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Pacheco J, Cassidy AC, Zewe JP, Wills RC, Hammond GR. PI(4,5)P2 diffuses freely in the plasma membrane even within high-density effector protein complexes. J Cell Biol 2023; 222:e202204099. [PMID: 36416724 PMCID: PMC9698391 DOI: 10.1083/jcb.202204099] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 08/11/2022] [Accepted: 11/04/2022] [Indexed: 11/24/2022] Open
Abstract
The lipid phosphatidyl-D-myo-inositol-4,5-bisphosphate [PI(4,5)P2] is a master regulator of plasma membrane (PM) function. Its effector proteins regulate transport, signaling, and cytoskeletal processes that define PM structure and function. How a single type of lipid regulates so many parallel processes is unclear. We tested the hypothesis that spatially separate PI(4,5)P2 pools associate with different PM complexes. The mobility of PI(4,5)P2 was measured using biosensors by single-particle tracking. We found that PM lipids including PI(4,5)P2 diffuse rapidly (∼0.3 µm2/s) with Brownian motion, although they spend one third of their time diffusing more slowly. Surprisingly, areas of the PM occupied by PI(4,5)P2-dependent complexes did not slow PI(4,5)P2 lateral mobility. Only the spectrin and septin cytoskeletons showed reduced PI(4,5)P2 diffusion. We conclude that even structures with high densities of PI(4,5)P2 effector proteins, such as clathrin-coated pits and focal adhesions, do not corral unbound PI(4,5)P2, questioning a role for spatially segregated PI(4,5)P2 pools in organizing and regulating PM functions.
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Affiliation(s)
- Jonathan Pacheco
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Anna C. Cassidy
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - James P. Zewe
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Rachel C. Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Gerald R.V. Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
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2
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Localisation of Intracellular Signals and Responses during Phagocytosis. Int J Mol Sci 2023; 24:ijms24032825. [PMID: 36769146 PMCID: PMC9917157 DOI: 10.3390/ijms24032825] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/22/2023] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Phagocytosis is one of the most polarised of all cellular activities. Both the stimulus (the target for phagocytosis) and the response (its internalisation) are focussed at just one part of the cell. At the locus, and this locus alone, pseudopodia form a phagocytic cup around the particle, the cytoskeleton is rearranged, the plasma membrane is reorganised, and a new internal organelle, the phagosome, is formed. The effect of signals from the stimulus must, thus, both be complex and yet be restricted in space and time to enable an effective focussed response. While many aspects of phagocytosis are being uncovered, the mechanism for the restriction of signalling or the effects of signalling remains obscure. In this review, the details of the problem of restricting chemical intracellular signalling are presented, with a focus on diffusion into the cytosol and of signalling lipids along the plasma membrane. The possible ways in which simple diffusion is overcome so that the restriction of signalling and effective phagocytosis can be achieved are discussed in the light of recent advances in imaging, biophysics, and cell biochemistry which together are providing new insights into this area.
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3
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Santamaria A, Carrascosa-Tejedor J, Guzmán E, Zaccai NR, Maestro A. Unravelling the orientation of the inositol-biphosphate ring and its dependence on phosphatidylinositol 4,5-bisphosphate cluster formation in model membranes. J Colloid Interface Sci 2023; 629:785-795. [PMID: 36195018 DOI: 10.1016/j.jcis.2022.09.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/03/2022] [Accepted: 09/18/2022] [Indexed: 10/14/2022]
Abstract
HYPOTHESIS Inositol phospholipids are well known to form clusters in the cytoplasmic leaflet of the plasma membrane that are responsible for the interaction and recruitment of proteins involved in key biological processes like endocytosis, ion channel activation and secondary messenger production. Although their phosphorylated inositol ring headgroup plays an important role in protein binding, its orientation with respect to the plane of the membrane and its lateral packing density has not been previously described experimentally. EXPERIMENTS Here, we study phosphatidylinositol 4,5-bisphosphate (PIP2) planar model membranes in the form of Langmuir monolayers by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry to elucidate the relation between lateral (in-plane) and perpendicular (out-of-plane) molecular organization of PIP2. FINDINGS Different surface areas were explored through monolayer compression, allowing us to correlate the formation of transient PIP2 clusters with the change in orientation of the inositol-biphosphate headgroup, which was experimentally determined by neutron reflectometry.
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Affiliation(s)
- Andreas Santamaria
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Javier Carrascosa-Tejedor
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Eduardo Guzmán
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain; Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII 1, 28040 Madrid, Spain.
| | - Nathan R Zaccai
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB22 7QQ, United Kingdom.
| | - Armando Maestro
- Centro de Fı́sica de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain; IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain.
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4
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Yue Q, Al-Khalili O, Moseley A, Yoshigi M, Wynne BM, Ma H, Eaton DC. PIP 2 Interacts Electrostatically with MARCKS-like Protein-1 and ENaC in Renal Epithelial Cells. BIOLOGY 2022; 11:biology11121694. [PMID: 36552204 PMCID: PMC9774185 DOI: 10.3390/biology11121694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/30/2022] [Accepted: 10/17/2022] [Indexed: 11/25/2022]
Abstract
We examined the interaction of a membrane-associated protein, MARCKS-like Protein-1 (MLP-1), and an ion channel, Epithelial Sodium Channel (ENaC), with the anionic lipid, phosphatidylinositol 4, 5-bisphosphate (PIP2). We found that PIP2 strongly activates ENaC in excised, inside-out patches with a half-activating concentration of 21 ± 1.17 µM. We have identified 2 PIP2 binding sites in the N-terminus of ENaC β and γ with a high concentration of basic residues. Normal channel activity requires MLP-1's strongly positively charged effector domain to electrostatically sequester most of the membrane PIP2 and increase the local concentration of PIP2. Our previous data showed that ENaC covalently binds MLP-1 so PIP2 bound to MLP-1 would be near PIP2 binding sites on the cytosolic N terminal regions of ENaC. We have modified the charge structure of the PIP2 -binding domains of MLP-1 and ENaC and showed that the changes affect membrane localization and ENaC activity in a way consistent with electrostatic theory.
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Affiliation(s)
- Qiang Yue
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Otor Al-Khalili
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Auriel Moseley
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Masaaki Yoshigi
- Division of Nephrology & Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | - Brandi Michele Wynne
- Division of Nephrology & Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | - Heping Ma
- Department of Physiology, Emory University, Atlanta, GA 30322, USA
| | - Douglas C. Eaton
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- Correspondence: ; Tel.: +1-404-727-4533; Fax: +1-404-727-3425
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5
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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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6
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Compartmentalization of phosphatidylinositol 4,5-bisphosphate metabolism into plasma membrane liquid-ordered/raft domains. Proc Natl Acad Sci U S A 2021; 118:2025343118. [PMID: 33619111 DOI: 10.1073/pnas.2025343118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Possible segregation of plasma membrane (PM) phosphoinositide metabolism in membrane lipid domains is not fully understood. We exploited two differently lipidated peptide sequences, L10 and S15, to mark liquid-ordered, cholesterol-rich (Lo) and liquid-disordered, cholesterol-poor (Ld) domains of the PM, often called raft and nonraft domains, respectively. Imaging of the fluorescent labels verified that L10 segregated into cholesterol-rich Lo phases of cooled giant plasma-membrane vesicles (GPMVs), whereas S15 and the dye FAST DiI cosegregated into cholesterol-poor Ld phases. The fluorescent protein markers were used as Förster resonance energy transfer (FRET) pairs in intact cells. An increase of homologous FRET between L10 probes showed that depleting membrane cholesterol shrank Lo domains and enlarged Ld domains, whereas a decrease of L10 FRET showed that adding more cholesterol enlarged Lo and shrank Ld Heterologous FRET signals between the lipid domain probes and phosphoinositide marker proteins suggested that phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P 2] and phosphatidylinositol 4-phosphate (PtdIns4P) are present in both Lo and Ld domains. In kinetic analysis, muscarinic-receptor-activated phospholipase C (PLC) depleted PtdIns(4,5)P 2 and PtdIns4P more rapidly and produced diacylglycerol (DAG) more rapidly in Lo than in Ld Further, PtdIns(4,5)P 2 was restored more rapidly in Lo than in Ld Thus destruction and restoration of PtdIns(4,5)P 2 are faster in Lo than in Ld This suggests that Lo is enriched with both the receptor G protein/PLC pathway and the PtdIns/PI4-kinase/PtdIns4P pathway. The significant kinetic differences of lipid depletion and restoration also mean that exchange of lipids between these domains is much slower than free diffusion predicts.
