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Stauffer PE, Brinkley J, Jacobson DA, Quaranta V, Tyson DR. Purinergic Ca 2+ Signaling as a Novel Mechanism of Drug Tolerance in BRAF-Mutant Melanoma. Cancers (Basel) 2024; 16:2426. [PMID: 39001489 PMCID: PMC11240618 DOI: 10.3390/cancers16132426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 06/27/2024] [Accepted: 06/27/2024] [Indexed: 07/16/2024] Open
Abstract
Drug tolerance is a major cause of relapse after cancer treatment. Despite intensive efforts, its molecular basis remains poorly understood, hampering actionable intervention. We report a previously unrecognized signaling mechanism supporting drug tolerance in BRAF-mutant melanoma treated with BRAF inhibitors that could be of general relevance to other cancers. Its key features are cell-intrinsic intracellular Ca2+ signaling initiated by P2X7 receptors (purinergic ligand-gated cation channels) and an enhanced ability for these Ca2+ signals to reactivate ERK1/2 in the drug-tolerant state. Extracellular ATP, virtually ubiquitous in living systems, is the ligand that can initiate Ca2+ spikes via P2X7 channels. ATP is abundant in the tumor microenvironment and is released by dying cells, ironically implicating treatment-initiated cancer cell death as a source of trophic stimuli that leads to ERK reactivation and drug tolerance. Such a mechanism immediately offers an explanation of the inevitable relapse after BRAFi treatment in BRAF-mutant melanoma and points to actionable strategies to overcome it.
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Affiliation(s)
- Philip E. Stauffer
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jordon Brinkley
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA;
| | - Vito Quaranta
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Darren R. Tyson
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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2
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Stauffer PE, Brinkley J, Jacobson D, Quaranta V, Tyson DR. Purinergic Ca 2+ signaling as a novel mechanism of drug tolerance in BRAF mutant melanoma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.03.565532. [PMID: 37961267 PMCID: PMC10635130 DOI: 10.1101/2023.11.03.565532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Drug tolerance is a major cause of relapse after cancer treatment. In spite of intensive efforts1-9, its molecular basis remains poorly understood, hampering actionable intervention. We report a previously unrecognized signaling mechanism supporting drug tolerance in BRAF-mutant melanoma treated with BRAF inhibitors that could be of general relevance to other cancers. Its key features are cell-intrinsic intracellular Ca2+ signaling initiated by P2X7 receptors (purinergic ligand-gated cation channels), and an enhanced ability for these Ca2+ signals to reactivate ERK1/2 in the drug-tolerant state. Extracellular ATP, virtually ubiquitous in living systems, is the ligand that can initiate Ca2+ spikes via P2X7 channels. ATP is abundant in the tumor microenvironment and is released by dying cells, ironically implicating treatment-initiated cancer cell death as a source of trophic stimuli that leads to ERK reactivation and drug tolerance. Such a mechanism immediately offers an explanation of the inevitable relapse after BRAFi treatment in BRAF-mutant melanoma, and points to actionable strategies to overcome it.
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Affiliation(s)
- Philip E Stauffer
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, USA
| | - Jordon Brinkley
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, USA
| | - David Jacobson
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, USA
| | - Vito Quaranta
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, USA
- Department of Biochemistry, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, USA
| | - Darren R Tyson
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, USA
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KRAP tethers IP 3 receptors to actin and licenses them to evoke cytosolic Ca 2+ signals. Nat Commun 2021; 12:4514. [PMID: 34301929 PMCID: PMC8302619 DOI: 10.1038/s41467-021-24739-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 07/01/2021] [Indexed: 02/06/2023] Open
Abstract
Regulation of IP3 receptors (IP3Rs) by IP3 and Ca2+ allows regenerative Ca2+ signals, the smallest being Ca2+ puffs, which arise from coordinated openings of a few clustered IP3Rs. Cells express thousands of mostly mobile IP3Rs, yet Ca2+ puffs occur at a few immobile IP3R clusters. By imaging cells with endogenous IP3Rs tagged with EGFP, we show that KRas-induced actin-interacting protein (KRAP) tethers IP3Rs to actin beneath the plasma membrane. Loss of KRAP abolishes Ca2+ puffs and the global increases in cytosolic Ca2+ concentration evoked by more intense stimulation. Over-expressing KRAP immobilizes additional IP3R clusters and results in more Ca2+ puffs and larger global Ca2+ signals. Endogenous KRAP determines which IP3Rs will respond: it tethers IP3R clusters to actin alongside sites where store-operated Ca2+ entry occurs, licenses IP3Rs to evoke Ca2+ puffs and global cytosolic Ca2+ signals, implicates the actin cytoskeleton in IP3R regulation and may allow local activation of Ca2+ entry.
