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Horvath JD, Casas M, Kutchukian C, Sánchez SC, Pergande MR, Cologna SM, Simó S, Dixon RE, Dickson EJ. α-Synuclein-dependent increases in PIP5K1γ drive inositol signaling to promote neurotoxicity. Cell Rep 2023; 42:113244. [PMID: 37838947 PMCID: PMC11010634 DOI: 10.1016/j.celrep.2023.113244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 08/09/2023] [Accepted: 09/25/2023] [Indexed: 10/17/2023] Open
Abstract
Anomalous aggregation of α-synuclein (α-Syn) is a pathological hallmark of many degenerative synucleinopathies including Lewy body dementia (LBD) and Parkinson's disease (PD). Despite its strong link to disease, the precise molecular mechanisms that link α-Syn aggregation to neurodegeneration have yet to be elucidated. Here, we find that elevated α-Syn leads to an increase in the plasma membrane (PM) phosphoinositide PI(4,5)P2, which precipitates α-Syn aggregation and drives toxic increases in mitochondrial Ca2+ and reactive oxygen species leading to neuronal death. Upstream of this toxic signaling pathway is PIP5K1γ, whose abundance and localization is enhanced at the PM by α-Syn-dependent increases in ARF6. Selective inhibition of PIP5K1γ or knockout of ARF6 in neurons rescues α-Syn aggregation and cellular phenotypes of toxicity. Collectively, our data suggest that modulation of phosphoinositide metabolism may be a therapeutic target to slow neurodegeneration for PD and other related neurodegenerative disorders.
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Affiliation(s)
- Jonathan D Horvath
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Maria Casas
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Candice Kutchukian
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Sara Creus Sánchez
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | | | | | - Sergi Simó
- Department of Cell Biology and Human Anatomy, University of California, Davis, Davis, CA 95616, USA
| | - Rose E Dixon
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA.
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2
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Llorente A, Loughran RM, Emerling BM. Targeting phosphoinositide signaling in cancer: relevant techniques to study lipids and novel avenues for therapeutic intervention. Front Cell Dev Biol 2023; 11:1297355. [PMID: 37954209 PMCID: PMC10634348 DOI: 10.3389/fcell.2023.1297355] [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: 09/19/2023] [Accepted: 10/12/2023] [Indexed: 11/14/2023] Open
Abstract
Phosphoinositides serve as essential players in numerous biological activities and are critical for overall cellular function. Due to their complex chemical structures, localization, and low abundance, current challenges in the phosphoinositide field include the accurate measurement and identification of specific variants, particularly those with acyl chains. Researchers are intensively developing innovative techniques and approaches to address these challenges and advance our understanding of the impact of phosphoinositide signaling on cellular biology. This article provides an overview of recent advances in the study of phosphoinositides, including mass spectrometry, lipid biosensors, and real-time activity assays using fluorometric sensors. These methodologies have proven instrumental for a comprehensive exploration of the cellular distribution and dynamics of phosphoinositides and have shed light on the growing significance of these lipids in human health and various pathological processes, including cancer. To illustrate the importance of phosphoinositide signaling in disease, this perspective also highlights the role of a family of lipid kinases named phosphatidylinositol 5-phosphate 4-kinases (PI5P4Ks), which have recently emerged as exciting therapeutic targets for cancer treatment. The ongoing exploration of phosphoinositide signaling not only deepens our understanding of cellular biology but also holds promise for novel interventions in cancer therapy.
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Affiliation(s)
| | | | - Brooke M. Emerling
- Cancer Metabolism and Microenvironment Program, Sanford Burnham Prebys, La Jolla, CA, United States
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3
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Thallmair V, Schultz L, Evers S, Jolie T, Goecke C, Leitner MG, Thallmair S, Oliver D. Localization of the tubby domain, a PI(4,5)P2 biosensor, to E-Syt3-rich endoplasmic reticulum-plasma membrane junctions. J Cell Sci 2023; 136:jcs260848. [PMID: 37401342 PMCID: PMC10445746 DOI: 10.1242/jcs.260848] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 06/26/2023] [Indexed: 07/05/2023] Open
Abstract
The phospholipid phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] acts as a signaling lipid at the plasma membrane (PM) with pleiotropic regulatory actions on multiple cellular processes. Signaling specificity might result from spatiotemporal compartmentalization of the lipid and from combinatorial binding of PI(4,5)P2 effector proteins to additional membrane components. Here, we analyzed the spatial distribution of tubbyCT, a paradigmatic PI(4,5)P2-binding domain, in live mammalian cells by total internal reflection fluorescence (TIRF) microscopy and molecular dynamics simulations. We found that unlike other well-characterized PI(4,5)P2 recognition domains, tubbyCT segregates into distinct domains within the PM. TubbyCT enrichment occurred at contact sites between PM and endoplasmic reticulum (ER) (i.e. at ER-PM junctions) as shown by colocalization with ER-PM markers. Localization to these sites was mediated in a combinatorial manner by binding to PI(4,5)P2 and by interaction with a cytosolic domain of extended synaptotagmin 3 (E-Syt3), but not other E-Syt isoforms. Selective localization to these structures suggests that tubbyCT is a novel selective reporter for a ER-PM junctional pool of PI(4,5)P2. Finally, we found that association with ER-PM junctions is a conserved feature of tubby-like proteins (TULPs), suggesting an as-yet-unknown function of TULPs.
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Affiliation(s)
- Veronika Thallmair
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps UniversityMarburg, 35037 Marburg, Germany
| | - Lea Schultz
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
| | - Saskia Evers
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
| | - Theresa Jolie
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
| | - Christian Goecke
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
| | - Michael G. Leitner
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH&Co.KG, Birkendorfer Str. 65, 88400 Biberach an der Riß, Germany
| | - Sebastian Thallmair
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany
- Groningen Biomolecular Sciences and Biotechnology Institute and The Zernike Institute for Advanced Material, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037 Marburg, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps UniversityMarburg, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, 35032 Marburg, Germany
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4
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Abstract
Lipids are key components of all organisms. We are well educated in their use as fuel and their essential role to form membranes. We also know much about their biosynthesis and metabolism. We are also aware that most lipids have signaling character meaning that a change in their concentration or location constitutes a signal that helps a living cell to respond to changes in the environment or to fulfill its specific function ranging from secretion to cell division. What is much less understood is how lipids change location in cells over time and what other biomolecules they interact with at each stage of their lifetime. Due to the large number of often quite similar lipid species and the sometimes very short lifetime of signaling lipids, we need highly specific tools to manipulate and visualize lipids and lipid-protein interactions. If successfully applied, these tools provide fabulous opportunities for discovery.In this Account, I summarize the development of synthetic tools from our lab that were designed to address crucial properties that allow them to function as tools in live cell experiments. Techniques to change the concentration of lipids by adding a small molecule or by light are described and complemented by examples of biological findings made when applying the tools. This ranges from chemical dimerizer-based systems to synthetic "caged" lipid derivatives. Furthermore, I discuss the problem of locating a lipid in an intact cell. Synthetic molecular probes are described that help to unravel the lipid location and to determine their binding proteins. These location studies require in-cell lipid tagging by click chemistry, photo-cross-linking to prevent further movement and the "caging" groups to avoid premature metabolism. The combination of these many technical features in a single tool allows for the analysis of not only lipid fluxes through metabolism but also lipid transport from one membrane to another as well as revealing the lipid interactome in a cell-dependent manner. This latter point is crucial because with these multifunctional tools in combination with lipidomics we can now address differences in healthy versus diseased cells and ultimately find the changes that are essential for disease development and new therapeutics that prevent these changes.
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Affiliation(s)
- Carsten Schultz
- Department of Chemical Physiology and
Biochemistry, Oregon Health & Science
University, Portland, Oregon 97239, United States
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5
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Two-step structural changes in M3 muscarinic receptor activation rely on the coupled G q protein cycle. Nat Commun 2023; 14:1276. [PMID: 36882424 PMCID: PMC9992711 DOI: 10.1038/s41467-023-36911-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 02/23/2023] [Indexed: 03/09/2023] Open
Abstract
G protein-coupled receptors (GPCRs) regulate diverse intracellular signaling pathways through the activation of heterotrimeric G proteins. However, the effects of the sequential activation-deactivation cycle of G protein on the conformational changes of GPCRs remains unknown. By developing a Förster resonance energy transfer (FRET) tool for human M3 muscarinic receptor (hM3R), we find that a single-receptor FRET probe can display the consecutive structural conversion of a receptor by G protein cycle. Our results reveal that the G protein activation evokes a two-step change in the hM3R structure, including the fast step mediated by Gq protein binding and the subsequent slower step mediated by the physical separation of the Gαq and Gβγ subunits. We also find that the separated Gαq-GTP forms a stable complex with the ligand-activated hM3R and phospholipase Cβ. In sum, the present study uncovers the real-time conformational dynamics of innate hM3R during the downstream Gq protein cycle.
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Cabral-Dias R, Antonescu CN. Control of phosphatidylinositol-3-kinase signaling by nanoscale membrane compartmentalization. Bioessays 2023; 45:e2200196. [PMID: 36567275 DOI: 10.1002/bies.202200196] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 09/12/2022] [Accepted: 12/13/2022] [Indexed: 12/27/2022]
Abstract
Phosphatidylinositol-3-kinases (PI3Ks) are lipid kinases that produce 3-phosphorylated derivatives of phosphatidylinositol upon activation by various cues. These 3-phosphorylated lipids bind to various protein effectors to control many cellular functions. Lipid phosphatases such as phosphatase and tensin homolog (PTEN) terminate PI3K-derived signals and are critical to ensure appropriate signaling outcomes. Many lines of evidence indicate that PI3Ks and PTEN, as well as some specific lipid effectors are highly compartmentalized, either in plasma membrane nanodomains or in endosomal compartments. We examine the evidence for specific recruitment of PI3Ks, PTEN, and other related enzymes to membrane nanodomains and endocytic compartments. We then examine the hypothesis that scaffolding of the sources (PI3Ks), terminators (PTEN), and effectors of these lipid signals with a common plasma membrane nanodomain may achieve highly localized lipid signaling and ensure selective activation of specific effectors. This highlights the importance of spatial regulation of PI3K signaling in various physiological and disease contexts.
