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Iyer KS, Prabhakara C, Mayor S, Rao M. Cellular compartmentalisation and receptor promiscuity as a strategy for accurate and robust inference of position during morphogenesis. eLife 2023; 12:79257. [PMID: 36877545 PMCID: PMC9988261 DOI: 10.7554/elife.79257] [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: 04/05/2022] [Accepted: 01/14/2023] [Indexed: 03/07/2023] Open
Abstract
Precise spatial patterning of cell fate during morphogenesis requires accurate inference of cellular position. In making such inferences from morphogen profiles, cells must contend with inherent stochasticity in morphogen production, transport, sensing and signalling. Motivated by the multitude of signalling mechanisms in various developmental contexts, we show how cells may utilise multiple tiers of processing (compartmentalisation) and parallel branches (multiple receptor types), together with feedback control, to bring about fidelity in morphogenetic decoding of their positions within a developing tissue. By simultaneously deploying specific and nonspecific receptors, cells achieve a more accurate and robust inference. We explore these ideas in the patterning of Drosophila melanogaster wing imaginal disc by Wingless morphogen signalling, where multiple endocytic pathways participate in decoding the morphogen gradient. The geometry of the inference landscape in the high dimensional space of parameters provides a measure for robustness and delineates stiff and sloppy directions. This distributed information processing at the scale of the cell highlights how local cell autonomous control facilitates global tissue scale design.
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Affiliation(s)
- Krishnan S Iyer
- Simons Center for the Study of Living Machines, National Center for Biological Sciences - TIFRBangaloreIndia
| | | | - Satyajit Mayor
- National Center for Biological Sciences - TIFRBangaloreIndia
| | - Madan Rao
- Simons Center for the Study of Living Machines, National Center for Biological Sciences - TIFRBangaloreIndia
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2
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Pudewell S, Wittich C, Kazemein Jasemi NS, Bazgir F, Ahmadian MR. Accessory proteins of the RAS-MAPK pathway: moving from the side line to the front line. Commun Biol 2021; 4:696. [PMID: 34103645 PMCID: PMC8187363 DOI: 10.1038/s42003-021-02149-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/23/2021] [Indexed: 02/07/2023] Open
Abstract
Health and disease are directly related to the RTK-RAS-MAPK signalling cascade. After more than three decades of intensive research, understanding its spatiotemporal features is afflicted with major conceptual shortcomings. Here we consider how the compilation of a vast array of accessory proteins may resolve some parts of the puzzles in this field, as they safeguard the strength, efficiency and specificity of signal transduction. Targeting such modulators, rather than the constituent components of the RTK-RAS-MAPK signalling cascade may attenuate rather than inhibit disease-relevant signalling pathways.
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Affiliation(s)
- Silke Pudewell
- grid.411327.20000 0001 2176 9917Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Christoph Wittich
- grid.411327.20000 0001 2176 9917Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Neda S. Kazemein Jasemi
- grid.411327.20000 0001 2176 9917Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Farhad Bazgir
- grid.411327.20000 0001 2176 9917Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Mohammad R. Ahmadian
- grid.411327.20000 0001 2176 9917Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
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3
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Natural Products Attenuating Biosynthesis, Processing, and Activity of Ras Oncoproteins: State of the Art and Future Perspectives. Biomolecules 2020; 10:biom10111535. [PMID: 33182807 PMCID: PMC7698260 DOI: 10.3390/biom10111535] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/08/2020] [Indexed: 02/07/2023] Open
Abstract
RAS genes encode signaling proteins, which, in mammalian cells, act as molecular switches regulating critical cellular processes as proliferation, growth, differentiation, survival, motility, and metabolism in response to specific stimuli. Deregulation of Ras functions has a high impact on human health: gain-of-function point mutations in RAS genes are found in some developmental disorders and thirty percent of all human cancers, including the deadliest. For this reason, the pathogenic Ras variants represent important clinical targets against which to develop novel, effective, and possibly selective pharmacological inhibitors. Natural products represent a virtually unlimited resource of structurally different compounds from which one could draw on for this purpose, given the improvements in isolation and screening of active molecules from complex sources. After a summary of Ras proteins molecular and regulatory features and Ras-dependent pathways relevant for drug development, we point out the most promising inhibitory approaches, the known druggable sites of wild-type and oncogenic Ras mutants, and describe the known natural compounds capable of attenuating Ras signaling. Finally, we highlight critical issues and perspectives for the future selection of potential Ras inhibitors from natural sources.
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4
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Shimell JJ, Shah BS, Cain SM, Thouta S, Kuhlmann N, Tatarnikov I, Jovellar DB, Brigidi GS, Kass J, Milnerwood AJ, Snutch TP, Bamji SX. The X-Linked Intellectual Disability Gene Zdhhc9 Is Essential for Dendrite Outgrowth and Inhibitory Synapse Formation. Cell Rep 2020; 29:2422-2437.e8. [PMID: 31747610 DOI: 10.1016/j.celrep.2019.10.065] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/09/2019] [Accepted: 10/13/2019] [Indexed: 11/29/2022] Open
Abstract
Palmitoylation is a reversible post-translational lipid modification that facilitates vesicular transport and subcellular localization of modified proteins. This process is catalyzed by ZDHHC enzymes that are implicated in several neurological and neurodevelopmental disorders. Loss-of-function mutations in ZDHHC9 have been identified in patients with X-linked intellectual disability (XLID) and associated with increased epilepsy risk. Loss of Zdhhc9 function in hippocampal cultures leads to shorter dendritic arbors and fewer inhibitory synapses, altering the ratio of excitatory-to-inhibitory inputs formed onto Zdhhc9-deficient cells. While Zdhhc9 promotes dendrite outgrowth through the palmitoylation of the GTPase Ras, it promotes inhibitory synapse formation through the palmitoylation of another GTPase, TC10. Zdhhc9 knockout mice exhibit seizure-like activity together with increased frequency and amplitude of both spontaneous and miniature excitatory and inhibitory postsynaptic currents. These findings present a plausible mechanism for how the loss of ZDHHC9 function may contribute to XLID and epilepsy.
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Affiliation(s)
- Jordan J Shimell
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Bhavin S Shah
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Stuart M Cain
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Samrat Thouta
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Naila Kuhlmann
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - Igor Tatarnikov
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - D Blair Jovellar
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - G Stefano Brigidi
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Jennifer Kass
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Austen J Milnerwood
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada
| | - Shernaz X Bamji
- Department of Cellular and Physiological Sciences, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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Pleiotropic Roles of Calmodulin in the Regulation of KRas and Rac1 GTPases: Functional Diversity in Health and Disease. Int J Mol Sci 2020; 21:ijms21103680. [PMID: 32456244 PMCID: PMC7279331 DOI: 10.3390/ijms21103680] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/18/2020] [Accepted: 05/21/2020] [Indexed: 12/21/2022] Open
Abstract
Calmodulin is a ubiquitous signalling protein that controls many biological processes due to its capacity to interact and/or regulate a large number of cellular proteins and pathways, mostly in a Ca2+-dependent manner. This complex interactome of calmodulin can have pleiotropic molecular consequences, which over the years has made it often difficult to clearly define the contribution of calmodulin in the signal output of specific pathways and overall biological response. Most relevant for this review, the ability of calmodulin to influence the spatiotemporal signalling of several small GTPases, in particular KRas and Rac1, can modulate fundamental biological outcomes such as proliferation and migration. First, direct interaction of calmodulin with these GTPases can alter their subcellular localization and activation state, induce post-translational modifications as well as their ability to interact with effectors. Second, through interaction with a set of calmodulin binding proteins (CaMBPs), calmodulin can control the capacity of several guanine nucleotide exchange factors (GEFs) to promote the switch of inactive KRas and Rac1 to an active conformation. Moreover, Rac1 is also an effector of KRas and both proteins are interconnected as highlighted by the requirement for Rac1 activation in KRas-driven tumourigenesis. In this review, we attempt to summarize the multiple layers how calmodulin can regulate KRas and Rac1 GTPases in a variety of cellular events, with biological consequences and potential for therapeutic opportunities in disease settings, such as cancer.
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Konstantinidou G, Rimessi A. Editorial: Oncogenic RAS-Dependent Reprogramming of Cellular Plasticity. Front Oncol 2020; 10:588. [PMID: 32391272 PMCID: PMC7188944 DOI: 10.3389/fonc.2020.00588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 03/31/2020] [Indexed: 12/12/2022] Open
Affiliation(s)
| | - Alessandro Rimessi
- Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
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7
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Small GTPase peripheral binding to membranes: molecular determinants and supramolecular organization. Biochem Soc Trans 2018; 47:13-22. [PMID: 30559268 DOI: 10.1042/bst20170525] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 11/23/2018] [Accepted: 11/27/2018] [Indexed: 01/26/2023]
Abstract
Small GTPases regulate many aspects of cell logistics by alternating between an inactive, GDP-bound form and an active, GTP-bound form. This nucleotide switch is coupled to a cytosol/membrane cycle, such that GTP-bound small GTPases carry out their functions at the periphery of endomembranes. A global understanding of the molecular determinants of the interaction of small GTPases with membranes and of the resulting supramolecular organization is beginning to emerge from studies of model systems. Recent studies highlighted that small GTPases establish multiple interactions with membranes involving their lipid anchor, their lipididated hypervariable region and elements in their GTPase domain, which combine to determine the strength, specificity and orientation of their association with lipids. Thereby, membrane association potentiates small GTPase interactions with GEFs, GAPs and effectors through colocalization and positional matching. Furthermore, it leads to small GTPase nanoclustering and to lipid demixing, which drives the assembly of molecular platforms in which proteins and lipids co-operate in producing high-fidelity signals through feedback and feedforward loops. Although still fragmentary, these observations point to an integrated model of signaling by membrane-attached small GTPases that involves a diversity of direct and indirect interactions, which can inspire new therapeutic strategies to block their activities in diseases.
