1
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Chiu PL, Orjuela JD, de Groot BL, Aponte Santamaría C, Walz T. Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts. eLife 2024; 12:RP90851. [PMID: 39222068 PMCID: PMC11368405 DOI: 10.7554/elife.90851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
Aquaporin-0 (AQP0) tetramers form square arrays in lens membranes through a yet unknown mechanism, but lens membranes are enriched in sphingomyelin and cholesterol. Here, we determined electron crystallographic structures of AQP0 in sphingomyelin/cholesterol membranes and performed molecular dynamics (MD) simulations to establish that the observed cholesterol positions represent those seen around an isolated AQP0 tetramer and that the AQP0 tetramer largely defines the location and orientation of most of its associated cholesterol molecules. At a high concentration, cholesterol increases the hydrophobic thickness of the annular lipid shell around AQP0 tetramers, which may thus cluster to mitigate the resulting hydrophobic mismatch. Moreover, neighboring AQP0 tetramers sandwich a cholesterol deep in the center of the membrane. MD simulations show that the association of two AQP0 tetramers is necessary to maintain the deep cholesterol in its position and that the deep cholesterol increases the force required to laterally detach two AQP0 tetramers, not only due to protein-protein contacts but also due to increased lipid-protein complementarity. Since each tetramer interacts with four such 'glue' cholesterols, avidity effects may stabilize larger arrays. The principles proposed to drive AQP0 array formation could also underlie protein clustering in lipid rafts.
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Affiliation(s)
- Po-Lin Chiu
- Department of Cell Biology, Harvard Medical SchoolBostonUnited States
| | - Juan D Orjuela
- Max Planck Tandem Group in Computational Biophysics, Universidad de los AndesBogotáColombia
- Biomedical Engineering Department, Universidad de los AndesBogotáColombia
| | - Bert L de Groot
- Computational Biomolecular Dynamics Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Camilo Aponte Santamaría
- Max Planck Tandem Group in Computational Biophysics, Universidad de los AndesBogotáColombia
- Molecular Biomechanics Group, Heidelberg Institute for Theoretical StudiesHeidelbergGermany
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical SchoolBostonUnited States
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2
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Chahinian H, Yahi N, Fantini J. Glutamate, Gangliosides, and the Synapse: Electrostatics at Work in the Brain. Int J Mol Sci 2024; 25:8583. [PMID: 39201269 PMCID: PMC11354842 DOI: 10.3390/ijms25168583] [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: 07/18/2024] [Revised: 08/02/2024] [Accepted: 08/04/2024] [Indexed: 09/02/2024] Open
Abstract
The synapse is a piece of information transfer machinery replacing the electrical conduction of nerve impulses at the end of the neuron. Like many biological mechanisms, its functioning is heavily affected by time constraints. The solution selected by evolution is based on chemical communication that, in theory, cannot compete with the speed of nerve conduction. Nevertheless, biochemical and biophysical compensation mechanisms mitigate this intrinsic weakness: (i) through the high concentrations of neurotransmitters inside the synaptic vesicles; (ii) through the concentration of neurotransmitter receptors in lipid rafts, which are signaling platforms; indeed, the presence of raft lipids, such as gangliosides and cholesterol, allows a fine tuning of synaptic receptors by these lipids; (iii) through the negative electrical charges of the gangliosides, which generate an attractive (for cationic neurotransmitters, such as serotonin) or repulsive (for anionic neurotransmitters, such as glutamate) electric field. This electric field controls the flow of glutamate in the tripartite synapse involving pre- and post-synaptic neurons and the astrocyte. Changes in the expression of brain gangliosides can disrupt the functioning of the glutamatergic synapse, causing fatal diseases, such as Rett syndrome. In this review, we propose an in-depth analysis of the role of gangliosides in the glutamatergic synapse, highlighting the primordial and generally overlooked role played by the electric field of synaptic gangliosides.
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Affiliation(s)
| | | | - Jacques Fantini
- Faculty of Sciences, Department of Biology, University of Aix-Marseille, INSERM UA16, 13015 Marseille, France; (H.C.); (N.Y.)
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3
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Chiu PL, Orjuela JD, de Groot BL, Aponte-Santamaría C, Walz T. Structure and dynamics of cholesterol-mediated aquaporin-0 arrays and implications for lipid rafts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.16.540959. [PMID: 37292626 PMCID: PMC10245776 DOI: 10.1101/2023.05.16.540959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Aquaporin-0 (AQP0) tetramers form square arrays in lens membranes through a yet unknown mechanism, but lens membranes are enriched in sphingomyelin and cholesterol. Here, we determined electron crystallographic structures of AQP0 in sphingomyelin/cholesterol membranes and performed molecular dynamics (MD) simulations to establish that the observed cholesterol positions represent those seen around an isolated AQP0 tetramer and that the AQP0 tetramer largely defines the location and orientation of most of its associated cholesterol molecules. At a high concentration, cholesterol increases the hydrophobic thickness of the annular lipid shell around AQP0 tetramers, which may thus cluster to mitigate the resulting hydrophobic mismatch. Moreover, neighboring AQP0 tetramers sandwich a cholesterol deep in the center of the membrane. MD simulations show that the association of two AQP0 tetramers is necessary to maintain the deep cholesterol in its position and that the deep cholesterol increases the force required to laterally detach two AQP0 tetramers, not only due to protein-protein contacts but also due to increased lipid-protein complementarity. Since each tetramer interacts with four such 'glue' cholesterols, avidity effects may stabilize larger arrays. The principles proposed to drive AQP0 array formation could also underlie protein clustering in lipid rafts.
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4
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Lingwood C. Is cholesterol both the lock and key to abnormal transmembrane signals in Autism Spectrum Disorder? Lipids Health Dis 2024; 23:114. [PMID: 38643132 PMCID: PMC11032007 DOI: 10.1186/s12944-024-02075-3] [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: 12/12/2023] [Accepted: 03/08/2024] [Indexed: 04/22/2024] Open
Abstract
Disturbances in cholesterol homeostasis have been associated with ASD. Lipid rafts are central in many transmembrane signaling pathways (including mTOR) and changes in raft cholesterol content affect their order function. Cholesterol levels are controlled by several mechanisms, including endoplasmic reticulum associated degradation (ERAD) of the rate limiting HMGCoA reductase. A new approach to increase cholesterol via temporary ERAD blockade using a benign bacterial toxin-derived competitor for the ERAD translocon is suggested.A new lock and key model for cholesterol/lipid raft dependent signaling is proposed in which the rafts provide both the afferent and efferent 'tumblers' across the membrane to allow 'lock and key' receptor transmembrane signals.
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Affiliation(s)
- Clifford Lingwood
- Division of Molecular Medicine, Research Institute, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.
- Departments of Biochemistry and Laboratory Medicine & Pathobiology, University of Toronto, Ontario, M5S 1A8, Canada.
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5
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Naglekar A, Chattopadhyay A, Sengupta D. Palmitoylation of the Glucagon-like Peptide-1 Receptor Modulates Cholesterol Interactions at the Receptor-Lipid Microenvironment. J Phys Chem B 2023; 127:11000-11010. [PMID: 38111968 DOI: 10.1021/acs.jpcb.3c05930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
The G protein-coupled receptor (GPCR) superfamily of cell surface receptors has been shown to be functionally modulated by post-translational modifications. The glucagon-like peptide receptor-1 (GLP-1R), which is a drug target in diabetes and obesity, undergoes agonist-dependent palmitoyl tail conjugation. The palmitoylation in the C-terminal domain of GLP-1R has been suggested to modulate the receptor-lipid microenvironment. In this work, we have performed coarse-grain molecular dynamics simulations of palmitoylated and nonpalmitoylated GLP-1R to analyze the differential receptor-lipid interactions. Interestingly, the placement and dynamics of the C-terminal domain of GLP-1R are found to be directly dependent on the palmitoyl tail. We observe that both cholesterol and phospholipids interact with the receptor but display differential interactions in the presence and absence of the palmitoyl tail. We characterize important cholesterol-binding sites and validate sites that have been previously reported in experimentally resolved structures of the receptor. We show that the receptor acts like a conduit for cholesterol flip-flop by stabilizing cholesterol in the membrane core. Taken together, our work represents an important step in understanding the molecular effects of lipid modifications in GPCRs.
