1
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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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2
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Lauwers C, De Bruyn L, Langouche L. Impact of critical illness on cholesterol and fatty acids: insights into pathophysiology and therapeutic targets. Intensive Care Med Exp 2023; 11:84. [PMID: 38015312 PMCID: PMC10684846 DOI: 10.1186/s40635-023-00570-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/21/2023] [Indexed: 11/29/2023] Open
Abstract
Critical illness is characterized by a hypercatabolic response encompassing endocrine and metabolic alterations. Not only the uptake, synthesis and metabolism of glucose and amino acids is majorly affected, but also the homeostasis of lipids and cholesterol is altered during acute and prolonged critical illness. Patients who suffer from critically ill conditions such as sepsis, major trauma, surgery or burn wounds display an immediate and sustained reduction in low plasma LDL-, HDL- and total cholesterol concentrations, together with a, less pronounced, increase in plasma free fatty acids. The severity of these alterations is associated with severity of illness, but the underlying pathophysiological mechanisms are multifactorial and only partly clarified. This narrative review aims to provide an overview of the current knowledge of how lipid and cholesterol uptake, synthesis and metabolism is affected during critical illness. Reduced nutritional uptake, increased scavenging of lipoproteins as well as an increased conversion to cortisol or other cholesterol-derived metabolites might all play a role in the decrease in plasma cholesterol. The acute stress response to critical illness creates a lipolytic cocktail, which might explain the increase in plasma free fatty acids, although reduced uptake and oxidation, but also increased lipogenesis, especially in prolonged critical illness, will also affect the circulating levels. Whether a disturbed lipid homeostasis warrants intervention or should primarily be interpreted as a signal of severity of illness requires further research.
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Affiliation(s)
- Caroline Lauwers
- Clinical Division and Laboratory of Intensive Care Medicine, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, O&N1 Box 503, 3000, Leuven, Belgium
| | - Lauren De Bruyn
- Clinical Division and Laboratory of Intensive Care Medicine, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, O&N1 Box 503, 3000, Leuven, Belgium
| | - Lies Langouche
- Clinical Division and Laboratory of Intensive Care Medicine, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, O&N1 Box 503, 3000, Leuven, Belgium.
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3
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Sarkar P, Chattopadhyay A. Interplay of Cholesterol and Actin in Neurotransmitter GPCR Signaling: Insights from Chronic Cholesterol Depletion Using Statin. ACS Chem Neurosci 2023; 14:3855-3868. [PMID: 37804226 DOI: 10.1021/acschemneuro.3c00472] [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] [Indexed: 10/09/2023] Open
Abstract
Serotonin1A receptors are important neurotransmitter receptors in the G protein-coupled receptor (GPCR) family and modulate a variety of neurological, behavioral, and cognitive functions. We recently showed that chronic cholesterol depletion by statins, potent inhibitors of HMG-CoA reductase (the rate-limiting enzyme in cholesterol biosynthesis), leads to polymerization of the actin cytoskeleton that alters lateral diffusion of serotonin1A receptors. However, cellular signaling by the serotonin1A receptor under chronic cholesterol depletion remains unexplored. In this work, we explored signaling by the serotonin1A receptor under statin-treated condition. We show that cAMP signaling by the receptor is reduced upon lovastatin treatment due to reduction in cholesterol as well as polymerization of the actin cytoskeleton. To the best of our knowledge, these results constitute the first report describing the effect of chronic cholesterol depletion on the signaling of a G protein-coupled neuronal receptor. An important message arising from these results is that it is prudent to include the contribution of actin polymerization while analyzing changes in membrane protein function due to chronic cholesterol depletion by statins. Notably, our results show that whereas actin polymerization acts as a negative regulator of cAMP signaling, cholesterol could act as a positive modulator. These results assume significance in view of reports highlighting symptoms of anxiety and depression in humans upon statin administration and the role of serotonin1A receptors in anxiety and depression. Overall, these results reveal a novel role of actin polymerization induced by chronic cholesterol depletion in modulating GPCR signaling, which could act as a potential therapeutic target.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research, Ghaziabad 201 002, India
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4
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Mu J, Xue C, Fu L, Yu Z, Nie M, Wu M, Chen X, Liu K, Bu R, Huang Y, Yang B, Han J, Jiang Q, Chan KC, Zhou R, Li H, Huang A, Wang Y, Liu Z. Conformational cycle of human polyamine transporter ATP13A2. Nat Commun 2023; 14:1978. [PMID: 37031211 PMCID: PMC10082790 DOI: 10.1038/s41467-023-37741-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 03/28/2023] [Indexed: 04/10/2023] Open
Abstract
Dysregulation of polyamine homeostasis strongly associates with human diseases. ATP13A2, which is mutated in juvenile-onset Parkinson's disease and autosomal recessive spastic paraplegia 78, is a transporter with a critical role in balancing the polyamine concentration between the lysosome and the cytosol. Here, to better understand human ATP13A2-mediated polyamine transport, we use single-particle cryo-electron microscopy to solve high-resolution structures of human ATP13A2 in six intermediate states, including the putative E2 structure for the P5 subfamily of the P-type ATPases. These structures comprise a nearly complete conformational cycle spanning the polyamine transport process and capture multiple substrate binding sites distributed along the transmembrane regions, suggesting a potential polyamine transport pathway. Integration of high-resolution structures, biochemical assays, and molecular dynamics simulations allows us to obtain a better understanding of the structural basis of how hATP13A2 transports polyamines, providing a mechanistic framework for ATP13A2-related diseases.
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Affiliation(s)
- Jianqiang Mu
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Chenyang Xue
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Lei Fu
- Shanghai Institute for Advanced Study, Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, 310027, Hangzhou, China
| | - Zongjun Yu
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Minhan Nie
- School of Pharmaceutical Sciences, Sun Yat-sen University, No.132 Wai Huan Dong Lu, Guangzhou Higher Education Mega Center, 510006, Guangzhou, China
| | - Mengqi Wu
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Xinmeng Chen
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Kun Liu
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Ruiqian Bu
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Ying Huang
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Baisheng Yang
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Jianming Han
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Qianru Jiang
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Kevin C Chan
- Shanghai Institute for Advanced Study, Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, 310027, Hangzhou, China
| | - Ruhong Zhou
- Shanghai Institute for Advanced Study, Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, 310027, Hangzhou, China
| | - Huilin Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, No.132 Wai Huan Dong Lu, Guangzhou Higher Education Mega Center, 510006, Guangzhou, China
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006, Guangzhou, Guangdong, China
| | - Ancheng Huang
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Yong Wang
- Shanghai Institute for Advanced Study, Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, 310027, Hangzhou, China.
- The Provincial International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, 314400, Haining, China.
| | - Zhongmin Liu
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China.