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7
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Han K, Gericke A, Pastor RW. Characterization of Specific Ion Effects on PI(4,5)P 2 Clustering: Molecular Dynamics Simulations and Graph-Theoretic Analysis. J Phys Chem B 2020; 124:1183-1196. [PMID: 31994887 PMCID: PMC7461730 DOI: 10.1021/acs.jpcb.9b10951] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Numerous cellular functions mediated by phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2; PIP2) involve clustering of the lipid as well as colocalization with other lipids. Although the cation-mediated electrostatic interaction is regarded as the primary clustering mechanism, the ion-specific nature of the intermolecular network formation makes it challenging to characterize the clusters. Here we use all-atom molecular dynamics (MD) simulations of PIP2 monolayers and graph-theoretic analysis to gain insight into the phenomenon. MD simulations reveal that the intermolecular interactions preferentially occur between specific cations and phosphate groups (P1, P4, and P5) of the inositol headgroup with better-matched kosmotropic/chaotropic characters consistent with the law of matching water affinities (LMWA). Ca2+ is strongly attracted to P4/P5, while K+ preferentially binds to P1; Na+ interacts with both P4/P5 and P1. These specific interactions lead to the characteristic clustering patterns. Specificially, the size distributions and structures of PIP2 clusters generated by kosmotropic cations Ca2+ and Na+ are bimodal, with a combination of small and large clusters, while there is little clustering in the presence of only chaotropic K+; the largest clusters are obtained in systems with all three cations. The small-world network (a model with both local and long-range connections) best characterizes the clusters, followed by the random and the scale-free networks. More generally, the present results interpreted within the LMWA are consistent with the relative eukaryotic intracellular concentrations Ca2+ ≪ Na+ < Mg2+ < K+; that is, concentrations of Ca2+ and Na+ must be low to prevent damaging aggregation of lipids, DNA, RNA and phosphate-containing proteins.
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Affiliation(s)
- Kyungreem Han
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, 01609, USA
| | - Richard W. Pastor
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
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8
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Bag N, Holowka DA, Baird BA. Imaging FCS delineates subtle heterogeneity in plasma membranes of resting mast cells. Mol Biol Cell 2020; 31:709-723. [PMID: 31895009 PMCID: PMC7202073 DOI: 10.1091/mbc.e19-10-0559] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A myriad of transient, nanoscopic lipid- and protein-based interactions confer a steady-state organization of the plasma membrane in resting cells that is poised to orchestrate assembly of key signaling components upon reception of an extracellular stimulus. Although difficult to observe directly in live cells, these subtle interactions can be discerned by their impact on the diffusion of membrane constituents. Here, we quantified the diffusion properties of a panel of structurally distinct lipid, lipid-anchored, and transmembrane (TM) probes in RBL mast cells by imaging fluorescence correlation spectroscopy (ImFCS). We developed a statistical analysis of data combined from many pixels over multiple cells to characterize differences in diffusion coefficients as small as 10%, which reflect differences in underlying interactions. We found that the distinctive diffusion properties of lipid probes can be explained by their dynamic partitioning into Lo-like proteolipid nanodomains, which encompass a major fraction of the membrane and whose physical properties are influenced by actin polymerization. Effects on diffusion of functional protein modules in both lipid-anchored and TM probes reflect additional complexity in steady state membrane organization. The contrast we observe between different probes diffusing through the same membrane milieu represents the dynamic resting steady state, which serves as a baseline for monitoring plasma membrane remodeling that occurs upon stimulation.
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Affiliation(s)
- Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
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9
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Ghysels A, Krämer A, Venable RM, Teague WE, Lyman E, Gawrisch K, Pastor RW. Permeability of membranes in the liquid ordered and liquid disordered phases. Nat Commun 2019; 10:5616. [PMID: 31819053 PMCID: PMC6901538 DOI: 10.1038/s41467-019-13432-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/06/2019] [Indexed: 11/09/2022] Open
Abstract
The functional significance of ordered nanodomains (or rafts) in cholesterol rich eukaryotic cell membranes has only begun to be explored. This study exploits the correspondence of cellular rafts and liquid ordered (Lo) phases of three-component lipid bilayers to examine permeability. Molecular dynamics simulations of Lo phase dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), and cholesterol show that oxygen and water transit a leaflet through the DOPC and cholesterol rich boundaries of hexagonally packed DPPC microdomains, freely diffuse along the bilayer midplane, and escape the membrane along the boundary regions. Electron paramagnetic resonance experiments provide critical validation: the measured ratio of oxygen concentrations near the midplanes of liquid disordered (Ld) and Lo bilayers of DPPC/DOPC/cholesterol is 1.75 ± 0.35, in very good agreement with 1.3 ± 0.3 obtained from simulation. The results show how cellular rafts can be structurally rigid signaling platforms while remaining nearly as permeable to small molecules as the Ld phase.
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Affiliation(s)
- An Ghysels
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052, Gent, Belgium.
| | - Andreas Krämer
- Laboratory of Computational Biology, National Heart Lung Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Richard M Venable
- Laboratory of Computational Biology, National Heart Lung Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Walter E Teague
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Edward Lyman
- Department of Physics and Astronomy and Department of Chemistry and Biochemistry, University of Delaware, Newark, 19716, DE, USA
| | - Klaus Gawrisch
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart Lung Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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10
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Hansen SD, Huang WYC, Lee YK, Bieling P, Christensen SM, Groves JT. Stochastic geometry sensing and polarization in a lipid kinase-phosphatase competitive reaction. Proc Natl Acad Sci U S A 2019; 116:15013-15022. [PMID: 31278151 PMCID: PMC6660746 DOI: 10.1073/pnas.1901744116] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Phosphorylation reactions, driven by competing kinases and phosphatases, are central elements of cellular signal transduction. We reconstituted a native eukaryotic lipid kinase-phosphatase reaction that drives the interconversion of phosphatidylinositol-4-phosphate [PI(4)P] and phosphatidylinositol-4,5-phosphate [PI(4,5)P2] on membrane surfaces. This system exhibited bistability and formed spatial composition patterns on supported membranes. In smaller confined regions of membrane, rapid diffusion ensures the system remains spatially homogeneous, but the final outcome-a predominantly PI(4)P or PI(4,5)P2 membrane composition-was governed by the size of the reaction environment. In larger confined regions, interplay between the reactions, diffusion, and confinement created a variety of differentially patterned states, including polarization. Experiments and kinetic modeling reveal how these geometric confinement effects arise from a mechanism based on stochastic fluctuations in the copy number of membrane-bound kinases and phosphatases. The underlying requirements for such behavior are unexpectedly simple and likely to occur in natural biological signaling systems.
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Affiliation(s)
- Scott D Hansen
- Department of Chemistry, University of California, Berkeley, CA 94720;
- California Institute for Quantitative Biosciences, Berkeley, CA 94720
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403
| | - William Y C Huang
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Young Kwang Lee
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Peter Bieling
- California Institute for Quantitative Biosciences, Berkeley, CA 94720
| | | | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, CA 94720;
- California Institute for Quantitative Biosciences, Berkeley, CA 94720
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11
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Abstract
In macropinocytosis, cells take up micrometre-sized droplets of medium into internal vesicles. These vesicles are acidified and fused to lysosomes, their contents digested and useful compounds extracted. Indigestible contents can be exocytosed. Macropinocytosis has been known for approaching 100 years and is described in both metazoa and amoebae, but not in plants or fungi. Its evolutionary origin goes back to at least the common ancestor of the amoebozoa and opisthokonts, with apparent secondary loss from fungi. The primary function of macropinocytosis in amoebae and some cancer cells is feeding, but the conserved processing pathway for macropinosomes, which involves shrinkage and the retrieval of membrane to the cell surface, has been adapted in immune cells for antigen presentation. Macropinocytic cups are large actin-driven processes, closely related to phagocytic cups and pseudopods and appear to be organized around a conserved signalling patch of PIP3, active Ras and active Rac that directs actin polymerization to its periphery. Patches can form spontaneously and must be sustained by excitable kinetics with strong cooperation from the actin cytoskeleton. Growth-factor signalling shares core components with macropinocytosis, based around phosphatidylinositol 3-kinase (PI3-kinase), and we suggest that it evolved to take control of ancient feeding structures through a coupled growth factor receptor. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
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Affiliation(s)
- Jason S. King
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Robert R. Kay
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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12
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Curthoys NM, Mlodzianoski MJ, Parent M, Butler MB, Raut P, Wallace J, Lilieholm J, Mehmood K, Maginnis MS, Waters H, Busse B, Zimmerberg J, Hess ST. Influenza Hemagglutinin Modulates Phosphatidylinositol 4,5-Bisphosphate Membrane Clustering. Biophys J 2019; 116:893-909. [PMID: 30773293 DOI: 10.1016/j.bpj.2019.01.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 01/07/2019] [Accepted: 01/15/2019] [Indexed: 12/13/2022] Open
Abstract
The lipid phosphatidylinositol 4,5-bisphosphate (PIP2) forms nanoscopic clusters in cell plasma membranes; however, the processes determining PIP2 mobility and thus its spatial patterns are not fully understood. Using super-resolution imaging of living cells, we find that PIP2 is tightly colocalized with and modulated by overexpression of the influenza viral protein hemagglutinin (HA). Within and near clusters, HA and PIP2 follow a similar spatial dependence, which can be described by an HA-dependent potential gradient; PIP2 molecules move as if they are attracted to the center of clusters by a radial force of 0.079 ± 0.002 pN in HAb2 cells. The measured clustering and dynamics of PIP2 are inconsistent with the unmodified forms of the raft, tether, and fence models. Rather, we found that the spatial PIP2 distributions and how they change in time are explained via a novel, to our knowledge, dynamic mechanism: a radial gradient of PIP2 binding sites that are themselves mobile. This model may be useful for understanding other biological membrane domains whose distributions display gradients in density while maintaining their mobility.