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Affiliation(s)
- Amit Naglekar
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Amitabha Chattopadhyay
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
| | - Durba Sengupta
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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6
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Girych M, Kulig W, Enkavi G, Vattulainen I. How Neuromembrane Lipids Modulate Membrane Proteins: Insights from G-Protein-Coupled Receptors (GPCRs) and Receptor Tyrosine Kinases (RTKs). Cold Spring Harb Perspect Biol 2023; 15:a041419. [PMID: 37487628 PMCID: PMC10547395 DOI: 10.1101/cshperspect.a041419] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Lipids play a diverse and critical role in cellular processes in all tissues. The unique lipid composition of nerve membranes is particularly interesting because it contains, among other things, polyunsaturated lipids, such as docosahexaenoic acid, which the body only gets through the diet. The crucial role of lipids in neurological processes, especially in receptor-mediated cell signaling, is emphasized by the fact that in many neuropathological diseases there are significant deviations in the lipid composition of nerve membranes compared to healthy individuals. The lipid composition of neuromembranes can significantly affect the function of receptors by regulating the physical properties of the membrane or by affecting specific interactions between receptors and lipids. In addition, it is worth noting that the ligand-binding pocket of many receptors is located inside the cell membrane, due to which lipids can even modulate the binding of ligands to their receptors. These mechanisms highlight the importance of lipids in the regulation of membrane receptor activation and function. In this article, we focus on two major protein families: G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) and discuss how lipids affect their function in neuronal membranes, elucidating the basic mechanisms underlying neuronal function and dysfunction.
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Affiliation(s)
- Mykhailo Girych
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Waldemar Kulig
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Giray Enkavi
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
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7
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Ray AP, Thakur N, Pour NG, Eddy MT. Dual mechanisms of cholesterol-GPCR interactions that depend on membrane phospholipid composition. Structure 2023; 31:836-847.e6. [PMID: 37236187 PMCID: PMC10330489 DOI: 10.1016/j.str.2023.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/25/2023] [Accepted: 05/01/2023] [Indexed: 05/28/2023]
Abstract
Cholesterol is a critical component of mammalian cell membranes and an allosteric modulator of G protein-coupled receptors (GPCRs), but divergent views exist on the mechanisms by which cholesterol influences receptor functions. Leveraging the benefits of lipid nanodiscs, i.e., quantitative control of lipid composition, we observe distinct impacts of cholesterol in the presence and absence of anionic phospholipids on the function-related conformational dynamics of the human A2A adenosine receptor (A2AAR). Direct receptor-cholesterol interactions drive activation of agonist-bound A2AAR in membranes containing zwitterionic phospholipids. Intriguingly, the presence of anionic lipids attenuates cholesterol's impact through direct interactions with the receptor, highlighting a more complex role for cholesterol that depends on membrane phospholipid composition. Targeted amino acid replacements at two frequently predicted cholesterol interaction sites showed distinct impacts of cholesterol at different receptor locations, demonstrating the ability to delineate different roles of cholesterol in modulating receptor signaling and maintaining receptor structural integrity.
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Affiliation(s)
- Arka Prabha Ray
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Naveen Thakur
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Niloofar Gopal Pour
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA
| | - Matthew T Eddy
- Department of Chemistry, University of Florida, 126 Sisler Hall, Gainesville, FL 32611, USA.
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8
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Isu UH, Badiee SA, Khodadadi E, Moradi M. Cholesterol in Class C GPCRs: Role, Relevance, and Localization. MEMBRANES 2023; 13:301. [PMID: 36984688 PMCID: PMC10056374 DOI: 10.3390/membranes13030301] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
G-protein coupled receptors (GPCRs), one of the largest superfamilies of cell-surface receptors, are heptahelical integral membrane proteins that play critical roles in virtually every organ system. G-protein-coupled receptors operate in membranes rich in cholesterol, with an imbalance in cholesterol level within the vicinity of GPCR transmembrane domains affecting the structure and/or function of many GPCRs, a phenomenon that has been linked to several diseases. These effects of cholesterol could result in indirect changes by altering the mechanical properties of the lipid environment or direct changes by binding to specific sites on the protein. There are a number of studies and reviews on how cholesterol modulates class A GPCRs; however, this area of study is yet to be explored for class C GPCRs, which are characterized by a large extracellular region and often form constitutive dimers. This review highlights specific sites of interaction, functions, and structural dynamics involved in the cholesterol recognition of the class C GPCRs. We summarize recent data from some typical family members to explain the effects of membrane cholesterol on the structural features and functions of class C GPCRs and speculate on their corresponding therapeutic potential.
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Affiliation(s)
| | | | | | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
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9
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Tzortzini E, Corey RA, Kolocouris A. Comparative Study of Receptor-, Receptor State-, and Membrane-Dependent Cholesterol Binding Sites in A 2A and A 1 Adenosine Receptors Using Coarse-Grained Molecular Dynamics Simulations. J Chem Inf Model 2023; 63:928-949. [PMID: 36637988 DOI: 10.1021/acs.jcim.2c01181] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We used coarse-grained molecular dynamics (CG MD) simulations to study protein-cholesterol interactions for different activation states of the A2A adenosine receptor (A2AR) and the A1 adenosine receptor (A1R) and predict new cholesterol binding sites indicating amino acid residues with a high residence time in three biologically relevant membranes. Compared to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)-cholesterol and POPC-phosphatidylinositol-bisphosphate (PIP2)-cholesterol, the plasma mimetic membrane best described the cholesterol binding sites previously detected for the inactive state of A2AR and revealed the binding sites with long-lasting amino acid residues. We observed that using the plasma mimetic membrane and plotting residues with cholesterol residence time ≥2 μs, our CG MD simulations captured most obviously the cholesterol-protein interactions. For the inactive A2AR, we identified one more binding site in which cholesterol is bound to residues with a long residence time compared to the previously detected, for the active A1R, three binding sites, and for the inactive A1R, two binding sites. We calculated that for the active states, cholesterol binds to residues with a much longer residence time compared to the inactive state for both A2AR and A1R. The stability of the identified binding sites to A1R or A2AR with CG MD simulations was additionally investigated with potential of mean force calculations using umbrella sampling. We observed that the binding sites with residues to which cholesterol has a long residence time in A2AR have shallow binding free energy minima compared to the related binding sites in A1R, suggesting a stronger binding for cholesterol to A1R. The differences in binding sites in which cholesterol is stabilized and interacts with residues with a long residence time between active and inactive states of A1R and A2AR can be important for differences in functional activity and orthosteric agonist or antagonist affinity and can be used for the design of allosteric modulators, which can bind through lipid pathways. We observed a stronger binding for cholesterol to A1R (i.e., generally higher association rates) compared to A2AR, which remains to be demonstrated. For the active states, cholesterol binds to residues with much longer residence times compared to the inactive state for both A2AR and A1R. Taken together, binding sites of active A1R may be considered as promising allosteric targets.