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Eickelbeck D, Karapinar R, Jack A, Suess ST, Barzan R, Azimi Z, Surdin T, Grömmke M, Mark MD, Gerwert K, Jancke D, Wahle P, Spoida K, Herlitze S. CaMello-XR enables visualization and optogenetic control of G q/11 signals and receptor trafficking in GPCR-specific domains. Commun Biol 2019; 2:60. [PMID: 30793039 PMCID: PMC6376006 DOI: 10.1038/s42003-019-0292-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 01/09/2019] [Indexed: 12/20/2022] Open
Abstract
The signal specificity of G protein-coupled receptors (GPCRs) including serotonin receptors (5-HT-R) depends on the trafficking and localization of the GPCR within its subcellular signaling domain. Visualizing traffic-dependent GPCR signals in neurons is difficult, but important to understand the contribution of GPCRs to synaptic plasticity. We engineered CaMello (Ca2+-melanopsin-local-sensor) and CaMello-5HT2A for visualization of traffic-dependent Ca2+ signals in 5-HT2A-R domains. These constructs consist of the light-activated Gq/11 coupled melanopsin, mCherry and GCaMP6m for visualization of Ca2+ signals and receptor trafficking, and the 5-HT2A C-terminus for targeting into 5-HT2A-R domains. We show that the specific localization of the GPCR to its receptor domain drastically alters the dynamics and localization of the intracellular Ca2+ signals in different neuronal populations in vitro and in vivo. The CaMello method may be extended to every GPCR coupling to the Gq/11 pathway to help unravel new receptor-specific functions in respect to synaptic plasticity and GPCR localization. Dennis Eickelbeck et al. engineered light-activated constructs, CaMello and CaMello-5HT2A, which are targeted to the 5HT2A-R domains and enable visualization of calcium signals and receptor trafficking in response to activation. The reported CaMello tool could be applied to other GPCRs coupled to the Gq/11 signaling pathways which may shed light on mechanisms of GPCR localization and plasticity.
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Affiliation(s)
- Dennis Eickelbeck
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Raziye Karapinar
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Alexander Jack
- Developmental Neurobiology, ND6/72, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Sandra T Suess
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Ruxandra Barzan
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Zohre Azimi
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Tatjana Surdin
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Michelle Grömmke
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Melanie D Mark
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Klaus Gerwert
- Department of Biophysics, ND04/596, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Dirk Jancke
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Petra Wahle
- Developmental Neurobiology, ND6/72, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Katharina Spoida
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Stefan Herlitze
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany.
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Tong J, Qi Y, Wang X, Yu L, Su C, Xie W, Zhang J. Cell micropatterning reveals the modulatory effect of cell shape on proliferation through intracellular calcium transients. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2389-2401. [PMID: 28962833 DOI: 10.1016/j.bbamcr.2017.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 09/09/2017] [Accepted: 09/24/2017] [Indexed: 12/14/2022]
Abstract
The mechanism by which cell shape regulates the function of the cell is one of the most important biological issues, but it remains unclear. Here, we investigated the effect of the regulation of cell shape on proliferation by using a micropatterning approach to confine MC3T3-E1 cells into specific shapes. Our results show that the proliferation rate for rectangle-, triangle-, square- and circle-shaped osteoblasts increased sequentially and was related to the nuclear shape index (NSI) but not the cell shape index (CSI). Interestingly, intracellular calcium transients also displayed different patterns, with the number of Ca2+ peaks increasing with the NSI in shaped cells. Further causal investigation revealed that the gene expression levels of the inositol 1,4,5-triphosphate receptor 1 (IP3R1) and sarco/endoplasmic reticulum Ca2+-ATPase 2 (SERCA2), two major calcium cycling proteins in the endoplasmic reticulum (ER), were increased with an increase in NSI as a result of nuclear volume changes. Moreover, the down-regulation of IP3R1 and/or SERCA2 using shRNAs in circle-shaped or control osteoblasts resulted in changes in intracellular calcium transient patterns and cell proliferation rates towards that of smaller-NSI-shaped cells. Our results indicate that changes in cell shape changed nuclear morphology and then the gene expression of IP3R1 and SERCA2, which produced different intracellular calcium transient patterns. The patterns of intracellular calcium transients then determined the proliferation rate of the shaped osteoblasts.
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Affiliation(s)
- Jie Tong
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Ying Qi
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Xiangmiao Wang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Liyin Yu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Chang Su
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Wenjun Xie
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China
| | - Jianbao Zhang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, PR China.
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6
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Hidalgo C, Arias-Cavieres A. Calcium, Reactive Oxygen Species, and Synaptic Plasticity. Physiology (Bethesda) 2016; 31:201-15. [DOI: 10.1152/physiol.00038.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In this review article, we address how activity-dependent Ca2+ signaling is crucial for hippocampal synaptic/structural plasticity and discuss how changes in neuronal oxidative state affect Ca2+ signaling and synaptic plasticity. We also analyze current evidence indicating that oxidative stress and abnormal Ca2+ signaling contribute to age-related synaptic plasticity deterioration.
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Affiliation(s)
- Cecilia Hidalgo
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile; and
- Center of Molecular Studies of the Cell and Physiology and Biophysics Program, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Alejandra Arias-Cavieres
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile; and
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7
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Majewski L, Kuznicki J. SOCE in neurons: Signaling or just refilling? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1940-52. [DOI: 10.1016/j.bbamcr.2015.01.019] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 01/22/2015] [Accepted: 01/26/2015] [Indexed: 01/14/2023]
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Christo SN, Diener KR, Hayball JD. The functional contribution of calcium ion flux heterogeneity in T cells. Immunol Cell Biol 2015; 93:694-704. [PMID: 25823995 DOI: 10.1038/icb.2015.34] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/15/2015] [Accepted: 02/16/2015] [Indexed: 12/30/2022]
Abstract
The role of intracellular calcium ion oscillations in T-cell physiology is being increasingly appreciated by studies that describe how unique temporal and spatial calcium ion signatures can control different signalling pathways. Within this review, we provide detailed mechanisms of calcium ion oscillations, and emphasise the pivotal role that calcium signalling plays in directing crucial events pertaining to T-cell functionality. We also describe methods of calcium ion quantification, and take the opportunity to discuss how a deeper understanding of calcium signalling combined with new detection and quantification methodologies can be used to better design immunotherapies targeting T-cell responses.