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Affiliation(s)
- Nikki M Curthoys
- Department of Physics and Astronomy, University of Maine, Orono, Maine
| | | | - Matthew Parent
- Department of Physics and Astronomy, University of Maine, Orono, Maine
| | - Michael B Butler
- Department of Physics and Astronomy, University of Maine, Orono, Maine
| | - Prakash Raut
- Department of Physics and Astronomy, University of Maine, Orono, Maine
| | - Jaqulin Wallace
- Department of Physics and Astronomy, University of Maine, Orono, Maine
| | | | - Kashif Mehmood
- Department of Physics and Astronomy, University of Maine, Orono, Maine; Department of Molecular and Biomedical Sciences, University of Maine, Orono, Maine
| | - Melissa S Maginnis
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, Maine
| | - Hang Waters
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Brad Busse
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Samuel T Hess
- Department of Physics and Astronomy, University of Maine, Orono, Maine.
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13
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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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14
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Abbineni PS, Axelrod D, Holz RW. Visualization of expanding fusion pores in secretory cells. J Gen Physiol 2018; 150:1640-1646. [PMID: 30470717 PMCID: PMC6279363 DOI: 10.1085/jgp.201812186] [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: 07/24/2018] [Accepted: 11/06/2018] [Indexed: 11/20/2022] Open
Abstract
Abbineni et al. examine recent imaging work on fusion pores and discuss the dynamics of PI-4,5-P2 accumulation on granule membranes.
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Affiliation(s)
- Prabhodh S Abbineni
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Daniel Axelrod
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI .,Department of Physics and LSA Biophysics, University of Michigan Medical School, Ann Arbor, MI
| | - Ronald W Holz
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
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15
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Wang JB, Gu Y, Zhang MX, Yang S, Wang Y, Wang W, Li XR, Zhao YT, Wang HT. High expression of type I inositol 1,4,5-trisphosphate receptor in the kidney of rats with hepatorenal syndrome. World J Gastroenterol 2018; 24:3273-3280. [PMID: 30090007 PMCID: PMC6079285 DOI: 10.3748/wjg.v24.i29.3273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/19/2018] [Accepted: 06/27/2018] [Indexed: 02/06/2023] Open
Abstract
AIM To detect the expression of type I inositol 1,4,5-trisphosphate receptor (IP3RI) in the kidney of rats with hepatorenal syndrome (HRS). METHODS One hundred and twenty-five Sprague-Dawley rats were randomly divided into four groups to receive an intravenous injection of D-galactosamine (D-GalN) plus lipopolysaccharide (LPS; group G/L, n = 50), D-GalN alone (group G, n = 25), LPS alone (group L, n = 25), and normal saline (group NS, n = 25), respectively. At 3, 6, 9, 12, and 24 h after injection, blood, liver, and kidney samples were collected. Hematoxylin-eosin staining of liver tissue was performed to assess hepatocyte necrosis. Electron microscopy was used to observe ultrastructural changes in the kidney. Western blot analysis and real-time PCR were performed to detect the expression of IP3RI protein and mRNA in the kidney, respectively. RESULTS Hepatocyte necrosis was aggravated gradually, which was most significant at 12 h after treatment with D-galactosamine/lipopolysaccharide, and was characterized by massive hepatocyte necrosis. At the same time, serum levels of biochemical indicators including liver and kidney function indexes were all significantly changed. The structure of the renal glomerulus and tubules was normal at all time points. Western blot analysis indicated that IP3RI protein expression began to rise at 3 h (P < 0.05) and peaked at 12 h (P < 0.01). Real-time PCR demonstrated that IP3RI mRNA expression began to rise at 3 h (P < 0.05) and peaked at 9 h (P < 0.01). CONCLUSION IP3RI protein expression is increased in the kidney of HRS rats, and may be regulated at the transcriptional level.
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MESH Headings
- Animals
- Disease Models, Animal
- Galactosamine/toxicity
- Hepatocytes/pathology
- Hepatorenal Syndrome/chemically induced
- Hepatorenal Syndrome/pathology
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Kidney/blood supply
- Kidney/cytology
- Kidney/pathology
- Kidney/ultrastructure
- Lipopolysaccharides/toxicity
- Liver/cytology
- Liver/drug effects
- Liver/pathology
- Male
- Microscopy, Electron
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/pathology
- Myocytes, Smooth Muscle/pathology
- Myocytes, Smooth Muscle/ultrastructure
- Necrosis
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Specific Pathogen-Free Organisms
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Affiliation(s)
- Jing-Bo Wang
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Ye Gu
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Ming-Xiang Zhang
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Shun Yang
- Liaoning Cancer Hospital & Institute, Shenyang 110042, Liaoning Province, China
| | - Yan Wang
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Wei Wang
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Xi-Ran Li
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Yi-Tong Zhao
- Liver Cirrhosis Ward, the Sixth People’s Hospital of Shenyang, Shenyang 110006, Liaoning Province, China
| | - Hai-Tao Wang
- Department of General Surgery, the Second Affiliated Hospital of Shenyang Medical College, Shenyang 110002, Liaoning Province, China
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16
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Lancaster CE, Ho CY, Hipolito VEB, Botelho RJ, Terebiznik MR. Phagocytosis: what's on the menu? 1. Biochem Cell Biol 2018; 97:21-29. [PMID: 29791809 DOI: 10.1139/bcb-2018-0008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phagocytosis is an evolutionarily conserved process. In Protozoa, phagocytosis fulfills a feeding mechanism, while in Metazoa, phagocytosis diversified to play multiple organismal roles, including immune defence, tissue homeostasis, and remodeling. Accordingly, phagocytes display a high level of plasticity in their capacity to recognize, engulf, and process targets that differ in composition and morphology. Here, we review how phagocytosis adapts to its multiple roles and discuss in particular the effect of target morphology in phagocytic uptake and phagosome maturation.
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Affiliation(s)
- Charlene E Lancaster
- a Department of Biological Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada.,b Department of Cell and System Biology, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
| | - Cheuk Y Ho
- a Department of Biological Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
| | - Victoria E B Hipolito
- c Molecular Science Graduate Program, Ryerson University, Toronto, ON M5B 2K3, Canada.,d Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roberto J Botelho
- c Molecular Science Graduate Program, Ryerson University, Toronto, ON M5B 2K3, Canada.,d Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Mauricio R Terebiznik
- a Department of Biological Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada.,b Department of Cell and System Biology, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
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17
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Choi S, Houdek X, Anderson RA. Phosphoinositide 3-kinase pathways and autophagy require phosphatidylinositol phosphate kinases. Adv Biol Regul 2018; 68:31-38. [PMID: 29472147 PMCID: PMC5955796 DOI: 10.1016/j.jbior.2018.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/07/2018] [Accepted: 02/07/2018] [Indexed: 01/10/2023]
Abstract
Phosphatidylinositol phosphate kinases (PIPKs) generate a lipid messenger phosphatidylinositol 4,5-bisphosphate (PI4,5P2) that controls essentially all aspects of cellular functions. PI4,5P2 rapidly diffuses in the membrane of the lipid bilayer and does not greatly change in membrane or cellular content, and thus PI4,5P2 generation by PIPKs is tightly linked to its usage in subcellular compartments. Based on this verity, recent study of PI4,5P2 signal transduction has been focused on investigations of individual PIPKs and their underlying molecular regulation of cellular processes. Here, we will discuss recent advances in the study of how PIPKs control specific cellular events through assembly and regulation of PI4,5P2 effectors that mediate specific cellular processes. A focus will be on the roles of PIPKs in control of the phosphoinositide 3-kinase pathway and autophagy.