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Affiliation(s)
- Rebecca Cabral-Dias
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Costin N Antonescu
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Toronto Metropolitan University, Toronto, Ontario, Canada
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7
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Borges-Araújo L, Monteiro ME, Mil-Homens D, Bernardes N, Sarmento MJ, Coutinho A, Prieto M, Fernandes F. Impact of Ca 2+-Induced PI(4,5)P 2 Clusters on PH-YFP Organization and Protein-Protein Interactions. Biomolecules 2022; 12:912. [PMID: 35883468 PMCID: PMC9312469 DOI: 10.3390/biom12070912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
Despite its low abundance, phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a key modulator of membrane-associated signaling events in eukaryotic cells. Temporal and spatial regulation of PI(4,5)P2 concentration can achieve localized increases in the levels of this lipid, which are crucial for the activation or recruitment of peripheral proteins to the plasma membrane. The recent observation of the dramatic impact of physiological divalent cation concentrations on PI(4,5)P2 clustering, suggests that protein anchoring to the plasma membrane through PI(4,5)P2 is likely not defined solely by a simple (monomeric PI(4,5)P2)/(protein bound PI(4,5)P2) equilibrium, but instead depends on complex protein interactions with PI(4,5)P2 clusters. The insertion of PI(4,5)P2-binding proteins within these clusters can putatively modulate protein-protein interactions in the membrane, but the relevance of such effects is largely unknown. In this work, we characterized the impact of Ca2+ on the organization and protein-protein interactions of PI(4,5)P2-binding proteins. We show that, in giant unilamellar vesicles presenting PI(4,5)P2, the membrane diffusion properties of pleckstrin homology (PH) domains tagged with a yellow fluorescent protein (YFP) are affected by the presence of Ca2+, suggesting direct interactions between the protein and PI(4,5)P2 clusters. Importantly, PH-YFP is found to dimerize in the membrane in the absence of Ca2+. This oligomerization is inhibited in the presence of physiological concentrations of the divalent cation. These results confirm that cation-dependent PI(4,5)P2 clustering promotes interactions between PI(4,5)P2-binding proteins and has the potential to dramatically influence the organization and downstream interactions of PI(4,5)P2-binding proteins in the plasma membrane.
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Affiliation(s)
- Luís Borges-Araújo
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Marina E. Monteiro
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (M.E.M.); (M.J.S.)
| | - Dalila Mil-Homens
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Nuno Bernardes
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Maria J. Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (M.E.M.); (M.J.S.)
- Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Avenida Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Ana Coutinho
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
- Departamento de Química e Bioquímica, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Manuel Prieto
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Fábio Fernandes
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
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8
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Jensen JB, Falkenburger BH, Dickson EJ, de la Cruz L, Dai G, Myeong J, Jung SR, Kruse M, Vivas O, Suh BC, Hille B. Biophysical physiology of phosphoinositide rapid dynamics and regulation in living cells. J Gen Physiol 2022; 154:e202113074. [PMID: 35583815 PMCID: PMC9121023 DOI: 10.1085/jgp.202113074] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 04/28/2022] [Indexed: 01/07/2023] Open
Abstract
Phosphoinositide membrane lipids are ubiquitous low-abundance signaling molecules. They direct many physiological processes that involve ion channels, membrane identification, fusion of membrane vesicles, and vesicular endocytosis. Pools of these lipids are continually broken down and refilled in living cells, and the rates of some of these reactions are strongly accelerated by physiological stimuli. Recent biophysical experiments described here measure and model the kinetics and regulation of these lipid signals in intact cells. Rapid on-line monitoring of phosphoinositide metabolism is made possible by optical tools and electrophysiology. The experiments reviewed here reveal that as for other cellular second messengers, the dynamic turnover and lifetimes of membrane phosphoinositides are measured in seconds, controlling and timing rapid physiological responses, and the signaling is under strong metabolic regulation. The underlying mechanisms of this metabolic regulation remain questions for the future.
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Affiliation(s)
- Jill B. Jensen
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | | | - Eamonn J. Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA
| | - Lizbeth de la Cruz
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Gucan Dai
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | - Jongyun Myeong
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, MO
| | | | - Martin Kruse
- Department of Biology and Program in Neuroscience, Bates College, Lewiston, ME
| | - Oscar Vivas
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Byung-Chang Suh
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
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9
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Sarmento MJ, Borges-Araújo L, Pinto SN, Bernardes N, Ricardo JC, Coutinho A, Prieto M, Fernandes F. Quantitative FRET Microscopy Reveals a Crucial Role of Cytoskeleton in Promoting PI(4,5)P 2 Confinement. Int J Mol Sci 2021; 22:11727. [PMID: 34769158 PMCID: PMC8583820 DOI: 10.3390/ijms222111727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/24/2021] [Accepted: 10/26/2021] [Indexed: 01/30/2023] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is an essential plasma membrane component involved in several cellular functions, including membrane trafficking and cytoskeleton organization. This function multiplicity is partially achieved through a dynamic spatiotemporal organization of PI(4,5)P2 within the membrane. Here, we use a Förster resonance energy transfer (FRET) approach to quantitatively assess the extent of PI(4,5)P2 confinement within the plasma membrane. This methodology relies on the rigorous evaluation of the dependence of absolute FRET efficiencies between pleckstrin homology domains (PHPLCδ) fused with fluorescent proteins and their average fluorescence intensity at the membrane. PI(4,5)P2 is found to be significantly compartmentalized at the plasma membrane of HeLa cells, and these clusters are not cholesterol-dependent, suggesting that membrane rafts are not involved in the formation of these nanodomains. On the other hand, upon inhibition of actin polymerization, compartmentalization of PI(4,5)P2 is almost entirely eliminated, showing that the cytoskeleton network is the critical component responsible for the formation of nanoscale PI(4,5)P2 domains in HeLa cells.
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Affiliation(s)
- Maria J. Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Luís Borges-Araújo
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Sandra N. Pinto
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Nuno Bernardes
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Joana C. Ricardo
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
| | - Ana Coutinho
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Departamento de Química e Bioquímica, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Manuel Prieto
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Fábio Fernandes
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
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10
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Cellular context shapes cyclic nucleotide signaling in neurons through multiple levels of integration. J Neurosci Methods 2021; 362:109305. [PMID: 34343574 DOI: 10.1016/j.jneumeth.2021.109305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/22/2021] [Accepted: 07/29/2021] [Indexed: 02/06/2023]
Abstract
Intracellular signaling with cyclic nucleotides are ubiquitous signaling pathways, yet the dynamics of these signals profoundly differ in different cell types. Biosensor imaging experiments, by providing direct measurements in intact cellular environment, reveal which receptors are activated by neuromodulators and how the coincidence of different neuromodulators is integrated at various levels in the signaling cascade. Phosphodiesterases appear as one important determinant of cross-talk between different signaling pathways. Finally, analysis of signal dynamics reveal that striatal medium-sized spiny neuron obey a different logic than other brain regions such as cortex, probably in relation with the function of this brain region which efficiently detects transient dopamine.
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11
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Monster JL, Donker L, Vliem MJ, Win Z, Matthews HK, Cheah JS, Yamada S, de Rooij J, Baum B, Gloerich M. An asymmetric junctional mechanoresponse coordinates mitotic rounding with epithelial integrity. J Cell Biol 2021; 220:e202001042. [PMID: 33688935 PMCID: PMC7953256 DOI: 10.1083/jcb.202001042] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 12/23/2020] [Accepted: 02/11/2021] [Indexed: 12/14/2022] Open
Abstract
Epithelia are continuously self-renewed, but how epithelial integrity is maintained during the morphological changes that cells undergo in mitosis is not well understood. Here, we show that as epithelial cells round up when they enter mitosis, they exert tensile forces on neighboring cells. We find that mitotic cell-cell junctions withstand these tensile forces through the mechanosensitive recruitment of the actin-binding protein vinculin to cadherin-based adhesions. Surprisingly, vinculin that is recruited to mitotic junctions originates selectively from the neighbors of mitotic cells, resulting in an asymmetric composition of cadherin junctions. Inhibition of junctional vinculin recruitment in neighbors of mitotic cells results in junctional breakage and weakened epithelial barrier. Conversely, the absence of vinculin from the cadherin complex in mitotic cells is necessary to successfully undergo mitotic rounding. Our data thus identify an asymmetric mechanoresponse at cadherin adhesions during mitosis, which is essential to maintain epithelial integrity while at the same time enable the shape changes of mitotic cells.
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Affiliation(s)
- Jooske L. Monster
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Lisa Donker
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marjolein J. Vliem
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Zaw Win
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Helen K. Matthews
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Joleen S. Cheah
- Department of Biomedical Engineering, University of California, Davis, Davis, CA
| | - Soichiro Yamada
- Department of Biomedical Engineering, University of California, Davis, Davis, CA
| | - Johan de Rooij
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Buzz Baum
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Martijn Gloerich
- Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
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12
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Hu Y, Li Q, Kurahara LH, Shioi N, Hiraishi K, Fujita T, Zhu X, Inoue R. An Arrhythmic Mutation E7K Facilitates TRPM4 Channel Activation via Enhanced PIP 2 Interaction. Cells 2021; 10:983. [PMID: 33922380 PMCID: PMC8146980 DOI: 10.3390/cells10050983] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/16/2021] [Accepted: 04/21/2021] [Indexed: 11/17/2022] Open
Abstract
A Ca2+-activated monovalent cation-selective TRPM4 channel is abundantly expressed in the heart. Recently, a single gain-of-function mutation identified in the distal N-terminus of the human TRPM4 channel (Glu5 to Lys5; E7K) was found to be arrhythmogenic because of enhanced cell membrane expression. In this study, we conducted detailed analyses of this mutant channel from more functional aspects, in comparison with its wild type (WT). In an expression system, intracellular application of a short soluble PIP2 (diC8PIP2) restored the single-channel activities of both WT and E7K, which had quickly faded after membrane excision. The potency (Kd) of diC8PIP2 for this recovery was stronger in E7K than its WT (1.44 vs. 2.40 μM). FRET-based PIP2 measurements combined with the Danio rerio voltage-sensing phosphatase (DrVSP) and patch clamping revealed that lowering the endogenous PIP2 level by DrVSP activation reduced the TRPM4 channel activity. This effect was less prominent in E7K than its WT (apparent Kd values estimated from DrVSP-mediated PIP2 depletion: 0.97 and 1.06 μM, respectively), being associated with the differential PIP2-mediated modulation of voltage dependence. Moreover, intracellular perfusion of short N-terminal polypeptides containing either the 'WT' or 'E7K' sequences respectively attenuated the TRPM4 channel activation at whole-cell and single-channel levels, but in both configurations, the E7K polypeptide exerted greater inhibitory effects. These results collectively suggest that N-terminal interaction with endogenous PIP2 is essential for the TRPM4 channel to function, the extent of which may be abnormally strengthened by the E7K mutation through modulating voltage-dependent activation. The altered PIP2 interaction may account for the arrhythmogenic potential of this mutation.
