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Guan L, Tan J, Qi B, Chen Y, Cao M, Zhang Q, Zou Y. Effects of an external static EF on the conformational transition of 5-HT1A receptor: A molecular dynamics simulation study. Biophys Chem 2024; 312:107283. [PMID: 38941873 DOI: 10.1016/j.bpc.2024.107283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 06/16/2024] [Indexed: 06/30/2024]
Abstract
The serotonin receptor subtype 1A (5-HT1AR), one of the G-protein-coupled receptor (GPCR) family, has been implicated in several neurological conditions. Understanding the activation and inactivation mechanism of 5-HT1AR at the molecular level is critical for discovering novel therapeutics in many diseases. Recently there has been a growing appreciation for the role of external electric fields (EFs) in influencing the structure and activity of biomolecules. In this study, we used molecular dynamics (MD) simulations to examine conformational features of active states of 5-HT1AR and investigate the effect of an external static EF with 0.02 V/nm applied on the active state of 5-HT1AR. Our results showed that the active state of 5-HT1AR maintained the native structure, while the EF led to structural modifications in 5-HT1AR, particularly inducing the inward movement of transmembrane helix 6 (TM6). Furthermore, it disturbed the conformational switches associated with activation in the CWxP, DRY, PIF, and NPxxY motifs, consequently predisposing an inclination towards the inactive-like conformation. We also found that the EF led to an overall increase in the dipole moment of 5-HT1AR, encompassing TM6 and pivotal amino acids. The analyses of conformational properties of TM6 showed that the changed secondary structure and decreased solvent exposure occurred upon the EF condition. The interaction of 5-HT1AR with the membrane lipid bilayer was also altered under the EF. Our findings reveal the molecular mechanism underlying the transition of 5-HT1AR conformation induced by external EFs, which offer potential novel insights into the prospect of employing structure-based EF applications for GPCRs.
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Affiliation(s)
- Lulu Guan
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Jingwang Tan
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Bote Qi
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Yukang Chen
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Meng Cao
- Department of Physical Education, College of Sport, Shenzhen University, 3688 Nanhai Road, Shenzhen, Guangdong 518061, PR China
| | - Qingwen Zhang
- College of Physical Education, Shanghai University of Sport, 399 Changhai Road, Shanghai 200438, PR China
| | - Yu Zou
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China.
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2
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Shubhrasmita Sahu S, Sarkar P, Chattopadhyay A. Quantitation of F-actin in cytoskeletal reorganization: Context, methodology and implications. Methods 2024; 230:44-58. [PMID: 39074540 DOI: 10.1016/j.ymeth.2024.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 07/08/2024] [Accepted: 07/17/2024] [Indexed: 07/31/2024] Open
Abstract
The actin cytoskeleton is involved in a large number of cellular signaling events in addition to providing structural integrity to the cell. Actin polymerization is a key event during cellular signaling. Although the role of actin cytoskeleton in cellular processes such as trafficking and motility has been extensively studied, the reorganization of the actin cytoskeleton upon signaling has been rarely explored due to lack of suitable assays. Keeping in mind this lacuna, we developed a confocal microscopy based approach that relies on high magnification imaging of cellular F-actin, followed by image reconstruction using commercially available software. In this review, we discuss the context and relevance of actin quantitation, followed by a detailed hands-on approach of the methodology involved with specific points on troubleshooting and useful precautions. In the latter part of the review, we elucidate the method by discussing applications of actin quantitation from our work in several important problems in contemporary membrane biology ranging from pathogen entry into host cells, to GPCR signaling and membrane-cytoskeleton interaction. We envision that future discovery of cell-permeable novel fluorescent probes, in combination with genetically encoded actin-binding reporters, would allow real-time visualization of actin cytoskeleton dynamics to gain deeper insights into active cellular processes in health and disease.
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Affiliation(s)
- Subhashree Shubhrasmita Sahu
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Department of Biochemistry, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
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3
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Akyuz E, Arulsamy A, Aslan FS, Sarisözen B, Guney B, Hekimoglu A, Yilmaz BN, Retinasamy T, Shaikh MF. An Expanded Narrative Review of Neurotransmitters on Alzheimer's Disease: The Role of Therapeutic Interventions on Neurotransmission. Mol Neurobiol 2024:10.1007/s12035-024-04333-y. [PMID: 39012443 DOI: 10.1007/s12035-024-04333-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 06/24/2024] [Indexed: 07/17/2024]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease. The accumulation of amyloid-β (Aβ) plaques and tau neurofibrillary tangles are the key players responsible for the pathogenesis of the disease. The accumulation of Aβ plaques and tau affect the balance in chemical neurotransmitters in the brain. Thus, the current review examined the role of neurotransmitters in the pathogenesis of Alzheimer's disease and discusses the alterations in the neurochemical activity and cross talk with their receptors and transporters. In the presence of Aβ plaques and neurofibrillary tangles, changes may occur in the expression of neuronal receptors which in turn triggers excessive release of glutamate into the synaptic cleft contributing to cell death and neuronal damage. The GABAergic system may also be affected by AD pathology in a similar way. In addition, decreased receptors in the cholinergic system and dysfunction in the dopamine neurotransmission of AD pathology may also contribute to the damage to cognitive function. Moreover, the presence of deficiencies in noradrenergic neurons within the locus coeruleus in AD suggests that noradrenergic stimulation could be useful in addressing its pathophysiology. The regulation of melatonin, known for its effectiveness in enhancing cognitive function and preventing Aβ accumulation, along with the involvement of the serotonergic system and histaminergic system in cognition and memory, becomes remarkable for promoting neurotransmission in AD. Additionally, nitric oxide and adenosine-based therapeutic approaches play a protective role in AD by preventing neuroinflammation. Overall, neurotransmitter-based therapeutic strategies emerge as pivotal for addressing neurotransmitter homeostasis and neurotransmission in the context of AD. This review discussed the potential for neurotransmitter-based drugs to be effective in slowing and correcting the neurodegenerative processes in AD by targeting the neurochemical imbalance in the brain. Therefore, neurotransmitter-based drugs could serve as a future therapeutic strategy to tackle AD.
