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Wang P, Laster K, Jia X, Dong Z, Liu K. Targeting CRAF kinase in anti-cancer therapy: progress and opportunities. Mol Cancer 2023; 22:208. [PMID: 38111008 PMCID: PMC10726672 DOI: 10.1186/s12943-023-01903-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/16/2023] [Indexed: 12/20/2023] Open
Abstract
The RAS/mitogen-activated protein kinase (MAPK) signaling cascade is commonly dysregulated in human malignancies by processes driven by RAS or RAF oncogenes. Among the members of the RAF kinase family, CRAF plays an important role in the RAS-MAPK signaling pathway, as well as in the progression of cancer. Recent research has provided evidence implicating the role of CRAF in the physiological regulation and the resistance to BRAF inhibitors through MAPK-dependent and MAPK-independent mechanisms. Nevertheless, the effectiveness of solely targeting CRAF kinase activity remains controversial. Moreover, the kinase-independent function of CRAF may be essential for lung cancers with KRAS mutations. It is imperative to develop strategies to enhance efficacy and minimize toxicity in tumors driven by RAS or RAF oncogenes. The review investigates CRAF alterations observed in cancers and unravels the distinct roles of CRAF in cancers propelled by diverse oncogenes. This review also seeks to summarize CRAF-interacting proteins and delineate CRAF's regulation across various cancer hallmarks. Additionally, we discuss recent advances in pan-RAF inhibitors and their combination with other therapeutic approaches to improve treatment outcomes and minimize adverse effects in patients with RAF/RAS-mutant tumors. By providing a comprehensive understanding of the multifaceted role of CRAF in cancers and highlighting the latest developments in RAF inhibitor therapies, we endeavor to identify synergistic targets and elucidate resistance pathways, setting the stage for more robust and safer combination strategies for cancer treatment.
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Affiliation(s)
- Penglei Wang
- Department of Pathophysiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China
- Tianjian Laboratory for Advanced Biomedical Sciences, Zhengzhou, 450052, Henan, China
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, 450000, China
| | - Kyle Laster
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, 450000, China
| | - Xuechao Jia
- Department of Pathophysiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China
- Tianjian Laboratory for Advanced Biomedical Sciences, Zhengzhou, 450052, Henan, China
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, 450000, China
| | - Zigang Dong
- Department of Pathophysiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China.
- Tianjian Laboratory for Advanced Biomedical Sciences, Zhengzhou, 450052, Henan, China.
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, 450000, China.
- Department of Pathophysiology, School of Basic Medical Sciences, China-US (Henan) Hormel Cancer Institute, AMS, College of Medicine, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, 450001, Henan, China.
| | - Kangdong Liu
- Department of Pathophysiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China.
- Tianjian Laboratory for Advanced Biomedical Sciences, Zhengzhou, 450052, Henan, China.
- China-US (Henan) Hormel Cancer Institute, Zhengzhou, 450000, China.
- Department of Pathophysiology, School of Basic Medical Sciences, China-US (Henan) Hormel Cancer Institute, AMS, College of Medicine, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, 450001, Henan, China.
- Basic Medicine Sciences Research Center, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450052, Henan, China.
- State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450000, Henan, China.
- Provincial Cooperative Innovation Center for Cancer Chemoprevention, Zhengzhou University, Zhengzhou, 450000, Henan, China.
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2
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Yap J, Deepak RNVK, Tian Z, Ng WH, Goh KC, Foo A, Tee ZH, Mohanam MP, Sim YRM, Degirmenci U, Lam P, Chen Z, Fan H, Hu J. The stability of R-spine defines RAF inhibitor resistance: A comprehensive analysis of oncogenic BRAF mutants with in-frame insertion of αC-β4 loop. SCIENCE ADVANCES 2021; 7:7/24/eabg0390. [PMID: 34108213 PMCID: PMC8189578 DOI: 10.1126/sciadv.abg0390] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
Although targeting BRAF mutants with RAF inhibitors has achieved promising outcomes in cancer therapy, drug resistance remains a remarkable challenge, and underlying molecular mechanisms are not fully understood. Here, we characterized a previously unknown group of oncogenic BRAF mutants with in-frame insertions (LLRins506 or VLRins506) of αC-β4 loop. Using structure modeling and molecular dynamics simulation, we found that these insertions formed a large hydrophobic network that stabilizes R-spine and thus triggers the catalytic activity of BRAF. Furthermore, these insertions disrupted BRAF dimer interface and impaired dimerization. Unlike BRAF(V600E), these BRAF mutants with low dimer affinity were strongly resistant to all RAF inhibitors in clinic or clinical trials, which arises from their stabilized R-spines. As predicted by molecular docking, the stabilized R-spines in other BRAF mutants also conferred drug resistance. Together, our data indicated that the stability of R-spine but not dimer affinity determines the RAF inhibitor resistance of oncogenic BRAF mutants.
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Affiliation(s)
- Jiajun Yap
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - R N V Krishna Deepak
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
| | - Zizi Tian
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Wan Hwa Ng
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Kah Chun Goh
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Alicia Foo
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Zi Heng Tee
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Manju Payini Mohanam
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Yuen Rong M Sim
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Ufuk Degirmenci
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
| | - Paula Lam
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, MD9, Singapore 117593, Singapore
- Cellvec Pte. Ltd., 100 Pasir Panjang Road, #04-02, Singapore 118518, Singapore
| | - Zhongzhou Chen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Hao Fan
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore.
| | - Jiancheng Hu
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore.
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Crescen, Singapore 169610, Singapore
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3
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Ullah R, Yin Q, Snell AH, Wan L. RAF-MEK-ERK pathway in cancer evolution and treatment. Semin Cancer Biol 2021; 85:123-154. [PMID: 33992782 DOI: 10.1016/j.semcancer.2021.05.010] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/03/2021] [Accepted: 05/06/2021] [Indexed: 12/13/2022]
Abstract
The RAF-MEK-ERK signaling cascade is a well-characterized MAPK pathway involved in cell proliferation and survival. The three-layered MAPK signaling cascade is initiated upon RTK and RAS activation. Three RAF isoforms ARAF, BRAF and CRAF, and their downstream MEK1/2 and ERK1/2 kinases constitute a coherently orchestrated signaling module that directs a range of physiological functions. Genetic alterations in this pathway are among the most prevalent in human cancers, which consist of numerous hot-spot mutations such as BRAFV600E. Oncogenic mutations in this pathway often override otherwise tightly regulated checkpoints to open the door for uncontrolled cell growth and neoplasia. The crosstalk between the RAF-MEK-ERK axis and other signaling pathways further extends the proliferative potential of this pathway in human cancers. In this review, we summarize the molecular architecture and physiological functions of the RAF-MEK-ERK pathway with emphasis on its dysregulations in human cancers, as well as the efforts made to target the RAF-MEK-ERK module using small molecule inhibitors.
