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Maisonneuve P, Sahmi M, Bergeron-Labrecque F, Ma XI, Queguiner J, Arseneault G, Lefrançois M, Kurinov I, Fronzes R, Sicheri F, Therrien M. The CNK-HYP scaffolding complex promotes RAF activation by enhancing KSR-MEK interaction. Nat Struct Mol Biol 2024; 31:1028-1038. [PMID: 38388830 PMCID: PMC11257983 DOI: 10.1038/s41594-024-01233-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 01/29/2024] [Indexed: 02/24/2024]
Abstract
The RAS-MAPK pathway regulates cell proliferation, differentiation and survival, and its dysregulation is associated with cancer development. The pathway minimally comprises the small GTPase RAS and the kinases RAF, MEK and ERK. Activation of RAF by RAS is notoriously intricate and remains only partially understood. There are three RAF isoforms in mammals (ARAF, BRAF and CRAF) and two related pseudokinases (KSR1 and KSR2). RAS-mediated activation of RAF depends on an allosteric mechanism driven by the dimerization of its kinase domain. Recent work on human RAFs showed that MEK binding to KSR1 promotes KSR1-BRAF heterodimerization, which leads to the phosphorylation of free MEK molecules by BRAF. Similar findings were made with the single Drosophila RAF homolog. Here we show that the fly scaffold proteins CNK and HYP stabilize the KSR-MEK interaction, which in turn enhances RAF-KSR heterodimerization and RAF activation. The cryogenic electron microscopy structure of the minimal KSR-MEK-CNK-HYP complex reveals a ring-like arrangement of the CNK-HYP complex allowing CNK to simultaneously engage KSR and MEK, thus stabilizing the binary interaction. Together, these results illuminate how CNK contributes to RAF activation by stimulating the allosteric function of KSR and highlight the diversity of mechanisms impacting RAF dimerization as well as the regulatory potential of the KSR-MEK interaction.
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Affiliation(s)
- Pierre Maisonneuve
- Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, IECB, F-33600, Pessac, France.
- Center for Molecular, Cell and Systems Biology, Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada.
| | - Malha Sahmi
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Quebec, Canada
| | - Fanny Bergeron-Labrecque
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Quebec, Canada
| | - Xianjie Iris Ma
- Center for Molecular, Cell and Systems Biology, Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Juliette Queguiner
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Quebec, Canada
| | - Geneviève Arseneault
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Quebec, Canada
| | - Martin Lefrançois
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Quebec, Canada
| | - Igor Kurinov
- Department of Chemistry and Chemical Biology, Cornell University, NE-CAT, Argonne, IL, USA
| | - Rémi Fronzes
- Institut Européen de Chimie et Biologie, Université de Bordeaux-CNRS (UMR 5234), Pessac, France
| | - Frank Sicheri
- Center for Molecular, Cell and Systems Biology, Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada.
- Departments of Molecular Genetics and Biochemistry, University of Toronto, Toronto, Ontario, Canada.
| | - Marc Therrien
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Quebec, Canada.
- Département de pathologie et biologie cellulaire, Université de Montréal, Montréal, Quebec, Canada.
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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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3
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Bahar ME, Kim HJ, Kim DR. Targeting the RAS/RAF/MAPK pathway for cancer therapy: from mechanism to clinical studies. Signal Transduct Target Ther 2023; 8:455. [PMID: 38105263 PMCID: PMC10725898 DOI: 10.1038/s41392-023-01705-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 11/03/2023] [Accepted: 11/12/2023] [Indexed: 12/19/2023] Open
Abstract
Metastatic dissemination of solid tumors, a leading cause of cancer-related mortality, underscores the urgent need for enhanced insights into the molecular and cellular mechanisms underlying metastasis, chemoresistance, and the mechanistic backgrounds of individuals whose cancers are prone to migration. The most prevalent signaling cascade governed by multi-kinase inhibitors is the mitogen-activated protein kinase (MAPK) pathway, encompassing the RAS-RAF-MAPK kinase (MEK)-extracellular signal-related kinase (ERK) pathway. RAF kinase is a primary mediator of the MAPK pathway, responsible for the sequential activation of downstream targets, such as MEK and the transcription factor ERK, which control numerous cellular and physiological processes, including organism development, cell cycle control, cell proliferation and differentiation, cell survival, and death. Defects in this signaling cascade are associated with diseases such as cancer. RAF inhibitors (RAFi) combined with MEK blockers represent an FDA-approved therapeutic strategy for numerous RAF-mutant cancers, including melanoma, non-small cell lung carcinoma, and thyroid cancer. However, the development of therapy resistance by cancer cells remains an important barrier. Autophagy, an intracellular lysosome-dependent catabolic recycling process, plays a critical role in the development of RAFi resistance in cancer. Thus, targeting RAF and autophagy could be novel treatment strategies for RAF-mutant cancers. In this review, we delve deeper into the mechanistic insights surrounding RAF kinase signaling in tumorigenesis and RAFi-resistance. Furthermore, we explore and discuss the ongoing development of next-generation RAF inhibitors with enhanced therapeutic profiles. Additionally, this review sheds light on the functional interplay between RAF-targeted therapies and autophagy in cancer.
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Affiliation(s)
- Md Entaz Bahar
- Department of Biochemistry and Convergence Medical Sciences and Institute of Medical Science, Gyeongsang National University, College of Medicine, Jinju, South Korea
| | - Hyun Joon Kim
- Department of Anatomy and Convergence Medical Sciences and Institute of Medical Science, Gyeongsang National University, College of Medicine, Jinju, South Korea
| | - Deok Ryong Kim
- Department of Biochemistry and Convergence Medical Sciences and Institute of Medical Science, Gyeongsang National University, College of Medicine, Jinju, South Korea.
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4
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Serwe G, Kachaner D, Gagnon J, Plutoni C, Lajoie D, Duramé E, Sahmi M, Garrido D, Lefrançois M, Arseneault G, Saba-El-Leil MK, Meloche S, Emery G, Therrien M. CNK2 promotes cancer cell motility by mediating ARF6 activation downstream of AXL signalling. Nat Commun 2023; 14:3560. [PMID: 37322019 PMCID: PMC10272126 DOI: 10.1038/s41467-023-39281-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 05/31/2023] [Indexed: 06/17/2023] Open
Abstract
Cell motility is a critical feature of invasive tumour cells that is governed by complex signal transduction events. Particularly, the underlying mechanisms that bridge extracellular stimuli to the molecular machinery driving motility remain partially understood. Here, we show that the scaffold protein CNK2 promotes cancer cell migration by coupling the pro-metastatic receptor tyrosine kinase AXL to downstream activation of ARF6 GTPase. Mechanistically, AXL signalling induces PI3K-dependent recruitment of CNK2 to the plasma membrane. In turn, CNK2 stimulates ARF6 by associating with cytohesin ARF GEFs and with a novel adaptor protein called SAMD12. ARF6-GTP then controls motile forces by coordinating the respective activation and inhibition of RAC1 and RHOA GTPases. Significantly, genetic ablation of CNK2 or SAMD12 reduces metastasis in a mouse xenograft model. Together, this work identifies CNK2 and its partner SAMD12 as key components of a novel pro-motility pathway in cancer cells, which could be targeted in metastasis.
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Affiliation(s)
- Guillaume Serwe
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - David Kachaner
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Jessica Gagnon
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Cédric Plutoni
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Driss Lajoie
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Eloïse Duramé
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Malha Sahmi
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Damien Garrido
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Martin Lefrançois
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Geneviève Arseneault
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Marc K Saba-El-Leil
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Sylvain Meloche
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Gregory Emery
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Marc Therrien
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada.
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
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5
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Steckelings UM, Widdop RE, Sturrock ED, Lubbe L, Hussain T, Kaschina E, Unger T, Hallberg A, Carey RM, Sumners C. The Angiotensin AT 2 Receptor: From a Binding Site to a Novel Therapeutic Target. Pharmacol Rev 2022; 74:1051-1135. [PMID: 36180112 PMCID: PMC9553111 DOI: 10.1124/pharmrev.120.000281] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 05/19/2022] [Accepted: 06/27/2022] [Indexed: 11/22/2022] Open
Abstract
Discovered more than 30 years ago, the angiotensin AT2 receptor (AT2R) has evolved from a binding site with unknown function to a firmly established major effector within the protective arm of the renin-angiotensin system (RAS) and a target for new drugs in development. The AT2R represents an endogenous protective mechanism that can be manipulated in the majority of preclinical models to alleviate lung, renal, cardiovascular, metabolic, cutaneous, and neural diseases as well as cancer. This article is a comprehensive review summarizing our current knowledge of the AT2R, from its discovery to its position within the RAS and its overall functions. This is followed by an in-depth look at the characteristics of the AT2R, including its structure, intracellular signaling, homo- and heterodimerization, and expression. AT2R-selective ligands, from endogenous peptides to synthetic peptides and nonpeptide molecules that are used as research tools, are discussed. Finally, we summarize the known physiological roles of the AT2R and its abundant protective effects in multiple experimental disease models and expound on AT2R ligands that are undergoing development for clinical use. The present review highlights the controversial aspects and gaps in our knowledge of this receptor and illuminates future perspectives for AT2R research. SIGNIFICANCE STATEMENT: The angiotensin AT2 receptor (AT2R) is now regarded as a fully functional and important component of the renin-angiotensin system, with the potential of exerting protective actions in a variety of diseases. This review provides an in-depth view of the AT2R, which has progressed from being an enigma to becoming a therapeutic target.