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Affiliation(s)
- Yaopeng Hu
- Department of Physiology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan;
| | - Qin Li
- Biomedical Information Engineering Lab, The University of Aizu, Aizu-Wakamatsu 965-8580, Japan; (Q.L.); (X.Z.)
| | - Lin-Hai Kurahara
- Department of Cardiovascular Physiology, Faculty of Medicine, Kagawa University, Kagawa 761-0793, Japan; (L.-H.K.); (K.H.)
| | - Narumi Shioi
- Department of Chemistry, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan;
| | - Keizo Hiraishi
- Department of Cardiovascular Physiology, Faculty of Medicine, Kagawa University, Kagawa 761-0793, Japan; (L.-H.K.); (K.H.)
| | - Takayuki Fujita
- Department of Physiology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan;
| | - Xin Zhu
- Biomedical Information Engineering Lab, The University of Aizu, Aizu-Wakamatsu 965-8580, Japan; (Q.L.); (X.Z.)
| | - Ryuji Inoue
- Department of Physiology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan;
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13
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Kruse M, Whitten RJ. Control of Neuronal Excitability by Cell Surface Receptor Density and Phosphoinositide Metabolism. Front Pharmacol 2021; 12:663840. [PMID: 33967808 PMCID: PMC8097148 DOI: 10.3389/fphar.2021.663840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 03/29/2021] [Indexed: 12/27/2022] Open
Abstract
Phosphoinositides are members of a family of minor phospholipids that make up about 1% of all lipids in most cell types. Despite their low abundance they have been found to be essential regulators of neuronal activities such as action potential firing, release and re-uptake of neurotransmitters, and interaction of cytoskeletal proteins with the plasma membrane. Activation of several different neurotransmitter receptors can deplete phosphoinositide levels by more than 90% in seconds, thereby profoundly altering neuronal behavior; however, despite the physiological importance of this mechanism we still lack a profound quantitative understanding of the connection between phosphoinositide metabolism and neuronal activity. Here, we present a model that describes phosphoinositide metabolism and phosphoinositide-dependent action potential firing in sympathetic neurons. The model allows for a simulation of activation of muscarinic acetylcholine receptors and its effects on phosphoinositide levels and their regulation of action potential firing in these neurons. In this paper, we describe the characteristics of the model, its calibration to experimental data, and use the model to analyze how alterations of surface density of muscarinic acetylcholine receptors or altered activity levels of a key enzyme of phosphoinositide metabolism influence action potential firing of sympathetic neurons. In conclusion, the model provides a comprehensive framework describing the connection between muscarinic acetylcholine signaling, phosphoinositide metabolism, and action potential firing in sympathetic neurons which can be used to study the role of these signaling systems in health and disease.
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Affiliation(s)
- Martin Kruse
- Department of Biology, Bates College, Lewiston, ME, United States
- Program in Neuroscience, Bates College, Lewiston, ME, United States
| | - Rayne J. Whitten
- Program in Neuroscience, Bates College, Lewiston, ME, United States
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14
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Abstract
Ion channel are embedded in the lipid bilayers of biological membranes. Membrane phospholipids constitute a barrier to ion movement, and they have been considered for a long time as a passive environment for channel proteins. Membrane phospholipids, however, do not only serve as a passive amphipathic environment, but they also modulate channel activity by direct specific lipid-protein interactions. Phosphoinositides are quantitatively minor components of biological membranes, and they play roles in many cellular functions, including membrane traffic, cellular signaling and cytoskeletal organization. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is mainly found in the inner leaflet of the plasma membrane. Its role as a potential ion channel regulator was first appreciated over two decades ago and by now this lipid is a well-established cofactor or regulator of many different ion channels. The past two decades witnessed the steady development of techniques to study ion channel regulation by phosphoinositides with progress culminating in recent cryoEM structures that allowed visualization of how PI(4,5)P2 opens some ion channels. This chapter will provide an overview of the methods to study regulation by phosphoinositides, focusing on plasma membrane ion channels and PI(4,5)P2.
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15
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Margarido AS, Bornes L, Vennin C, van Rheenen J. Cellular Plasticity during Metastasis: New Insights Provided by Intravital Microscopy. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a037267. [PMID: 31615867 DOI: 10.1101/cshperspect.a037267] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Metastasis is a highly dynamic process during which cancer and microenvironmental cells undergo a cascade of events required for efficient dissemination throughout the body. During the metastatic cascade, tumor cells can change their state and behavior, a phenomenon commonly defined as cellular plasticity. To monitor cellular plasticity during metastasis, high-resolution intravital microscopy (IVM) techniques have been developed and allow us to visualize individual cells by repeated imaging in animal models. In this review, we summarize the latest technological advancements in the field of IVM and how they have been applied to monitor metastatic events. In particular, we highlight how longitudinal imaging in native tissues can provide new insights into the plastic physiological and developmental processes that are hijacked by cancer cells during metastasis.
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Affiliation(s)
- Andreia S Margarido
- Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands
| | - Laura Bornes
- Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands
| | - Claire Vennin
- Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands
| | - Jacco van Rheenen
- Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands
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16
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Hertel F, Li S, Chen M, Pott L, Mehta S, Zhang J. Fluorescent Biosensors for Multiplexed Imaging of Phosphoinositide Dynamics. ACS Chem Biol 2020; 15:33-38. [PMID: 31855412 DOI: 10.1021/acschembio.9b00691] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Phosphoinositides constitute a critical family of lipids that regulate numerous cellular processes. Phosphatidylinositol 4,5-bisphosphate (PIP2) is arguably the most important plasma membrane phosphoinositide and is involved in regulating diverse processes. It is also the precursor of phosphatidylinositol 3,4,5-trisphosphate (PIP3), which is critical for growth factor signaling, as well as membrane polarization and dynamics. Studying these lipids remains challenging, because of their compartmentalized activities and location-dependent signaling profiles. Here, we introduce several new genetically encoded fluorescent biosensors, including FRET-based and dimerization-dependent fluorescent protein (ddFP)-based biosensors, that enable real-time monitoring of PIP2 levels in live cells. In addition, we developed a red fluorescent biosensor for 3-phosphoinositides that can be co-imaged with the green PIP2 indicator. Simultaneous visualization of the dynamics of PIP2 and 3-phosphoinositides in the same cell shows that plasma membrane PIP3 formation upon EGF stimulation is coupled to a decrease in the local pool of PIP2.
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Affiliation(s)
| | | | | | - Lutz Pott
- Institute of Physiology, Ruhr-University Bochum, 44801 Bochum, Germany
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17
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Sarco-Endoplasmic Reticulum Calcium Release Model Based on Changes in the Luminal Calcium Content. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:337-370. [DOI: 10.1007/978-3-030-12457-1_14] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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18
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G αq Sensitizes TRPM8 to Inhibition by PI(4,5)P 2 Depletion upon Receptor Activation. J Neurosci 2019; 39:6067-6080. [PMID: 31127000 DOI: 10.1523/jneurosci.2304-18.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 02/07/2023] Open
Abstract
The cold- and menthol-sensitive transient receptor potential melastatin 8 (TRPM8) channel is important for both physiological temperature detection and cold allodynia. Activation of G-protein-coupled receptors (GPCRs) by proinflammatory mediators inhibits these channels. It was proposed that this inhibition proceeds via direct binding of G αq to the channel. TRPM8 requires the plasma membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2 or PIP2] for activity. However, it was claimed that a decrease in cellular levels of this lipid upon receptor activation does not contribute to channel inhibition. Here, we show that supplementing the whole-cell patch pipette with PI(4,5)P2 reduced inhibition of TRPM8 by activation of Gαq-coupled receptors in mouse dorsal root ganglion (DRG) neurons isolated from both sexes. Stimulating the same receptors activated phospholipase C (PLC) and decreased plasma membrane PI(4,5)P2 levels in these neurons. PI(4,5)P2 also reduced inhibition of TRPM8 by activation of heterologously expressed muscarinic M1 receptors. Coexpression of a constitutively active G αq protein that does not couple to PLC inhibited TRPM8 activity, and in cells expressing this protein, decreasing PI(4,5)P2 levels using a voltage-sensitive 5'-phosphatase induced a stronger inhibition of TRPM8 activity than in control cells. Our data indicate that, upon GPCR activation, G αq binding reduces the apparent affinity of TRPM8 for PI(4,5)P2 and thus sensitizes the channel to inhibition induced by decreasing PI(4,5)P2 levels.SIGNIFICANCE STATEMENT Increased sensitivity to heat in inflammation is partially mediated by inhibition of the cold- and menthol-sensitive transient receptor potential melastatin 8 (TRPM8) ion channels. Most inflammatory mediators act via G-protein-coupled receptors that activate the phospholipase C pathway, leading to the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. How receptor activation by inflammatory mediators leads to TRPM8 inhibition is not well understood. Here, we propose that direct binding of G αq both reduces TRPM8 activity and sensitizes the channel to inhibition by decreased levels of its cofactor, PI(4,5)P2 Our data demonstrate the convergence of two downstream effectors of receptor activation, G αq and PI(4,5)P2 hydrolysis, in the regulation of TRPM8.
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19
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Optical approaches for single-cell and subcellular analysis of GPCR-G protein signaling. Anal Bioanal Chem 2019; 411:4481-4508. [PMID: 30927013 DOI: 10.1007/s00216-019-01774-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 03/05/2019] [Accepted: 03/08/2019] [Indexed: 01/05/2023]
Abstract
G protein-coupled receptors (GPCRs), G proteins, and their signaling associates are major signal transducers that control the majority of cellular signaling and regulate key biological functions including immune, neurological, cardiovascular, and metabolic processes. These pathways are targeted by over one-third of drugs on the market; however, the current understanding of their function is limited and primarily derived from cell-destructive approaches providing an ensemble of static, multi-cell information about the status and composition of molecules. Spatiotemporal behavior of molecules involved is crucial to understanding in vivo cell behaviors both in health and disease, and the advent of genetically encoded fluorescence proteins and small fluorophore-based biosensors has facilitated the mapping of dynamic signaling in cells with subcellular acuity. Since we and others have developed optogenetic methods to regulate GPCR-G protein signaling in single cells and subcellular regions using dedicated wavelengths, the desire to develop and adopt optogenetically amenable assays to measure signaling has motivated us to take a broader look at the available optical tools and approaches compatible with measuring single-cell and subcellular GPCR-G protein signaling. Here we review such key optical approaches enabling the examination of GPCR, G protein, secondary messenger, and downstream molecules such as kinase and lipid signaling in living cells. The methods reviewed employ both fluorescence and bioluminescence detection. We not only further elaborate the underlying principles of these sensors but also discuss the experimental criteria and limitations to be considered during their use in single-cell and subcellular signal mapping.