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Affiliation(s)
- Rahim Ullah
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Qing Yin
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Aidan H Snell
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA
| | - Lixin Wan
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA; Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.
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4
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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:eabc1648. [PMID: 33975980 DOI: 10.1126/scisignal.abc1648] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [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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5
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Tumor regression and resistance mechanisms upon CDK4 and RAF1 inactivation in KRAS/P53 mutant lung adenocarcinomas. Proc Natl Acad Sci U S A 2020; 117:24415-24426. [PMID: 32913049 DOI: 10.1073/pnas.2002520117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
KRAS mutant lung adenocarcinomas remain intractable for targeted therapies. Genetic interrogation of KRAS downstream effectors, including the MAPK pathway and the interphase CDKs, identified CDK4 and RAF1 as the only targets whose genetic inactivation induces therapeutic responses without causing unacceptable toxicities. Concomitant CDK4 inactivation and RAF1 ablation prevented tumor progression and induced complete regression in 25% of KRAS/p53-driven advanced lung tumors, yet a significant percentage of those tumors that underwent partial regression retained a population of CDK4/RAF1-resistant cells. Characterization of these cells revealed two independent resistance mechanisms implicating hypermethylation of several tumor suppressors and increased PI3K activity. Importantly, these CDK4/RAF1-resistant cells can be pharmacologically controlled. These studies open the door to new therapeutic strategies to treat KRAS mutant lung cancer, including resistant tumors.
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6
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Blasco MT, Navas C, Martín-Serrano G, Graña-Castro O, Lechuga CG, Martín-Díaz L, Djurec M, Li J, Morales-Cacho L, Esteban-Burgos L, Perales-Patón J, Bousquet-Mur E, Castellano E, Jacob HKC, Cabras L, Musteanu M, Drosten M, Ortega S, Mulero F, Sainz B, Dusetti N, Iovanna J, Sánchez-Bueno F, Hidalgo M, Khiabanian H, Rabadán R, Al-Shahrour F, Guerra C, Barbacid M. Complete Regression of Advanced Pancreatic Ductal Adenocarcinomas upon Combined Inhibition of EGFR and C-RAF. Cancer Cell 2019; 35:573-587.e6. [PMID: 30975481 PMCID: PMC10132447 DOI: 10.1016/j.ccell.2019.03.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 01/08/2019] [Accepted: 03/04/2019] [Indexed: 12/13/2022]
Abstract
Five-year survival for pancreatic ductal adenocarcinoma (PDAC) patients remains below 7% due to the lack of effective treatments. Here, we report that combined ablation of EGFR and c-RAF expression results in complete regression of a significant percentage of PDAC tumors driven by Kras/Trp53 mutations in genetically engineered mice. Moreover, systemic elimination of these targets induces toxicities that are well tolerated. Response to this targeted therapy correlates with transcriptional profiles that resemble those observed in human PDACs. Finally, inhibition of EGFR and c-RAF expression effectively blocked tumor progression in nine independent patient-derived xenografts carrying KRAS and TP53 mutations. These results open the door to the development of targeted therapies for PDAC patients.
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Affiliation(s)
- María Teresa Blasco
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Carolina Navas
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | | | - Osvaldo Graña-Castro
- Bioinformatics Unit, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Carmen G Lechuga
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Laura Martín-Díaz
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Magdolna Djurec
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Jing Li
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Lucia Morales-Cacho
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Laura Esteban-Burgos
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Javier Perales-Patón
- Bioinformatics Unit, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Emilie Bousquet-Mur
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Eva Castellano
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Harrys K C Jacob
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Lavinia Cabras
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Monica Musteanu
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Matthias Drosten
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Sagrario Ortega
- Transgenic Unit, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Francisca Mulero
- Molecular Imaging Unit, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Bruno Sainz
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain; Department of Biochemistry, School of Medicine, Autonomous University of Madrid, 28018 Madrid, Spain
| | - Nelson Dusetti
- Centre de Recherche en Cancérologie de Marseille (CRCM), Inserm U1068, CNRS UMR 7258, Aix-Marseille Université et Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, 163, Avenue de Luminy, 13288 Marseille, France
| | - Juan Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), Inserm U1068, CNRS UMR 7258, Aix-Marseille Université et Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, 163, Avenue de Luminy, 13288 Marseille, France
| | - Francisco Sánchez-Bueno
- Department of Surgery, Clinical University Hospital 'Virgen Arrixaca' - Murcian Institute of Biomedical Investigation (IMIB), 30120 Murcia, Spain
| | - Manuel Hidalgo
- Rosenberg Clinical Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Hossein Khiabanian
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Raul Rabadán
- Department of Systems Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Fátima Al-Shahrour
- Bioinformatics Unit, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Carmen Guerra
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain.
| | - Mariano Barbacid
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain.
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7
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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:eaar6795. [PMID: 30377225 DOI: 10.1126/scisignal.aar6795] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [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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8
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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] [Abstract] [MESH Headings] [Grants] [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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9
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Sanclemente M, Francoz S, Esteban-Burgos L, Bousquet-Mur E, Djurec M, Lopez-Casas PP, Hidalgo M, Guerra C, Drosten M, Musteanu M, Barbacid M. c-RAF Ablation Induces Regression of Advanced Kras/Trp53 Mutant Lung Adenocarcinomas by a Mechanism Independent of MAPK Signaling. Cancer Cell 2018; 33:217-228.e4. [PMID: 29395869 DOI: 10.1016/j.ccell.2017.12.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 10/24/2017] [Accepted: 12/21/2017] [Indexed: 02/07/2023]
Abstract
A quarter of all solid tumors harbor KRAS oncogenes. Yet, no selective drugs have been approved to treat these malignancies. Genetic interrogation of the MAPK pathway revealed that systemic ablation of MEK or ERK kinases in adult mice prevent tumor development but are unacceptably toxic. Here, we demonstrate that ablation of c-RAF expression in advanced tumors driven by KrasG12V/Trp53 mutations leads to significant tumor regression with no detectable appearance of resistance mechanisms. Tumor regression results from massive apoptosis. Importantly, systemic abrogation of c-RAF expression does not inhibit canonical MAPK signaling, hence, resulting in limited toxicities. These results are of significant relevance for the design of therapeutic strategies to treat K-RAS mutant cancers.
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Affiliation(s)
- Manuel Sanclemente
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Sarah Francoz
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Laura Esteban-Burgos
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Emilie Bousquet-Mur
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Magdolna Djurec
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Pedro P Lopez-Casas
- Clinical Research Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Manuel Hidalgo
- Clinical Research Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Carmen Guerra
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Matthias Drosten
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain
| | - Monica Musteanu
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain.
| | - Mariano Barbacid
- Molecular Oncology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid 28029, Spain.