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8
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Bratt JM, Chang KY, Rabowsky M, Franzi LM, Ott SP, Filosto S, Goldkorn T, Arif M, Last JA, Kenyon NJ, Zeki AA. Farnesyltransferase Inhibition Exacerbates Eosinophilic Inflammation and Airway Hyperreactivity in Mice with Experimental Asthma: The Complex Roles of Ras GTPase and Farnesylpyrophosphate in Type 2 Allergic Inflammation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2018; 200:3840-3856. [PMID: 29703864 PMCID: PMC5964018 DOI: 10.4049/jimmunol.1601317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 03/14/2018] [Indexed: 12/13/2022]
Abstract
Ras, a small GTPase protein, is thought to mediate Th2-dependent eosinophilic inflammation in asthma. Ras requires cell membrane association for its biological activity, and this requires the posttranslational modification of Ras with an isoprenyl group by farnesyltransferase (FTase) or geranylgeranyltransferase (GGTase). We hypothesized that inhibition of FTase using FTase inhibitor (FTI)-277 would attenuate allergic asthma by depleting membrane-associated Ras. We used the OVA mouse model of allergic inflammation and human airway epithelial (HBE1) cells to determine the role of FTase in inflammatory cell recruitment. BALB/c mice were first sensitized then exposed to 1% OVA aerosol or filtered air, and half were injected daily with FTI-277 (20 mg/kg per day). Treatment of mice with FTI-277 had no significant effect on lung membrane-anchored Ras, Ras protein levels, or Ras GTPase activity. In OVA-exposed mice, FTI-277 treatment increased eosinophilic inflammation, goblet cell hyperplasia, and airway hyperreactivity. Human bronchial epithelial (HBE1) cells were pretreated with 5, 10, or 20 μM FTI-277 prior to and during 12 h IL-13 (20 ng/ml) stimulation. In HBE1 cells, FTase inhibition with FTI-277 had no significant effect on IL-13-induced STAT6 phosphorylation, eotaxin-3 peptide secretion, or Ras translocation. However, addition of exogenous FPP unexpectedly augmented IL-13-induced STAT6 phosphorylation and eotaxin-3 secretion from HBE1 cells without affecting Ras translocation. Pharmacological inhibition of FTase exacerbates allergic asthma, suggesting a protective role for FTase or possibly Ras farnesylation. FPP synergistically augments epithelial eotaxin-3 secretion, indicating a novel Ras-independent farnesylation mechanism or direct FPP effect that promotes epithelial eotaxin-3 production in allergic asthma.
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Affiliation(s)
- Jennifer M Bratt
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
| | - Kevin Y Chang
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
| | - Michelle Rabowsky
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
| | - Lisa M Franzi
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
| | - Sean P Ott
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
| | - Simone Filosto
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
- Department of Internal Medicine, Respiratory Signal Transduction, Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA 95616
| | - Tzipora Goldkorn
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
- Department of Internal Medicine, Respiratory Signal Transduction, Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA 95616
| | - Muhammad Arif
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
| | - Jerold A Last
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
| | - Nicholas J Kenyon
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
| | - Amir A Zeki
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA 95817;
- Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California, Davis, Davis, CA 95817; and
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9
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Iommelli F, De Rosa V, Terlizzi C, Monti M, Panico M, Fonti R, Del Vecchio S. Inositol Trisphosphate Receptor Type 3-mediated Enhancement of EGFR and MET Cotargeting Efficacy in Non-Small Cell Lung Cancer Detected by 18F-fluorothymidine. Clin Cancer Res 2018; 24:3126-3136. [PMID: 29618618 DOI: 10.1158/1078-0432.ccr-17-3657] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/06/2018] [Accepted: 03/23/2018] [Indexed: 11/16/2022]
Abstract
Purpose: Our aim was to test whether imaging with 18F-fluorothymidine (18F-FLT) PET/CT was able to detect the combined effects of EGFR and MET inhibitors in oncogene-driven non-small cell lung cancer (NSCLC) and to elucidate the mechanisms underlying the enhanced efficacy of drug combination.Experimental Design: NSCLC cells bearing MET amplification (H1993 and H820) were treated with EGFR and MET inhibitors either alone or in combination and then tested for cell viability and inhibition of signaling. Nude mice bearing H1993 tumors underwent 18F-FLT PET/CT scan before and after treatment with erlotinib and crizotinib alone or in combination (1:1 ratio) and posttreatment changes of 18F-FLT uptake in tumors were determined. The role of inositol trisphosphate receptor type 3 (IP3R3) in mediating the combined action of EGFR and MET inhibitors was tested by transfecting NSCLC cells with IP3R3-targeted siRNA.Results: Imaging studies showed a significant reduction of 18F-FLT uptake in response to combined treatment with EGFR and MET inhibitors that was higher than that obtained with single agents (ANOVA, F-ratio = 6.215, P = 0.001). Imaging findings were confirmed by analysis of surgically excised tumors. Levels of IP3R3 were significantly reduced in both cells and tumors after treatment with crizotinib, whereas EGFR inhibitors caused a reduction of IP3R3 interaction with K-Ras mainly through dephosphorylation of serine residues of K-Ras.Conclusions: Our findings indicate that 18F-FLT PET/CT is able to detect the enhanced efficacy of EGFR and MET inhibitors in oncogene-driven NSCLC and that such enhancement is mediated by IP3R3 through its interaction with K-Ras. Clin Cancer Res; 24(13); 3126-36. ©2018 AACR.
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Affiliation(s)
- Francesca Iommelli
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy.,CEINGE-Advanced Biotechnologies, Naples Italy
| | - Viviana De Rosa
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy.,CEINGE-Advanced Biotechnologies, Naples Italy
| | - Cristina Terlizzi
- Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
| | - Marcello Monti
- Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
| | - Mariarosaria Panico
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Rosa Fonti
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Silvana Del Vecchio
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy. .,Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
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10
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Nakhaei-Rad S, Haghighi F, Nouri P, Rezaei Adariani S, Lissy J, Kazemein Jasemi NS, Dvorsky R, Ahmadian MR. Structural fingerprints, interactions, and signaling networks of RAS family proteins beyond RAS isoforms. Crit Rev Biochem Mol Biol 2018; 53:130-156. [PMID: 29457927 DOI: 10.1080/10409238.2018.1431605] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Saeideh Nakhaei-Rad
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Fereshteh Haghighi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Parivash Nouri
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Soheila Rezaei Adariani
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Jana Lissy
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Neda S Kazemein Jasemi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Radovan Dvorsky
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Mohammad Reza Ahmadian
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
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11
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Lu SM, Fairn GD. Mesoscale organization of domains in the plasma membrane - beyond the lipid raft. Crit Rev Biochem Mol Biol 2018; 53:192-207. [PMID: 29457544 DOI: 10.1080/10409238.2018.1436515] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The plasma membrane is compartmentalized into several distinct regions or domains, which show a broad diversity in both size and lifetime. The segregation of lipids and membrane proteins is thought to be driven by the lipid composition itself, lipid-protein interactions and diffusional barriers. With regards to the lipid composition, the immiscibility of certain classes of lipids underlies the "lipid raft" concept of plasmalemmal compartmentalization. Historically, lipid rafts have been described as cholesterol and (glyco)sphingolipid-rich regions of the plasma membrane that exist as a liquid-ordered phase that are resistant to extraction with non-ionic detergents. Over the years the interest in lipid rafts grew as did the challenges with studying these nanodomains. The term lipid raft has fallen out of favor with many scientists and instead the terms "membrane raft" or "membrane nanodomain" are preferred as they connote the heterogeneity and dynamic nature of the lipid-protein assemblies. In this article, we will discuss the classical lipid raft hypothesis and its limitations. This review will also discuss alternative models of lipid-protein interactions, annular lipid shells, and larger membrane clusters. We will also discuss the mesoscale organization of plasmalemmal domains including visible structures such as clathrin-coated pits and caveolae.
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Affiliation(s)
- Stella M Lu
- a Keenan Research Centre for Biomedical Science, St. Michael's Hospital , Toronto , Canada.,b Department of Biochemistry , University of Toronto , Toronto , Canada
| | - Gregory D Fairn
- a Keenan Research Centre for Biomedical Science, St. Michael's Hospital , Toronto , Canada.,b Department of Biochemistry , University of Toronto , Toronto , Canada.,c Department of Surgery , University of Toronto , Toronto , Canada
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12
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Mishra AR, Chaturvedi A. B Cell Receptor Signaling and Compartmentalization by Confocal Microscopy. Methods Mol Biol 2018; 1707:121-129. [PMID: 29388104 DOI: 10.1007/978-1-4939-7474-0_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Binding of antigen to the B cell receptor (BCR) triggers both BCR signaling and endocytosis simultaneously. BCR signaling pathways and their regulation have been studied extensively by both biochemical methods and flow cytometry, resulting in a comprehensive understanding of the temporal dynamics of the signaling enzymes and effector proteins. However, spatial regulation of these signaling pathways in subcellular pathways is relatively poorly understood. Here, we describe a method to study the spatio-temporal distribution of phosphorylated-kinases in antigen-activated B cells by confocal microscopy. This method can also be applied to other cell types where it is of interest to understand the spatial distribution of signaling enzymes and their effector proteins.
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Affiliation(s)
- Anurag R Mishra
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Indore, India
| | - Akanksha Chaturvedi
- Department of Biology, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra, India.
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13
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Chen GA, Lin YR, Chung HT, Hwang LH. H-Ras Exerts Opposing Effects on Type I Interferon Responses Depending on Its Activation Status. Front Immunol 2017; 8:972. [PMID: 28848563 PMCID: PMC5554495 DOI: 10.3389/fimmu.2017.00972] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/31/2017] [Indexed: 12/25/2022] Open
Abstract
Using shRNA high-throughput screening, we identified H-Ras as a regulator of antiviral activity, whose depletion could enhance Sindbis virus replication. Further analyses indicated that depletion of H-Ras results in a robust increase in vesicular stomatitis virus infection and a decrease in Sendai virus (SeV)-induced retinoic acid-inducible gene-I-like receptor (RLR) signaling. Interestingly, however, ectopic expression of wild-type H-Ras results in a biphasic mode of RLR signaling regulation: while low-level expression of H-Ras enhances SeV-induced RLR signaling, high-level expression of H-Ras significantly inhibits this signaling. The inhibitory effects correlate with the activation status of H-Ras. As a result, oncogenic H-Ras, H-RasV12, strongly inhibits SeV-induced IFN-β promoter activity and type I interferon signaling. Conversely, the positive effects exerted by H-Ras on RLR signaling are independent of its signaling activity, as a constitutively inactive form of H-Ras, H-RasN17, also positively regulates RLR signaling. Mechanistically, we demonstrate that depletion of H-Ras reduces the formation of MAVS–TNF receptor-associated factor 3 signaling complexes. These results reveal that the H-Ras protein plays a role in promoting MAVS signalosome assembly in the mitochondria, whereas oncogenic H-Ras exerts a negative effect on type I IFN responses.