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Affiliation(s)
- Enes Akyuz
- Department of Biophysics, International School of Medicine, University of Health Sciences, Istanbul, Turkey
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Alina Arulsamy
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia.
| | | | - Bugra Sarisözen
- School of Medicine, Tekirdağ Namık Kemal University, Tekirdağ, Turkey
| | - Beyzanur Guney
- International School of Medicine, University of Health Sciences, Istanbul, Turkey
| | | | - Beyza Nur Yilmaz
- International School of Medicine, University of Health Sciences, Istanbul, Turkey
| | - Thaarvena Retinasamy
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia
| | - Mohd Farooq Shaikh
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia.
- School of Dentistry and Medical Sciences, Charles Sturt University, Orange, New South Wales, 2800, Australia.
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4
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Tejeda-Martínez AR, Ramos-Molina AR, Brand-Rubalcava PA, Flores-Soto ME. Involvement of serotonergic receptors in depressive processes and their modulation by β-arrestins: A review. Medicine (Baltimore) 2024; 103:e38943. [PMID: 38996114 PMCID: PMC11245247 DOI: 10.1097/md.0000000000038943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 07/14/2024] Open
Abstract
Over time, several studies have been conducted to demonstrate the functions of the neurotransmitter 5-hydroxytryptamine (5-HT), better known as serotonin. This neurotransmitter is associated with the modulation of various social and physiological behaviors, and its dysregulation has consequences at the behavioral level, leading to various neurophysiological disorders. Disorders such as anxiety, depression, schizophrenia, epilepsy, sexual disorders, and eating disorders, have been closely linked to variations in 5-HT concentrations and modifications in brain structures, including the raphe nuclei (RN), prefrontal cortex, basal ganglia, hippocampus, and hypothalamus, among others. The involvement of β-arrestin proteins has been implicated in the modulation of the serotonergic receptor response, as well as the activation of different signaling pathways related to the serotonergic system, this is particularly relevant in depressive disorders. This review will cover the implications of alterations in 5-HT receptor expression in depressive disorders in one hand and how β-arrestin proteins modulate the response mediated by these receptors in the other hand.
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Affiliation(s)
- Aldo R Tejeda-Martínez
- Laboratorio de Neurobiología Celular y Molecular, División de Neurociencias, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social, Guadalajara, México
| | - Ana R Ramos-Molina
- Laboratorio de Neurobiología Celular y Molecular, División de Neurociencias, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social, Guadalajara, México
| | - Patricia A Brand-Rubalcava
- Laboratorio de Neurobiología Celular y Molecular, División de Neurociencias, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social, Guadalajara, México
- Departamento de Ingeniería Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, México
| | - Mario E Flores-Soto
- Laboratorio de Neurobiología Celular y Molecular, División de Neurociencias, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano del Seguro Social, Guadalajara, México
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Mohole M, Naglekar A, Sengupta D, Chattopadhyay A. Probing the energy landscape of the lipid interactions of the serotonin 1A receptor. Biophys Chem 2024; 313:107289. [PMID: 39002247 DOI: 10.1016/j.bpc.2024.107289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 07/02/2024] [Accepted: 07/02/2024] [Indexed: 07/15/2024]
Abstract
G protein-coupled receptors (GPCRs) are lipid-regulated transmembrane proteins that play a central role in cell signaling and pharmacology. Although the role of membrane lipids in GPCR function is well established, the underlying GPCR-lipid interactions have not been thermodynamically characterized due to the complexity of these interactions. In this work, we estimate the energetics and dynamics of lipid association from coarse-grain simulations of the serotonin1A receptor embedded in a complex membrane. We show that lipids bind to the receptor with varying energetics of 1-4 kT, and timescales of 1-10 μs. The most favorable energetics and longest residence times are observed for cholesterol, glycosphingolipid GM1, phosphatidylethanolamine (PE) and phosphatidylserine (PS) lipids. Multi-exponential fitting of the contact probability suggests distinct dynamic regimes, corresponding to ps, ns and μs timescales, that we correlate with the annular, intermediate and non-annular lipid sites. The timescales of lipid binding correspond to high barrier heights, despite their relatively weaker energetics. Our results highlight that GPCR-lipid interactions are driven by both thermodynamic interactions and the dynamical features of lipid binding.
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Affiliation(s)
- Madhura Mohole
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Amit Naglekar
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Durba Sengupta
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
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6
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Gojani EG, Wang B, Li DP, Kovalchuk O, Kovalchuk I. The Impact of Psilocybin on High Glucose/Lipid-Induced Changes in INS-1 Cell Viability and Dedifferentiation. Genes (Basel) 2024; 15:183. [PMID: 38397173 PMCID: PMC10888174 DOI: 10.3390/genes15020183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
Serotonin emerges as a pivotal factor influencing the growth and functionality of β-cells. Psilocybin, a natural compound derived from mushrooms of the Psilocybe genus, exerts agonistic effects on the serotonin 5-HT2A and 5-HT2B receptors, thereby mimicking serotonin's behavior. This study investigates the potential impacts of psilocybin on β-cell viability, dedifferentiation, and function using an in vitro system. The INS-1 832/13 Rat Insulinoma cell line underwent psilocybin pretreatment, followed by exposure to high glucose-high lipid (HG-HL) conditions for specific time periods. After being harvested from treated cells, total transcript and cellular protein were utilized for further investigation. Our findings implied that psilocybin administration effectively mitigates HG-HL-stimulated β-cell loss, potentially mediated through the modulation of apoptotic biomarkers, which is possibly related to the mitigation of TXNIP, STAT-1, and STAT-3 phosphorylation. Furthermore, psilocybin exhibits the capacity to modulate the expression of key genes associated with β-cell dedifferentiation, including Pou5f1 and Nanog, indicating its potential in attenuating β-cell dedifferentiation. This research lays the groundwork for further exploration into the therapeutic potential of psilocybin in Type II diabetes intervention.