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20
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Kienitz MC, Niemeyer A, König GM, Kostenis E, Pott L, Rinne A. Biased signaling of Ca 2+-sensing receptors in cardiac myocytes regulates GIRK channel activity. J Mol Cell Cardiol 2019; 130:107-121. [PMID: 30935998 DOI: 10.1016/j.yjmcc.2019.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 03/06/2019] [Accepted: 03/27/2019] [Indexed: 12/22/2022]
Abstract
Ca2+-sensing receptors (CaSRs) belong to the class C of G protein-coupled receptors and are activated by extracellular Ca2+. CaSRs display biased G protein signaling by coupling to different classes of heterotrimeric G proteins depending on agonist and cell type. In this study we used fluorescent biosensors to directly analyze G protein coupling to CaSRs and downstream signaling in living cells. In HEK 293 cells, CaSRs displayed biased signaling: elevation of extracellular Ca2+ or application of the alternative agonist spermine caused activation of Gi- and Gq-proteins. Adult cardiac myocytes express endogenous CaSRs, which have been implicated in regulating Ca2+ signaling and contractility. Biased signaling of CaSRs has not been investigated in these cells. To evaluate efficiencies of Gi- and Gq-signaling via CaSRs in rat atrial myocytes, we measured G protein-activated K+ (GIRK) channels. Activation of GIRK requires binding of Gβγ subunits released from Gi proteins, whereas Gq-signaling results in inhibition of GIRK channel activity. Stimulation of CaSRs by Ca2+ or spermine failed to directly activate Gi and GIRK channels. When GIRK channels were pre-activated via endogenous M2 receptors, stimulation of CaSRs caused pronounced inhibition of GIRK currents. This effect was specific to CaSR activation: GIRK current inhibition was sensitive to NPS-2143, a negative allosteric modulator of CaSRs, and abrogated by FR900359, a direct inhibitor of Gq. GIRK current inhibition was also sensitive to the PKC inhibitor chelerythrine, suggesting that following activation of CaSR and Gq, GIRK currents are modulated by PKC phosphorylation. We conclude from this data that cardiac CaSRs do not activate Gi and affect GIRK currents preferentially via the Gq/PKC pathway.
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Affiliation(s)
| | - Anne Niemeyer
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Gabriele M König
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Evi Kostenis
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Lutz Pott
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Andreas Rinne
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
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21
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Tóth JT, Gulyás G, Hunyady L, Várnai P. Development of Nonspecific BRET-Based Biosensors to Monitor Plasma Membrane Inositol Lipids in Living Cells. Methods Mol Biol 2019; 1949:23-34. [PMID: 30790246 DOI: 10.1007/978-1-4939-9136-5_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
There are several difficulties to face when investigating the role of phosphoinositides. Although they are present in most organelles, their concentration is very low, sometimes undetectable with the available methods; moreover, their level can quickly change upon several external stimuli. Here we introduce a newly improved lipid sensor tool-set based on the balanced expression of luciferase-fused phosphoinositide recognizing protein domains and a Venus protein targeted to the plasma membrane, allowing us to perform Bioluminescence Resonance Energy Transfer (BRET) measurements that reflect phosphoinositide changes in a population of transiently transfected cells. This method is highly sensitive, specific, and capable of semiquantitative characterization of plasma membrane phosphoinositide changes with high temporal resolution.
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Affiliation(s)
- József T Tóth
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary.,Faculty of Medicine, Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - Gergő Gulyás
- Faculty of Medicine, Department of Physiology Semmelweis University, Budapest, Hungary
| | - László Hunyady
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary.,MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Péter Várnai
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary. .,MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary.
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22
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Greenwald EC, Mehta S, Zhang J. Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks. Chem Rev 2018; 118:11707-11794. [PMID: 30550275 PMCID: PMC7462118 DOI: 10.1021/acs.chemrev.8b00333] [Citation(s) in RCA: 316] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.
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Affiliation(s)
- Eric C Greenwald
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Sohum Mehta
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Jin Zhang
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
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23
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Argenzio E, Klarenbeek J, Kedziora KM, Nahidiazar L, Isogai T, Perrakis A, Jalink K, Moolenaar WH, Innocenti M. Profilin binding couples chloride intracellular channel protein CLIC4 to RhoA-mDia2 signaling and filopodium formation. J Biol Chem 2018; 293:19161-19176. [PMID: 30381396 PMCID: PMC6302171 DOI: 10.1074/jbc.ra118.002779] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 10/26/2018] [Indexed: 12/31/2022] Open
Abstract
Chloride intracellular channel 4 (CLIC4) is a cytosolic protein implicated in diverse actin-based processes, including integrin trafficking, cell adhesion, and tubulogenesis. CLIC4 is rapidly recruited to the plasma membrane by RhoA-activating agonists and then partly colocalizes with β1 integrins. Agonist-induced CLIC4 translocation depends on actin polymerization and requires conserved residues that make up a putative binding groove. However, the mechanism and significance of CLIC4 trafficking have been elusive. Here, we show that RhoA activation by either lysophosphatidic acid (LPA) or epidermal growth factor is necessary and sufficient for CLIC4 translocation to the plasma membrane and involves regulation by the RhoA effector mDia2, a driver of actin polymerization and filopodium formation. We found that CLIC4 binds the G-actin–binding protein profilin-1 via the same residues that are required for CLIC4 trafficking. Consistently, shRNA-induced profilin-1 silencing impaired agonist-induced CLIC4 trafficking and the formation of mDia2-dependent filopodia. Conversely, CLIC4 knockdown increased filopodium formation in an integrin-dependent manner, a phenotype rescued by wild-type CLIC4 but not by the trafficking-incompetent mutant CLIC4(C35A). Furthermore, CLIC4 accelerated LPA-induced filopodium retraction. We conclude that through profilin-1 binding, CLIC4 functions in a RhoA–mDia2–regulated signaling network to integrate cortical actin assembly and membrane protrusion. We propose that agonist-induced CLIC4 translocation provides a feedback mechanism that counteracts formin-driven filopodium formation.
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Affiliation(s)
| | | | | | | | | | - Anastassis Perrakis
- Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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24
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Tateyama M, Kubo Y. Gi/o-coupled muscarinic receptors co-localize with GIRK channel for efficient channel activation. PLoS One 2018; 13:e0204447. [PMID: 30240440 PMCID: PMC6150519 DOI: 10.1371/journal.pone.0204447] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 09/07/2018] [Indexed: 01/09/2023] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channel regulates cellular excitability upon activation of Gi/o-coupled receptors. In Gi/o-coupled muscarinic M2R, the intracellular third loop (i3) is known as a key domain for Gi/o coupling, because replacement of i3 of Gq-coupled muscarinic M1R with that of M2R enables the chimeric receptor (MC9) to activate the GIRK channel. In the present study, we showed that MC9, but not M1R, co-localizes with the GIRK channel and Gαi1 by Förster resonance energy transfer (FRET) analysis. When M1R was forced to stay adjacent to the channel through ligation with short linkers, M1R activated the GIRK channel. FRET analysis further suggested that the efficacy of channel activation is correlated with the linker length between M1R and the GIRK channel. The results show that co-localization is an important factor for activating the GIRK channel. In contrast, for MC9 and M2R, the GIRK channel was activated even when they were connected by long linkers, suggesting the formation of a molecular complex even in the absence of a linker. We also observed that replacement of 13 amino acid residues at the N-terminal end of i3 of MC9 with those of M1R impaired the co-localization with the GIRK channel as well as channel activation. These results show that localization of the receptor near the GIRK channel is a key factor in efficiently activating the channel and that the N-terminal end of i3 of M2R plays an important role in co-localization.
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Affiliation(s)
- Michihiro Tateyama
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan
- * E-mail:
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan
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25
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Leitner MG, Thallmair V, Wilke BU, Neubert V, Kronimus Y, Halaszovich CR, Oliver D. The N-terminal homology (ENTH) domain of Epsin 1 is a sensitive reporter of physiological PI(4,5)P 2 dynamics. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:433-442. [PMID: 30670192 DOI: 10.1016/j.bbalip.2018.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/18/2018] [Accepted: 08/04/2018] [Indexed: 11/15/2022]
Abstract
Phospholipase Cβ (PLCβ)-induced depletion of phosphatidylinositol-(4,5)-bisphosphate (PI(4,5)P2) transduces a plethora of signals into cellular responses. Importance and diversity of PI(4,5)P2-dependent processes led to strong need for biosensors of physiological PI(4,5)P2 dynamics applicable in live-cell experiments. Membrane PI(4,5)P2 can be monitored with fluorescently-labelled phosphoinositide (PI) binding domains that associate to the membrane depending on PI(4,5)P2 levels. The pleckstrin homology domain of PLCδ1 (PLCδ1-PH) and the C-terminus of tubby protein (tubbyCT) are two such sensors widely used to study PI(4,5)P2 signaling. However, certain limitations apply to both: PLCδ1-PH binds cytoplasmic inositol-1,4,5-trisphosphate (IP3) produced from PI(4,5)P2 through PLCβ, and tubbyCT responses do not faithfully report on PLCβ-dependent PI(4,5)P2 dynamics. In searching for an improved biosensor, we fused N-terminal homology domain of Epsin1 (ENTH) to GFP and examined use of this construct as genetically-encoded biosensor for PI(4,5)P2 dynamics in living cells. We utilized recombinant tools to manipulate PI or Gq protein-coupled receptors (GqPCR) to stimulate PLCβ signaling and characterized PI binding properties of ENTH-GFP with total internal reflection (TIRF) and confocal microscopy. ENTH-GFP specifically recognized membrane PI(4,5)P2 without interacting with IP3, as demonstrated by dialysis of cells with the messenger through a patch pipette. Utilizing Ci-VSP to titrate PI(4,5)P2 levels, we found that ENTH-GFP had low PI(4,5)P2 affinity. Accordingly, ENTH-GFP was highly sensitive to PLCβ-dependent PI(4,5)P2 depletion, and in contrast to PLCδ1-PH, overexpression of ENTH-GFP did not attenuate GqPCR signaling. Taken together, ENTH-GFP detects minute changes of PI(4,5)P2 levels and provides an important complementation of experimentally useful reporters of PI(4,5)P2 dynamics in physiological pathways.