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Affiliation(s)
- Guann-An Chen
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Yun-Ru Lin
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Hai-Ting Chung
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Lih-Hwa Hwang
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
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14
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Hennessey RC, Holderbaum AM, Bonilla A, Delaney C, Gillahan JE, Tober KL, Oberyszyn TM, Zippin JH, Burd CE. Ultraviolet radiation accelerates NRas-mutant melanomagenesis: A cooperative effect blocked by sunscreen. Pigment Cell Melanoma Res 2017; 30:477-487. [PMID: 28544727 DOI: 10.1111/pcmr.12601] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 05/17/2017] [Indexed: 11/28/2022]
Abstract
To mitigate melanoma risk, sunscreen use is widely advocated; yet, the ability of sunscreens to prevent melanoma remains controversial. Here, we test the tenet that sunscreens limit melanoma risk by blocking ultraviolet radiation (UV)-induced DNA damage using murine models that recapitulate the genetics and spontaneous evolution of human melanoma. We find that a single, non-erythematous dose of UV dramatically accelerates melanoma onset and increases tumor multiplicity in mice carrying an endogenous, melanocyte-specific NRas61R allele. By contrast, transient UV exposure does not alter tumor onset in mice lacking p16INK4a or harboring an NRas12D allele. To block the rapid onset of melanoma cooperatively caused by UV and NRas61R , we employed a variety of aerosol sunscreens. While all sunscreens delayed melanoma formation and blocked UV-induced DNA damage, differences in aerosol output (i.e., amount applied/cm2 ) caused variability in the cancer preventative efficacy of products with identical sunburn protection factor (SPF) ratings.
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Affiliation(s)
- Rebecca C Hennessey
- Department of Cancer Biology and Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
| | - Andrea M Holderbaum
- Department of Cancer Biology and Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA.,Department of Molecular Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
| | - Anamaria Bonilla
- Department of Cancer Biology and Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA.,Department of Molecular Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
| | - Conor Delaney
- Department of Cancer Biology and Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
| | - James E Gillahan
- Department of Cancer Biology and Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
| | - Kathleen L Tober
- Department of Pathology, The Ohio State University, Columbus, OH, USA
| | | | - Jonathan H Zippin
- Department of Dermatology, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY, USA
| | - Christin E Burd
- Department of Cancer Biology and Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA.,Department of Molecular Genetics, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
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15
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Sperlich B, Kapoor S, Waldmann H, Winter R, Weise K. Regulation of K-Ras4B Membrane Binding by Calmodulin. Biophys J 2017; 111:113-22. [PMID: 27410739 DOI: 10.1016/j.bpj.2016.05.042] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/03/2016] [Accepted: 05/24/2016] [Indexed: 12/28/2022] Open
Abstract
K-Ras4B is a membrane-bound small GTPase with a prominent role in cancer development. It contains a polybasic farnesylated C-terminus that is required for the correct localization and clustering of K-Ras4B in distinct membrane domains. PDEδ and the Ca(2+)-binding protein calmodulin (CaM) are known to function as potential binding partners for farnesylated Ras proteins. However, they differ in the number of interaction sites with K-Ras4B, leading to different modes of interaction, and thus affect the subcellular distribution of K-Ras4B in different ways. Although it is clear that Ca(2+)-bound CaM can play a role in the dynamic spatial cycle of K-Ras4B in the cell, the exact molecular mechanism is only partially understood. In this biophysical study, we investigated the effect of Ca(2+)/CaM on the interaction of GDP- and GTP-loaded K-Ras4B with heterogeneous model biomembranes by using a combination of different spectroscopic and imaging techniques. The results show that Ca(2+)/CaM is able to extract K-Ras4B from negatively charged membranes in a nucleotide-independent manner. Moreover, the data demonstrate that the complex of Ca(2+)/CaM and K-Ras4B is stable in the presence of anionic membranes and shows no membrane binding. Finally, the influence of Ca(2+)/CaM on the interaction of K-Ras4B with membranes is compared with that of PDEδ, which was investigated in a previous study. Although both CaM and PDEδ exhibit a hydrophobic binding pocket for farnesyl, they have different effects on membrane binding of K-Ras4B and hence should be capable of regulating K-Ras4B plasma membrane localization in the cell.
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Affiliation(s)
- Benjamin Sperlich
- Physical Chemistry I - Biophysical Chemistry, TU Dortmund University, Dortmund, Germany
| | - Shobhna Kapoor
- Chemical Biology, TU Dortmund University, Dortmund, Germany; Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Herbert Waldmann
- Chemical Biology, TU Dortmund University, Dortmund, Germany; Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Roland Winter
- Physical Chemistry I - Biophysical Chemistry, TU Dortmund University, Dortmund, Germany.
| | - Katrin Weise
- Physical Chemistry I - Biophysical Chemistry, TU Dortmund University, Dortmund, Germany.
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16
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Zhao B, Hu W, Kumar S, Gonyo P, Rana U, Liu Z, Wang B, Duong WQ, Yang Z, Williams CL, Miao QR. The Nogo-B receptor promotes Ras plasma membrane localization and activation. Oncogene 2017; 36:3406-3416. [PMID: 28068323 PMCID: PMC5472485 DOI: 10.1038/onc.2016.484] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 11/08/2016] [Accepted: 11/15/2016] [Indexed: 12/11/2022]
Abstract
The localization of prenylated Ras at the plasma membrane promotes activation of Ras by receptor tyrosine kinases and stimulates oncogenic signaling by mutant Ras. The Nogo-B receptor (NgBR) is a transmembrane receptor that contains a conserved hydrophobic pocket. Here, we demonstrate that the NgBR promotes the membrane accumulation of Ras by directly binding prenylated Ras at the plasma membrane. We show that NgBR knockdown diminishes the membrane localization of Ras in multiple cell types. NgBR overexpression in NIH-3T3 fibroblasts increases membrane-associated Ras, induces the transformed phenotype in vitro, and promotes the formation of fibrosarcoma in nude mice. NgBR knockdown in human breast cancer cells reduces Ras membrane localization, inhibits EGF-stimulated Ras signaling, and diminishes tumorigenesis of xenografts in nude mice. Our data demonstrate that NgBR is a unique receptor that promotes accumulation of prenylated Ras at the plasma membrane and promotes EGF pathways.
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Affiliation(s)
- B Zhao
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Key Laboratory of Separation Science, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
| | - W Hu
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - S Kumar
- Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - P Gonyo
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - U Rana
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Z Liu
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - B Wang
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Pathology, China-Japan Friendship Hospital, Beijing, China
| | - W Q Duong
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Z Yang
- Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI, USA
| | - C L Williams
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Q R Miao
- Division of Pediatric Surgery, Department of Surgery, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Divisions of Pediatric Pathology, Department of Pathology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
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17
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Motta M, Chillemi G, Fodale V, Cecchetti S, Coppola S, Stipo S, Cordeddu V, Macioce P, Gelb BD, Tartaglia M. SHOC2 subcellular shuttling requires the KEKE motif-rich region and N-terminal leucine-rich repeat domain and impacts on ERK signalling. Hum Mol Genet 2016; 25:3824-3835. [PMID: 27466182 DOI: 10.1093/hmg/ddw229] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/04/2016] [Accepted: 07/08/2016] [Indexed: 11/15/2022] Open
Abstract
SHOC2 is a scaffold protein composed almost entirely by leucine-rich repeats (LRRs) and having an N-terminal region enriched in alternating lysine and glutamate/aspartate residues (KEKE motifs). SHOC2 acts as a positive modulator of the RAS-RAF-MEK-ERK signalling cascade by favouring stable RAF1 interaction with RAS. We previously reported that the p.Ser2Gly substitution in SHOC2 underlies Mazzanti syndrome, a RASopathy clinically overlapping Noonan syndrome, promoting N-myristoylation and constitutive targeting of the mutant to the plasma membrane. We also documented transient nuclear translocation of wild-type SHOC2 upon EGF stimulation, suggesting a more complex function in signal transduction.Here, we characterized the domains controlling SHOC2 shuttling between the nucleus and cytoplasm, and those contributing to SHOC2S2G mistargeting to the plasma membrane, analysed the structural organization of SHOC2's LRR motifs, and determined the impact of SHOC2 mislocalization on ERK signalling. We show that LRRs 1 to 13 constitute a structurally recognizable domain required for SHOC2 import into the nucleus and constitutive targeting of SHOC2S2G to the plasma membrane, while the KEKE motif-rich region is necessary to achieve efficient SHOC2 export from the nucleus. We also document that SHOC2S2G localizes both in raft and non-raft domains, and that it translocates to the non-raft domains following stimulation. Finally, we demonstrate that SHOC2 trapping at different subcellular sites has a diverse impact on ERK signalling strength and dynamics, suggesting a dual counteracting modulatory role of SHOC2 in the control of ERK signalling exerted at different intracellular compartments.