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Affiliation(s)
| | | | | | | | - Igor Kovalchuk
- Department of Biological Sciences, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada; (E.G.G.); (B.W.); (D.-P.L.); (O.K.)
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7
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Mitroshina EV, Marasanova EA, Vedunova MV. Functional Dimerization of Serotonin Receptors: Role in Health and Depressive Disorders. Int J Mol Sci 2023; 24:16416. [PMID: 38003611 PMCID: PMC10671093 DOI: 10.3390/ijms242216416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/11/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
Understanding the neurobiological underpinnings of depressive disorder constitutes a pressing challenge in the fields of psychiatry and neurobiology. Depression represents one of the most prevalent forms of mental and behavioral disorders globally. Alterations in dimerization capacity can influence the functional characteristics of serotonin receptors and may constitute a contributing factor to the onset of depressive disorders. The objective of this review is to consolidate the current understanding of interactions within the 5-HT receptor family and between 5-HT receptors and members of other receptor families. Furthermore, it aims to elucidate the role of such complexes in depressive disorders and delineate the mechanisms through which antidepressants exert their effects.
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Affiliation(s)
- Elena V. Mitroshina
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603022 Nizhny Novgorod, Russia; (E.A.M.)
| | - Ekaterina A. Marasanova
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603022 Nizhny Novgorod, Russia; (E.A.M.)
| | - Maria V. Vedunova
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603022 Nizhny Novgorod, Russia; (E.A.M.)
- Faculty of Biology and Biotechnology, HSE University, St. Profsoyuznaya, 33, 117418 Moscow, Russia
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8
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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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9
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Parajulee A, Kim K. Structural studies of serotonin receptor family. BMB Rep 2023; 56:527-536. [PMID: 37817438 PMCID: PMC10618075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/01/2023] [Accepted: 09/25/2023] [Indexed: 10/12/2023] Open
Abstract
Serotonin receptors, also known as 5-HT receptors, belong to the G protein-coupled receptors (GPCRs) superfamily. They mediate the effects of serotonin, a neurotransmitter that plays a key role in a wide range of functions including mood regulation, cognition and appetite. The functions of serotonin are mediated by a family of 5-HT receptors including 12 GPCRs belonging to six major families: 5-HT1, 5-HT2, 5-HT4, 5-HT5, 5-HT6 and 5-HT7. Despite their distinct characteristics and functions, these receptors' subtypes share common structural features and signaling mechanisms. Understanding the structure, functions and pharmacology of the serotonin receptor family is essential for unraveling the complexities of serotonin signaling and developing targeted therapeutics for neuropsychiatric disorders. However, developing drugs that selectively target specific receptor subtypes is challenging due to the structural similarities in their orthosteric binding sites. This review focuses on the recent advancements in the structural studies of 5-HT receptors, highlighting the key structural features of each subtype and shedding light on their potential as targets for mental health and neurological disorders (such as depression, anxiety, schizophrenia, and migraine) drugs. [BMB Reports 2023; 56(10): 527-536].
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Affiliation(s)
- Apeksha Parajulee
- Department of Pharmacy, College of Pharmacy, Yonsei University, Incheon 21983, Korea
| | - Kuglae Kim
- Department of Pharmacy, College of Pharmacy, Yonsei University, Incheon 21983, Korea
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10
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Govindula A, Ranadive N, Nampoothiri M, Rao CM, Arora D, Mudgal J. Emphasizing the Crosstalk Between Inflammatory and Neural Signaling in Post-traumatic Stress Disorder (PTSD). J Neuroimmune Pharmacol 2023; 18:248-266. [PMID: 37097603 PMCID: PMC10577110 DOI: 10.1007/s11481-023-10064-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 04/16/2023] [Indexed: 04/26/2023]
Abstract
Post-traumatic stress disorder (PTSD) is a chronic incapacitating condition with recurrent experience of trauma-related memories, negative mood, altered cognition, and hypervigilance. Agglomeration of preclinical and clinical evidence in recent years specified that alterations in neural networks favor certain characteristics of PTSD. Besides the disruption of hypothalamus-pituitary-axis (HPA) axis, intensified immune status with elevated pro-inflammatory cytokines and arachidonic metabolites of COX-2 such as PGE2 creates a putative scenario in worsening the neurobehavioral facet of PTSD. This review aims to link the Diagnostic and Statistical Manual of mental disorders (DSM-V) symptomology to major neural mechanisms that are supposed to underpin the transition from acute stress reactions to the development of PTSD. Also, to demonstrate how these intertwined processes can be applied to probable early intervention strategies followed by a description of the evidence supporting the proposed mechanisms. Hence in this review, several neural network mechanisms were postulated concerning the HPA axis, COX-2, PGE2, NLRP3, and sirtuins to unravel possible complex neuroinflammatory mechanisms that are obscured in PTSD condition.
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Affiliation(s)
- Anusha Govindula
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Niraja Ranadive
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Madhavan Nampoothiri
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - C Mallikarjuna Rao
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Devinder Arora
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India.
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast campus, Gold Coast, Queensland, 4222, Australia.
| | - Jayesh Mudgal
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India.
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11
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Jaster AM, González-Maeso J. Mechanisms and molecular targets surrounding the potential therapeutic effects of psychedelics. Mol Psychiatry 2023; 28:3595-3612. [PMID: 37759040 DOI: 10.1038/s41380-023-02274-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023]
Abstract
Psychedelics, also known as classical hallucinogens, have been investigated for decades due to their potential therapeutic effects in the treatment of neuropsychiatric and substance use disorders. The results from clinical trials have shown promise for the use of psychedelics to alleviate symptoms of depression and anxiety, as well as to promote substantial decreases in the use of nicotine and alcohol. While these studies provide compelling evidence for the powerful subjective experience and prolonged therapeutic adaptations, the underlying molecular reasons for these robust and clinically meaningful improvements are still poorly understood. Preclinical studies assessing the targets and circuitry of the post-acute effects of classical psychedelics are ongoing. Current literature is split between a serotonin 5-HT2A receptor (5-HT2AR)-dependent or -independent signaling pathway, as researchers are attempting to harness the mechanisms behind the sustained post-acute therapeutically relevant effects. A combination of molecular, behavioral, and genetic techniques in neuropharmacology has begun to show promise for elucidating these mechanisms. As the field progresses, increasing evidence points towards the importance of the subjective experience induced by psychedelic-assisted therapy, but without further cross validation between clinical and preclinical research, the why behind the experience and its translational validity may be lost.