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Affiliation(s)
- Suyong Choi
- University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Xander Houdek
- University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
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18
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The Sealing Zone in Osteoclasts: A Self-Organized Structure on the Bone. Int J Mol Sci 2018; 19:ijms19040984. [PMID: 29587415 PMCID: PMC5979552 DOI: 10.3390/ijms19040984] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/22/2018] [Accepted: 03/23/2018] [Indexed: 01/08/2023] Open
Abstract
Osteoclasts form a specialized cell-matrix adhesion structure, known as the "sealing zone", during bone resorption. The sealing zone is a dynamic actin-rich structure that defines the resorption area of the bone. The detailed dynamics and fine structure of the sealing zone have been elusive. Osteoclasts plated on glass do not form a sealing zone, but generate a separate supra-molecular structure called the "podosome belt". Podosomes are integrin-based adhesion complexes involved in matrix adhesion, cell migration, matrix degradation, and mechanosensing. Invadopodia, podosome-like protrusions in cancer cells, are involved in cell invasion into other tissues by promoting matrix degradation. Both podosomes and invadopodia exhibit actin pattern transitions during maturation. We previously found that Arp2/3-dependent actin flow occurs in all observed assembly patterns of podosomes in osteoclasts on glass. It is known that the actin wave in Dictyostelium cells exhibits a similar pattern transition in its evolution. Because of significant advances in our understanding regarding the mechanism of podosomes/invadopodia formation over the last decade, we revisited the structure and function of the sealing zone in this review, highlighting the possible involvement of self-organized actin waves in the organogenesis of the sealing zone.
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19
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Maxson ME, Naj X, O'Meara TR, Plumb JD, Cowen LE, Grinstein S. Integrin-based diffusion barrier separates membrane domains enabling the formation of microbiostatic frustrated phagosomes. eLife 2018; 7:34798. [PMID: 29553370 PMCID: PMC5897098 DOI: 10.7554/elife.34798] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/16/2018] [Indexed: 12/25/2022] Open
Abstract
Candida albicans hyphae can reach enormous lengths, precluding their internalization by phagocytes. Nevertheless, macrophages engulf a portion of the hypha, generating incompletely sealed tubular phagosomes. These frustrated phagosomes are stabilized by a thick cuff of F-actin that polymerizes in response to non-canonical activation of integrins by fungal glycan. Despite their continuity, the surface and invaginating phagosomal membranes retain a strikingly distinct lipid composition. PtdIns(4,5)P2 is present at the plasmalemma but is not detectable in the phagosomal membrane, while PtdIns(3)P and PtdIns(3,4,5)P3 co-exist in the phagosomes yet are absent from the surface membrane. Moreover, endo-lysosomal proteins are present only in the phagosomal membrane. Fluorescence recovery after photobleaching revealed the presence of a diffusion barrier that maintains the identity of the open tubular phagosome separate from the plasmalemma. Formation of this barrier depends on Syk, Pyk2/Fak and formin-dependent actin assembly. Antimicrobial mechanisms can thereby be deployed, limiting the growth of the hyphae.
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Affiliation(s)
- Michelle E Maxson
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
| | - Xenia Naj
- Institute for Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Teresa R O'Meara
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Jonathan D Plumb
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
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20
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Han K, Venable RM, Bryant AM, Legacy CJ, Shen R, Li H, Roux B, Gericke A, Pastor RW. Graph-Theoretic Analysis of Monomethyl Phosphate Clustering in Ionic Solutions. J Phys Chem B 2018; 122:1484-1494. [PMID: 29293344 DOI: 10.1021/acs.jpcb.7b10730] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
All-atom molecular dynamics simulations combined with graph-theoretic analysis reveal that clustering of monomethyl phosphate dianion (MMP2-) is strongly influenced by the types and combinations of cations in the aqueous solution. Although Ca2+ promotes the formation of stable and large MMP2- clusters, K+ alone does not. Nonetheless, clusters are larger and their link lifetimes are longer in mixtures of K+ and Ca2+. This "synergistic" effect depends sensitively on the Lennard-Jones interaction parameters between Ca2+ and the phosphorus oxygen and correlates with the hydration of the clusters. The pronounced MMP2- clustering effect of Ca2+ in the presence of K+ is confirmed by Fourier transform infrared spectroscopy. The characterization of the cation-dependent clustering of MMP2- provides a starting point for understanding cation-dependent clustering of phosphoinositides in cell membranes.
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Affiliation(s)
- Kyungreem Han
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Richard M Venable
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Anne-Marie Bryant
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States
| | - Christopher J Legacy
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States
| | - Rong Shen
- Department of Biochemistry and Molecular Biology, The University of Chicago , Chicago, Illinois 60637, United States
| | - Hui Li
- Department of Biochemistry and Molecular Biology, The University of Chicago , Chicago, Illinois 60637, United States
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, The University of Chicago , Chicago, Illinois 60637, United States
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
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21
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Hilgemann DW, Dai G, Collins A, Lariccia V, Magi S, Deisl C, Fine M. Lipid signaling to membrane proteins: From second messengers to membrane domains and adapter-free endocytosis. J Gen Physiol 2018; 150:211-224. [PMID: 29326133 PMCID: PMC5806671 DOI: 10.1085/jgp.201711875] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hilgemann et al. explain how lipid signaling to membrane proteins involves a hierarchy of mechanisms from lipid binding to membrane domain coalescence. Lipids influence powerfully the function of ion channels and transporters in two well-documented ways. A few lipids act as bona fide second messengers by binding to specific sites that control channel and transporter gating. Other lipids act nonspecifically by modifying the physical environment of channels and transporters, in particular the protein–membrane interface. In this short review, we first consider lipid signaling from this traditional viewpoint, highlighting innumerable Journal of General Physiology publications that have contributed to our present understanding. We then switch to our own emerging view that much important lipid signaling occurs via the formation of membrane domains that influence the function of channels and transporters within them, promote selected protein–protein interactions, and control the turnover of surface membrane.
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Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Gucan Dai
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Anthony Collins
- Saba University School of Medicine, The Bottom, Saba, Dutch Caribbean
| | - Vincenzo Lariccia
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche," Ancona, Italy
| | - Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche," Ancona, Italy
| | - Christine Deisl
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Michael Fine
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
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22
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Veerapathiran S, Wohland T. The imaging FCS diffusion law in the presence of multiple diffusive modes. Methods 2017; 140-141:140-150. [PMID: 29203404 DOI: 10.1016/j.ymeth.2017.11.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 01/21/2023] Open
Abstract
The cellular plasma membrane is the barrier over which cells exchange materials and communicate with their surroundings, and thus plays the central role in cellular sensing and metabolism. Therefore, the investigation of plasma membrane organization and dynamics is required for understanding of cellular functions. The plasma membrane is a heterogeneous matrix. The presence of structures such as lipid and protein domains and the cytoskeleton meshwork poses a hindrance to the free diffusion of membrane associated biomolecules. However, these domains and the cytoskeleton meshwork barriers are below the optical diffraction limit with potentially short lifetimes and are not easily detected even in super-resolution microscopy. Therefore, dynamic measurements are often used to indirectly prove the existence of domains and barriers by analyzing the mode of diffusion of probe molecules. One of these tools is the Fluorescence Correlation Spectroscopy (FCS) diffusion law. The FCS diffusion law is a plot of diffusion time (τd) versus observation area. For at least three different diffusive modes - free, domain confined, and meshwork hindered hop diffusion - the expected plots have been characterized, typically by its y-intercept (τ0) when fit with a linear model, and have been verified in many cases. However, a description of τ0 has only been given for pure diffusive modes. But in many experimental cases it is not evident that a protein will undergo only one kind of diffusion, and thus the interpretation of the τ0 value is problematic. Here, we therefore address the question about the absolute value of τ0 in the case of complex diffusive modes, i.e. when either one molecule is domain confined and cytoskeleton hindered or when two molecules exhibit different diffusive behavior at the same position in a sample. In addition, we investigate how τ0 changes when the diffusive mode of a probe alters upon disruption of domains or the cytoskeleton by drug treatments. By a combination of experimental studies and simulations, we show that τ0 is not influenced equally by the different diffusive modes as typically found in cellular environments, and that it is the relative change of τ0 rather than its absolute value that provides information on the mode of diffusion.
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Affiliation(s)
- Sapthaswaran Veerapathiran
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, 117557 Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, 117557 Singapore, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore.
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23
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Phosphatidylinositol (4,5)-bisphosphate-mediated pathophysiological effect of HIV-1 Tat protein. Biochimie 2017; 141:80-85. [DOI: 10.1016/j.biochi.2017.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/21/2017] [Indexed: 11/23/2022]
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24
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Buckley CM, King JS. Drinking problems: mechanisms of macropinosome formation and maturation. FEBS J 2017; 284:3778-3790. [DOI: 10.1111/febs.14115] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 04/25/2017] [Accepted: 05/17/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Catherine M. Buckley
- Department of Biomedical Sciences Centre for Membrane Interactions and Dynamics University of Sheffield UK
- Bateson Centre University of Sheffield UK
| | - Jason S. King
- Department of Biomedical Sciences Centre for Membrane Interactions and Dynamics University of Sheffield UK
- Bateson Centre University of Sheffield UK
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25
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Yandrapalli N, Lubart Q, Tanwar HS, Picart C, Mak J, Muriaux D, Favard C. Self assembly of HIV-1 Gag protein on lipid membranes generates PI(4,5)P 2/Cholesterol nanoclusters. Sci Rep 2016; 6:39332. [PMID: 28008947 PMCID: PMC5180241 DOI: 10.1038/srep39332] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 11/22/2016] [Indexed: 01/26/2023] Open
Abstract
The self-assembly of HIV-1 Gag polyprotein at the inner leaflet of the cell host plasma membrane is the key orchestrator of virus assembly. The binding between Gag and the plasma membrane is mediated by specific interaction of the Gag matrix domain and the PI(4,5)P2 lipid (PIP2). It is unknown whether this interaction could lead to local reorganization of the plasma membrane lipids. In this study, using model membranes, we examined the ability of Gag to segregate specific lipids upon self-assembly. We show for the first time that Gag self-assembly is responsible for the formation of PIP2 lipid nanoclusters, enriched in cholesterol but not in sphingomyelin. We also show that Gag mainly partition into liquid-disordered domains of these lipid membranes. Our work strongly suggests that, instead of targeting pre-existing plasma membrane lipid domains, Gag is more prone to generate PIP2/Cholesterol lipid nanodomains at the inner leaflet of the plasma membrane during early events of virus assembly.
