101
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Duncan AL, Reddy T, Koldsø H, Hélie J, Fowler PW, Chavent M, Sansom MSP. Protein crowding and lipid complexity influence the nanoscale dynamic organization of ion channels in cell membranes. Sci Rep 2017; 7:16647. [PMID: 29192147 PMCID: PMC5709381 DOI: 10.1038/s41598-017-16865-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/15/2017] [Indexed: 01/07/2023] Open
Abstract
Cell membranes are crowded and complex environments. To investigate the effect of protein-lipid interactions on dynamic organization in mammalian cell membranes, we have performed coarse-grained molecular dynamics simulations containing >100 copies of an inwardly rectifying potassium (Kir) channel which forms specific interactions with the regulatory lipid phosphatidylinositol 4,5-bisphosphate (PIP2). The tendency of protein molecules to cluster has the effect of organizing the membrane into dynamic compartments. At the same time, the diversity of lipids present has a marked effect on the clustering behavior of ion channels. Sub-diffusion of proteins and lipids is observed. Protein crowding alters the sub-diffusive behavior of proteins and lipids such as PIP2 which interact tightly with Kir channels. Protein crowding also affects bilayer properties, such as membrane undulations and bending rigidity, in a PIP2-dependent manner. This interplay between the diffusion and the dynamic organization of Kir channels may have important implications for channel function.
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Affiliation(s)
- Anna L Duncan
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Tyler Reddy
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- T-6, MS K710, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- D. E. Shaw Research, 120 W 45th St., New York, NY, 10036, USA
| | - Jean Hélie
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Semmle, Blue Boar Court, 9 Alfred St, Oxford, OX1 4EH, UK
| | - Philip W Fowler
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Matthieu Chavent
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- IPBS-CNRS, Toulouse, Midi-Pyrénées, France
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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102
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Ramírez-Anguita JM, Rodríguez-Espigares I, Guixà-González R, Bruno A, Torrens-Fontanals M, Varela-Rial A, Selent J. Membrane cholesterol effect on the 5-HT 2A receptor: Insights into the lipid-induced modulation of an antipsychotic drug target. Biotechnol Appl Biochem 2017; 65:29-37. [PMID: 28877377 DOI: 10.1002/bab.1608] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The serotonin 5-hydroxytryptamine 2A (5-HT2A ) receptor is a G-protein-coupled receptor (GPCR) relevant for the treatment of CNS disorders. In this regard, neuronal membrane composition in the brain plays a crucial role in the modulation of the receptor functioning. Since cholesterol is an essential component of neuronal membranes, we have studied its effect on the 5-HT2A receptor dynamics through all-atom MD simulations. We find that the presence of cholesterol in the membrane increases receptor conformational variability in most receptor segments. Importantly, detailed structural analysis indicates that conformational variability goes along with the destabilization of hydrogen bonding networks not only within the receptor but also between receptor and lipids. In addition to increased conformational variability, we also find receptor segments with reduced variability. Our analysis suggests that this increased stabilization is the result of stabilizing effects of tightly bound cholesterol molecules to the receptor surface. Our finding contributes to a better understanding of membrane-induced alterations of receptor dynamics and points to cholesterol-induced stabilizing and destabilizing effects on the conformational variability of GPCRs.
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Affiliation(s)
- Juan Manuel Ramírez-Anguita
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Ismael Rodríguez-Espigares
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Ramon Guixà-González
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain.,Institut für Medizinische Physik und Biophysik, Charité, Berlin, Germany
| | - Agostino Bruno
- Department of Pharmacy, Università degli studi di Parma, Italy, Parma
| | - Mariona Torrens-Fontanals
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Alejandro Varela-Rial
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
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103
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Desai AJ, Miller LJ. Changes in the plasma membrane in metabolic disease: impact of the membrane environment on G protein-coupled receptor structure and function. Br J Pharmacol 2017; 175:4009-4025. [PMID: 28691227 DOI: 10.1111/bph.13943] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/08/2017] [Accepted: 07/04/2017] [Indexed: 12/11/2022] Open
Abstract
Drug development targeting GPCRs often utilizes model heterologous cell expression systems, reflecting an implicit assumption that the membrane environment has little functional impact on these receptors or on their responsiveness to drugs. However, much recent data have illustrated that membrane components can have an important functional impact on intrinsic membrane proteins. This review is directed toward gaining a better understanding of the structure of the plasma membrane in health and disease, and how this organelle can influence GPCR structure, function and regulation. It is important to recognize that the membrane provides a potential mode of lateral allosteric regulation of GPCRs and can affect the effectiveness of drugs and their biological responses in various disease states, which can even vary among individuals across the population. The type 1 cholecystokinin receptor is reviewed as an exemplar of a class A GPCR that is affected in this way by changes in the plasma membrane. LINKED ARTICLES This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.