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Chattopadhyay A, Sharma A. Smith-Lemli-Opitz syndrome: A pathophysiological manifestation of the Bloch hypothesis. Front Mol Biosci 2023; 10:1120373. [PMID: 36714259 PMCID: PMC9878332 DOI: 10.3389/fmolb.2023.1120373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 01/02/2023] [Indexed: 01/15/2023] Open
Abstract
The biosynthesis of cholesterol, an essential component of higher eukaryotic membranes, was worked out by Konrad Bloch (and Feodor Lynen) in the 1960s and they received the Nobel Prize around that time in recognition of their pioneering contributions. An elegant consequence of this was a hypothesis proposed by Konrad Bloch (the Bloch hypothesis) which suggests that each subsequent intermediate in the cholesterol biosynthesis pathway is superior in supporting membrane function in higher eukaryotes relative to its precursor. In this review, we discuss an autosomal recessive metabolic disorder, known as Smith-Lemli-Opitz syndrome (SLOS), associated with a defect in the Kandutsch-Russell pathway of cholesterol biosynthesis that results in accumulation of the immediate precursor of cholesterol in its biosynthetic pathway (7-dehydrocholesterol) and an altered cholesterol to total sterol ratio. Patients suffering from SLOS have several developmental, behavioral and cognitive abnormalities for which no drug is available yet. We characterize SLOS as a manifestation of the Bloch hypothesis and review its molecular etiology and current treatment. We further discuss defective Hedgehog signaling in SLOS and focus on the role of the serotonin1A receptor, a representative neurotransmitter receptor belonging to the GPCR family, in SLOS. Notably, ligand binding activity and cellular signaling of serotonin1A receptors are impaired in SLOS-like condition. Importantly, cellular localization and intracellular trafficking of the serotonin1A receptor (which constitute an important determinant of a GPCR cellular function) are compromised in SLOS. We highlight some of the recent developments and emerging concepts in SLOS pathobiology and suggest that novel therapies based on trafficking defects of target receptors could provide new insight into treatment of SLOS.
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Affiliation(s)
- Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India,Academy of Scientific and Innovative Research, Ghaziabad, India,*Correspondence: Amitabha Chattopadhyay,
| | - Ashwani Sharma
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India,Academy of Scientific and Innovative Research, Ghaziabad, India
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6
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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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7
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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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8
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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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9
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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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10
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Nicolson GL, Ferreira de Mattos G, Ash M, Settineri R, Escribá PV. Fundamentals of Membrane Lipid Replacement: A Natural Medicine Approach to Repairing Cellular Membranes and Reducing Fatigue, Pain, and Other Symptoms While Restoring Function in Chronic Illnesses and Aging. MEMBRANES 2021; 11:944. [PMID: 34940446 PMCID: PMC8707623 DOI: 10.3390/membranes11120944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 11/23/2021] [Accepted: 11/23/2021] [Indexed: 12/14/2022]
Abstract
Membrane Lipid Replacement (MLR) uses natural membrane lipid supplements to safely replace damaged, oxidized lipids in membranes in order to restore membrane function, decrease symptoms and improve health. Oral MLR supplements contain mixtures of cell membrane glycerolphospholipids, fatty acids, and other lipids, and can be used to replace and remove damaged cellular and intracellular membrane lipids. Membrane injury, caused mainly by oxidative damage, occurs in essentially all chronic and acute medical conditions, including cancer and degenerative diseases, and in normal processes, such as aging and development. After ingestion, the protected MLR glycerolphospholipids and other lipids are dispersed, absorbed, and internalized in the small intestines, where they can be partitioned into circulating lipoproteins, globules, liposomes, micelles, membranes, and other carriers and transported in the lymphatics and blood circulation to tissues and cellular sites where they are taken in by cells and partitioned into various cellular membranes. Once inside cells, the glycerolphospholipids and other lipids are transferred to various intracellular membranes by lipid carriers, globules, liposomes, chylomicrons, or by direct membrane-membrane interactions. The entire process appears to be driven by 'bulk flow' or mass action principles, where surplus concentrations of replacement lipids can stimulate the natural exchange and removal of damaged membrane lipids while the replacement lipids undergo further enzymatic alterations. Clinical studies have demonstrated the advantages of MLR in restoring membrane and organelle function and reducing fatigue, pain, and other symptoms in chronic illness and aging patients.
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Affiliation(s)
- Garth L. Nicolson
- Department of Molecular Pathology, The Institute for Molecular Medicine, Huntington Beach, CA 92647, USA
| | - Gonzalo Ferreira de Mattos
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Department of Biophysics, Facultad de Medicina, Universidad de la República, Montevideo 11600, Uruguay;
| | - Michael Ash
- Clinical Education, Newton Abbot, Devon TQ12 4SG, UK;
| | | | - Pablo V. Escribá
- Laboratory of Molecular Cell Biomedicine, University of the Balearic Islands, 07122 Palma de Mallorca, Spain;
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11
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Hofmaenner DA, Kleyman A, Press A, Bauer M, Singer M. The Many Roles of Cholesterol in Sepsis: A Review. Am J Respir Crit Care Med 2021; 205:388-396. [PMID: 34715007 DOI: 10.1164/rccm.202105-1197tr] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The biological functions of cholesterol are diverse, ranging from cell membrane integrity and signalling, immunity, to the synthesis of steroid and sex hormones, Vitamin D, bile acids and oxysterols. Multiple studies have demonstrated hypocholesterolemia in sepsis, the degree of which is an excellent prognosticator of poor outcomes. However, the clinical significance of hypocholesterolemia has been largely unrecognized. OBJECTIVES/METHODS We undertook a detailed review of the biological roles of cholesterol, the impact of sepsis, its reliability as a prognosticator in sepsis, and the potential utility of cholesterol as a treatment. MEASUREMENTS AND MAIN RESULTS Sepsis affects cholesterol synthesis, transport and metabolism. This likely impacts upon its biological functions including immunity, hormone and vitamin production, and cell membrane receptor sensitivity. Early preclinical studies show promise for cholesterol as a pleiotropic therapeutic agent. CONCLUSIONS Hypocholesterolemia is a frequent condition in sepsis and an important early prognosticator. Low plasma levels are associated with wider changes in cholesterol metabolism and its functional roles, and these appear to play a significant role in sepsis pathophysiology. The therapeutic impact of cholesterol elevation warrants further investigation.