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Affiliation(s)
- U Muscha Steckelings
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Robert E Widdop
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Edward D Sturrock
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Lizelle Lubbe
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Tahir Hussain
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Elena Kaschina
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Thomas Unger
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Anders Hallberg
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Robert M Carey
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
| | - Colin Sumners
- Institute of Molecular Medicine, Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark (U.M.S.); Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Clayton, Victoria, Australia (R.E.W.); Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Republic of South Africa (E.D.S., L.L.); Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (T.H.); Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular-Metabolic-Renal (CMR) Research Center, DZHK (German Centre for Cardiovascular Research), Berlin, Germany (E.K.); CARIM - School for Cardiovascular Diseases, Maastricht University, The Netherlands (T.U.); Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala University, Uppsala, Sweden (A.H.); Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia (R.M.C.); and Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida (C.S.)
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6
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Mo GCH, Posner C, Rodriguez EA, Sun T, Zhang J. A rationally enhanced red fluorescent protein expands the utility of FRET biosensors. Nat Commun 2020; 11:1848. [PMID: 32296061 PMCID: PMC7160135 DOI: 10.1038/s41467-020-15687-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 03/20/2020] [Indexed: 11/30/2022] Open
Abstract
Genetically encoded Förster Resonance Energy Transfer (FRET)-based biosensors are powerful tools to illuminate spatiotemporal regulation of cell signaling in living cells, but the utility of the red spectrum for biosensing was limited due to a lack of bright and stable red fluorescent proteins. Here, we rationally improve the photophysical characteristics of the coral-derived fluorescent protein TagRFP-T. We show that a new single-residue mutant, super-TagRFP (stagRFP) has nearly twice the molecular brightness of TagRFP-T and negligible photoactivation. stagRFP facilitates significant improvements on multiple green-red biosensors as a FRET acceptor and is an efficient FRET donor that supports red/far-red FRET biosensing. Capitalizing on the ability of stagRFP to couple with multiple FRET partners, we develop a novel multiplex method to examine the confluence of signaling activities from three kinases simultaneously in single living cells, providing evidence for a role of Src family kinases in regulating growth factor induced Akt and ERK activities.
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Affiliation(s)
- Gary C H Mo
- Department of Pharmacology, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Clara Posner
- Department of Pharmacology, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Erik A Rodriguez
- Department of Chemistry, The George Washington University, Washington, DC, 20052, USA
| | - Tengqian Sun
- Department of Pharmacology, University of California San Diego, La Jolla, CA, 92093, USA
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego, La Jolla, CA, 92093, USA.
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA.
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093, USA.
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7
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Fischer A, Mühlhäuser WWD, Warscheid B, Radziwill G. Membrane localization of acetylated CNK1 mediates a positive feedback on RAF/ERK signaling. SCIENCE ADVANCES 2017; 3:e1700475. [PMID: 28819643 PMCID: PMC5553820 DOI: 10.1126/sciadv.1700475] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 07/12/2017] [Indexed: 06/07/2023]
Abstract
Spatiotemporal control is a common mechanism that modulates activity and function of signal transducers in the signaling network. We identified acetylation of CNK1 (connector enhancer of kinase suppressor of Ras-1) as a late step in the activation of CNK1 signaling, accompanied with prolonged stimulation of extracellular signal-regulated kinase (ERK). We identified the acetyltransferase CREB (cyclic adenosine 3',5'-monophosphate response element-binding protein)-binding protein and the deacetylase SIRT2 (sirtuin type 2) as novel binding partners of CNK1, modulating the acetylation state of CNK1. Acetylation of CNK1 at position Lys414 located in the pleckstrin homology domain drives membrane localization of CNK1 in growth factor-stimulated cells. Inhibition of ERK signaling abolishes CNK1 acetylation. Cosmic database search identified CNK1 mutants at position Arg426 near the acetylation site in several human tumor types. These mutants show constitutive acetylation and membrane localization. CNK1 mutants substituting Arg426, the acetylation mimetic mutant CNK1-K414Q, and membrane-anchored CNK1 mutants all interact with the protein kinase CRAF and stimulate ERK-dependent cell proliferation and cell migration. In RAS-transformed cells, CNK1 is acetylated and membrane-bound and drives cell proliferation. Thus, growth factor-stimulated ERK signaling induces CNK1 acetylation, and acetylated CNK1 promotes ERK signaling, demonstrating a novel function of CNK1 as positive feedback regulator of the RAF/MEK (mitogen-activated protein kinase kinase)/ERK pathway. In addition, acetylation of CNK1 is an important step in oncogenic signaling, promoting cell proliferation and migration.
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Affiliation(s)
| | - Wignand W. D. Mühlhäuser
- Faculty of Biology, Department of Biochemistry, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- Faculty of Biology, Department of Biochemistry, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Gerald Radziwill
- Faculty of Biology, Department of Biochemistry, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
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8
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Abstract
Cells respond to changes in their environment, to developmental cues, and to pathogen aggression through the action of a complex network of proteins. These networks can be decomposed into a multitude of signaling pathways that relay signals from the microenvironment to the cellular components involved in eliciting a specific response. Perturbations in these signaling processes are at the root of multiple pathologies, the most notable of these being cancer. The study of receptor tyrosine kinase (RTK) signaling led to the first description of a mechanism whereby an extracellular signal is transmitted to the nucleus to induce a transcriptional response. Genetic studies conducted in drosophila and nematodes have provided key elements to this puzzle. Here, we briefly discuss the somewhat lesser known contribution of these multicellular organisms to our understanding of what has come to be known as the prototype of signaling pathways. We also discuss the ostensibly much larger network of regulators that has emerged from recent functional genomic investigations of RTK/RAS/ERK signaling.
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Affiliation(s)
- Dariel Ashton-Beaucage
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, Canada, H3C 3J7
| | - Marc Therrien
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, Canada, H3C 3J7.
- Département de Pathologie et de Biologie Cellulaire, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, Canada, H3C 3J7.
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9
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Optogenetic clustering of CNK1 reveals mechanistic insights in RAF and AKT signalling controlling cell fate decisions. Sci Rep 2016; 6:38155. [PMID: 27901111 PMCID: PMC5128868 DOI: 10.1038/srep38155] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/04/2016] [Indexed: 12/27/2022] Open
Abstract
Scaffold proteins such as the multidomain protein CNK1 orchestrate the signalling network by integrating and controlling the underlying pathways. Using an optogenetic approach to stimulate CNK1 uncoupled from upstream effectors, we identified selective clusters of CNK1 that either stimulate RAF-MEK-ERK or AKT signalling depending on the light intensity applied. OptoCNK1 implemented in MCF7 cells induces differentiation at low light intensity stimulating ERK activity whereas stimulation of AKT signalling by higher light intensity promotes cell proliferation. CNK1 clustering in response to increasing EGF concentrations revealed that CNK1 binds to RAF correlating with ERK activation at low EGF dose. At higher EGF dose active AKT binds to CNK1 and phosphorylates and inhibits RAF. Knockdown of CNK1 protects CNK1 from this AKT/RAF crosstalk. In C2 skeletal muscle cells CNK1 expression is induced with the onset of differentiation. Hence, AKT-bound CNK1 counteracts ERK stimulation in differentiated but not in proliferating cells. Ectopically expressed CNK1 facilitates C2 cell differentiation and knockdown of CNK1 impaired the transcriptional network underlying C2 cell differentiation. Thus, CNK1 expression, CNK1 clustering and the thereto related differential signalling processes decide on proliferation and differentiation in a cell type- and cell stage-dependent manner by orchestrating AKT and RAF signalling.
