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Vasta JD, Michaud A, Zimprich CA, Beck MT, Swiatnicki MR, Zegzouti H, Thomas MR, Wilkinson J, Crapster JA, Robers MB. Protomer selectivity of type II RAF inhibitors within the RAS/RAF complex. Cell Chem Biol 2023; 30:1354-1365.e6. [PMID: 37643616 DOI: 10.1016/j.chembiol.2023.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/12/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023]
Abstract
RAF dimer inhibitors offer therapeutic potential in RAF- and RAS-driven cancers. The utility of such drugs is predicated on their capacity to occupy both RAF protomers in the RAS-RAF signaling complex. Here we describe a method to conditionally quantify drug-target occupancy at selected RAF protomers within an active RAS-RAF complex in cells. RAF target engagement can be measured in the presence or absence of any mutant KRAS allele, enabling the high-affinity state of RAF dimer inhibitors to be quantified in the cellular milieu. The intracellular protomer selectivity of clinical-stage type II RAF inhibitors revealed that ARAF protomer engagement, but not engagement of BRAF or CRAF, is commensurate with inhibition of MAPK signaling in various mutant RAS cell lines. Our results support a fundamental role for ARAF in mutant RAS signaling and reveal poor ARAF protomer vulnerability for a cohort of RAF inhibitors undergoing clinical evaluation.
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Su D, Zhu S, Hou Z, Hao F, Xu K, Xu F, Zhu Y, Liu D, Xu J, Tao J. Toxoplasma gondii infection regulates apoptosis of host cells via miR-185/ ARAF axis. Parasit Vectors 2023; 16:371. [PMID: 37858158 PMCID: PMC10585723 DOI: 10.1186/s13071-023-05991-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/29/2023] [Indexed: 10/21/2023] Open
Abstract
BACKGROUND Toxoplasmosis is a zoonosis with a worldwide presence that is caused by the intracellular parasite Toxoplasma gondii. Active regulation of apoptosis is an important immune mechanism by which host cells resist the growth of T. gondii or avoid excessive pathological damage induced by this parasite. Previous studies found that upregulated expression of microRNA-185 (miR-185) during T. gondii infection has a potential role in regulating the expression of the ARAF gene, which is reported to be associated with cell proliferation and apoptosis. METHODS The expression levels of miR-185 and the ARAF gene were evaluated by qPCR and Western blot, respectively, in mice tissues, porcine kidney epithelial cells (PK-15) and porcine alveolar macrophages (3D4/21) following infection with the T. gondii ToxoDB#9 and RH strains. The dual luciferase reporter assay was then used to verify the relationship between miR-185 and ARAF targets in PK-15 cells. PK-15 and 3D4/21 cell lines with stable knockout of the ARAF gene were established by CRISPR, and then the apoptosis rates of the cells following T. gondii infection were detected using cell flow cytometry assays. Simultaneously, the activities of cleaved caspase-3, as a key apoptosis executive protein, were detected by Western blot to evaluate the apoptosis levels of cells. RESULTS Infection with both the T. gondii ToxoDB#9 and RH strains induced an increased expression of miR-185 and a decreased expression of ARAF in mice tissues, PK-15 and 3D4/21 cells. MiR-185 mimic transfections showed a significantly negative correlation in expression levels between miR-185 and the ARAF gene. The dual luciferase reporter assay confirmed that ARAF was a target of miR-185. Functional investigation revealed that T. gondii infection induced the apoptosis of PK-15 and 3D4/21 cells, which could be inhibited by ARAF knockout or overexpression of miR-185. The expression levels of cleaved caspase-3 protein were significantly lower in cells with ARAF knockout than in normal cells, which were consistent with the results of the cell flow cytometry assays. CONCLUSIONS Toxoplasma gondii infection could lead to the upregulation of miR-185 and the downregulation of ARAF, which was not related to the strain of T. gondii and the host cells. Toxoplasma gondii infection could regulate the apoptosis of host cells via the miR-185/ARAF axis, which represents an additional strategy used by T. gondii to counteract host-cell apoptosis in order to maintain survival and reproduce in the host cells.