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Affiliation(s)
- Naresh Yandrapalli
- CNRS-Université Montpellier, Centre d'études d'agents Pathogenes et de Biotechnologies pour la Santé, Montpellier, France
| | - Quentin Lubart
- CNRS-Université Grenoble, Institut National de Physique, Grenoble, France
| | | | - Catherine Picart
- CNRS-Université Grenoble, Institut National de Physique, Grenoble, France
| | - Johnson Mak
- Deakin University, School of Medicine, Melbourne, Australia
| | - Delphine Muriaux
- CNRS-Université Montpellier, Centre d'études d'agents Pathogenes et de Biotechnologies pour la Santé, Montpellier, France
| | - Cyril Favard
- CNRS-Université Montpellier, Centre d'études d'agents Pathogenes et de Biotechnologies pour la Santé, Montpellier, France
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26
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Huang S, Lim SY, Gupta A, Bag N, Wohland T. Plasma membrane organization and dynamics is probe and cell line dependent. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:1483-1492. [PMID: 27998689 DOI: 10.1016/j.bbamem.2016.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/03/2016] [Accepted: 12/08/2016] [Indexed: 01/01/2023]
Abstract
The action and interaction of membrane receptor proteins take place within the plasma membrane. The plasma membrane, however, is not a passive matrix. It rather takes an active role and regulates receptor distribution and function by its composition and the interaction of its lipid components with embedded and surrounding proteins. Furthermore, it is not a homogenous fluid but contains lipid and protein domains of various sizes and characteristic lifetimes which are important in regulating receptor function and signaling. The precise lateral organization of the plasma membrane, the differences between the inner and outer leaflet, and the influence of the cytoskeleton are still debated. Furthermore, there is a lack of comparisons of the organization and dynamics of the plasma membrane of different cell types. Therefore, we used four different specific membrane markers to test the lateral organization, the differences between the inner and outer membrane leaflet, and the influence of the cytoskeleton of up to five different cell lines, including Chinese hamster ovary (CHO-K1), Human cervical carcinoma (HeLa), neuroblastoma (SH-SY5Y), fibroblast (WI-38) and rat basophilic leukemia (RBL-2H3) cells by Imaging Total Internal Reflection (ITIR)-Fluorescence Correlation Spectroscopy (FCS). We measure diffusion in the temperature range of 298-310K to measure the Arrhenius activation energy (EArr) of diffusion and apply the FCS diffusion law to obtain information on the spatial organization of the probe molecules on the various cell membranes. Our results show clear differences of the FCS diffusion law and EArr for the different probes in dependence of their localization. These differences are similar in the outer and inner leaflet of the membrane. However, these values can differ significantly between different cell lines raising the question how molecular plasma membrane events measured in different cell lines can be compared. This article is part of a Special Issue entitled: Interactions between membrane receptors in cellular membranes edited by Kalina Hristova.
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Affiliation(s)
- Shuangru Huang
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore
| | - Shi Ying Lim
- NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore
| | - Anjali Gupta
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore
| | - Nirmalya Bag
- NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore.
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Veltman DM, Williams TD, Bloomfield G, Chen BC, Betzig E, Insall RH, Kay RR. A plasma membrane template for macropinocytic cups. eLife 2016; 5:e20085. [PMID: 27960076 PMCID: PMC5154761 DOI: 10.7554/elife.20085] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/14/2016] [Indexed: 12/18/2022] Open
Abstract
Macropinocytosis is a fundamental mechanism that allows cells to take up extracellular liquid into large vesicles. It critically depends on the formation of a ring of protrusive actin beneath the plasma membrane, which develops into the macropinocytic cup. We show that macropinocytic cups in Dictyostelium are organised around coincident intense patches of PIP3, active Ras and active Rac. These signalling patches are invariably associated with a ring of active SCAR/WAVE at their periphery, as are all examined structures based on PIP3 patches, including phagocytic cups and basal waves. Patch formation does not depend on the enclosing F-actin ring, and patches become enlarged when the RasGAP NF1 is mutated, showing that Ras plays an instructive role. New macropinocytic cups predominantly form by splitting from existing ones. We propose that cup-shaped plasma membrane structures form from self-organizing patches of active Ras/PIP3, which recruit a ring of actin nucleators to their periphery.
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Affiliation(s)
- Douwe M Veltman
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | | | | | - Bi-Chang Chen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Eric Betzig
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Robert H Insall
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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Bernardino de la Serna J, Schütz GJ, Eggeling C, Cebecauer M. There Is No Simple Model of the Plasma Membrane Organization. Front Cell Dev Biol 2016; 4:106. [PMID: 27747212 PMCID: PMC5040727 DOI: 10.3389/fcell.2016.00106] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/14/2016] [Indexed: 12/29/2022] Open
Abstract
Ever since technologies enabled the characterization of eukaryotic plasma membranes, heterogeneities in the distributions of its constituents were observed. Over the years this led to the proposal of various models describing the plasma membrane organization such as lipid shells, picket-and-fences, lipid rafts, or protein islands, as addressed in numerous publications and reviews. Instead of emphasizing on one model we in this review give a brief overview over current models and highlight how current experimental work in one or the other way do not support the existence of a single overarching model. Instead, we highlight the vast variety of membrane properties and components, their influences and impacts. We believe that highlighting such controversial discoveries will stimulate unbiased research on plasma membrane organization and functionality, leading to a better understanding of this essential cellular structure.
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Affiliation(s)
- Jorge Bernardino de la Serna
- Science and Technology Facilities Council, Rutherford Appleton Laboratory, Central Laser Facility, Research Complex at Harwell Harwell, UK
| | - Gerhard J Schütz
- Institute of Applied Physics, Technische Universität Wien Wien, Austria
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford Headley Way, UK
| | - Marek Cebecauer
- Department of Biophysical Chemistry, J.Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences Prague, Czech Republic
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29
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Plasma Membrane Organization of Epidermal Growth Factor Receptor in Resting and Ligand-Bound States. Biophys J 2016; 109:1925-36. [PMID: 26536269 DOI: 10.1016/j.bpj.2015.09.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/24/2015] [Accepted: 09/08/2015] [Indexed: 12/21/2022] Open
Abstract
The spatial arrangement of the epidermal growth factor receptor (EGFR) on the cellular plasma membrane is one of the prime factors that control its downstream signaling pathways and related functions. However, the molecular organization, which spans the scale from nanometers to micrometer-size clusters, has not been resolved in detail, mainly due to a lack of techniques with the required spatiotemporal resolution. Therefore, we used imaging total internal reflection-fluorescence correlation spectroscopy to investigate EGFR dynamics on live CHO-K1 plasma membranes in resting and ligand-bound states. In combination with the fluorescence correlation spectroscopy diffusion law, this provides information on the subresolution organization of EGFR on cell membranes. We found that overall EGFR organization is sensitive to both cholesterol and the actin cytoskeleton. EGFR in the resting state is partly trapped in cholesterol-containing domains, whereas another fraction exhibits cholesterol independent trapping on the membrane. Disruption of the cytoskeleton leads to a broader range of EGFR diffusion coefficients and a reduction of hop diffusion. In the ligand-bound state we found a dose-dependent behavior. At 10 ng/mL EGF the EGFR is endocytosed and recycled to the membrane, whereas diffusion and organization do not change significantly. At 100 ng/mL EGF the EGFR forms clusters, which are subsequently internalized, whereas outside the clusters diffusivity increases and the organization of the receptor remains unchanged. After disruption of cholesterol-containing domains or actin cytoskeleton, EGF induces microscopic EGFR clusters on the membrane and endocytosis is inhibited.
