1
|
Chintala SM, Tateiwa H, Qian M, Xu Y, Amtashar F, Chen ZW, Kirkpatrick CC, Bracamontes J, Germann AL, Akk G, Covey DF, Evers AS. Direct measurements of neurosteroid binding to specific sites on GABA A receptors. Br J Pharmacol 2024; 181:4229-4244. [PMID: 38978389 DOI: 10.1111/bph.16490] [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: 08/08/2023] [Revised: 05/12/2024] [Accepted: 05/30/2024] [Indexed: 07/10/2024] Open
Abstract
BACKGROUND AND PURPOSE Neurosteroids are allosteric modulators of GABAA currents, acting through several functional binding sites although their affinity and specificity for each site are unknown. The goal of this study was to measure steady-state binding affinities of various neurosteroids for specific sites on the GABAA receptor. EXPERIMENTAL APPROACH Two methods were developed to measure neurosteroid binding affinity: (1) quenching of specific tryptophan residues in neurosteroid binding sites by the neurosteroid 17-methylketone group, and (2) FRET between MQ290 (an intrinsically fluorescent neurosteroid) and tryptophan residues in the binding sites. The assays were developed using ELIC-α1GABAAR, a chimeric receptor containing transmembrane domains of the α1-GABAA receptor. Tryptophan mutagenesis was used to identify specific interactions. KEY RESULTS Allopregnanolone (3α-OH neurosteroid) was shown to bind at intersubunit and intrasubunit sites with equal affinity, whereas epi-allopregnanolone (3β-OH neurosteroid) binds at the intrasubunit site. MQ290 formed a strong FRET pair with W246, acting as a site-specific probe for the intersubunit site. The affinity and site-specificity of several neurosteroid agonists and inverse agonists was measured using the MQ290 binding assay. The FRET assay distinguishes between competitive and allosteric inhibition of MQ290 binding and demonstrated an allosteric interaction between the two neurosteroid binding sites. CONCLUSIONS AND IMPLICATIONS The affinity and specificity of neurosteroid binding to two sites in the ELIC-α1GABAAR were directly measured and an allosteric interaction between the sites was revealed. Adaptation of the MQ290 FRET assay to a plate-reader format will enable screening for high affinity agonists and antagonists for neurosteroid binding sites.
Collapse
Affiliation(s)
- Satyanarayana M Chintala
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Hiroki Tateiwa
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
| | - Mingxing Qian
- Department of Developmental Biology (Pharmacology), Washington University School of Medicine, St. Louis, Missouri, USA
| | - Yuanjian Xu
- Department of Developmental Biology (Pharmacology), Washington University School of Medicine, St. Louis, Missouri, USA
| | - Fatima Amtashar
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
| | | | - John Bracamontes
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Allison L Germann
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Gustav Akk
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
| | - Douglas F Covey
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alex S Evers
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
- Taylor Family Institute for Innovative Psychiatric Research, St. Louis, Missouri, USA
| |
Collapse
|
2
|
Ma M, Xu H, Ye L, Li C, Zhu H, Jiang W, Wang W, Yang H, Yang Y, Wang Y, Tian J. Synthesis and evaluation of neuroactive steroids with novel pharmacophore at C-21 let identify a compound with advantageous PK profile and higher EC 50 and E max as PAM on GABAA receptor. Eur J Med Chem 2024; 276:116602. [PMID: 38971049 DOI: 10.1016/j.ejmech.2024.116602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/03/2024] [Accepted: 06/13/2024] [Indexed: 07/08/2024]
Abstract
Zuranolone (SAGE-217) is a neuroactive steroid (γ-aminobutyric acid)A (GABAA) receptor positive allosteric modulator (PAM) as the first oral drug approved by the FDA in 2023, which is used to treat patients with postpartum depression (PPD). SAGE-217 has a "black box" warning with impairing ability to drive or engage in other potentially hazardous activities. In addition, SAGE-217 can cause CNS depressant effects such as somnolence and confusion, suicidal thoughts and behavior and embryo-fetal toxicity. Based on the structure-activity relationship (SAR) of SAGE-217, a total of 28 neuroactive steroids with novel pharmacophore at C-21 modulated SAGE-217 derivatives were designed and synthesized. The biological activities were evaluated by both synaptic α1β2γ2 GABAA receptor and extrasynaptic α4β3δ GABAA receptor cell assays. The optimal compound S28 exhibited much more potent potency and similar efficacy at extrasynaptic GABAA receptor than SAGE-217. Different from above, compound S28 exhibited similar potency and lower efficacy at synaptic GABAA receptor than SAGE-217, which were consistent with the analysis of molecular docking and dynamics simulation results. The appropriate lower efficacy at synaptic GABAA receptor of compound S28 might contribute to reduce the side effects of excessive sedation. Furthermore, compound S28 was demonstrated to have excellent in vivo pharmacokinetic (PK) parameters, robust in vivo pharmacodynamic (PD) effects and good safety profiles. Therefore, compound S28 represents a potentially promising treatment of PPD candidate that warrants further investigation.