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10
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Fischer A, Weber W, Warscheid B, Radziwill G. AKT-dependent phosphorylation of the SAM domain induces oligomerization and activation of the scaffold protein CNK1. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:89-100. [PMID: 27769899 DOI: 10.1016/j.bbamcr.2016.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 10/06/2016] [Accepted: 10/15/2016] [Indexed: 12/27/2022]
Abstract
Scaffold proteins are hubs for the coordination of intracellular signaling networks. The scaffold protein CNK1 promotes several signal transduction pathway. Here we demonstrate that sterile motif alpha (SAM) domain-dependent oligomerization of CNK1 stimulates CNK1-mediated signaling in growth factor-stimulated cells. We identified Ser22 located within the SAM domain as AKT-dependent phosphorylation site triggering CNK1 oligomerization. Oligomeric CNK1 increased the affinity for active AKT indicating a positive AKT feedback mechanism. A CNK1 mutant lacking the SAM domain and the phosphorylation-defective mutant CNK1S22A antagonizes oligomerization and prevents CNK1-driven cell proliferation and matrix metalloproteinase 14 promoter activation. The phosphomimetic mutant CNK1S22D constitutively oligomerizes and stimulates CNK1 downstream signaling. Searching the COSMIC database revealed Ser22 as putative target for oncogenic activation of CNK1. Like the phosphomimetic mutant CNK1S22D, the oncogenic mutant CNK1S22F forms clusters in serum-starved cells comparable to clusters of CNK1 in growth factor-stimulated cells. CNK1 clusters induced by activating Ser22 mutants correlate with enhanced cell invasion and binding to and activation of ADP ribosylation factor 1 associated with tumor formation. Mutational analysis indicate that EGF-triggered phosphorylation of Thr8 within the SAM domain prevents AKT binding and antagonizes CNK1-mediated AKT signaling. Our findings reveal SAM domain-dependent oligomerization by AKT as switch for CNK1 activation.
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Affiliation(s)
- Adrian Fischer
- Department of Biochemistry and Synthetic Biology, Faculty of Biology, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany; Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany; BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
| | - Wilfried Weber
- Department of Biochemistry and Synthetic Biology, Faculty of Biology, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany; Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
| | - Bettina Warscheid
- Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany; BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
| | - Gerald Radziwill
- Department of Biochemistry and Synthetic Biology, Faculty of Biology, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany; Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany; BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
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11
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Optogenetically controlled RAF to characterize BRAF and CRAF protein kinase inhibitors. Sci Rep 2016; 6:23713. [PMID: 27025703 PMCID: PMC4812324 DOI: 10.1038/srep23713] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/14/2016] [Indexed: 12/19/2022] Open
Abstract
Here, we applied optoRAF, an optogenetic tool for light-controlled clustering and activation of RAF proteins that mimics the natural occurring RAS-mediated dimerization. This versatile tool allows studying the effect on BRAF and CRAF homodimer- as well as heterodimer-induced RAF signaling. Vemurafenib and dabrafenib are two clinically approved inhibitors for BRAF that efficiently suppress the kinase activity of oncogenic BRAF (V600E). However in wild-type BRAF expressing cells, BRAF inhibitors can exert paradoxical activation of wild-type CRAF. Using optoRAF, vemurafenib was identified as paradoxical activator of BRAF and CRAF homo- and heterodimers. Dabrafenib enhanced activity of light-stimulated CRAF at low dose and inhibited CRAF signaling at high dose. Moreover, dabrafenib increased the protein level of CRAF proteins but not of BRAF proteins. Increased CRAF levels correlate with elevated RAF signaling in a dabrafenib-dependent manner, independent of light activation.
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12
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Differential tyrosine phosphorylation controls the function of CNK1 as a molecular switch in signal transduction. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2847-55. [PMID: 26319181 DOI: 10.1016/j.bbamcr.2015.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/21/2015] [Accepted: 08/24/2015] [Indexed: 11/22/2022]
Abstract
Scaffold proteins are multidomain proteins without enzymatic function that play a central role in coordinating signaling processes. The scaffold protein CNK1 interacts with pathway-specific signaling proteins and thereby regulates these respective pathways. Here, we revealed tyrosine phosphorylation as a critical regulation mechanism to control the function of CNK1. We identified Tyr 26 as a PDGF-induced and, additionally, Tyr 519 and Tyr 665 as SRC-induced tyrosine phosphorylation sites. Phosphomimetic mutants indicate that phosphorylation of Tyr 519 recruits CNK1 to the nucleus and additional phosphorylation of Tyr 26 enables CNK1 to promote SRE-dependent gene expression. Contrary, mutants preventing tyrosine phosphorylation promote matrix metalloproteinase MMP14 promoter activity. CNK1-driven cell proliferation partially depends on its tyrosine phosphorylation. Upon PDGF stimulation, CNK1 is recruited to the plasma membrane mediated by SRC. Knock down of CNK1 prevents PDGF-induced SRE-dependent gene expression, MMP14 promoter activity and cell proliferation. Thus, tyrosine phosphorylation is an important mechanism to control the subcellular localization of CNK1 and its distinct biological functions.
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13
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Sanhueza M, Chai A, Smith C, McCray BA, Simpson TI, Taylor JP, Pennetta G. Network analyses reveal novel aspects of ALS pathogenesis. PLoS Genet 2015; 11:e1005107. [PMID: 25826266 PMCID: PMC4380362 DOI: 10.1371/journal.pgen.1005107] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 02/27/2015] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by selective loss of motor neurons, muscle atrophy and paralysis. Mutations in the human VAMP-associated protein B (hVAPB) cause a heterogeneous group of motor neuron diseases including ALS8. Despite extensive research, the molecular mechanisms underlying ALS pathogenesis remain largely unknown. Genetic screens for key interactors of hVAPB activity in the intact nervous system, however, represent a fundamental approach towards understanding the in vivo function of hVAPB and its role in ALS pathogenesis. Targeted expression of the disease-causing allele leads to neurodegeneration and progressive decline in motor performance when expressed in the adult Drosophila, eye or in its entire nervous system, respectively. By using these two phenotypic readouts, we carried out a systematic survey of the Drosophila genome to identify modifiers of hVAPB-induced neurotoxicity. Modifiers cluster in a diverse array of biological functions including processes and genes that have been previously linked to hVAPB function, such as proteolysis and vesicular trafficking. In addition to established mechanisms, the screen identified endocytic trafficking and genes controlling proliferation and apoptosis as potent modifiers of ALS8-mediated defects. Surprisingly, the list of modifiers was mostly enriched for proteins linked to lipid droplet biogenesis and dynamics. Computational analysis reveals that most modifiers can be linked into a complex network of interacting genes, and that the human genes homologous to the Drosophila modifiers can be assembled into an interacting network largely overlapping with that in flies. Identity markers of the endocytic process were also found to abnormally accumulate in ALS patients, further supporting the relevance of the fly data for human biology. Collectively, these results not only lead to a better understanding of hVAPB function but also point to potentially relevant targets for therapeutic intervention. Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease causing loss of motor neurons and consequently a progressive deterioration of motor functions. ALS is uniformly fatal with death occurring 5 years after onset of symptoms. There is currently no effective treatment for ALS. Several mutations in a gene called hVAPB have shown that this gene is causative of a type of ALS known as ALS8. In this study we sought to identify genes and cellular processes that are involved in the toxicity conferred by the defective ALS8 allele. By using the power of Drosophila genetics, we performed a large scale genomic screen and identified a number of genes that can affect hVAPB-mediated toxicity. These modifiers cluster into functional pathways known to be involved in ALS as well as novel ones. The relevance of these modifiers and mechanisms for the human disease was confirmed by showing that the human homologues of the fly modifiers can be organized into a network that closely resembles that of the Drosophila genes. Identifying cellular processes and proteins that modulate hVAPB pathological activity can facilitate the discovery of an effective treatment for ALS.
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Affiliation(s)
- Mario Sanhueza
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrea Chai
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Houston, Texas, United States of America
| | - Colin Smith
- Academic Department of Neuropathology, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Brett A. McCray
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Cambridge, Massachusetts, United States of America
| | - T. Ian Simpson
- Biomathematics and Statistics Scotland, University of Edinburgh, United Kingdom
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, United Kingdom
| | - J. Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Giuseppa Pennetta
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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14
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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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15
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Wend S, Wagner HJ, Müller K, Zurbriggen MD, Weber W, Radziwill G. Optogenetic control of protein kinase activity in mammalian cells. ACS Synth Biol 2014; 3:280-5. [PMID: 24090449 DOI: 10.1021/sb400090s] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Light-dependent dimerization is the basis for recently developed noninvasive optogenetic tools. Here we present a novel tool combining optogenetics with the control of protein kinase activity to investigate signal transduction pathways. Mediated by Arabidopsis thaliana photoreceptor cryptochrome 2, we activated the protein kinase C-RAF by blue light-dependent dimerization, allowing for decoupling from upstream signaling events induced by surface receptors. The activation by light is fast, reversible, and not only time but also dose dependent as monitored by phosphorylation of ERK1/2. Additionally, light-activated C-RAF controls serum response factor-mediated gene expression. Light-induced heterodimerization of C-RAF with a kinase-dead mutant of B-RAF demonstrates the enhancing role of B-RAF as a scaffold for C-RAF activity, which leads to the paradoxical activation of C-RAF found in human cancers. This optogenetic tool enables reversible control of protein kinase activity in signal duration and strength. These properties can help to shed light onto downstream signaling processes of protein kinases in living cells.