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30
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Shirey CM, Ward KE, Stahelin RV. Investigation of the biophysical properties of a fluorescently modified ceramide-1-phosphate. Chem Phys Lipids 2016; 200:32-41. [PMID: 27318040 DOI: 10.1016/j.chemphyslip.2016.06.004] [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: 05/27/2016] [Accepted: 06/14/2016] [Indexed: 12/11/2022]
Abstract
Ceramide-1-phosphate (C1P) is an important signaling sphingolipid and a metabolite of ceramide. C1P contains an anionic phosphomonoester head group and has been shown to regulate physiological and pathophysiological processes such as cell proliferation, inflammation, apoptosis, phagocytosis, and macrophage chemotaxis. Despite this mechanistic information on its role in intra- and intercellular communication, little information is available on the biophysical properties of C1P in biological membranes and how it interacts with effector proteins. Fluorescently labeled lipids have been a useful tool to understand the membrane behavior properties of lipids such as phosphatidylserine, cholesterol, and some phosphoinositides. However, to the best of our knowledge, fluorescently labeled C1P hasn't been implemented to investigate its ability to serve as a mimetic of endogenous C1P in cells or untagged C1P in in vitro experiments. Cellular and in vitro assays demonstrate TopFluor-C1P harbors a fluorescent group that is fully buried in the hydrocarbon core and fluoresces across the spectrum of physiological pH values. Moreover, TopFluor-C1P didn't affect cellular toxicity at concentrations employed, was as effective as unlabeled C1P in recruiting an established protein effector to intracellular membranes, and its subcellular localization recapitulated what is known for endogenous C1P. Notably, the diffusion coefficient of TopFluor-C1P was slower than that of TopFluor-phosphatidylserine or TopFluor-cholesterol in the plasma membrane and similar to that of other fluorescently labeled sphingolipids including ceramide and sphingomyelin. These studies demonstrate that TopFluor-C1P should be a reliable mimetic of C1P to study C1P membrane biophysical properties and C1P interactions with proteins.
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Affiliation(s)
- Carolyn M Shirey
- Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Katherine E Ward
- Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Robert V Stahelin
- Department of Chemistry and Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617, United States.
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Abstract
Polarized growth is critical for the development and maintenance of diverse organisms and tissues but particularly so in fungi, where nutrient uptake, communication, and reproduction all rely on cell asymmetries. To achieve polarized growth, fungi spatially organize both their cytosol and cortical membranes. Septins, a family of GTP-binding proteins, are key regulators of spatial compartmentalization in fungi and other eukaryotes. Septins form higher-order structures on fungal plasma membranes and are thought to contribute to the generation of cell asymmetries by acting as molecular scaffolds and forming diffusional barriers. Here we discuss the links between septins and polarized growth and consider molecular models for how septins contribute to cellular asymmetry in fungi.
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Affiliation(s)
- Anum Khan
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755;
| | - Molly McQuilken
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755;
| | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755;
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32
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Freeman SA, Goyette J, Furuya W, Woods EC, Bertozzi CR, Bergmeier W, Hinz B, van der Merwe PA, Das R, Grinstein S. Integrins Form an Expanding Diffusional Barrier that Coordinates Phagocytosis. Cell 2016; 164:128-140. [PMID: 26771488 DOI: 10.1016/j.cell.2015.11.048] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 09/07/2015] [Accepted: 11/14/2015] [Indexed: 01/12/2023]
Abstract
Phagocytosis is initiated by lateral clustering of receptors, which in turn activates Src-family kinases (SFKs). Activation of SFKs requires depletion of tyrosine phosphatases from the area of particle engagement. We investigated how the major phosphatase CD45 is excluded from contact sites, using single-molecule tracking. The mobility of CD45 increased markedly upon engagement of Fcγ receptors. While individual CD45 molecules moved randomly, they were displaced from the advancing phagocytic cup by an expanding diffusional barrier. By micropatterning IgG, the ligand of Fcγ receptors, we found that the barrier extended well beyond the perimeter of the receptor-ligand engagement zone. Second messengers generated by Fcγ receptors activated integrins, which formed an actin-tethered diffusion barrier that excluded CD45. The expanding integrin wave facilitates the zippering of Fcγ receptors onto the target and integrates the information from sparse receptor-ligand complexes, coordinating the progression and ultimate closure of the phagocytic cup.
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Affiliation(s)
- Spencer A Freeman
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Jesse Goyette
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Wendy Furuya
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Elliot C Woods
- Department of Chemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305-4401, USA
| | - Carolyn R Bertozzi
- Department of Chemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305-4401, USA
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, University of North Carolina, 120 Mason Farm Road, Chapel Hill, NC 27599-7260, USA
| | - Boris Hinz
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada
| | | | - Raibatak Das
- Department of Integrative Biology, University of Colorado, Denver, CO 80217-3364, USA
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Keenan Research Centre, St. Michael's Hospital, Toronto, ON M5S 1T8, Canada.
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33
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Naguib A. Following the trail of lipids: Signals initiated by PI3K function at multiple cellular membranes. Sci Signal 2016; 9:re4. [DOI: 10.1126/scisignal.aad7885] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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34
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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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35
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Ji C, Zhang Y, Xu P, Xu T, Lou X. Nanoscale Landscape of Phosphoinositides Revealed by Specific Pleckstrin Homology (PH) Domains Using Single-molecule Superresolution Imaging in the Plasma Membrane. J Biol Chem 2015; 290:26978-26993. [PMID: 26396197 DOI: 10.1074/jbc.m115.663013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 11/06/2022] Open
Abstract
Both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) are independent plasma membrane (PM) determinant lipids that are essential for multiple cellular functions. However, their nanoscale spatial organization in the PM remains elusive. Using single-molecule superresolution microscopy and new photoactivatable fluorescence probes on the basis of pleckstrin homology domains that specifically recognize phosphatidylinositides in insulin-secreting INS-1 cells, we report that the PI(4,5)P2 probes exhibited a remarkably uniform distribution in the major regions of the PM, with some sparse PI(4,5)P2-enriched membrane patches/domains of diverse sizes (383 ± 14 nm on average). Quantitative analysis revealed a modest concentration gradient that was much less steep than previously thought, and no densely packed PI(4,5)P2 nanodomains were observed. Live-cell superresolution imaging further demonstrated the dynamic structural changes of those domains in the flat PM and membrane protrusions. PI4P and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) showed similar spatial distributions as PI(4,5)P2. These data reveal the nanoscale landscape of key inositol phospholipids in the native PM and imply a framework for local cellular signaling and lipid-protein interactions at a nanometer scale.
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Affiliation(s)
- Chen Ji
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and
| | - Yongdeng Zhang
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tao Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuelin Lou
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and.
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36
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The cytoskeleton in cell-autonomous immunity: structural determinants of host defence. Nat Rev Immunol 2015; 15:559-73. [PMID: 26292640 DOI: 10.1038/nri3877] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Host cells use antimicrobial proteins, pathogen-restrictive compartmentalization and cell death in their defence against intracellular pathogens. Recent work has revealed that four components of the cytoskeleton--actin, microtubules, intermediate filaments and septins, which are well known for their roles in cell division, shape and movement--have important functions in innate immunity and cellular self-defence. Investigations using cellular and animal models have shown that these cytoskeletal proteins are crucial for sensing bacteria and for mobilizing effector mechanisms to eliminate them. In this Review, we highlight the emerging roles of the cytoskeleton as a structural determinant of cell-autonomous host defence.
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37
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Trimble WS, Grinstein S. Barriers to the free diffusion of proteins and lipids in the plasma membrane. ACTA ACUST UNITED AC 2015; 208:259-71. [PMID: 25646084 PMCID: PMC4315255 DOI: 10.1083/jcb.201410071] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Biological membranes segregate into specialized functional domains of distinct composition, which can persist for the entire life of the cell. How separation of their lipid and (glyco)protein components is generated and maintained is not well understood, but the existence of diffusional barriers has been proposed. Remarkably, the physical nature of such barriers and the manner whereby they impede the free diffusion of molecules in the plane of the membrane has rarely been studied in depth. Moreover, alternative mechanisms capable of generating membrane inhomogeneity are often disregarded. Here we describe prototypical biological systems where membrane segregation has been amply documented and discuss the role of diffusional barriers and other processes in the generation and maintenance of their structural and functional compartmentalization.
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Affiliation(s)
- William S Trimble
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Sergio Grinstein
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario M5C 1N8, Canada
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38
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Abstract
Our long-term efforts to elucidate receptor-mediated signalling in immune cells, particularly transmembrane signalling initiated by FcɛRI, the receptor for IgE in mast cells, led us unavoidably to contemplate the role of the heterogeneous plasma membrane. Our early investigations with fluorescence microscopy revealed co-redistribution of certain lipids and signalling components with antigen-cross-linked IgE-FcɛRI and pointed to participation of ordered membrane domains in the signalling process. With a focus on this function, we have worked along with others to develop diverse and increasingly sophisticated tools to analyse the complexity of membrane structure that facilitates regulation and targeting of signalling events. The present chapter describes how initial membrane interactions of clustered IgE-FcɛRI lead to downstream cellular responses and how biochemical information integrated with nanoscale resolution spectroscopy and imaging is providing mechanistic insights at the level of molecular complexes.