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Affiliation(s)
- Alaina M Jaster
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Javier González-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.
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Bernatoniene J, Sciupokas A, Kopustinskiene DM, Petrikonis K. Novel Drug Targets and Emerging Pharmacotherapies in Neuropathic Pain. Pharmaceutics 2023; 15:1799. [PMID: 37513986 PMCID: PMC10384314 DOI: 10.3390/pharmaceutics15071799] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/30/2023] Open
Abstract
Neuropathic pain is a debilitating condition characterized by abnormal signaling within the nervous system, resulting in persistent and often intense sensations of pain. It can arise from various causes, including traumatic nerve injury, neuropathy, and certain diseases. We present an overview of current and emerging pharmacotherapies for neuropathic pain, focusing on novel drug targets and potential therapeutic agents. Current pharmacotherapies, including tricyclic antidepressants, gabapentinoids, and serotonin norepinephrine re-uptake inhibitors, are discussed, as are emerging treatments, such as ambroxol, cannabidiol, and N-acetyl-L-cysteine. Additionally, the article highlights the need for further research in this field to identify new targets and develop more effective and targeted therapies for neuropathic pain management.
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Affiliation(s)
- Jurga Bernatoniene
- Department of Drug Technology and Social Pharmacy, Faculty of Pharmacy, Medical Academy, Lithuanian University of Health Sciences, Sukileliu pr. 13, LT-50161 Kaunas, Lithuania
- Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Medical Academy, Lithuanian University of Health Sciences, Sukileliu pr. 13, LT-50161 Kaunas, Lithuania
| | - Arunas Sciupokas
- Pain Clinic, Lithuanian University of Health Sciences Hospital Kauno Klinikos, Eivenių Str. 2, LT-50009 Kaunas, Lithuania
- Department of Neurology, Lithuanian University of Health Sciences, Eivenių Str. 2, LT-50009 Kaunas, Lithuania
| | - Dalia Marija Kopustinskiene
- Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Medical Academy, Lithuanian University of Health Sciences, Sukileliu pr. 13, LT-50161 Kaunas, Lithuania
| | - Kestutis Petrikonis
- Department of Neurology, Lithuanian University of Health Sciences, Eivenių Str. 2, LT-50009 Kaunas, Lithuania
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Calderón JC, Ibrahim P, Gobbo D, Gervasio FL, Clark T. General Metadynamics Protocol To Simulate Activation/Deactivation of Class A GPCRs: Proof of Principle for the Serotonin Receptor. J Chem Inf Model 2023; 63:3105-3117. [PMID: 37161278 DOI: 10.1021/acs.jcim.3c00208] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We present a generally applicable metadynamics protocol for characterizing the activation free-energy profiles of class A G-protein coupled receptors and a proof-of-principle study for the 5HT1A-receptor. The almost universal A100 activation index, which depends on five inter-helix distances, is used as the single collective variable in well-tempered multiple-walker metadynamics simulations. Here, we show free-energy profiles for the serotonin receptor as binary (apo-receptor + G-protein-α-subunit and receptor + ligand) and ternary complexes with two prototypical orthosteric ligands: the full agonist serotonin and the partial agonist aripiprazole. Our results are not only compatible with previously reported experimental and computational data, but they also allow differences between active and inactive conformations to be determined in unprecedented atomic detail, and with respect to the so-called microswitches that have been suggested as determinants of activation, giving insight into their role in the activation mechanism.
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Affiliation(s)
- Jacqueline C Calderón
- Computer-Chemistry-Center, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nuernberg, Naegelsbachstr. 25, 91052 Erlangen, Germany
| | - Passainte Ibrahim
- Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, Leipzig 04107, Germany
| | - Dorothea Gobbo
- Pharmaceutical Sciences, University of Geneva, CH1206 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, CH1206 Geneva, Switzerland
| | - Francesco Luigi Gervasio
- Pharmaceutical Sciences, University of Geneva, CH1206 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, CH1206 Geneva, Switzerland
- Chemistry Department, University College London, WC1H 0AJ London, U.K
| | - Timothy Clark
- Computer-Chemistry-Center, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nuernberg, Naegelsbachstr. 25, 91052 Erlangen, Germany
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14
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Isu UH, Badiee SA, Khodadadi E, Moradi M. Cholesterol in Class C GPCRs: Role, Relevance, and Localization. MEMBRANES 2023; 13:301. [PMID: 36984688 PMCID: PMC10056374 DOI: 10.3390/membranes13030301] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
G-protein coupled receptors (GPCRs), one of the largest superfamilies of cell-surface receptors, are heptahelical integral membrane proteins that play critical roles in virtually every organ system. G-protein-coupled receptors operate in membranes rich in cholesterol, with an imbalance in cholesterol level within the vicinity of GPCR transmembrane domains affecting the structure and/or function of many GPCRs, a phenomenon that has been linked to several diseases. These effects of cholesterol could result in indirect changes by altering the mechanical properties of the lipid environment or direct changes by binding to specific sites on the protein. There are a number of studies and reviews on how cholesterol modulates class A GPCRs; however, this area of study is yet to be explored for class C GPCRs, which are characterized by a large extracellular region and often form constitutive dimers. This review highlights specific sites of interaction, functions, and structural dynamics involved in the cholesterol recognition of the class C GPCRs. We summarize recent data from some typical family members to explain the effects of membrane cholesterol on the structural features and functions of class C GPCRs and speculate on their corresponding therapeutic potential.