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Affiliation(s)
- Michael G Leitner
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria; Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany.
| | - Veronika Thallmair
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Bettina U Wilke
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Valentin Neubert
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Yannick Kronimus
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Christian R Halaszovich
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany; DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-University, Germany; Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
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26
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Measurement of intracellular concentration of fluorescently-labeled targets in living cells. PLoS One 2018; 13:e0194031. [PMID: 29694385 PMCID: PMC5918622 DOI: 10.1371/journal.pone.0194031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 02/16/2018] [Indexed: 02/04/2023] Open
Abstract
Estimations of intracellular concentrations of fluorescently-labeled molecules within living cells are very important for guidance of biological experiments and interpretation of their results. Here we propose a simple and universal approach for such estimations. The approach is based upon common knowledge that the dye fluorescence is directly proportional to its quantum yield and the number of its molecules and that a coefficient of proportionality is determined by spectral properties of the dye and optical equipment used to record fluorescent signals. If two fluorescent dyes are present in the same volume, then a ratio of their concentrations is equal to a ratio of their fluorescence multiplied by some dye- and equipment-dependent coefficient. Thus, if the coefficient and concentration of one dye is known then the concentration of another dye can be determined. Here we have demonstrated how to calculate this coefficient (called a ratio factor) and how to use it for concentration measurements of fluorescently tagged molecules. As an example of how this approach can be used, we estimated a concentration of exogenously expressed neuronal Ca2+ sensor protein, hippocalcin, tagged by a fluorescent protein in a dendritic tree of rat hippocampal neurons loaded via a patch pipette with Alexa Fluor dye of known concentration. The new approach should allow performing a fast, inexpensive and reliable quantitative analysis of fluorescently-labeled targets in different parts of living cells.
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27
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Huang W, Wang X, Endo-Streeter S, Barrett M, Waybright J, Wohlfeld C, Hajicek N, Harden TK, Sondek J, Zhang Q. A membrane-associated, fluorogenic reporter for mammalian phospholipase C isozymes. J Biol Chem 2017; 293:1728-1735. [PMID: 29263090 DOI: 10.1074/jbc.ra117.000926] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 12/05/2017] [Indexed: 11/06/2022] Open
Abstract
A diverse group of cell-surface receptors, including many G protein-coupled receptors and receptor tyrosine kinases, activate phospholipase C (PLC) isozymes to hydrolyze phosphatidylinositol 4,5-bisphosphate into the second messengers diacylglycerol and 1,4,5-inositol trisphosphate. Consequently, PLCs control various cellular processes, and their aberrant regulation contributes to many diseases, including cancer, atherosclerosis, and rheumatoid arthritis. Despite the widespread importance of PLCs in human biology and disease, it has been impossible to directly monitor the real-time activation of these enzymes at membranes. To overcome this limitation, here we describe XY-69, a fluorogenic reporter that preferentially partitions into membranes and provides a selective tool for measuring the real-time activity of PLCs as either purified enzymes or in cellular lysates. Indeed, XY-69 faithfully reported the membrane-dependent activation of PLC-β3 by Gαq Therefore, XY-69 can replace radioactive phosphatidylinositol 4,5-bisphosphate used in conventional PLC assays and will enable high-throughput screens to identify both orthosteric and allosteric PLC inhibitors. In the future, cell-permeable variants of XY-69 represent promising candidates for reporting the activation of PLCs in live cells with high spatiotemporal resolution.
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Affiliation(s)
- Weigang Huang
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | - Xiaoyang Wang
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | | | | | - Jarod Waybright
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | - Christian Wohlfeld
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy
| | | | | | - John Sondek
- Departments of Pharmacology and.,Biochemistry and Biophysics, School of Medicine, and.,the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Qisheng Zhang
- From the Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, .,Departments of Pharmacology and.,the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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28
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Traynor-Kaplan A, Kruse M, Dickson EJ, Dai G, Vivas O, Yu H, Whittington D, Hille B. Fatty-acyl chain profiles of cellular phosphoinositides. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:513-522. [PMID: 28189644 PMCID: PMC5392126 DOI: 10.1016/j.bbalip.2017.02.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 01/31/2017] [Accepted: 02/07/2017] [Indexed: 12/24/2022]
Abstract
Phosphoinositides are rapidly turning-over phospholipids that play key roles in intracellular signaling and modulation of membrane effectors. Through technical refinements we have improved sensitivity in the analysis of the phosphoinositide PI, PIP, and PIP2 pools from living cells using mass spectrometry. This has permitted further resolution in phosphoinositide lipidomics from cell cultures and small samples of tissue. The technique includes butanol extraction, derivatization of the lipids, post-column infusion of sodium to stabilize formation of sodiated adducts, and electrospray ionization mass spectrometry in multiple reaction monitoring mode, achieving a detection limit of 20pg. We describe the spectrum of fatty-acyl chains in the cellular phosphoinositides. Consistent with previous work in other mammalian primary cells, the 38:4 fatty-acyl chains dominate in the phosphoinositides of the pineal gland and of superior cervical ganglia, and many additional fatty acid combinations are found at low abundance. However, Chinese hamster ovary cells and human embryonic kidney cells (tsA201) in culture have different fatty-acyl chain profiles that change with growth state. Their 38:4 lipids lose their dominance as cultures approach confluence. The method has good time resolution and follows well the depletion in <20s of both PIP2 and PIP that results from strong activation of Gq-coupled receptors. The receptor-activated phospholipase C exhibits no substrate selectivity among the various fatty-acyl chain combinations.
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Affiliation(s)
- Alexis Traynor-Kaplan
- ATK Innovation, Analytics and Discovery, North Bend, WA 98045, USA; Department of Medicine/Gastroenterology, University of Washington School of Medicine, Seattle, WA, USA.
| | - Martin Kruse
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, USA
| | - Eamonn J Dickson
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, USA
| | - Gucan Dai
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, USA
| | - Oscar Vivas
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, USA
| | - Haijie Yu
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, USA
| | - Dale Whittington
- Department of Medicinal Chemistry, University of Washington School of Medicine, Seattle, WA, USA
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, USA
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29
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Bindels DS, Haarbosch L, van Weeren L, Postma M, Wiese KE, Mastop M, Aumonier S, Gotthard G, Royant A, Hink MA, Gadella TWJ. mScarlet: a bright monomeric red fluorescent protein for cellular imaging. Nat Methods 2017; 14:53-56. [PMID: 27869816 DOI: 10.1038/nmeth.4074] [Citation(s) in RCA: 642] [Impact Index Per Article: 91.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 10/20/2016] [Indexed: 12/24/2022]
Abstract
We report the engineering of mScarlet, a truly monomeric red fluorescent protein with record brightness, quantum yield (70%) and fluorescence lifetime (3.9 ns). We developed mScarlet starting with a consensus synthetic template and using improved spectroscopic screening techniques; mScarlet's crystal structure reveals a planar and rigidified chromophore. mScarlet outperforms existing red fluorescent proteins as a fusion tag, and it is especially useful as a Förster resonance energy transfer (FRET) acceptor in ratiometric imaging.
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Affiliation(s)
- Daphne S Bindels
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Lindsay Haarbosch
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Laura van Weeren
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Marten Postma
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Katrin E Wiese
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Marieke Mastop
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Sylvain Aumonier
- European Synchrotron Radiation Facility, Grenoble, France
- Institut de Biologie Structurale, Université Grenoble Alpes, CNRS, CEA, Grenoble, F-38044, France
| | - Guillaume Gotthard
- European Synchrotron Radiation Facility, Grenoble, France
- Institut de Biologie Structurale, Université Grenoble Alpes, CNRS, CEA, Grenoble, F-38044, France
| | - Antoine Royant
- European Synchrotron Radiation Facility, Grenoble, France
- Institut de Biologie Structurale, Université Grenoble Alpes, CNRS, CEA, Grenoble, F-38044, France
| | - Mark A Hink
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
| | - Theodorus W J Gadella
- Section of Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
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30
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Várnai P, Gulyás G, Tóth DJ, Sohn M, Sengupta N, Balla T. Quantifying lipid changes in various membrane compartments using lipid binding protein domains. Cell Calcium 2016; 64:72-82. [PMID: 28088320 DOI: 10.1016/j.ceca.2016.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/28/2016] [Accepted: 12/29/2016] [Indexed: 11/30/2022]
Abstract
One of the largest challenges in cell biology is to map the lipid composition of the membranes of various organelles and define the exact location of processes that control the synthesis and distribution of lipids between cellular compartments. The critical role of phosphoinositides, low-abundant lipids with rapid metabolism and exceptional regulatory importance in the control of almost all aspects of cellular functions created the need for tools to visualize their localizations and dynamics at the single cell level. However, there is also an increasing need for methods to determine the cellular distribution of other lipids regulatory or structural, such as diacylglycerol, phosphatidic acid, or other phospholipids and cholesterol. This review will summarize recent advances in this research field focusing on the means by which changes can be described in more quantitative terms.
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Affiliation(s)
- Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gergő Gulyás
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Dániel J Tóth
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States; Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Mira Sohn
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States
| | - Nivedita Sengupta
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States.
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31
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Jung SR, Seo JB, Deng Y, Asbury CL, Hille B, Koh DS. Contributions of protein kinases and β-arrestin to termination of protease-activated receptor 2 signaling. ACTA ACUST UNITED AC 2016; 147:255-71. [PMID: 26927499 PMCID: PMC4772372 DOI: 10.1085/jgp.201511477] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Systematic imaging studies and modeling reveal new details of the regulation of the Gq-coupled GPCR, protease-activated receptor 2, by phosphorylation and β-arrestin. Activated Gq protein–coupled receptors (GqPCRs) can be desensitized by phosphorylation and β-arrestin binding. The kinetics and individual contributions of these two mechanisms to receptor desensitization have not been fully distinguished. Here, we describe the shut off of protease-activated receptor 2 (PAR2). PAR2 activates Gq and phospholipase C (PLC) to hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP2) into diacylglycerol and inositol trisphosphate (IP3). We used fluorescent protein–tagged optical probes to monitor several consequences of PAR2 signaling, including PIP2 depletion and β-arrestin translocation in real time. During continuous activation of PAR2, PIP2 was depleted transiently and then restored within a few minutes, indicating fast receptor activation followed by desensitization. Knockdown of β-arrestin 1 and 2 using siRNA diminished the desensitization, slowing PIP2 restoration significantly and even adding a delayed secondary phase of further PIP2 depletion. These effects of β-arrestin knockdown on PIP2 recovery were prevented when serine/threonine phosphatases that dephosphorylate GPCRs were inhibited. Thus, PAR2 may continuously regain its activity via dephosphorylation when there is insufficient β-arrestin to trap phosphorylated receptors. Similarly, blockers of protein kinase C (PKC) and G protein–coupled receptor kinase potentiated the PIP2 depletion. In contrast, an activator of PKC inhibited receptor activation, presumably by augmenting phosphorylation of PAR2. Our interpretations were strengthened by modeling. Simulations supported the conclusions that phosphorylation of PAR2 by protein kinases initiates receptor desensitization and that recruited β-arrestin traps the phosphorylated state of the receptor, protecting it from phosphatases. Speculative thinking suggested a sequestration of phosphatidylinositol 4-phosphate 5 kinase (PIP5K) to the plasma membrane by β-arrestin to explain why knockdown of β-arrestin led to secondary depletion of PIP2. Indeed, artificial recruitment of PIP5K removed the secondary loss of PIP2 completely. Altogether, our experimental and theoretical approaches demonstrate roles and dynamics of the protein kinases, β-arrestin, and PIP5K in the desensitization of PAR2.