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10
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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] [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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11
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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 PMCID: PMC5336153 DOI: 10.1074/jbc.m116.763342] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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12
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A cell-autonomous tumour suppressor role of RAF1 in hepatocarcinogenesis. Nat Commun 2016; 7:13781. [PMID: 28000790 PMCID: PMC5187498 DOI: 10.1038/ncomms13781] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/28/2016] [Indexed: 02/06/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is a leading cause of cancer deaths, but its molecular heterogeneity hampers the design of targeted therapies. Currently, the only therapeutic option for advanced HCC is Sorafenib, an inhibitor whose targets include RAF. Unexpectedly, RAF1 expression is reduced in human HCC samples. Modelling RAF1 downregulation by RNAi increases the proliferation of human HCC lines in xenografts and in culture; furthermore, RAF1 ablation promotes chemical hepatocarcinogenesis and the proliferation of cultured (pre)malignant mouse hepatocytes. The phenotypes depend on increased YAP1 expression and STAT3 activation, observed in cultured RAF1-deficient cells, in HCC xenografts, and in autochthonous liver tumours. Thus RAF1, although essential for the development of skin and lung tumours, is a negative regulator of hepatocarcinogenesis. This unexpected finding highlights the contribution of the cellular/tissue environment in determining the function of a protein, and underscores the importance of understanding the molecular context of a disease to inform therapy design.
The kinase RAF1 usually exerts pro-tumorigenic functions promoting proliferation in RAS-driven cancers. Here, the authors using a mouse model of HCC and clinical data describe an unexpected oncosuppressor role of RAF1 in hepatocarcinoma development linked to a gp130-dependent Stat3 activation and YAP1 regulation.
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13
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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] [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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14
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Lai XH, Xu Y, Chen XM, Ren Y. Macrophage cell death upon intracellular bacterial infection. ACTA ACUST UNITED AC 2015; 2:e779. [PMID: 26690967 DOI: 10.14800/macrophage.779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Macrophage-pathogen interaction is a complex process and the outcome of this tag-of-war for both sides is to live or die. Without attempting to be comprehensive, this review will discuss the complexity and significance of the interaction outcomes between macrophages and some facultative intracellular bacterial pathogens as exemplified by Francisella, Salmonella, Shigella and Yersinia. Upon bacterial infection, macrophages can die by a variety of ways, such as apoptosis, autophagic cell death, necrosis, necroptosis, oncosis, pyronecrosis, pyroptosis etc, which is the focus of this review.
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Affiliation(s)
- Xin-He Lai
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Institute of Translational Medicine, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yunsheng Xu
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Institute of Translational Medicine, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Department of Dermato-venerology, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiao-Ming Chen
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Institute of Translational Medicine, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Department of Pediatric Surgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yi Ren
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA)
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15
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An S, Yang Y, Ward R, Liu Y, Guo XX, Xu TR. Raf-interactome in tuning the complexity and diversity of Raf function. FEBS J 2014; 282:32-53. [PMID: 25333451 DOI: 10.1111/febs.13113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/06/2014] [Accepted: 10/14/2014] [Indexed: 12/23/2022]
Abstract
Raf kinases have been intensely studied subsequent to their discovery 30 years ago. The Ras-Raf-mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-extracellular signal-regulated kinase/mitogen-activated protein kinase (Ras-Raf-MEK-ERK/MAPK) signaling pathway is at the heart of the signaling networks that control many fundamental cellular processes and Raf kinases takes centre stage in the MAPK pathway, which is now appreciated to be one of the most common sources of the oncogenic mutations in cancer. The dependency of tumors on this pathway has been clearly demonstrated by targeting its key nodes; however, blockade of the central components of the MAPK pathway may have some unexpected side effects. Over recent years, the Raf-interactome or Raf-interacting proteins have emerged as promising targets for protein-directed cancer therapy. This review focuses on the diversity of Raf-interacting proteins and discusses the mechanisms by which these proteins regulate Raf function, as well as the implications of targeting Raf-interacting proteins in the treatment of human cancer.
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Affiliation(s)
- Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Yunnan, China
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16
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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: 274] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [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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17
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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: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [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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18
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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] [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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19
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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] [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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20
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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: 247] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [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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21
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Karreth FA, Frese KK, DeNicola GM, Baccarini M, Tuveson DA. C-Raf is required for the initiation of lung cancer by K-Ras(G12D). Cancer Discov 2011; 1:128-36. [PMID: 22043453 DOI: 10.1158/2159-8290.cd-10-0044] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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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22
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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] [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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23
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Edelblum KL, Goettel JA, Koyama T, McElroy SJ, Yan F, Polk DB. TNFR1 promotes tumor necrosis factor-mediated mouse colon epithelial cell survival through RAF activation of NF-kappaB. J Biol Chem 2008; 283:29485-94. [PMID: 18713739 PMCID: PMC2570867 DOI: 10.1074/jbc.m801269200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Tumor necrosis factor (TNF) is a therapeutic target in the treatment of inflammatory bowel disease; however, the exact role of TNF signaling in the colon epithelium remains unclear. We demonstrate that TNF activation of TNF receptor (R)1 stimulates both pro- and anti-apoptotic signaling pathways in the colon epithelium; however, TNFR1 protects against colon epithelial cell apoptosis following TNF exposure. To investigate anti-apoptotic signaling pathways downstream of TNFR1, we generated an intestinal epithelium-specific Raf knock-out mouse and identified Raf kinase as a key regulator of colon epithelial cell survival in response to TNF. Surprisingly, Raf promotes NF-kappaB p65 phosphorylation, independent of MEK signaling, to support cell survival. Taken together, these data demonstrate a novel pathway in which Raf promotes colon epithelial cell survival through NF-kappaB downstream of TNFR1 activation. Thus, further understanding of colon epithelial cell-specific TNFR signaling may result in the identification of new targets for inflammatory bowel disease treatment and define novel mediators of colitis-associated cancer.