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15
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Kumar A, Sarkar P, Chattopadhyay A. Metabolic depletion of sphingolipids inhibits agonist-induced endocytosis of the serotonin 1A receptor. Traffic 2023; 24:95-107. [PMID: 36533718 DOI: 10.1111/tra.12879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 10/11/2022] [Accepted: 10/18/2022] [Indexed: 12/23/2022]
Abstract
G protein-coupled receptors (GPCRs) are vital cellular signaling machinery and currently represent ~40% drug targets. Endocytosis of GPCRs is an important process that allows stringent spatiotemporal control over receptor population on the cell surface. Although the role of proteins in GPCR endocytosis is well addressed, the contribution of membrane lipids in this process is rather unexplored. Sphingolipids are essential functional lipids in higher eukaryotes and are implicated in several neurological functions. To understand the role of sphingolipids in GPCR endocytosis, we subjected cells expressing human serotonin1A receptors (an important neurotransmitter GPCR involved in cognitive and behavioral functions) to metabolic sphingolipid depletion using fumonisin B1 , an inhibitor of sphingolipid biosynthetic pathway. Our results, using flow cytometric analysis and confocal microscopic imaging, show that sphingolipid depletion inhibits agonist-induced endocytosis of the serotonin1A receptor in a concentration-dependent manner, which was restored when sphingolipid levels were replenished. We further show that there was no change in the internalization of transferrin, a marker for clathrin-mediated endocytosis, under sphingolipid-depleted condition, highlighting the specific requirement of sphingolipids for endocytosis of serotonin1A receptors. Our results reveal the regulatory role of sphingolipids in GPCR endocytosis and highlight the importance of neurotransmitter receptor trafficking in health and disease.
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Affiliation(s)
- Abhishek Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Amity Institute of Biotechnology, Amity University Haryana, Gurugram, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
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16
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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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17
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Jiang Y, Lu Y, Cai Y, Liu C, Zhang XY. Prevalence of suicide attempts and correlates among first-episode and untreated major depressive disorder patients with comorbid dyslipidemia of different ages of onset in a Chinese Han population: a large cross-sectional study. BMC Psychiatry 2023; 23:10. [PMID: 36600266 PMCID: PMC9814200 DOI: 10.1186/s12888-022-04511-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 12/30/2022] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Patients with dyslipidemia are at increased risk for suicide, especially those with major depressive disorder (MDD). Few studies have investigated the independent effects of suicide attempts on comorbid dyslipidemia in patients with MDD. Moreover, there are no comparisons of differences in factors associated with suicide attempts among patients with MDD with dyslipidemia at different ages of onset. The aim of this study was to investigate the prevalence of suicide attempts and associated variables in first episode and untreated patients with MDD with comorbid dyslipidemia at different ages of onset. METHODS We recruited 1718 patients with first-episode untreated MDD in this study. Demographical and clinical data were collected, and lipid profiles, thyroid function, and blood glucose levels were measured. The Hamilton Depression Scale 17 (HAMD-17), Hamilton Anxiety Scale (HAMA), Clinical Global Impression Severity Scale (CGI), and Positive and Negative Syndrome Scale (PANSS) positive subscale were assessed for depression, anxiety and illness severity, as well as psychotic symptoms, respectively. RESULTS The percentage of patients with MDD with comorbid dyslipidemia was 61% (1048/1718). Among patients with MDD with comorbid dyslipidemia, the incidence of suicide attempts was 22.2% (170/765) for early adulthood onset and 26.5% (75/283) for mid-adulthood onset. Independent factors associated with suicide attempts in early adulthood onset patients with MDD with dyslipidemia were as follows: HAMA score (B = 0.328, P < 0.0001, OR = 1.388), Suspicion /persecution (B = -0.554, P = 0.006, OR = 0.575), CGI (B = 0.878, P < 0.0001, OR = 2.406), systolic blood pressure (B = 0.048, P = 0.004, OR = 1.049), hallucinatory behavior (B = 0.334, P = 0.025, OR = 1.397), and TPOAb (B = 0.003, p < 0.0001, OR = 1.003). Independent factors associated with suicide attempts in mid-adulthood onset patients with MDD with comorbid dyslipidemia were as follows: HAMA score (B = 0.182, P < 0.0001, OR = 1.200), CGI (B = 1.022, P < 0.0001, OR = 2.778), and TPOAb (B = 0.002, P = 0.009, OR = 1.002). CONCLUSION Our findings suggest an elevated risk of suicide attempts in patients with MDD with comorbid dyslipidemia. The incidence of suicide attempts was similar in the early- and mid-adulthood onset subgroups among patients with MDD with dyslipidemia, but the factors associated with suicide attempts were different in these two subgroups.
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Affiliation(s)
- Yang Jiang
- Guangxi Zhuang Autonomous Region Brain Hospital, Guangxi Liuzhou, 545005, China
| | - Yaoyao Lu
- Guangxi Zhuang Autonomous Region Brain Hospital, Guangxi Liuzhou, 545005, China
| | - Yi Cai
- Department of Psychosomatic Disorders, Shenzhen Mental Health Center/Shenzhen KangNing Hospital, Shenzhen, 518000, Guangdong, China
| | - Chengjiang Liu
- Department of General Medicine, Anhui Medical University, He Fei, 230601, China
| | - Xiang-Yang Zhang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, 100101, China.
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18
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Schirripa Spagnolo C, Luin S. Setting up multicolour TIRF microscopy down to the single molecule level. Biomol Concepts 2023; 14:bmc-2022-0032. [PMID: 37428621 DOI: 10.1515/bmc-2022-0032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 06/26/2023] [Indexed: 07/12/2023] Open
Abstract
Investigating biological mechanisms in ever greater detail requires continuous advances in microscopy techniques and setups. Total internal reflection fluorescence (TIRF) microscopy is a well-established technique for visualizing processes on the cell membrane. TIRF allows studies down to the single molecule level, mainly in single-colour applications. Instead, multicolour setups are still limited. Here, we describe our strategies for implementing a multi-channel TIRF microscopy system capable of simultaneous two-channel excitation and detection, starting from a single-colour commercial setup. First, we report some applications at high molecule density and then focus on the challenges we faced for achieving the single molecule level simultaneously in different channels, showing that rigorous optimizations on the setup are needed to increase its sensitivity up to this point, from camera setting to background minimization. We also discuss our strategies regarding crucial points of fluorescent labelling for this type of experiment: labelling strategy, kind of probe, efficiency, and orthogonality of the reaction, all of which are aspects that can influence the achievable results. This work may provide useful guidelines for setting up advanced single-molecule multi-channel TIRF experiments to obtain insights into interaction mechanisms on the cell membrane of living cells.