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Affiliation(s)
- Efpraxia Tzortzini
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, 15771Athens, Greece
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, OxfordOX1 3QU, United Kingdom
| | - Antonios Kolocouris
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, 15771Athens, Greece
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10
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Cornut D, Soulié M, Moreno A, Boussambe GNM, Damian M, Igonet S, Guillet P, Banères JL, Durand G. Non-ionic cholesterol-based additives for the stabilization of membrane proteins. Biochimie 2023; 205:27-39. [PMID: 36586567 DOI: 10.1016/j.biochi.2022.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/30/2022]
Abstract
We report herein the synthesis of two non-ionic amphiphiles with a cholesterol hydrophobic moiety that can be used as chemical additives for biochemical studies of membrane proteins. They were designed to show a high similarity with the planar steroid core of cholesterol and small-to-medium polar head groups attached at the C3 position of ring-A on the sterol skeleton. The two Chol-Tris and Chol-DG have a Tris-hydroxymethyl and a branched diglucose polar head group, respectively, which provide them sufficient water solubility when mixed with the "gold standard" detergent n-Dodecyl-β-D-Maltoside (DDM). The colloidal properties of these mixed micelles were investigated by means of surface tension (SFT) measurements and dynamic light scattering (DLS) experiments and showed the formation of globular micelles of about 8 nm in diameter with a critical micellar concentration of 0.20 mM for DDM:Chol-DG and 0.22 mM for DDM:Chol-Tris. We showed that mixed micelles do not alter the extraction potency of a G-protein coupled receptor (GPCR): the human adenosine A2A receptor (A2AR). The thermostabilizing effect of the mixed micelles was confirmed on two GPCRs, A2AR and the growth hormone secretagogue receptor (GHSR). Finally, these two mixed micelles were found suitable for the purification of an active form of A2AR which remained able to bind two ligands of different class i.e. the specific agonist CGS-21680 and the specific inverse agonist ZM-241385. This suggests that Chol-Tris and Chol-DG may be used as a non-ionic alternative to the cholesteryl hemisuccinate (CHS) stabilizing agent.
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Affiliation(s)
- Damien Cornut
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM & Avignon Université, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France; CHEM2STAB, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France
| | - Marine Soulié
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM & Avignon Université, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France; CHEM2STAB, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France
| | | | - Gildas Nyame Mendendy Boussambe
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM & Avignon Université, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France; CHEM2STAB, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France
| | - Marjorie Damian
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM, 1919 route de Mende, 34293, Montpellier, Cedex 5, France
| | | | - Pierre Guillet
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM & Avignon Université, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France; CHEM2STAB, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France
| | - Jean-Louis Banères
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM, 1919 route de Mende, 34293, Montpellier, Cedex 5, France
| | - Grégory Durand
- Institut des Biomolécules Max Mousseron UMR 5247 UM-CNRS-ENSCM & Avignon Université, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France; CHEM2STAB, 301 rue Baruch de Spinoza, 84916, Avignon, Cedex 9, France.
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11
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Kumar A, Sarkar P, Chattopadhyay A. Metabolic depletion of sphingolipids inhibits agonist-induced endocytosis of the serotonin 1A receptor. Traffic 2023; 24:95-107. [PMID: 36533718 DOI: 10.1111/tra.12879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 10/11/2022] [Accepted: 10/18/2022] [Indexed: 12/23/2022]
Abstract
G protein-coupled receptors (GPCRs) are vital cellular signaling machinery and currently represent ~40% drug targets. Endocytosis of GPCRs is an important process that allows stringent spatiotemporal control over receptor population on the cell surface. Although the role of proteins in GPCR endocytosis is well addressed, the contribution of membrane lipids in this process is rather unexplored. Sphingolipids are essential functional lipids in higher eukaryotes and are implicated in several neurological functions. To understand the role of sphingolipids in GPCR endocytosis, we subjected cells expressing human serotonin1A receptors (an important neurotransmitter GPCR involved in cognitive and behavioral functions) to metabolic sphingolipid depletion using fumonisin B1 , an inhibitor of sphingolipid biosynthetic pathway. Our results, using flow cytometric analysis and confocal microscopic imaging, show that sphingolipid depletion inhibits agonist-induced endocytosis of the serotonin1A receptor in a concentration-dependent manner, which was restored when sphingolipid levels were replenished. We further show that there was no change in the internalization of transferrin, a marker for clathrin-mediated endocytosis, under sphingolipid-depleted condition, highlighting the specific requirement of sphingolipids for endocytosis of serotonin1A receptors. Our results reveal the regulatory role of sphingolipids in GPCR endocytosis and highlight the importance of neurotransmitter receptor trafficking in health and disease.
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Affiliation(s)
- Abhishek Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Amity Institute of Biotechnology, Amity University Haryana, Gurugram, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
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12
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Mohole M, Sengupta D, Chattopadhyay A. Synergistic and Competitive Lipid Interactions in the Serotonin 1A Receptor Microenvironment. ACS Chem Neurosci 2022; 13:3403-3415. [PMID: 36351047 DOI: 10.1021/acschemneuro.2c00422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The interaction of lipids with G-protein-coupled receptors (GPCRs) has been shown to modulate and dictate several aspects of GPCR organization and function. Diverse lipid interaction sites have been identified from structural biology, bioinformatics, and molecular dynamics studies. For example, multiple cholesterol interaction sites have been identified in the serotonin1A receptor, along with distinct and overlapping sphingolipid interaction sites. How these lipids interact with each other and what is the resultant effect on the receptor is still not clear. In this work, we have analyzed lipid-lipid crosstalk at the receptor of the serotonin1A receptor embedded in a membrane bilayer that mimics the neuronal membrane composition by long coarse-grain simulations. Using a set of similarity coefficients, we classified lipids that bind at the receptor together as synergistic cobinding, and those that bind individually as competitive. Our results show that certain lipids interact with the serotonin1A receptor in synergy with each other. Not surprisingly, the ganglioside GM1 and cholesterol show a synergistic cobinding, along with the relatively uncommon GM1-phosphatidylethanolamine (PE) and cholesterol-PE synergy. In contrast, certain lipid pairs such as cholesterol and sphingomyelin appear to be in competition at several sites, despite their coexistence in lipid nanodomains. In addition, we observed intralipid competition between two lipid tails, with the receptor exhibiting increased interactions with the unsaturated lipid tails. We believe our work represents an important step in understanding the diversity of GPCR-lipid interactions and exploring synergistic cobinding and competition in natural membranes.
