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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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Benhadda A, Delhaye C, Moutkine I, Marques X, Russeau M, Le Magueresse C, Roumier A, Lévi S, Maroteaux L. 5-HT 1A and 5-HT 2B receptor interaction and co-clustering regulate serotonergic neuron excitability. iScience 2023; 26:107401. [PMID: 37575185 PMCID: PMC10415917 DOI: 10.1016/j.isci.2023.107401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/26/2023] [Accepted: 07/12/2023] [Indexed: 08/15/2023] Open
Abstract
Many psychiatric diseases have been associated with serotonin (5-HT) neuron dysfunction. The firing of 5-HT neurons is known to be under 5-HT1A receptor-mediated autoinhibition, but functional consequences of coexpressed receptors are unknown. Using co-immunoprecipitation, BRET, confocal, and super-resolution microscopy in hippocampal and 5-HT neurons, we present evidence that 5-HT1A and 5-HT2B receptors can form heterodimers and co-cluster at the plasma membrane of dendrites. Selective agonist stimulation of coexpressed 5-HT1A and 5-HT2B receptors prevents 5-HT1A receptor internalization and increases 5-HT2B receptor membrane clustering. Current clamp recordings of 5-HT neurons revealed that 5-HT1A receptor stimulation of acute slices from mice lacking 5-HT2B receptors in 5-HT neurons increased their firing activity trough Ca2+-activated potassium channel inhibition compared to 5-HT neurons from control mice. This work supports the hypothesis that the relative expression of 5-HT1A and 5-HT2B receptors tunes the neuronal excitability of serotonergic neurons through potassium channel regulation.
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Affiliation(s)
- Amina Benhadda
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Célia Delhaye
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Imane Moutkine
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Xavier Marques
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Marion Russeau
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Corentin Le Magueresse
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Anne Roumier
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Sabine Lévi
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
| | - Luc Maroteaux
- Institut du Fer à Moulin, U1270 INSERM, Sorbonne Université, 17 rue du Fer à Moulin, 75005 Paris, France
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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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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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Rosenhouse-Dantsker A, Gazgalis D, Logothetis DE. PI(4,5)P 2 and Cholesterol: Synthesis, Regulation, and Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:3-59. [PMID: 36988876 DOI: 10.1007/978-3-031-21547-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P2 and cholesterol are involved. While PI(4,5)P2 and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P2 in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P2 in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P2 and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.
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Affiliation(s)
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
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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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Raphe serotonin projections dynamically regulate feeding behavior through targeting inhibitory circuits from rostral zona incerta to paraventricular thalamus. Mol Metab 2022; 66:101634. [PMID: 36351530 PMCID: PMC9672487 DOI: 10.1016/j.molmet.2022.101634] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 11/08/2022] Open
Abstract
OBJECTIVE Rostral zona incerta (ZIR) evokes feeding by sending GABA transmission to paraventricular thalamus (PVT). Although central serotonin (5-HT) signaling is known to play critical roles in the regulation of food intake and eating disorders, it remains unknown whether raphe 5-HT neurons functionally innervate ZIR-PVT neural pathway for feeding control. Here, we sought to reveal how raphe 5-HT signaling regulates both ZIR and PVT for feeding control. METHODS We used retrograde neural tracers to map 5-HT projections in Sert-Cre mice and slice electrophysiology to examine the mechanism by which 5-HT modulates ZIR GABA neurons. We also used optogenetics to test the effects of raphe-ZIR and raphe-PVT 5-HT projections on feeding motivation and food intake in mice regularly fed, 24 h fasted, and with intermittent high-fat high-sugar (HFHS) diet. In addition, we applied RNAscope in situ hybridization to identify 5-HT receptor subtype mRNA in ZIR. RESULTS We show raphe 5-HT neurons sent projections to both ZIR and PVT with partial collateral axons. Photostimulation of 5-HT projections inhibited ZIR but excited PVT neurons to decrease motivated food consumption. However, both acute food deprivation and intermittent HFHS diet downregulated 5-HT inhibition on ZIR GABA neurons, abolishing the inhibitory regulation of raphe-ZIR 5-HT projections on feeding motivation and food intake. Furthermore, we found high-level 5-HT1a and 5-HT2c as well as low-level 5-HT7 mRNA expression in ZIR. Intermittent HFHS diet increased 5-HT7 but not 5-HT1a or 5-HT2c mRNA levels in the ZIR. CONCLUSIONS Our results reveal that raphe-ZIR 5-HT projections dynamically regulate ZIR GABA neurons for feeding control, supporting that a dynamic fluctuation of ZIR 5-HT inhibition authorizes daily food intake but a sustained change of ZIR 5-HT signaling leads to overeating induced by HFHS diet.
