BL, Bozó T, Kellermayer M, Debreczeni ML, Cervenak L, Baccarini M, Varga A. BRAF increases endothelial cell stiffness through reorganization of the actin cytoskeleton. FASEB J 2022; 36:e22478. [PMID: 35916021 DOI: 10.1096/fj.202200344r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 07/05/2022] [Accepted: 07/19/2022] [Indexed: 11/11/2022]
Abstract
The dynamics of the actin cytoskeleton and its connection to endothelial cell-cell junctions determine the barrier function of endothelial cells. The proper regulation of barrier opening/closing is necessary for the normal function of vessels, and its dysregulation can result in chronic and acute inflammation leading to edema formation. By using atomic force microscopy, we show here that thrombin-induced permeability of human umbilical vein endothelial cells, associated with actin stress fiber formation, stiffens the cell center. The depletion of the MEK/ERK kinase BRAF reduces thrombin-induced permeability prevents stress fiber formation and cell stiffening. The peripheral actin ring becomes stabilized by phosphorylated myosin light chain, while cofilin is excluded from the cell periphery. All these changes can be reverted by the inhibition of ROCK, but not of the MEK/ERK module. We propose that the balance between the binding of cofilin and myosin to F-actin in the cell periphery, which is regulated by the activity of ROCK, determines the local dynamics of actin reorganization, ultimately driving or preventing stress fiber formation.
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Affiliation(s)
- Anna Hollósi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Katalin Pászty
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Bálint Levente Bunta
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Tamás Bozó
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Miklós Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Márta Lídia Debreczeni
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - László Cervenak
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology and Genetics, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Andrea Varga
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
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7
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Scheffler L, Feicht S, Babushku T, Kuhn LB, Ehrenberg S, Frankenberger S, Lehmann FM, Hobeika E, Jungnickel B, Baccarini M, Bornkamm GW, Strobl LJ, Zimber-Strobl U. ERK phosphorylation is RAF independent in naïve and activated B cells but RAF dependent in plasma cell differentiation. Sci Signal 2021; 14:14/682/eabc1648. [PMID: 33975980 DOI: 10.1126/scisignal.abc1648] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Members of the RAF family of serine-threonine kinases are intermediates in the mitogen-activated protein kinase and extracellular signal-regulated kinase (MAPK-ERK) signaling pathway, which controls key differentiation processes in B cells. By analyzing mice with B cell-specific deletion of Raf1, Braf, or both, we showed that Raf-1 and B-Raf acted together in mediating the positive selection of pre-B and transitional B cells as well as in initiating plasma cell differentiation. However, genetic or chemical inactivation of RAFs led to increased ERK phosphorylation in mature B cells. ERK activation in the absence of Raf-1 and B-Raf was mediated by multiple RAF-independent pathways, with phosphoinositide 3-kinase (PI3K) playing an important role. Furthermore, we found that ERK phosphorylation strongly increased during the transition from activated B cells to pre-plasmablasts. This increase in ERK phosphorylation did not occur in B cells lacking both Raf-1 and B-Raf, which most likely explains the partial block of plasma cell differentiation in mice lacking both RAFs. Collectively, our data indicate that B-Raf and Raf-1 are not necessary to mediate ERK phosphorylation in naïve or activated B cells but are essential for mediating the marked increase in ERK phosphorylation during the transition from activated B cells to pre-plasmablasts.
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Affiliation(s)
- Laura Scheffler
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Samantha Feicht
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany.,Institute for Clinical Molecular Biology and Tumor Genetics, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Tea Babushku
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Laura B Kuhn
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Stefanie Ehrenberg
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Samantha Frankenberger
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Frank M Lehmann
- Institute for Clinical Molecular Biology and Tumor Genetics, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Elias Hobeika
- Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, D-79108 Freiburg, Germany.,Institute of Immunology, Ulm University Medical Center, Albert-Einstein-Allee 11, D-89070 Ulm, Germany
| | - Berit Jungnickel
- Institute for Clinical Molecular Biology and Tumor Genetics, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany.,Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University Jena, Hans-Knoell-Strasse 2, D-07745 Jena, Germany
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology, and Genetics, Center for Molecular Biology of the University of Vienna, Max Perutz Labs, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Georg W Bornkamm
- Institute for Clinical Molecular Biology and Tumor Genetics, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Lothar J Strobl
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Ursula Zimber-Strobl
- Research Unit of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Marchioninistrasse 25, D-81377 Munich, Germany.
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8
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Elgendy M, Cirò M, Hosseini A, Weiszmann J, Mazzarella L, Ferrari E, Cazzoli R, Curigliano G, DeCensi A, Bonanni B, Budillon A, Pelicci PG, Janssens V, Ogris M, Baccarini M, Lanfrancone L, Weckwerth W, Foiani M, Minucci S. Combination of Hypoglycemia and Metformin Impairs Tumor Metabolic Plasticity and Growth by Modulating the PP2A-GSK3β-MCL-1 Axis. Cancer Cell 2019; 35:798-815.e5. [PMID: 31031016 DOI: 10.1016/j.ccell.2019.03.007] [Citation(s) in RCA: 189] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 01/05/2019] [Accepted: 03/27/2019] [Indexed: 01/09/2023]
Abstract
Tumor cells may adapt to metabolic challenges by alternating between glycolysis and oxidative phosphorylation (OXPHOS). To target this metabolic plasticity, we combined intermittent fasting, a clinically feasible approach to reduce glucose availability, with the OXPHOS inhibitor metformin. In mice exposed to 24-h feeding/fasting cycles, metformin impaired tumor growth only when administered during fasting-induced hypoglycemia. Synergistic anti-neoplastic effects of the metformin/hypoglycemia combination were mediated by glycogen synthase kinase 3β (GSK3β) activation downstream of PP2A, leading to a decline in the pro-survival protein MCL-1, and cell death. Mechanistically, specific activation of the PP2A-GSK3β axis was the sum of metformin-induced inhibition of CIP2A, a PP2A suppressor, and of upregulation of the PP2A regulatory subunit B56δ by low glucose, leading to an active PP2A-B56δ complex with high affinity toward GSK3β.
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Affiliation(s)
- Mohamed Elgendy
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy.
| | - Marco Cirò
- Experimental Therapeutics Program, IFOM - The FIRC Institute for Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Amir Hosseini
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy
| | - Jakob Weiszmann
- Department of Ecogenomics and Systems Biology, Faculty of Sciences, University of Vienna, Vienna, Austria; Vienna Metabolomics Center (VIME), University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Luca Mazzarella
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy
| | - Elisa Ferrari
- Experimental Therapeutics Program, IFOM - The FIRC Institute for Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Riccardo Cazzoli
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy
| | - Giuseppe Curigliano
- Division of Early Drug Development, IEO, European Institute of Oncology IRCCS, Milan, Italy
| | - Andrea DeCensi
- Medical Oncology Unit, Ospedali Galliera, 16128 Genova, Italy
| | - Bernardo Bonanni
- Division of Cancer Prevention and Genetics, IEO, European Institute of Oncology IRCCS, Milan, Italy
| | - Alfredo Budillon
- Experimental Pharmacology Unit, Laboratori di Mercogliano, Istituto Nazionale Tumori, IRCCS-Fondazione G. Pascale, Napoli, Italy
| | - Pier Giuseppe Pelicci
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy; Department of Oncology and Hemato-Oncology, Università Degli Studi di Milano, Milan, Italy
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Manfred Ogris
- Laboratory of MacroMolecular Cancer Therapeutics (MMCT), Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology and Genetics, Center for Molecular Biology of the University of Vienna, Max F. Perutz Laboratories, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Luisa Lanfrancone
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy
| | - Wolfram Weckwerth
- Department of Ecogenomics and Systems Biology, Faculty of Sciences, University of Vienna, Vienna, Austria; Vienna Metabolomics Center (VIME), University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Marco Foiani
- Experimental Therapeutics Program, IFOM - The FIRC Institute for Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy; Department of Oncology and Hemato-Oncology, Università Degli Studi di Milano, Milan, Italy
| | - Saverio Minucci
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy; Department of Biosciences, University of Milan, 20100 Milan, Italy.
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9
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Dorard C, Cseh B, Ehrenreiter K, Wimmer R, Varga A, Hirschmugl T, Maier B, Kramer K, Fürlinger S, Doma E, Baccarini M. RAF dimers control vascular permeability and cytoskeletal rearrangements at endothelial cell-cell junctions. FEBS J 2019; 286:2277-2294. [PMID: 30828992 PMCID: PMC6617973 DOI: 10.1111/febs.14802] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/17/2019] [Accepted: 03/01/2019] [Indexed: 01/07/2023]
Abstract
The endothelium functions as a semipermeable barrier regulating fluid homeostasis, nutrient, and gas supply to the tissue. Endothelial permeability is increased in several pathological conditions including inflammation and tumors; despite its clinical relevance, however, there are no specific therapies preventing vascular leakage. Here, we show that endothelial cell‐restricted ablation of BRAF, a kinase frequently activated in cancer, prevents vascular leaking as well metastatic spread. BRAF regulates endothelial permeability by promoting the cytoskeletal rearrangements necessary for the remodeling of VE‐Cadherin‐containing endothelial cell–cell junctions and the formation of intercellular gaps. BRAF kinase activity and the ability to form complexes with RAS/RAP1 and dimers with its paralog RAF1 are required for proper permeability control, achieved mechanistically by modulating the interaction between RAF1 and the RHO effector ROKα. Thus, RAF dimerization impinges on RHO pathways to regulate cytoskeletal rearrangements, junctional plasticity, and endothelial permeability. The data advocate the development of RAF dimerization inhibitors, which would combine tumor cell autonomous effect with stabilization of the vasculature and antimetastatic spread.