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Affiliation(s)
- Marialetizia Motta
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Giovanni Chillemi
- CINECA, SCAI-SuperComputing Applications and Innovation Department, Rome, Italy
| | | | | | - Simona Coppola
- Italian National Centre for Rare Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Silvia Stipo
- Department of Hematology, Oncology and Molecular Medicine
| | | | | | - Bruce D Gelb
- The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, Rome, Italy
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18
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Zhou B, Der CJ, Cox AD. The role of wild type RAS isoforms in cancer. Semin Cell Dev Biol 2016; 58:60-9. [PMID: 27422332 DOI: 10.1016/j.semcdb.2016.07.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 01/03/2023]
Abstract
Mutationally activated RAS proteins are critical oncogenic drivers in nearly 30% of all human cancers. As with mutant RAS, the role of wild type RAS proteins in oncogenesis, tumour maintenance and metastasis is context-dependent. Complexity is introduced by the existence of multiple RAS genes (HRAS, KRAS, NRAS) and protein "isoforms" (KRAS4A, KRAS4B), by the ever more complicated network of RAS signaling, and by the increasing identification of numerous genetic aberrations in cancers that do and do not harbour mutant RAS. Numerous mouse model carcinogenesis studies and examination of patient tumours reveal that, in RAS-mutant cancers, wild type RAS proteins are likely to serve as tumour suppressors when the mutant RAS is of the same isoform. This evidence is particularly robust in KRAS mutant cancers, which often display suppression or loss of wild type KRAS, but is not as strong for NRAS. In contrast, although not yet fully elucidated, the preponderance of evidence indicates that wild type RAS proteins play a tumour promoting role when the mutant RAS is of a different isoform. In non-RAS mutant cancers, wild type RAS is recognized as a mediator of oncogenic signaling due to chronic activation of upstream receptor tyrosine kinases that feed through RAS. Additionally, in the absence of mutant RAS, activation of wild type RAS may drive cancer upon the loss of negative RAS regulators such as NF1 GAP or SPRY proteins. Here we explore the current state of knowledge with respect to the roles of wild type RAS proteins in human cancers.
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Affiliation(s)
- Bingying Zhou
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA.
| | - Channing J Der
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA.
| | - Adrienne D Cox
- Department of Pharmacology, Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA.
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19
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Patra S, Erwin N, Winter R. Translational Dynamics of Lipidated Ras Proteins in the Presence of Crowding Agents and Compatible Osmolytes. Chemphyschem 2016; 17:2164-9. [PMID: 27028423 DOI: 10.1002/cphc.201600179] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Indexed: 11/07/2022]
Abstract
Ras proteins are small GTPases and are involved in transmitting signals that control cell growth, differentiation, and proliferation. Since the cell cytoplasm is crowded with different macromolecules, understanding the translational dynamics of Ras proteins in crowded environments is crucial to yielding deeper insight into their reactivity and function. Herein, the translational dynamics of lipidated N-Ras and K-Ras4B is studied in the bulk and in the presence of a macromolecular crowder (Ficoll) and the compatible osmolyte and microcrowder sucrose by fluorescence correlation spectroscopy. The results reveal that N-Ras forms dimers due to the presence of its lipid moiety in the hypervariable region, whereas K-Ras4B remains in its monomeric form in the bulk. Addition of a macromolecular crowding agent gradually favors clustering of the Ras proteins. In 20 wt % Ficoll N-Ras forms trimers and K-Ras4B dimers. Concentrations of sucrose up to 10 wt % foster formation of N-Ras trimers and K-Ras dimers as well. The results can be rationalized in terms of the excluded-volume effect, which enhances the association of the proteins, and, for the higher concentrations, by limited-hydration conditions. The results of this study shed new light on the association state of these proteins in a crowded environment. This is of particular interest for the Ras proteins, because their solution state-monomeric or clustered-influences their membrane-partitioning behavior and their interplay with cytosolic interaction partners.
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Affiliation(s)
- Satyajit Patra
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
| | - Nelli Erwin
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
| | - Roland Winter
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany.
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20
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Chung JK, Lee YK, Lam HYM, Groves JT. Covalent Ras Dimerization on Membrane Surfaces through Photosensitized Oxidation. J Am Chem Soc 2016; 138:1800-3. [PMID: 26812279 PMCID: PMC5515073 DOI: 10.1021/jacs.5b12648] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ras, a small GTPase found primarily on the inner leaflet of the plasma membrane, is an important signaling node and an attractive target for anticancer therapies. Lateral organization of Ras on cellular membranes has long been a subject of intense research; in particular, whether it forms dimers on membranes as part of its regulatory function has been a point of great interest. Here we report Ras dimer formation on membranes by Type II photosensitization reactions, in which molecular oxygen mediates the radicalization of proteins under typical fluorescence experimental conditions. The presence of Ras dimers on membranes was detected by diffusion-based fluorescence techniques including fluorescence correlation spectroscopy and single particle tracking, and molecular weights of the stable covalently coupled species were confirmed by gel electrophoresis. Fluorescence spectroscopy implicates interprotein dityrosine as one of the dimerization motifs. The specific surface tyrosine distribution on Ras renders the protein especially sensitive to this reaction, and point mutations affecting surface tyrosines are observed to alter dimerization potential. The photosensitization reactions are reflective of physiological oxidative stress induced by reactive oxygen species, suggesting such processes may occur naturally and influence signaling pathways in cells.
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Affiliation(s)
| | | | | | - Jay T. Groves
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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21
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Wehrens M, ten Wolde PR, Mugler A. Positive feedback can lead to dynamic nanometer-scale clustering on cell membranes. J Chem Phys 2015; 141:205102. [PMID: 25429963 DOI: 10.1063/1.4901888] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Clustering of molecules on biological membranes is a widely observed phenomenon. A key example is the clustering of the oncoprotein Ras, which is known to be important for signal transduction in mammalian cells. Yet, the mechanism by which Ras clusters form and are maintained remains unclear. Recently, it has been discovered that activated Ras promotes further Ras activation. Here we show using particle-based simulation that this positive feedback is sufficient to produce persistent clusters of active Ras molecules at the nanometer scale via a dynamic nucleation mechanism. Furthermore, we find that our cluster statistics are consistent with experimental observations of the Ras system. Interestingly, we show that our model does not support a Turing regime of macroscopic reaction-diffusion patterning, and therefore that the clustering we observe is a purely stochastic effect, arising from the coupling of positive feedback with the discrete nature of individual molecules. These results underscore the importance of stochastic and dynamic properties of reaction diffusion systems for biological behavior.
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Affiliation(s)
- Martijn Wehrens
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | | | - Andrew Mugler
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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22
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Prakash P, Sayyed-Ahmad A, Gorfe AA. pMD-Membrane: A Method for Ligand Binding Site Identification in Membrane-Bound Proteins. PLoS Comput Biol 2015; 11:e1004469. [PMID: 26506102 PMCID: PMC4623977 DOI: 10.1371/journal.pcbi.1004469] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/27/2015] [Indexed: 12/22/2022] Open
Abstract
Probe-based or mixed solvent molecular dynamics simulation is a useful approach for the identification and characterization of druggable sites in drug targets. However, thus far the method has been applied only to soluble proteins. A major reason for this is the potential effect of the probe molecules on membrane structure. We have developed a technique to overcome this limitation that entails modification of force field parameters to reduce a few pairwise non-bonded interactions between selected atoms of the probe molecules and bilayer lipids. We used the resulting technique, termed pMD-membrane, to identify allosteric ligand binding sites on the G12D and G13D oncogenic mutants of the K-Ras protein bound to a negatively charged lipid bilayer. In addition, we show that differences in probe occupancy can be used to quantify changes in the accessibility of druggable sites due to conformational changes induced by membrane binding or mutation.
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Affiliation(s)
- Priyanka Prakash
- University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, Houston, Texas, United States of America
| | - Abdallah Sayyed-Ahmad
- University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, Houston, Texas, United States of America
| | - Alemayehu A. Gorfe
- University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, Houston, Texas, United States of America
- * E-mail:
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23
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Nussinov R, Jang H, Tsai CJ. Oligomerization and nanocluster organization render specificity. Biol Rev Camb Philos Soc 2015; 90:587-98. [PMID: 24917483 PMCID: PMC4263682 DOI: 10.1111/brv.12124] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 04/30/2014] [Accepted: 05/14/2014] [Indexed: 12/11/2022]
Abstract
Nanoclusters are anchored to membranes, either within them or in the cytoplasm latched onto the cytoskeleton, whose reorganization can regulate their activity. Nanoclusters have been viewed in terms of cooperativity and activation; here we perceive nanocluster organization from a conformational standpoint. This leads us to suggest that while single molecules encode activity, nanoclusters induce specificity, and that this is their main evolutionary aim. Distinct, isoform-specific nanocluster organization can drive the preferred effector (and ligand) interactions and thereby designate signalling pathways. The absence of detailed structural information across the nanocluster, due to size and dynamics, hinders an in-depth grasp of its mechanistic features; however, available data already capture some of the principles and their functional 'raison d'être'. Collectively, clustering lends stability and reduces the likelihood of proteolytic cleavage; it also increases the effective local concentration and enables efficient cooperative activation. However, clustering does not determine the ability of the single molecule to function. Drugs targeting nanoclusters can attenuate activity by hampering cooperativity; however, this may not perturb activation and signalling, which originate from the molecules themselves, and as such, are likely to endure. What then is the major role of nanoclustering? Assuming that single molecules evolved first, with a subsequent increase in cellular complexity and emergence of highly similar isoform variants, evolution faced the threat of signalling promiscuity. We reason that this potential risk was thwarted by oligomerization and clustering; clustering confers higher specificity, and a concomitant extra layer of cellular control. In our Ras example, signalling will be more accurate as a dimer than as a monomer, where its isomer specificity could be compromised.