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Affiliation(s)
- Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Jong Bae Seo
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Yi Deng
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Duk-Su Koh
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195 Department of Physics, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, Republic of Korea
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32
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Abstract
Phosphatases play key roles in normal physiology and diseases. Studying phosphatases has been both essential and challenging, and the application of conventional genetic and biochemical methods has led to crucial but still limited understanding of their mechanisms, substrates, and exclusive functions within highly intricate networks. With the advances in technologies such as cellular imaging and molecular and chemical biology in terms of sensitive tools and methods, the phosphatase field has thrived in the past years and has set new insights for cell signaling studies and for therapeutic development. In this review, we give an overview of the existing interdisciplinary tools for phosphatases, give examples on how they have been applied to increase our understanding of these enzymes, and suggest how they-and other tools yet barely used in the phosphatase field-might be adapted to address future questions and challenges.
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Affiliation(s)
- Sara Fahs
- European Molecular Biology Laboratory, Genome Biology
Unit, Meyerhofstrasse
1, 69117 Heidelberg, Germany
| | - Pablo Lujan
- European Molecular Biology Laboratory, Genome Biology
Unit, Meyerhofstrasse
1, 69117 Heidelberg, Germany
| | - Maja Köhn
- European Molecular Biology Laboratory, Genome Biology
Unit, Meyerhofstrasse
1, 69117 Heidelberg, Germany
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33
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Miyamoto A, Mikoshiba K. Probes for manipulating and monitoring IP 3. Cell Calcium 2016; 64:57-64. [PMID: 27887748 DOI: 10.1016/j.ceca.2016.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022]
Abstract
Inositol 1,4,5-trisphosphate (IP3) is an important second messenger produced via G-protein-coupled receptor- or receptor tyrosine kinase-mediated pathways. IP3 levels induce Ca2+ release from the endoplasmic reticulum (ER) via IP3 receptor (IP3R) located in the ER membrane. The resultant spatiotemporal pattern of Ca2+ signals regulates diverse cellular functions, including fertilization, gene expression, synaptic plasticity, and cell death. Therefore, monitoring and manipulating IP3 levels is important to elucidate not only the functions of IP3-mediated pathways but also the encoding mechanism of IP3R as a converter of intracellular signals from IP3 to Ca2+.
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Affiliation(s)
- Akitoshi Miyamoto
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Kienitz MC, Vladimirova D, Müller C, Pott L, Rinne A. Receptor Species-dependent Desensitization Controls KCNQ1/KCNE1 K+ Channels as Downstream Effectors of Gq Protein-coupled Receptors. J Biol Chem 2016; 291:26410-26426. [PMID: 27834678 DOI: 10.1074/jbc.m116.746974] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/09/2016] [Indexed: 12/17/2022] Open
Abstract
Activation of Gq protein-coupled receptors (GqPCRs) might induce divergent cellular responses, related to receptor-specific activation of different branches of the Gq signaling pathway. Receptor-specific desensitization provides a mechanism of effector modulation by restricting the spatiotemporal activation of signaling components downstream of Gq We quantified signaling events downstream of GqPCR activation with FRET-based biosensors in CHO and HEK 293 cells. KCNQ1/KCNE1 channels (IKs) were measured as a functional readout of receptor-specific activation. Activation of muscarinic M1 receptors (M1-Rs) caused robust and reversible inhibition of IKs. In contrast, activation of α1B-adrenergic receptors (α1B-ARs) induced transient inhibition of IKs, which turned into delayed facilitation after agonist withdrawal. As a novel finding, we demonstrate that GqPCR-specific kinetics of IKs modulation are determined by receptor-specific desensitization, evident at the level of Gαq activation, phosphatidylinositol 4,5-bisphosphate (PIP2) depletion, and diacylglycerol production. Sustained IKs inhibition during M1-R stimulation is attributed to robust membrane PIP2 depletion, whereas the rapid desensitization of α1B-AR delimits PIP2 reduction and augments current activation by protein kinase C (PKC). Overexpression of Ca2+-independent PKCδ did not affect the time course of α1B-AR-induced diacylglycerol formation, excluding a contribution of PKCδ to α1B-AR desensitization. Pharmacological inhibition of Ca2+-dependent PKC isoforms abolished fast α1B receptor desensitization and augmented IKs reduction, but did not affect IKs facilitation. These data indicate a contribution of Ca2+-dependent PKCs to α1B-AR desensitization, whereas IKs facilitation is induced by Ca2+-independent PKC isoforms. In contrast, neither inhibition of Ca2+-dependent/Ca2+-independent isoforms nor overexpression of PKCδ induced M1 receptor desensitization, excluding a contribution of PKC to M1-R-induced IKs modulation.
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Affiliation(s)
- Marie-Cécile Kienitz
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Dilyana Vladimirova
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Christian Müller
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Lutz Pott
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Andreas Rinne
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
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35
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Bolbat A, Schultz C. Recent developments of genetically encoded optical sensors for cell biology. Biol Cell 2016; 109:1-23. [PMID: 27628952 DOI: 10.1111/boc.201600040] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/06/2016] [Accepted: 09/09/2016] [Indexed: 12/14/2022]
Abstract
Optical sensors are powerful tools for live cell research as they permit to follow the location, concentration changes or activities of key cellular players such as lipids, ions and enzymes. Most of the current sensor probes are based on fluorescence which provides great spatial and temporal precision provided that high-end microscopy is used and that the timescale of the event of interest fits the response time of the sensor. Many of the sensors developed in the past 20 years are genetically encoded. There is a diversity of designs leading to simple or sometimes complicated applications for the use in live cells. Genetically encoded sensors began to emerge after the discovery of fluorescent proteins, engineering of their improved optical properties and the manipulation of their structure through application of circular permutation. In this review, we will describe a variety of genetically encoded biosensor concepts, including those for intensiometric and ratiometric sensors based on single fluorescent proteins, Forster resonance energy transfer-based sensors, sensors utilising bioluminescence, sensors using self-labelling SNAP- and CLIP-tags, and finally tetracysteine-based sensors. We focus on the newer developments and discuss the current approaches and techniques for design and application. This will demonstrate the power of using optical sensors in cell biology and will help opening the field to more systematic applications in the future.
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Affiliation(s)
- Andrey Bolbat
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Heidelberg, 69117, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Heidelberg, 69117, Germany
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36
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Tateyama M, Kubo Y. Stabilizing effects of G protein on the active conformation of adenosine A 1 receptor differ depending on G protein type. Eur J Pharmacol 2016; 788:122-131. [DOI: 10.1016/j.ejphar.2016.06.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 06/15/2016] [Accepted: 06/15/2016] [Indexed: 01/07/2023]
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37
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Abstract
Acidic phospholipids are minor membrane lipids but critically important for signaling events. The main acidic phospholipids are phosphatidylinositol phosphates (PIPs also known as phosphoinositides), phosphatidylserine (PS), and phosphatidic acid (PA). Acidic phospholipids are precursors of second messengers of key signaling cascades or are second messengers themselves. They regulate the localization and activation of many proteins, and are involved in virtually all membrane trafficking events. As such, it is crucial to understand the subcellular localization and dynamics of each of these lipids within the cell. Over the years, several techniques have emerged in either fixed or live cells to analyze the subcellular localization and dynamics of acidic phospholipids. In this chapter, we review one of them: the use of genetically encoded biosensors that are based on the expression of specific lipid binding domains (LBDs) fused to fluorescent proteins. We discuss how to design such sensors, including the criteria for selecting the lipid binding domains of interest and to validate them. We also emphasize the care that must be taken during data analysis as well as the main limitations and advantages of this approach.
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Affiliation(s)
- Matthieu Pierre Platre
- Laboratoire de Reproduction et Développement des Plantes, CNRS, INRA, ENS Lyon, UCBL, Université de Lyon, 46 Allée d'Italie, 69364, Lyon Cedex 07, France
| | - Yvon Jaillais
- Laboratoire de Reproduction et Développement des Plantes, CNRS, INRA, ENS Lyon, UCBL, Université de Lyon, 46 Allée d'Italie, 69364, Lyon Cedex 07, France.
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de la Cruz L, Puente EI, Reyes-Vaca A, Arenas I, Garduño J, Bravo-Martínez J, Garcia DE. PIP2 in pancreatic β-cells regulates voltage-gated calcium channels by a voltage-independent pathway. Am J Physiol Cell Physiol 2016; 311:C630-C640. [PMID: 27488666 DOI: 10.1152/ajpcell.00111.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 07/29/2016] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is a membrane phosphoinositide that regulates the activity of many ion channels. Influx of calcium primarily through voltage-gated calcium (CaV) channels promotes insulin secretion in pancreatic β-cells. However, whether CaV channels are regulated by PIP2, as is the case for some non-insulin-secreting cells, is unknown. The purpose of this study was to investigate whether CaV channels are regulated by PIP2 depletion in pancreatic β-cells through activation of a muscarinic pathway induced by oxotremorine methiodide (Oxo-M). CaV channel currents were recorded by the patch-clamp technique. The CaV current amplitude was reduced by activation of the muscarinic receptor 1 (M1R) in the absence of kinetic changes. The Oxo-M-induced inhibition exhibited the hallmarks of voltage-independent regulation and did not involve PKC activation. A small fraction of the Oxo-M-induced CaV inhibition was diminished by a high concentration of Ca2+ chelator, whereas ≥50% of this inhibition was prevented by diC8-PIP2 dialysis. Localization of PIP2 in the plasma membrane was examined by transfecting INS-1 cells with PH-PLCδ1, which revealed a close temporal association between PIP2 hydrolysis and CaV channel inhibition. Furthermore, the depletion of PIP2 by a voltage-sensitive phosphatase reduced CaV currents in a way similar to that observed following M1R activation. These results indicate that activation of the M1R pathway inhibits the CaV channel via PIP2 depletion by a Ca2+-dependent mechanism in pancreatic β- and INS-1 cells and thereby support the hypothesis that membrane phospholipids regulate ion channel activity by interacting with ion channels.