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Affiliation(s)
- Madhura Mohole
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune411 008, India.,Academy of Scientific and Innovative Research, Ghaziabad201 002, India
| | - Durba Sengupta
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune411 008, India.,Academy of Scientific and Innovative Research, Ghaziabad201 002, India
| | - Amitabha Chattopadhyay
- Academy of Scientific and Innovative Research, Ghaziabad201 002, India.,CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad500 007, India
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13
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Sarkar P, Bhat A, Chattopadhyay A. Lysine 101 in the CRAC Motif in Transmembrane Helix 2 Confers Cholesterol-Induced Thermal Stability to the Serotonin 1A Receptor. J Membr Biol 2022; 255:739-746. [PMID: 35986776 DOI: 10.1007/s00232-022-00262-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/05/2022] [Indexed: 12/24/2022]
Abstract
G protein-coupled receptors (GPCRs) constitute the largest class of membrane proteins that transduce signals across the plasma membrane and orchestrate a multitude of physiological processes within cells. The serotonin1A receptor is a crucial neurotransmitter receptor in the GPCR family involved in a multitude of neurological, behavioral and cognitive functions. We have previously shown, using a combination of experimental and simulation approaches, that membrane cholesterol acts as a key regulator of organization, dynamics, signaling and endocytosis of the serotonin1A receptor. In addition, we showed that membrane cholesterol stabilizes the serotonin1A receptor against thermal deactivation. In the present work, we explored the molecular basis of cholesterol-induced thermal stability of the serotonin1A receptor. For this, we explored the possible role of the K101 residue in a cholesterol recognition/interaction amino acid consensus (CRAC) motif in transmembrane helix 2 in conferring the thermal stability of the serotonin1A receptor. Our results show that a mutation in the K101 residue leads to loss in thermal stability of the serotonin1A receptor imparted by cholesterol, independent of membrane cholesterol content. We envision that our results could have potential implications in structural biological advancements of GPCRs and design of thermally stabilized receptors for drug development.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
| | - Akrati Bhat
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
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14
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Szczurowska E, Szánti-Pintér E, Randáková A, Jakubík J, Kudova E. Allosteric Modulation of Muscarinic Receptors by Cholesterol, Neurosteroids and Neuroactive Steroids. Int J Mol Sci 2022; 23:13075. [PMID: 36361865 PMCID: PMC9656441 DOI: 10.3390/ijms232113075] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/21/2022] [Accepted: 10/24/2022] [Indexed: 11/24/2023] Open
Abstract
Muscarinic acetylcholine receptors are membrane receptors involved in many physiological processes. Malfunction of muscarinic signaling is a cause of various internal diseases, as well as psychiatric and neurologic conditions. Cholesterol, neurosteroids, neuroactive steroids, and steroid hormones are molecules of steroid origin that, besides having well-known genomic effects, also modulate membrane proteins including muscarinic acetylcholine receptors. Here, we review current knowledge on the allosteric modulation of muscarinic receptors by these steroids. We give a perspective on the research on the non-genomic effects of steroidal compounds on muscarinic receptors and drug development, with an aim to ultimately exploit such knowledge.
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Affiliation(s)
- Ewa Szczurowska
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo Namesti 2, Prague 6, 166 10 Prague, Czech Republic
| | - Eszter Szánti-Pintér
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo Namesti 2, Prague 6, 166 10 Prague, Czech Republic
| | - Alena Randáková
- Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
| | - Jan Jakubík
- Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo Namesti 2, Prague 6, 166 10 Prague, Czech Republic
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15
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Kotlyarov S, Kotlyarova A. The Importance of the Plasma Membrane in Atherogenesis. MEMBRANES 2022; 12:1036. [PMID: 36363591 PMCID: PMC9698587 DOI: 10.3390/membranes12111036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Atherosclerotic cardiovascular diseases are an important medical problem due to their high prevalence, impact on quality of life and prognosis. The pathogenesis of atherosclerosis is an urgent medical and social problem, the solution of which may improve the quality of diagnosis and treatment of patients. Atherosclerosis is a complex chain of events, which proceeds over many years and in which many cells in the bloodstream and the vascular wall are involved. A growing body of evidence suggests that there are complex, closely linked molecular mechanisms that occur in the plasma membranes of cells involved in atherogenesis. Lipid transport, innate immune system receptor function, and hemodynamic regulation are linked to plasma membranes and their biophysical properties. A better understanding of these interrelationships will improve diagnostic quality and treatment efficacy.
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Affiliation(s)
- Stanislav Kotlyarov
- Department of Nursing, Ryazan State Medical University, 390026 Ryazan, Russia
| | - Anna Kotlyarova
- Department of Pharmacy Management and Economics, Ryazan State Medical University, 390026 Ryazan, Russia
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16
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Schneider EH, Fitzgerald AC, Ponnapula SS, Dopico AM, Bukiya AN. Differential distribution of cholesterol pools across arteries under high-cholesterol diet. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159235. [PMID: 36113825 DOI: 10.1016/j.bbalip.2022.159235] [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: 07/14/2021] [Revised: 08/26/2022] [Accepted: 09/05/2022] [Indexed: 11/19/2022]
Abstract
Excessive cholesterol constitutes a major risk factor for vascular disease. Within cells, cholesterol is distributed in detergent-sensitive and detergent-resistant fractions, with the largest amount of cholesterol residing in cellular membranes. We set out to determine whether various arteries differ in their ability to accumulate esterified and non-esterified cholesterol in detergent-sensitive versus detergent-resistant fractions throughout the course of a high-cholesterol diet. Male Sprague-Dawley rats were placed on 2 % cholesterol diet while a control group was receiving iso-caloric standard chow. Liver, aorta, and pulmonary, mesenteric, and cerebral arteries were collected at 2-6, 8-12, 14-18, and 20-24 weeks from the start of high-cholesterol diet. After fraction separation, esterified and free non-esterified cholesterol levels were measured. In all arteries, largest cholesterol amounts were present in detergent-sensitive fractions in the non-esterified form. Overall, cholesterol in aorta and cerebral arteries was elevated during 14-18 weeks of high-cholesterol diet. Cerebral arteries also exhibited increase in esterified cholesterol within detergent-sensitive domains, as well as increase in cholesterol level in the detergent-resistant fraction at earlier time-points of diet. Pulmonary artery and mesenteric artery were largely resistant to cholesterol accumulation. Quantitative polymerase chain reaction (qPCR) analysis revealed up-regulation of low-density lipoprotein receptor (Ldlr) and low-density lipoprotein receptor-related protein 1 (Lrp1) gene expression in cerebral arteries when compared to mesenteric and pulmonary arteries, respectively. In summary, we unveiled the differential ability of arteries to accumulate cholesterol over the course of a high-cholesterol diet. The differential accumulation of cholesterol seems to correlate with the up-regulated gene expression of proteins responsible for cholesterol uptake.
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Affiliation(s)
- Elizabeth H Schneider
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - Amanda C Fitzgerald
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - Supriya Suzy Ponnapula
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - Alex M Dopico
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - Anna N Bukiya
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, United States.
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17
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Kumari S, Mitra A, Bulusu G. Structural dynamics of Smoothened (SMO) in the ciliary membrane and its interaction with membrane lipids. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183946. [PMID: 35483421 DOI: 10.1016/j.bbamem.2022.183946] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 03/22/2022] [Accepted: 04/18/2022] [Indexed: 06/14/2023]
Abstract
The Smoothened receptor (SMO, a 7 pass transmembrane domain, Class F GPCR family protein) plays a crucial role in the Hedgehog (HH) signaling pathway, which is involved in embryonic development and is implicated in various types of cancer throughout the animal kingdom. In the absence of HH signaling, SMO is inhibited by Patched 1 (PTC1; a 12 pass transmembrane domain protein), which is localized in the primary cilia. HH binding leads to the dislocation of PTC1 from the cilia, thus making way for SMO to localize in the primary cilia, as an essential prerequisite for its activation. We have carried out MARTINI coarse-grained molecular dynamics simulations of SMO in POPC and in ciliary membrane models, respectively, to study the interactions of SMO with cholesterol and other lipid molecules in the ciliary membrane, and to gain molecular-level insights into the role of the primary cilia in shaping the functional dynamics of SMO. We are able to identify the interaction of membrane cholesterols with definite sites and domains within SMO and relate them with known cholesterol-binding sequence and structure motifs. We show that cholesterol interactions with the transmembrane domain TMD, unlike those with the cysteine-rich domain (CRD) and the intracellular domain (ICD), are through residues belonging to known cholesterol-binding motifs. Notably, a few persistent interactions of cholesterol with lower TM cholesterol-binding domains are governed by the presence of multiple cholesterol-binding motifs. These analyses have also helped to identify and define a strict cholesterol consensus motif (CCM), which may well steer cholesterol into the hitherto identified binding sites within the TMD of SMO. We have also reported the interaction of phosphatidylinositol 4-phosphate with the intracellular region of transmembrane (TM) helices (TM1, TM3, TM4, and TM5), intracellular loop1, helix8, and Arg/Lys clusters of the ICD. Structural analysis of SMO domains shows significant changes in the CRD and ICD, during the course of the simulation. Further detailed analysis of the dynamics of the TMD reveals the movements of TM5, TM6, and TM7, linked with the helix8, which are possibly involved in shaping the conformational disposition of the ICD. The movement of these TM helices could possibly be a consequence of interactions involving the extracellular domain and extracellular loops. In addition, our analysis also shows that phosphatidylinositol-4-phosphate (PI4P), along with some ICD cholesterols, are implicated in anchoring SMO in the membrane.