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Affiliation(s)
- Daniel A Hofmaenner
- University College London, 4919, Bloomsbury Inst of Intensive Care Medicine, London, United Kingdom of Great Britain and Northern Ireland.,University Hospital Zurich, Institute of Intensive Care Medicine, Zurich, Switzerland
| | - Anna Kleyman
- University College London, 4919, Bloomsbury Inst of Intensive Care Medicine, London, United Kingdom of Great Britain and Northern Ireland
| | - Adrian Press
- Jena University Hospital Center for Sepsis Control and Care, 553346, Jena, Germany
| | - Michael Bauer
- University Hospital Jena, Dep. of Anesthesiology and Intensive Care Medicine, Jena, Germany
| | - Mervyn Singer
- University College London, 4919, Bloomsbury Inst of Intensive Care Medicine, London, United Kingdom of Great Britain and Northern Ireland;
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12
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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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13
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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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14
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Bhuyan NN, Pattnaik GP, Mishra A, Chakraborty H. Exploring membrane viscosity at the headgroup region utilizing a hemicyanine-based fluorescent probe. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.115152] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Leutner M, Matzhold C, Kautzky A, Kaleta M, Thurner S, Klimek P, Kautzky-Willer A. Major Depressive Disorder (MDD) and Antidepressant Medication Are Overrepresented in High-Dose Statin Treatment. Front Med (Lausanne) 2021; 8:608083. [PMID: 33644093 PMCID: PMC7904887 DOI: 10.3389/fmed.2021.608083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 01/12/2021] [Indexed: 01/24/2023] Open
Abstract
Objective: To examine the dose-dependent relationship of different types of statins with the occurrence of major depressive disorder (MDD) and prescription of antidepressant medication. Methods: This cross-sectional study used medical claims data for the general Austrian population (n = 7,481,168) to identify all statin-treated patients. We analyzed all patients with MDD undergoing statin treatment and calculated the average defined daily dose for six different types of statins. In a sub-analysis conducted independently of inpatient care, we investigated all patients on antidepressant medication (statin-treated patients: n = 98,913; non-statin-treated patients: n = 789,683). Multivariate logistic regression analyses were conducted to calculate the risk of diagnosed MDD and prescription of antidepressant medication in patients treated with different types of statins and dosages compared to non-statin-treated patients. Results: In this study, there was an overrepresentation of MDD in statin-treated patients when compared to non-statin-treated patients (OR: 1.22, 95% CI: 1.20–1.25). However, there was a dose dependent relationship between statins and diagnosis of MDD. Compared to controls, the ORs of MDD were lower for low-dose statin-treated patients (simvastatin>0– < =10 mg:OR: 0.59, 95% CI: 0.54–0.64; atorvastatin>0– < =10 mg:OR:0.65, 95%CI: 0.59–0.70; rosuvastatin>0– < =10 mg:OR: 0.68, 95% CI: 0.53–0.85). In higher statin dosages there was an overrepresentation of MDD (simvastatin>40– < =60 mg:OR: 2.42, 95% CI: 2.18–2.70, >60–80 mg:OR: 5.27, 95% CI: 4.21–6.60; atorvastatin>40– < =60 mg:OR: 2.71, 95% CI: 1.98–3.72, >60– < =80 mg:OR: 3.73, 95% CI: 2.22–6.28; rosuvastatin>20– < =40 mg:OR: 2.09, 95% CI: 1.31–3.34). The results were confirmed in a sex-specific analysis and in a cohort of patients taking antidepressants, prescribed independently of inpatient care. Conclusions: This study shows that it is important to carefully re-investigate the relationship between statins and MDD. High-dose statin treatment was related to an overrepresentation, low-dose statin treatment to an underrepresentation of MDD.
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Affiliation(s)
- Michael Leutner
- Clinical Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Caspar Matzhold
- Section for Science of Complex Systems, Center for Medical Statistics, Informatics, and Intelligent Systems (CeMSIIS), Medical University of Vienna, Vienna, Austria.,Complexity Science Hub Vienna, Vienna, Austria
| | - Alexander Kautzky
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Michaela Kaleta
- Section for Science of Complex Systems, Center for Medical Statistics, Informatics, and Intelligent Systems (CeMSIIS), Medical University of Vienna, Vienna, Austria.,Complexity Science Hub Vienna, Vienna, Austria
| | - Stefan Thurner
- Section for Science of Complex Systems, Center for Medical Statistics, Informatics, and Intelligent Systems (CeMSIIS), Medical University of Vienna, Vienna, Austria.,Complexity Science Hub Vienna, Vienna, Austria.,Santa Fe Institute, Santa Fe, NM, United States.,Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
| | - Peter Klimek
- Section for Science of Complex Systems, Center for Medical Statistics, Informatics, and Intelligent Systems (CeMSIIS), Medical University of Vienna, Vienna, Austria.,Complexity Science Hub Vienna, Vienna, Austria
| | - Alexandra Kautzky-Willer
- Clinical Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.,Gender Institute, Gars am Kamp, Austria
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16
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Kumar GA, Chattopadhyay A. Membrane cholesterol regulates endocytosis and trafficking of the serotonin 1A receptor: Insights from acute cholesterol depletion. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158882. [PMID: 33429076 DOI: 10.1016/j.bbalip.2021.158882] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 12/24/2020] [Accepted: 01/06/2021] [Indexed: 12/12/2022]
Abstract
Endocytosis and intracellular trafficking constitute important regulatory features associated with G protein-coupled receptor (GPCR) function. GPCR endocytosis involves several remodeling events at the plasma membrane orchestrated by a concerted interplay of a large number of proteins and membrane lipids. Although considerable literature exists on the protein framework underlying GPCR endocytosis, the role of membrane lipids in this process remains largely unexplored. In order to explore the role of membrane cholesterol (an essential and important lipid in higher eukaryotes) in GPCR endocytosis, we monitored the effect of acute cholesterol depletion using methyl-β-cyclodextrin (MβCD) on endocytosis and intracellular trafficking of the serotonin1A receptor, an important neurotransmitter GPCR. Our results show that the serotonin1A receptor exhibits agonist-induced clathrin-mediated endocytosis with a concentration-dependent inhibition in internalization with increasing concentrations of MβCD, which was restored upon cholesterol replenishment. Interestingly, subsequent to internalization under these conditions, serotonin1A receptors were re-routed toward lysosomal degradation, instead of endosomal recycling observed under normal conditions, thereby implicating membrane cholesterol in modulation of intracellular trafficking of the receptor. This raises the possibility of a novel cholesterol-dependent role of intracellular sorting proteins in GPCR trafficking. These results differ from our previous observations on the endocytosis of the serotonin1A receptor upon statin-induced chronic cholesterol depletion, in terms of endocytic pathway. We conclude that analysis of complex cellular trafficking events such as GPCR endocytosis under acute and chronic cholesterol depletion conditions should be carried out with caution due to fundamental differences underlying these processes.