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Affiliation(s)
- Karen L Edelblum
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0696, USA
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24
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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: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [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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25
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Zwaferink H, Stockinger S, Hazemi P, Lemmens-Gruber R, Decker T. IFN-beta increases listeriolysin O-induced membrane permeabilization and death of macrophages. THE JOURNAL OF IMMUNOLOGY 2008; 180:4116-23. [PMID: 18322222 DOI: 10.4049/jimmunol.180.6.4116] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Type I IFN (IFN-I) signaling is detrimental to cells and mice infected with Listeria monocytogenes. In this study, we investigate the impact of IFN-I on the activity of listeriolysin O (LLO), a pore-forming toxin and virulence protein released by L. monocytogenes. Treatment of macrophages with IFN-beta increased the ability of sublytic LLO concentrations to cause transient permeability of the plasma membrane. At higher LLO concentrations, IFN-beta enhanced the complete breakdown of membrane integrity and cell death. This activity of IFN-beta required Stat1. Perturbation of the plasma membrane by LLO resulted in activation of the p38MAPK pathway. IFN-beta pretreatment enhanced LLO-mediated signaling through this pathway, consistent with its ability to increase membrane damage. p38MAPK activation in response to LLO was independent of TLR4, a putative LLO receptor, and inhibition of p38MAPK neither enhanced nor prevented LLO-induced death. IFN-beta caused cells to express increased amounts of caspase 1 and to produce a detectable caspase 1 cleavage product after LLO treatment. Contrasting recent reports with another pore-forming toxin, this pathway did not aid cell survival as caspase 1-deficient cells were equally sensitive to lysis by LLO. Key lipogenesis enzymes were suppressed in IFN-beta-treated cells, which may exacerbate the membrane damage caused by LLO.
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Affiliation(s)
- Heather Zwaferink
- Max F. Perutz Laboratories, Vienna Biocenter, Department of Microbiology and Immunobiology, University of Vienna, Vienna, Austria
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26
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Anthrax lethal toxin and Salmonella elicit the common cell death pathway of caspase-1-dependent pyroptosis via distinct mechanisms. Proc Natl Acad Sci U S A 2008; 105:4312-7. [PMID: 18337499 DOI: 10.1073/pnas.0707370105] [Citation(s) in RCA: 318] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Caspase-1 cleaves the inactive IL-1beta and IL-18 precursors into active inflammatory cytokines. In Salmonella-infected macrophages, caspase-1 also mediates a pathway of proinflammatory programmed cell death termed "pyroptosis." We demonstrate active caspase-1 diffusely distributed in the cytoplasm and localized in discrete foci within macrophages responding to either Salmonella infection or intoxication by Bacillus anthracis lethal toxin (LT). Both stimuli triggered caspase-1-dependent lysis in macrophages and dendritic cells. Activation of caspase-1 by LT required binding, uptake, and endosome acidification to mediate translocation of lethal factor (LF) into the host cell cytosol. Catalytically active LF cleaved cytosolic substrates and activated caspase-1 by a mechanism involving proteasome activity and potassium efflux. LT activation of caspase-1 is known to require the inflammasome adapter Nalp1. In contrast, Salmonella infection activated caspase-1 through an independent pathway requiring the inflammasome adapter Ipaf. These distinct mechanisms of caspase-1 activation converged on a common pathway of caspase-1-dependent cell death featuring DNA cleavage, cytokine activation, and, ultimately, cell lysis resulting from the formation of membrane pores between 1.1 and 2.4 nm in diameter and pathological ion fluxes that can be blocked by glycine. These findings demonstrate that distinct activation pathways elicit the conserved cell death effector mechanism of caspase-1-mediated pyroptosis and support the notion that this pathway of proinflammatory programmed cell death is broadly relevant to cell death and inflammation invoked by diverse stimuli.
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27
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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: 319] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [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
| | - Eric O’Neill
- Signaling and Proteomics Laboratory The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
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28
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Fulco TO, Lopes UG, Sarno EN, Sampaio EP, Saliba AM. The proteasome function is required for Mycobacterium leprae-induced apoptosis and cytokine secretion. Immunol Lett 2007; 110:82-5. [PMID: 17462745 DOI: 10.1016/j.imlet.2007.02.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 02/22/2007] [Accepted: 02/22/2007] [Indexed: 10/23/2022]
Abstract
Previous studies have demonstrated the importance of the ubiquitin-proteasome pathway in the immune response to bacterial pathogens. To investigate the role of this system in the context of leprosy, Mycobacterium leprae-stimulated peripheral blood mononuclear cells (PBMC) were treated with the proteasome inhibitor MG132 to assess the levels of apoptosis and cytokine secretion. The results showed that the inhibition of proteasome activity significantly reduced M. leprae-mediated cell death. In addition, MG132 treatment led to a significant decrease in M. leprae-induced TNF-alpha and IL-10 secretion. Together, these results suggest that modulations of the ubiquitin-proteasome pathway may participate in the human response to M. leprae.
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Affiliation(s)
- Tatiana O Fulco
- Leprosy Laboratory, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, RJ, Brazil
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29
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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] [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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30
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Galabova-Kovacs G, Matzen D, Piazzolla D, Meissl K, Plyushch T, Chen AP, Silva A, Baccarini M. Essential role of B-Raf in ERK activation during extraembryonic development. Proc Natl Acad Sci U S A 2006; 103:1325-30. [PMID: 16432225 PMCID: PMC1360532 DOI: 10.1073/pnas.0507399103] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The kinases of the Raf family have been intensively studied as activators of the mitogen-activated protein kinase kinase/extra-cellular signal-regulated kinase (ERK) module in regulated and deregulated proliferation. Genetic evidence that Raf is required for ERK activation in vivo has been obtained in lower organisms, which express only one Raf kinase, but was hitherto lacking in mammals, which express more than one Raf kinase. Ablation of the two best studied Raf kinases, B-Raf and Raf-1, is lethal at midgestation in mice, hampering the detailed study of the essential functions of these proteins. Here, we have combined conventional and conditional gene ablation to show that B-Raf is essential for ERK activation and for vascular development in the placenta. B-Raf-deficient placentae show complete absence of phosphorylated ERK and strongly reduced HIF-1alpha and VEGF levels, whereas all these parameters are normal in Raf-1-deficient placentae. In addition, neither ERK phosphorylation nor development are affected in B-raf-deficient embryos that are born alive obtained by epiblast-restricted gene inactivation. The data demonstrate that B-Raf plays a nonredundant role in ERK activation during extraembyronic mammalian development in vivo.
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31
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Salmonella and Enteropathogenic Escherichia coli Interactions with Host Cells: Signaling Pathways. EcoSal Plus 2006; 2. [PMID: 26443572 DOI: 10.1128/ecosalplus.8.8.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The host-pathogen interaction involves a myriad of initiations and responses from both sides. Bacterial pathogens such as enteropathogenic Escherichia coli (EPEC) and Salmonella enterica have numerous virulence factors that interact with and alter signaling components of the host cell to initiate responses that are beneficial to pathogen survival and persistence. The study of Salmonella and EPEC infection reveals intricate connections between host signal transduction, cytoskeletal architecture, membrane trafficking, and cytokine gene expression. The emerging picture includes elements of molecular mimicry by bacterial effectors and bacterial subversion of typical host events, with the result that EPEC is able to survive and persist in an extracellular milieu, while Salmonella establishes an intracellular niche and is able to spread systemically throughout the host. This review focuses on recent advances in our understanding of the signaling events stemming from the host-pathogen interactions specific to Salmonella and EPEC.