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Affiliation(s)
- Shweta Kumari
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad 500 032, India
| | - Abhijit Mitra
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad 500 032, India
| | - Gopalakrishnan Bulusu
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad 500 032, India; Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad 500 046, India.
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18
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Dutta P, Ray K. Ciliary membrane, localised lipid modification and cilia function. J Cell Physiol 2022; 237:2613-2631. [PMID: 35661356 DOI: 10.1002/jcp.30787] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 05/06/2022] [Accepted: 05/11/2022] [Indexed: 11/08/2022]
Abstract
Cilium, a tiny microtubule-based cellular appendage critical for cell signalling and physiology, displays a large variety of receptors. The composition and turnover of ciliary lipids and receptors determine cell behaviour. Due to the exclusion of ribosomal machinery and limited membrane area, a cilium needs adaptive logistics to actively reconstitute the lipid and receptor compositions during development and differentiation. How is this dynamicity generated? Here, we examine whether, along with the Intraflagellar-Transport, targeted changes in sector-wise lipid composition could control the receptor localisation and functions in the cilia. We discuss how an interplay between ciliary lipid composition, localised lipid modification, and receptor function could contribute to cilia growth and signalling. We argue that lipid modification at the cell-cilium interface could generate an added thrust for a selective exchange of membrane lipids and the transmembrane and membrane-associated proteins.
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Affiliation(s)
- Priya Dutta
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Krishanu Ray
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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19
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Dutta A, Sarkar P, Shrivastava S, Chattopadhyay A. Effect of Hypoxia on the Function of the Human Serotonin 1A Receptor. ACS Chem Neurosci 2022; 13:1456-1466. [PMID: 35467841 DOI: 10.1021/acschemneuro.2c00181] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Cellular hypoxia causes numerous pathophysiological conditions associated with the disruption of oxygen homeostasis. Under oxygen-deficient conditions, cells adapt by controlling the cellular functions to facilitate the judicious use of available oxygen, such as cessation of cell growth and proliferation. In higher eukaryotes, the process of cholesterol biosynthesis is intimately coupled to the availability of oxygen, where the synthesis of one molecule of cholesterol requires 11 molecules of O2. Cholesterol is an essential component of higher eukaryotic membranes and is crucial for the physiological functions of several membrane proteins and receptors. The serotonin1A receptor, an important neurotransmitter G protein-coupled receptor associated with cognition and memory, has previously been shown to depend on cholesterol for its signaling and function. In this work, in order to explore the interdependence of oxygen levels, cholesterol biosynthesis, and the function of the serotonin1A receptor, we developed a cellular hypoxia model to explore the function of the human serotonin1A receptor heterologously expressed in Chinese hamster ovary cells. We observed cell cycle arrest at G1/S phase and the accumulation of lanosterol in cell membranes under hypoxic conditions, thereby validating our cellular model. Interestingly, we observed a significant reduction in ligand binding and disruption of downstream cAMP signaling of the serotonin1A receptor under hypoxic conditions. To the best of our knowledge, our results represent the first report linking the function of the serotonin1A receptor with hypoxia. From a broader perspective, these results contribute to our overall understanding of the molecular basis underlying neurological conditions often associated with hypoxia-induced brain dysfunction.
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Affiliation(s)
- Aritri Dutta
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Sandeep Shrivastava
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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20
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Egyed A, Kiss DJ, Keserű GM. The Impact of the Secondary Binding Pocket on the Pharmacology of Class A GPCRs. Front Pharmacol 2022; 13:847788. [PMID: 35355719 PMCID: PMC8959758 DOI: 10.3389/fphar.2022.847788] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 02/01/2022] [Indexed: 12/19/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are considered important therapeutic targets due to their pathophysiological significance and pharmacological relevance. Class A receptors represent the largest group of GPCRs that gives the highest number of validated drug targets. Endogenous ligands bind to the orthosteric binding pocket (OBP) embedded in the intrahelical space of the receptor. During the last 10 years, however, it has been turned out that in many receptors there is secondary binding pocket (SBP) located in the extracellular vestibule that is much less conserved. In some cases, it serves as a stable allosteric site harbouring allosteric ligands that modulate the pharmacology of orthosteric binders. In other cases it is used by bitopic compounds occupying both the OBP and SBP. In these terms, SBP binding moieties might influence the pharmacology of the bitopic ligands. Together with others, our research group showed that SBP binders contribute significantly to the affinity, selectivity, functional activity, functional selectivity and binding kinetics of bitopic ligands. Based on these observations we developed a structure-based protocol for designing bitopic compounds with desired pharmacological profile.
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Affiliation(s)
| | | | - György M. Keserű
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, Budapest, Hungary
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21
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Żuk J, Bartuzi D, Miszta P, Kaczor AA. The Role of Lipids in Allosteric Modulation of Dopamine D 2 Receptor-In Silico Study. Molecules 2022; 27:molecules27041335. [PMID: 35209123 PMCID: PMC8874991 DOI: 10.3390/molecules27041335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 12/20/2022] Open
Abstract
The dopamine D2 receptor, belonging to the class A G protein-coupled receptors (GPCRs), is an important drug target for several diseases, including schizophrenia and Parkinson’s disease. The D2 receptor can be activated by the natural neurotransmitter dopamine or by synthetic ligands, which in both cases leads to the receptor coupling with a G protein. In addition to receptor modulation by orthosteric or allosteric ligands, it has been shown that lipids may affect the behaviour of membrane proteins. We constructed a model of a D2 receptor with a long intracellular loop (ICL3) coupled with Giα1 or Giα2 proteins, embedded in a complex asymmetric membrane, and simulated it in complex with positive, negative or neutral allosteric ligands. In this study, we focused on the influence of ligand binding and G protein coupling on the membrane–receptor interactions. We show that there is a noticeable interplay between the cell membrane, G proteins, D2 receptor and its modulators.
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Affiliation(s)
- Justyna Żuk
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Laboratory, Faculty of Pharmacy, Medical University of Lublin, 4A Chodźki St., PL-20093 Lublin, Poland; (J.Ż.); (D.B.)
| | - Damian Bartuzi
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Laboratory, Faculty of Pharmacy, Medical University of Lublin, 4A Chodźki St., PL-20093 Lublin, Poland; (J.Ż.); (D.B.)
| | - Przemysław Miszta
- Faculty of Chemistry, Biological, Chemical Research Centre, University of Warsaw, PL-02093 Warsaw, Poland;
| | - Agnieszka A. Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modelling Laboratory, Faculty of Pharmacy, Medical University of Lublin, 4A Chodźki St., PL-20093 Lublin, Poland; (J.Ż.); (D.B.)