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Affiliation(s)
- Coralie Dorard
- Max F. Perutz Laboratories, University of Vienna, Austria
| | - Botond Cseh
- Max F. Perutz Laboratories, University of Vienna, Austria
| | | | - Reiner Wimmer
- Max F. Perutz Laboratories, University of Vienna, Austria
| | - Andrea Varga
- Max F. Perutz Laboratories, University of Vienna, Austria
| | | | - Barbara Maier
- Max F. Perutz Laboratories, University of Vienna, Austria
| | - Karina Kramer
- Max F. Perutz Laboratories, University of Vienna, Austria
| | | | - Eszter Doma
- Max F. Perutz Laboratories, University of Vienna, Austria
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10
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Yuan J, Ng WH, Tian Z, Yap J, Baccarini M, Chen Z, Hu J. Activating mutations in MEK1 enhance homodimerization and promote tumorigenesis. Sci Signal 2018; 11:11/554/eaar6795. [PMID: 30377225 DOI: 10.1126/scisignal.aar6795] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
RAS-RAF-MEK-ERK signaling has a well-defined role in cancer biology. Although aberrant pathway activation occurs mostly upstream of the kinase MEK, mutations in MEK are prevalent in some cancer subsets. Here, we found that cancer-related, activating mutations in MEK can be classified into two groups: those that relieve inhibitory interactions with the helix A region and those that are in-frame deletions of the β3-αC loop, which enhance MEK1 homodimerization. The former, helix A-associated mutants, are inhibited by traditional MEK inhibitors. However, we found that the increased homodimerization associated with the loop-deletion mutants promoted intradimer cross-phosphorylation of the activation loop and conferred differential resistance to MEK inhibitors both in vitro and in vivo. MEK1 dimerization was required both for its activation by the kinase RAF and for its catalytic activity toward the kinase ERK. Our findings not only identify a previously unknown group of MEK mutants and provide insight into some key steps in RAF-MEK-ERK activation but also have implications for the design of therapies targeting RAS-ERK signaling in cancers.
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Affiliation(s)
- Jimin Yuan
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore
| | - Wan Hwa Ng
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore
| | - Zizi Tian
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jiajun Yap
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore
| | - Manuela Baccarini
- Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Zhongzhou Chen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jiancheng Hu
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore. .,Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857 Singapore, Singapore
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11
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Yuan J, Ng WH, Lam PYP, Wang Y, Xia H, Yap J, Guan SP, Lee ASG, Wang M, Baccarini M, Hu J. The dimer-dependent catalytic activity of RAF family kinases is revealed through characterizing their oncogenic mutants. Oncogene 2018; 37:5719-5734. [PMID: 29930381 PMCID: PMC6202329 DOI: 10.1038/s41388-018-0365-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 12/19/2022]
Abstract
Although extensively studied for three decades, the molecular mechanisms that regulate the RAF/MEK/ERK kinase cascade remain ambiguous. Recent studies identified the dimerization of RAF as a key event in the activation of this cascade. Here, we show that in-frame deletions in the β3-αC loop activate ARAF as well as BRAF and other oncogenic kinases by enforcing homodimerization. By characterizing these RAF mutants, we find that ARAF has less allosteric and catalytic activity than the other two RAF isoforms, which arises from its non-canonical APE motif. Further, these RAF mutants exhibit a strong oncogenic potential, and a differential inhibitor resistance that correlates with their dimer affinity. Using these unique mutants, we demonstrate that active RAFs, including the BRAF(V600E) mutant, phosphorylate MEK in a dimer-dependent manner. This study characterizes a special category of oncogenic kinase mutations, and elucidates the molecular basis that underlies the differential ability of RAF isoforms to stimulate MEK-ERK pathway. Further, this study reveals a unique catalytic feature of RAF family kinases that can be exploited to control their activities for cancer therapies.
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Affiliation(s)
- Jimin Yuan
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Wan Hwa Ng
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Paula Y P Lam
- Division of Cellular and Molecular Research, Singapore, Singapore.,Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Yu Wang
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Hongping Xia
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Jiajun Yap
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Shou Ping Guan
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Ann S G Lee
- Division of Medical Sciences, National Cancer Centre Singapore, 11 Hospital Drive, Singapore, 169610, Singapore.,Office of Clinical & Academic Faculty Affairs, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore.,Department of Physiology, National University of Singapore, 2 Medical Drive, 117597, Singapore, Singapore
| | - Mei Wang
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Manuela Baccarini
- Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Jiancheng Hu
- Division of Cellular and Molecular Research, Singapore, Singapore. .,Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore, Singapore.
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12
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Baumgartner C, Toifl S, Farlik M, Halbritter F, Scheicher R, Fischer I, Sexl V, Bock C, Baccarini M. An ERK-Dependent Feedback Mechanism Prevents Hematopoietic Stem Cell Exhaustion. Cell Stem Cell 2018; 22:879-892.e6. [PMID: 29804890 PMCID: PMC5988582 DOI: 10.1016/j.stem.2018.05.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/08/2018] [Accepted: 05/04/2018] [Indexed: 11/22/2022]
Abstract
Hematopoietic stem cells (HSCs) sustain hematopoiesis throughout life. HSCs exit dormancy to restore hemostasis in response to stressful events, such as acute blood loss, and must return to a quiescent state to prevent their exhaustion and resulting bone marrow failure. HSC activation is driven in part through the phosphatidylinositol 3-kinase (PI3K)/AKT/mTORC1 signaling pathway, but less is known about the cell-intrinsic pathways that control HSC dormancy. Here, we delineate an ERK-dependent, rate-limiting feedback mechanism that controls HSC fitness and their re-entry into quiescence. We show that the MEK/ERK and PI3K pathways are synchronously activated in HSCs during emergency hematopoiesis and that feedback phosphorylation of MEK1 by activated ERK counterbalances AKT/mTORC1 activation. Genetic or chemical ablation of this feedback loop tilts the balance between HSC dormancy and activation, increasing differentiated cell output and accelerating HSC exhaustion. These results suggest that MEK inhibitors developed for cancer therapy may find additional utility in controlling HSC activation. MEK/ERK and AKT/mTORC1 are reversibly activated during hematopoiesis MEK1 prevents HSC exhaustion during stress hematopoiesis Feedback phosphorylation of MEK1 by ERK limits AKT/mTORC1 activation ERK-mediated MEK1 phosphorylation returns activated HSCs to quiescence
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Affiliation(s)
- Christian Baumgartner
- Department of Microbiology, Immunobiology and Genetics, Center for Molecular Biology of the University of Vienna, Max F. Perutz Laboratories, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Stefanie Toifl
- Department of Microbiology, Immunobiology and Genetics, Center for Molecular Biology of the University of Vienna, Max F. Perutz Laboratories, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Matthias Farlik
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Florian Halbritter
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Ruth Scheicher
- Department for Biomedical Sciences, Institute of Pharmacology and Toxicology, University of Veterinary Medicine, 1210 Vienna, Austria
| | - Irmgard Fischer
- Department of Microbiology, Immunobiology and Genetics, Center for Molecular Biology of the University of Vienna, Max F. Perutz Laboratories, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Veronika Sexl
- Department for Biomedical Sciences, Institute of Pharmacology and Toxicology, University of Veterinary Medicine, 1210 Vienna, Austria
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria; Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria; Saarland Informatics Campus, Max Planck Institute for Informatics, Saarbrücken, Germany
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology and Genetics, Center for Molecular Biology of the University of Vienna, Max F. Perutz Laboratories, Vienna Biocenter (VBC), 1030 Vienna, Austria.
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13
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Nowacka JD, Baumgartner C, Pelorosso C, Roth M, Zuber J, Baccarini M. MEK1 is required for the development of NRAS-driven leukemia. Oncotarget 2018; 7:80113-80130. [PMID: 27741509 PMCID: PMC5348309 DOI: 10.18632/oncotarget.12555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 09/29/2016] [Indexed: 11/25/2022] Open
Abstract
The dual-specificity kinases MEK1 and MEK2 act downstream of RAS/RAF to induce ERK activation, which is generally considered protumorigenic. Activating MEK mutations have not been discovered in leukemia, in which pathway activation is caused by mutations in upstream components such as RAS or Flt3. The anti-leukemic potential of MEK inhibitors is being tested in clinical trials; however, downregulation of MEK1 promotes Eμ-Myc-driven lymphomagenesis and MEK1 ablation induces myeloproliferative disease in mice, raising the concern that MEK inhibitors may be inefficient or counterproductive in this context. We investigated the role of MEK1 in the proliferation of human leukemic cell lines and in retroviral models of leukemia. Our data show that MEK1 suppression via RNA interference and genomic engineering does not affect the proliferation of human leukemic cell lines in culture; similarly, MEK1 ablation does not impact the development of MYC-driven leukemia in vivo. In contrast, MEK1 ablation significantly reduces tumorigenesis driven by Nras alone or in combination with Myc. Thus, while MEK1 restricts proliferation and tumorigenesis in some cellular and genetic contexts, it cannot be considered a tumor suppressor in the context of leukemogenesis. On the contrary, its role in NRAS-driven leukemogenesis advocates the use of MEK inhibitors, particularly in combination with PI3K/AKT inhibitors, in hematopoietic malignancies involving RAS activation.