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Affiliation(s)
- Susan N Christo
- Experimental Therapeutics Laboratory, Sansom Institute and Hanson Institute, School of Pharmacy and Medical Science, Division of Health Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Kerrilyn R Diener
- Experimental Therapeutics Laboratory, Sansom Institute and Hanson Institute, School of Pharmacy and Medical Science, Division of Health Sciences, University of South Australia, Adelaide, South Australia, Australia.,Robinson Research Institute, School of Paediatrics and Reproductive Health, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - John D Hayball
- Experimental Therapeutics Laboratory, Sansom Institute and Hanson Institute, School of Pharmacy and Medical Science, Division of Health Sciences, University of South Australia, Adelaide, South Australia, Australia.,School of Medicine, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia
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9
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Holz GG, Leech CA, Chepurny OG. New insights concerning the molecular basis for defective glucoregulation in soluble adenylyl cyclase knockout mice. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2593-600. [PMID: 24980705 DOI: 10.1016/j.bbadis.2014.06.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 01/09/2023]
Abstract
Recently published findings indicate that a knockout (KO) of soluble adenylyl cyclase (sAC, also known as AC-10) gene expression in mice leads to defective glucoregulation that is characterized by reduced pancreatic insulin secretion and reduced intraperitoneal glucose tolerance. Summarized here are current concepts regarding the molecular basis for this phenotype, with special emphasis on the potential role of sAC as a determinant of glucose-stimulated insulin secretion. Highlighted is new evidence that in pancreatic beta cells, oxidative glucose metabolism stimulates mitochondrial CO₂production that in turn generates bicarbonate ion (HCO(3)(-)). Since HCO(3)(-) binds to and directly stimulates the activity of sAC, we propose that glucose-stimulated cAMP production in beta cells is mediated not simply by transmembrane adenylyl cyclases (TMACs), but also by sAC. Based on evidence that sAC is expressed in mitochondria, there exists the possibility that beta-cell glucose metabolism is linked to mitochondrial cAMP production with consequent facilitation of oxidative phosphorylation. Since sAC is also expressed in the cytoplasm, sAC catalyzed cAMP production may activate cAMP sensors such as PKA and Epac2 to control ion channel function, intracellular Ca²⁺ handling, and Ca²⁺-dependent exocytosis. Thus, we propose that the existence of sAC in beta cells provides a new and unexpected explanation for previously reported actions of glucose metabolism to stimulate cAMP production. It seems possible that alterations of sAC activity might be of importance when evaluating new strategies for the treatment of type 2 diabetes (T2DM), or when evaluating why glucose metabolism fails to stimulate insulin secretion in patients diagnosed with T2DM. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- George G Holz
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA; Department of Pharmacology, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA.
| | - Colin A Leech
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA
| | - Oleg G Chepurny
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA
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10
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Wang Q, Wang Y, Fritz D, Rajshankar D, Downey GP, McCulloch CA. Interactions of the protein-tyrosine phosphatase-α with the focal adhesion targeting domain of focal adhesion kinase are involved in interleukin-1 signaling in fibroblasts. J Biol Chem 2014; 289:18427-41. [PMID: 24821720 DOI: 10.1074/jbc.m113.540294] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interleukin-1 (IL-1) signaling in fibroblasts is mediated through focal adhesions, organelles that are enriched with adaptor and cytoskeletal proteins that regulate signal transduction. We examined interactions of the focal adhesion kinase (FAK) with protein-tyrosine phosphatase-α (PTP-α) in IL-1 signaling. In wild type and FAK knock-out mouse embryonic fibroblasts, we found by immunoblotting, immunoprecipitation, immunostaining, and gene silencing that FAK is required for IL-1-mediated sequestration of PTPα to focal adhesions. Immunoprecipitation and pulldown assays of purified proteins demonstrated a direct interaction between FAK and PTPα, which was dependent on the FAT domain of FAK and by an intact membrane-proximal phosphatase domain of PTPα. Recruitment of PTPα to focal adhesions, IL-1-induced Ca(2+) release from the endoplasmic reticulum, ERK activation, and IL-6, MMP-3, and MMP-9 expression were all blocked in FAK knock-out fibroblasts. These processes were restored in FAK knock-out cells transfected with wild type FAK, FAT domain, and FRNK. Our data indicate that IL-1-induced signaling through focal adhesions involves interactions between the FAT domain of FAK and PTPα.