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Affiliation(s)
- Sabrina Wend
- Faculty
of Biology, University of Freiburg, 79104 Freiburg, Germany
- Spemann
Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg, Germany
| | - Hanna J. Wagner
- Faculty
of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Konrad Müller
- Faculty
of Biology, University of Freiburg, 79104 Freiburg, Germany
| | | | - Wilfried Weber
- Faculty
of Biology, University of Freiburg, 79104 Freiburg, Germany
- Spemann
Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg, Germany
- BIOSS
Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Gerald Radziwill
- Faculty
of Biology, University of Freiburg, 79104 Freiburg, Germany
- BIOSS
Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
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16
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Cho HJ, Hwang YS, Mood K, Ji YJ, Lim J, Morrison DK, Daar IO. EphrinB1 interacts with CNK1 and promotes cell migration through c-Jun N-terminal kinase (JNK) activation. J Biol Chem 2014; 289:18556-68. [PMID: 24825906 DOI: 10.1074/jbc.m114.558809] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Eph receptors and their membrane-bound ligands, ephrins, play important roles in various biological processes such as cell adhesion and movement. The transmembrane ephrinBs transduce reverse signaling in a tyrosine phosphorylation-dependent or -independent, as well as PDZ-dependent manner. Here, we show that ephrinB1 interacts with Connector Enhancer of KSR1 (CNK1) in an EphB receptor-independent manner. In cultured cells, cotransfection of ephrinB1 with CNK1 increases JNK phosphorylation. EphrinB1/CNK1-mediated JNK activation is reduced by overexpression of dominant-negative RhoA. Overexpression of CNK1 alone is sufficient for activation of RhoA; however, both ephrinB1 and CNK1 are required for JNK phosphorylation. Co-immunoprecipitation data showed that ephrinB1 and CNK1 act as scaffold proteins that connect RhoA and JNK signaling components, such as p115RhoGEF and MKK4. Furthermore, adhesion to fibronectin or active Src overexpression increases ephrinB1/CNK1 binding, whereas blocking Src activity by a pharmacological inhibitor decreases not only ephrinB1/CNK1 binding, but also JNK activation. EphrinB1 overexpression increases cell motility, however, CNK1 depletion by siRNA abrogates ephrinB1-mediated cell migration and JNK activation. Moreover, Rho kinase inhibitor or JNK inhibitor treatment suppresses ephrinB1-mediated cell migration. Taken together, our findings suggest that CNK1 is required for ephrinB1-induced JNK activation and cell migration.
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Affiliation(s)
- Hee Jun Cho
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Yoo-Seok Hwang
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Kathleen Mood
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Yon Ju Ji
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Junghwa Lim
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Deborah K Morrison
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
| | - Ira O Daar
- From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702
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17
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Robinson JD, Pitcher JA. G protein-coupled receptor kinase 2 (GRK2) is a Rho-activated scaffold protein for the ERK MAP kinase cascade. Cell Signal 2013; 25:2831-9. [PMID: 24018045 DOI: 10.1016/j.cellsig.2013.08.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 08/30/2013] [Accepted: 08/31/2013] [Indexed: 11/20/2022]
Abstract
The G protein-coupled receptor kinases (GRKs) are best known for their role in phosphorylating and desensitising G protein-coupled receptors (GPCRs). The GRKs also regulate signalling downstream of other families of receptors and have a number of non-receptor substrates and binding partners. Here we identify RhoAGTP and Raf1 as novel binding partners of GRK2 and report a previously unsuspected function for this kinase. GRK2 is a RhoA effector that serves as a RhoA-activated scaffold protein for the ERK MAP kinase cascade. The ability of GRK2 to bind to Raf1, MEK1 and ERK2 is dependent on RhoAGTP binding to the catalytic domain of the kinase. Exogenous GRK2 has previously been shown to increase ERK activation downstream of the epidermal growth factor receptor (EGFR). Here we find that GRK2-mediated ERK activation downstream of the EGFR is Rho-dependent and that treatment with EGF promotes RhoAGTP binding and ERK scaffolding by GRK2. Depletion of GRK2 expression by RNAi reveals that GRK2 is required for EGF-induced, Rho- and ERK-dependent thymidine incorporation in vascular smooth muscle cells (VSMCs). We therefore hypothesise that Rho-dependent ERK MAPK scaffolding by GRK2 downstream of the EGFR may have an important role in the vasculature, where increased levels of both GRK2 and RhoA have been associated with hypertension.
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Affiliation(s)
- James D Robinson
- MRC Laboratory for Molecular Cell Biology, Research Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
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18
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Abe H, Mochizuki S, Ohara K, Ueno M, Ochiai H, Kitagawa Y, Hino O, Sato H, Okada Y. Src plays a key role in ADAM28 expression in v-src-transformed epithelial cells and human carcinoma cells. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:1667-1678. [PMID: 24007880 DOI: 10.1016/j.ajpath.2013.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 10/26/2022]
Abstract
ADAM28, a disintegrin and metalloproteinase 28, is overexpressed by carcinoma cells with direct correlations with carcinoma cell proliferation and progression in human lung and breast carcinomas. However, the molecular mechanisms of ADAM28 gene expression in carcinoma cells remain elusive. Herein, we investigated the expression of ADAM28 in Madin-Darby canine kidney epithelial cells transformed by oncogenes, including v-src, LMP1, ErbB2, Ha-Ras, and c-Fos, and found that v-src transformants selectively induce ADAM28. Implantation of the v-src transformants showed a progressively growing tumor, which was significantly suppressed by local injections of anti-ADAM28 antibody. ADAM28 expression in v-src transformants was partially inhibited by treatment with inhibitors to Src kinase, mitogen-activated protein kinase kinase (MEK), phosphatidylinositol 3-kinase (PI3K), or mammalian target of rapamycin, and abrogated by v-Src kinase inhibitor, radicicol, or a mixture of MEK and PI3K inhibitors. Human carcinoma cell lines of the lung, breast, ovary, kidney, and colon showed ADAM28 expression, which was correlated with phosphorylation of c-Src and suppressed by the inhibitors in a similar way to v-src transformants. IHC of the human tumor tissues demonstrated co-expression of ADAM28 and phosphorylated Src in neoplastic cells of the breast, lung, and colon carcinomas and some adenomas of the colon, but not in nonneoplastic colon mucosa. Our data provide, to the best of our knowledge, the first evidence that Src is an inducer of ADAM28 gene expression through the MEK/extracellular signal-regulated kinase and PI3K/mammalian target of rapamycin pathways.
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Affiliation(s)
- Hitoshi Abe
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan; Department of Pathology and Oncology, School of Medicine, Juntendo University, Tokyo, Japan
| | - Satsuki Mochizuki
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
| | - Kentaro Ohara
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
| | - Mari Ueno
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
| | - Hiroki Ochiai
- Department of Surgery, School of Medicine, Keio University, Tokyo, Japan
| | - Yuko Kitagawa
- Department of Surgery, School of Medicine, Keio University, Tokyo, Japan
| | - Okio Hino
- Department of Pathology and Oncology, School of Medicine, Juntendo University, Tokyo, Japan
| | - Hiroshi Sato
- Department of Molecular Virology and Oncology, Cancer Research Institute, Kanazawa University, Kanazawa, Japan
| | - Yasunori Okada
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan.
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19
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Matallanas D, Birtwistle M, Romano D, Zebisch A, Rauch J, von Kriegsheim A, Kolch W. Raf family kinases: old dogs have learned new tricks. Genes Cancer 2011; 2:232-60. [PMID: 21779496 PMCID: PMC3128629 DOI: 10.1177/1947601911407323] [Citation(s) in RCA: 272] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
First identified in the early 1980s as retroviral oncogenes, the Raf proteins have been the objects of intense research. The discoveries 10 years later that the Raf family members (Raf-1, B-Raf, and A-Raf) are bona fide Ras effectors and upstream activators of the ubiquitous ERK pathway increased the interest in these proteins primarily because of the central role that this cascade plays in cancer development. The important role of Raf in cancer was corroborated in 2002 with the discovery of B-Raf genetic mutations in a large number of tumors. This led to intensified drug development efforts to target Raf signaling in cancer. This work yielded not only recent clinical successes but also surprising insights into the regulation of Raf proteins by homodimerization and heterodimerization. Surprising insights also came from the hunt for new Raf targets. Although MEK remains the only widely accepted Raf substrate, new kinase-independent roles for Raf proteins have emerged. These include the regulation of apoptosis by suppressing the activity of the proapoptotic kinases, ASK1 and MST2, and the regulation of cell motility and differentiation by controlling the activity of Rok-α. In this review, we discuss the regulation of Raf proteins and their role in cancer, with special focus on the interacting proteins that modulate Raf signaling. We also describe the new pathways controlled by Raf proteins and summarize the successes and failures in the development of efficient anticancer therapies targeting Raf. Finally, we also argue for the necessity of more systemic approaches to obtain a better understanding of how the Ras-Raf signaling network generates biological specificity.