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Affiliation(s)
- David Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, U.S.A
| | - Barbara Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, U.S.A
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39
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Lee KI, Im W, Pastor RW. Langevin dynamics simulations of charged model phosphatidylinositol lipids in the presence of diffusion barriers: toward an atomic level understanding of corralling of PIP2 by protein fences in biological membranes. BMC BIOPHYSICS 2014; 7:13. [PMID: 25774289 PMCID: PMC4358915 DOI: 10.1186/s13628-014-0013-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 11/04/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND The polyvalent acidic lipid phosphatidylinositol, 4,5-bisphosphate (PIP2) is important for many cellular functions. It has been suggested that different pools of PIP2 exist in the cytoplasmic leaflet of the plasma membrane, and that such pooling could play a role in the regulation of PIP2. The mechanism of fencing, however, is not understood. RESULTS This study presents the results of Langevin dynamics simulations of PIP2 to elucidate some of the molecular level considerations that must be applied to models for fencing. For each simulation, a pool of PIP2 (modeled as charged spheres) was placed in containments with boundaries modeled as a single row of rods (steric or electrostatic) or rigid protein filaments. It is shown that even a small gap (20 Å, which is 1.85 times larger than the diameter of a PIP2 sphere) leads to poor steric blocking, and that electrostatic blockage is only effective at very high charge density. Filaments of human septin, yeast septin, and actin also failed to provide adequate blockage when placed on the membrane surface. The two septins do provide high blockage consistent with experiment and with phenomenological considerations of permeability when they are buried 9 Å and 12 Å below the membrane surface, respectively. In contrast, burial does not improve blockage by the "arch-shaped" actin filaments. Free energy estimates using implicit membrane-solvent models indicate that burial of the septins to about 10 Å can be achieved without penetration of charged residues into the hydrophobic region of the membrane. CONCLUSIONS These results imply that a functioning fence assembled from protein filaments must either be buried well below the membrane surface, have more than a single row, or contain additional components that fill small gaps in the filaments.
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Affiliation(s)
- Kyu Il Lee
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, KS USA
| | - Wonpil Im
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, KS USA
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD USA
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40
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Levin R, Grinstein S, Schlam D. Phosphoinositides in phagocytosis and macropinocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:805-23. [PMID: 25238964 DOI: 10.1016/j.bbalip.2014.09.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/23/2014] [Accepted: 09/08/2014] [Indexed: 01/08/2023]
Abstract
Professional phagocytes provide immunoprotection and aid in the maintenance of tissue homeostasis. They perform these tasks by recognizing, engulfing and eliminating pathogens and endogenous cell debris. Here, we examine the paramount role played by phosphoinositides in phagocytosis and macropinocytosis, two major endocytic routes that mediate the uptake of particulate and fluid matter, respectively. We analyze accumulating literature describing the molecular mechanisms whereby phosphoinositides translate environmental cues into the complex, sophisticated responses that underlie the phagocytic and macropinocytic responses. In addition, we exemplify virulence strategies involving modulation of host cell phosphoinositide signaling that are employed by bacteria to undermine immunity. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Roni Levin
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada
| | - Sergio Grinstein
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada; Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria St., Toronto M5C1N8, Canada.
| | - Daniel Schlam
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada
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41
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Lachambre S, Chopard C, Beaumelle B. Preliminary characterisation of nanotubes connecting T-cells and their use by HIV-1. Biol Cell 2014; 106:394-404. [DOI: 10.1111/boc.201400037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 08/07/2014] [Indexed: 01/06/2023]
Affiliation(s)
- Simon Lachambre
- CPBS, UMR 5236 CNRS-Université de Montpellier; Route de Mende; Montpellier 34293 France
| | - Christophe Chopard
- CPBS, UMR 5236 CNRS-Université de Montpellier; Route de Mende; Montpellier 34293 France
| | - Bruno Beaumelle
- CPBS, UMR 5236 CNRS-Université de Montpellier; Route de Mende; Montpellier 34293 France
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Swanson JA. Phosphoinositides and engulfment. Cell Microbiol 2014; 16:1473-83. [PMID: 25073505 DOI: 10.1111/cmi.12334] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 07/17/2014] [Accepted: 07/28/2014] [Indexed: 12/24/2022]
Abstract
Cellular engulfment of particles, cells or solutes displaces large domains of plasma membrane into intracellular membranous vacuoles. This transfer of membrane is accompanied by major transitions of the phosphoinositide (PI) species that comprise the cytoplasmic face of membrane bilayers. Mapping of membrane PIs during engulfment reveals distinct patterns of protein and PI distributions associated with each stage of engulfment, which correspond with activities that regulate the actin cytoskeleton, membrane movements and vesicle secretion. Experimental manipulation of PI chemistry during engulfment indicates that PIs integrate organelle identity and orient signal transduction cascades within confined subdomains of membrane. These pathways are exploited by microbial pathogens to direct or redirect the engulfment process.
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Affiliation(s)
- Joel A Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109-5620, USA
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Golgi and plasma membrane pools of PI(4)P contribute to plasma membrane PI(4,5)P2 and maintenance of KCNQ2/3 ion channel current. Proc Natl Acad Sci U S A 2014; 111:E2281-90. [PMID: 24843134 DOI: 10.1073/pnas.1407133111] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Plasma membrane (PM) phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] regulates the activity of many ion channels and other membrane-associated proteins. To determine precursor sources of the PM PI(4,5)P2 pool in tsA-201 cells, we monitored KCNQ2/3 channel currents and translocation of PHPLCδ1 domains as real-time indicators of PM PI(4,5)P2, and translocation of PHOSH2×2, and PHOSH1 domains as indicators of PM and Golgi phosphatidylinositol 4-phosphate [PI(4)P], respectively. We selectively depleted PI(4)P pools at the PM, Golgi, or both using the rapamycin-recruitable lipid 4-phosphatases. Depleting PI(4)P at the PM with a recruitable 4-phosphatase (Sac1) results in a decrease of PI(4,5)P2 measured by electrical or optical indicators. Depleting PI(4)P at the Golgi with the 4-phosphatase or disrupting membrane-transporting motors induces a decline in PM PI(4,5)P2. Depleting PI(4)P simultaneously at both the Golgi and the PM induces a larger decrease of PI(4,5)P2. The decline of PI(4,5)P2 following 4-phosphatase recruitment takes 1-2 min. Recruiting the endoplasmic reticulum (ER) toward the Golgi membranes mimics the effects of depleting PI(4)P at the Golgi, apparently due to the trans actions of endogenous ER Sac1. Thus, maintenance of the PM pool of PI(4,5)P2 appears to depend on precursor pools of PI(4)P both in the PM and in the Golgi. The decrease in PM PI(4,5)P2 when Sac1 is recruited to the Golgi suggests that the Golgi contribution is ongoing and that PI(4,5)P2 production may be coupled to important cell biological processes such as membrane trafficking or lipid transfer activity.
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Pham T, DiCiccio JE, Trimble WS. Cytoskeleton: septins do the horizontal tango. Curr Biol 2014; 24:R324-7. [PMID: 24735857 DOI: 10.1016/j.cub.2014.02.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Septins are a family of membrane-associated filamentous proteins that are essential in many biological processes, such as cell division. A recent study has provided the first visualization of septin filament formation in real time, leading to important new insights into their organization.
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Affiliation(s)
- Theodore Pham
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Jessica E DiCiccio
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - William S Trimble
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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Wu EL, Qi Y, Song KC, Klauda JB, Im W. Preferred orientations of phosphoinositides in bilayers and their implications in protein recognition mechanisms. J Phys Chem B 2014; 118:4315-25. [PMID: 24689790 DOI: 10.1021/jp500610t] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Phosphoinositides (PIPs), phosphorylated derivatives of phosphatidylinositol (PI), are essential regulatory lipids involved in various cellular processes, including signal transduction, membrane trafficking, and cytoskeletal remodeling. To gain insight into the protein-PIPs recognition process, it is necessary to study the inositol ring orientation (with respect to the membrane) of PIPs with different phosphorylation states. In this study, 8 PIPs (3 PIP, 2 PIP2, and 3 PIP3) with different phosphorylation and protonation sites have been separately simulated in two mixed bilayers (one with 20% phosphatidylserine (PS) lipids and another with PS lipids switched to phosphatidylcholine (PC) lipids), which roughly correspond to yeast membranes. Uniformity of the bilayer properties including hydrophobic thickness, acyl chain order parameters, and heavy atom density profiles is observed in both PS-contained and PC-enriched membranes due to the same hydrophobic core composition. The relationship between the inositol ring orientation (tilt and rotation angles) and its solvent-accessible surface area indicates that the orientation is mainly determined by its solvation energy. Different PIPs exhibit a clear preference in the inositol ring rotation angle. Surprisingly, a larger proportion of PIPs inositol rings stay closer to the surface of PS-contained membranes compared to PC-enriched ones. Such a difference is rationalized with the formation of more hydrogen bonds between the PS/PI headgroups and the PIPs inositol rings in PS-contained membranes. This hydrogen bond network could be functionally important; thus, the present results can potentially add important and detailed features into the existing protein-PIPs recognition mechanism.