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Affiliation(s)
- Qin Wang
- From the Matrix Dynamics Group, University of Toronto, Toronto, Ontario M5S 3E2, Canada
| | - Yongqiang Wang
- From the Matrix Dynamics Group, University of Toronto, Toronto, Ontario M5S 3E2, Canada
| | - Dominik Fritz
- From the Matrix Dynamics Group, University of Toronto, Toronto, Ontario M5S 3E2, Canada
| | - Dhaarmini Rajshankar
- From the Matrix Dynamics Group, University of Toronto, Toronto, Ontario M5S 3E2, Canada
| | - Gregory P Downey
- the Division of Pulmonary, Sleep, and Critical Care Medicine, Department of Medicine, National Jewish Health, Denver, Colorado 80206, and the Division of Pulmonary Sciences and Critical Care Medicine, Departments of Medicine and Integrated Department of Immunology, University of Colorado, Aurora, Colorado 80045
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11
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Heiser JH, Schuwald AM, Sillani G, Ye L, Müller WE, Leuner K. TRPC6 channel-mediated neurite outgrowth in PC12 cells and hippocampal neurons involves activation of RAS/MEK/ERK, PI3K, and CAMKIV signaling. J Neurochem 2013; 127:303-13. [PMID: 23875811 DOI: 10.1111/jnc.12376] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 06/07/2013] [Accepted: 07/09/2013] [Indexed: 12/20/2022]
Abstract
The non-selective cationic transient receptor canonical 6 (TRPC6) channels are involved in synaptic plasticity changes ranging from dendritic growth, spine morphology changes and increase in excitatory synapses. We previously showed that the TRPC6 activator hyperforin, the active antidepressant component of St. John's wort, induces neuritic outgrowth and spine morphology changes in PC12 cells and hippocampal CA1 neurons. However, the signaling cascade that transmits the hyperforin-induced transient rise in intracellular calcium into neuritic outgrowth is not yet fully understood. Several signaling pathways are involved in calcium transient-mediated changes in synaptic plasticity, ranging from calmodulin-mediated Ras-induced signaling cascades comprising the mitogen-activated protein kinase, PI3K signal transduction pathways as well as Ca(2+) /calmodulin-dependent protein kinase II (CAMKII) and CAMKIV. We show that several mechanisms are involved in TRPC6-mediated synaptic plasticity changes in PC12 cells and primary hippocampal neurons. Influx of calcium via TRPC6 channels activates different pathways including Ras/mitogen-activated protein kinase/extracellular signal-regulated kinases, phosphatidylinositide 3-kinase/protein kinase B, and CAMKIV in both cell types, leading to cAMP-response element binding protein phosphorylation. These findings are interesting not only in terms of the downstream targets of TRPC6 channels but also because of their potential to facilitate further understanding of St. John's wort extract-mediated antidepressant activity. Alterations in synaptic plasticity are considered to play an important role in the pathogenesis of depression. Beside several other proteins, TRPC6 channels regulate synaptic plasticity. This study demonstrates that different pathways including Ras/MEK/ERK, PI3K/Akt, and CAMKIV are involved in the improvement of synaptic plasticity by the TRPC6 activator hyperforin, the antidepressant active constituent of St. John's wort extract.
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Affiliation(s)
- Jeanine H Heiser
- Institute of Pharmacology, Biocenter Niederursel, Goethe University, Frankfurt am Main, Germany
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12
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Traumatic noise activates Rho-family GTPases through transient cellular energy depletion. J Neurosci 2012; 32:12421-30. [PMID: 22956833 DOI: 10.1523/jneurosci.6381-11.2012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Small GTPases mediate transmembrane signaling and regulate the actin cytoskeleton in eukaryotic cells. Here, we characterize the auditory pathology of adult male CBA/J mice exposed to traumatic noise (2-20 kHz; 106 dB; 2 h). Loss of outer hair cells was evident 1 h after noise exposure in the basal region of the cochlea and spread apically with time, leading to permanent threshold shifts of 35, 60, and 65 dB at 8, 16, and 32 kHz. Several biochemical and molecular changes correlated temporally with the loss of cells. Immediately after exposure, the concentration of ATP decreased in cochlear tissue and reached a minimum after 1 h while the immunofluorescent signal for p-AMPKα significantly increased in sensory hair cells at that time. Levels of active Rac1 increased, whereas those of active RhoA decreased significantly 1 h after noise attaining a plateau at 1-3 h; the formation of a RhoA-p140mDia complex was consistent with an activation of Rho GTPase pathways. Also at 1-3 h after exposure, the caspase-independent cell death marker, Endo G, translocated to the nuclei of outer hair cells. Finally, experiments with the inner ear HEI-OC1 cell line demonstrated that the energy-depleting agent oligomycin enhanced both Rac1 activity and cell death. The sum of the results suggests that traumatic noise induces transient cellular ATP depletion and activates Rho GTPase pathways, leading to death of outer hair cells in the cochlea.
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Abstract
Ever since their discovery as cellular counterparts of viral oncogenes more than 25 years ago, much progress has been made in understanding the complex networks of signal transduction pathways activated by oncogenic Ras mutations in human cancers. The activity of Ras is regulated by nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), and much emphasis has been put into the biochemical and structural analysis of the Ras/GAP complex. The mechanisms by which GAPs catalyze Ras-GTP hydrolysis have been clarified and revealed that oncogenic Ras mutations confer resistance to GAPs and remain constitutively active. However, it is yet unclear how cells coordinate the large and divergent GAP protein family to promote Ras inactivation and ensure a certain biological response. Different domain arrangements in GAPs to create differential protein-protein and protein-lipid interactions are probably key factors determining the inactivation of the 3 Ras isoforms H-, K-, and N-Ras and their effector pathways. In recent years, in vitro as well as cell- and animal-based studies examining GAP activity, localization, interaction partners, and expression profiles have provided further insights into Ras inactivation and revealed characteristics of several GAPs to exert specific and distinct functions. This review aims to summarize knowledge on the cell biology of RasGAP proteins that potentially contributes to differential regulation of spatiotemporal Ras signaling.