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Affiliation(s)
- G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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17
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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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18
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Structural Stringency and Optimal Nature of Cholesterol Requirement in the Function of the Serotonin1A Receptor. J Membr Biol 2020; 253:445-457. [DOI: 10.1007/s00232-020-00138-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/04/2020] [Indexed: 12/11/2022]
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19
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Sarkar P, Rao BD, Chattopadhyay A. Cell Cycle Dependent Modulation of Membrane Dipole Potential and Neurotransmitter Receptor Activity: Role of Membrane Cholesterol. ACS Chem Neurosci 2020; 11:2890-2899. [PMID: 32786305 DOI: 10.1021/acschemneuro.0c00499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The cell cycle is a sequential multistep process essential for growth and proliferation of cells that make up multicellular organisms. A number of nuclear and cytoplasmic proteins are known to modulate the cell cycle. Yet, the role of lipids, membrane organization, and physical properties in cell cycle progression remains largely elusive. Membrane dipole potential is an important physicochemical property and originates due to the electrostatic potential difference within the membrane because of nonrandom arrangement of amphiphile dipoles and water molecules at the membrane interface. In this work, we explored the modulation of membrane dipole potential in various stages of the cell cycle in CHO-K1 cells. Our results show that membrane dipole potential is highest in the G1 phase relative to S and G2/M phases. This was accompanied by regulation of membrane cholesterol content in the cell cycle. The highest cholesterol content was found in the G1 phase with a considerable reduction in cholesterol in S and G2/M phases. Interestingly, we noted a similarity in the dependence of membrane dipole potential and cholesterol with progress of the cell cycle. In addition, we observed an increase in neutral lipid (which contains esterified cholesterol) content as cells progressed from the G1 to G2/M phase via the S phase of the cell cycle. Importantly, we further observed a cell cycle dependent reduction in ligand binding activity of serotonin1A receptors expressed in CHO-K1 cells. To the best of our knowledge, these results constitute the first report of cell cycle dependent modulation of membrane dipole potential and activity of a neurotransmitter receptor belonging to the G protein-coupled receptor family. We envision that understanding the basis of cell cycle events from a biophysical perspective would result in a deeper appreciation of the cell cycle and its regulation in relation to cellular function.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Bhagyashree D. Rao
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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20
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Shrivastava S, Paila YD, Kombrabail M, Krishnamoorthy G, Chattopadhyay A. Role of Cholesterol and Its Immediate Biosynthetic Precursors in Membrane Dynamics and Heterogeneity: Implications for Health and Disease. J Phys Chem B 2020; 124:6312-6320. [DOI: 10.1021/acs.jpcb.0c04338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Sandeep Shrivastava
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Yamuna Devi Paila
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Mamata Kombrabail
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
| | - G. Krishnamoorthy
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
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21
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Rao BD, Sarkar P, Chattopadhyay A. Selectivity in agonist and antagonist binding to Serotonin 1A receptors via G-protein coupling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183265. [PMID: 32156647 DOI: 10.1016/j.bbamem.2020.183265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 12/16/2022]
Abstract
G protein-coupled receptors (GPCRs) constitute the largest superfamily of membrane proteins in higher eukaryotes, and facilitate information transfer from the extracellular environment to the cellular interior upon activation by ligands. Their role in diverse signaling processes makes them an attractive choice as drug targets. GPCRs are coupled to heterotrimeric G-proteins which represent an important interface through which signal transduction occurs across the plasma membrane upon activation by ligands. To obtain further insight into the molecular details of interaction of G-proteins with GPCRs, in this work, we explored the selectivity of binding of specific agonists and antagonists to the serotonin1A receptor under conditions of progressive G-protein inactivation. The serotonin1A receptor is an important neurotransmitter receptor belonging to the GPCR family and is a popular drug target. By use of a number of agents to inactivate G-proteins, we show here that the serotonin1A receptor displays differential discrimination between agonist and antagonist binding. Our results show a reduction in binding sites of the receptor upon treatment with G-protein inactivating agents. In addition, G-protein coupling efficiency was enhanced when G-proteins were inactivated using urea and alkaline pH. We envision that our results could be useful in achieving multiple signaling states of the receptor by fine tuning the conditions of G-protein inactivation and in structural biology of GPCRs bound to specific ligands.
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Affiliation(s)
- Bhagyashree D Rao
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research, Ghaziabad 201 002, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research, Ghaziabad 201 002, India.
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22
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Membrane cholesterol oxidation downregulates atrial β-adrenergic responses in ROS-dependent manner. Cell Signal 2020; 67:109503. [DOI: 10.1016/j.cellsig.2019.109503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/15/2019] [Accepted: 12/15/2019] [Indexed: 01/06/2023]
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23
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Sarkar P, Chattopadhyay A. Cholesterol interaction motifs in G protein-coupled receptors: Slippery hot spots? WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2020; 12:e1481. [PMID: 32032482 DOI: 10.1002/wsbm.1481] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/28/2019] [Accepted: 01/09/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) are cell membrane associated signaling hubs that orchestrate a multitude of cellular functions upon binding to a diverse variety of extracellular ligands. Since GPCRs are integral membrane proteins with seven-transmembrane domain architecture, their function, organization and dynamics are intimately regulated by membrane lipids, such as cholesterol. Cholesterol is an extensively studied lipids in terms of its effects on GPCR structure and function. One of the possible mechanisms underlying modulation of GPCR function by cholesterol is via specific interaction of GPCRs with membrane cholesterol. These interactions of GPCRs with membrane cholesterol are often attributed to structural features of GPCRs that could facilitate their preferential association with cholesterol. In this backdrop, cholesterol interaction motifs represent putative interaction sites on GPCRs that could facilitate cholesterol-sensitive function of these receptors. In this review, we provide an overview of cholesterol interaction motifs found in GPCRs, which have been identified through a combination of crystallography, bioinformatics analysis, and functional studies. In addition, we will highlight, using specific examples, why mere presence of a cholesterol interaction motif at a given site may not directly implicate its role in interaction with membrane cholesterol. We therefore believe that experimental approaches, followed by functional analysis of cholesterol sensitivity of GPCRs, would provide a better understanding of the role played by these motifs in cholesterol-sensitive function. We envision that a comprehensive knowledge of cholesterol interaction sites in GPCRs would allow us to develop a better understanding of GPCR structure-function paradigm, and could be useful in future therapeutics. This article is categorized under: Models of Systems Properties and Processes > Mechanistic Models Analytical and Computational Methods > Computational Methods Laboratory Methods and Technologies > Macromolecular Interactions, Methods.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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24
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Kumar GA, Chattopadhyay A. Statin-Induced Chronic Cholesterol Depletion Switches GPCR Endocytosis and Trafficking: Insights from the Serotonin 1A Receptor. ACS Chem Neurosci 2020; 11:453-465. [PMID: 31880914 DOI: 10.1021/acschemneuro.9b00659] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Endocytosis is a key regulatory mechanism adopted by G protein-coupled receptors (GPCRs) to modulate downstream signaling responses within a stringent spatiotemporal regime. Although the role of membrane lipids has been extensively studied in the context of the function, organization, and dynamics of GPCRs, their role in receptor endocytosis remains largely unexplored. Cholesterol, the predominant sterol in higher eukaryotes, plays a crucial role in maintaining the structure and organization of cell membranes and is involved in essential cellular processes in health and disease. The serotonin1A receptor is a representative GPCR involved in neuronal development and in neuropsychiatric disorders such as anxiety and depression. We recently combined quantitative flow cytometric and confocal microscopic approaches to demonstrate that the serotonin1A receptor undergoes clathrin-mediated endocytosis upon agonist stimulation and subsequently traffics along the endosomal recycling pathway. In this work, we show that statin-induced chronic cholesterol depletion switches the endocytic pathway of the serotonin1A receptor from clathrin- to caveolin-mediated endocytosis. Interestingly, under these conditions, a significant proportion of endocytosed receptors is rerouted toward lysosomal degradation. To the best of our knowledge, these results constitute one of the first comprehensive reports on the role of membrane cholesterol in GPCR endocytosis and trafficking. These results are significant in our overall understanding of the modulatory effects of membrane lipids on GPCR endocytosis and trafficking and could provide novel insight in developing therapeutic interventions against neuropsychiatric disorders such as depression.