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Affiliation(s)
- Aditya J Desai
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA
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104
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Sviridov D, Mukhamedova N. Cholesterol: a dark horse in signalling race. Curr Opin Lipidol 2017; 28:385-386. [PMID: 28700381 DOI: 10.1097/mol.0000000000000435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Dmitri Sviridov
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
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105
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Kim JH, Singh A, Del Poeta M, Brown DA, London E. The effect of sterol structure upon clathrin-mediated and clathrin-independent endocytosis. J Cell Sci 2017; 130:2682-2695. [PMID: 28655854 DOI: 10.1242/jcs.201731] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 06/22/2017] [Indexed: 12/25/2022] Open
Abstract
Ordered lipid domains (rafts) in plasma membranes have been hypothesized to participate in endocytosis based on inhibition of endocytosis by removal or sequestration of cholesterol. To more carefully investigate the role of the sterol in endocytosis, we used a substitution strategy to replace cholesterol with sterols that show various raft-forming abilities and chemical structures. Both clathrin-mediated endocytosis of transferrin and clathrin-independent endocytosis of clustered placental alkaline phosphatase were measured. A subset of sterols reversibly inhibited both clathrin-dependent and clathrin-independent endocytosis. The ability of a sterol to support lipid raft formation was necessary for endocytosis. However, it was not sufficient, because a sterol lacking a 3β-OH group did not support endocytosis even though it had the ability to support ordered domain formation. Double bonds in the sterol rings and an aliphatic tail structure identical to that of cholesterol were neither necessary nor sufficient to support endocytosis. This study shows that substitution using a large number of sterols can define the role of sterol structure in cellular functions. Hypotheses for how sterol structure can similarly alter clathrin-dependent and clathrin-independent endocytosis are discussed.
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Affiliation(s)
- Ji Hyun Kim
- Dept. of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Ashutosh Singh
- Dept. of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Maurizio Del Poeta
- Dept. of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Deborah A Brown
- Dept. of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Erwin London
- Dept. of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
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106
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Javanainen M, Martinez-Seara H, Vattulainen I. Nanoscale Membrane Domain Formation Driven by Cholesterol. Sci Rep 2017; 7:1143. [PMID: 28442766 PMCID: PMC5430823 DOI: 10.1038/s41598-017-01247-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 03/27/2017] [Indexed: 11/09/2022] Open
Abstract
Biological membranes generate specific functions through compartmentalized regions such as cholesterol-enriched membrane nanodomains that host selected proteins. Despite the biological significance of nanodomains, details on their structure remain elusive. They cannot be observed via microscopic experimental techniques due to their small size, yet there is also a lack of atomistic simulation models able to describe spontaneous nanodomain formation in sufficiently simple but biologically relevant complex membranes. Here we use atomistic simulations to consider a binary mixture of saturated dipalmitoylphosphatidylcholine and cholesterol - the "minimal standard" for nanodomain formation. The simulations reveal how cholesterol drives the formation of fluid cholesterol-rich nanodomains hosting hexagonally packed cholesterol-poor lipid nanoclusters, both of which show registration between the membrane leaflets. The complex nanodomain substructure forms when cholesterol positions itself in the domain boundary region. Here cholesterol can also readily flip-flop across the membrane. Most importantly, replacing cholesterol with a sterol characterized by a less asymmetric ring region impairs the emergence of nanodomains. The model considered explains a plethora of controversial experimental results and provides an excellent basis for further computational studies on nanodomains. Furthermore, the results highlight the role of cholesterol as a key player in the modulation of nanodomains for membrane protein function.
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Affiliation(s)
- Matti Javanainen
- Laboratory of Physics, Tampere University of Technology, Tampere, Finland.,Department of Physics, University of Helsinki, Helsinki, Finland
| | - Hector Martinez-Seara
- Laboratory of Physics, Tampere University of Technology, Tampere, Finland. .,Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic.
| | - Ilpo Vattulainen
- Laboratory of Physics, Tampere University of Technology, Tampere, Finland. .,Department of Physics, University of Helsinki, Helsinki, Finland. .,MEMPHYS - Centre for Biomembrane Physics, University of Southern Denmark, Odense, Denmark.
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