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Affiliation(s)
| | - Stefano Luin
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, I-56127, Pisa, Italy
- NEST Laboratory, Istituto Nanoscienze-Consiglio Nazionale delle ricerche (CNR), Piazza San Silvestro 12, I-56127, Pisa, Italy
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19
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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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20
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Lipid composition dependent binding of apolipoprotein E signal peptide: Importance of membrane cholesterol in protein trafficking. Biophys Chem 2022; 291:106907. [DOI: 10.1016/j.bpc.2022.106907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 11/17/2022]
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21
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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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22
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Shrivastava S, Sarkar P, Preira P, Salomé L, Chattopadhyay A. Cholesterol-Dependent Dynamics of the Serotonin 1A Receptor Utilizing Single Particle Tracking: Analysis of Diffusion Modes. J Phys Chem B 2022; 126:6682-6690. [PMID: 35973070 DOI: 10.1021/acs.jpcb.2c03941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
G protein-coupled receptors (GPCRs) are signaling hubs in cell membranes that regulate a wide range of physiological processes and are popular drug targets. Serotonin1A receptors are important members of the GPCR family and are implicated in neuropsychiatric disorders. Cholesterol is a key constituent of higher eukaryotic membranes and is believed to contribute to the segregated distribution of membrane constituents into domains. To explore the role of cholesterol in lateral dynamics of GPCRs, we utilized single particle tracking (SPT) to monitor diffusion of serotonin1A receptors under acute and chronic cholesterol-depleted conditions. Our results show that the short-term diffusion coefficient of the receptor decreases upon cholesterol depletion, irrespective of the method of cholesterol depletion. Analysis of SPT trajectories revealed that relative populations of receptors undergoing various modes of diffusion change upon cholesterol depletion. Notably, in cholesterol-depleted cells, we observed an increase in the confined population of the receptor accompanied by a reduction in diffusion coefficient for chronic cholesterol depletion. These results are supported by our recent work and present observations that show polymerization of G-actin in response to chronic cholesterol depletion. Taken together, our results bring out the interdependence of cholesterol and actin cytoskeleton in regulating diffusion of GPCRs in membranes.
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Affiliation(s)
- Sandeep Shrivastava
- 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
| | - Pascal Preira
- Institut de Pharmacologie et de Biologie Structurale, CNRS, Université de Toulouse (UPS), 31 077 Toulouse, France
| | - Laurence Salomé
- Institut de Pharmacologie et de Biologie Structurale, CNRS, Université de Toulouse (UPS), 31 077 Toulouse, France
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23
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Sarkar P, Chattopadhyay A. Statin-induced Increase in Actin Polymerization Modulates GPCR Dynamics and Compartmentalization. Biophys J 2022:S0006-3495(22)00708-1. [DOI: 10.1016/j.bpj.2022.08.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/16/2022] [Accepted: 08/25/2022] [Indexed: 11/29/2022] Open
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Sarkar P, Chattopadhyay A. Membrane Dipole Potential: An Emerging Approach to Explore Membrane Organization and Function. J Phys Chem B 2022; 126:4415-4430. [PMID: 35696090 DOI: 10.1021/acs.jpcb.2c02476] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biological membranes are complex organized molecular assemblies of lipids and proteins that provide cells and membrane-bound intracellular organelles their individual identities by morphological compartmentalization. Membrane dipole potential originates from the electrostatic potential difference within the membrane due to the nonrandom arrangement (orientation) of amphiphile and solvent (water) dipoles at the membrane interface. In this Feature Article, we will focus on the measurement of dipole potential using electrochromic fluorescent probes and highlight interesting applications. In addition, we will focus on ratiometric fluorescence microscopic imaging technique to measure dipole potential in cellular membranes, a technique that can be used to address novel problems in cell biology which are otherwise difficult to address using available approaches. We envision that membrane dipole potential could turn out to be a convenient tool in exploring the complex interplay between membrane lipids and proteins and could provide novel insights in membrane organization and function.
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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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25
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Cholesterol occupies the lipid translocation pathway to block phospholipid scrambling by a G protein-coupled receptor. Structure 2022; 30:1208-1217.e2. [PMID: 35660161 PMCID: PMC9356978 DOI: 10.1016/j.str.2022.05.010] [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: 03/08/2022] [Revised: 04/28/2022] [Accepted: 05/11/2022] [Indexed: 11/21/2022]
Abstract
Class A (rhodopsin-like) G protein-coupled receptors (GPCRs) are constitutive phospholipid scramblases as evinced after their reconstitution into liposomes. Yet phospholipid scrambling is not detectable in the resting plasma membrane of mammalian cells that is replete with GPCRs. We considered whether cholesterol, a prominent component of the plasma membrane, limits the ability of GPCRs to scramble lipids. Our previous Markov State Model (MSM) analysis of molecular dynamics simulations of membrane-embedded opsin indicated that phospholipid headgroups traverse a dynamically revealed hydrophilic groove between transmembrane helices (TM) 6 and 7 while their tails remain in the bilayer. Here, we present comparative MSM analyses of 150-μs simulations of opsin in cholesterol-free and cholesterol-rich membranes. Our analyses reveal that cholesterol inhibits phospholipid scrambling by occupying the TM6/7 interface and stabilizing the closed groove conformation while itself undergoing flip-flop. This mechanism may explain the inability of GPCRs to scramble lipids at the plasma membrane.