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Affiliation(s)
- G. Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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25
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Role of cholesterol-mediated effects in GPCR heterodimers. Chem Phys Lipids 2019; 227:104852. [PMID: 31866438 DOI: 10.1016/j.chemphyslip.2019.104852] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 12/16/2019] [Accepted: 12/16/2019] [Indexed: 12/19/2022]
Abstract
G protein-coupled receptors (GPCRs) are transmembrane receptors that mediate a large number of cellular responses. The organization of GPCRs into dimers and higher-order oligomers is known to allow a larger repertoire of downstream signaling events. In this context, a crosstalk between the adenosine and dopamine receptors has been reported, indicating the presence of heterodimers that are functionally relevant. In this paper, we explored the effect of membrane cholesterol on the adenosine2A (A2A) and dopamine D3 (D3) receptors using coarse-grain molecular dynamics simulations. We analyzed cholesterol interaction sites on the A2A receptor and were able to reproduce the sites indicated by crystallography and previous atomistic simulations. We predict novel cholesterol interaction sites on the D3 receptor that could be important in the reported cholesterol sensitivity in receptor function. Further, we analyzed the formation of heterodimers between the two receptors. Our results suggest that membrane cholesterol modulates the relative population of several co-existing heterodimer conformations. Both direct receptor-cholesterol interaction and indirect membrane effects contribute toward the modulation of heterodimer conformations. These results constitute one of the first examples of modulation of GPCR hetero-dimerization by membrane cholesterol, and could prove to be useful in designing better therapeutic strategies.
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26
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A Perspective: Active Role of Lipids in Neurotransmitter Dynamics. Mol Neurobiol 2019; 57:910-925. [PMID: 31595461 PMCID: PMC7031182 DOI: 10.1007/s12035-019-01775-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/01/2019] [Indexed: 12/30/2022]
Abstract
Synaptic neurotransmission is generally considered as a function of membrane-embedded receptors and ion channels in response to the neurotransmitter (NT) release and binding. This perspective aims to widen the protein-centric view by including another vital component—the synaptic membrane—in the discussion. A vast set of atomistic molecular dynamics simulations and biophysical experiments indicate that NTs are divided into membrane-binding and membrane-nonbinding categories. The binary choice takes place at the water-membrane interface and follows closely the positioning of the receptors’ binding sites in relation to the membrane. Accordingly, when a lipophilic NT is on route to a membrane-buried binding site, it adheres on the membrane and, then, travels along its plane towards the receptor. In contrast, lipophobic NTs, which are destined to bind into receptors with extracellular binding sites, prefer the water phase. This membrane-based sorting splits the neurotransmission into membrane-independent and membrane-dependent mechanisms and should make the NT binding into the receptors more efficient than random diffusion would allow. The potential implications and notable exceptions to the mechanisms are discussed here. Importantly, maintaining specific membrane lipid compositions (MLCs) at the synapses, especially regarding anionic lipids, affect the level of NT-membrane association. These effects provide a plausible link between the MLC imbalances and neurological diseases such as depression or Parkinson’s disease. Moreover, the membrane plays a vital role in other phases of the NT life cycle, including storage and release from the synaptic vesicles, transport from the synaptic cleft, as well as their synthesis and degradation.
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27
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Pal S, Chattopadhyay A. Extramembranous Regions in G Protein-Coupled Receptors: Cinderella in Receptor Biology? J Membr Biol 2019; 252:483-497. [DOI: 10.1007/s00232-019-00092-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
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28
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Kumar GA, Sarkar P, Jafurulla M, Singh SP, Srinivas G, Pande G, Chattopadhyay A. Exploring Endocytosis and Intracellular Trafficking of the Human Serotonin1A Receptor. Biochemistry 2019; 58:2628-2641. [DOI: 10.1021/acs.biochem.9b00033] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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
| | - 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, Bangalore 560 065, India
| | - Gunda Srinivas
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Gopal Pande
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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29
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Fatakia SN, Sarkar P, Chattopadhyay A. A collage of cholesterol interaction motifs in the serotonin 1A receptor: An evolutionary implication for differential cholesterol interaction. Chem Phys Lipids 2019; 221:184-192. [PMID: 30822391 DOI: 10.1016/j.chemphyslip.2019.02.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 02/25/2019] [Accepted: 02/25/2019] [Indexed: 12/22/2022]
Abstract
The serotonin1A receptor is a representative member of the G protein-coupled receptor (GPCR) superfamily and acts as an important drug target. In our previous work, we comprehensively demonstrated that membrane cholesterol is necessary in the organization, dynamics and function of the serotonin1A receptor. In this context, analysis of high-resolution GPCR crystal structures in general and in silico studies of the serotonin1A receptor in particular, have suggested the presence of cholesterol interaction sites (hotspots) in various regions of the receptor. In this work, we have identified an evolutionarily conserved collage of four categories of cholesterol interaction motifs associated with transmembrane helix V and the adjacent intracellular loop 3 fragment of the vertebrate serotonin1A receptor. This collage of motifs represents a total of twenty diverse context-dependent cholesterol interaction configurations. We envision that the gamut of cholesterol interaction sites, characterized by sequence plasticity in cholesterol interaction, could be relevant in receptor-cholesterol interaction in membranes of varying cholesterol content and organization, as found in diverse cell types. We conclude that an evolutionarily conserved mechanism of GPCR-cholesterol interaction allows the serotonin1A receptor to adapt to diverse membrane cholesterol levels during natural evolution.