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32
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Konopleva M, Shi Y, Steelman LS, Shelton JG, Munsell M, Marini F, McQueen T, Contractor R, McCubrey JA, Andreeff M. Development of a Conditional In vivo Model to Evaluate the Efficacy of Small Molecule Inhibitors for the Treatment of Raf-Transformed Hematopoietic Cells. Cancer Res 2005; 65:9962-70. [PMID: 16267021 DOI: 10.1158/0008-5472.can-05-1068] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Conditionally active forms of the Raf proteins (Raf-1, B-Raf, and A-Raf) were created by ligating NH2-terminal truncated activated forms (Delta) to the estrogen receptor (ER) hormone-binding domain resulting in estradiol-regulated constructs (DeltaRaf:ER). These different Raf:ER oncoproteins were introduced into the murine FDC-P1 hematopoietic cell line, and cells that grew in response to the three DeltaRaf:ER oncoproteins were isolated. The ability of FDC-P1, DeltaRaf-1:ER, DeltaA-Raf:ER, and DeltaB-Raf:ER cells to form tumors in severe combined immunodeficient mice was compared. Mice injected with DeltaRaf:ER cells were implanted with beta-estradiol pellets to induce the DeltaRaf:ER oncoprotein. Cytokine-dependent parental cell lines did not form tumors. Implantation of beta-estradiol pellets into mice injected with DeltaRaf:ER cells significantly accelerated tumor onset and tumor size. The recovered DeltaRaf:ER cells displayed induction of extracellular signal-regulated kinase (ERK) in response to beta-estradiol stimulation, indicating that they had retained conditional activation of ERK even when passed through a severe combined immunodeficient mouse. The DeltaRaf:ER cells were very sensitive to induction of apoptosis by the mitogen-activated protein/ERK kinase (MEK) 1 inhibitor CI1040 whereas parental cells were much less affected, demonstrating that the MEK1 may be useful in eliminating Ras/Raf/MEK-transformed cells. Furthermore, the effects of in vivo administration of the MEK1 inhibitor were evaluated and this inhibitor was observed to suppress the tumorigenicity of the injected cells. This DeltaRaf:ER system can serve as a preclinical model to evaluate the effects of signal transduction inhibitors which target the Raf and MEK proteins.
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Affiliation(s)
- Marina Konopleva
- Department of Blood and Marrow Transplantation, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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Mercer K, Giblett S, Oakden A, Brown J, Marais R, Pritchard C. A-Raf and Raf-1 work together to influence transient ERK phosphorylation and Gl/S cell cycle progression. Oncogene 2005; 24:5207-17. [PMID: 15856007 DOI: 10.1038/sj.onc.1208707] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Raf/MEK/ERK (extracellular regulated kinase) signal transduction pathway controls the ability of cells to respond to proliferative, apoptotic, migratory and differentiation signals. We have investigated the combined contribution of A-Raf and Raf-1 isotypes to signalling through this pathway by generating mice with knockout mutations of both A-raf and raf-1 genes. Double knockout (DKO) mice have a more severe phenotype than single null mutations of either gene, dying in embryogenesis at E10.5. The DKO embryos show no changes in apoptosis, but staining for Ki67 indicates a generalized reduction in proliferation. DKO mouse embryonic fibroblasts (MEFs) exhibit a delayed ability to enter S phase of the cell cycle. This is associated with a reduction in levels of transiently induced MEK and ERK phosphorylation and reduced expression of c-Fos and cyclin Dl. Levels of sustained ERK phosphorylation are not significantly altered. Thus, Raf-1 and A-Raf have a combined role in controlling physiological transient ERK activation and in maintenance of cell cycle progression at its usual rate.
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Affiliation(s)
- Kathryn Mercer
- Department of Biochemistry, University of Leicester, Adrian Building, University Road, Leicester LEI 7RH, UK
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34
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Abstract
More than 20 years ago, Raf was discovered as a cellular oncogene transduced by transforming retroviruses. Since then, the three Raf isoforms have been intensively studied, mainly as the kinases linking Ras to the MEK/ERK signaling module. As this pathway is activated in human cancer, the Raf kinases are considered promising therapeutic targets, and we have learned a lot about their regulation, targets, and functions. Do they still hold surprises? Recent gene targeting studies indicate that they do. This review focuses on the regulation and biology of the best-studied Raf isoform, Raf-1, in the context of its kinase-independent functions.
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Affiliation(s)
- Manuela Baccarini
- Max F. Perutz Laboratories, Department of Microbiology and Immunobiology, The University of Vienna, Vienna Biocenter, Dr. Bohr Gasse 9, 1030 Vienna, Austria.
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35
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Cornelis S, Bruynooghe Y, Van Loo G, Saelens X, Vandenabeele P, Beyaert R. Apoptosis of hematopoietic cells induced by growth factor withdrawal is associated with caspase-9 mediated cleavage of Raf-1. Oncogene 2005; 24:1552-62. [PMID: 15674327 DOI: 10.1038/sj.onc.1208401] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Raf-1 serine/threonine kinase is a key protein that is implicated in the transmission of many growth and cell survival signals. In the present study we demonstrate that apoptosis of hematopoietic cells induced by IL-3-deprivation is associated with the cleavage of Raf-1, resulting in the separation of the N-terminal regulatory domain and the C-terminal kinase domain. Raf-1 cleavage specifically occurs upon triggering of the mitochondrial death pathway, and coincides with the activation of specific caspases. Moreover, Bcl-2 overexpression or treatment with the caspase inhibitor z-VAD.fmk completely prevented Raf-1 cleavage, whereas caspase inhibition by treatment of cells with Ac-DEVD.fmk or z-IETD.fmk, or CrmA overexpression had no effect. Furthermore, in vitro cleavage studies indicate that caspase-9, which is the apical protease in the mitochondrial death pathway, is able to cleave Raf-1 at position D279. Cell fractionation studies showed that the Raf-1 C-terminal fragment that is generated upon IL-3 withdrawal is localized predominantly to the mitochondria. In addition, constitutive expression of this C-terminal Raf-1 fragment fused to a mitochondrial targeting sequence in Ba/F3 pre-B cells significantly delays apoptosis induced by IL-3 withdrawal. These results suggest an important role for caspase-9 mediated cleavage of Raf-1 in the negative feedback regulation of hematopoietic cell apoptosis induced by growth factor withdrawal.