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Affiliation(s)
- Ruth Nussinov
- Cancer and Inflammation Program, National Cancer Institute, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702, USA
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Hyunbum Jang
- Cancer and Inflammation Program, National Cancer Institute, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702, USA
| | - Chung-Jung Tsai
- Cancer and Inflammation Program, National Cancer Institute, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702, USA
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24
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Burd CE, Liu W, Huynh MV, Waqas MA, Gillahan JE, Clark KS, Fu K, Martin BL, Jeck WR, Souroullas GP, Darr DB, Zedek DC, Miley MJ, Baguley BC, Campbell SL, Sharpless NE. Mutation-specific RAS oncogenicity explains NRAS codon 61 selection in melanoma. Cancer Discov 2014; 4:1418-29. [PMID: 25252692 PMCID: PMC4258185 DOI: 10.1158/2159-8290.cd-14-0729] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
UNLABELLED NRAS mutation at codons 12, 13, or 61 is associated with transformation; yet, in melanoma, such alterations are nearly exclusive to codon 61. Here, we compared the melanoma susceptibility of an NrasQ61R knock-in allele to similarly designed KrasG12D and NrasG12D alleles. With concomitant p16INK4a inactivation, KrasG12D or NrasQ61R expression efficiently promoted melanoma in vivo, whereas NrasG12D did not. In addition, NrasQ61R mutation potently cooperated with Lkb1/Stk11 loss to induce highly metastatic disease. Functional comparisons of NrasQ61R and NrasG12D revealed little difference in the ability of these proteins to engage PI3K or RAF. Instead, NrasQ61R showed enhanced nucleotide binding, decreased intrinsic GTPase activity, and increased stability when compared with NrasG12D. This work identifies a faithful model of human NRAS-mutant melanoma, and suggests that the increased melanomagenecity of NrasQ61R over NrasG12D is due to heightened abundance of the active, GTP-bound form rather than differences in the engagement of downstream effector pathways. SIGNIFICANCE This work explains the curious predominance in human melanoma of mutations of codon 61 of NRAS over other oncogenic NRAS mutations. Using conditional "knock-in" mouse models, we show that physiologic expression of NRASQ61R, but not NRASG12D, drives melanoma formation.
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Affiliation(s)
- Christin E Burd
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio. Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio
| | - Wenjin Liu
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Minh V Huynh
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Meriam A Waqas
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio
| | - James E Gillahan
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio. Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio
| | - Kelly S Clark
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Kailing Fu
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Brit L Martin
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio
| | - William R Jeck
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - George P Souroullas
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - David B Darr
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Daniel C Zedek
- Department of Dermatology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Michael J Miley
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Bruce C Baguley
- Auckland Cancer Society Research Centre, University of Auckland, Auckland, New Zealand
| | - Sharon L Campbell
- The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina. Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Norman E Sharpless
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina. The Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
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25
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Clancy T, Hovig E. From proteomes to complexomes in the era of systems biology. Proteomics 2014; 14:24-41. [PMID: 24243660 DOI: 10.1002/pmic.201300230] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 10/22/2013] [Accepted: 11/06/2013] [Indexed: 01/16/2023]
Abstract
Protein complexes carry out almost the entire signaling and functional processes in the cell. The protein complex complement of a cell, and its network of complex-complex interactions, is referred to here as the complexome. Computational methods to predict protein complexes from proteomics data, resulting in network representations of complexomes, have recently being developed. In addition, key advances have been made toward understanding the network and structural organization of complexomes. We review these bioinformatics advances, and their discovery-potential, as well as the merits of integrating proteomics data with emerging methods in systems biology to study protein complex signaling. It is envisioned that improved integration of proteomics and systems biology, incorporating the dynamics of protein complexes in space and time, may lead to more predictive models of cell signaling networks for effective modulation.
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Affiliation(s)
- Trevor Clancy
- Department of Tumor Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
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Abstract
For centuries yeast species have been popular hosts for classical biotechnology processes, such as baking, brewing, and wine making, and more recently for recombinant proteins production, thanks to the advantages of unicellular organisms (i.e., ease of genetic manipulation and rapid growth) together with the ability to perform eukaryotic posttranslational modifications. Moreover, yeast cells have been used for few decades as a tool for identifying the genes and pathways involved in basic cellular processes such as the cell cycle, aging, and stress response. In the budding yeast S. cerevisiae the Ras/cAMP/PKA pathway is directly involved in the regulation of metabolism, cell growth, stress resistance, and proliferation in response to the availability of nutrients and in the adaptation to glucose, controlling cytosolic cAMP levels and consequently the cAMP-dependent protein kinase (PKA) activity. Moreover, Ras signalling has been identified in several pathogenic yeasts as a key controller for virulence, due to its involvement in yeast morphogenesis. Nowadays, yeasts are still useful for Ras-like proteins investigation, both as model organisms and as a test tube to study variants of heterologous Ras-like proteins.
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Affiliation(s)
- Renata Tisi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
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27
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Baker R, Wilkerson EM, Sumita K, Isom DG, Sasaki AT, Dohlman HG, Campbell SL. Differences in the regulation of K-Ras and H-Ras isoforms by monoubiquitination. J Biol Chem 2013; 288:36856-62. [PMID: 24247240 DOI: 10.1074/jbc.c113.525691] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Ras GTPases are signaling switches that control critical cellular processes including gene expression, differentiation, and apoptosis. The major Ras isoforms (K, H, and N) contain a conserved core GTPase domain, but have distinct biological functions. Among the three Ras isoforms there are clear differences in post-translational regulation, which contribute to differences in localization and signaling output. Modification by ubiquitination was recently reported to activate Ras signaling in cells, but the mechanisms of activation are not well understood. Here, we show that H-Ras is activated by monoubiquitination and that ubiquitination at Lys-117 accelerates intrinsic nucleotide exchange, thereby promoting GTP loading. This mechanism of Ras activation is distinct from K-Ras monoubiquitination at Lys-147, which leads to impaired regulator-mediated GTP hydrolysis. These findings reveal that different Ras isoforms are monoubiquitinated at distinct sites, with distinct mechanisms of action, but with a common ability to chronically activate the protein in the absence of a receptor signal or oncogenic mutation.
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Affiliation(s)
- Rachael Baker
- From the Departments of Biochemistry and Biophysics and
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Prakash P, Gorfe AA. Lessons from computer simulations of Ras proteins in solution and in membrane. Biochim Biophys Acta Gen Subj 2013; 1830:5211-8. [PMID: 23906604 DOI: 10.1016/j.bbagen.2013.07.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND A great deal has been learned over the last several decades about the function of Ras proteins in solution and membrane environments. While much of this knowledge has been derived from a plethora of experimental techniques, computer simulations have also played a substantial role. SCOPE OF REVIEW Our goal here is to summarize the contribution of molecular simulations to our current understanding of normal and aberrant Ras function. We focus on lessons from molecular dynamics simulations in aqueous and membrane environments. MAJOR CONCLUSIONS The central message is that a close interaction between theory and simulation on the one hand and cell-biological, spectroscopic and other experimental approaches on the other has played, and will likely continue to play, a vital role in Ras research. GENERAL SIGNIFICANCE Atomistic insights emerging from detailed simulations of Ras in solution and in bilayers may be the key to unlock the secret that to date prevented development of selective anti-Ras inhibitors for cancer therapy.
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Affiliation(s)
- Priyanka Prakash
- University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, 6431 Fannin St., Houston, TX 77030, USA
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29
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Harmon RM, Simpson CL, Johnson JL, Koetsier JL, Dubash AD, Najor NA, Sarig O, Sprecher E, Green KJ. Desmoglein-1/Erbin interaction suppresses ERK activation to support epidermal differentiation. J Clin Invest 2013; 123:1556-70. [PMID: 23524970 DOI: 10.1172/jci65220] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 01/17/2013] [Indexed: 01/27/2023] Open
Abstract
Genetic disorders of the Ras/MAPK pathway, termed RASopathies, produce numerous abnormalities, including cutaneous keratodermas. The desmosomal cadherin, desmoglein-1 (DSG1), promotes keratinocyte differentiation by attenuating MAPK/ERK signaling and is linked to striate palmoplantar keratoderma (SPPK). This raises the possibility that cutaneous defects associated with SPPK and RASopathies share certain molecular faults. To identify intermediates responsible for executing the inhibition of ERK by DSG1, we conducted a yeast 2-hybrid screen. The screen revealed that Erbin (also known as ERBB2IP), a known ERK regulator, binds DSG1. Erbin silencing disrupted keratinocyte differentiation in culture, mimicking aspects of DSG1 deficiency. Furthermore, ERK inhibition and the induction of differentiation markers by DSG1 required both Erbin and DSG1 domains that participate in binding Erbin. Erbin blocks ERK signaling by interacting with and disrupting Ras-Raf scaffolds mediated by SHOC2, a protein genetically linked to the RASopathy, Noonan-like syndrome with loose anagen hair (NS/LAH). DSG1 overexpression enhanced this inhibitory function, increasing Erbin-SHOC2 interactions and decreasing Ras-SHOC2 interactions. Conversely, analysis of epidermis from DSG1-deficient patients with SPPK demonstrated increased Ras-SHOC2 colocalization and decreased Erbin-SHOC2 colocalization, offering a possible explanation for the observed epidermal defects. These findings suggest a mechanism by which DSG1 and Erbin cooperate to repress MAPK signaling and promote keratinocyte differentiation.
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Affiliation(s)
- Robert M Harmon
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
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30
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Bellavia M, Gioviale MC, Damiano G, Palumbo VD, Spinelli G, Buscemi G, Lo Monte AI. Dissecting the different biological effects of oncogenic Ras isoforms in cancer cell lines: could stimulation of oxidative stress be the one more weapon of H-Ras? Regulation of oxidative stress and Ras biological effects. Med Hypotheses 2012; 79:731-4. [PMID: 22981836 DOI: 10.1016/j.mehy.2012.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 08/06/2012] [Accepted: 08/15/2012] [Indexed: 11/25/2022]
Abstract
Ras proteins are small GTPase functioning as molecular switches that, in response to particular extracellular signalling, as growth factors, activate a diverse array of intracellular effector cascades regulating cell proliferation, differentiation and apoptosis. Human tumours frequently express Ras proteins (Ha-, Ki-, N-Ras) activated by point mutations which contribute to malignant phenotype, including invasiveness and angiogenesis. Despite the common signalling pathways leading to similar cellular responses, studies clearly demonstrate unique roles of the Ras family members in normal and pathological conditions and the lack of functional redundancy seems to be explainable, at least in part, by the ability of Ras isoforms to localize in different microdomains to plasma membrane and intracellular organelles. This different intracellular compartmentalization could help Ras isoforms to contact different downstream effectors finally leading to different biological outcomes. Interestingly, it has also been shown that Ha- and Ki-Ras exert an opposite role in regulating intracellular redox status. In this regard we suggest that H-Ras specific induction of ROS (reactive oxygen species) production could be one of the main determinants of the invasive phenotype which characterize cancer cells harbouring H-Ras mutations. In our hypothesis then, while K-Ras (not able to promote oxidative stress) could mainly contribute to cancer progression and invasiveness through activation of MAPK and PI3K, H-Ras-mediated oxidative stress could play a unique role in modulation of intercellular contacts leading to a loss of cell adhesion and eventually also to a metastatic spread.