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Affiliation(s)
- Sarosh N Fatakia
- 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
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30
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Sarkar P, Chattopadhyay A. Exploring membrane organization at varying spatiotemporal resolutions utilizing fluorescence-based approaches: implications in membrane biology. Phys Chem Chem Phys 2019; 21:11554-11563. [DOI: 10.1039/c9cp02087j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Representative experimental approaches based on dynamic fluorescence microscopy to analyze organization and dynamics of membrane lipids and proteins.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology
- Hyderabad 500 007
- India
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31
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A Critical Analysis of Molecular Mechanisms Underlying Membrane Cholesterol Sensitivity of GPCRs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:21-52. [PMID: 30649754 DOI: 10.1007/978-3-030-04278-3_2] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
G protein-coupled receptors (GPCRs) are the largest and a diverse family of proteins involved in signal transduction across biological membranes. GPCRs mediate a wide range of physiological processes and have emerged as major targets for the development of novel drug candidates in all clinical areas. Since GPCRs are integral membrane proteins, regulation of their organization, dynamics, and function by membrane lipids, in particular membrane cholesterol, has emerged as an exciting area of research. Cholesterol sensitivity of GPCRs could be due to direct interaction of cholesterol with the receptor (specific effect). Alternately, GPCR function could be influenced by the effect of cholesterol on membrane physical properties (general effect). In this review, we critically analyze the specific and general mechanisms of the modulation of GPCR function by membrane cholesterol, taking examples from representative GPCRs. While evidence for both the proposed mechanisms exists, there appears to be no clear-cut distinction between these two mechanisms, and a combination of these mechanisms cannot be ruled out in many cases. We conclude that classifying the mechanism underlying cholesterol sensitivity of GPCR function merely into these two mutually exclusive classes could be somewhat arbitrary. A more holistic approach could be suitable for analyzing GPCR-cholesterol interaction.
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32
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Bukiya AN, Blank PS, Rosenhouse-Dantsker A. Cholesterol intake and statin use regulate neuronal G protein-gated inwardly rectifying potassium channels. J Lipid Res 2018; 60:19-29. [PMID: 30420402 DOI: 10.1194/jlr.m081240] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/10/2018] [Indexed: 12/31/2022] Open
Abstract
Cholesterol, a critical component of the cellular plasma membrane, is essential for normal neuronal function. Cholesterol content is highest in the brain, where most cholesterol is synthesized de novo; HMG-CoA reductase controls the synthesis rate. Despite strict control, elevated blood cholesterol levels are common and are associated with various neurological disorders. G protein-gated inwardly rectifying potassium (GIRK) channels mediate the actions of inhibitory brain neurotransmitters. Loss of GIRK function enhances neuron excitability; gain of function reduces neuronal activity. However, the effect of dietary cholesterol or HMG-CoA reductase inhibition (i.e., statin therapy) on GIRK function remains unknown. Using a rat model, we compared the effects of a high-cholesterol versus normal diet both with and without atorvastatin, a widely prescribed HMG-CoA reductase inhibitor, on neuronal GIRK currents. The high-cholesterol diet increased hippocampal CA1 region cholesterol levels and correspondingly increased neuronal GIRK currents. Both phenomena were reversed by cholesterol depletion in vitro. Atorvastatin countered the high-cholesterol diet effects on neuronal cholesterol content and GIRK currents; these effects were reversed by cholesterol enrichment in vitro. Our findings suggest that high-cholesterol diet and atorvastatin therapy affect ion channel function in the brain by modulating neuronal cholesterol levels.
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Affiliation(s)
- Anna N Bukiya
- Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163
| | - Paul S Blank
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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Viswanathan G, Jafurulla M, Kumar GA, Raghunand TR, Chattopadhyay A. Macrophage sphingolipids are essential for the entry of mycobacteria. Chem Phys Lipids 2018. [DOI: 10.1016/j.chemphyslip.2018.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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34
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Constrained dynamics of the sole tryptophan in the third intracellular loop of the serotonin 1A receptor. Biophys Chem 2018; 240:34-41. [PMID: 29885563 DOI: 10.1016/j.bpc.2018.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 05/24/2018] [Accepted: 05/27/2018] [Indexed: 12/19/2022]
Abstract
G protein-coupled receptors (GPCRs) are major signaling proteins in eukaryotic cells and are important drug targets. In spite of their role in GPCR function, the extramembranous regions of GPCRs are relatively less appreciated. The third intracellular loop (ICL3), which connects transmembrane helices V and VI, is important in this context since its crucial role in signaling has been documented for a number of GPCRs. Unfortunately, the structure of this loop is generally not visualized in x-ray crystallographic studies since this flexible loop is either stabilized using a monoclonal antibody or replaced with lysozyme. In this work, we expressed and purified the ICL3 region of the serotonin1A receptor and monitored its motional restriction and organization utilizing red edge excitation shift (REES) of its sole tryptophan and circular dichroism (CD) spectroscopy. Our results show that the tryptophan in ICL3 exhibits REES of 4 nm, implying that it is localized in a restricted microenvironment. These results are further supported by wavelength-selective changes in fluorescence anisotropy and lifetime. This constrained dynamics was relaxed upon denaturation of the peptide, thereby suggesting the involvement of the peptide secondary structure in the observed motional restriction, as evident from CD spectroscopy and apparent rotational correlation time. To the best of our knowledge, these results constitute one of the first measurements of motional constraint in the ICL3 region of GPCRs. Our results are relevant in the context of the reported intrinsically disordered nature of ICL3 and its role in providing functional diversity to GPCRs due to conformational plasticity.
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Sengupta D, Prasanna X, Mohole M, Chattopadhyay A. Exploring GPCR–Lipid Interactions by Molecular Dynamics Simulations: Excitements, Challenges, and the Way Forward. J Phys Chem B 2018; 122:5727-5737. [DOI: 10.1021/acs.jpcb.8b01657] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Durba Sengupta
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India
- Academy of Scientific and Innovative Research, Sector 19, Kamla Nehru Nagar, Ghaziabad 201 002, India
| | - Xavier Prasanna
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India
| | - Madhura Mohole
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India
- Academy of Scientific and Innovative Research, Sector 19, Kamla Nehru Nagar, Ghaziabad 201 002, India
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Mohole M, Prasanna X, Sengupta D, Chattopadhyay A. Molecular Signatures of Cholesterol Interaction with Serotonin Receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1112:151-160. [DOI: 10.1007/978-981-13-3065-0_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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37
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Chakraborty H, Jafurulla M, Clayton AHA, Chattopadhyay A. Exploring oligomeric state of the serotonin1A receptor utilizing photobleaching image correlation spectroscopy: implications for receptor function. Faraday Discuss 2018; 207:409-421. [DOI: 10.1039/c7fd00192d] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Photobleaching image correlation spectroscopy (pbICS) reveals that membrane cholesterol modulates the oligomeric state of the serotonin1A receptor.