- School of Pharmacy, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland
- Correspondence: ; Tel.: +48-81-448-72-73
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22
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Oliveira AA, Róg T, da Silva ABF, Amaro RE, Johnson MS, Postila PA. Examining the Effect of Charged Lipids on Mitochondrial Outer Membrane Dynamics Using Atomistic Simulations. Biomolecules 2022; 12:183. [PMID: 35204684 PMCID: PMC8961577 DOI: 10.3390/biom12020183] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/11/2022] Open
Abstract
The outer mitochondrial membrane (OMM) is involved in multiple cellular functions such as apoptosis, inflammation and signaling via its membrane-associated and -embedded proteins. Despite the central role of the OMM in these vital phenomena, the structure and dynamics of the membrane have regularly been investigated in silico using simple two-component models. Accordingly, the aim was to generate the realistic multi-component model of the OMM and inspect its properties using atomistic molecular dynamics (MD) simulations. All major lipid components, phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS), were included in the probed OMM models. Because increased levels of anionic PS lipids have potential effects on schizophrenia and, more specifically, on monoamine oxidase B enzyme activity, the effect of varying the PS concentration was explored. The MD simulations indicate that the complex membrane lipid composition (MLC) behavior is notably different from the two-component PC-PE model. The MLC changes caused relatively minor effects on the membrane structural properties such as membrane thickness or area per lipid; however, notable effects could be seen with the dynamical parameters at the water-membrane interface. Increase of PS levels appears to slow down lateral diffusion of all lipids and, in general, the presence of anionic lipids reduced hydration and slowed down the PE headgroup rotation. In addition, sodium ions could neutralize the membrane surface, when PI was the main anionic component; however, a similar effect was not seen for high PS levels. Based on these results, it is advisable for future studies on the OMM and its protein or ligand partners, especially when wanting to replicate the correct properties on the water-membrane interface, to use models that are sufficiently complex, containing anionic lipid types, PI in particular.
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Affiliation(s)
- Aline A. Oliveira
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093-0340, USA; (A.A.O.); (R.E.A.)
- Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, São Carlos 13560-970, Brazil;
| | - Tomasz Róg
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland;
| | - Albérico B. F. da Silva
- Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, São Carlos 13560-970, Brazil;
| | - Rommie E. Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093-0340, USA; (A.A.O.); (R.E.A.)
| | - Mark S. Johnson
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland;
- InFLAMES Research Flagship Center, Åbo Akademi University, 20520 Turku, Finland
| | - Pekka A. Postila
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093-0340, USA; (A.A.O.); (R.E.A.)
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland;
- InFLAMES Research Flagship Center, Åbo Akademi University, 20520 Turku, Finland
- Institute of Biomedicine, Kiinamyllynkatu 10, Integrative Physiology and Pharmacy, University of Turku, FI-20520 Turku, Finland
- Aurlide Ltd., FI-21420 Lieto, Finland
- InFLAMES Research Flagship Center, University of Turku, FI-20520 Turku, Finland
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23
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Abstract
Rapid flip-flop of phospholipids across the two leaflets of biological membranes is crucial for many aspects of cellular life. The transport proteins that facilitate this process are classified as pump-like flippases and floppases and channel-like scramblases. Unexpectedly, Class A G protein-coupled receptors (GPCRs), a large class of signaling proteins exemplified by the visual receptor rhodopsin and its apoprotein opsin, are constitutively active as scramblases in vitro. In liposomes, opsin scrambles lipids at a unitary rate of >100,000 per second. Atomistic molecular dynamics simulations of opsin in a lipid membrane reveal conformational transitions that expose a polar groove between transmembrane helices 6 and 7. This groove enables transbilayer lipid movement, conceptualized as the swiping of a credit card (lipid) through a card reader (GPCR). Conformational changes that facilitate scrambling are distinct from those associated with GPCR signaling. In this review, we discuss the physiological significance of GPCR scramblase activity and the modes of its regulation in cells. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, USA; .,Institute of Computational Biomedicine, Weill Cornell Medical College, New York, New York, USA
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA;
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24
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Cholesterol-dependent endocytosis of GPCRs: implications in pathophysiology and therapeutics. Biophys Rev 2021; 13:1007-1017. [DOI: 10.1007/s12551-021-00878-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/26/2021] [Indexed: 10/19/2022] Open
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25
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Cholesterol in GPCR Structures: Prevalence and Relevance. J Membr Biol 2021; 255:99-106. [PMID: 34365520 DOI: 10.1007/s00232-021-00197-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/27/2021] [Indexed: 12/14/2022]
Abstract
Bound cholesterol molecules are emerging as important hallmarks of GPCR structures. In this commentary, we analyze their statistical prevalence and biological relevance.
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26
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Kunselman JM, Lott J, Puthenveedu MA. Mechanisms of selective G protein-coupled receptor localization and trafficking. Curr Opin Cell Biol 2021; 71:158-165. [PMID: 33965654 PMCID: PMC8328924 DOI: 10.1016/j.ceb.2021.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 03/09/2021] [Indexed: 12/21/2022]
Abstract
The trafficking of G protein-coupled receptors (GPCRs) to different membrane compartments has recently emerged as being a critical determinant of the signaling profiles of activation. GPCRs, which share many structural and functional similarities, also share many mechanisms that traffic them between compartments. This sharing raises the question of how the trafficking of individual GPCRs is selectively regulated. Here, we will discuss recent studies addressing the mechanisms that contribute to selectivity in endocytic and biosynthetic trafficking of GPCRs.
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Affiliation(s)
- Jennifer M Kunselman
- Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Joshua Lott
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Manojkumar A Puthenveedu
- Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, USA; Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA.
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27
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Sarkar P, Chattopadhyay A. Cholesterol footprint in high-resolution structures of serotonin receptors: Where are we now and what does it mean? Chem Phys Lipids 2021; 239:105120. [PMID: 34332970 DOI: 10.1016/j.chemphyslip.2021.105120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/24/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
An emerging feature of several high-resolution GPCR structures is the presence of closely bound cholesterol molecules. In this Perspective, we share the excitement of the recent advancements in GPCR structural biology. We further highlight our laboratory's journey in comprehensively elucidating functional sensitivity of GPCRs (using the serotonin1A receptor as a representative neurotransmitter GPCR) to membrane cholesterol and validation using a variety of assays and molecular dynamics simulations. Although high-resolution structures of many GPCRs have been reported in the last few years, the structure of the serotoin1A receptor proved to be elusive for a long time. Very recently the cryo-EM structure of the serotoin1A receptor displaying 10 bound cholesterol molecules has been reported. We conclude by providing a critical analysis of caveats involved in GPCR structure determination.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
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28
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van Aalst E, Koneri J, Wylie BJ. In Silico Identification of Cholesterol Binding Motifs in the Chemokine Receptor CCR3. MEMBRANES 2021; 11:570. [PMID: 34436333 PMCID: PMC8401243 DOI: 10.3390/membranes11080570] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 01/14/2023]
Abstract
CC motif chemokine receptor 3 (CCR3) is a Class A G protein-coupled receptor (GPCR) mainly responsible for the cellular trafficking of eosinophils. As such, it plays key roles in inflammatory conditions, such as asthma and arthritis, and the metastasis of many deadly forms of cancer. However, little is known about how CCR3 functionally interacts with its bilayer environment. Here, we investigate cholesterol binding sites in silico through Coarse-Grained Molecular Dynamics (MD) and Pylipid analysis using an extensively validated homology model based on the crystal structure of CCR5. These simulations identified several cholesterol binding sites containing Cholesterol Recognition/Interaction Amino Acid Consensus motif (CRAC) and its inversion CARC motifs in CCR3. One such site, a CARC site in TM1, in conjunction with aliphatic residues in TM7, emerged as a candidate for future investigation based on the cholesterol residency time within the binding pocket. This site forms the core of a cholesterol binding site previously observed in computational studies of CCR2 and CCR5. Most importantly, these cholesterol binding sites are conserved in other chemokine receptors and may provide clues to cholesterol regulation mechanisms in this subfamily of Class A GPCRs.
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Affiliation(s)
| | | | - Benjamin J. Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79423, USA; (E.v.A.); (J.K.)