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Affiliation(s)
- Sigrid Cornelis
- Unit of Molecular Signal Transduction in Inflammation, Department for Molecular Biomedical Research, VIB-Ghent University, Technologiepark 927, B-9052 Ghent-Zwijnaarde, Belgium
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Ehrenreiter K, Piazzolla D, Velamoor V, Sobczak I, Small JV, Takeda J, Leung T, Baccarini M. Raf-1 regulates Rho signaling and cell migration. ACTA ACUST UNITED AC 2005; 168:955-64. [PMID: 15753127 PMCID: PMC2171799 DOI: 10.1083/jcb.200409162] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Raf kinases relay signals inducing proliferation, differentiation, and survival. The Raf-1 isoform has been extensively studied as the upstream kinase linking Ras activation to the MEK/ERK module. Recently, however, genetic experiments have shown that Raf-1 plays an essential role in counteracting apoptosis, and that it does so independently of its ability to activate MEK. By conditional gene ablation, we now show that Raf-1 is required for normal wound healing in vivo and for the migration of keratinocytes and fibroblasts in vitro. Raf-1-deficient cells show a symmetric, contracted appearance, characterized by cortical actin bundles and by a disordered vimentin cytoskeleton. These defects are due to the hyperactivity and incorrect localization of the Rho-effector Rok-alpha to the plasma membrane. Raf-1 physically associates with Rok-alpha in wild-type (WT) cells, and reintroduction of either WT or kinase-dead Raf-1 in knockout fibroblasts rescues their defects in shape and migration. Thus, Raf-1 plays an essential, kinase-independent function as a spatial regulator of Rho downstream signaling during migration.
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Affiliation(s)
- Karin Ehrenreiter
- Department of Microbiology and Genetics, Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, 1030 Vienna, Austria
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37
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Knodler LA, Finlay BB, Steele-Mortimer O. The Salmonella effector protein SopB protects epithelial cells from apoptosis by sustained activation of Akt. J Biol Chem 2005; 280:9058-64. [PMID: 15642738 DOI: 10.1074/jbc.m412588200] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Invasion of epithelial cells by Salmonella enterica is mediated by bacterial "effector" proteins that are delivered into the host cell by a type III secretion system. Although primarily known for their roles in actin rearrangements and membrane ruffling, translocated effectors also affect host cell processes that are not directly associated with invasion. Here, we show that SopB/SigD, an effector with phosphoinositide phosphatase activity, has anti-apoptotic activity in Salmonella-infected epithelial cells. Salmonella induced the sustained activation of Akt/protein kinase B, a pro-survival kinase, in a SopB-dependent manner. Failure to activate Akt resulted in increased levels of apoptosis after infection with a sopB deletion mutant (DeltasopB). Furthermore, cells infected with wild type bacteria, but not the DeltasopB strain, were protected from camptothecin-induced cleavage of caspase-3 and subsequent apoptosis. The anti-apoptotic activity of SopB was dependent on its phosphatase activity, because a catalytically inactive mutant was unable to protect cells from the effects of camptothecin. Finally, small interfering RNA was used to demonstrate the essential role of Akt in SopB-mediated protection against apoptosis. These results provide new insights into the mechanisms of apoptosis and highlight how bacterial effectors can intercept signaling pathways to manipulate host responses.
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Affiliation(s)
- Leigh A Knodler
- Laboratory of Intracellular Parasites, NIAID, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana 59840, USA
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38
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Abstract
The facultative intracellular pathogen Salmonella enterica triggers programmed cell death in macrophages. The close examination of this phenomenon has revealed an unusually complex picture involving diverse mechanisms that lead to different types of programmed cell death. It appears that the outcome of the interaction of salmonella with macrophages depends on the relative contribution of two type III protein secretion systems, in conjunction with the stimulation of innate immunity outputs through conserved determinants collectively known as 'pathogen-associated molecular patterns' (PAMPs). These interactions result in a breakdown of the balance between survival and pro-apoptotic cellular pathways, which eventually leads to macrophage cell death. The relative significance for the infection process of the different types of macrophage cell death triggered by salmonella remains to be established.
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Affiliation(s)
- Karsten Hueffer
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
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39
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Yamaguchi O, Watanabe T, Nishida K, Kashiwase K, Higuchi Y, Takeda T, Hikoso S, Hirotani S, Asahi M, Taniike M, Nakai A, Tsujimoto I, Matsumura Y, Miyazaki JI, Chien KR, Matsuzawa A, Sadamitsu C, Ichijo H, Baccarini M, Hori M, Otsu K. Cardiac-specific disruption of the c-raf-1 gene induces cardiac dysfunction and apoptosis. J Clin Invest 2004; 114:937-43. [PMID: 15467832 PMCID: PMC518660 DOI: 10.1172/jci20317] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Accepted: 08/03/2004] [Indexed: 01/22/2023] Open
Abstract
The Raf/MEK/extracellular signal-regulated kinase (ERK) signaling pathway regulates diverse cellular processes such as proliferation, differentiation, and apoptosis and is implicated as an important contributor to the pathogenesis of cardiac hypertrophy and heart failure. To examine the in vivo role of Raf-1 in the heart, we generated cardiac muscle-specific Raf-1-knockout (Raf CKO) mice with Cre-loxP-mediated recombination. The mice demonstrated left ventricular systolic dysfunction and heart dilatation without cardiac hypertrophy or lethality. The Raf CKO mice showed a significant increase in the number of apoptotic cardiomyocytes. The expression level and activation of MEK1/2 or ERK showed no difference, but the kinase activity of apoptosis signal-regulating kinase 1 (ASK1), JNK, or p38 increased significantly compared with that in controls. The ablation of ASK1 rescued heart dysfunction and dilatation as well as cardiac fibrosis. These results indicate that Raf-1 promotes cardiomyocyte survival through a MEK/ERK-independent mechanism.