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Affiliation(s)
- Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology
- Hyderabad 500 007
- India
- School of Chemistry
- Sambalpur University
| | - Md. Jafurulla
- CSIR-Centre for Cellular and Molecular Biology
- Hyderabad 500 007
- India
| | - Andrew H. A. Clayton
- Centre for Microphotonics
- Faculty of Science
- Engineering and Technology
- Swinburne University of Technology
- Hawthorn
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Shrivastava S, Jafurulla M, Tiwari S, Chattopadhyay A. Identification of Sphingolipid-binding Motif in G Protein-coupled Receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1112:141-149. [DOI: 10.1007/978-981-13-3065-0_10] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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39
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Solubilization of the serotonin 1A receptor monitored utilizing membrane dipole potential. Chem Phys Lipids 2017; 209:54-60. [DOI: 10.1016/j.chemphyslip.2017.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 12/31/2022]
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40
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Gutierrez MG, Mansfield KS, Malmstadt N. The Functional Activity of the Human Serotonin 5-HT1A Receptor Is Controlled by Lipid Bilayer Composition. Biophys J 2017; 110:2486-2495. [PMID: 27276266 DOI: 10.1016/j.bpj.2016.04.042] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/22/2016] [Indexed: 01/08/2023] Open
Abstract
Although the properties of the cell plasma membrane lipid bilayer are broadly understood to affect integral membrane proteins, details of these interactions are poorly understood. This is particularly the case for the large family of G protein-coupled receptors (GPCRs). Here, we examine the lipid dependence of the human serotonin 5-HT1A receptor, a GPCR that is central to neuronal function. We incorporate the protein in synthetic bilayers of controlled composition together with a fluorescent reporting system that detects GPCR-catalyzed activation of G protein to measure receptor-catalyzed oligonucleotide exchange. Our results show that increased membrane order induced by sterols and sphingomyelin increases receptor-catalyzed oligonucleotide exchange. Increasing membrane elastic curvature stress also increases this exchange. These results reveal the broad dependence that the 5-HT1A receptor has on plasma membrane properties, demonstrating that membrane lipid composition is a biochemical control parameter and highlighting the possibility that compositional changes related to aging, diet, or disease could impact cell signaling functions.
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Affiliation(s)
- M Gertrude Gutierrez
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California
| | - Kylee S Mansfield
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California
| | - Noah Malmstadt
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California.
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Differential Membrane Dipolar Orientation Induced by Acute and Chronic Cholesterol Depletion. Sci Rep 2017; 7:4484. [PMID: 28667339 PMCID: PMC5493612 DOI: 10.1038/s41598-017-04769-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 05/22/2017] [Indexed: 02/02/2023] Open
Abstract
Cholesterol plays a crucial role in cell membrane organization, dynamics and function. Depletion of cholesterol represents a popular approach to explore cholesterol-sensitivity of membrane proteins. An emerging body of literature shows that the consequence of membrane cholesterol depletion often depends on the actual process (acute or chronic), although the molecular mechanism underlying the difference is not clear. Acute depletion, using cyclodextrin-type carriers, is faster relative to chronic depletion, in which inhibitors of cholesterol biosynthesis are used. With the overall goal of addressing molecular differences underlying these processes, we monitored membrane dipole potential under conditions of acute and chronic cholesterol depletion in CHO-K1 cells, using a voltage-sensitive fluorescent dye in dual wavelength ratiometric mode. Our results show that the observed membrane dipole potential exhibits difference under acute and chronic cholesterol depletion conditions, even when cholesterol content was identical. To the best of our knowledge, these results provide, for the first time, molecular insight highlighting differences in dipolar reorganization in these processes. A comprehensive understanding of processes in which membrane cholesterol gets modulated would provide novel insight in its interaction with membrane proteins and receptors, thereby allowing us to understand the role of cholesterol in cellular physiology associated with health and disease.
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42
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Membrane cholesterol oxidation in live cells enhances the function of serotonin 1A receptors. Chem Phys Lipids 2017; 203:71-77. [DOI: 10.1016/j.chemphyslip.2017.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 01/15/2017] [Accepted: 01/15/2017] [Indexed: 12/14/2022]
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43
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Jafurulla M, Chattopadhyay A. Structural Stringency of Cholesterol for Membrane Protein Function Utilizing Stereoisomers as Novel Tools: A Review. Methods Mol Biol 2017; 1583:21-39. [PMID: 28205164 DOI: 10.1007/978-1-4939-6875-6_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Cholesterol is an important lipid in the context of membrane protein function. The function of a number of membrane proteins, including G protein-coupled receptors (GPCRs) and ion channels, has been shown to be dependent on membrane cholesterol. However, the molecular mechanism underlying such regulation is still being explored. In some cases, specific interaction between cholesterol and the protein has been implicated. In other cases, the effect of cholesterol on the membrane properties has been attributed for the regulation of protein function. In this article, we have provided an overview of experimental approaches that are useful for determining the degree of structural stringency of cholesterol for membrane protein function. In the process, we have highlighted the role of immediate precursors in cholesterol biosynthetic pathway in the function of membrane proteins. Special emphasis has been given to the application of stereoisomers of cholesterol in deciphering the structural stringency required for regulation of membrane protein function. A comprehensive examination of these processes would help in understanding the molecular basis of cholesterol regulation of membrane proteins in subtle details.
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Affiliation(s)
- Md Jafurulla
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
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44
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Marino KA, Prada-Gracia D, Provasi D, Filizola M. Impact of Lipid Composition and Receptor Conformation on the Spatio-temporal Organization of μ-Opioid Receptors in a Multi-component Plasma Membrane Model. PLoS Comput Biol 2016; 12:e1005240. [PMID: 27959924 PMCID: PMC5154498 DOI: 10.1371/journal.pcbi.1005240] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 11/07/2016] [Indexed: 11/21/2022] Open
Abstract
The lipid composition of cell membranes has increasingly been recognized as playing an important role in the function of various membrane proteins, including G Protein-Coupled Receptors (GPCRs). For instance, experimental and computational evidence has pointed to lipids influencing receptor oligomerization directly, by physically interacting with the receptor, and/or indirectly, by altering the bulk properties of the membrane. While the exact role of oligomerization in the function of class A GPCRs such as the μ-opioid receptor (MOR) is still unclear, insight as to how these receptors oligomerize and the relevance of the lipid environment to this phenomenon is crucial to our understanding of receptor function. To examine the effect of lipids and different MOR conformations on receptor oligomerization we carried out extensive coarse-grained molecular dynamics simulations of crystal structures of inactive and/or activated MOR embedded in an idealized mammalian plasma membrane composed of 63 lipid types asymmetrically distributed across the two leaflets. The results of these simulations point, for the first time, to specific direct and indirect effects of the lipids, as well as the receptor conformation, on the spatio-temporal organization of MOR in the plasma membrane. While sphingomyelin-rich, high-order lipid regions near certain transmembrane (TM) helices of MOR induce an effective long-range attractive force on individual protomers, both long-range lipid order and interface formation are found to be conformation dependent, with a larger number of different interfaces formed by inactive MOR compared to active MOR. The μ-opioid receptor (MOR) is an important pharmaceutical target in the treatment of pain. In order to develop novel pain therapies, devoid of the serious side-effects of present opioid analgesics, we need to understand the fundamentals of how MOR works on the molecular level. While some studies suggest that oligomers of MOR could play a role in signaling, how MOR forms dimers, which interfaces form, and the exact role of oligomers in MOR function remain unclear. While research has shown that the membrane environment can affect membrane protein function, most previous computational work to study oligomerization has been performed in a very simple membrane. Here, we use molecular dynamics simulations of MOR in a heterogeneous plasma membrane model (comprising 63 lipid types) to investigate how the presence of the protein modulates its lipid environment, affecting species distribution and sculpting characteristic order and thickness profiles around the receptors. Such modulations, in turn, induce long-range interactions between the proteins and favor the formation of specific dimeric conformations.