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Kumar GA, Sarkar P, Stepniewski TM, Jafurulla M, Singh SP, Selent J, Chattopadhyay A. A molecular sensor for cholesterol in the human serotonin 1A receptor. SCIENCE ADVANCES 2021; 7:7/30/eabh2922. [PMID: 34301606 PMCID: PMC8302130 DOI: 10.1126/sciadv.abh2922] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/09/2021] [Indexed: 05/10/2023]
Abstract
The function of several G protein-coupled receptors (GPCRs) exhibits cholesterol sensitivity. Cholesterol sensitivity of GPCRs could be attributed to specific sequence and structural features, such as the cholesterol recognition/interaction amino acid consensus (CRAC) motif, that facilitate their cholesterol-receptor interaction. In this work, we explored the molecular basis of cholesterol sensitivity exhibited by the serotonin1A receptor, the most studied GPCR in the context of cholesterol sensitivity, by generating mutants of key residues in CRAC motifs in transmembrane helix 2 (TM2) and TM5 of the receptor. Our results show that a lysine residue (K101) in one of the CRAC motifs is crucial for sensing altered membrane cholesterol levels. Insights from all-atom molecular dynamics simulations showed that cholesterol-sensitive functional states of the serotonin1A receptor are associated with reduced conformational dynamics of extracellular loops of the receptor. These results constitute one of the first reports on the molecular mechanism underlying cholesterol sensitivity of GPCRs.
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Affiliation(s)
- G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Tomasz Maciej Stepniewski
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Md Jafurulla
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Shishu Pal Singh
- National Centre for Biological Sciences, UAS-GKVK Campus, Bellary Road, Bengaluru 560 065, India
| | - 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), 08003 Barcelona, Spain.
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30
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Wu Y, Zeng L, Zhao S. Ligands of Adrenergic Receptors: A Structural Point of View. Biomolecules 2021; 11:936. [PMID: 34202543 PMCID: PMC8301793 DOI: 10.3390/biom11070936] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/09/2021] [Accepted: 06/12/2021] [Indexed: 01/14/2023] Open
Abstract
Adrenergic receptors are G protein-coupled receptors for epinephrine and norepinephrine. They are targets of many drugs for various conditions, including treatment of hypertension, hypotension, and asthma. Adrenergic receptors are intensively studied in structural biology, displayed for binding poses of different types of ligands. Here, we summarized molecular mechanisms of ligand recognition and receptor activation exhibited by structure. We also reviewed recent advances in structure-based ligand discovery against adrenergic receptors.
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Affiliation(s)
- Yiran Wu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China; (Y.W.); (L.Z.)
| | - Liting Zeng
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China; (Y.W.); (L.Z.)
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Suwen Zhao
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China; (Y.W.); (L.Z.)
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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31
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Kumar A, Sarkar P, Chattopadhyay A. Metabolic Depletion of Sphingolipids Reduces Cell Surface Population of the Human Serotonin 1A Receptor due to Impaired Trafficking. ACS Chem Neurosci 2021; 12:1189-1196. [PMID: 33760584 DOI: 10.1021/acschemneuro.1c00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sphingolipids and their metabolites are increasingly implicated in the pathogenesis of many metabolic and neurological diseases. It has been postulated that sphingolipids coalesce with cholesterol to form laterally segregated lipid domains that are involved in protein sorting and trafficking. In this work, we have explored the effect of metabolic depletion of sphingolipids on cell surface expression of the human serotonin1A receptor, a neurotransmitter G protein-coupled receptor. We used fumonisin B1 (FB1), a fungal mycotoxin, to inhibit sphingolipid biosynthesis in HEK-293 cells stably expressing the human serotonin1A receptor. Our results obtained using flow cytometric analysis and confocal microscopic imaging show that the cell surface population of the serotonin1A receptor is reduced under sphingolipid-depleted condition. Western blot analysis confirmed that there was no significant difference in total cellular level of the serotonin1A receptor upon depletion of sphingolipids. Interestingly, the effect of FB1 on serotonin1A receptor population was reversed upon replenishment with sphingolipids. These results indicate that sphingolipid depletion does not alter total cellular receptor levels, but impairs serotonin1A receptor trafficking to the cellular plasma membrane. These results could provide mechanistic insights into the role of sphingolipids in modulation of neurotransmitter receptor signaling and trafficking in health and disease.
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Affiliation(s)
- Abhishek Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- Amity Institute of Biotechnology, Amity University Haryana, Amity Education Valley, Gurugram 122 413, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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32
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Dingjan T, Futerman AH. The fine-tuning of cell membrane lipid bilayers accentuates their compositional complexity. Bioessays 2021; 43:e2100021. [PMID: 33656770 DOI: 10.1002/bies.202100021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 01/17/2023]
Abstract
Cell membranes are now emerging as finely tuned molecular systems, signifying that re-evaluation of our understanding of their structure is essential. Although the idea that cell membrane lipid bilayers do little more than give shape and form to cells and limit diffusion between cells and their environment is totally passé, the structural, compositional, and functional complexity of lipid bilayers often catches cell and molecular biologists by surprise. Models of lipid bilayer structure have developed considerably since the heyday of the fluid mosaic model, principally by the discovery of the restricted diffusion of membrane proteins and lipids within the plane of the bilayer. In reviewing this field, we now suggest that further refinement of current models is necessary and propose that describing lipid bilayers as "finely-tuned molecular assemblies" best portrays their complexity and function. Also see the video abstract here: https://www.youtube.com/watch?v=ddkP-QRZTl8.
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Affiliation(s)
- Tamir Dingjan
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Anthony H Futerman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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33
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Jakubík J, El-Fakahany EE. Allosteric Modulation of GPCRs of Class A by Cholesterol. Int J Mol Sci 2021; 22:1953. [PMID: 33669406 PMCID: PMC7920425 DOI: 10.3390/ijms22041953] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/16/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are membrane proteins that convey extracellular signals to the cellular milieu. They represent a target for more than 30% of currently marketed drugs. Here we review the effects of membrane cholesterol on the function of GPCRs of Class A. We review both the specific effects of cholesterol mediated via its direct high-affinity binding to the receptor and non-specific effects mediated by cholesterol-induced changes in the properties of the membrane. Cholesterol binds to many GPCRs at both canonical and non-canonical binding sites. It allosterically affects ligand binding to and activation of GPCRs. Additionally, it changes the oligomerization state of GPCRs. In this review, we consider a perspective of the potential for the development of new therapies that are targeted at manipulating the level of membrane cholesterol or modulating cholesterol binding sites on to GPCRs.
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Affiliation(s)
- Jan Jakubík
- Department of Neurochemistry, Institute of Physiology Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Esam E. El-Fakahany
- Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN 55455, USA
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34
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Pawar AB, Sengupta D. Role of Cholesterol in Transmembrane Dimerization of the ErbB2 Growth Factor Receptor. J Membr Biol 2021; 254:301-310. [PMID: 33506276 DOI: 10.1007/s00232-021-00168-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/05/2021] [Indexed: 11/28/2022]
Abstract
The association of ErbB2 growth factor receptors is critical for cell growth and potentiates tumor proliferation in several cancer types. An important aspect in ErbB2 association is the role of lipids such as cholesterol, especially since their metabolism is often reprogrammed in cancer cells. Here, we have coupled metadynamics with coarse-grain simulations to identify cholesterol effects in the transmembrane dimerization of ErbB2 receptors. Overall, cholesterol interactions are observed with the receptor that directly tunes the association energetics. Several dimer conformations are identified both in the presence and absence of cholesterol, although the dimer regime appears to be more favorable in the presence of cholesterol. We observe an overall modulation of the underlying energy profile and the symmetric active and inactive conformational states are not distinguished in the presence of cholesterol. We show that cholesterol binds to the receptor transmembrane domain at a site (CRAC motif) that overlaps with the dimer interface (SmXXXSm motif). The competition between the transmembrane interactions and cholesterol interactions decides the final conformational landscape. Our work is an important step toward characterizing cholesterol effects in ErbB2 membrane receptor function.