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Affiliation(s)
- Osamu Yamaguchi
- Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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40
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Yamaguchi O, Watanabe T, Nishida K, Kashiwase K, Higuchi Y, Takeda T, Hikoso S, Hirotani S, Asahi M, Taniike M, Nakai A, Tsujimoto I, Matsumura Y, Miyazaki JI, Chien KR, Matsuzawa A, Sadamitsu C, Ichijo H, Baccarini M, Hori M, Otsu K. Cardiac-specific disruption of the c-raf-1 gene induces cardiac dysfunction and apoptosis. J Clin Invest 2004. [DOI: 10.1172/jci200420317] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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41
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Akarid K, Arnoult D, Micic-Polianski J, Sif J, Estaquier J, Ameisen JC. Leishmania major-mediated prevention of programmed cell death induction in infected macrophages is associated with the repression of mitochondrial release of cytochrome c. J Leukoc Biol 2004; 76:95-103. [PMID: 15075349 DOI: 10.1189/jlb.1001877] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Leishmania are obligate, intracellular parasites of macrophages in their vertebrate hosts, including humans, in which they cause disease. Here, we report that in vitro infection with Leishmania major protects murine bone marrow-derived macrophages against programmed cell death (PCD) induced by deprival of macrophage-colony stimulating factor and delays PCD caused by treatment with staurosporine, a broad inducer of PCD. This preventive effect was observed in macrophages from L. major-susceptible BALB/c and L. major-resistant C57BL/6 mice, indicating that repression of PCD did not depend on genetic background-specific regulation of T helper cell type 1 (Th1)/Th2 cytokine secretion. Prevention of effector caspase activation and PCD was associated with a repression of mitochondrial release of cytochrome c and did not involve the nuclear factor-kappaB pathway. The capacity of L. major to delay PCD induction in the infected macrophages may have implications for Leishmania pathogenesis by favoring the invasion of its host and the persistence of the parasite in the infected cells.
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Affiliation(s)
- Khadija Akarid
- INSERM/Université Paris 7, Faculté de Médecine Xavier Bichat, 16, Rue Henri Huchard, 75870 Paris Cedex 18, France
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42
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Forsberg M, Blomgran R, Lerm M, Särndahl E, Sebti SM, Hamilton A, Stendahl O, Zheng L. Differential effects of invasion by and phagocytosis of Salmonella typhimurium on apoptosis in human macrophages: potential role of Rho-GTPases and Akt. J Leukoc Biol 2003; 74:620-9. [PMID: 12960245 DOI: 10.1189/jlb.1202586] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In addition to direct activation of caspase-1 and induction of apoptosis by SipB, invasive Salmonella stimulates multiple signaling pathways that are key regulators of host cell survival. Nevertheless, little is known about the relative contributions of these pathways to Salmonella-mediated death of macrophages. We studied human monocytic U937 cells and found that apoptosis was induced by invading wild-type Salmonella typhimurium but not by phagocytosed, serum-opsonized, noninvasive Salmonella mutants. Pretreating U937 cells with inhibitors of tyrosine kinases or phosphatidylinositol-3 kinase (PI-3K) completely blocked phagocytosis of opsonized Salmonella mutants but did not affect invasion by wild-type Salmonella or the apoptosis caused by invasion. However, pretreatment with GGTI-298, a geranylgeranyltransferase-1 inhibitor that prevents prenylation of Cdc42 and Rac1, suppressed Salmonella-induced apoptosis by approximately 70%. Transduction of Tat fusion constructs containing dominant-negative Cdc42 or Rac1 significantly inhibited Salmonella-induced cell death, indicating that the cytotoxicity of Salmonella requires activation of Cdc42 and Rac. In contrast to phagocytosis of opsonized bacteria, invasion by S. typhimurium stimulated Cdc42 and Rac1, regardless of the activities of tyrosine- or PI-3K. Moreover, Salmonella infection activated Akt protein in a tyrosine-kinase or PI-3K-dependent manner, and a reduced expression of Akt by antisense transfection rendered the cells more sensitive to apoptosis induced by opsonized Salmonella. These results indicate that direct activation of Cdc42 and Rac1 by invasive Salmonella is a prerequisite of Salmonella-mediated death of U937 cells, whereas the simultaneous activation of Akt by tyrosine kinase and PI-3K during receptor-mediated phagocytosis protects cells from apoptosis.
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Affiliation(s)
- Maria Forsberg
- Division of Medical Microbiology, IMK, Linköping University, Sweden
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Abstract
Salmonella is an interesting example of how the selective pressure of host environments has led to the evolution of sophisticated bacterial virulence mechanisms. This microbe exploits the first-line of defence, the macrophage, as a crucial tool in the initiation of disease. After invasion of intestinal macrophages, a virulence protein secreted by Salmonella specifically induces apoptotic cell death by activating the cysteine protease caspase-1. The pro-apoptotic capability is necessary for successful pathogenesis. The study of mechanisms by which Salmonella induces programmed cell death offers new insights into how pathogens cause disease and into general mechanisms of activation of the innate immune system.
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Affiliation(s)
- Harri A Järveläinen
- Max Planck Institute for Infection Biology, Department of Cellular Microbiology, Campus Charité Mitte, Schumannstrasse 21/22, Berlin 10117, Germany
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Abstract
Infections with Salmonella serotypes are a major cause of food-borne diseases worldwide. Animal models other than the mouse have been employed for the study of nontyphoidal Salmonella infections because the murine model is not suitable for the study of Salmonella-induced diarrhea. The microbe has developed mechanisms to exploit the host cell machinery to its own purpose. Bacterial proteins delivered directly into the host cell cytosol cause cytoskeletal changes and interfere with host cell signaling pathways, which ultimately enhance disease manifestation. Recently, marked advances have been made in our understanding of the molecular interactions between Salmonella serotypes and their hosts. Here, we discuss the molecular basis of the pathogenesis of Salmonella-induced enteritis.
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Affiliation(s)
- R L Santos
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
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Kolbus A, Pilat S, Husak Z, Deiner EM, Stengl G, Beug H, Baccarini M. Raf-1 antagonizes erythroid differentiation by restraining caspase activation. J Exp Med 2002; 196:1347-53. [PMID: 12438425 PMCID: PMC2193984 DOI: 10.1084/jem.20020562] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The Raf kinases are key signal transducers activated by mitogens or oncogenes. The best studied Raf isoform, Raf-1, was identified as an inhibitor of apoptosis by conventional and conditional gene ablation in mice. c-raf-1(-)(/)(-) embryos are growth retarded and anemic, and die at midgestation with anomalies in the placenta and fetal liver. Here, we show that Raf-1-deficient primary erythroblasts cannot be expanded in culture due to their accelerated differentiation into mature erythrocytes. In addition, Raf-1 expression is down-regulated in differentiating wild-type cells, whereas overexpression of activated Raf-1 delays differentiation. As recently described for human erythroid precursors, we find that caspase activation is necessary for the differentiation of murine fetal liver erythroblasts. Differentiation-associated caspase activation is accelerated in erythroid progenitors lacking Raf-1 and delayed by overexpression of the activated kinase. These results reveal an essential function of Raf-1 in erythropoiesis and demonstrate that the ability of Raf-1 to restrict caspase activation is biologically relevant in a context distinct from apoptosis.