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Affiliation(s)
- Dingzeyang Su
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Shifan Zhu
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Zhaofeng Hou
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Fuxing Hao
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, 225300 People’s Republic of China
| | - Kangzhi Xu
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Fan Xu
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Yuyang Zhu
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Dandan Liu
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Jinjun Xu
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
| | - Jianping Tao
- College of Veterinary Medicine, Yangzhou University, 12 East Wenhui Road, Yangzhou, 225009 Jiangsu People’s Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, 225009 People’s Republic of China
- International Research Laboratory of Prevention and Control of Important Animal Infectious Diseases and Zoonotic Diseases of Jiangsu Higher Education Institutions, Yangzhou University, Yangzhou, 225009 People’s Republic of China
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3
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Lyon A, Tripathi R, Meeks C, He D, Wu Y, Liu J, Wang C, Chen J, Zhu H, Mukherjee S, Ganguly S, Plattner R. ABL1/2 and DDR1 Drive MEKi Resistance in NRAS-Mutant Melanomas by Stabilizing RAF/MYC/ETS1 and Promoting RAF Homodimerization. Cancers (Basel) 2023; 15:954. [PMID: 36765910 PMCID: PMC9913232 DOI: 10.3390/cancers15030954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/06/2023] [Accepted: 01/11/2023] [Indexed: 02/05/2023] Open
Abstract
Melanomas harboring NRAS mutations are a particularly aggressive and deadly subtype. If patients cannot tolerate or the melanomas are insensitive to immune checkpoint blockade, there are no effective 2nd-line treatment options. Drugs targeting the RAF/MEK/ERK pathway, which are used for BRAF-mutant melanomas, do little to increase progression-free survival (PFS). Here, using both loss-of-function and gain-of-function approaches, we show that ABL1/2 and DDR1 are critical nodes during NRAS-mutant melanoma intrinsic and acquired MEK inhibitor (MEKi) resistance. In some acquired resistance cells, ABL1/2 and DDR1 cooperate to stabilize RAF proteins, activate ERK cytoplasmic and nuclear signaling, repress p27/KIP1 expression, and drive RAF homodimerization. In contrast, other acquired resistance cells depend solely on ABL1/2 for their survival, and are sensitive to highly specific allosteric ABL1/2 inhibitors, which prevent β-catenin nuclear localization and destabilize MYC and ETS1 in an ERK-independent manner. Significantly, targeting ABL1/2 and DDR1 with an FDA-approved anti-leukemic drug, reverses intrinsic MEKi resistance, delays acquisition of acquired resistance, and doubles the survival time in a NRAS-mutant mouse model. These data indicate that repurposing FDA-approved drugs targeting ABL1/2 and DDR1 may be a novel and effective strategy for treating patients with treatment-refractory NRAS-driven melanomas.
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Affiliation(s)
- Anastasia Lyon
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Rakshamani Tripathi
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Christina Meeks
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Daheng He
- Biostatistics and Bioinformatics Shared Resource Facility, College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, KY 40508, USA
| | - Yuanyuan Wu
- Biostatistics and Bioinformatics Shared Resource Facility, College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, KY 40508, USA
| | - Jinpeng Liu
- Biostatistics and Bioinformatics Shared Resource Facility, College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, KY 40508, USA
| | - Chi Wang
- Biostatistics and Bioinformatics Shared Resource Facility, College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, KY 40508, USA
| | - Jing Chen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Sujata Mukherjee
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Saptadwipa Ganguly
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Rina Plattner
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
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4
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Su W, Mukherjee R, Yaeger R, Son J, Xu J, Na N, Merna Timaul N, Hechtman J, Paroder V, Lin M, Mattar M, Qiu J, Chang Q, Zhao H, Zhang J, Little M, Adachi Y, Han SW, Taylor BS, Ebi H, Abdel-Wahab O, de Stanchina E, Rudin CM, Jänne PA, McCormick F, Yao Z, Rosen N. ARAF protein kinase activates RAS by antagonizing its binding to RASGAP NF1. Mol Cell 2022:S1097-2765(22)00434-8. [PMID: 35613620 DOI: 10.1016/j.molcel.2022.04.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 03/02/2022] [Accepted: 04/26/2022] [Indexed: 12/13/2022]
Abstract
RAF protein kinases are effectors of the GTP-bound form of small guanosine triphosphatase RAS and function by phosphorylating MEK. We showed here that the expression of ARAF activated RAS in a kinase-independent manner. Binding of ARAF to RAS displaced the GTPase-activating protein NF1 and antagonized NF1-mediated inhibition of RAS. This reduced ERK-dependent inhibition of RAS and increased RAS-GTP. By this mechanism, ARAF regulated the duration and consequences of RTK-induced RAS activation and supported the RAS output of RTK-dependent tumor cells. In human lung cancers with EGFR mutation, amplification of ARAF was associated with acquired resistance to EGFR inhibitors, which was overcome by combining EGFR inhibitors with an inhibitor of the protein tyrosine phosphatase SHP2 to enhance inhibition of nucleotide exchange and RAS activation.