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Affiliation(s)
- Thomas Grewal
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia
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14
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Dai Y, Walker SA, de Vet E, Cook S, Welch HCE, Lockyer PJ. Ca2+-dependent monomer and dimer formation switches CAPRI Protein between Ras GTPase-activating protein (GAP) and RapGAP activities. J Biol Chem 2011; 286:19905-16. [PMID: 21460216 DOI: 10.1074/jbc.m110.201301] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CAPRI is a member of the GAP1 family of GTPase-activating proteins (GAPs) for small G proteins. It is known to function as an amplitude sensor for intracellular Ca(2+) levels stimulated by extracellular signals and has a catalytic domain with dual RasGAP and RapGAP activities. Here, we have investigated the mechanism that switches CAPRI between its two GAP activities. We demonstrate that CAPRI forms homodimers in vitro and in vivo in a Ca(2+)-dependent manner. The site required for dimerization was pinpointed by deletion and point mutations to a helix motif that forms a hydrophobic face in the extreme C-terminal tail of the CAPRI protein. Deletion of this helix motif abolished dimer formation but did not affect translocation of CAPRI to the plasma membrane upon cell stimulation with histamine. We found that dimeric and monomeric CAPRI coexist in cells and that the ratio of dimeric to monomeric CAPRI increases upon cell stimulation with histamine. Free Ca(2+) at physiologically relevant concentrations was both necessary and sufficient for dimer formation. Importantly, the monomeric and dimeric forms of CAPRI exhibited differential GAP activities in vivo; the wild-type form of CAPRI had stronger RapGAP activity than RasGAP activity, whereas a monomeric CAPRI mutant showed stronger RasGAP than RapGAP activity. These results demonstrate that CAPRI switches between its dual GAP roles by forming monomers or homodimers through a process regulated by Ca(2+). We propose that Ca(2+)-dependent dimerization of CAPRI may serve to coordinate Ras and Rap1 signaling pathways.
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Affiliation(s)
- Yanfeng Dai
- Laboratory of Molecular Signalling, The Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom.
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15
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Yoshiki S, Matsunaga-Udagawa R, Aoki K, Kamioka Y, Kiyokawa E, Matsuda M. Ras and calcium signaling pathways converge at Raf1 via the Shoc2 scaffold protein. Mol Biol Cell 2010; 21:1088-96. [PMID: 20071468 PMCID: PMC2836960 DOI: 10.1091/mbc.e09-06-0455] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Activation of Raf1 at the plasma membrane requires not only Ras activation but also an increase in Ca2+ concentration or inhibition of calmodulin. The Ca2+-dependent activation of Raf1 is abrogated by knockdown of Shoc2. We show that the Shoc2 scaffold protein modulates Ras-dependent Raf1 activation in a Ca2+- and calmodulin-dependent manner. Situated downstream of Ras is a key signaling molecule, Raf1. Increase in Ca2+ concentration has been shown to modulate the Ras-dependent activation of Raf1; however, the mechanism underlying this effect remains elusive. Here, to characterize the role of Ca2+ in Ras signaling to Raf1, we used a synthetic guanine nucleotide exchange factor (GEF) for Ras, eGRF. In HeLa cells expressing eGRF, Ras was activated by the cAMP analogue 007 as efficiently as by epidermal growth factor (EGF), whereas the activation of Raf1, MEK, and ERK by 007 was about half of that by EGF. Using a biosensor based on fluorescence resonance energy transfer, it was found that activation of Raf1 at the plasma membrane required not only Ras activation but also an increase in Ca2+ concentration or inhibition of calmodulin. Furthermore, the Ca2+-dependent activation of Raf1 was found to be abrogated by knockdown of Shoc2, a scaffold protein that binds both Ras and Raf1. These observations indicated that the Shoc2 scaffold protein modulates Ras-dependent Raf1 activation in a Ca2+- and calmodulin-dependent manner.
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Affiliation(s)
- Sayaka Yoshiki
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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16
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Sorgato MC, Peggion C, Bertoli A. Is, indeed, the prion protein a Harlequin servant of "many" masters? Prion 2009; 3:202-5. [PMID: 19887913 DOI: 10.4161/pri.3.4.10012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Tens of putative interacting partners of the cellular prion protein (PrP(C)) have been identified, yet the physiologic role of PrP(C) remains unclear. For the first time, however, a recent paper has demonstrated that the absence of PrP(C) produces a lethal phenotype. Starting from this evidence, here we discuss the validity of past and more recent literature supporting that, as part of protein platforms at the cell surface, PrP(C) may bridge extracellular matrix molecules and/or membrane proteins to intracellular signaling pathways.