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Affiliation(s)
- Maurizio Bellavia
- Department of Surgical and Oncological Disciplines, University of Palermo, Palermo, Italy.
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31
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Ras and Rap1 govern spatiotemporal dynamic of activated ERK in pituitary living cells. Cell Signal 2012; 24:2237-48. [PMID: 22940095 DOI: 10.1016/j.cellsig.2012.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 08/02/2012] [Accepted: 08/14/2012] [Indexed: 11/22/2022]
Abstract
The Ras/Raf/MEK/ERK is a conserved signalling pathway involved in the control of fundamental cellular processes. Despite extensive research, how this pathway can process a myriad of diverse extracellular inputs into substrate specificity to determine biological outcomes is not fully understood. It has been established that the ERK1/2 pathway is an integrative point in the control of the pituitary function exerted by various extracellular signals. In addition we previously established that the GTPases Ras and Rap1 play a key role in the regulation of ERK1/2-dependent prolactin transcription by EGF or the cAMP-dependent neuropeptide VIP. In this report, using the FRET-based biosensor of ERK activity (EKAR) in the pituitary GH4C1 cell line, we show that both EGF and VIP tightly control the spatiotemporal dynamic of activated ERK with different magnitude and duration. Importantly, we provide the first evidence of a differential control of cytoplasmic and nuclear pools of activated ERK by the GTPases Ras and Rap1. Ras is required for nuclear magnitude and duration of EGF-dependent ERK activation, whereas it is required for both VIP-activated cytoplasmic and nuclear ERK pools. Rap1 is exclusively involved in VIP-activated ERK nuclear pool. Moreover, consistent with the control of the nuclear pool of activated ERK by the GTPases, we observe the same differential role of Ras and Rap1 on ERK nuclear translocation triggered by EGF or VIP. Together these findings identify Ras and Rap1 as determinant partners in shaping nuclear and cytoplasmic ERK kinetics in response to EGF and VIP, which in turn should control pituitary secretion.
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32
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Wurtzel JGT, Kumar P, Goldfinger LE. Palmitoylation regulates vesicular trafficking of R-Ras to membrane ruffles and effects on ruffling and cell spreading. Small GTPases 2012; 3:139-53. [PMID: 22751447 PMCID: PMC3442799 DOI: 10.4161/sgtp.21084] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
In this study we investigated the dynamics of R-Ras intracellular trafficking and its contributions to the unique roles of R-Ras in membrane ruffling and cell spreading. Wild type and constitutively active R-Ras localized to membranes of both Rab11- and transferrin-positive and -negative vesicles, which trafficked anterograde to the leading edge in migrating cells. H-Ras also co-localized with R-Ras in many of these vesicles in the vicinity of the Golgi, but R-Ras and H-Ras vesicles segregated proximal to the leading edge, in a manner dictated by the C-terminal membrane-targeting sequences. These segregated vesicle trafficking patterns corresponded to distinct modes of targeting to membrane ruffles at the leading edge. Geranylgeranylation was required for membrane anchorage of R-Ras, whereas palmitoylation was required for exit from the Golgi in post-Golgi vesicle membranes and trafficking to the plasma membrane. R-Ras vesicle membranes did not contain phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3), whereas R-Ras co-localized with PtdIns(3,4,5)P3 in membrane ruffles. Finally, palmitoylation-deficient R-Ras blocked membrane ruffling, R-Ras/PI3-kinase interaction, enrichment of PtdIns(3,4,5)P3 at the plasma membrane, and R-Ras-dependent cell spreading. Thus, lipid modification of R-Ras dictates its vesicle trafficking, targeting to membrane ruffles, and its unique roles in localizing PtdIns(3,4,5)P3 to ruffles and promoting cell spreading.
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Affiliation(s)
- Jeremy G T Wurtzel
- Department of Anatomy & Cell Biology, The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA
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33
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Triffo SB, Huang HH, Smith AW, Chou ET, Groves JT. Monitoring lipid anchor organization in cell membranes by PIE-FCCS. J Am Chem Soc 2012; 134:10833-42. [PMID: 22631607 PMCID: PMC3626236 DOI: 10.1021/ja300374c] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study examines the dynamic co-localization of lipid-anchored fluorescent proteins in living cells using pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS) and fluorescence lifetime analysis. Specifically, we look at the pairwise co-localization of anchors from lymphocyte cell kinase (LCK: myristoyl, palmitoyl, palmitoyl), RhoA (geranylgeranyl), and K-Ras (farnesyl) proteins in different cell types. In Jurkat cells, a density-dependent increase in cross-correlation among RhoA anchors is observed, while LCK anchors exhibit a more moderate increase and broader distribution. No correlation was detected among K-Ras anchors or between any of the different anchor types studied. Fluorescence lifetime data reveal no significant Förster resonance energy transfer in any of the data. In COS 7 cells, minimal correlation was detected among LCK or RhoA anchors. Taken together, these observations suggest that some lipid anchors take part in anchor-specific co-clustering with other existing clusters of native proteins and lipids in the membrane. Importantly, these observations do not support a simple interpretation of lipid anchor-mediated organization driven by partitioning based on binary lipid phase separation.
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Affiliation(s)
- Sara B Triffo
- Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, California 94720, USA
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34
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Mohammad G, Kowluru RA. Diabetic retinopathy and signaling mechanism for activation of matrix metalloproteinase-9. J Cell Physiol 2012; 227:1052-61. [PMID: 21567393 DOI: 10.1002/jcp.22822] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In the pathogenesis of diabetic retinopathy, H-Ras (a small molecular weight G-protein) and matrix metalloproteinase-9 (MMP9) act as pro-apoptotic, accelerating the apoptosis of retinal capillary cells, a phenomenon that predicts its development and the activation of MMP9 is under the control of H-Ras. The goal of this study is to elucidate the cellular mechanism by which H-Ras activates MMP9 culminating in the development of diabetic retinopathy. Using isolated retinal endothelial cells, the effect of regulation of H-Ras downstream signaling cascade, Raf-1, MEK, and ERK, was investigated on glucose-induced activation of MMP9. In vitro results were confirmed in the retina obtained from diabetic mice manipulated for MMP9 gene, and also in the retinal microvasculature obtained from human donors with diabetic retinopathy. Regulation of Raf-1/MEK/ERK by their specific siRNAs and pharmacologic inhibitors prevented glucose-induced activation of MMP9 in retinal endothelial cells. In MMP9-KO mice, diabetes had no effect on retinal MMP9 activation, and H-Ras/Raf-1/MEK signaling cascade remained normal. Similarly, donors with diabetic retinopathy had increased MMP9 activity in their retinal microvessels, the site of histopathology associated with diabetic retinopathy, and this was accompanied by activated H-Ras signaling pathway (Raf-1/ERK). Collectively, these results suggest that Ras/Raf-1/MEK/ERK cascade has an important role in the activation of retinal MMP9 resulting in the apoptosis of its capillary cells. Understanding the upstream mechanism responsible for the activation of MMP9 should help identify novel molecular targets for future pharmacological interventions to inhibit the development/progression of diabetic retinopathy.
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Affiliation(s)
- Ghulam Mohammad
- Kresge Eye Institute, Wayne State University, Detroit, Michigan 48201, USA
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35
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Pietilä R, Nätynki M, Tammela T, Kangas J, Pulkki KH, Limaye N, Vikkula M, Koh GY, Saharinen P, Alitalo K, Eklund L. Ligand oligomerization state controls Tie2 receptor trafficking and angiopoietin-2-specific responses. J Cell Sci 2012; 125:2212-23. [PMID: 22357955 DOI: 10.1242/jcs.098020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Angiopoietin 1 (Ang1) is an activating ligand for the endothelial receptor tyrosine kinase Tie2, whereas Ang2 acts as a context-dependent agonist or antagonist that has a destabilizing effect on the vasculature. The molecular mechanisms responsible for the versatile functions of Ang2 are poorly understood. We show here that Ang2, but not Ang1, induces Tie2 translocation to the specific cell-matrix contact sites located at the distal end of focal adhesions. The Ang2-specific Tie2 translocation was associated with distinct Tie2 activation and downstream signals which differed from those of Ang1, and led to impaired cell motility and weak cell-matrix adhesion. We demonstrate that the different oligomeric or multimeric forms of the angiopoietins induce distinct patterns of Tie2 trafficking; the lower oligomerization state of native Ang2 was crucial for the Ang2-specific Tie2 redistribution, whereas multimeric structures of Ang1 and Ang2 induced similar responses. The Ang2-specific Tie2 trafficking to cell-matrix contacts was also dependent on the cell substratum, α2β1-integrin-containing cell-matrix adhesion sites and intact microtubules. Our data indicate that the different subcellular trafficking of Tie2-Ang2 and Tie2-Ang1 complexes generates ligand-specific responses in the angiopoietin-Tie signaling pathway, including modulation of cell-matrix interactions.