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Affiliation(s)
- Joanna D Nowacka
- Department of Microbiology and Immunobiology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Christian Baumgartner
- Department of Microbiology and Immunobiology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Cristiana Pelorosso
- Department of Microbiology and Immunobiology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.,Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital-University of Florence, Florence, Italy
| | - Mareike Roth
- Research Institute of Molecular Pathology, Vienna, Austria
| | - Johannes Zuber
- Research Institute of Molecular Pathology, Vienna, Austria
| | - Manuela Baccarini
- Department of Microbiology and Immunobiology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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14
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Dorard C, Estrada C, Barbotin C, Larcher M, Garancher A, Leloup J, Beermann F, Baccarini M, Pouponnot C, Larue L, Eychène A, Druillennec S. RAF proteins exert both specific and compensatory functions during tumour progression of NRAS-driven melanoma. Nat Commun 2017; 8:15262. [PMID: 28497782 PMCID: PMC5437303 DOI: 10.1038/ncomms15262] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 03/14/2017] [Indexed: 12/19/2022] Open
Abstract
NRAS and its effector BRAF are frequently mutated in melanoma. Paradoxically, CRAF but not BRAF was shown to be critical for various RAS-driven cancers, raising the question of the role of RAF proteins in NRAS-induced melanoma. Here, using conditional ablation of Raf genes in NRAS-induced mouse melanoma models, we investigate their contribution in tumour progression, from the onset of benign tumours to malignant tumour maintenance. We show that BRAF expression is required for ERK activation and nevi development, demonstrating a critical role in the early stages of NRAS-driven melanoma. After melanoma formation, single Braf or Craf ablation is not sufficient to block tumour growth, showing redundant functions for RAF kinases. Finally, proliferation of resistant cells emerging in the absence of BRAF and CRAF remains dependent on ARAF-mediated ERK activation. These results reveal specific and compensatory functions for BRAF and CRAF and highlight an addiction to RAF signalling in NRAS-driven melanoma. The melanoma-driver mutations in NRAS and BRAF are mutually exclusive but the contribution of RAF signalling downstream of NRAS remains to be clarified. Here, using mouse models, the authors show specific roles of each member of the RAF family at different stages of melanomagenesis.
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Affiliation(s)
- Coralie Dorard
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Charlène Estrada
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Céline Barbotin
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Magalie Larcher
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Alexandra Garancher
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France
| | - Jessy Leloup
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Friedrich Beermann
- Swiss Institute for Experimental Cancer Research (ISREC), Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
| | - Manuela Baccarini
- Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, Vienna 1030, Austria
| | - Celio Pouponnot
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France
| | - Lionel Larue
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Alain Eychène
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
| | - Sabine Druillennec
- Institut Curie, Orsay F-91405, France.,INSERM U1021, Centre Universitaire, Orsay F-91405, France.,CNRS UMR 3347, Centre Universitaire, Orsay F-91405, France.,Université Paris Sud-11, Orsay F-91405, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Orsay F-91405, France
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15
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Varga A, Ehrenreiter K, Aschenbrenner B, Kocieniewski P, Kochanczyk M, Lipniacki T, Baccarini M. RAF1/BRAF dimerization integrates the signal from RAS to ERK and ROKα. Sci Signal 2017; 10:10/469/eaai8482. [PMID: 28270557 DOI: 10.1126/scisignal.aai8482] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Downstream of growth factor receptors and of the guanine triphosphatase (GTPase) RAS, heterodimers of the serine/threonine kinases BRAF and RAF1 are critical upstream kinases and activators of the mitogen-activated protein kinase (MAPK) module containing the mitogen-activated and extracellular signal-regulated kinase kinase (MEK) and their targets, the extracellular signal-regulated kinase (ERK) family. Either direct or scaffold protein-mediated interactions among the components of the ERK module (the MAPKKKs BRAF and RAF1, MEK, and ERK) facilitate signal transmission. RAF1 also has essential functions in the control of tumorigenesis and migration that are mediated through its interaction with the kinase ROKα, an effector of the GTPase RHO and regulator of cytoskeletal rearrangements. We combined mutational and kinetic analysis with mathematical modeling to show that the interaction of RAF1 with ROKα is coordinated with the role of RAF1 in the ERK pathway. We found that the phosphorylated form of RAF1 that interacted with and inhibited ROKα was generated during the interaction of RAF1 with the ERK module. This mechanism adds plasticity to the ERK pathway, enabling signal diversification at the level of both ERK and RAF. Furthermore, by connecting ERK activation with the regulation of ROKα and cytoskeletal rearrangements by RAF1, this mechanism has the potential to precisely coordinate the proper timing of proliferation with changes in cell shape, adhesion, or motility.
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Affiliation(s)
- Andrea Varga
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Karin Ehrenreiter
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Bertram Aschenbrenner
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Pawel Kocieniewski
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - Marek Kochanczyk
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - Tomasz Lipniacki
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - Manuela Baccarini
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.
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16
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Papaioannou G, Petit ET, Liu ES, Baccarini M, Pritchard C, Demay MB. Raf Kinases Are Essential for Phosphate Induction of ERK1/2 Phosphorylation in Hypertrophic Chondrocytes and Normal Endochondral Bone Development. J Biol Chem 2017; 292:3164-3171. [PMID: 28073913 DOI: 10.1074/jbc.m116.763342] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/04/2017] [Indexed: 01/18/2023] Open
Abstract
Hypophosphatemia causes rickets by impairing hypertrophic chondrocyte apoptosis. Phosphate induction of MEK1/2-ERK1/2 phosphorylation in hypertrophic chondrocytes is required for phosphate-mediated apoptosis and growth plate maturation. MEK1/2 can be activated by numerous molecules including Raf isoforms. A- and B-Raf ablation in chondrocytes does not alter skeletal development, whereas ablation of C-Raf decreases hypertrophic chondrocyte apoptosis and impairs vascularization of the growth plate. However, ablation of C-Raf does not impair phosphate-induced ERK1/2 phosphorylation in vitro, but leads to rickets by decreasing VEGF protein stability. To determine whether Raf isoforms are required for phosphate-induced hypertrophic chondrocyte apoptosis, mice lacking all three Raf isoforms in chondrocytes were generated. Raf deletion caused neonatal death and a significant expansion of the hypertrophic chondrocyte layer of the growth plate, accompanied by decreased cleaved caspase-9. This was associated with decreased phospho-ERK1/2 immunoreactivity in the hypertrophic chondrocyte layer and impaired vascular invasion. These data further demonstrated that Raf kinases are required for phosphate-induced ERK1/2 phosphorylation in cultured hypertrophic chondrocytes and perform essential, but partially redundant roles in growth plate maturation.
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Affiliation(s)
- Garyfallia Papaioannou
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard Medical School, Boston, Massachusetts 02115
| | - Elizabeth T Petit
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Eva S Liu
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard Medical School, Boston, Massachusetts 02115; Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology and Genetics, Center of Molecular Biology, Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, Vienna 1030, Austria
| | - Catrin Pritchard
- Department of Molecular and Cell Biology, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard Medical School, Boston, Massachusetts 02115.
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17
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Raguz J, Jeric I, Niault T, Nowacka JD, Kuzet SE, Rupp C, Fischer I, Biggi S, Borsello T, Baccarini M. Epidermal RAF prevents allergic skin disease. eLife 2016; 5. [PMID: 27431613 PMCID: PMC4951198 DOI: 10.7554/elife.14012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 06/13/2016] [Indexed: 01/08/2023] Open
Abstract
The RAS pathway is central to epidermal homeostasis, and its activation in tumors or in Rasopathies correlates with hyperproliferation. Downstream of RAS, RAF kinases are actionable targets regulating keratinocyte turnover; however, chemical RAF inhibitors paradoxically activate the pathway, promoting epidermal proliferation. We generated mice with compound epidermis-restricted BRAF/RAF1 ablation. In these animals, transient barrier defects and production of chemokines and Th2-type cytokines by keratinocytes cause a disease akin to human atopic dermatitis, characterized by IgE responses and local and systemic inflammation. Mechanistically, BRAF and RAF1 operate independently to balance MAPK signaling: BRAF promotes ERK activation, while RAF1 dims stress kinase activation. In vivo, JNK inhibition prevents disease onset, while MEK/ERK inhibition in mice lacking epidermal RAF1 phenocopies it. These results support a primary role of keratinocytes in the pathogenesis of atopic dermatitis, and the animals lacking BRAF and RAF1 in the epidermis represent a useful model for this disease.