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Affiliation(s)
- M Catia Sorgato
- Department of Biological Chemistry and CNR Institute of Neuroscience, University of Padova, Padova, Italy
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17
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Vilá de Muga S, Timpson P, Cubells L, Evans R, Hayes TE, Rentero C, Hegemann A, Reverter M, Leschner J, Pol A, Tebar F, Daly RJ, Enrich C, Grewal T. Annexin A6 inhibits Ras signalling in breast cancer cells. Oncogene 2008; 28:363-77. [PMID: 18850003 DOI: 10.1038/onc.2008.386] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Overexpression of epidermal growth factor receptor (EGFR) is associated with enhanced activation of wild-type (hyperactive) Ras in breast cancer. Little is known about the regulation of Ras inactivation and GTPase-activating proteins (GAPs), such as p120GAP, in cells with hyperactive Ras. Recently, we showed that in EGFR-overexpressing A431 cells, which lack endogenous Annexin A6 (AnxA6), ectopic expression of AnxA6 stimulates membrane recruitment of p120GAP to modulate Ras signalling. We now demonstrate that, AnxA6 is downregulated in a number of EGFR-overexpressing and estrogen receptor (ER)-negative breast cancer cells. In these cells, AnxA6 overexpression promotes Ca(2+)- and EGF-inducible membrane targeting of p120GAP. In ER-negative MDA-MB-436 cells, overexpression of p120GAP, but not CAPRI or a p120GAP mutant lacking the AnxA6-binding domain inhibits Ras/MAPK activity. AnxA6 knockdown in MDA-MB-436 increases Ras activity and cell proliferation in anchorage-independent growth assays. Furthermore, AnxA6 co-immunoprecipitates with H-Ras in a Ca(2+)- and EGF-inducible manner and fluorescence resonance energy transfer (FRET) microscopy confirmed that AnxA6 is in close proximity of active (G12V), but not inactive (S17N) H-Ras. Thus, association of AnxA6 with H-Ras-containing protein complexes may contribute to regulate p120GAP/Ras assembly in EGFR-overexpressing and ER-negative breast cancer cells.
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Affiliation(s)
- S Vilá de Muga
- Departament de Biologia Cellular, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
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18
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Tadross MR, Dick IE, Yue DT. Mechanism of local and global Ca2+ sensing by calmodulin in complex with a Ca2+ channel. Cell 2008; 133:1228-40. [PMID: 18585356 DOI: 10.1016/j.cell.2008.05.025] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 02/22/2008] [Accepted: 05/16/2008] [Indexed: 12/29/2022]
Abstract
Calmodulin (CaM) in complex with Ca(2+) channels constitutes a prototype for Ca(2+) sensors that are intimately colocalized with Ca(2+) sources. The C-lobe of CaM senses local, large Ca(2+) oscillations due to Ca(2+) influx from the host channel, and the N-lobe senses global, albeit diminutive Ca(2+) changes arising from distant sources. Though biologically essential, the mechanism underlying global Ca(2+) sensing has remained unknown. Here, we advance a theory of how global selectivity arises, and we experimentally validate this proposal with methodologies enabling millisecond control of Ca(2+) oscillations seen by the CaM/channel complex. We find that global selectivity arises from rapid Ca(2+) release from CaM combined with greater affinity of the channel for Ca(2+)-free versus Ca(2+)-bound CaM. The emergence of complex decoding properties from the juxtaposition of common elements, and the techniques developed herein, promise generalization to numerous molecules residing near Ca(2+) sources.
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Affiliation(s)
- Michael R Tadross
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, USA
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19
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Hidalgo C, Donoso P. Crosstalk between calcium and redox signaling: from molecular mechanisms to health implications. Antioxid Redox Signal 2008; 10:1275-312. [PMID: 18377233 DOI: 10.1089/ars.2007.1886] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Studies done many years ago established unequivocally the key role of calcium as a universal second messenger. In contrast, the second messenger roles of reactive oxygen and nitrogen species have emerged only recently. Therefore, their contributions to physiological cell signaling pathways have not yet become universally accepted, and many biological researchers still regard them only as cellular noxious agents. Furthermore, it is becoming increasingly apparent that there are significant interactions between calcium and redox species, and that these interactions modify a variety of proteins that participate in signaling transduction pathways and in other fundamental cellular functions that determine cell life or death. This review article addresses first the central aspects of calcium and redox signaling pathways in animal cells, and continues with the molecular mechanisms that underlie crosstalk between calcium and redox signals under a number of physiological or pathological conditions. To conclude, the review focuses on conditions that, by promoting cellular oxidative stress, lead to the generation of abnormal calcium signals, and how this calcium imbalance may cause a variety of human diseases including, in particular, degenerative diseases of the central nervous system and cardiac pathologies.