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5
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Venkatanarayan A, Liang J, Yen I, Shanahan F, Haley B, Phu L, Verschueren E, Hinkle TB, Kan D, Segal E, Long JE, Lima T, Liau NPD, Sudhamsu J, Li J, Klijn C, Piskol R, Junttila MR, Shaw AS, Merchant M, Chang MT, Kirkpatrick DS, Malek S. CRAF dimerization with ARAF regulates KRAS-driven tumor growth. Cell Rep 2022; 38:110351. [PMID: 35139374 DOI: 10.1016/j.celrep.2022.110351] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 09/21/2021] [Accepted: 01/19/2022] [Indexed: 02/07/2023] Open
Abstract
KRAS, which is mutated in ∼30% of all cancers, activates the RAF-MEK-ERK signaling cascade. CRAF is required for growth of KRAS mutant lung tumors, but the requirement for CRAF kinase activity is unknown. Here, we show that subsets of KRAS mutant tumors are dependent on CRAF for growth. Kinase-dead but not dimer-defective CRAF rescues growth inhibition, suggesting that dimerization but not kinase activity is required. Quantitative proteomics demonstrates increased levels of CRAF:ARAF dimers in KRAS mutant cells, and depletion of both CRAF and ARAF rescues the CRAF-loss phenotype. Mechanistically, CRAF depletion causes sustained ERK activation and induction of cell-cycle arrest, while treatment with low-dose MEK or ERK inhibitor rescues the CRAF-loss phenotype. Our studies highlight the role of CRAF in regulating MAPK signal intensity to promote tumorigenesis downstream of mutant KRAS and suggest that disrupting CRAF dimerization or degrading CRAF may have therapeutic benefit.
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Affiliation(s)
| | - Jason Liang
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA; Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Ivana Yen
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Frances Shanahan
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Benjamin Haley
- Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Lilian Phu
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Erik Verschueren
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Trent B Hinkle
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - David Kan
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Ehud Segal
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jason E Long
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Tony Lima
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Nicholas P D Liau
- Department of Structural Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jawahar Sudhamsu
- Department of Structural Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jason Li
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Christiaan Klijn
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Robert Piskol
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Melissa R Junttila
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Andrey S Shaw
- Department of Research Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Mark Merchant
- Department of Translational Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Matthew T Chang
- Department of Bioinformatics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Donald S Kirkpatrick
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Shiva Malek
- Department of Discovery Oncology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
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6
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Abstract
Kinases form the major part of the druggable genome and their selective inhibition in human cancers has had reasonable clinical success. In contrast to tumorigenesis, the role of kinases in mediating immune responses is poorly understood. However, synergistic therapeutic regimens combining targeted therapy and immune therapy have been found to increase the median survival of tumor patients. In this context, we uncovered that RAF and MEK1/2 kinases, which are the integral parts of the classical MAPK cascade, have unique roles in driving DC differentiation and activation. RAF kinases are stabilized in their protein levels during DC differentiation and are obligatory for normal functioning of DCs. But, the targeting of MEK1/2 kinases with specific inhibitors did not phenocopy the effects observed with RAF inhibitors suggesting that RAF and MEK1/2 kinases may have specific and unique roles in driving immune responses, which deserves further studies to successfully administer these inhibitors in clinics.
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Affiliation(s)
- Kristina Riegel
- Cell Biology Unit, University Medical Center Mainz, JGU-Mainz , Mainz, Germany
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7
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Hwang HW, Saito Y, Park CY, Blachère NE, Tajima Y, Fak JJ, Zucker-Scharff I, Darnell RB. cTag-PAPERCLIP Reveals Alternative Polyadenylation Promotes Cell-Type Specific Protein Diversity and Shifts Araf Isoforms with Microglia Activation. Neuron 2017; 95:1334-1349.e5. [PMID: 28910620 DOI: 10.1016/j.neuron.2017.08.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 07/07/2017] [Accepted: 08/11/2017] [Indexed: 12/23/2022]
Abstract
Alternative polyadenylation (APA) is increasingly recognized to regulate gene expression across different cell types, but obtaining APA maps from individual cell types typically requires prior purification, a stressful procedure that can itself alter cellular states. Here, we describe a new platform, cTag-PAPERCLIP, that generates APA profiles from single cell populations in intact tissues; cTag-PAPERCLIP requires no tissue dissociation and preserves transcripts in native states. Applying cTag-PAPERCLIP to profile four major cell types in the mouse brain revealed common APA preferences between excitatory and inhibitory neurons distinct from astrocytes and microglia, regulated in part by neuron-specific RNA-binding proteins NOVA2 and PTBP2. We further identified a role of APA in switching Araf protein isoforms during microglia activation, impacting production of downstream inflammatory cytokines. Our results demonstrate the broad applicability of cTag-PAPERCLIP and a previously undiscovered role of APA in contributing to protein diversity between different cell types and cellular states within the brain.