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Affiliation(s)
- Lizbeth de la Cruz
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Erika I Puente
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Arturo Reyes-Vaca
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Isabel Arenas
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Julieta Garduño
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - Jorge Bravo-Martínez
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
| | - David E Garcia
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico, México
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Phosphoinositide 5- and 3-phosphatase activities of a voltage-sensing phosphatase in living cells show identical voltage dependence. Proc Natl Acad Sci U S A 2016; 113:E3686-95. [PMID: 27222577 DOI: 10.1073/pnas.1606472113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Voltage-sensing phosphatases (VSPs) are homologs of phosphatase and tensin homolog (PTEN), a phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] 3-phosphatase. However, VSPs have a wider range of substrates, cleaving 3-phosphate from PI(3,4)P2 and probably PI(3,4,5)P3 as well as 5-phosphate from phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and PI(3,4,5)P3 in response to membrane depolarization. Recent proposals say these reactions have differing voltage dependence. Using Förster resonance energy transfer probes specific for different PIs in living cells with zebrafish VSP, we quantitate both voltage-dependent 5- and 3-phosphatase subreactions against endogenous substrates. These activities become apparent with different voltage thresholds, voltage sensitivities, and catalytic rates. As an analytical tool, we refine a kinetic model that includes the endogenous pools of phosphoinositides, endogenous phosphatase and kinase reactions connecting them, and four exogenous voltage-dependent 5- and 3-phosphatase subreactions of VSP. We show that apparent voltage threshold differences for seeing effects of the 5- and 3-phosphatase activities in cells are not due to different intrinsic voltage dependence of these reactions. Rather, the reactions have a common voltage dependence, and apparent differences arise only because each VSP subreaction has a different absolute catalytic rate that begins to surpass the respective endogenous enzyme activities at different voltages. For zebrafish VSP, our modeling revealed that 3-phosphatase activity against PI(3,4,5)P3 is 55-fold slower than 5-phosphatase activity against PI(4,5)P2; thus, PI(4,5)P2 generated more slowly from dephosphorylating PI(3,4,5)P3 might never accumulate. When 5-phosphatase activity was counteracted by coexpression of a phosphatidylinositol 4-phosphate 5-kinase, there was accumulation of PI(4,5)P2 in parallel to PI(3,4,5)P3 dephosphorylation, emphasizing that VSPs can cleave the 3-phosphate of PI(3,4,5)P3.
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Rohacs T. Phosphoinositide signaling in somatosensory neurons. Adv Biol Regul 2016; 61:2-16. [PMID: 26724974 PMCID: PMC4884561 DOI: 10.1016/j.jbior.2015.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 11/06/2015] [Accepted: 11/07/2015] [Indexed: 02/03/2023]
Abstract
Somatosensory neurons of the dorsal root ganglia (DRG) and trigeminal ganglia (TG) are responsible for detecting thermal and tactile stimuli. They are also the primary neurons mediating pain and itch. A large number of cell surface receptors in these neurons couple to phospholipase C (PLC) enzymes leading to the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and the generation of downstream signaling molecules. These neurons also express many different ion channels, several of which are regulated by phosphoinositides. This review will summarize the knowledge on phosphoinositide signaling in DRG neurons, with special focus on effects on sensory and other ion channels.
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Affiliation(s)
- Tibor Rohacs
- Rutgers, New Jersey Medical School, Newark, NJ, USA.
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41
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Guigas G, Weiss M. Effects of protein crowding on membrane systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:2441-2450. [PMID: 26724385 DOI: 10.1016/j.bbamem.2015.12.021] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/19/2015] [Accepted: 12/21/2015] [Indexed: 10/22/2022]
Abstract
Cellular membranes are typically decorated with a plethora of embedded and adsorbed macromolecules, e.g. proteins, that participate in numerous vital processes. With typical surface densities of 30,000 proteins per μm(2) cellular membranes are indeed crowded places that leave only few nanometers of private space for individual proteins. Here, we review recent advances in our understanding of protein crowding in membrane systems. We first give a brief overview on state-of-the-art approaches in experiment and simulation that are frequently used to study crowded membranes. After that, we review how crowding can affect diffusive transport of proteins and lipids in membrane systems. Next, we discuss lipid and protein sorting in crowded membrane systems, including effects like protein cluster formation, phase segregation, and lipid droplet formation. Subsequently, we highlight recent progress in uncovering crowding-induced conformational changes of membranes, e.g. membrane budding and vesicle formation. Finally, we give a short outlook on potential future developments in the field of crowded membrane systems. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Gernot Guigas
- Experimental Physics I, Universitaetsstr. 30, Bayreuth University, D-95440 Bayreuth, Germany
| | - Matthias Weiss
- Experimental Physics I, Universitaetsstr. 30, Bayreuth University, D-95440 Bayreuth, Germany.
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Tóth JT, Gulyás G, Tóth DJ, Balla A, Hammond GRV, Hunyady L, Balla T, Várnai P. BRET-monitoring of the dynamic changes of inositol lipid pools in living cells reveals a PKC-dependent PtdIns4P increase upon EGF and M3 receptor activation. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:177-87. [PMID: 26692031 DOI: 10.1016/j.bbalip.2015.12.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 11/18/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
Deciphering many roles played by inositol lipids in signal transduction and membrane function demands experimental approaches that can detect their dynamic accumulation with subcellular accuracy and exquisite sensitivity. The former criterion is met by imaging of fluorescence biosensors in living cells, whereas the latter is facilitated by biochemical measurements from populations. Here, we introduce BRET-based biosensors able to detect rapid changes in inositol lipids in cell populations with both high sensitivity and subcellular resolution in a single, convenient assay. We demonstrate robust and sensitive measurements of PtdIns4P, PtdIns(4,5)P2 and PtdIns(3,4,5)P3 dynamics, as well as changes in cytoplasmic Ins(1,4,5)P3 levels. Measurements were made during either experimental activation of lipid degradation, or PI 3-kinase and phospholipase C mediated signal transduction. Our results reveal a previously unappreciated synthesis of PtdIns4P that accompanies moderate activation of phospholipase C signaling downstream of both EGF and muscarinic M3 receptor activation. This signaling-induced PtdIns4P synthesis relies on protein kinase C, and implicates a feedback mechanism in the control of inositol lipid metabolism during signal transduction.
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Affiliation(s)
- József T Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Gergő Gulyás
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Dániel J Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Gerald R V Hammond
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Tamás Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary.
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43
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Phosphoinositide dynamics in the postsynaptic membrane compartment: Mechanisms and experimental approach. Eur J Cell Biol 2015; 94:401-14. [DOI: 10.1016/j.ejcb.2015.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Warren SC, Margineanu A, Katan M, Dunsby C, French PMW. Homo-FRET Based Biosensors and Their Application to Multiplexed Imaging of Signalling Events in Live Cells. Int J Mol Sci 2015; 16:14695-716. [PMID: 26133241 PMCID: PMC4519867 DOI: 10.3390/ijms160714695] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 06/15/2015] [Accepted: 06/17/2015] [Indexed: 12/20/2022] Open
Abstract
Multiplexed imaging of Förster Resonance Energy Transfer (FRET)-based biosensors potentially presents a powerful approach to monitoring the spatio-temporal correlation of signalling pathways within a single live cell. Here, we discuss the potential of homo-FRET based biosensors to facilitate multiplexed imaging. We demonstrate that the homo-FRET between pleckstrin homology domains of Akt (Akt-PH) labelled with mCherry may be used to monitor 3'-phosphoinositide accumulation in live cells and show how global analysis of time resolved fluorescence anisotropy measurements can be used to quantify this accumulation. We further present multiplexed imaging readouts of calcium concentration, using fluorescence lifetime measurements of TN-L15-a CFP/YFP based hetero-FRET calcium biosensor-with 3'-phosphoinositide accumulation.
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Affiliation(s)
- Sean C Warren
- Photonics Group, Department of Physics, Imperial College London, London SW7 2AZ, UK.
| | - Anca Margineanu
- Photonics Group, Department of Physics, Imperial College London, London SW7 2AZ, UK.
| | - Matilda Katan
- Structural and Molecular Biology, University College London, London WC1E 6BT, UK.
| | - Chris Dunsby
- Photonics Group, Department of Physics, Imperial College London, London SW7 2AZ, UK.
| | - Paul M W French
- Photonics Group, Department of Physics, Imperial College London, London SW7 2AZ, UK.
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45
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Kaur G, Pinggera A, Ortner NJ, Lieb A, Sinnegger-Brauns MJ, Yarov-Yarovoy V, Obermair GJ, Flucher BE, Striessnig J. A Polybasic Plasma Membrane Binding Motif in the I-II Linker Stabilizes Voltage-gated CaV1.2 Calcium Channel Function. J Biol Chem 2015; 290:21086-21100. [PMID: 26100638 PMCID: PMC4543666 DOI: 10.1074/jbc.m115.645671] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 12/27/2022] Open
Abstract
L-type voltage-gated Ca(2+) channels (LTCCs) regulate many physiological functions like muscle contraction, hormone secretion, gene expression, and neuronal excitability. Their activity is strictly controlled by various molecular mechanisms. The pore-forming α1-subunit comprises four repeated domains (I-IV), each connected via an intracellular linker. Here we identified a polybasic plasma membrane binding motif, consisting of four arginines, within the I-II linker of all LTCCs. The primary structure of this motif is similar to polybasic clusters known to interact with polyphosphoinositides identified in other ion channels. We used de novo molecular modeling to predict the conformation of this polybasic motif, immunofluorescence microscopy and live cell imaging to investigate the interaction with the plasma membrane, and electrophysiology to study its role for Cav1.2 channel function. According to our models, this polybasic motif of the I-II linker forms a straight α-helix, with the positive charges facing the lipid phosphates of the inner leaflet of the plasma membrane. Membrane binding of the I-II linker could be reversed after phospholipase C activation, causing polyphosphoinositide breakdown, and was accelerated by elevated intracellular Ca(2+) levels. This indicates the involvement of negatively charged phospholipids in the plasma membrane targeting of the linker. Neutralization of four arginine residues eliminated plasma membrane binding. Patch clamp recordings revealed facilitated opening of Cav1.2 channels containing these mutations, weaker inhibition by phospholipase C activation, and reduced expression of channels (as quantified by ON-gating charge) at the plasma membrane. Our data provide new evidence for a membrane binding motif within the I-II linker of LTCC α1-subunits essential for stabilizing normal Ca(2+) channel function.