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Affiliation(s)
- Cecilia Hidalgo
- Centro FONDAP de Estudios Moleculares de la Célula and Programa de Biología Molecular y Celular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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20
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Ren JG, Li Z, Sacks DB. IQGAP1 integrates Ca2+/calmodulin and B-Raf signaling. J Biol Chem 2008; 283:22972-82. [PMID: 18567582 DOI: 10.1074/jbc.m804626200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ca(2+) and calmodulin modulate numerous cellular functions, ranging from muscle contraction to the cell cycle. Accumulating evidence indicates that Ca(2+) and calmodulin regulate the MAPK signaling pathway at multiple positions in the cascade, but the molecular mechanism underlying these observations is poorly defined. We previously documented that IQGAP1 is a scaffold in the MAPK cascade. IQGAP1 binds to and regulates the activities of ERK, MEK, and B-Raf. Here we demonstrate that IQGAP1 integrates Ca(2+) and calmodulin with B-Raf signaling. In vitro analysis reveals that Ca(2+) promotes the direct binding of IQGAP1 to B-Raf. This interaction is inhibited by calmodulin in a Ca(2+)-regulated manner. Epidermal growth factor (EGF) is unable to stimulate B-Raf activity in fibroblasts treated with the Ca(2+) ionophore A23187. In contrast, chelation of intracellular free Ca(2+) concentrations ([Ca(2+)](i)) significantly enhances EGF-stimulated B-Raf activity, an effect that is dependent on IQGAP1. Incubation of cells with EGF augments the association of B-Raf with IQGAP1. Moreover, Ca(2+) regulates the association of B-Raf with IQGAP1 in cells. Increasing [Ca(2+)](i) with Ca(2+) ionophores significantly reduces co-immunoprecipitation of B-Raf and IQGAP1, whereas chelation of Ca(2+) enhances the interaction. Consistent with these findings, increasing and decreasing [Ca(2+)](i) increase and decrease, respectively, co-immunoprecipitation of calmodulin with IQGAP1. Collectively, our data identify a previously unrecognized mechanism in which the scaffold protein IQGAP1 couples Ca(2+) and calmodulin signaling to B-Raf function.
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Affiliation(s)
- Jian-Guo Ren
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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21
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Abstract
Experimental studies have demonstrated that Ca(2+)-regulated proteins are sensitive to the frequency of Ca(2+) oscillations, and several mathematical models for specific proteins have provided insight into the mechanisms involved. Because of the large number of Ca(2+)-regulated proteins in signal transduction, metabolism and gene expression, it is desirable to establish in general terms which molecular properties shape the response to oscillatory Ca(2+) signals. Here we address this question by analyzing in detail a model of a prototypical Ca(2+)-decoding module, consisting of a target protein whose activity is controlled by a Ca(2+)-activated kinase and the counteracting phosphatase. We show that this module can decode the frequency of Ca(2+) oscillations, at constant average Ca(2+) signal, provided that the Ca(2+) spikes are narrow and the oscillation frequency is sufficiently low--of the order of the phosphatase rate constant or below. Moreover, Ca(2+) oscillations activate the target more efficiently than a constant signal when Ca(2+) is bound cooperatively and with low affinity. Thus, the rate constants and the Ca(2+) affinities of the target-modifying enzymes can be tuned in such a way that the module responds optimally to Ca(2+) spikes of a certain amplitude and frequency. Frequency sensitivity is further enhanced when the limited duration of the external stimulus driving Ca(2+) signaling is accounted for. Thus, our study identifies molecular parameters that may be involved in establishing the specificity of cellular responses downstream of Ca(2+) oscillations.
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22
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Eisenberg S, Henis YI. Interactions of Ras proteins with the plasma membrane and their roles in signaling. Cell Signal 2007; 20:31-9. [PMID: 17888630 DOI: 10.1016/j.cellsig.2007.07.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Accepted: 07/18/2007] [Indexed: 12/21/2022]
Abstract
The complex dynamic structure of the plasma membrane plays critical roles in cellular signaling; interactions with the membrane lipid milieu, spatial segregation within and between cellular membranes and/or targeting to specific membrane-associated scaffolds are intimately involved in many signal transduction pathways. In this review, we focus on the membrane interactions of Ras proteins. These small GTPases play central roles in the regulation of cell growth and proliferation, and their excessive activation is commonly encountered in human tumors. Ras proteins associate with the membrane continuously via C-terminal lipidation and additional interactions in both their inactive and active forms; this association, as well as the targeting of specific Ras isoforms to plasma membrane microdomains and to intracellular organelles, have recently been implicated in Ras signaling and oncogenic potential. We discuss biochemical and biophysical evidence for the roles of specific domains of Ras proteins in mediating their association with the plasma membrane, and consider the potential effects of lateral segregation and interactions with membrane-associated protein assemblies on the signaling outcomes.
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Affiliation(s)
- Sharon Eisenberg
- Department of Neurobiochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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23
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Jin H, Wang X, Ying J, Wong AHY, Cui Y, Srivastava G, Shen ZY, Li EM, Zhang Q, Jin J, Kupzig S, Chan ATC, Cullen PJ, Tao Q. Epigenetic silencing of a Ca(2+)-regulated Ras GTPase-activating protein RASAL defines a new mechanism of Ras activation in human cancers. Proc Natl Acad Sci U S A 2007; 104:12353-8. [PMID: 17640920 PMCID: PMC1941473 DOI: 10.1073/pnas.0700153104] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Ras has achieved notoriety as an oncogene aberrantly activated in multiple human tumors. Approximately 30% of all human tumors express an oncogenic form of this GTPase that is locked in an active conformation as a result of being insensitive to Ras GTPase-activating proteins (GAPs), proteins that normally regulate the inactivation of Ras by enhancing its intrinsic GTPase activity. Besides oncogenic mutations in Ras, signaling by wild-type Ras is also frequently deregulated in tumors through aberrant coupling to activated cell surface receptors. This indicates that alternative mechanisms of aberrant wild-type Ras activation may be involved in tumorigenesis. Here, we describe another mechanism through which aberrant Ras activation is achieved in human cancers. We have established that Ras GTPase-activating-like protein (RASAL), a Ca(2+)-regulated Ras GAP that decodes the frequency of Ca(2+) oscillations, is silenced through CpG methylation in multiple tumors. With the finding that ectopic expression of catalytically active RASAL leads to growth inhibition of these tumor cells by Ras inactivation, we have provided evidence that epigenetically silencing of this Ras GAP represents a mechanism of aberrant Ras activation in certain cancers. Our demonstration that RASAL constitutes a tumor suppressor gene has therefore further emphasized the importance of Ca(2+) in the regulation of Ras signaling and has established that deregulation of this pathway is an important step in Ras-mediated tumorigenesis.