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Affiliation(s)
- Hun-Way Hwang
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA; Department of Pathology, University of Pittsburgh, School of Medicine, 3550 Terrace Street, Pittsburgh, PA 15213, USA.
| | - Yuhki Saito
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Christopher Y Park
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA; New York Genome Center, 101 Avenue of the Americas, New York, NY 10013, USA
| | - Nathalie E Blachère
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Yoko Tajima
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - John J Fak
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Ilana Zucker-Scharff
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Robert B Darnell
- Laboratory of Molecular Neuro-Oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA; New York Genome Center, 101 Avenue of the Americas, New York, NY 10013, USA.
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8
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Abstract
Using mouse genetics, we recently showed that BRAF has a critical role in initiation of NRAS-driven melanoma that cannot be compensated by CRAF. In contrast, RAF proteins display compensatory functions in fully established tumors and ARAF can sustain proliferation in the absence of BRAF and CRAF, highlighting an addiction to RAF signaling in NRAS-driven melanoma.
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Affiliation(s)
- Sabine Druillennec
- Institut Curie, Orsay, France.,INSERM U1021, Centre Universitaire, Orsay, France.,CNRS UMR 3347, Centre Universitaire, Orsay, France.,Université Paris Sud-11, Orsay, France.,Equipe Labellisée Ligue Nationale Contre le Cancer
| | - Celio Pouponnot
- Institut Curie, Orsay, France.,INSERM U1021, Centre Universitaire, Orsay, France.,CNRS UMR 3347, Centre Universitaire, Orsay, France.,Université Paris Sud-11, Orsay, France.,Equipe Labellisée Ligue Nationale Contre le Cancer
| | - Alain Eychène
- Institut Curie, Orsay, France.,INSERM U1021, Centre Universitaire, Orsay, France.,CNRS UMR 3347, Centre Universitaire, Orsay, France.,Université Paris Sud-11, Orsay, France.,Equipe Labellisée Ligue Nationale Contre le Cancer
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9
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Abstract
Histiocytic disorders represent clonal disorders of cells believed to be derived from the monocyte, macrophage, and/or dendritic cell lineage presenting with a range of manifestations. Although their nature as clonal versus inflammatory nonclonal conditions have long been debated, recent studies identified numerous somatic mutations that activate mitogen-activated protein kinase signaling in clinically and histologically diverse forms of histiocytosis. Clinical trials and case series have revealed that targeting aberrant kinase signaling using BRAF and/or MEK inhibitors may be effective. These findings suggest that a personalized approach in which patient-specific alterations are identified and targeted may be a critically important therapeutic approach.
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Affiliation(s)
- Neval Ozkaya
- Department of Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Ahmet Dogan
- Department of Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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10
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Abstract
The RAF-MAPK signaling pathway regulates several very diverse cellular processes such as proliferation, differentiation, apoptosis, and transformation. While the canonical function of RAF kinases within the MAPK pathway is the activation of MEK, our group could demonstrate an important crosstalk between RAF signaling and the pro-apoptotic mammalian sterile 20-like kinase (MST2) tumor suppressor pathway in several cancer entities, including head and neck, colon, and breast. Here, the RAF kinases CRAF and ARAF sequester and inhibit the pro-apoptotic kinase MST2 independently of their own kinase activity. In our recent study, we showed that the ARAF-MST2 complex is regulated by subcellular compartmentalization during epithelial differentiation. Proliferating cells of the basal cell layer in squamous epithelia and tumor cells express ARAF at the mitochondria thus allowing for efficient sequestration of MST2. In contrast, non-malignant squamous epithelia have ARAF localized at the plasma membrane, where the control of MST2-mediated apoptosis is compromised. This re-distribution is regulated by the scaffold protein kinase suppressor of Ras 2 (KSR2). Here, we summarize how spatial and temporal regulation of RAF signaling complexes affect cellular signaling and functions.
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Affiliation(s)
- Jens Rauch
- a Systems Biology Ireland, University College Dublin , Ireland
| | - Walter Kolch
- a Systems Biology Ireland, University College Dublin , Ireland.,b School of Medicine and Medical Science, University College Dublin , Belfield, Dublin , Ireland
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