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Affiliation(s)
- David Matallanas
- Systems Biology Ireland, University College Dublin, Dublin, Ireland
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20
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Fritz RD, Radziwill G. CNK1 and other scaffolds for Akt/FoxO signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1971-7. [PMID: 21320536 DOI: 10.1016/j.bbamcr.2011.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 02/01/2011] [Accepted: 02/05/2011] [Indexed: 11/28/2022]
Abstract
FoxO transcription factors mediate anti-proliferative and pro-apoptotic signals and act as tumor suppressors in cancer. Posttranslational modifications including phosphorylation and acetylation regulate FoxO activity by a cytoplasmic-nuclear shuttle mechanism. Scaffold proteins coordinating signaling pathways in time and space play a critical role in this process. CNK1 acts as a scaffold protein in several signaling pathways controlling the function of FoxO proteins. An understanding of CNK1 and other scaffolds in the FoxO signaling network will provide insights how to release the tumor suppressor function of FoxO as a possibility to block oncogenic pathways. This article is part of a Special Issue entitled: P13K-AKT-FoxO axis in cancer and aging.
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Affiliation(s)
- Rafael D Fritz
- Department of Biomedicine, Institute of Biochemistry and Genetics, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland.
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21
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Udell CM, Rajakulendran T, Sicheri F, Therrien M. Mechanistic principles of RAF kinase signaling. Cell Mol Life Sci 2011; 68:553-65. [PMID: 20820846 PMCID: PMC11114552 DOI: 10.1007/s00018-010-0520-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 08/24/2010] [Accepted: 08/25/2010] [Indexed: 12/19/2022]
Abstract
The RAF family of kinases are key components acting downstream of receptor tyrosine kinases and cells employ several distinct mechanisms to strictly control their activity. RAF transitions from an inactive state, where the N-terminal regulatory region binds intramolecularly to the C-terminal kinase domain, to an open state capable of executing the phosphoryl transfer reaction. This transition involves changes both within and between the protein domains in RAF. Many different proteins regulate the transition between inactive and active states of RAF, including RAS and KSR, which are arguably the two most prominent regulators of RAF function. Recent developments have added several new twists to our understanding of RAF regulation. Among others, dimerization of the RAF kinase domain is emerging as a crucial step in the RAF activation process. The multitude of regulatory protein-protein interactions involving RAF remains a largely untapped area for therapeutic applications.
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Affiliation(s)
- Christian M. Udell
- Laboratory of Intracellular Signaling, Département de pathologie et de biologie cellulaire, Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC H3C 3J7 Canada
| | - Thanashan Rajakulendran
- Centre for Systems Biology, Samuel Lunenfeld Research Institute, Toronto, ON M5G 1X5 Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Frank Sicheri
- Centre for Systems Biology, Samuel Lunenfeld Research Institute, Toronto, ON M5G 1X5 Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Marc Therrien
- Laboratory of Intracellular Signaling, Département de pathologie et de biologie cellulaire, Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC H3C 3J7 Canada
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22
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Lim J, Zhou M, Veenstra TD, Morrison DK. The CNK1 scaffold binds cytohesins and promotes insulin pathway signaling. Genes Dev 2010; 24:1496-506. [PMID: 20634316 DOI: 10.1101/gad.1904610] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Protein scaffolds play an important role in signal transduction, regulating the localization of signaling components and mediating key protein interactions. Here, we report that the major binding partners of the Connector Enhancer of KSR 1 (CNK1) scaffold are members of the cytohesin family of Arf guanine nucleotide exchange factors, and that the CNK1/cytohesin interaction is critical for activation of the PI3K/AKT cascade downstream from insulin and insulin-like growth factor 1 (IGF-1) receptors. We identified a domain located in the C-terminal region of CNK1 that interacts constitutively with the coiled-coil domain of the cytohesins, and found that CNK1 facilitates the membrane recruitment of cytohesin-2 following insulin stimulation. Moreover, through protein depletion and rescue experiments, we found that the CNK1/cytohesin interaction promotes signaling from plasma membrane-bound Arf GTPases to the phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks) to generate a PIP(2)-rich microenvironment that is critical for the membrane recruitment of insulin receptor substrate 1 (IRS1) and signal transmission to the PI3K/AKT cascade. These findings identify CNK1 as a new positive regulator of insulin signaling.
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Affiliation(s)
- Junghwa Lim
- Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, Frederick, Maryland 21702, USA
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23
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CNK1 is a novel Akt interaction partner that promotes cell proliferation through the Akt-FoxO signalling axis. Oncogene 2010; 29:3575-82. [DOI: 10.1038/onc.2010.104] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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24
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Fritz RD, Radziwill G. CNK1 Promotes Invasion of Cancer Cells through NF-κB–Dependent Signaling. Mol Cancer Res 2010; 8:395-406. [DOI: 10.1158/1541-7786.mcr-09-0296] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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25
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Gringhuis SI, den Dunnen J, Litjens M, van der Vlist M, Geijtenbeek TBH. Carbohydrate-specific signaling through the DC-SIGN signalosome tailors immunity to Mycobacterium tuberculosis, HIV-1 and Helicobacter pylori. Nat Immunol 2009; 10:1081-8. [PMID: 19718030 DOI: 10.1038/ni.1778] [Citation(s) in RCA: 335] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Accepted: 07/07/2009] [Indexed: 12/16/2022]
Abstract
Cooperation between different innate signaling pathways induced by pattern-recognition receptors (PRRs) on dendritic cells (DCs) is crucial for tailoring adaptive immunity to pathogens. Here we show that carbohydrate-specific signaling through the C-type lectin DC-SIGN tailored cytokine production in response to distinct pathogens. DC-SIGN was constitutively associated with a signalosome complex consisting of the scaffold proteins LSP1, KSR1 and CNK and the kinase Raf-1. Mannose-expressing Mycobacterium tuberculosis and human immunodeficiency virus type 1 (HIV-1) induced the recruitment of effector proteins to the DC-SIGN signalosome to activate Raf-1, whereas fucose-expressing pathogens such as Helicobacter pylori actively dissociated the KSR1-CNK-Raf-1 complex from the DC-SIGN signalosome. This dynamic regulation of the signalosome by mannose- and fucose-expressing pathogens led to the enhancement or suppression of proinflammatory responses, respectively. Our study reveals another level of plasticity in tailoring adaptive immunity to pathogens.
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Affiliation(s)
- Sonja I Gringhuis
- Center of Infection and Immunity Amsterdam, University of Amsterdam, Amsterdam, The Netherlands.
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26
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Cakir M, Grossman AB. Targeting MAPK (Ras/ERK) and PI3K/Akt pathways in pituitary tumorigenesis. Expert Opin Ther Targets 2009; 13:1121-34. [DOI: 10.1517/14728220903170675] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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Ziera T, Irlbacher H, Fromm A, Latouche C, Krug SM, Fromm M, Jaisser F, Borden SA. Cnksr3 is a direct mineralocorticoid receptor target gene and plays a key role in the regulation of the epithelial sodium channel. FASEB J 2009; 23:3936-46. [PMID: 19567370 DOI: 10.1096/fj.09-134759] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Aldosterone is the principal hormonal regulator of sodium homeostasis in vertebrates. It exerts its actions through the mineralocorticoid receptor (MR) that regulates the transcription of specific target genes. In recent years, a number of MR target genes have been identified that are involved in the regulation of the epithelial sodium channel (ENaC), a key modulator of renal sodium absorption. Here we report the identification of cnksr3 as a direct MR target gene that is up-regulated in response to physiological concentrations of aldosterone. The cnksr3 promoter exhibits two functional aldosterone-responsive regions, which were bound by the MR as assessed by chromatin immunoprecipitation (ChIP). In vivo, CNKSR3 was highly expressed in the renal cortical collecting duct (CCD), the prime target segment of aldosterone-regulated sodium retention in the kidney. CCD cell lines stably overexpressing or silencing CNKSR3 were electrophysiologically analyzed and show that CNKSR3 expression correlated with and is required for ENaC-mediated transepithelial sodium transport. In parallel, CNKSR3 expression led to decreased MEK phosphorylation. We conclude that CNKSR3, a homologue of scaffold proteins involved in MAPK pathway regulation, is a direct target of MR and is required for the maintenance of transepithelial sodium transport in the kidney.