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Affiliation(s)
- Josipa Raguz
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Ines Jeric
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Theodora Niault
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Joanna Daniela Nowacka
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Sanya Eduarda Kuzet
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Christian Rupp
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Irmgard Fischer
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Silvia Biggi
- Department of Neuroscience, Istituto Di Ricerche Farmacologiche Mario Negri, Milano, Italy.,Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milano, Italy
| | - Tiziana Borsello
- Department of Neuroscience, Istituto Di Ricerche Farmacologiche Mario Negri, Milano, Italy.,Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milano, Italy
| | - Manuela Baccarini
- Department of Microbiology, Immunology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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18
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Baccarini M, Dikic I. Editorial overview: Cell regulation. Curr Opin Cell Biol 2016; 39:iv-vi. [PMID: 27017261 DOI: 10.1016/j.ceb.2016.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Manuela Baccarini
- Center for Molecular Biology, University of Vienna, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9/4, A-1030 Vienna, Austria.
| | - Ivan Dikic
- Institute of Biochemistry II, Goethe University School of Medicine, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Riedberg Campus, Max-von-Laue-Straße 15, 60438 Frankfurt am Main, Germany; Institute of Immunology, School of Medicine, University of Split, Mestrovicevo setaliste bb, 21 000 Split, Croatia
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19
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Affiliation(s)
- Andrea Varga
- Center of Molecular Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Manuela Baccarini
- Center of Molecular Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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20
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Liu ES, Raimann A, Chae BT, Martins JS, Baccarini M, Demay MB. c-Raf promotes angiogenesis during normal growth plate maturation. Development 2015; 143:348-55. [PMID: 26657770 DOI: 10.1242/dev.127142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 12/02/2015] [Indexed: 01/18/2023]
Abstract
Extracellular phosphate plays a key role in growth plate maturation by inducing Erk1/2 (Mapk3/1) phosphorylation, leading to hypertrophic chondrocyte apoptosis. The Raf kinases induce Mek1/2 (Map2k1/2) and Erk1/2 phosphorylation; however, a role for Raf kinases in endochondral bone formation has not been identified. Ablation of both A-Raf (Araf) and B-Raf (Braf) in chondrocytes does not alter growth plate maturation. Because c-Raf (Raf1) phosphorylation is increased by extracellular phosphate and c-Raf is the predominant isoform expressed in hypertrophic chondrocytes, chondrocyte-specific c-Raf knockout mice (c-Raf(f/f);ColII-Cre(+)) were generated to define a role for c-Raf in growth plate maturation. In vivo studies demonstrated that loss of c-Raf in chondrocytes leads to expansion of the hypertrophic layer of the growth plate, with decreased phospho-Erk1/2 immunoreactivity and impaired hypertrophic chondrocyte apoptosis. However, cultured hypertrophic chondrocytes from these mice did not exhibit impairment of phosphate-induced Erk1/2 phosphorylation. Studies performed to reconcile the discrepancy between the in vitro and in vivo hypertrophic chondrocyte phenotypes revealed normal chondrocyte differentiation in c-Raf(f/f);ColII-Cre(+) mice and lack of compensatory increase in the expression of A-Raf and B-Raf. However, VEGF (Vegfa) immunoreactivity in the hypertrophic chondrocytes of c-Raf(f/f);ColII-Cre(+) mice was significantly reduced, associated with increased ubiquitylation of VEGF protein. Thus, c-Raf plays an important role in growth plate maturation by regulating vascular invasion, which is crucial for replacement of terminally differentiated hypertrophic chondrocytes by bone.
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Affiliation(s)
- Eva S Liu
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA 02115, USA Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA Harvard Medical School, Boston, MA 02115, USA
| | - Adalbert Raimann
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA Harvard Medical School, Boston, MA 02115, USA Department of Pediatrics and Adolescent Medicine, Medical University Vienna, 1090, Vienna, Austria
| | | | - Janaina S Martins
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA Harvard Medical School, Boston, MA 02115, USA
| | - Manuela Baccarini
- Department of Microbiology, Immunobiology and Genetics, Center of Molecular Biology, Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, Vienna 1030, Austria
| | - Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA Harvard Medical School, Boston, MA 02115, USA
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21
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Affiliation(s)
- Christian Baumgartner
- Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna, Austria
| | - Manuela Baccarini
- Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna, Austria
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22
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Resta G, Scagliarini L, Bandi M, Vedana L, Marzetti A, Ferrocci G, Santini M, Anania G, Cavallesco G, Baccarini M. Sigmoid volvulus: is it a possible complication after stapled transanal rectal resection (STARR)? G Chir 2014; 34:224-6. [PMID: 24091179 DOI: 10.11138/gchir/2013.34.7.224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We report a case of sigmoid volvulus post-stapled transanal rectal resection (STARR) for obstructed defecation. The patient, a 68-yearold woman with chronic constipation and dolichosigma, two days post-STARR presented severe abdominal pain. CT revealed sigmoid ischemia. The patient underwent resection of the sigmoid colon with end colostomy (Hartmann's procedure). Can STARR procedure produce a serious complication as sigmoid volvulus in patient with dolichosigma and obstructed defecation syndrome?
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23
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Vin H, Ojeda SS, Ching G, Leung ML, Chitsazzadeh V, Dwyer DW, Adelmann CH, Restrepo M, Richards KN, Stewart LR, Du L, Ferguson SB, Chakravarti D, Ehrenreiter K, Baccarini M, Ruggieri R, Curry JL, Kim KB, Ciurea AM, Duvic M, Prieto VG, Ullrich SE, Dalby KN, Flores ER, Tsai KY. BRAF inhibitors suppress apoptosis through off-target inhibition of JNK signaling. eLife 2013; 2:e00969. [PMID: 24192036 PMCID: PMC3814616 DOI: 10.7554/elife.00969] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Vemurafenib and dabrafenib selectively inhibit the v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) kinase, resulting in high response rates and increased survival in melanoma. Approximately 22% of individuals treated with vemurafenib develop cutaneous squamous cell carcinoma (cSCC) during therapy. The prevailing explanation for this is drug-induced paradoxical ERK activation, resulting in hyperproliferation. Here we show an unexpected and novel effect of vemurafenib/PLX4720 in suppressing apoptosis through the inhibition of multiple off-target kinases upstream of c-Jun N-terminal kinase (JNK), principally ZAK. JNK signaling is suppressed in multiple contexts, including in cSCC of vemurafenib-treated patients, as well as in mice. Expression of a mutant ZAK that cannot be inhibited reverses the suppression of JNK activation and apoptosis. Our results implicate suppression of JNK-dependent apoptosis as a significant, independent mechanism that cooperates with paradoxical ERK activation to induce cSCC, suggesting broad implications for understanding toxicities associated with BRAF inhibitors and for their use in combination therapies. DOI: http://dx.doi.org/10.7554/eLife.00969.001.
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Affiliation(s)
- Harina Vin
- Department of Immunology, University of Texas MD Anderson Cancer Center, Houston, United States
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24
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Vin H, Ching G, Ojeda SS, Adelmann CH, Chitsazzadeh V, Dwyer DW, Ma H, Ehrenreiter K, Baccarini M, Ruggieri R, Curry JL, Ciurea AM, Duvic M, Busaidy NL, Tannir NM, Tsai KY. Sorafenib suppresses JNK-dependent apoptosis through inhibition of ZAK. Mol Cancer Ther 2013; 13:221-9. [PMID: 24170769 DOI: 10.1158/1535-7163.mct-13-0561] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sorafenib is U.S. Food and Drug Adminstration-approved for the treatment of renal cell carcinoma and hepatocellular carcinoma and has been combined with numerous other targeted therapies and chemotherapies in the treatment of many cancers. Unfortunately, as with other RAF inhibitors, patients treated with sorafenib have a 5% to 10% rate of developing cutaneous squamous cell carcinoma (cSCC)/keratoacanthomas. Paradoxical activation of extracellular signal-regulated kinase (ERK) in BRAF wild-type cells has been implicated in RAF inhibitor-induced cSCC. Here, we report that sorafenib suppresses UV-induced apoptosis specifically by inhibiting c-jun-NH(2)-kinase (JNK) activation through the off-target inhibition of leucine zipper and sterile alpha motif-containing kinase (ZAK). Our results implicate suppression of JNK signaling, independent of the ERK pathway, as an additional mechanism of adverse effects of sorafenib. This has broad implications for combination therapies using sorafenib with other modalities that induce apoptosis.
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Affiliation(s)
- Harina Vin
- Corresponding Author: Kenneth Y. Tsai, Departments of Dermatology and Immunology, University of Texas MD Anderson Cancer Center, 7455 Fannin, Unit 907, Houston, TX 77054.