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Affiliation(s)
- Riikka Pietilä
- Oulu Center for Cell-Matrix Research, Biocenter Oulu and Department of Medical Biochemistry and Molecular Biology, University of Oulu, Oulu, Finland
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36
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Fillatre J, Delacour D, Van Hove L, Bagarre T, Houssin N, Soulika M, Veitia RA, Moreau J. Dynamics of the subcellular localization of RalBP1/RLIP through the cell cycle: the role of targeting signals and of protein-protein interactions. FASEB J 2012; 26:2164-74. [PMID: 22319010 DOI: 10.1096/fj.11-196451] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The small G protein Ras regulates many cell processes, such as gene expression, proliferation, apoptosis, and cell differentiation. Its mutations are associated with one-third of all cancers. Ras functions are mediated, at least in part, by Ral proteins and their downstream effector the Ral-binding protein 1 (RalBP1). RalBP1 is involved in endocytosis and in regulating the dynamics of the actin cytoskeleton. It also regulates early development since it is required for the completion of gastrulation in Xenopus laevis. RalBP1 has also been reported to be the main transporter of glutathione electrophiles, and it is involved in multidrug resistance. Such a variety of functions could be explained by a differential regulation of RalBP1 localization. In this study, we have detected endogenous RalBP1 in the nucleus of interphasic cells. This nuclear targeting is mediated by nuclear localization sequences that map to the N-terminal third of the protein. Moreover, in X. laevis embryos, a C-terminal coiled-coil sequence mediates RalBP1 retention in the nucleus. We have also observed RalBP1 at the level of the actin cytoskeleton, a localization that depends on interaction of the protein with active Ral. During mitosis RalBP1 also associates with the mitotic spindle and the centrosome, a localization that could be negatively regulated by active Ral. Finally, we demonstrate the presence of post-transcriptional and post-translational isoforms of RalBP1 lacking the Ral-binding domain, which opens new possibilities for the existence of Ral-independent functions.
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Affiliation(s)
- Jonathan Fillatre
- Mécanismes Moléculaires du Développement, Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité. 15, rue Hélène Brion. 75205 Paris, France
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A palmitoylation switch mechanism regulates Rac1 function and membrane organization. EMBO J 2011; 31:534-51. [PMID: 22157745 DOI: 10.1038/emboj.2011.446] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 11/16/2011] [Indexed: 01/02/2023] Open
Abstract
The small GTPase Rac1 plays important roles in many processes, including cytoskeletal reorganization, cell migration, cell-cycle progression and gene expression. The initiation of Rac1 signalling requires at least two mechanisms: GTP loading via the guanosine triphosphate (GTP)/guanosine diphosphate (GDP) cycle, and targeting to cholesterol-rich liquid-ordered plasma membrane microdomains. Little is known about the molecular mechanisms governing this specific compartmentalization. We show that Rac1 can incorporate palmitate at cysteine 178 and that this post-translational modification targets Rac1 for stabilization at actin cytoskeleton-linked ordered membrane regions. Palmitoylation of Rac1 requires its prior prenylation and the intact C-terminal polybasic region and is regulated by the triproline-rich motif. Non-palmitoylated Rac1 shows decreased GTP loading and lower association with detergent-resistant (liquid-ordered) membranes (DRMs). Cells expressing no Rac1 or a palmitoylation-deficient mutant have an increased content of disordered membrane domains, and markers of ordered membranes isolated from Rac1-deficient cells do not correctly partition in DRMs. Importantly, cells lacking Rac1 palmitoylation show spreading and migration defects. These data identify palmitoylation as a mechanism for Rac1 function in actin cytoskeleton remodelling by controlling its membrane partitioning, which in turn regulates membrane organization.
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38
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Castellano E, Santos E. Functional specificity of ras isoforms: so similar but so different. Genes Cancer 2011; 2:216-31. [PMID: 21779495 DOI: 10.1177/1947601911408081] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
H-ras, N-ras, and K-ras are canonical ras gene family members frequently activated by point mutation in human cancers and coding for 4 different, highly related protein isoforms (H-Ras, N-Ras, K-Ras4A, and K-Ras4B). Their expression is nearly ubiquitous and broadly conserved across eukaryotic species, although there are quantitative and qualitative differences of expression depending on the tissue and/or developmental stage under consideration. Extensive functional studies have determined during the last quarter century that these Ras gene products are critical components of signaling pathways that control eukaryotic cell proliferation, survival, and differentiation. However, because of their homology and frequent coexpression in various cellular contexts, it remained unclear whether the different Ras proteins play specific or overlapping functional roles in physiological and pathological processes. Initially, their high degree of sequence homology and the observation that all Ras isoforms share common sets of downstream effectors and upstream activators suggested that they were mostly redundant functionally. In contrast, the notion of functional specificity for each of the different Ras isoforms is supported at present by an increasing body of experimental observations, including 1) the fact that different ras isoforms are preferentially mutated in specific types of tumors or developmental disorders; 2) the different transforming potential of transfected ras genes in different cell contexts; 3) the distinct sensitivities exhibited by the various Ras family members for modulation by different GAPs or GEFs; 4) the demonstration that different Ras isoforms follow distinct intracellular processing pathways and localize to different membrane microdomains or subcellular compartments; 5) the different phenotypes displayed by genetically modified animal strains for each of the 3 ras loci; and 6) the specific transcriptional networks controlled by each isoform in different cellular settings.
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Affiliation(s)
- Esther Castellano
- Signal Transduction Laboratory, Cancer Research UK London Research Institute, London, UK
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39
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Chaturvedi A, Martz R, Dorward D, Waisberg M, Pierce SK. Endocytosed BCRs sequentially regulate MAPK and Akt signaling pathways from intracellular compartments. Nat Immunol 2011; 12:1119-26. [PMID: 21964606 DOI: 10.1038/ni.2116] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 08/23/2011] [Indexed: 01/15/2023]
Abstract
Binding of antigen to the B cell antigen receptor (BCR) triggers both BCR signaling and endocytosis. How endocytosis regulates BCR signaling remains unknown. Here we report that BCR signaling was not extinguished by endocytosis of BCRs; instead, BCR signaling initiated at the plasma membrane continued as the BCR trafficked intracellularly with the sequential phosphorylation of kinases. Blocking the endocytosis of BCRs resulted in the recruitment of both proximal and downstream kinases to the plasma membrane, where mitogen-activated protein kinases (MAPKs) were hyperphosphorylated and the kinase Akt and its downstream target Foxo were hypophosphorylated, which led to the dysregulation of gene transcription controlled by these pathways. Thus, the cellular location of the BCR serves to compartmentalize kinase activation to regulate the outcome of signaling.
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Affiliation(s)
- Akanksha Chaturvedi
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA.
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40
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Ghai R, Collins BM. PX-FERM proteins: A link between endosomal trafficking and signaling? Small GTPases 2011; 2:259-263. [PMID: 22292128 DOI: 10.4161/sgtp.2.5.17276] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 07/13/2011] [Accepted: 07/15/2011] [Indexed: 01/08/2023] Open
Abstract
Endosomes are the primary organelle where decisions are made as to whether endocytosed proteins will be sorted into degradative trafficking pathways or recycled back to the plasma membrane. This balance between cellular uptake and recycling regulates the plasma membrane composition and is therefore critical for many cellular processes such as nutrient uptake, neuronal transmission and cell migration.1 In addition to its well-known role in membrane trafficking, the endosome is increasingly being recognized as a critical cellular domain for regulated cell signaling. We recently showed that several proteins that regulate endosomal recycling, SNX17, SNX27 and SNX31 are structurally and functionally related.2 These proteins use an unusual FERM domain to bind specific endosomal cargo molecules, and most interestingly, we also found that these proteins use the same FERM domain to associate with the activated Ras small GTPase. Here we speculate on the potential dual role of the PX-FERM proteins in endosomal transport and as scaffolds that may be involved in endosomal Ras signaling processes.
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Affiliation(s)
- Rajesh Ghai
- Institute for Molecular Bioscience; University of Queensland; St. Lucia, Queensland Australia
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Zacharogianni M, Kondylis V, Tang Y, Farhan H, Xanthakis D, Fuchs F, Boutros M, Rabouille C. ERK7 is a negative regulator of protein secretion in response to amino-acid starvation by modulating Sec16 membrane association. EMBO J 2011; 30:3684-700. [PMID: 21847093 DOI: 10.1038/emboj.2011.253] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 07/07/2011] [Indexed: 01/08/2023] Open
Abstract
RNAi screening for kinases regulating the functional organization of the early secretory pathway in Drosophila S2 cells has identified the atypical Mitotic-Associated Protein Kinase (MAPK) Extracellularly regulated kinase 7 (ERK7) as a new modulator. We found that ERK7 negatively regulates secretion in response to serum and amino-acid starvation, in both Drosophila and human cells. Under these conditions, ERK7 turnover through the proteasome is inhibited, and the resulting higher levels of this kinase lead to a modification in a site within the C-terminus of Sec16, a key ER exit site component. This post-translational modification elicits the cytoplasmic dispersion of Sec16 and the consequent disassembly of the ER exit sites, which in turn results in protein secretion inhibition. We found that ER exit site disassembly upon starvation is TOR complex 1 (TORC1) independent, showing that under nutrient stress conditions, cell growth is not only inhibited at the transcriptional and translational levels, but also independently at the level of secretion by inhibiting the membrane flow through the early secretory pathway. These results reveal the existence of new signalling circuits participating in the complex regulation of cell growth.
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Affiliation(s)
- Margarita Zacharogianni
- Department of Cell Biology, Cell microscopy Centre, UMC Utrecht, Heidelberglaan, The Netherlands
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de la Vega M, Burrows JF, Johnston JA. Ubiquitination: Added complexity in Ras and Rho family GTPase function. Small GTPases 2011; 2:192-201. [PMID: 22145091 DOI: 10.4161/sgtp.2.4.16707] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 12/17/2022] Open
Abstract
The regulation of the small GTPases leading to their membrane localization has long been attributed to processing of their C-terminal CAAX box. As deregulation of many of these GTPases have been implicated in cancer and other disorders, prenylation and methylation of this CAAX box has been studied in depth as a possibility for drug targeting, but unfortunately, to date no drug has proved clinically beneficial. However, these GTPases also undergo other modifications that may be important for their regulation. Ubiquitination has long been demonstrated to regulate the fate of numerous cellular proteins and recently it has become apparent that many GTPases, along with their GAPs, GeFs and GDis, undergo ubiquitination leading to a variety of fates such as re-localization or degradation. in this review we focus on the recent literature demonstrating that the regulation of small GTPases by ubiquitination, either directly or indirectly, plays a considerable role in controlling their function and that targeting these modifications could be important for disease treatment.