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26
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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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27
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Mozumder S, Bej A, Sengupta J. Ligand-Dependent Modulation of the Dynamics of Intracellular Loops Dictates Functional Selectivity of 5-HT 2AR. J Chem Inf Model 2022; 62:2522-2537. [PMID: 35324173 DOI: 10.1021/acs.jcim.2c00118] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The serotonin 2A receptor (5-HT2AR) subtype of the G protein-coupled receptor (GPCR) family is involved in a plethora of neuromodulatory functions (e.g., neurogenesis, sleep, and cognitive processes). 5-HT2AR is the target of pharmacologically distinct classes of ligands, binding of which either activate or inactivate the receptor. Although high-resolution structures of 5-HT2AR as well as several other 5-HT GPCRs provided snapshots of both active and inactive conformational states, these structures, representing a truncated form of the receptor, cannot fully explain the mechanism of conformational transitions during their function. Importantly, biochemical studies have suggested the importance of intracellular loops in receptor functions. In our previous study, a model of the ligand-free form of 5-HT2AR with the third intracellular loop (ICL3) has been meticulously built. Here, we have investigated the functional regulation of 5-HT2AR with intact intracellular loops in ligand-free and five distinct ligand-bound configurations using unbiased atomistic molecular dynamics (MD) simulations. The selected ligands belong to either of the full, partial, or inverse agonist classes, which exert distinct pharmacological responses. We have observed significant structural, dynamic, and thermodynamic differences within ligand-bound complexes. Our results revealed, for the first time, that either activation or inactivation of the receptor upon specific ligand binding is primarily achieved through conformational transitions of its second and third intracellular loops (ICL2 and ICL3). A remarkable allosteric cross-talk between the ligand-binding site and the distal intracellular parts of the receptor, where binding of a specific ligand thermodynamically controls (either stabilizes or destabilizes) the intracellular region, consisting of crucial dynamic elements ICL2 and ICL3, and differential conformational transitions of these loops determine ligand-dependent functional selectivity.
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Affiliation(s)
- Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Aritra Bej
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700032, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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Johnston JN, Campbell D, Caruncho HJ, Henter ID, Ballard ED, Zarate CA. Suicide Biomarkers to Predict Risk, Classify Diagnostic Subtypes, and Identify Novel Therapeutic Targets: 5 Years of Promising Research. Int J Neuropsychopharmacol 2022; 25:197-214. [PMID: 34865007 PMCID: PMC8929755 DOI: 10.1093/ijnp/pyab083] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/02/2021] [Accepted: 11/30/2021] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Suicide is a global health crisis. However, no objective biomarkers of suicide risk currently exist, and self-reported data can be unreliable, which limits prediction, diagnostic, and treatment efforts. Reliable biomarkers that can differentiate between diagnostic subgroups, predict worsening symptoms, or suggest novel therapeutic targets would be extremely valuable for patients, researchers, and clinicians. METHODS MEDLINE was searched for reports published between 2016 and 2021 using search terms (suicid*) AND (biomarker*) OR (indicat*). Reports that compared biomarkers between suicidal ideation, suicide attempt, death from suicide, or any suicide subgroup against other neuropsychiatric disorders were included. Studies exclusively comparing suicidal behavior or death from suicide with healthy controls were not included to ensure that biomarkers were specific to suicide and not other psychopathology. RESULTS This review summarizes the last 5 years of research into suicide-associated biomarkers and provides a comprehensive guide for promising and novel biomarkers that encompass varying presentations of suicidal ideation, suicide attempt, and death by suicide. The serotonergic system, inflammation, hypothalamic-pituitary-adrenal axis, lipids, and endocannabinoids emerged as the most promising diagnostic, predictive, and therapeutic indicators. CONCLUSIONS The utility of diagnostic and predictive biomarkers is evident, particularly for suicide prevention. While larger-scale studies and further in-depth research are required, the last 5 years of research has uncovered essential biomarkers that could ultimately improve predictive strategies, aid diagnostics, and help develop future therapeutic targets.
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Affiliation(s)
- Jenessa N Johnston
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
- Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland,USA
| | - Darcy Campbell
- Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland,USA
| | - Hector J Caruncho
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
- Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland,USA
| | - Ioline D Henter
- Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland,USA
| | - Elizabeth D Ballard
- Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland,USA
| | - Carlos A Zarate
- Experimental Therapeutics and Pathophysiology Branch, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland,USA
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Pal S, Chattopadhyay A. Hydration Dynamics in Biological Membranes: Emerging Applications of Terahertz Spectroscopy. J Phys Chem Lett 2021; 12:9697-9709. [PMID: 34590862 DOI: 10.1021/acs.jpclett.1c02576] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Water drives the spontaneous self-assembly of lipids and proteins into quasi two-dimensional biological membranes that act as catalytic scaffolds for numerous processes central to life. However, the functional relevance of hydration in membrane biology is only beginning to be addressed, predominantly because of challenges associated with direct measurements of hydration microstructure and dynamics in a biological milieu. Our recent work on the novel interplay of membrane electrostatics and crowding in shaping membrane hydration dynamics utilizing terahertz (THz) spectroscopy represents an important step in this context. In this Perspective, we provide a glimpse into the ever-broadening functional landscape of hydration dynamics in biological membranes in the backdrop of the unique physical chemistry of water molecules. We further highlight the immense (and largely untapped) potential of the THz toolbox in addressing contemporary problems in membrane biology, while emphasizing the adaptability of the analytical framework reported recently by us to such studies.