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Affiliation(s)
- Gurjot Kaur
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Alexandra Pinggera
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Nadine J Ortner
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Andreas Lieb
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Martina J Sinnegger-Brauns
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, UC Davis School of Medicine, Davis, California 95616
| | - Gerald J Obermair
- Division of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Bernhard E Flucher
- Division of Physiology, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Jörg Striessnig
- Institute of Pharmacy, Department of Pharmacology and Toxicology, and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria.
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Bartlett PJ, Metzger W, Gaspers LD, Thomas AP. Differential Regulation of Multiple Steps in Inositol 1,4,5-Trisphosphate Signaling by Protein Kinase C Shapes Hormone-stimulated Ca2+ Oscillations. J Biol Chem 2015; 290:18519-33. [PMID: 26078455 DOI: 10.1074/jbc.m115.657767] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Indexed: 11/06/2022] Open
Abstract
How Ca(2+) oscillations are generated and fine-tuned to yield versatile downstream responses remains to be elucidated. In hepatocytes, G protein-coupled receptor-linked Ca(2+) oscillations report signal strength via frequency, whereas Ca(2+) spike amplitude and wave velocity remain constant. IP3 uncaging also triggers oscillatory Ca(2+) release, but, in contrast to hormones, Ca(2+) spike amplitude, width, and wave velocity were dependent on [IP3] and were not perturbed by phospholipase C (PLC) inhibition. These data indicate that oscillations elicited by IP3 uncaging are driven by the biphasic regulation of the IP3 receptor by Ca(2+), and, unlike hormone-dependent responses, do not require PLC. Removal of extracellular Ca(2+) did not perturb Ca(2+) oscillations elicited by IP3 uncaging, indicating that reloading of endoplasmic reticulum stores via plasma membrane Ca(2+) influx does not entrain the signal. Activation and inhibition of PKC attenuated hormone-induced Ca(2+) oscillations but had no effect on Ca(2+) increases induced by uncaging IP3. Importantly, PKC activation and inhibition differentially affected Ca(2+) spike frequencies and kinetics. PKC activation amplifies negative feedback loops at the level of G protein-coupled receptor PLC activity and/or IP3 metabolism to attenuate IP3 levels and suppress the generation of Ca(2+) oscillations. Inhibition of PKC relieves negative feedback regulation of IP3 accumulation and, thereby, shifts Ca(2+) oscillations toward sustained responses or dramatically prolonged spikes. PKC down-regulation attenuates phenylephrine-induced Ca(2+) wave velocity, whereas responses to IP3 uncaging are enhanced. The ability to assess Ca(2+) responses in the absence of PLC activity indicates that IP3 receptor modulation by PKC regulates Ca(2+) release and wave velocity.
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Affiliation(s)
- Paula J Bartlett
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
| | - Walson Metzger
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
| | - Lawrence D Gaspers
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
| | - Andrew P Thomas
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
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Kim YJ, Guzman-Hernandez ML, Wisniewski E, Balla T. Phosphatidylinositol-Phosphatidic Acid Exchange by Nir2 at ER-PM Contact Sites Maintains Phosphoinositide Signaling Competence. Dev Cell 2015; 33:549-61. [PMID: 26028218 DOI: 10.1016/j.devcel.2015.04.028] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 03/20/2015] [Accepted: 04/28/2015] [Indexed: 11/30/2022]
Abstract
Sustained agonist-induced production of the second messengers InsP3 and diacylglycerol requires steady delivery of phosphatidylinositol (PtdIns) from its site of synthesis in the ER to the plasma membrane (PM) to maintain PtdIns(4,5)P2 levels. Similarly, phosphatidic acid (PtdOH), generated from diacylglycerol in the PM, has to reach the ER for PtdIns resynthesis. Here, we show that the Drosophila RdgB homolog, Nir2, a presumed PtdIns transfer protein, not only transfers PtdIns from the ER to the PM but also transfers PtdOH to the opposite direction at ER-PM contact sites. PtdOH delivery to the ER is impaired in Nir2-depleted cells, leading to limited PtdIns synthesis and ultimately to loss of signaling from phospholipase C-coupled receptors. These studies reveal a unique feature of Nir2, namely its ability to serve as a highly localized lipid exchanger that ensures that PtdIns synthesis is matched with PtdIns(4,5)P2 utilization so that cells maintain their signaling competence.
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Affiliation(s)
- Yeun Ju Kim
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Maria-Luisa Guzman-Hernandez
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Eva Wisniewski
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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48
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Berthier C, Kutchukian C, Bouvard C, Okamura Y, Jacquemond V. Depression of voltage-activated Ca2+ release in skeletal muscle by activation of a voltage-sensing phosphatase. J Gen Physiol 2015; 145:315-30. [PMID: 25825170 PMCID: PMC4380211 DOI: 10.1085/jgp.201411309] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 03/05/2015] [Indexed: 12/30/2022] Open
Abstract
Phosphoinositides act as signaling molecules in numerous cellular transduction processes, and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) regulates the function of several types of plasma membrane ion channels. We investigated the potential role of PtdIns(4,5)P2 in Ca(2+) homeostasis and excitation-contraction (E-C) coupling of mouse muscle fibers using in vivo expression of the voltage-sensing phosphatases (VSPs) Ciona intestinalis VSP (Ci-VSP) or Danio rerio VSP (Dr-VSP). Confocal images of enhanced green fluorescent protein-tagged Dr-VSP revealed a banded pattern consistent with VSP localization within the transverse tubule membrane. Rhod-2 Ca(2+) transients generated by 0.5-s-long voltage-clamp depolarizing pulses sufficient to elicit Ca(2+) release from the sarcoplasmic reticulum (SR) but below the range at which VSPs are activated were unaffected by the presence of the VSPs. However, in Ci-VSP-expressing fibers challenged by 5-s-long depolarizing pulses, the Ca(2+) level late in the pulse (3 s after initiation) was significantly lower at 120 mV than at 20 mV. Furthermore, Ci-VSP-expressing fibers showed a reversible depression of Ca(2+) release during trains, with the peak Ca(2+) transient being reduced by ∼30% after the application of 10 200-ms-long pulses to 100 mV. A similar depression was observed in Dr-VSP-expressing fibers. Cav1.1 Ca(2+) channel-mediated current was unaffected by Ci-VSP activation. In fibers expressing Ci-VSP and a pleckstrin homology domain fused with monomeric red fluorescent protein (PLCδ1PH-mRFP), depolarizing pulses elicited transient changes in mRFP fluorescence consistent with release of transverse tubule-bound PLCδ1PH domain into the cytosol; the voltage sensitivity of these changes was consistent with that of Ci-VSP activation, and recovery occurred with a time constant in the 10-s range. Our results indicate that the PtdIns(4,5)P2 level is tightly maintained in the transverse tubule membrane of the muscle fibers, and that VSP-induced depletion of PtdIns(4,5)P2 impairs voltage-activated Ca(2+) release from the SR. Because Ca(2+) release is thought to be independent from InsP3 signaling, the effect likely results from an interaction between PtdIns(4,5)P2 and a protein partner of the E-C coupling machinery.
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Affiliation(s)
- Christine Berthier
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
| | - Candice Kutchukian
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
| | - Clément Bouvard
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
| | - Yasushi Okamura
- Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Vincent Jacquemond
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
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Mavrantoni A, Thallmair V, Leitner MG, Schreiber DN, Oliver D, Halaszovich CR. A method to control phosphoinositides and to analyze PTEN function in living cells using voltage sensitive phosphatases. Front Pharmacol 2015; 6:68. [PMID: 25873899 PMCID: PMC4379879 DOI: 10.3389/fphar.2015.00068] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/14/2015] [Indexed: 11/20/2022] Open
Abstract
Voltage sensitive phosphatases (VSPs), including engineered voltage sensitive PTEN, are excellent tools to rapidly and reversibly alter the phosphoinositide (PI) content of the plasma membrane in vivo and study the tumor suppressor PTEN. However, widespread adoption of these tools is hampered by the requirement for electrophysiological instrumentation to control the activity of VSPs. Additionally, monitoring and quantifying the PI changes in living cells requires sophisticated microscopy equipment and image analysis. Here we present methods that bypass these obstacles. First, we explore technically simple means for activation of VSPs via extracellularly applied agents or light. Secondly, we characterize methods to monitor PI(4,5)P2 and PI(3,4,5)P3 levels using fluorescence microscopy or photometry in conjunction with translocation or FRET based PI probes, respectively. We then demonstrate the application of these techniques by characterizing the effect of known PTEN mutations on its enzymatic activity, analyzing the effect of PTEN inhibitors, and detecting in real time rapid inhibition of protein kinase B following depletion of PI(3,4,5)P3. Thus, we established an approach that does not only allow for rapidly manipulating and monitoring PI(4,5)P2 and PI(3,4,5)P3 levels in a population of cells, but also facilitates the study of PTEN mutants and pharmacological targeting in mammalian cells.
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Affiliation(s)
- Angeliki Mavrantoni
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
| | - Veronika Thallmair
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
| | - Michael G Leitner
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
| | - Daniela N Schreiber
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
| | - Christian R Halaszovich
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
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Schifferer M, Feng S, Stein F, Tischer C, Schultz C. Reversible chemical dimerizer-induced recovery of PIP2 levels moves clathrin to the plasma membrane. Bioorg Med Chem 2015; 23:2862-7. [PMID: 25840797 DOI: 10.1016/j.bmc.2015.03.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/16/2015] [Accepted: 03/18/2015] [Indexed: 12/24/2022]
Abstract
Chemical dimerizers are powerful non-invasive tools for bringing molecules together inside intact cells. We recently introduced a rapidly reversible chemical dimerizer system which enables transient translocation of enzymes to and from the plasma membrane (PM). Here we have applied this system to transiently activate phosphatidylinositol 4,5-bisphosphate (PIP2) breakdown at the PM via translocation of phosphoinositide 5-phosphatase (5Ptase). We found that the PIP2 sensor phospholipase C-δ PH domain (PLCδ-PH) is released from the PM upon addition of the reversible chemical dimerizer rCD1. By outcompeting rCD1, rapid release of the 5Ptase from the PM is followed by PIP2 recovery. This permits the observation of the PIP2-dependent clathrin assembly at the PM.
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Affiliation(s)
- Martina Schifferer
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Suihan Feng
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Frank Stein
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Christian Tischer
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany.
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