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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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Liang K, Mei S, Gao X, Peng S, Zhan J. Dynamics of Endocytosis and Degradation of Antibody-Drug Conjugate T-DM1 in HER2 Positive Cancer Cells. Drug Des Devel Ther 2022; 15:5135-5150. [PMID: 34992350 PMCID: PMC8713712 DOI: 10.2147/dddt.s344052] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 12/14/2021] [Indexed: 12/29/2022] Open
Abstract
Purpose T-DM1 is an antibody–drug conjugate (ADC) consisting of trastuzumab and DM1 linked together. T-DM1 binds to human epidermal growth factor receptor-2 (HER2) in tumors and then triggers the endocytosis of T-DM1 and release of payload. Therefore, endocytosis efficacy is considered as a critical step for the initiation of T-DM1 therapy; however, the endocytosis mechanism of T-DM1 remains poorly understood. Meanwhile, HER2 is regarded as an internalization-resistant receptor, which hinders the endocytosis and effectiveness of T-DM1. The present study is to explore the T-DM1 endocytosis pathway, which may provide insights into the internalization mechanism of ADCs and help to improve efficacy. Methods Confocal microscopy and flow cytometry were used to analyse T-DM1 intracellular trafficking and endocytosis efficiency, while Western blot assay was performed to detect T-DM1 degradation. Results We found that intracellular T-DM1 was increased to 50% within 12 h. T-DM1 was colocalized with cholera toxin B (CTxB), a lipid raft marker, within 2 h and then degraded in lysosome. Upon overexpression of caveolin-1 (CAV-1) and utilization of caveolae/lipid-raft disruptors, we found that temporal CAV-1 upregulation significantly facilitated T-DM1 endocytosis and degradation, whereas nystatin and lovastatin disrupted caveolae/lipid-raft structure and inhibited T-DM1 degradation. We demonstrate that T-DM1 internalizes through the lipid raft-mediated endocytosis in a CAV-1 dependent manner, rather than through the clathrin-mediated endocytosis in HER2-positive cancer cells. Conclusion Our findings suggest that modulation of the caveolae/lipid-raft mediated endocytosis may be a possible option for improving the clinical therapeutic effect of T-DM1 because it plays a key role in regulating T-DM1 internalization.
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Affiliation(s)
- Keying Liang
- Department of Biochemistry, Cancer Institute of the Second Affiliated Hospital (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Shengsheng Mei
- Department of Biochemistry, Cancer Institute of the Second Affiliated Hospital (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Xiangzheng Gao
- Department of Biochemistry, Cancer Institute of the Second Affiliated Hospital (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Shanshan Peng
- Department of Biochemistry, Cancer Institute of the Second Affiliated Hospital (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Jinbiao Zhan
- Department of Biochemistry, Cancer Institute of the Second Affiliated Hospital (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
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Deo N, Redpath G. Serotonin Receptor and Transporter Endocytosis Is an Important Factor in the Cellular Basis of Depression and Anxiety. Front Cell Neurosci 2022; 15:804592. [PMID: 35280519 PMCID: PMC8912961 DOI: 10.3389/fncel.2021.804592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Depression and anxiety are common, debilitating psychiatric conditions affecting millions of people throughout the world. Current treatments revolve around selective serotonin reuptake inhibitors (SSRIs), yet these drugs are only moderately effective at relieving depression. Moreover, up to 30% of sufferers are SSRI non-responders. Endocytosis, the process by which plasma membrane and extracellular constituents are internalized into the cell, plays a central role in the regulation of serotonin (5-hydroxytryptophan, 5-HT) signaling, SSRI function and depression and anxiety pathogenesis. Despite their therapeutic potential, surprisingly little is known about the endocytosis