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25
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Doma E, Rupp C, Varga A, Kern F, Riegler B, Baccarini M. Skin tumorigenesis stimulated by Raf inhibitors relies upon Raf functions that are dependent and independent of ERK. Cancer Res 2013; 73:6926-37. [PMID: 24129679 DOI: 10.1158/0008-5472.can-13-0748] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RAF inhibitors achieve unprecedented but mainly transient clinical responses in patients with melanoma whose tumors harbor an activating BRAF mutation. One notable side-effect of RAF inhibitors is the stimulation of cutaneous skin tumors, arising in about 30% of patients receiving these drugs, which are thought to develop as a result of inhibitor-induced activation of wild-type Raf in occult precursor skin lesions. This effect raises the possibility that less manageable tumors might also arise in other epithelial tissues. Here we provide preclinical evidence supporting this disquieting hypothesis by showing that the RAF inhibitors PLX-4032 (vemurafenib) and GDC-0879 precipitate the development of cell-autonomous, Ras-driven tumors in skin and gastric epithelia. The magnitude of the effects correlated with the inhibitors' relative abilities to induce ERK activation. Epidermis-restricted ablation of either B-Raf or C-Raf prevented PLX-4032-induced ERK activation and tumorigenesis. In contrast, GDC-0879 induced ERK activation and tumorigenesis in B-Raf-deficient epidermis, whereas C-Raf ablation blocked GDC-0879-induced tumorigenesis (despite strong ERK activation) by preventing Rokα-mediated keratinocyte dedifferentiation. Thus, inhibitor-induced ERK activation did not require a specific Raf kinase. ERK activation was necessary, but not sufficient for Ras + Raf inhibitor-induced tumorigenesis, whereas C-Raf downregulation of Rokα was essential even in the face of sustained ERK signaling to prevent differentiation and promote tumorigenesis. Taken together, our findings suggest that combination therapies targeting ERK-dependent and -independent functions of Raf may be more efficient but also safer for cancer treatment.
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Affiliation(s)
- Eszter Doma
- Authors' Affiliation: Department of Microbiology, Immunobiology and Genetics, University of Vienna, Max F. Perutz Laboratories, Vienna, Austria
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26
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Eser S, Reiff N, Messer M, Seidler B, Gottschalk K, Dobler M, Hieber M, Arbeiter A, Klein S, Kong B, Michalski CW, Schlitter AM, Esposito I, Kind AJ, Rad L, Schnieke AE, Baccarini M, Alessi DR, Rad R, Schmid RM, Schneider G, Saur D. Selective requirement of PI3K/PDK1 signaling for Kras oncogene-driven pancreatic cell plasticity and cancer. Cancer Cell 2013; 23:406-20. [PMID: 23453624 DOI: 10.1016/j.ccr.2013.01.023] [Citation(s) in RCA: 266] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 12/27/2012] [Accepted: 01/30/2013] [Indexed: 12/30/2022]
Abstract
Oncogenic Kras activates a plethora of signaling pathways, but our understanding of critical Ras effectors is still very limited. We show that cell-autonomous phosphoinositide 3-kinase (PI3K) and 3-phosphoinositide-dependent protein kinase 1 (PDK1), but not Craf, are key effectors of oncogenic Kras in the pancreas, mediating cell plasticity, acinar-to-ductal metaplasia (ADM), and pancreatic ductal adenocarcinoma (PDAC) formation. This contrasts with Kras-driven non-small cell lung cancer, where signaling via Craf, but not PDK1, is an essential tumor-initiating event. These in vivo genetic studies together with pharmacologic treatment studies in models of human ADM and PDAC demonstrate tissue-specific differences of oncogenic Kras signaling and define PI3K/PDK1 as a suitable target for therapeutic intervention specifically in PDAC.
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Affiliation(s)
- Stefan Eser
- Department of Internal Medicine 2, Technische Universität München, Ismaningerstr. 22, 81675 München, Germany
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27
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Zmajkovicova K, Jesenberger V, Catalanotti F, Baumgartner C, Reyes G, Baccarini M. MEK1 is required for PTEN membrane recruitment, AKT regulation, and the maintenance of peripheral tolerance. Mol Cell 2013; 50:43-55. [PMID: 23453810 PMCID: PMC3625979 DOI: 10.1016/j.molcel.2013.01.037] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 09/13/2012] [Accepted: 01/25/2013] [Indexed: 12/11/2022]
Abstract
The Raf/MEK/ERK and PI3K/Akt pathways are prominent effectors of oncogenic Ras. These pathways negatively regulate each other, but the mechanism involved is incompletely understood. We now identify MEK1 as an essential regulator of lipid/protein phosphatase PTEN, through which it controls phosphatidylinositol-3-phosphate accumulation and AKT signaling. MEK1 ablation stabilizes AKT activation and, in vivo, causes a lupus-like autoimmune disease and myeloproliferation. Mechanistically, MEK1 is necessary for PTEN membrane recruitment as part of a ternary complex containing the multidomain adaptor MAGI1. Complex formation is independent of MEK1 kinase activity but requires phosphorylation of T292 on MEK1 by activated ERK. Thus, inhibiting the ERK pathway reduces PTEN membrane recruitment, increasing phosphatidylinositol-3-phosphate accumulation and AKT activation. Our data offer a conceptual framework for the observation that activation of the PI3K pathway frequently mediate resistance to MEK inhibitors and for the promising results obtained by combined MEK/PI3K inhibition in preclinical cancer models.
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Affiliation(s)
- Katarina Zmajkovicova
- Department of Microbiology and Immunobiology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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28
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Zeng L, Ehrenreiter K, Menon J, Menard R, Kern F, Nakazawa Y, Bevilacqua E, Imamoto A, Baccarini M, Rosner MR. RKIP regulates MAP kinase signaling in cells with defective B-Raf activity. Cell Signal 2013; 25:1156-65. [PMID: 23416466 DOI: 10.1016/j.cellsig.2013.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 02/08/2013] [Indexed: 01/05/2023]
Abstract
MAP kinase (MAPK) signaling results from activation of Raf kinases in response to external or internal stimuli. Here, we demonstrate that Raf kinase inhibitory protein (RKIP) regulates the activation of MAPK when B-Raf signaling is defective. We used multiple models including mouse embryonic fibroblasts (MEFs) and primary keratinocytes from RKIP- or Raf-deficient mice as well as allografts in mice to investigate the mechanism. Loss of B-Raf protein or activity significantly reduces MAPK activation in these cells. We show that RKIP depletion can rescue the compromised ERK activation and promote proliferation, and this rescue occurs through a Raf-1 dependent mechanism. These results provide formal evidence that RKIP is a bona fide regulator of Raf-1. We propose a new model in which RKIP plays a key role in regulating the ability of cells to signal through Raf-1 to ERK in B-Raf compromised cells.
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Affiliation(s)
- Lingchun Zeng
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL 60637, USA
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29
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Valluet A, Druillennec S, Barbotin C, Dorard C, Monsoro-Burq AH, Larcher M, Pouponnot C, Baccarini M, Larue L, Eychène A. B-Raf and C-Raf are required for melanocyte stem cell self-maintenance. Cell Rep 2012; 2:774-80. [PMID: 23022482 DOI: 10.1016/j.celrep.2012.08.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 06/08/2012] [Accepted: 08/22/2012] [Indexed: 11/18/2022] Open
Abstract
B-Raf and C-Raf kinases have emerged as critical players in melanoma. However, little is known about their role during development and homeostasis of the melanocyte lineage. Here, we report that knockout of B-raf and C-raf genes in this lineage results in normal pigmentation at birth with no defect in migration, proliferation, or differentiation of melanoblasts in mouse hair follicles. In contrast, the double raf knockout mice displayed hair graying resulting from a defect in cell-cycle entry of melanocyte stem cells (MSCs) and their subsequent depletion in the hair follicle bulge. Therefore, Raf signaling is dispensable for early melanocyte lineage development, but necessary for MSC maintenance.
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Affiliation(s)
- Agathe Valluet
- Institut Curie, Centre Universitaire, Orsay F-91405, France
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30
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Bliss SP, Navratil AM, Xie J, Miller A, Baccarini M, Roberson MS. ERK signaling, but not c-Raf, is required for gonadotropin-releasing hormone (GnRH)-induced regulation of Nur77 in pituitary gonadotropes. Endocrinology 2012; 153:700-11. [PMID: 22186412 PMCID: PMC3275385 DOI: 10.1210/en.2011-0247] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Stimulation of pituitary gonadotropes by hypothalamic GnRH leads to the rapid expression of several immediate early genes that play key roles in orchestrating the response of the gonadotrope to hypothalamic stimuli. Elucidation of the signaling mechanisms that couple the GnRH receptor to this immediate early gene repertoire is critical for understanding the molecular basis of GnRH action. Here we identify signaling mechanisms that underlie regulation of the orphan nuclear receptor Nur77 as a GnRH-responsive immediate early gene in αT3-1 cells and mouse gonadotropes in culture. Using a variety of approaches, we show that GnRH-induced transcriptional upregulation of Nur77 in αT3-1 cells is dependent on calcium, protein kinase C (PKC), and ERK signaling. Transcriptional activity of Nur77 within the gonadotrope is regulated posttranslationally by GnRH signaling via PKC but not ERK activity. Surprisingly, neither activation of the ERK pathway nor the transcriptional response of Nur77 to GnRH requires the activity of c-Raf kinase. In corroboration of these results, Nur77 responsiveness to GnRH was maintained in gonadotropes from mice with pituitary-targeted ablation of c-Raf kinase. In contrast, gonadotropes from mice with pituitary deficiency of ERK signaling failed to up-regulate Nur77 after GnRH stimulation. These results further clarify the role of ERK and PKC signaling in regulation of the GnRH-induced immediate early gene program as well as GnRH-induced transcription-stimulating activity of Nur77 in the gonadotrope and shed new light on the complex functional organization of this signaling pathway in the pituitary gonadotrope.