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Affiliation(s)
- Aiswarya B Pawar
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Durba Sengupta
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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35
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Sarkar P, Mozumder S, Bej A, Mukherjee S, Sengupta J, Chattopadhyay A. Structure, dynamics and lipid interactions of serotonin receptors: excitements and challenges. Biophys Rev 2020; 13:10.1007/s12551-020-00772-8. [PMID: 33188638 PMCID: PMC7930197 DOI: 10.1007/s12551-020-00772-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/05/2020] [Indexed: 12/13/2022] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is an intrinsically fluorescent neurotransmitter found in organisms spanning a wide evolutionary range. Serotonin exerts its diverse actions by binding to distinct cell membrane receptors which are classified into many groups. Serotonin receptors are involved in regulating a diverse array of physiological signaling pathways and belong to the family of either G protein-coupled receptors (GPCRs) or ligand-gated ion channels. Serotonergic signaling appears to play a key role in the generation and modulation of various cognitive and behavioral functions such as sleep, mood, pain, anxiety, depression, aggression, and learning. Serotonin receptors act as drug targets for a number of diseases, particularly neuropsychiatric disorders. The signaling mechanism and efficiency of serotonin receptors depend on their amazing ability to rapidly access multiple conformational states. This conformational plasticity, necessary for the wide variety of functions displayed by serotonin receptors, is regulated by binding to various ligands. In this review, we provide a succinct overview of recent developments in generating and analyzing high-resolution structures of serotonin receptors obtained using crystallography and cryo-electron microscopy. Capturing structures of distinct conformational states is crucial for understanding the mechanism of action of these receptors, which could provide important insight for rational drug design targeting serotonin receptors. We further provide emerging information and insight from studies on interactions of membrane lipids (such as cholesterol) with serotonin receptors. We envision that a judicious combination of analysis of high-resolution structures and receptor-lipid interaction would allow a comprehensive understanding of GPCR structure, function and dynamics, thereby leading to efficient drug discovery.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
| | - Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201 002, India
| | - Aritra Bej
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
| | - Sujoy Mukherjee
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201 002, India
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36
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Jones AJY, Gabriel F, Tandale A, Nietlispach D. Structure and Dynamics of GPCRs in Lipid Membranes: Physical Principles and Experimental Approaches. Molecules 2020; 25:E4729. [PMID: 33076366 PMCID: PMC7587580 DOI: 10.3390/molecules25204729] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/11/2020] [Accepted: 10/12/2020] [Indexed: 02/06/2023] Open
Abstract
Over the past decade, the vast amount of information generated through structural and biophysical studies of GPCRs has provided unprecedented mechanistic insight into the complex signalling behaviour of these receptors. With this recent information surge, it has also become increasingly apparent that in order to reproduce the various effects that lipids and membranes exert on the biological function for these allosteric receptors, in vitro studies of GPCRs need to be conducted under conditions that adequately approximate the native lipid bilayer environment. In the first part of this review, we assess some of the more general effects that a membrane environment exerts on lipid bilayer-embedded proteins such as GPCRs. This is then followed by the consideration of more specific effects, including stoichiometric interactions with specific lipid subtypes. In the final section, we survey a range of different membrane mimetics that are currently used for in vitro studies, with a focus on NMR applications.
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Affiliation(s)
| | | | | | - Daniel Nietlispach
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK; (A.J.Y.J.); (F.G.); (A.T.)
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37
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Kurth M, Lolicato F, Sandoval-Perez A, Amaya-Espinosa H, Teslenko A, Sinning I, Beck R, Brügger B, Aponte-Santamaría C. Cholesterol Localization around the Metabotropic Glutamate Receptor 2. J Phys Chem B 2020; 124:9061-9078. [PMID: 32954729 DOI: 10.1021/acs.jpcb.0c05264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabotropic glutamate receptor (mGluR) 2 plays a key role in the central nervous system. mGluR2 has been shown to be regulated by its surrounding lipid environment, especially by cholesterol, by an unknown mechanism. Here, using a combination of biochemical approaches, photo-cross-linking experiments, and molecular dynamics simulations we show the interaction of cholesterol with at least two, but potentially five more, preferential sites on the mGluR2 transmembrane domain. Our simulations demonstrate that surface matching, rather than electrostatic interactions with specific amino acids, is the main factor defining cholesterol localization. Moreover, the cholesterol localization observed here is similar to the sterol-binding pattern previously described in silico for other members of the mGluR family. Biochemical assays suggest little influence of cholesterol on trafficking or dimerization of mGluR2. Nevertheless, simulations revealed a significant reduction of residue-residue contacts together with an alteration in the internal mechanical stress at the cytoplasmic side of the helical bundle when cholesterol was present in the membrane. These alterations may be related to destabilization of the basal state of mGluR2. Due to the high sequence conservation of the transmembrane domains of mGluRs, the molecular interaction of cholesterol and mGluR2 described here is also likely to be relevant for other members of the mGLuR family.
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Affiliation(s)
- Markus Kurth
- Biochemistry Center (BZH), Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Fabio Lolicato
- Biochemistry Center (BZH), Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Angelica Sandoval-Perez
- Max Planck Tandem Group in Computational Biophysics, University of Los Andes, Bogotá, Colombia
| | - Helman Amaya-Espinosa
- Max Planck Tandem Group in Computational Biophysics, University of Los Andes, Bogotá, Colombia
| | - Alexandra Teslenko
- Biochemistry Center (BZH), Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Irmgard Sinning
- Biochemistry Center (BZH), Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Rainer Beck
- Biochemistry Center (BZH), Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Britta Brügger
- Biochemistry Center (BZH), Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Camilo Aponte-Santamaría
- Max Planck Tandem Group in Computational Biophysics, University of Los Andes, Bogotá, Colombia.,Interdisciplinary Center for Scientific Computing, University of Heidelberg, Heidelberg, Germany
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38
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Sutkeviciute I, Vilardaga JP. Structural insights into emergent signaling modes of G protein-coupled receptors. J Biol Chem 2020; 295:11626-11642. [PMID: 32571882 DOI: 10.1074/jbc.rev120.009348] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 06/21/2020] [Indexed: 12/21/2022] Open
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of cell membrane proteins, with >800 GPCRs in humans alone, and recognize highly diverse ligands, ranging from photons to large protein molecules. Very important to human medicine, GPCRs are targeted by about 35% of prescription drugs. GPCRs are characterized by a seven-transmembrane α-helical structure, transmitting extracellular signals into cells to regulate major physiological processes via heterotrimeric G proteins and β-arrestins. Initially viewed as receptors whose signaling via G proteins is delimited to the plasma membrane, it is now recognized that GPCRs signal also at various intracellular locations, and the mechanisms and (patho)physiological relevance of such signaling modes are actively investigated. The propensity of GPCRs to adopt different signaling modes is largely encoded in the structural plasticity of the receptors themselves and of their signaling complexes. Here, we review emerging modes of GPCR signaling via endosomal membranes and the physiological implications of such signaling modes. We further summarize recent structural insights into mechanisms of GPCR activation and signaling. We particularly emphasize the structural mechanisms governing the continued GPCR signaling from endosomes and the structural aspects of the GPCR resensitization mechanism and discuss the recently uncovered and important roles of lipids in these processes.
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Affiliation(s)
- Ieva Sutkeviciute
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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