Collapse
Affiliation(s)
- Mingxu Ma
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Hengwei Xu
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Liang Ye
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China; School of Public Health and Management, Binzhou Medical University, Yantai, 256603, China
| | - Chunmei Li
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Haibo Zhu
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China; School of Public Health and Management, Binzhou Medical University, Yantai, 256603, China
| | - Wanglin Jiang
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China; School of Pharmacy, Binzhou Medical University, Yantai, 256603, China
| | - Wenyan Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Huijie Yang
- State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Yingjie Yang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Yao Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China
| | - Jingwei Tian
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, 264005, China; State Key Laboratory of Advanced Drug Delivery and Release Systems, Shandong Luye Pharmaceutical Co., Ltd., Yantai, Shandong, 264003, China.
| |
Collapse
|
3
|
Gonda X, Tarazi FI, Dome P. The emergence of antidepressant drugs targeting GABA A receptors: A concise review. Biochem Pharmacol 2024; 228:116481. [PMID: 39147329 DOI: 10.1016/j.bcp.2024.116481] [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: 05/21/2024] [Revised: 08/06/2024] [Accepted: 08/09/2024] [Indexed: 08/17/2024]
Abstract
Depression is among the most common psychiatric illnesses, which imposes a major socioeconomic burden on patients, caregivers, and the public health system. Treatment with classical antidepressants (e.g. tricyclic antidepressants and selective serotonine reuptake inhibitors), which primarily affect monoaminergic systems has several limitations, such as delayed onset of action and moderate efficacy in a relatively large proportion of depressed patients. Furthermore, depression is highly heterogeneus, and its different subtypes, including post-partum depression, involve distinct neurobiology, warranting a differential approach to pharmacotherapy. Given these shortcomings, the need for novel antidepressants that are superior in efficacy and faster in onset of action is fully justified. The development and market introduction of rapid-acting antidepressants has accelerated in recent years. Some of these new antidepressants act through the GABAergic system. In this review, we discuss the discovery, efficacy, and limitations of treatment with classic antidepressants. We provide a detailed discussion of GABAergic neurotransmission, with a special focus on GABAA receptors, and possible explanations for the mood-enhancing effects of GABAergic medications (in particular neurosteroids acting at GABAA receptors), and, ultimately, we present the most promising molecules belonging to this family which are currently used in clinical practice or are in late phases of clinical development.
Collapse
Affiliation(s)
- Xenia Gonda
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary; NAP3.0-SE Neuropsychopharmacology Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary.
| | - Frank I Tarazi
- Department of Psychiatry and Neurology, Harvard Medical School and McLean Hospital, Boston, MA, USA
| | - Peter Dome
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary; Nyiro Gyula National Institute of Psychiatry and Addictology, Budapest, Hungary
| |
Collapse
|
4
|
Kan C, Ullah A, Dang S, Xue H. Modular Structure and Polymerization Status of GABA A Receptors Illustrated with EM Analysis and AlphaFold2 Prediction. Int J Mol Sci 2024; 25:10142. [PMID: 39337627 PMCID: PMC11432007 DOI: 10.3390/ijms251810142] [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: 06/29/2024] [Revised: 08/31/2024] [Accepted: 09/18/2024] [Indexed: 09/30/2024] Open
Abstract
Type-A γ-aminobutyric acid (GABAA) receptors are channel proteins crucial to mediating neuronal balance in the central nervous system (CNS). The structure of GABAA receptors allows for multiple binding sites and is key to drug development. Yet the formation mechanism of the receptor's distinctive pentameric structure is still unknown. This study aims to investigate the role of three predominant subunits of the human GABAA receptor in the formation of protein pentamers. Through purifying and refolding the protein fragments of the GABAA receptor α1, β2, and γ2 subunits, the particle structures were visualised with negative staining electron microscopy (EM). To aid the analysis, AlphaFold2 was used to compare the structures. Results show that α1 and β2 subunit fragments successfully formed homo-oligomers, particularly homopentameric structures, while the predominant heteropentameric GABAA receptor was also replicated through the combination of the three subunits. However, homopentameric structures were not observed with the γ2 subunit proteins. A comparison of the AlphaFold2 predictions and the previously obtained cryo-EM structures presents new insights into the subunits' modular structure and polymerization status. By performing experimental and computational studies, a deeper understanding of the complex structure of GABAA receptors is provided. Hopefully, this study can pave the way to developing novel therapeutics for neuropsychiatric diseases.