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Affiliation(s)
- Stuart P Bliss
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
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31
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Wimmer R, Cseh B, Maier B, Scherrer K, Baccarini M. Angiogenic sprouting requires the fine tuning of endothelial cell cohesion by the Raf-1/Rok-α complex. Dev Cell 2011; 22:158-71. [PMID: 22209329 PMCID: PMC3268451 DOI: 10.1016/j.devcel.2011.11.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 11/09/2011] [Accepted: 11/28/2011] [Indexed: 11/30/2022]
Abstract
Sprouting angiogenesis, crucial for the development of new blood vessels, is a prime example of collective migration in which endothelial cells migrate as a group joined via cadherin-containing adherens junctions (AJ). The actomyosin apparatus is connected to AJ and generates contractile forces, which, depending on their strength and duration, increase or decrease cell cohesion. Thus, appropriate spatiotemporal control of junctional myosin is critical, but the mechanisms underlying it are incompletely understood. We show that Raf-1 is an essential component of this regulatory network and that its ablation impairs endothelial cell cohesion, sprouting, and tumor-induced angiogenesis. Mechanistically, Raf-1 is recruited to VE-cadherin complexes by a mechanism involving the small G protein Rap1 and is required to bring the Rho effector Rok-α to nascent AJs. This Raf-1-mediated fine tuning of Rok-α signaling allows the activation of junctional myosin and the timely maturation of AJ essential for maintaining cell cohesion during sprouting angiogenesis.
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Affiliation(s)
- Reiner Wimmer
- Department of Microbiology and Immunobiology, University of Vienna, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Botond Cseh
- Department of Microbiology and Immunobiology, University of Vienna, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Barbara Maier
- Department of Microbiology and Immunobiology, University of Vienna, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Karina Scherrer
- Department of Microbiology and Immunobiology, University of Vienna, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Manuela Baccarini
- Department of Microbiology and Immunobiology, University of Vienna, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
- Corresponding author
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32
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Schikora A, Virlogeux-Payant I, Bueso E, Garcia AV, Nilau T, Charrier A, Pelletier S, Menanteau P, Baccarini M, Velge P, Hirt H. Conservation of Salmonella infection mechanisms in plants and animals. PLoS One 2011; 6:e24112. [PMID: 21915285 PMCID: PMC3167816 DOI: 10.1371/journal.pone.0024112] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 07/31/2011] [Indexed: 11/19/2022] Open
Abstract
Salmonella virulence in animals depends on effectors injected by Type III Secretion Systems (T3SSs). In this report we demonstrate that Salmonella mutants that are unable to deliver effectors are also compromised in infection of Arabidopsis thaliana plants. Transcriptome analysis revealed that in contrast to wild type bacteria, T3SS mutants of Salmonella are compromised in suppressing highly conserved Arabidopsis genes that play a prominent role during Salmonella infection of animals. We also found that Salmonella originating from infected plants are equally virulent for human cells and mice. These results indicate a high degree of conservation in the defense and infection mechanism of animal and plant hosts during Salmonella infection.
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Affiliation(s)
- Adam Schikora
- URGV Plant Genomics, INRA/University of Evry, Evry, France.
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33
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Alejandro EU, Lim GE, Mehran AE, Hu X, Taghizadeh F, Pelipeychenko D, Baccarini M, Johnson JD. Pancreatic β-cell Raf-1 is required for glucose tolerance, insulin secretion, and insulin 2 transcription. FASEB J 2011; 25:3884-95. [PMID: 21817126 DOI: 10.1096/fj.10-180349] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Regulation of glucose homeostasis by insulin depends on pancreatic β-cell growth, survival, and function. Raf-1 kinase is a major downstream target of several growth factors that promote proliferation and survival of many cell types, including the pancreatic β cells. We have previously reported that insulin protects β cells from apoptosis and promotes proliferation by activating Raf-1 signaling in cultured human islets, mouse islets, and MIN6 cells. As Raf-1 activity is critical for basal apoptosis and insulin secretion in vitro, we hypothesized that Raf-1 may play an important role in glucose homeostasis in vivo. To test this hypothesis, we utilized the Cre-loxP recombination system to obtain a pancreatic β-cell-specific ablation of Raf-1 kinase gene (RIPCre(+/+):Raf-1(flox/flox)) and a complete set of littermate controls (RIPCre(+/+):Raf-1(wt/wt)). RIPCre(+/+):Raf-1(flox/flox) mice were viable, and no effects on weight gain were observed. RIPCre(+/+):Raf-1(flox/flox) mice had increased fasting blood glucose levels and impaired glucose tolerance but normal insulin tolerance compared to littermate controls. Insulin secretion in vivo and in isolated islets was markedly impaired, but there was no apparent effect on the exocytosis machinery. However, islet insulin protein and insulin 2 mRNA, but not insulin 1 mRNA, were dramatically reduced in Raf-1-knockout mice. Analysis of insulin 2 knockout mice demonstrated that this reduction in mRNA was sufficient to impair in vivo insulin secretion. Our data further indicate that Raf-1 specifically and acutely regulates insulin 2 mRNA via negative action on Foxo1, which has been shown to selectively control the insulin 2 gene. This work provides the first direct evidence that Raf-1 signaling is essential for the regulation of basal insulin transcription and the supply of releasable insulin in vivo.
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Affiliation(s)
- Emilyn U Alejandro
- Laboratory of Molecular Signalling in Diabetes, Diabetes Research Group, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
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34
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Blasco RB, Francoz S, Santamaría D, Cañamero M, Dubus P, Charron J, Baccarini M, Barbacid M. c-Raf, but not B-Raf, is essential for development of K-Ras oncogene-driven non-small cell lung carcinoma. Cancer Cell 2011; 19:652-63. [PMID: 21514245 PMCID: PMC4854330 DOI: 10.1016/j.ccr.2011.04.002] [Citation(s) in RCA: 238] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 01/27/2011] [Accepted: 04/01/2011] [Indexed: 12/30/2022]
Abstract
We have investigated the role of individual members of the Raf/Mek/Erk cascade in the onset of K-Ras oncogene-driven non-small cell lung carcinoma (NSCLC). Ablation of Erk1 or Erk2 in K-Ras oncogene-expressing lung cells had no significant effect due to compensatory activities. Yet, elimination of both Erk kinases completely blocked tumor development. Similar results were obtained with Mek kinases. Ablation of B-Raf had no significant effect on tumor development. However, c-Raf expression was absolutely essential for the onset of NSCLC. Interestingly, concomitant elimination of c-Raf and B-Raf in adult mice had no deleterious consequences for normal homeostasis. These results indicate that c-Raf plays a unique role in mediating K-Ras signaling and makes it a suitable target for therapeutic intervention.
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Affiliation(s)
- Rafael B. Blasco
- Molecular Oncology, Centro Nacional de Investigaciones Oncológicas (CNIO), E-28029 Madrid, Spain
| | - Sarah Francoz
- Molecular Oncology, Centro Nacional de Investigaciones Oncológicas (CNIO), E-28029 Madrid, Spain
| | - David Santamaría
- Molecular Oncology, Centro Nacional de Investigaciones Oncológicas (CNIO), E-28029 Madrid, Spain
| | - Marta Cañamero
- Biotechnology Programmes, Centro Nacional de Investigaciones Oncológicas (CNIO), E-28029 Madrid, Spain
| | - Pierre Dubus
- Université de Bordeaux, EA2406, F-33076 Bordeaux, France
| | - Jean Charron
- Centre de Recherche en Cancérologie de l’Université Laval, CRCHUQ, Hôtel-Dieu de Québec, Québec, Canada
| | - Manuela Baccarini
- Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, Vienna, 1030 Austria.
| | - Mariano Barbacid
- Molecular Oncology, Centro Nacional de Investigaciones Oncológicas (CNIO), E-28029 Madrid, Spain
- Address correspondence to M.B. ()
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35
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Abstract
The Ras/Raf/MEK/ERK (extracellular signal-regulated kinase) pathway is primarily responsible for mitogenesis in metazoans, and mutational activation of this pathway is common in cancer. A variety of selective chemical inhibitors directed against the mitogen-activated protein kinase pathway are now available for clinical investigation and thus the determination of the importance of each of the kinases in oncogenesis is paramount. We investigated the role of two Raf kinases, B-Raf and C-Raf, in Ras oncogenesis, and found that although B-Raf and C-Raf have overlapping functions in primary mesenchymal cells, C-Raf but not B-Raf is required for the proliferative effects of K-Ras(G12D) in primary epithelial cells. Furthermore, in a lung cancer mouse model, C-Raf is essential for tumor initiation by oncogenic K-Ras(G12D), whereas B-Raf is dispensable for this process. Our findings reveal that K-Ras(G12D) elicits its oncogenic effects primarily through C-Raf and suggest that selective C-Raf inhibition could be explored as a therapeutic strategy for K-Ras-dependent cancers.
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Affiliation(s)
- Florian A Karreth
- Li Ka Shing Centre, Cambridge Research Institute, Cancer Research UK, Cambridge, United Kingdom
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36
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37
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Schikora A, Virlogeux-Payant I, Bueso E, Garcia AV, Nilau T, Charrier A, Pelletier S, Menanteau P, Baccarini M, Velge P, Hirt H. Conservation of Salmonella infection mechanisms in plants and animals. PLoS One 2011. [PMID: 21915285 DOI: 10.1371/journal.pone.0024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
Salmonella virulence in animals depends on effectors injected by Type III Secretion Systems (T3SSs). In this report we demonstrate that Salmonella mutants that are unable to deliver effectors are also compromised in infection of Arabidopsis thaliana plants. Transcriptome analysis revealed that in contrast to wild type bacteria, T3SS mutants of Salmonella are compromised in suppressing highly conserved Arabidopsis genes that play a prominent role during Salmonella infection of animals. We also found that Salmonella originating from infected plants are equally virulent for human cells and mice. These results indicate a high degree of conservation in the defense and infection mechanism of animal and plant hosts during Salmonella infection.