of the serotonin receptors (5-HT receptors) or the serotonin transporter (SERT). A subset of 5-HT receptors are endocytosed by clathrin-mediated endocytosis following serotonin binding, while for the majority of 5-HT receptors the endocytic regulation is not known. SERT internalizes serotonin from the extracellular space into the cell to limit the availability of serotonin for receptor binding and signaling. Endocytosis of SERT reduces serotonin uptake, facilitating serotonin signaling. SSRIs predominantly inhibit SERT, preventing serotonin uptake to enhance 5-HT receptor signaling, while hallucinogenic compounds directly activate specific 5-HT receptors, altering their interaction with endocytic adaptor proteins to induce alternate signaling outcomes. Further, multiple polymorphisms and transcriptional/proteomic alterations have been linked to depression, anxiety, and SSRI non-response. In this review, we detail the endocytic regulation of 5-HT receptors and SERT and outline how SSRIs and hallucinogenic compounds modulate serotonin signaling through endocytosis. Finally, we will examine the deregulated proteomes in depression and anxiety and link these with 5-HT receptor and SERT endocytosis. Ultimately, in attempting to integrate the current studies on the cellular biology of depression and anxiety, we propose that endocytosis is an important factor in the cellular basis of depression and anxiety. We will highlight how a thorough understanding 5-HT receptor and SERT endocytosis is integral to understanding the biological basis of depression and anxiety, and to facilitate the development of a next generation of specific, efficacious antidepressant treatments.
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Affiliation(s)
- Nikita Deo
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Gregory Redpath
- European Molecular Biology Lab (EMBL) Australia Node in Single Molecule Science, School of Medical Sciences and the Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW, Australia
- *Correspondence: Gregory Redpath
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Wang S, Liu H, Roberts JB, Wiley AP, Marayati BF, Adams KL, Luessen DJ, Eldeeb K, Sun H, Zhang K, Chen R. Prolonged ethanol exposure modulates constitutive internalization and recycling of 5-HT1A receptors. J Neurochem 2022; 160:469-481. [PMID: 34928513 PMCID: PMC8828711 DOI: 10.1111/jnc.15564] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 11/24/2021] [Accepted: 12/13/2021] [Indexed: 02/03/2023]
Abstract
Alcohol exposure alters the signaling of the serotoninergic system, which is involved in alcohol consumption, reward, and dependence. In particular, dysregulation of serotonin receptor type 1A (5-HT1AR) is associated with alcohol intake and withdrawal-induced anxiety-like behavior in rodents. However, how ethanol regulates 5-HT1AR activity and cell surface availability remains elusive. Using neuroblastoma 2a cells stably expressing human 5-HT1ARs tagged with hemagglutinin at the N-terminus, we found that prolonged ethanol exposure (18 h) reduced the basal surface levels of 5-HT1ARs in a concentration-dependent manner. This reduction is attributed to both enhanced receptor internalization and attenuated receptor recycling. Moreover, constitutive 5-HT1AR internalization in ethanol naïve cells was blocked by concanavalin A (ConA) but not nystatin, suggesting clathrin-dependent 5-HT1AR internalization. In contrast, constitutive 5-HT1AR internalization in ethanol-treated cells was blocked by nystatin but not by ConA, indicating that constitutive 5-HT1AR internalization switched from a clathrin- to a caveolin-dependent pathway. Dynasore, an inhibitor of dynamin, blocked 5-HT1AR internalization in both vehicle- and ethanol-treated cells. Furthermore, ethanol exposure enhanced the activity of dynamin I via dephosphorylation and reduced myosin Va levels, which may contribute to increased internalization and reduced recycling of 5-HT1ARs, respectively. Our findings suggest that prolonged ethanol exposure not only alters the endocytic trafficking of 5-HT1ARs but also the mechanism by which constitutive 5-HT1AR internalization occurs.