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Affiliation(s)
- Emilia L Wu
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas , Lawrence, Kansas 66047, United States
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Prashar A, Bhatia S, Gigliozzi D, Martin T, Duncan C, Guyard C, Terebiznik MR. Filamentous morphology of bacteria delays the timing of phagosome morphogenesis in macrophages. ACTA ACUST UNITED AC 2014; 203:1081-97. [PMID: 24368810 PMCID: PMC3871431 DOI: 10.1083/jcb.201304095] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Uptake of bacterial filaments by macrophages is characterized by a prolonged phagocytic cup stage and diminished microbicidal activity during phagosome maturation. Although filamentous morphology in bacteria has been associated with resistance to phagocytosis, our understanding of the cellular mechanisms behind this process is limited. To investigate this, we followed the phagocytosis of both viable and dead Legionella pneumophila filaments. The engulfment of these targets occurred gradually and along the longitudinal axis of the filament, therefore defining a long-lasting phagocytic cup stage that determined the outcome of phagocytosis. We found that these phagocytic cups fused with endosomes and lysosomes, events linked to the maturation of phagosomes according to the canonical pathway, and not with the remodeling of phagocytic cups. Nevertheless, despite acquiring phagolysosomal features these phagocytic cups failed to develop hydrolytic capacity before their sealing. This phenomenon hampered the microbicidal activity of the macrophage and enhanced the capacity of viable filamentous L. pneumophila to escape phagosomal killing in a length-dependent manner. Our results demonstrate that key aspects in phagocytic cup remodeling and phagosomal maturation could be influenced by target morphology.
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Affiliation(s)
- Akriti Prashar
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
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Abstract
Macrophages ingest and kill microbes by phagocytosis and delivery to lysosomes. In this issue, Prashar et al. (2013, J. Cell Biol.http://dx.doi.org/10.1083/jcb.201304095) demonstrate that the elongated morphology of filamentous bacteria does not prevent ingestion by macrophages or the fusion of lysosomes, but creates a chimeric, unclosed phagolysosomal compartment whose leakiness blunts the toxicity of lysosomal enzymes, thereby increasing bacterial survival.
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Affiliation(s)
- Joel A Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109
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Jiang Z, Redfern RE, Isler Y, Ross AH, Gericke A. Cholesterol stabilizes fluid phosphoinositide domains. Chem Phys Lipids 2014; 182:52-61. [PMID: 24556334 DOI: 10.1016/j.chemphyslip.2014.02.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 02/06/2014] [Accepted: 02/07/2014] [Indexed: 11/19/2022]
Abstract
Local accumulation of phosphoinositides (PIPs) is an important factor for a broad range of cellular events including membrane trafficking and cell signaling. The negatively charged phosphoinositide headgroups can interact with cations or cationic proteins and this electrostatic interaction has been identified as the main phosphoinositide clustering mechanism. However, an increasing number of reports show that phosphoinositide-mediated signaling events are at least in some cases cholesterol dependent, suggesting other possible contributors to the segregation of phosphoinositides. Using fluorescence microscopy on giant unilamellar vesicles and monolayers at the air/water interface, we present data showing that cholesterol stabilizes fluid phosphoinositide-enriched phases. The interaction with cholesterol is observed for all investigated phosphoinositides (PI(4)P, PI(3,4)P2, PI(3,5)P2, PI(4,5)P2 and PI(3,4,5)P3) as well as phosphatidylinositol. We find that cholesterol is present in the phosphoinositide-enriched phase and that the resulting phase is fluid. Cholesterol derivatives modified at the hydroxyl group (cholestenone, cholesteryl ethyl ether) do not promote formation of phosphoinositide domains, suggesting an instrumental role of the cholesterol hydroxyl group in the observed cholesterol/phosphoinositide interaction. This leads to the hypothesis that cholesterol participates in an intermolecular hydrogen bond network formed among the phosphoinositide lipids. We had previously reported that the intra- and intermolecular hydrogen bond network between the phosphoinositide lipids leads to a reduction of the charge density at the phosphoinositide phosphomonoester groups (Kooijman et al., 2009). We believe that cholesterol acts as a spacer between the phosphoinositide lipids, thereby reducing the electrostatic repulsion, while participating in the hydrogen bond network, leading to its further stabilization. To illustrate the effect of phosphoinositide segregation on protein binding, we show that binding of the tumor suppressor protein PTEN to PI(5)P and PI(4,5)P2 is enhanced in the presence of cholesterol. These results provide new insights into how phosphoinositides mediate important cellular events.
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Affiliation(s)
- Zhiping Jiang
- Laboratory of Molecular Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Roberta E Redfern
- ProMedica Research Department, ProMedica Health System, Toledo, OH 43606, United States
| | - Yasmin Isler
- Academic Health Center BioRepository, ProMedica Health System, Toledo, OH 43606, United States
| | - Alonzo H Ross
- University of Massachusetts Medical School, Worcester, MA 01605, United States
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, United States.
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49
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Counterion-mediated cluster formation by polyphosphoinositides. Chem Phys Lipids 2014; 182:38-51. [PMID: 24440472 DOI: 10.1016/j.chemphyslip.2014.01.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/11/2013] [Accepted: 01/06/2014] [Indexed: 02/06/2023]
Abstract
Polyphosphoinositides (PPI) and in particular PI(4,5)P2, are among the most highly charged molecules in cell membranes, are important in many cellular signaling pathways, and are frequently targeted by peripheral polybasic proteins for anchoring through electrostatic interactions. Such interactions between PIP2 and proteins containing polybasic stretches depend on the physical state and the lateral distribution of PIP2 within the inner leaflet of the cell's lipid bilayer. The physical and chemical properties of PIP2 such as pH-dependent changes in headgroup ionization and area per molecule as determined by experiments together with molecular simulations that predict headgroup conformations at various ionization states have revealed the electrostatic properties and phase behavior of PIP2-containing membranes. This review focuses on recent experimental and computational developments in defining the physical chemistry of PIP2 and its interactions with counterions. Ca(2+)-induced changes in PIP2 charge, conformation, and lateral structure within the membrane are documented by numerous experimental and computational studies. A simplified electrostatic model successfully predicts the Ca(2+)-driven formation of PIP2 clusters but cannot account for the different effects of Ca(2+) and Mg(2+) on PIP2-containing membranes. A more recent computational study is able to see the difference between Ca(2+) and Mg(2+) binding to PIP2 in the absence of a membrane and without cluster formation. Spectroscopic studies suggest that divalent cation- and multivalent polyamine-induced changes in the PIP2 lateral distribution in model membrane are also different, and not simply related to the net charge of the counterion. Among these differences is the capacity of Ca(2+) but not other polycations to induce nm scale clusters of PIP2 in fluid membranes. Recent super resolution optical studies show that PIP2 forms nanoclusters in the inner leaflet of a plasma membrane with a similar size distribution as those induced by Ca(2+) in model membranes. The mechanisms by which PIP2 forms nanoclusters and other structures inside a cell remain to be determined, but the unique electrostatic properties of PIP2 and its interactions with multivalent counterions might have particular physiological relevance.
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50
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Hille B, Dickson E, Kruse M, Falkenburger B. Dynamic metabolic control of an ion channel. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 123:219-47. [PMID: 24560147 DOI: 10.1016/b978-0-12-397897-4.00008-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
G-protein-coupled receptors mediate responses to external stimuli in various cell types. We are interested in the modulation of KCNQ2/3 potassium channels by the Gq-coupled M1 muscarinic (acetylcholine) receptor (M1R). Here, we describe development of a mathematical model that incorporates all known steps along the M1R signaling cascade and accurately reproduces the macroscopic behavior we observe when KCNQ2/3 currents are inhibited following M1R activation. Gq protein-coupled receptors of the plasma membrane activate phospholipase C (PLC) which cleaves the minor plasma membrane lipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) into the second messengers diacylgycerol and inositol 1,4,5-trisphosphate, leading to calcium release, protein kinase C (PKC) activation, and PI(4,5)P2 depletion. Combining optical and electrical techniques with knowledge of relative abundance of each signaling component has allowed us to develop a kinetic model and determine that (i) M1R activation and M1R/Gβ interaction are fast; (ii) Gαq/Gβ separation and Gαq/PLC interaction have intermediate time constants; (iii) the amount of activated PLC limits the rate of KCNQ2/3 suppression; (iv) weak PLC activation can elicit robust calcium signals without net PI(4,5)P2 depletion or KCNQ2/3 channel inhibition; and (v) depletion of PI(4,5)P2, and not calcium/CaM or PKC-mediated phosphorylation, closes KCNQ2/3 potassium channels, thereby increasing neuronal excitability.
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Affiliation(s)
- Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - Eamonn Dickson
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - Martin Kruse
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
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