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Affiliation(s)
- Michelle de la Vega
- Centre for Infection and Immunity; School of Medicine, Dentistry and Biomedical Sciences; Queen's University; Belfast, UK
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Liu AM, Lo RK, Guo EX, Ho MK, Ye RD, Wong YH. Gα16 interacts with tetratricopeptide repeat 1 (TPR1) through its β3 region to activate Ras independently of phospholipase Cβ signaling. BMC STRUCTURAL BIOLOGY 2011; 11:17. [PMID: 21486497 PMCID: PMC3098143 DOI: 10.1186/1472-6807-11-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 04/13/2011] [Indexed: 12/02/2022]
Abstract
Background G protein-coupled receptors constitute the largest family of cell surface receptors in the mammalian genome. As the core of the G protein signal transduction machinery, the Gα subunits are required to interact with multiple partners. The GTP-bound active state of many Gα subunits can bind a multitude of effectors and regulatory proteins. Yet it remains unclear if the different proteins utilize distinct or common structural motifs on the Gα subunit for binding. Using Gα16 as a model, we asked if its recently discovered adaptor protein tetratricopeptide repeat 1 (TPR1) binds to the same region as its canonical effector, phospholipase Cβ (PLCβ). Results We have examined the specificity of Gα16/TPR1 association by testing a series of chimeras between Gα16 and Gαz. TPR1 co-immunoprecipitated with Gα16 and more tightly with its constitutively active Gα16QL, but not Gαz. Progressive replacement of Gα16 sequence with the corresponding residues of Gαz eventually identified a stretch of six amino acids in the β3 region of Gα16 which are responsible for TPR1 interaction and the subsequent Ras activation. Insertion of these six residues into Gαz allowed productive TPR1-interaction. Since the β3 region only minimally contributes to interact with PLCβ, several chimeras exhibited differential abilities to stimulate PLCβ and Ras. The ability of the chimeras to activate downstream transcription factors such as signal transducer and activator of transcription 3 and nuclear factor κB appeared to be associated with PLCβ signaling. Conclusions Our results suggest that Gα16 can signal through TPR1/Ras and PLCβ simultaneously and independently. The β3 region of Gα16 is essential for interaction with TPR1 and the subsequent activation of Ras, but has relatively minor influence on the PLCβ interaction. Gα16 may utilize different structural domains to bind TPR1 and PLCβ.
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Affiliation(s)
- Andrew Mf Liu
- Division of Life Science and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Abstract
Signal transduction through Ras translates extracellular signals into biological responses, including cell proliferation, cell survival, growth, and differentiation. For these reasons, dysregulating Ras can have dramatic effects at the cellular and organismal levels. Germline mutations that increase Ras signaling disrupt development, whereas mutational activation of Ras in somatic cells can cause cancer. Thus, identifying additional mechanisms that positively or negatively regulate Ras could have profound implications for treating human diseases. New evidence identifies K-Ras monoubiquitination as a previously unknown means to potentiate Ras signaling.
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Affiliation(s)
- Cathie M Pfleger
- Department of Oncological Sciences, The Mount Sinai School of Medicine, New York, NY 10029, USA.
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45
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Abstract
The Ras family GTPases (Ras, Rap1, and Rap2) and their downstream mitogen-activated protein kinases (ERK, JNK, and p38MAPK) and PI3K signaling cascades control various physiological processes. In neuronal cells, recent studies have shown that these parallel cascades signal distinct forms of AMPA-sensitive glutamate receptor trafficking during experience-dependent synaptic plasticity and adaptive behavior. Interestingly, both hypo- and hyperactivation of Ras/ Rap signaling impair the capacity of synaptic plasticity, underscoring the importance of a "happy-medium" dynamic regulation of the signaling. Moreover, accumulating reports have linked various genetic defects that either up- or down-regulate Ras/Rap signaling with several mental disorders associated with learning disability (e.g., Alzheimer's disease, Angelman syndrome, autism, cardio-facio-cutaneous syndrome, Coffin-Lowry syndrome, Costello syndrome, Cowden and Bannayan-Riley-Ruvalcaba syndromes, fragile X syndrome, neurofibromatosis type 1, Noonan syndrome, schizophrenia, tuberous sclerosis, and X-linked mental retardation), highlighting the necessity of happy-medium dynamic regulation of Ras/Rap signaling in learning behavior. Thus, the recent advances in understanding of neuronal Ras/Rap signaling provide a useful guide for developing novel treatments for mental diseases.
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Affiliation(s)
- Ruth L Stornetta
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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46
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Abstract
Many metabolic pathways, including oxidative stress, PKC and the polyol pathway have been implicated in the development of diabetic retinopathy, but despite extensive research, its pathogenesis remains unclear. Recent studies have shown the role of a low-molecular-weight GTP-binding protein (H-Ras)-mediated signaling pathway in its development. The key effector protein of Ras function is a threonine/serine kinase-Raf kinase, and this kinase is involved in a variety of functions, including the cell cycle and proliferation and apoptosis. In animal models of diabetic retinopathy, Raf kinase is activated in the retina and its microvasculature. Activated Raf kinase is associated with increased apoptosis of retinal capillary cells, the process that precedes the development of retinal histopathology, and inhibition of Raf kinase ameliorates apoptosis. In clinical settings, inhibitors of Raf kinase have shown promising results in cancer treatment, and Raf kinase antisense oligonucleotides, iCo 007, is now in Phase II trial for macular edema, a chronic ocular disease associated with retinal neovascularization. Further elucidating the role of Raf kinase in diabetic retinopathy, and advances in the generation of antisense therapy for chronic diseases, should help test Raf antisense oligonucleotides for the treatment of this blinding complication that diabetic patients fear the most.
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Ye X, Carew TJ. Small G protein signaling in neuronal plasticity and memory formation: the specific role of ras family proteins. Neuron 2010; 68:340-61. [PMID: 21040840 PMCID: PMC3008420 DOI: 10.1016/j.neuron.2010.09.013] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2010] [Indexed: 01/04/2023]
Abstract
Small G proteins are an extensive family of proteins that bind and hydrolyze GTP. They are ubiquitous inside cells, regulating a wide range of cellular processes. Recently, many studies have examined the role of small G proteins, particularly the Ras family of G proteins, in memory formation. Once thought to be primarily involved in the transduction of a variety of extracellular signals during development, it is now clear that Ras family proteins also play critical roles in molecular processing underlying neuronal and behavioral plasticity. We here review a number of recent studies that explore how the signaling of Ras family proteins contributes to memory formation. Understanding these signaling processes is of fundamental importance both from a basic scientific perspective, with the goal of providing mechanistic insights into a critical aspect of cognitive behavior, and from a clinical perspective, with the goal of providing effective therapies for a range of disorders involving cognitive impairments.
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Affiliation(s)
- Xiaojing Ye
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92697, USA
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Anderton CR, Lou K, Weber PK, Hutcheon ID, Kraft ML. Correlated AFM and NanoSIMS imaging to probe cholesterol-induced changes in phase behavior and non-ideal mixing in ternary lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:307-15. [PMID: 20883665 DOI: 10.1016/j.bbamem.2010.09.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 09/09/2010] [Accepted: 09/20/2010] [Indexed: 12/13/2022]
Abstract
Cholesterol is believed to be an important component in compositionally distinct lipid domains in the cellular plasma membrane, which are referred to as lipid rafts. Insight into how cholesterol influences the interactions that contribute to plasma membrane organization can be acquired from model lipid membranes. Here we characterize the lipid mixing and phase behavior exhibited by (15)N-dilaurolyphosphatidycholine ((15)N-DLPC)/deuterated distearoylphosphatiylcholine (D(70)-DSPC) membranes with various amounts of cholesterol (0, 3, 7, 15 or 19mol%) at room temperature. The microstructures and compositions of individual membrane domains were determined by imaging the same membrane locations with both atomic force microscopy (AFM) and high-resolution secondary ion mass spectrometry (SIMS) performed with a Cameca NanoSIMS 50. As the cholesterol composition increased from 0 to 19mol%, the circular ordered domains became more elongated, and the amount of (15)N-DLPC in the gel-phase domains remained constant at 6-7mol%. Individual and micron-sized clusters of nanoscopic domains enriched in D(70)-DSPC were abundant in the 19mol% cholesterol membrane. AFM imaging showed that these lipid domains had irregular borders, indicating that they were gel-phase domains, and not non-ideally mixed lipid clusters or nanoscopic liquid-ordered domains.
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Affiliation(s)
- Christopher R Anderton
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Li H, Deng Y, Wu T, Subramanian S, Yu O. Misexpression of miR482, miR1512, and miR1515 increases soybean nodulation. PLANT PHYSIOLOGY 2010; 153:1759-70. [PMID: 20508137 PMCID: PMC2923892 DOI: 10.1104/pp.110.156950] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Accepted: 05/20/2010] [Indexed: 05/18/2023]
Abstract
MicroRNAs (miRNAs) are important regulators of plant growth and development. Previously, we identified a group of conserved and novel miRNA families from soybean (Glycine max) roots. Many of these miRNAs are specifically induced during soybean-Bradyrhizobium japonicum interactions. Here, we examined the gene expression levels of six families of novel miRNAs and investigated their functions in nodule development. We used northern-blot analyses to study the tissue specificity and time course of miRNA expression. Transgenic expression of miR482, miR1512, and miR1515 led to significant increases of nodule numbers, while root length, lateral root density, and the number of nodule primordia were not altered in all tested miRNA lines. We also found differential expression of these miRNAs in nonnodulating and supernodulating soybean mutants. The expression levels of 22 predicted target genes regulated by six novel miRNAs were studied by real-time polymerase chain reaction and quantitative real-time polymerase chain reaction. These results suggested that miRNAs play important roles in soybean nodule development.
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Affiliation(s)
| | | | | | | | - Oliver Yu
- Shanghai JiaoTong University, School of Agriculture and Biology, Shanghai 200240, China (H.L., T.W.); Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (Y.D., S.S., O.Y.); Plant Science Department, South Dakota State University, Brookings, South Dakota 57007 (S.S.)
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Weise K, Triola G, Janosch S, Waldmann H, Winter R. Visualizing association of lipidated signaling proteins in heterogeneous membranes−Partitioning into subdomains, lipid sorting, interfacial adsorption, and protein association. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1409-17. [DOI: 10.1016/j.bbamem.2009.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/05/2009] [Accepted: 12/08/2009] [Indexed: 01/05/2023]
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