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Affiliation(s)
- Kristen A. Marino
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, United States of America
| | - Diego Prada-Gracia
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, United States of America
| | - Davide Provasi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, United States of America
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, United States of America
- * E-mail:
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45
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Effect of local anesthetics on serotonin1A receptor function. Chem Phys Lipids 2016; 201:41-49. [DOI: 10.1016/j.chemphyslip.2016.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/27/2016] [Accepted: 11/01/2016] [Indexed: 01/05/2023]
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46
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Gendle MH. The potential behavioral and economic impacts of widespread HMG-CoA reductase inhibitor (statin) use. Med Hypotheses 2016; 97:54-58. [DOI: 10.1016/j.mehy.2016.10.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 10/06/2016] [Accepted: 10/22/2016] [Indexed: 01/21/2023]
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47
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Prasanna X, Jafurulla M, Sengupta D, Chattopadhyay A. The ganglioside GM1 interacts with the serotonin 1A receptor via the sphingolipid binding domain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2818-2826. [DOI: 10.1016/j.bbamem.2016.08.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 07/18/2016] [Accepted: 08/18/2016] [Indexed: 12/24/2022]
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48
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Jafurulla M, Bandari S, Pucadyil TJ, Chattopadhyay A. Sphingolipids modulate the function of human serotonin 1A receptors: Insights from sphingolipid-deficient cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:598-604. [PMID: 27984018 DOI: 10.1016/j.bbamem.2016.10.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 10/16/2016] [Accepted: 10/25/2016] [Indexed: 11/18/2022]
Abstract
Sphingolipids are essential components of eukaryotic cell membranes and are known to modulate a variety of cellular functions. It is becoming increasingly clear that membrane lipids play a crucial role in modulating the function of integral membrane proteins such as G protein-coupled receptors (GPCRs). In this work, we utilized LY-B cells, that are sphingolipid-auxotrophic mutants defective in sphingolipid biosynthesis, to monitor the role of cellular sphingolipids in the function of an important neurotransmitter receptor, the serotonin1A receptor. Serotonin1A receptors belong to the family of GPCRs and are implicated in behavior, development and cognition. Our results show that specific ligand binding and G-protein coupling of the serotonin1A receptor exhibit significant enhancement under sphingolipid-depleted conditions, which reversed to control levels upon replenishment of cellular sphingolipids. In view of the reported role of sphingolipids in neuronal metabolism and pathogenesis of several neuropsychiatric disorders, exploring the role of serotonin1A receptors under conditions of defective sphingolipid metabolism assumes relevance, and could contribute to our overall understanding of such neuropsychiatric disorders. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Md Jafurulla
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Suman Bandari
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Thomas J Pucadyil
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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49
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Cholesterol-dependent Conformational Plasticity in GPCR Dimers. Sci Rep 2016; 6:31858. [PMID: 27535203 PMCID: PMC4989139 DOI: 10.1038/srep31858] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 07/28/2016] [Indexed: 12/04/2022] Open
Abstract
The organization and function of the serotonin1A receptor, an important member of the GPCR family, have been shown to be cholesterol-dependent, although the molecular mechanism is not clear. We performed a comprehensive structural and dynamic analysis of dimerization of the serotonin1A receptor by coarse-grain molecular dynamics simulations totaling 3.6 ms to explore the molecular details of its cholesterol-dependent association. A major finding is that the plasticity and flexibility of the receptor dimers increase with increased cholesterol concentration. In particular, a dimer interface formed by transmembrane helices I-I was found to be sensitive to cholesterol. The modulation of dimer interface appears to arise from a combination of direct cholesterol occupancy and indirect membrane effects. Interestingly, the presence of cholesterol at the dimer interface is correlated with increased dimer plasticity and flexibility. These results represent an important step in characterizing the molecular interactions in GPCR organization with potential relevance to therapeutic interventions.
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50
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Patra SM, Chakraborty S, Shahane G, Prasanna X, Sengupta D, Maiti PK, Chattopadhyay A. Differential dynamics of the serotonin1A receptor in membrane bilayers of varying cholesterol content revealed by all atom molecular dynamics simulation. Mol Membr Biol 2016; 32:127-37. [PMID: 26508556 DOI: 10.3109/09687688.2015.1096971] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The serotonin1A receptor belongs to the superfamily of G protein-coupled receptors (GPCRs) and is a potential drug target in neuropsychiatric disorders. The receptor has been shown to require membrane cholesterol for its organization, dynamics and function. Although recent work suggests a close interaction of cholesterol with the receptor, the structural integrity of the serotonin1A receptor in the presence of cholesterol has not been explored. In this work, we have carried out all atom molecular dynamics simulations, totaling to 3 μs, to analyze the effect of cholesterol on the structure and dynamics of the serotonin1A receptor. Our results show that the presence of physiologically relevant concentration of membrane cholesterol alters conformational dynamics of the serotonin1A receptor and, on an average lowers conformational fluctuations. Our results show that, in general, transmembrane helix VII is most affected by the absence of membrane cholesterol. These results are in overall agreement with experimental data showing enhancement of GPCR stability in the presence of membrane cholesterol. Our results constitute a molecular level understanding of GPCR-cholesterol interaction, and represent an important step in our overall understanding of GPCR function in health and disease.
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Affiliation(s)
- Swarna M Patra
- a Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science , Bangalore , India .,b Department of Chemistry , RV College of Engineering , Bangalore , India
| | - Sudip Chakraborty
- a Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science , Bangalore , India
| | - Ganesh Shahane
- c CSIR-National Chemical Laboratory , Pune , India , and
| | | | - Durba Sengupta
- c CSIR-National Chemical Laboratory , Pune , India , and
| | - Prabal K Maiti
- a Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science , Bangalore , India
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