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Affiliation(s)
- Shiyu Wang
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
| | - Haoran Liu
- Department of Biology, Wake Forest University, Winston Salem, NC 27106
| | - Jonté B. Roberts
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
| | - Aidan P. Wiley
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
| | | | - Kristen L. Adams
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
| | - Deborah J. Luessen
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
| | - Khalil Eldeeb
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
- Campbell University School of Osteopathic Medicine, Lillington, NC 27546
| | - Haiguo Sun
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
| | - Ke Zhang
- Department of Biology, Wake Forest University, Winston Salem, NC 27106
- Center for Molecular Signaling, Wake Forest University, Winston Salem, NC 27106
| | - Rong Chen
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157
- Center for Molecular Signaling, Wake Forest University, Winston Salem, NC 27106
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Perez-Gil J, Watts A. Translational Biophysics - 20 th IUPAB Congress Session Commentary. Biophys Rev 2021; 13:875-877. [PMID: 34815814 PMCID: PMC8601867 DOI: 10.1007/s12551-021-00867-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 10/22/2021] [Indexed: 01/15/2023] Open
Affiliation(s)
- Jesus Perez-Gil
- Facultad de Biología, Dpto. Bioquímica y Biología Molecular, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Anthony Watts
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU UK
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13
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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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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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15
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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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16
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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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17
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Zou C, Huang X, Lan X, Huang X, Feng Y, Huang J, Meng L, Jian C, Zou D, Wang J, Li X. Potential Genes and Mechanisms Linking Intracerebral Hemorrhage and Depression: A Bioinformatics-Based Study. Int J Gen Med 2021; 14:1213-1226. [PMID: 33854363 PMCID: PMC8039224 DOI: 10.2147/ijgm.s302916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/17/2021] [Indexed: 12/16/2022] Open
Abstract
Purpose The purpose of this study was to investigate the potential pathogenic mechanisms of post-intracerebral hemorrhage depression. Methods Profiles of gene expression in brain tissue of patients with intracerebral hemorrhage (ICH) or depression were downloaded from the Gene Expression Omnibus (GEO) database. We analyzed differentially expressed genes (DEGs) for the two diseases separately. With these DEGs, we conducted an enrichment analysis based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) as well as cross-talk analysis, then we identified hub bridge genes using integrated bridge landscape analysis. Results We found 131 DEGs for interaction between ICH and depression. In the enrichment analysis, we found 55 GO terms and KEGG pathways involving interacting genes of ICH and depression, and 10 GO terms and 10 KEGG pathways most significantly related to cross-talk between ICH and depression. In the integrated bridge landscape analysis, we identified 20 hub bridge genes. In further analysis, we found that hub bridge genes HLA-A, HMOX1, and JUN related to endocytosis, cell adhesion, and phagosomes may exert their effects through the dopamine (DA) system and the serotonergic pathway post-ICH depression. HLA-A may play a role in the occurrence and development of ICH and depression through immune mediation and cell adhesion. HMOX1 and JUN may participate in the mechanism by interacting with HLA-A. Conclusion Through bioinformatics analysis, we identified potential hub bridge genes and pathways related to post-ICH depression. Our study provides references for further research on mechanisms on the pathogenesis of post-ICH depression.
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Affiliation(s)
- Cuihua Zou
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China.,Department of Neurology, Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Xiaohua Huang
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China.,Department of Neurology, Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Xuequn Lan
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Xiaorui Huang
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Yun Feng
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Jianmin Huang
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Lanqing Meng
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Chongdong Jian
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Donghua Zou
- Department of Neurology, The Fifth Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, 530022, People's Republic of China
| | - Jie Wang
- Department of Nephrology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
| | - Xuebin Li