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Affiliation(s)
- Tim Ziera
- Therapeutic Research Women's Health, Bayer Schering Pharma AG, Müllerstr. 178, 13353 Berlin, Germany
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28
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Cournoyer P, Desrosiers RR. Valproic acid enhances protein L-isoaspartyl methyltransferase expression by stimulating extracellular signal-regulated kinase signaling pathway. Neuropharmacology 2009; 56:839-48. [PMID: 19371592 DOI: 10.1016/j.neuropharm.2009.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 01/06/2009] [Accepted: 01/09/2009] [Indexed: 11/29/2022]
Abstract
Proteins are susceptible to various non-enzymatic post-translational modifications occurring during aging and in certain pathological states. The protein L-isoaspartyl methyltransferase (PIMT) is an enzyme that recognizes and repairs the abnormal L-isoaspartyl residues in proteins. Recently, we reported that PIMT expression was stimulated by the anti-epileptic drug valproic acid and that this was mediated through the glycogen synthase kinase-3 (GSK-3)/beta-catenin pathway. In this study, to gain further insights into which of the signaling pathways activated by valproic acid regulate PIMT abundance, astrocytoma U-87 MG and neuroblastoma SH-SY5Y cells were treated with this drug to investigate the possible involvement of the extracellular-regulated kinase (ERK) pathway in PIMT induction. Valproic acid increased ERK1/2 phosphorylation on Thr202/Tyr204 and Thr185/Tyr187, respectively. Pharmacological inhibitors against the kinases Src, c-Raf, MEK1/2 and ERK1/2 abolished the ERK1/2 phosphorylation stimulated by valproic acid, thus preventing PIMT induction by the drug. Furthermore, MEK1/2 inhibition with U0126 blocked the higher phosphorylation of RSK-1 on Thr359/Ser363 and of GSK-3beta on Ser9 as well as the increased expression of RSK-1, beta-catenin and PIMT upon treatment with valproic acid. RSK-1 knockdown by interfering RNA abrogated the increased expression of RSK-1, beta-catenin and PIMT as well as the induced phosphorylation of RSK-1 and GSK-3beta due to valproic acid. Thus, our findings demonstrated that PIMT up-regulation by valproic acid required the activation of the ERK signaling pathway including RSK-1 the latter being responsible for inactivating GSK-3 and subsequently leading to beta-catenin stabilization.
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Affiliation(s)
- Philippe Cournoyer
- Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal, Québec, Canada H3C 3P8
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29
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Bhaskaran N, Souchelnytskyi S. Systemic analysis of TGFbeta proteomics revealed involvement of Plag1/CNK1/RASSF1A/Src network in TGFbeta1-dependent activation of Erk1/2 and cell proliferation. Proteomics 2008; 8:4507-20. [PMID: 18821524 DOI: 10.1002/pmic.200700960] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transforming growth factor-beta (TGFbeta) is a key regulator of cell proliferation, death, migration, and differentiation. To explore mechanisms of TGFbeta action, we performed systemic analysis of functional dependencies between 153 proteins which changed their expression and synthesis upon treatment of human breast epithelial cells with TGFbeta1. We found that TGFbeta1 initiated signaling via a scale-free network of proteins which affect primary cellular metabolism, stress response, signal transduction, transport, transcription, cytoskeleton, and cell death. Multiple inputs into each functional domain were observed, emphasizing robustness of TGFbeta1 signaling. Network analysis demonstrated importance of a Plag1/CNK1/RASSF1A/Src-dependent prozone effect, as a systemic feature which is crucial for TGFbeta1-dependent activation of Erk1/2 and regulation of cell proliferation. We showed that the balance between Plag1, CNK1, RASSF1A and Src defined whether TGFbeta1 will stimulate, inhibit or will have no effect on a long-term activation of Erk1/2 and subsequent TGFbeta1 inhibitory or stimulatory effect on cell proliferation. This is the first demonstration of importance of systemic features for incorporation of Erk1/2 activation into TGFbeta1 signaling.
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Affiliation(s)
- Nimesh Bhaskaran
- Department of Oncology-Pathology, Karolinska Biomics Center, Karolinska Institute, Karolinska University Hospital, Solna, Stockholm, Sweden
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30
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Eichhorn PJA, Creyghton MP, Bernards R. Protein phosphatase 2A regulatory subunits and cancer. Biochim Biophys Acta Rev Cancer 2008; 1795:1-15. [PMID: 18588945 DOI: 10.1016/j.bbcan.2008.05.005] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/20/2008] [Accepted: 05/21/2008] [Indexed: 01/06/2023]
Abstract
The serine/threonine protein phosphatase (PP2A) is a trimeric holoenzyme that plays an integral role in the regulation of a number of major signaling pathways whose deregulation can contribute to cancer. The specificity and activity of PP2A are highly regulated through the interaction of a family of regulatory B subunits with the substrates. Accumulating evidence indicates that PP2A acts as a tumor suppressor. In this review we summarize the known effects of specific PP2A holoenzymes and their roles in cancer relevant pathways. In particular we highlight PP2A function in the regulation of MAPK and Wnt signaling.
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Affiliation(s)
- Pieter J A Eichhorn
- Division of Molecular Carcinogenesis, Center for Cancer Genomics and Center for Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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31
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Ramos JW. The regulation of extracellular signal-regulated kinase (ERK) in mammalian cells. Int J Biochem Cell Biol 2008; 40:2707-19. [PMID: 18562239 DOI: 10.1016/j.biocel.2008.04.009] [Citation(s) in RCA: 354] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/18/2008] [Accepted: 04/25/2008] [Indexed: 01/03/2023]
Abstract
The mitogen-activated protein (MAP) kinase extracellular-signal-regulated kinases (ERKs) are activated by diverse mechanisms. These include ligation of receptor tyrosine kinases such as epidermal growth factor (EGF) and cell adhesion receptors such as the integrins. In general, ligand binding of these receptors leads to GTP loading and activation of the small GTPase Ras, which recruits Raf to the membrane where it is activated. Raf subsequently phosphorylates the dual specificity MAP/ERK kinase (MEK1/2) which in turn phosphorylates and thereby activates ERK. ERK is a promiscuous kinase and can phosphorylate more than 100 different substrates. Therefore activation of ERK can affect a broad array of cellular functions including proliferation, survival, apoptosis, motility, transcription, metabolism and differentiation. ERK activity is controlled by many distinct mechanisms. Scaffold proteins control when and where ERK is activated while anchoring proteins can restrain ERK localization to specific subcellular compartments. Meanwhile, phosphatases dephosphorylate and inactivate ERK thereby shutting off the pathway. Finally, several feedback mechanisms have been identified downstream of ERK activation. Here we will focus on the diverse mechanisms of ERK regulation in mammalian cells.
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Affiliation(s)
- Joe W Ramos
- Department of Natural Products and Cancer Biology, Cancer Research Center of Hawaii, University of Hawaii at Manoa, 651 Ilalo Street, Honolulu, HI 96813, USA.
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32
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Abstract
Mitogen-activated protein kinases (MAPKs) regulate critical signaling pathways involved in cell proliferation, differentiation and apoptosis. Recent studies have shown that a novel class of scaffold proteins mediates the structural and functional organization of the three-tier MAPK module. By linking the MAP3K, MAP2K and MAPK into a multienzyme complex, these MAPK-specific scaffold proteins provide an insulated physical conduit through which signals from the respective MAPK can be transmitted to the appropriate spatiotemporal cellular loci. Scaffold proteins play a determinant role in modulating the signaling strength of their cognate MAPK module by regulating the signal amplitude and duration. The scaffold proteins themselves are finely regulated resulting in dynamic intra- and inter-molecular interactions that can modulate the signaling outputs of MAPK modules. This review focuses on defining the diverse mechanisms by which these scaffold proteins interact with their respective MAPK modules and the role of such interactions in the spatiotemporal organization as well as context-specific signaling of the different MAPK modules.
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Affiliation(s)
- D N Dhanasekaran
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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33
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Abstract
Signals received at the cell surface must be properly transmitted to critical targets within the cell to achieve the appropriate biological response. This process of signal transduction is often initiated by receptor tyrosine kinases (RTKs), which function as entry points for many extracellular cues and play a critical role in recruiting the intracellular signaling cascades that orchestrate a particular response. Essential for most RTK-mediated signaling is the engagement and activation of the mitogen-activated protein kinase (MAPK) cascade comprised of the Raf, MEK and extracellular signal-regulated kinase (ERK) kinases. For many years, it was thought that signaling from RTKs to ERK occurred only at the plasma membrane and was mediated by a simple, linear Ras-dependent pathway. However, the limitation of this model became apparent with the discovery that Ras and ERK can be activated at various intracellular compartments, and that RTKs can modulate Ras/ERK signaling from these sites. Moreover, ERK scaffolding proteins and signaling modulators have been identified that play critical roles in determining the strength, duration and location of RTK-mediated ERK signaling. Together, these factors contribute to the diversity of biological responses generated by RTK signaling.
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Affiliation(s)
- M M McKay
- Laboratory of Cell and Developmental Signaling, NCI-Frederick, Frederick, MD 21702, USA
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34
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Wren JD, Wu Y, Guo SW. A system-wide analysis of differentially expressed genes in ectopic and eutopic endometrium. Hum Reprod 2007; 22:2093-102. [PMID: 17562676 DOI: 10.1093/humrep/dem129] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Decades of research suggest that endometriosis is a complex disorder, with varying severity, onset and progression. Many genes have been associated with endometriosis through a number of studies and now microarray analyses have added to the list of perturbed or differentially regulated genes. Thus, it is difficult to see 'the big picture' without first integrating these multiple, heterogeneous sources of high-quality information for analysis. METHODS The goal of this study was to infer correlative and/or causal trends by combining empirical microarray analysis with a historical knowledge base of genetic relationships in endometriosis via a program called IRIDESCENT. RESULTS Importantly, we found a number of genes, which may have a central role in endometriosis, despite the fact that few or no past studies have reported these associations. CONCLUSIONS Several genes listed as non-responders on the microarray were found to be regulated post-transcriptionally, illustrating the importance of integrating multiple data sources.