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Affiliation(s)
- Sreetama Pal
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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Sharma A, Kumar GA, Chattopadhyay A. Late endosomal/lysosomal accumulation of a neurotransmitter receptor in a cellular model of Smith-Lemli-Opitz syndrome. Traffic 2021; 22:332-344. [PMID: 34418249 DOI: 10.1111/tra.12811] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/17/2022]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a congenital and developmental malformation syndrome associated with defective cholesterol biosynthesis. It is characterized by accumulation of 7-dehydrocholesterol (the immediate biosynthetic precursor of cholesterol in the Kandutsch-Russell pathway) and an altered cholesterol to total sterol ratio. Because SLOS is associated with neurological malfunction, exploring the function and trafficking of neuronal receptors and their interaction with membrane lipids under these conditions assume significance. In this work, we generated a cellular model of SLOS in HEK-293 cells stably expressing the human serotonin1A receptor (an important neurotransmitter G-protein coupled receptor) using AY 9944, an inhibitor for the enzyme 3β-hydroxy-steroid-∆7 -reductase (7-DHCR). Using a quantitative flow cytometry based assay, we show that the plasma membrane population of serotonin1A receptors was considerably reduced under these conditions without any change in total cellular expression of the receptor. Interestingly, the receptors were trafficked to sterol-enriched LysoTracker positive compartments, which accumulated under these conditions. To the best of our knowledge, our results constitute one of the first reports demonstrating intracellular accumulation and misregulated traffic of a neurotransmitter GPCR in SLOS-like conditions. We believe these results assume relevance in our overall understanding of the molecular basis underlying the functional relevance of neurotransmitter receptors in SLOS.
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Affiliation(s)
- Ashwani Sharma
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
| | - G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
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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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32
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Kumar GA, Sarkar P, Stepniewski TM, Jafurulla M, Singh SP, Selent J, Chattopadhyay A. A molecular sensor for cholesterol in the human serotonin 1A receptor. SCIENCE ADVANCES 2021; 7:7/30/eabh2922. [PMID: 34301606 PMCID: PMC8302130 DOI: 10.1126/sciadv.abh2922] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/09/2021] [Indexed: 05/10/2023]
Abstract
The function of several G protein-coupled receptors (GPCRs) exhibits cholesterol sensitivity. Cholesterol sensitivity of GPCRs could be attributed to specific sequence and structural features, such as the cholesterol recognition/interaction amino acid consensus (CRAC) motif, that facilitate their cholesterol-receptor interaction. In this work, we explored the molecular basis of cholesterol sensitivity exhibited by the serotonin1A receptor, the most studied GPCR in the context of cholesterol sensitivity, by generating mutants of key residues in CRAC motifs in transmembrane helix 2 (TM2) and TM5 of the receptor. Our results show that a lysine residue (K101) in one of the CRAC motifs is crucial for sensing altered membrane cholesterol levels. Insights from all-atom molecular dynamics simulations showed that cholesterol-sensitive functional states of the serotonin1A receptor are associated with reduced conformational dynamics of extracellular loops of the receptor. These results constitute one of the first reports on the molecular mechanism underlying cholesterol sensitivity of GPCRs.
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Affiliation(s)
- G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Tomasz Maciej Stepniewski
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Md Jafurulla
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Shishu Pal Singh
- National Centre for Biological Sciences, UAS-GKVK Campus, Bellary Road, Bengaluru 560 065, India
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain.
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Environment-Sensitive Fluorescence of 7-Nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-Labeled Ligands for Serotonin Receptors. Molecules 2021; 26:molecules26133848. [PMID: 34202630 PMCID: PMC8270269 DOI: 10.3390/molecules26133848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
Serotonin is a neurotransmitter that plays a crucial role in the regulation of several behavioral and cognitive functions by binding to a number of different serotonin receptors present on the cell surface. We report here the synthesis and characterization of several novel fluorescent analogs of serotonin in which the fluorescent NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl) group is covalently attached to serotonin. The fluorescent ligands compete with the serotonin1A receptor specific radiolabeled agonist for binding to the receptor. Interestingly, these fluorescent ligands display a high environmental sensitivity of their fluorescence. Importantly, the human serotonin1A receptor stably expressed in CHO-K1 cells could be specifically labeled with one of the fluorescent ligands with minimal nonspecific labeling. Interestingly, we show by spectral imaging that the NBD-labeled ligand exhibits a red edge excitation shift (REES) of 29 nm when bound to the receptor, implying that it is localized in a restricted microenvironment. Taken together, our results show that NBD-labeled serotonin analogs offer an attractive fluorescent approach for elucidating the molecular environment of the serotonin binding site in serotonin receptors. In view of the multiple roles played by the serotonergic systems in the central and peripheral nervous systems, these fluorescent ligands would be useful in future studies involving serotonin receptors.
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Kumar A, Sarkar P, Chattopadhyay A. Metabolic Depletion of Sphingolipids Reduces Cell Surface Population of the Human Serotonin 1A Receptor due to Impaired Trafficking. ACS Chem Neurosci 2021; 12:1189-1196. [PMID: 33760584 DOI: 10.1021/acschemneuro.1c00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sphingolipids and their metabolites are increasingly implicated in the pathogenesis of many metabolic and neurological diseases. It has been postulated that sphingolipids coalesce with cholesterol to form laterally segregated lipid domains that are involved in protein sorting and trafficking. In this work, we have explored the effect of metabolic depletion of sphingolipids on cell surface expression of the human serotonin1A receptor, a neurotransmitter G protein-coupled receptor. We used fumonisin B1 (FB1), a fungal mycotoxin, to inhibit sphingolipid biosynthesis in HEK-293 cells stably expressing the human serotonin1A receptor. Our results obtained using flow cytometric analysis and confocal microscopic imaging show that the cell surface population of the serotonin1A receptor is reduced under sphingolipid-depleted condition. Western blot analysis confirmed that there was no significant difference in total cellular level of the serotonin1A receptor upon depletion of sphingolipids. Interestingly, the effect of FB1 on serotonin1A receptor population was reversed upon replenishment with sphingolipids. These results indicate that sphingolipid depletion does not alter total cellular receptor levels, but impairs serotonin1A receptor trafficking to the cellular plasma membrane. These results could provide mechanistic insights into the role of sphingolipids in modulation of neurotransmitter receptor signaling and trafficking in health and disease.
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Affiliation(s)
- Abhishek Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- Amity Institute of Biotechnology, Amity University Haryana, Amity Education Valley, Gurugram 122 413, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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Affiliation(s)
- Damien Hall
- WPI Nano Life Science Institute, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa 920-1164 Japan
- Department of Life Sciences and Applied Chemistry, Nagoya Institute of Technology, Gokiso Showa, Nagoya, Aichi 466-8555 Japan
- Department of Applied Physics, Alto University, Aalto, FI-00076 Finland
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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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