- Department of Neurology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China.,Department of Neurology, Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China
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18
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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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19
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Martínez-Aguirre C, Carmona-Cruz F, Velasco AL, Velasco F, Aguado-Carrillo G, Cuéllar-Herrera M, Rocha L. Cannabidiol Acts at 5-HT 1A Receptors in the Human Brain: Relevance for Treating Temporal Lobe Epilepsy. Front Behav Neurosci 2020; 14:611278. [PMID: 33384591 PMCID: PMC7770178 DOI: 10.3389/fnbeh.2020.611278] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/23/2020] [Indexed: 12/29/2022] Open
Abstract
Experimental evidence indicates that cannabidiol (CBD) induces anxiolytic and antiepileptic effects through the activation of 5-HT1A receptors. These receptors are coupled to Gi/o proteins and induce inhibitory effects. At present, the interaction of CBD with 5-HT1A receptors in the human brain is unknown. The aim of this study focused on evaluating the interaction between CBD and 5-HT1A receptors in cell membranes obtained from the hippocampus and temporal neocortex of autopsies and patients with drug-resistant mesial temporal lobe epilepsy (DR-MTLE). Cell membranes were isolated from the hippocampus and temporal neocortex of a group of patients with DR-MTLE who were submitted to epilepsy surgery (n = 11) and from a group of autopsies (n = 11). The [3H]-8-OH-DPAT binding assay was used to determine the pharmacological interaction of CBD with 5-HT1A receptors. The [35S]-GTPγS assay was used to investigate the CBD-induced activation of Gi/o proteins through its action on 5-HT1A receptors.The CBD affinity (pK i) for 5-HT1A receptors was similar for autopsies and patients with DR-MTLE (hippocampus: 4.29 and 4.47, respectively; temporal neocortex: 4.67 and 4.74, respectively). Concerning the [35S]-GTPγS assay, no statistically significant changes were observed for both hippocampal and neocortical tissue (p > 0.05) at low CBD concentrations (1 pM to 10 μM). In contrast, at high concentrations (100 μM), CBD reduced the constitutive activity of Gi/o proteins of autopsies and DR-MTLE patients (hippocampus: 39.2% and 39.6%, respectively; temporal neocortex: 35.2% and 24.4%, respectively). These changes were partially reversed in the presence of WAY-100635, an antagonist of 5-HT1A receptors, in the autopsy group (hippocampus, 59.8%, p < 0.0001; temporal neocortex, 71.5%, p < 0.0001) and the group of patients with DR-MTLE (hippocampus, 53.7%, p < 0.0001; temporal neocortex, 68.5%, p < 0.001). Our results show that CBD interacts with human 5-HT1A receptors of the hippocampus and temporal neocortex. At low concentrations, the effect of CBD upon Gi/o protein activation is limited. However, at high concentrations, CBD acts as an inverse agonist of 5-HT1A receptors. This effect could modify neuronal excitation and epileptic seizures in patients with DR-MTLE.
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Affiliation(s)
| | - Francia Carmona-Cruz
- Department of Pharmacobiology, Center for Research and Advanced Studies, Mexico City, Mexico
| | - Ana Luisa Velasco
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico
| | - Francisco Velasco
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico
| | | | | | - Luisa Rocha
- Department of Pharmacobiology, Center for Research and Advanced Studies, Mexico City, Mexico
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20
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Lesiak L, Zhou X, Fang Y, Zhao J, Beck JR, Stains CI. Imaging GPCR internalization using near-infrared Nebraska red-based reagents. Org Biomol Chem 2020; 18:2459-2467. [PMID: 32167123 DOI: 10.1039/d0ob00043d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Internalization of G protein-coupled receptor (GPCRs) represents a nearly universal pathway for receptor downregulation. Imaging this process provides a means for the identification of pharmaceutical agents as well as potential ligands for orphan receptors. However, there is a need for the further development of near-infrared (NIR) probes capable of monitoring internalization in order to enable multiplexing with existing green fluorescent GPCR activity assays. Our laboratory has recently described a series of near-infrared (NIR) fluorophores in which a phosphinate functionality is inserted at the bridging position of the xanthene scaffold. These fluorophores, termed Nebraska Red (NR) dyes, provide attractive reagents for imaging protein localization. Herein, we disclose the development of NR-based HaloTag ligands for imaging membrane proteins on living cells. These new probes are utilized to image membrane pools of the human orexin type 2 receptor, an established target for the treatment of insomnia. We demonstrate the ability of fetal bovine serum (FBS) to noncovalently associate with a spirolactonized NR probe, enabling no-wash imaging with a 45-fold enhancement of fluorescence. Furthermore, we characterize the utility of NR-based HaloTag ligands for real-time monitoring of receptor internalization upon agonist stimulation. These new reagents enable potential multiplexing with existing GPCR activity assays in order to identify new modulators of GPCR activity as well as ligands for orphan receptors.