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Affiliation(s)
- Jonathan D Wren
- Arthritis and Immunology Research Program, Oklahoma Medical Research Foundation, 825 N.E. 13th Street, Oklahoma City, OK 73104-5005, USA.
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35
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Abstract
The RAS-RAF-MEK-extracellular-regulated kinase (RAS/ERK) pathway is a major intracellular route used by metazoan cells to channel to downstream targets a diverse array of signals, including those controlling cell proliferation and survival. Recent findings suggest that the pathway is assembled by specific scaffolding proteins that in turn regulate the efficiency, the location and/or the duration of signal transmission. Here, through the angle of studies conducted in Drosophila and C. elegans, we present two such proteins, the kinase suppressor of RAS (KSR) and connector enhancer of KSR (CNK) scaffolds, and highlight their implication in a novel mechanism regulating RAS-mediated RAF activation. Based on recent findings, we discuss the possibility that KSR, a RAF-like protein, does not solely act as a scaffold, but directly induces RAF catalytic function by a kinase-independent mechanism apparently shared by RAF-like proteins.
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Affiliation(s)
- A Clapéron
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal CP, Montréal, Québec, Canada
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36
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Radziwill G, Weiss A, Heinrich J, Baumgartner M, Boisguerin P, Owada K, Moelling K. Regulation of c-Src by binding to the PDZ domain of AF-6. EMBO J 2007; 26:2633-44. [PMID: 17491594 PMCID: PMC1888668 DOI: 10.1038/sj.emboj.7601706] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 04/10/2007] [Indexed: 11/09/2022] Open
Abstract
c-Src is a tightly regulated non-receptor tyrosine kinase. We describe the C-terminus of c-Src as a ligand for a PDZ (postsynaptic density 95, PSD-95; discs large, Dlg; zonula occludens-1, ZO-1) domain. The C-terminal residue Leu of c-Src is essential for binding to a PDZ domain. Mutation of this residue does not affect the intrinsic kinase activity in vitro, but interferes with c-Src regulation in cells. As a candidate PDZ protein, we analysed AF-6, a junctional adhesion protein. The AF-6 PDZ domain restricts the number of c-Src substrates, whereas knockdown of AF-6 has the opposite effect. Binding of c-Src to the AF-6 PDZ domain interferes with phosphorylation of c-Src at Tyr527 by the C-terminal kinase, and reduces c-Src autophosphorylation at Tyr416, resulting in a moderately activated c-Src kinase. Unphosphorylated Tyr527 allows binding of c-Src to AF-6. This can be overcome by overexpression of CSK or strong activation of c-Src. c-Src is recruited by AF-6 to cell-cell contact sites, suggesting that c-Src is regulated by a PDZ protein in special cellular locations. We identified a novel type of c-Src regulation by interaction with a PDZ protein.
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Affiliation(s)
- Gerald Radziwill
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Gloriastrasse 30/32, Zurich 8006, Switzerland. Tel.: +41 44 634 2652/53; Fax: +41 44 634 4967; E-mail:
| | - Andreas Weiss
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Jochen Heinrich
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Martin Baumgartner
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | | | - Koji Owada
- Department of Molecular Bioregulation, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Karin Moelling
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Gloriastrasse 30/32, Zurich 8006, Switzerland. Tel.: +41 44 634 2652/53; Fax: +41 44 634 4967; E-mail:
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Wilkins-Port CE, Higgins CE, Freytag J, Higgins SP, Carlson JA, Higgins PJ. PAI-1 is a Critical Upstream Regulator of the TGF-beta1/EGF-Induced Invasive Phenotype in Mutant p53 Human Cutaneous Squamous Cell Carcinoma. J Biomed Biotechnol 2007; 2007:85208. [PMID: 17515947 PMCID: PMC1868077 DOI: 10.1155/2007/85208] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Accepted: 01/17/2007] [Indexed: 01/19/2023] Open
Abstract
The emergence of highly aggressive subtypes of human cutaneous squamous cell carcinoma (SCC) often reflects increased autocrine/paracrine TGF-β synthesis and epidermal growth factor receptor (EGFR) amplification. Cooperative TGF-β/EGFR signaling promotes cell migration and induces expression of both proteases and protease inhibitors that regulate stromal remodeling resulting in acquisition of an invasive phenotype. TGF-β1+EGF stimulation increases the production of several matrix metalloproteinases (MMPs) in human SCC. Among the most prominent is MMP-10 which is known to be elevated in SCC in situ. Activation of stromal plasminogen appears to be critical in triggering downstream MMP activity. Paradoxically, PAI-1, the major physiological inhibitor of plasmin generation, is also up-regulated under these conditions and is an early event in progression of incipient epidermal SCC. A model is proposed in which TGF-β1+EGF-dependent MMP-10 elevation directs focalized matrix remodeling events that promote epithelial cell plasticity and tissue invasion. Increased PAI-1 expression serves to temporally and spatially modulate plasmin-initiated pericellular proteolysis, further facilitating epithelial invasive potential. Defining the complex signaling mechanisms that maintain this elegant balance is critical to developing potential therapeutics for the treatment of human cutaneous malignancies.
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Affiliation(s)
- Cynthia E. Wilkins-Port
- Center for Cell Biology and Cancer Research, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
| | - Craig E. Higgins
- Center for Cell Biology and Cancer Research, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
| | - Jennifer Freytag
- Center for Cell Biology and Cancer Research, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
| | - Stephen P. Higgins
- Center for Cell Biology and Cancer Research, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
| | - J. Andrew Carlson
- Department of Pathology and Laboratory Medicine, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
| | - Paul J. Higgins
- Center for Cell Biology and Cancer Research, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
- Department of Pathology and Laboratory Medicine, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
- *Paul J. Higgins:
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Nguyen TK, Rahmani M, Harada H, Dent P, Grant S. MEK1/2 inhibitors sensitize Bcr/Abl+ human leukemia cells to the dual Abl/Src inhibitor BMS-354/825. Blood 2007; 109:4006-15. [PMID: 17218385 PMCID: PMC1874569 DOI: 10.1182/blood-2006-09-045039] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Interactions between MEK1/2 inhibitors and the dual Abl/Src kinase inhibitor dasatinib (BMS-354825) were examined in chronic myeloid leukemia (CML) cell lines and primary specimens. Cotreatment of K562 or LAMA cells with subtoxic or marginally toxic concentrations of PD184352 (or U0126) and dasatinib synergistically potentiated mitochondrial damage, caspase activation, and apoptosis. Similar interactions were observed in CD34(+) cells from one CML patient-derived but not in a normal human CD34(+) bone marrow cell specimen. These interactions were associated with multiple perturbations in survival signaling pathways, including inactivation of Bcr/Abl, STAT5, and ERK1/2; down-regulation of Bcl-x(L) and Mcl-1; and dephosphorylation/activation of Bim. They were also associated with BAX/BAK conformational change, mitochondrial dysfunction, and caspase activation. Bim knockdown by shRNA suppressed BAX and BAK conformational change and protected cells from dasatinib/PD184352 lethality. Conversely, K562 cells ectopically expressing Mcl-1 or Bcl-x(L) were significantly less susceptible to dasatinib/PD184352 toxicity. Notably, the dasatinib/PD184352 regimen was active against leukemic cells exhibiting various forms of imatinib mesylate resistance, including Bcr/Abl overexpression, Lyn activation, and several Bcr/Abl kinase domain mutations (eg, E255K, M351T), but not T315I. Together, these findings suggest that strategies combining dasatanib with MEK1/2 inhibitors warrant further investigation in Bcr/Abl(+) malignancies, particularly in the setting of imatinib mesylate-resistant disease.