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Affiliation(s)
- Hongchuan Jin
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
| | - Xian Wang
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
| | - Jianming Ying
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
| | - Ada H. Y. Wong
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
| | - Yan Cui
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
| | | | - Zhong-Ying Shen
- Shantou University Medical College/Chinese University of Hong Kong Joint Epigenetics Group, Shantou University Medical College, Shantou 515041, China
| | - En-Min Li
- Shantou University Medical College/Chinese University of Hong Kong Joint Epigenetics Group, Shantou University Medical College, Shantou 515041, China
| | - Qian Zhang
- Department of Urology, Peking University First Hospital and Institute of Urology, Beijing 100034, China; and
| | - Jie Jin
- Department of Urology, Peking University First Hospital and Institute of Urology, Beijing 100034, China; and
| | - Sabine Kupzig
- The Henry Wellcome Integrated Signalling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Anthony T. C. Chan
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
| | - Peter J. Cullen
- The Henry Wellcome Integrated Signalling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
- To whom correspondence may be addressed. E-mail: or
| | - Qian Tao
- *Cancer Epigenetics Laboratory, State Key Laboratory in Oncology in South China, Sir Y. K. Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong
- Shantou University Medical College/Chinese University of Hong Kong Joint Epigenetics Group, Shantou University Medical College, Shantou 515041, China
- To whom correspondence may be addressed. E-mail: or
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24
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Lloyd-Burton SM, Yu JCH, Irvine RF, Schell MJ. Regulation of Inositol 1,4,5-Trisphosphate 3-Kinases by Calcium and Localization in Cells. J Biol Chem 2007; 282:9526-9535. [PMID: 17284449 DOI: 10.1074/jbc.m610253200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) 3-kinases (IP(3)Ks) are a group of calmodulin-regulated inositol polyphosphate kinases (IPKs) that convert the second messenger Ins(1,4,5)P(3) into inositol 1,3,4,5-tetrakisphosphate. However, what they contribute to the complexities of Ca(2+) signaling, and how, is still not fully understood. In this study, we have used a simple Ca(2+) imaging assay to compare the abilities of various Ins (1,4,5)P(3)-metabolizing enzymes to regulate a maximal histamine-stimulated Ca(2+) signal in HeLa cells. Using transient transfection, we overexpressed green fluorescent protein-tagged versions of all three mammalian IP(3)K isoforms, including mutants with disrupted cellular localization or calmodulin regulation, and then imaged the Ca(2+) release stimulated by 100 microm histamine. Both localization to the F-actin cytoskeleton and calmodulin regulation enhance the efficiency of mammalian IP(3)Ks to dampen the Ins (1,4,5)P(3)-mediated Ca(2+) signals. We also compared the effects of the these IP(3)Ks with other enzymes that metabolize Ins(1,4,5)P(3), including the Type I Ins(1,4,5)P(3) 5-phosphatase, in both membrane-targeted and soluble forms, the human inositol polyphosphate multikinase, and the two isoforms of IP(3)K found in Drosophila. All reduce the Ca(2+) signal but to varying degrees. We demonstrate that the activity of only one of two IP(3)K isoforms from Drosophila is positively regulated by calmodulin and that neither isoform associates with the cytoskeleton. Together the data suggest that IP(3)Ks evolved to regulate kinetic and spatial aspects of Ins (1,4,5)P(3) signals in increasingly complex ways in vertebrates, consistent with their probable roles in the regulation of higher brain and immune function.
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Affiliation(s)
- Samantha M Lloyd-Burton
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Jowie C H Yu
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Robin F Irvine
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
| | - Michael J Schell
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
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25
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Grewal T, Enrich C. Molecular mechanisms involved in Ras inactivation: the annexin A6–p120GAP complex. Bioessays 2006; 28:1211-20. [PMID: 17120209 DOI: 10.1002/bies.20503] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In mammalian cells, a complex network of signaling pathways tightly regulates a variety of cellular processes, such as proliferation and differentiation. New insights from one of the most-important signaling cascades involved in oncogenesis, the Ras-Raf-MAPK pathway, suggest that the subcellular localisation and assembly of signaling modules of this pathway is crucial to control the biological response. This commonly requires membrane targeting events that are mediated by adaptor/scaffold proteins. Of particular interest is the translocation and complex formation of GTPase-activating proteins (GAPs), such as p120GAP, at the plasma membrane to inactivate Ras. Recent studies indicate that one member of the annexin family, annexin A6 acts as a targeting protein for p120GAP. This review discusses how annexin A6 modulates the involvement of negative regulators of the Ras-Raf-MAPK pathway contributing to Ras inactivation.
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Affiliation(s)
- Thomas Grewal
- Centre for Immunology, St. Vincent's Hospital, University of New South Wales, Sydney, Australia.
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