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Affiliation(s)
- Andrea Kolbus
- Research Institute of Molecular Pathology, Institute of Microbiology and Genetics, Vienna Biocenter, 1030 Vienna, Austria
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46
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Wu J. On the role of proteasomes in cell biology and proteasome inhibition as a novel frontier in the development of immunosuppressants. Am J Transplant 2002; 2:904-12. [PMID: 12482142 DOI: 10.1034/j.1600-6143.2002.21006.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The proteasome, a large protease complex in cells, is the major machinery for protein degradation. It was previously considered a humble garbage collector, performing housekeeping duties to remove misfolded or spent proteins. Until recently, the interests of immunologists in proteasomes were focused largely on its role in antigen processing. Its real importance in cell biology has only been revealed contemporarily due to the availability of relatively specific inhibitors. It has now become increasingly clear that many aspects of immune responses highly depend on proper proteasome activity. Recently, a proteasome inhibitor has been successfully used to prevent acute as well as ongoing heart allograft rejection in mice. Such inhibitors are also efficacious in treating several autoimmune diseases, such as arthritis, psoriasis, and probably type I diabetes, in animal models. Phase II and III clinical trials of proteasome inhibitors in treating various tumors have shown promising results, and the side-effects of these drugs are tolerable. Therefore, proteasome inhibition represents a new and promising frontier in immunosuppressant development.
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Affiliation(s)
- Jiangping Wu
- Laboratory of Transplantation Immunology, Nephrology Service of the Centre hospitalier de l'Université de Montréal, University of Montreal, Montreal, Canada.
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47
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Brummer T, Shaw PE, Reth M, Misawa Y. Inducible gene deletion reveals different roles for B-Raf and Raf-1 in B-cell antigen receptor signalling. EMBO J 2002; 21:5611-22. [PMID: 12411479 PMCID: PMC131085 DOI: 10.1093/emboj/cdf588] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Engagement of the B-cell antigen receptor (BCR) leads to activation of the Raf-MEK-ERK pathway and Raf kinases play an important role in the modulation of ERK activity. B lymphocytes express two Raf isoforms, Raf-1 and B-Raf. Using an inducible deletion system in DT40 cells, the contribution of Raf-1 and B-Raf to BCR signalling was dissected. Loss of Raf-1 has no effect on BCR-mediated ERK activation, whereas B-Raf-deficient DT40 cells display a reduced basal ERK activity as well as a shortened BCR-mediated ERK activation. The Raf-1/B-Raf double deficient DT40 cells show an almost complete block both in ERK activation and in the induction of the immediate early gene products c-Fos and Egr-1. In contrast, BCR-mediated activation of nuclear factor of activated T cells (NFAT) relies predominantly on B-Raf. Furthermore, complementation of Raf-1/B-Raf double deficient cells with various Raf mutants demonstrates a requirement for Ras-GTP binding in BCR-mediated activation of both Raf isoforms and also reveals the important role of the S259 residue for the regulation of Raf-1. Our study shows that BCR-mediated ERK activation involves a cooperation of both B-Raf and Raf-1, which are activated specifically in a temporally distinct manner.
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Affiliation(s)
| | - Peter E. Shaw
- Department of Molecular Immunology, Biology III, University of Freiburg and Max-Planck-Institute for Immunobiology, Stuebeweg 51, D-79108 Freiburg, Germany and
School of Biomedical Science and Institute of Cell Signalling, Queen’s Medical Centre, Nottingham NG7 2UH, UK Corresponding author e-mail:
| | | | - Yukiko Misawa
- Department of Molecular Immunology, Biology III, University of Freiburg and Max-Planck-Institute for Immunobiology, Stuebeweg 51, D-79108 Freiburg, Germany and
School of Biomedical Science and Institute of Cell Signalling, Queen’s Medical Centre, Nottingham NG7 2UH, UK Corresponding author e-mail:
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Affiliation(s)
- Manuela Baccarini
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr Bohr Gasse 9, 1030 Vienna, Austria.
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49
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Rosenberger CM, Finlay BB. Macrophages inhibit Salmonella typhimurium replication through MEK/ERK kinase and phagocyte NADPH oxidase activities. J Biol Chem 2002; 277:18753-62. [PMID: 11821396 DOI: 10.1074/jbc.m110649200] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Host responses during the later stages of Salmonella-macrophage interactions are critical to controlling infection but have not been well characterized. After 24 h of infection, nearly half of interferon-gamma-primed murine RAW 264.7 macrophage-like cells infected by Salmonella enterica serovar Typhimurium contained filamentous bacteria. Bacterial filamentation indicates a defect in completing replication and has been previously observed in bacteria responding to a variety of stresses. To understand whether macrophage gene expression was responsible for this effect on Salmonella Typhimurium replication, we used gene arrays to profile interferon-gamma-primed RAW 264.7 cell gene expression following infection. We observed an increase in MEK1 kinase mRNA at 8 h, an increase in MEK protein at 24 h, and measured phosphorylation of MEK's downstream target kinase, ERK1/2, throughout the 24-h infection period. Treatment of cells with MEK kinase inhibitors significantly reduced numbers of filamentous bacteria observed within macrophages after 24 h and increased the number of intracellular colony-forming units. Phagocyte NADPH oxidase inhibitors and antioxidants also significantly reduced bacterial filamentation. Either MEK kinase or phagocyte oxidase inhibitors could be added 4-8 h after infection and still significantly decrease bacterial filamentation. Oxidase activity appears to mediate bacterial filamentation in parallel to MEK kinase signaling, while inducible nitric-oxide synthase inhibitors had no significant effect on bacterial morphology. In summary, Salmonella Typhimurium infection of interferon-gamma-primed macrophages triggers a MEK kinase cascade at later infection times, and both MEK kinase and phagocyte NADPH oxidase activity impair bacterial replication. These two signaling pathways mediate a host bacteriostatic pathway and may play an important role in innate host defense against intracellular pathogens.
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Affiliation(s)
- Carrie M Rosenberger
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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50
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Hindley A, Kolch W. Extracellular signal regulated kinase (ERK)/mitogen activated protein kinase (MAPK)-independent functions of Raf kinases. J Cell Sci 2002; 115:1575-81. [PMID: 11950876 DOI: 10.1242/jcs.115.8.1575] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Raf comprises a family of three kinases, A-Raf, B-Raf and Raf-1, which are best known as key regulators of the MEK—MAPK/ERK cascade. This module is often perceived as a linear pathway in which ERK is the effector. However,recent advances have unveiled a role for Raf outside this established signalling unit. Current evidence, including gene-knockout studies in mice,suggests that there are ERK-independent functions of Raf kinases. Regulation of apoptosis is one area in which Raf may function independently of ERK,although its substrates remain to be identified. Other studies have suggested that Raf has kinase-independent functions and may act as a scaffold protein.
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Affiliation(s)
- Alison Hindley
- The Beatson Institute for Cancer Research, CRC Beatson Laboratories, Glasgow, G61 1BD, UK
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