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Affiliation(s)
- Adam Schikora
- URGV Plant Genomics, INRA/University of Evry, Evry, France.
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38
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Wimmer R, Baccarini M. Partner exchange: protein-protein interactions in the Raf pathway. Trends Biochem Sci 2010; 35:660-8. [PMID: 20621483 DOI: 10.1016/j.tibs.2010.06.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 05/27/2010] [Accepted: 06/07/2010] [Indexed: 01/07/2023]
Abstract
The three-tiered Raf-MEK-ERK kinase module is activated downstream of Ras and has been traditionally linked to cellular proliferation. Mammals have three Raf, two Mek and two Erk genes. Recently, the analysis of protein-protein interactions in the pathway has begun to provide a rationale for the redundancy within each tier. New results show that the MEK-ERK-activating unit consists of Raf hetero- and homodimers; downstream of Raf, MEK1-MEK2 heterodimers and ERK dimers are required for temporal and spatial pathway regulation. Finally, C-Raf mediates pathway crosstalk downstream of Ras by directly binding to and inhibiting kinases engaged in other signaling cascades. Given the roles of these interactions in tumorigenesis, their study will provide new opportunities for molecule-based therapies that target the pathway.
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Affiliation(s)
- Reiner Wimmer
- University of Vienna, Center for Molecular Biology, Max F. Perutz Laboratories, Doktor-Bohr-Gasse 9, A-1030 Vienna, Austria
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39
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Francoz S, Blasco R, Cañamero M, Dubus P, Baccarini M, Barbacid M. R19 – Oral C-Raf, acteur clé dans la signalisation de l’oncogène K-Ras dans le carcinome pulmonaire non à petites cellules. Bull Cancer 2010. [DOI: 10.1016/s0007-4551(15)30936-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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40
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De Andrea M, Rittà M, Landini MM, Borgogna C, Mondini M, Kern F, Ehrenreiter K, Baccarini M, Marcuzzi GP, Smola S, Pfister H, Landolfo S, Gariglio M. Keratinocyte-specific stat3 heterozygosity impairs development of skin tumors in human papillomavirus 8 transgenic mice. Cancer Res 2010; 70:7938-48. [PMID: 20876801 DOI: 10.1158/0008-5472.can-10-1128] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human papillomaviruses (HPV) of the genus β are thought to play a role in human skin cancers, but this has been difficult to establish using epidemiologic approaches. To gain insight into the transforming activities of β-HPV, transgenic mouse models have been generated that develop skin tumors. Recent evidence suggests a central role of signal transducer and activator of transcription 3 (Stat3) as a transcriptional node for cancer cell-autonomous initiation of a tumor-promoting gene signature associated with cell proliferation, cell survival, and angiogenesis. Moreover, high levels of phospho-Stat3 have been detected in tumors arising in HPV8-CER transgenic mice. In this study, we investigate the in vivo role of Stat3 in HPV8-induced skin carcinogenesis by combining our established experimental model of HPV8-induced skin cancer with epidermis-restricted Stat3 ablation. Stat3 heterozygous epidermis was less prone to tumorigenesis than wild-type epidermis. Three of the 23 (13%) Stat3(+/-):HPV8 animals developed tumors within 12 weeks of life, whereas 54.3% of Stat3(+/+):HPV8 mice already exhibited tumors in the same observation period (median age for tumor appearance, 10 weeks). The few tumors that arose in the Stat3(+/-):HPV8 mice were benign and never progressed to a more malignant phenotype. Collectively, these results offer direct evidence of a critical role for Stat3 in HPV8-driven epithelial carcinogenesis. Our findings imply that targeting Stat3 activity in keratinocytes may be a viable strategy to prevent and treat HPV-induced skin cancer.
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Affiliation(s)
- Marco De Andrea
- Department of Public Health and Microbiology, Medical School of Turin, Turin, Italy
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41
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Niault T, Sobczak I, Meissl K, Weitsman G, Piazzolla D, Maurer G, Kern F, Ehrenreiter K, Hamerl M, Moarefi I, Leung T, Carugo O, Ng T, Baccarini M. From autoinhibition to inhibition in trans: the Raf-1 regulatory domain inhibits Rok-alpha kinase activity. ACTA ACUST UNITED AC 2010; 187:335-42. [PMID: 19948477 PMCID: PMC2779248 DOI: 10.1083/jcb.200906178] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The mechanism by which Raf-1 antagonizes Rok-α to promote migration and tumorigenesis is revealed. The activity of Raf-1 and Rok-α kinases is regulated by intramolecular binding of the regulatory region to the kinase domain. Autoinhibition is relieved upon binding to the small guanosine triphosphatases Ras and Rho. Downstream of Ras, Raf-1 promotes migration and tumorigenesis by antagonizing Rok-α, but the underlying mechanism is unknown. In this study, we show that Rok-α inhibition by Raf-1 relies on an intermolecular interaction between the Rok-α kinase domain and the cysteine-rich Raf-1 regulatory domain (Raf-1reg), which is similar to Rok-α's own autoinhibitory region. Thus, Raf-1 mediates Rok-α inhibition in trans, which is a new concept in kinase regulation. This mechanism is physiologically relevant because Raf-1reg is sufficient to rescue all Rok-α–dependent defects of Raf-1–deficient cells. Downstream of Ras and Rho, the Raf-1–Rok-α interaction represents a novel paradigm of pathway cross talk that contributes to tumorigenesis and cell motility.
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Affiliation(s)
- Théodora Niault
- Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, 1030 Vienna, Austria
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42
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Abstract
Some 25 years ago, Raf was discovered as the transforming principle shared by a murine sarcoma and an avian carcinoma virus. Thus, Raf and tumorigenesis have been connected from the very beginning. Ten years later, the work of many groups instated Raf as the link between Ras, the oncogene most frequently mutated in human cancers, and the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK/ERK) module, which with its manifold substrates can contribute to different aspects of carcinogenesis. Finally, the discovery of activating B-Raf mutations in a subset of human cancers, notably melanomas, conclusively established Raf as a major player in tumor development. Recent studies in animal models now show that endogenous C-Raf is essential for the development and maintenance of Ras-induced epidermal tumors. Surprisingly, the role of C-Raf in this case is not that of an mitogen-activated protein kinase activator, but rather that of an endogenous inhibitor of Rho signaling, expanding the range of tumor-related Raf targets. This review focuses on old and new targets of Raf in tumorigenesis.
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Affiliation(s)
- Théodora S Niault
- Center for Molecular Biology, Max F Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
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43
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Abstract
The Ras/Raf/MEK/ERK cascade is a highly conserved signal transduction module, whose activation results in a number of different physiological outcomes. Depending on the cell type or the stimulus used, the pathway has been implicated in proliferation, differentiation, apoptosis, and migration. Because of this wide range of activities, these kinases are considered attractive (anticancer) therapeutic targets. However, their essential functions in the context of the whole organism are still incompletely known. Here, we describe immunohistochemical and immunofluorescence methods that can be used to define the essential function(s) and the relevant downstream targets of Raf-1, B-Raf, and Mek-1 in in vivo models of organ development, remodeling, and neoplasia.
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Affiliation(s)
- Gergana Galabova-Kovacs
- Max F. Perutz Laboratories, Center for Molecular Biology of the University of Vienna, Vienna, Austria
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44
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Ehrenreiter K, Kern F, Velamoor V, Meissl K, Galabova-Kovacs G, Sibilia M, Baccarini M. Raf-1 addiction in Ras-induced skin carcinogenesis. Cancer Cell 2009; 16:149-60. [PMID: 19647225 DOI: 10.1016/j.ccr.2009.06.008] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 03/19/2009] [Accepted: 06/10/2009] [Indexed: 11/29/2022]
Abstract
Ras activation is common to many human cancers and promotes cell proliferation and survival by initiating multiple signaling cascades. Accordingly, Ras-transformed cells are generally considered too resourceful to become addicted to a single effector. In contrast to this tenet, we now demonstrate an absolute, cell autonomous requirement for Raf-1 in the development and maintenance of Ras-induced skin epidermis tumors. Mechanistically, Raf-1 functions as an endogenous inhibitor dimming the activity of the Rho-dependent kinase Rok-alpha in the context of a Ras-induced Raf-1:Rok-alpha complex. Raf-1-induced Rok-alpha inhibition allows the phosphorylation of STAT3 and Myc expression and promotes dedifferentiation in Ras-induced tumors. These data link the Raf-1:Rok-alpha complex to STAT3/Myc activation and delineate a pathway crucial for cell fate decision in Ras-induced tumorigenesis.