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Affiliation(s)
- Lauren Lesiak
- Department of Chemistry, University of Nebraska - Lincoln, Lincoln, NE 68588, USA.
| | - Xinqi Zhou
- Department of Chemistry, University of Nebraska - Lincoln, Lincoln, NE 68588, USA.
| | - Yuan Fang
- Department of Chemistry, University of Nebraska - Lincoln, Lincoln, NE 68588, USA. and Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Jia Zhao
- Department of Chemistry, University of Nebraska - Lincoln, Lincoln, NE 68588, USA.
| | - Jon R Beck
- Department of Chemistry, University of Nebraska - Lincoln, Lincoln, NE 68588, USA.
| | - Cliff I Stains
- Department of Chemistry, University of Nebraska - Lincoln, Lincoln, NE 68588, USA. and Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA and Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE 68588, USA and Cancer Genes and Molecular Regulation Program, Fred & Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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21
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Sarkar P, Mozumder S, Bej A, Mukherjee S, Sengupta J, Chattopadhyay A. Structure, dynamics and lipid interactions of serotonin receptors: excitements and challenges. Biophys Rev 2020; 13:10.1007/s12551-020-00772-8. [PMID: 33188638 PMCID: PMC7930197 DOI: 10.1007/s12551-020-00772-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/05/2020] [Indexed: 12/13/2022] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is an intrinsically fluorescent neurotransmitter found in organisms spanning a wide evolutionary range. Serotonin exerts its diverse actions by binding to distinct cell membrane receptors which are classified into many groups. Serotonin receptors are involved in regulating a diverse array of physiological signaling pathways and belong to the family of either G protein-coupled receptors (GPCRs) or ligand-gated ion channels. Serotonergic signaling appears to play a key role in the generation and modulation of various cognitive and behavioral functions such as sleep, mood, pain, anxiety, depression, aggression, and learning. Serotonin receptors act as drug targets for a number of diseases, particularly neuropsychiatric disorders. The signaling mechanism and efficiency of serotonin receptors depend on their amazing ability to rapidly access multiple conformational states. This conformational plasticity, necessary for the wide variety of functions displayed by serotonin receptors, is regulated by binding to various ligands. In this review, we provide a succinct overview of recent developments in generating and analyzing high-resolution structures of serotonin receptors obtained using crystallography and cryo-electron microscopy. Capturing structures of distinct conformational states is crucial for understanding the mechanism of action of these receptors, which could provide important insight for rational drug design targeting serotonin receptors. We further provide emerging information and insight from studies on interactions of membrane lipids (such as cholesterol) with serotonin receptors. We envision that a judicious combination of analysis of high-resolution structures and receptor-lipid interaction would allow a comprehensive understanding of GPCR structure, function and dynamics, thereby leading to efficient drug discovery.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
| | - Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201 002, India
| | - Aritra Bej
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
| | - Sujoy Mukherjee
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201 002, India
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22
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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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23
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Shrivastava S, Sarkar P, Preira P, Salomé L, Chattopadhyay A. Role of Actin Cytoskeleton in Dynamics and Function of the Serotonin 1A Receptor. Biophys J 2019; 118:944-956. [PMID: 31606121 DOI: 10.1016/j.bpj.2019.08.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/13/2019] [Accepted: 08/29/2019] [Indexed: 12/19/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are important membrane proteins in higher eukaryotes that carry out a vast array of cellular signaling and act as major drug targets. The serotonin1A receptor is a prototypical member of the GPCR family and is implicated in neuropsychiatric disorders such as anxiety and depression, besides serving as an important drug target. With an overall goal of exploring the functional consequence of altered receptor dynamics, in this work, we probed the role of the actin cytoskeleton in the dynamics, ligand binding, and signaling of the serotonin1A receptor. We monitored receptor dynamics utilizing single particle tracking, which provides information on relative distribution of receptors in various diffusion modes in addition to diffusion coefficient. We show here that the short-term diffusion coefficient of the receptor increases upon actin destabilization by cytochalasin D. In addition, analysis of individual trajectories shows that there are changes in relative populations of receptors undergoing various types of diffusion upon actin destabilization. The release of dynamic constraint was evident by an increase in the radius of confinement of the receptor upon actin destabilization. The functional implication of such actin destabilization was manifested as an increase in specific agonist binding and downstream signaling, monitored by measuring reduction in cellular cAMP levels. These results bring out the interdependence of GPCR dynamics with cellular signaling.
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Affiliation(s)
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Pascal Preira
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Laurence Salomé
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France.
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