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MESH Headings
- Benzamides/agonists
- Benzamides/pharmacology
- Butadienes/agonists
- Butadienes/pharmacology
- Dasatinib
- Drug Resistance, Neoplasm/drug effects
- Drug Resistance, Neoplasm/genetics
- Drug Screening Assays, Antitumor
- Drug Synergism
- Fusion Proteins, bcr-abl/antagonists & inhibitors
- Fusion Proteins, bcr-abl/metabolism
- Gene Expression Regulation, Leukemic/drug effects
- Gene Expression Regulation, Leukemic/genetics
- Humans
- Imatinib Mesylate
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/enzymology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- MAP Kinase Kinase 1/antagonists & inhibitors
- MAP Kinase Kinase 1/metabolism
- MAP Kinase Kinase 2/antagonists & inhibitors
- MAP Kinase Kinase 2/metabolism
- MAP Kinase Kinase 2/pharmacology
- Nitriles/agonists
- Nitriles/pharmacology
- Piperazines/pharmacology
- Piperazines/therapeutic use
- Protein Kinase Inhibitors/agonists
- Protein Kinase Inhibitors/pharmacology
- Pyrimidines/agonists
- Pyrimidines/pharmacology
- Pyrimidines/therapeutic use
- Thiazoles/agonists
- Thiazoles/pharmacology
- src-Family Kinases/antagonists & inhibitors
- src-Family Kinases/metabolism
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Affiliation(s)
- Tri K Nguyen
- Department of Medicine, Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
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Brummer T, Martin P, Herzog S, Misawa Y, Daly RJ, Reth M. Functional analysis of the regulatory requirements of B-Raf and the B-Raf(V600E) oncoprotein. Oncogene 2006; 25:6262-76. [PMID: 16702958 DOI: 10.1038/sj.onc.1209640] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The BRAF(V600E) mutation is found in approximately 6% of human cancers and mimics the phosphorylation of the kinase domain activation segment. In wild-type B-Raf (B-Raf(wt)), activation segment phosphorylation is thought to cooperate with negative charges within the N-region for full activation. In contrast to Raf-1, the N-region of B-Raf is constitutively negatively charged owing to the presence of residues D447/D448 and the phosphorylation of S446. Therefore, it has been suggested that this hallmark predisposes B-Raf for oncogenic activation. In this study, we demonstrate that neutralizing mutations of these residues (in particular S446 and S447), or uncoupling of B-Raf from Ras-guanine 5'-triphosphate (GTP), strongly reduce the biological activity of B-Raf in a PC12 cell differentiation assay. We also confirm that S365 is a 14-3-3 binding site, and determine that mutation of this residue rescues the impaired biological activity of B-Raf proteins with a neutralized N-region, suggesting that the N-region opposes a 14-3-3-mediated transition into an inactive conformation. However, in the case of B-Raf(V600E), although complete N-region neutralization resulted in a 2.5-fold reduction in kinase activity in vitro, this oncoprotein strongly induced PC12 differentiation or transformation and epithelial-mesenchymal transition of MCF-10A cells regardless of its N-region charge. Furthermore, the biological activity of B-Raf(V600E) was independent of its ability to bind Ras-GTP. Our analysis identifies important regulatory differences between B-Raf(wt) and B-Raf(V600E) and suggests that B-Raf(V600E) cannot be inhibited by strategies aimed at blocking S446 phosphorylation or Ras activation.
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Affiliation(s)
- T Brummer
- Cancer Research Program, The Garvan Institute of Medical Research, Sydney, NSW, Australia.
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40
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Douziech M, Sahmi M, Laberge G, Therrien M. A KSR/CNK complex mediated by HYP, a novel SAM domain-containing protein, regulates RAS-dependent RAF activation in Drosophila. Genes Dev 2006; 20:807-19. [PMID: 16600912 PMCID: PMC1472284 DOI: 10.1101/gad.1390406] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
RAF is a critical effector of the small GTPase RAS in normal and malignant cells. Despite intense scrutiny, the mechanism regulating RAF activation remains partially understood. Here, we show that the scaffold KSR (kinase suppressor of RAS), a RAF homolog known to assemble RAF/MEK/ERK complexes, induces RAF activation in Drosophila by a mechanism mediated by its kinase-like domain, but which is independent of its scaffolding property or putative kinase activity. Interestingly, we found that KSR is recruited to RAF prior to signal activation by the RAF-binding protein CNK (connector enhancer of KSR) in association with a novel SAM (sterile alpha motif) domain-containing protein, named Hyphen (HYP). Moreover, our data suggest that the interaction of KSR to CNK/HYP stimulates the RAS-dependent RAF-activating property of KSR. Together, these findings identify a novel protein complex that controls RAF activation and suggest that KSR does not only act as a scaffold for the MAPK (mitogen-activated protein kinase) module, but may also function as a RAF activator. By analogy to catalytically impaired, but conformationally active B-RAF oncogenic mutants, we discuss the possibility that KSR represents a natural allosteric inducer of RAF catalytic function.
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Affiliation(s)
- Mélanie Douziech
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Montréal, Quebec, Canada
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41
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Kutz SM, Higgins CE, Samarakoon R, Higgins SP, Allen RR, Qi L, Higgins PJ. TGF-beta 1-induced PAI-1 expression is E box/USF-dependent and requires EGFR signaling. Exp Cell Res 2006; 312:1093-105. [PMID: 16457817 DOI: 10.1016/j.yexcr.2005.12.027] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 01/06/2023]
Abstract
Transforming growth factor-beta1 (TGF-beta1) transcriptionally regulates the expression of genes that encode specific proteins (e.g., plasminogen activator inhibitor-1; PAI-1) important in stromal remodeling and cellular invasion. Definition of molecular events underlying TGF-beta1-initiated PAI-1 transcription, therefore, may lead to the identification of new therapeutic targets for diseases associated with elevated PAI-1 synthesis (e.g., tissue fibrosis, vascular disorders, tumor progression). An intact upstream stimulatory factor (USF)-binding E box motif (5'-(-165)CACGTG(-160)-3') at the HRE-2 site in the rat PAI-1 gene was required for PAI-1 transcription in TGF-beta1-treated cells. Mutation of the CA dinucleotide to TC at position -165/-164 in a reporter construct driven by 764 bp of PAI-1 promoter sequence decreased TGF-beta1-dependent CAT activity by >80% indicating the necessity for a consensus hexanucleotide E box motif in induced expression. The same CA --> TC substitution eliminated USF binding to an 18-bp HRE-2 DNA target highlighting the importance of site occupancy to transcriptional activation. Transfection of a dominant-negative USF construct, moreover, completely inhibited formation of USF/HRE-2 probe complexes, attenuated PAI-1 promoter-driven luciferase activity and reduced the response of the endogenous PAI-1 gene to TGF-beta1 (to that approximating quiescent controls). Maximal immediate-early PAI-1 induction upon exposure to TGF-beta1 required EGFR, p21ras, MEK and pp60(c-src) signaling as pharmacologic or dominant-negative inhibition of any of the four intermediates (EGFR, p21ras, MEK, pp60(c-src)) virtually eliminated TGF-beta1-augmented PAI-1 levels. U0126 titering experiments, furthermore, revealed that the same MEK inhibitor concentration that blocked the TGF-beta1 increase in ERK1/2 phosphorylation (20 microM) also effectively attenuated the PAI-1 inductive response suggesting a requirement for stimulated ERK signaling in TGF-beta1-mediated PAI-1 expression. These data suggest a model whereby TGF-beta1 activates a complex signaling cascade to affect PAI-1 gene control and involves USF occupancy of a critical E box motif at the HRE-2 site in the PAI-1 gene.
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Affiliation(s)
- Stacie M Kutz
- Center for Cell Biology and Cancer Research, Albany Medical College, MC-165, 47 New Scotland Avenue, Albany, NY 12208, USA
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42
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Kolch W. Coordinating ERK/MAPK signalling through scaffolds and inhibitors. Nat Rev Mol Cell Biol 2005; 6:827-37. [PMID: 16227978 DOI: 10.1038/nrm1743] [Citation(s) in RCA: 806] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The pathway from Ras through Raf and MEK (MAPK and ERK kinase) to ERK/MAPK (extracellular signal-regulated kinase/mitogen-activated protein kinase) regulates many fundamental cellular processes. Recently, a number of scaffolding proteins and endogenous inhibitors have been identified, and their important roles in regulating signalling through this pathway are now emerging. Some scaffolds augment the signal flux, but also mediate crosstalk with other pathways; certain adaptors target MEK-ERK/MAPK complexes to subcellular localizations; others provide regulated inhibition. Computational modelling indicates that, together, these modulators can determine the dynamic biological behaviour of the pathway.
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Affiliation(s)
- Walter Kolch
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.
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43
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Fritz RD, Radziwill G. The scaffold protein CNK1 interacts with the angiotensin II type 2 receptor. Biochem Biophys Res Commun 2005; 338:1906-12. [PMID: 16289034 DOI: 10.1016/j.bbrc.2005.10.168] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Accepted: 10/27/2005] [Indexed: 11/23/2022]
Abstract
The scaffold protein CNK1 mediates proliferative as well as antiproliferative responses including differentiation and apoptosis. The angiotensin II type 2 (AT2) receptor belongs to the class of G protein-coupled receptors and also promotes antiproliferative effects. Here we report that CNK1 binds through the sterile alpha motif (SAM) and the conserved region in CNK (CRIC) to the AT2 receptor. The exchange of a conserved leucine residue with arginine in the CRIC domain increases the binding affinity of CNK1 to the AT2 receptor. The insertion of a negatively charged amino acid stretch into the linker region between the N- and the C-terminal part of CNK1 strengthens the interaction between CNK1 and the AT2 receptor in a Ras-regulated manner. The biological significance of the interaction was supported by coprecipitation of CNK1 and the AT2 receptor in mouse heart extracts. Thus, CNK1 may play a role in the AT2 receptor-mediated signaling pathways.
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Affiliation(s)
- Rafael D Fritz
- Institute of Medical Virology, University of Zurich, 8006 Zurich, Switzerland
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