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Affiliation(s)
- Karin Ehrenreiter
- Max F. Perutz Laboratories, Department of Microbiology and Immunobiology, University of Vienna, Vienna, Austria
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45
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Edelblum KL, Washington MK, Koyama T, Robine S, Baccarini M, Polk DB. Raf protects against colitis by promoting mouse colon epithelial cell survival through NF-kappaB. Gastroenterology 2008; 135:539-51. [PMID: 18598699 PMCID: PMC2640938 DOI: 10.1053/j.gastro.2008.04.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 04/03/2008] [Accepted: 04/24/2008] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Raf-1 kinase is a key regulator of a number of cellular processes, which promote the maintenance of a healthy colon epithelium. This study addresses the role of Raf in epithelial cell survival in response to dextran sulfate sodium (DSS)-induced injury and inflammation. METHODS Inducible intestinal epithelium-specific Raf knockout mice were generated and subjected to acute colitis followed by a short recovery period. Colon sections were analyzed by in situ oligo ligation or immunostaining for Ki67, phospho-extracellular signal regulated kinase, and nuclear factor-kappaB p65. Western blot analysis and terminal deoxynucleotidyl transferase nick-end labeling assays were performed on Raf small interfering RNA-transfected young adult mouse colon cells following DSS treatment. RESULTS We report that Raf protects against epithelial injury and inflammation and promotes recovery from acute DSS-induced colitis by both MAPK/ERK kinase (MEK)-dependent and -independent pathways. Furthermore, we demonstrate that Raf induces novel cell survival responses through activating nuclear factor-kappaB in a MEK-independent manner. CONCLUSIONS These novel findings indicate a protective role for Raf in colon epithelium following ulcerative damage through inhibiting cell apoptosis and promoting proliferation with important implications for responses such as inflammation-associated carcinogenesis.
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Affiliation(s)
| | | | | | - Sylvie Robine
- UMR 144 Centre National de la Recherche Scientifique, Institut Curie, Paris, France
| | | | - D. Brent Polk
- Department of Cell & Developmental Biology, Vanderbilt University, Department of Pediatrics, Division of Gastroenterology, Hepatology & Nutrition, Vanderbilt University School of Medicine, 1025 MRBIV, Nashville, TN 37232-0696
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46
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Telci D, Wang Z, Li X, Verderio EAM, Humphries MJ, Baccarini M, Basaga H, Griffin M. Fibronectin-tissue transglutaminase matrix rescues RGD-impaired cell adhesion through syndecan-4 and beta1 integrin co-signaling. J Biol Chem 2008; 283:20937-47. [PMID: 18499669 DOI: 10.1074/jbc.m801763200] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heterotropic association of tissue transglutaminase (TG2) with extracellular matrix-associated fibronectin (FN) can restore the adhesion of fibroblasts when the integrin-mediated direct binding to FN is impaired using RGD-containing peptide. We demonstrate that the compensatory effect of the TG-FN complex in the presence of RGD-containing peptides is mediated by TG2 binding to the heparan sulfate chains of the syndecan-4 cell surface receptor. This binding mediates activation of protein kinase Calpha (PKCalpha) and its subsequent interaction with beta(1) integrin since disruption of PKCalpha binding to beta(1) integrins with a cell-permeant competitive peptide inhibits cell adhesion and the associated actin stress fiber formation. Cell signaling by this process leads to the activation of focal adhesion kinase and ERK1/2 mitogen-activated protein kinases. Fibroblasts deficient in Raf-1 do not respond fully to the TG-FN complex unless either the full-length kinase competent Raf-1 or the kinase-inactive domain of Raf-1 is reintroduced, indicating the involvement of the Raf-1 protein in the signaling mechanism. We propose a model for a novel RGD-independent cell adhesion process that could be important during tissue injury and/or remodeling whereby TG-FN binding to syndecan-4 activates PKCalpha leading to its association with beta(1) integrin, reinforcement of actin-stress fiber organization, and MAPK pathway activation.
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Affiliation(s)
- Dilek Telci
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, United Kingdom
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47
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Galabova-Kovacs G, Catalanotti F, Matzen D, Reyes GX, Zezula J, Herbst R, Silva A, Walter I, Baccarini M. Essential role of B-Raf in oligodendrocyte maturation and myelination during postnatal central nervous system development. ACTA ACUST UNITED AC 2008; 180:947-55. [PMID: 18332218 PMCID: PMC2265404 DOI: 10.1083/jcb.200709069] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations in the extracellular signal-regulated kinase (ERK) pathway, particularly in the mitogen-activated protein kinase/ERK kinase (MEK) activator B-Raf, are associated with human tumorigenesis and genetic disorders. Hence, B-Raf is a prime target for molecule-based therapies, and understanding its essential biological functions is crucial for their success. B-Raf is expressed preferentially in cells of neuronal origin. Here, we show that in mice, conditional ablation of B-Raf in neuronal precursors leads to severe dysmyelination, defective oligodendrocyte differentiation, and reduced ERK activation in brain. Both B-Raf ablation and chemical inhibition of MEK impair oligodendrocyte differentiation in vitro. In glial cell cultures, we find B-Raf in a complex with MEK, Raf-1, and kinase suppressor of Ras. In B-Raf–deficient cells, more Raf-1 is recruited to MEK, yet MEK/ERK phosphorylation is impaired. These data define B-Raf as the rate-limiting MEK/ERK activator in oligodendrocyte differentiation and myelination and have implications for the design and use of Raf inhibitors.
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48
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Matallanas D, Romano D, Yee K, Meissl K, Kucerova L, Piazzolla D, Baccarini M, Vass JK, Kolch W, O’Neill E. RASSF1A elicits apoptosis through an MST2 pathway directing proapoptotic transcription by the p73 tumor suppressor protein. Mol Cell 2007; 27:962-75. [PMID: 17889669 PMCID: PMC2821687 DOI: 10.1016/j.molcel.2007.08.008] [Citation(s) in RCA: 313] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 03/29/2007] [Accepted: 08/10/2007] [Indexed: 12/19/2022]
Abstract
RASSF1A is a tumor suppressor gene that is epigenetically silenced in a wide variety of sporadic human malignancies. Expression of alternative RASSF1 isoforms cannot substitute for RASSF1A-promoted cell-cycle arrest and apoptosis. Apoptosis can be driven by either activating Bax or by activation of MST kinases. The Raf1 proto-oncogene binds to MST2, preventing its activation and proapoptotic signaling. Here we show that key steps in RASSF1A-induced apoptosis are the disruption of the inhibitory Raf1-MST2 complex by RASSF1A and the concomitant enhancement of MST2 interaction with its substrate, LATS1. Subsequently, RASSF1A-activated LATS1 phosphorylates and releases the transcriptional regulator YAP1, allowing YAP1 to translocate to the nucleus and associate with p73, resulting in transcription of the proapoptotic target gene puma. Our results describe an MST2-dependent effector pathway for RASSF1A proapoptotic signaling and indicate that silencing of RASSF1A in tumors removes a proapoptotic signal emanating from p73.
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Affiliation(s)
- David Matallanas
- Signaling and Proteomics Laboratory The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - David Romano
- Signaling and Proteomics Laboratory The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Karen Yee
- Tumor Suppressor Laboratory The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Katrin Meissl
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
| | - Lucia Kucerova
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
| | - Daniela Piazzolla
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
| | - Manuela Baccarini
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
| | - J. Keith Vass
- Bioinformatics Group The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Walter Kolch
- Signaling and Proteomics Laboratory The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Sir Henry Wellcome Functional Genomics Facility, University of Glasgow, Glasgow G12 8QQ, UK
- Correspondence: (W.K.), (E.O.)
| | - Eric O’Neill
- Signaling and Proteomics Laboratory The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Correspondence: (W.K.), (E.O.)
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49
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Niault T, Ehrenreiter K, Baccarini M. 109 Raf Kinases Maintain Skin Homeostasis. Cytokine 2007. [DOI: 10.1016/j.cyto.2007.07.114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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50
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Zhong J, Li X, McNamee C, Chen AP, Baccarini M, Snider WD. Raf kinase signaling functions in sensory neuron differentiation and axon growth in vivo. Nat Neurosci 2007; 10:598-607. [PMID: 17396120 DOI: 10.1038/nn1898] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 03/23/2007] [Indexed: 11/09/2022]
Abstract
To define the role of the Raf serine/threonine kinases in nervous system development, we conditionally targeted B-Raf and C-Raf, two of the three known mammalian Raf homologs, using a mouse line expressing Cre recombinase driven by a nestin promoter. Targeting of B-Raf, but not C-Raf, markedly attenuated baseline phosphorylation of Erk in neural tissues and led to growth retardation. Conditional elimination of B-Raf in dorsal root ganglion (DRG) neurons did not interfere with survival, but instead caused marked reduction in expression of the glial cell line-derived neurotrophic factor receptor Ret at postnatal stages, associated with a profound reduction in levels of transcription factor CBF-beta. Elimination of both alleles of Braf, which encodes B-Raf, and one allele of Raf1, which encodes C-Raf, affected DRG neuron maturation as well as proprioceptive axon projection toward the ventral horn in the spinal cord. Finally, conditional elimination of all Braf and Raf1 alleles strongly reduced neurotrophin-dependent axon growth in vitro as well as cutaneous axon terminal arborization in vivo. We conclude that Raf function is crucial for several aspects of DRG neuron development, including differentiation and axon growth.
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Affiliation(s)
- Jian Zhong
- Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7250, USA
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