Collapse
Affiliation(s)
| | | | | | - Hong Xue
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; (C.K.); (A.U.); (S.D.)
| |
Collapse
|
5
|
Chen ZW, Chintala SM, Bracamontes J, Sugasawa Y, Pierce SR, Varga BR, Smith EH, Edge CJ, Franks NP, Cheng WWL, Akk G, Evers AS. Three classes of propofol binding sites on GABA A receptors. J Biol Chem 2024; 300:107778. [PMID: 39270821 DOI: 10.1016/j.jbc.2024.107778] [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: 01/09/2024] [Revised: 09/04/2024] [Accepted: 09/06/2024] [Indexed: 09/15/2024] Open
Abstract
Propofol is a widely used anesthetic and sedative that acts as a positive allosteric modulator of gamma-aminobutyric acid type A (GABAA) receptors. Several potential propofol binding sites that may mediate this effect have been identified using propofol-analogue photoaffinity labeling. Ortho-propofol diazirine (o-PD) labels β-H267, a pore-lining residue, whereas AziPm labels residues β-M286, β-M227, and α-I239 in the two membrane-facing interfaces [β(+)/α(-) and α(+)/β(-)] between α and β subunits. This study used photoaffinity labeling of α1β3 GABAA receptors to reconcile the apparently conflicting results obtained with AziPm and o-PD labeling, focusing on whether β3-H267 identifies specific propofol binding site(s). The results show that propofol, but not AziPm protects β3-H267 from labeling by o-PD, whereas both propofol and o-PD protect against AziPm labeling of β3-M286, β3-M227, and α1I239. These data indicate that there are three distinct classes of propofol binding sites, with AziPm binding to two of the classes and o-PD to all three. Analysis of binding stoichiometry using native mass spectrometry in β3 homomeric receptors, demonstrated a minimum of five AziPm labeled residues and three o-PD labeled residues per pentamer, suggesting that there are two distinct propofol binding sites per β-subunit. The native mass spectrometry data, coupled with photolabeling performed in the presence of zinc, indicate that the binding site(s) identified by o-PD are adjacent to, but not within the channel pore, since the pore at the 17' H267 residue can accommodate only one propofol molecule. These data validate the existence of three classes of specific propofol binding sites on α1β3 GABAA receptors.
Collapse
Affiliation(s)
- Zi-Wei Chen
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; The Taylor Family Institute for Innovative Psychiatric Research Washington University School of Medicine, St Louis, Missouri, USA
| | | | - John Bracamontes
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Yusuke Sugasawa
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan
| | - Spencer R Pierce
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Balazs R Varga
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Edward H Smith
- Department of Life Sciences, Imperial College, London, UK
| | | | - Nicholas P Franks
- Department of Life Sciences, Imperial College, London, UK; UK Dementia Research Institute, Imperial College, London, UK
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Gustav Akk
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; The Taylor Family Institute for Innovative Psychiatric Research Washington University School of Medicine, St Louis, Missouri, USA
| | - Alex S Evers
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Developmental Biology, Washington University School of Medicine, St Louis, Missouri, USA; The Taylor Family Institute for Innovative Psychiatric Research Washington University School of Medicine, St Louis, Missouri, USA.
| |
Collapse
|
6
|
Fan C, Cowgill J, Howard RJ, Lindahl E. Divergent mechanisms of steroid inhibition in the human ρ1 GABA A receptor. Nat Commun 2024; 15:7795. [PMID: 39242530 PMCID: PMC11379708 DOI: 10.1038/s41467-024-51904-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 08/19/2024] [Indexed: 09/09/2024] Open
Abstract
ρ-type γ-aminobutyric acid-A (GABAA) receptors are widely distributed in the retina and brain, and are potential drug targets for the treatment of visual, sleep and cognitive disorders. Endogenous neuroactive steroids including β-estradiol and pregnenolone sulfate negatively modulate the function of ρ1 GABAA receptors, but their inhibitory mechanisms are not clear. By combining five cryo-EM structures with electrophysiology and molecular dynamics simulations, we characterize binding sites and negative modulation mechanisms of β-estradiol and pregnenolone sulfate at the human ρ1 GABAA receptor. β-estradiol binds in a pocket at the interface between extracellular and transmembrane domains, apparently specific to the ρ subfamily, and disturbs allosteric conformational transitions linking GABA binding to pore opening. In contrast, pregnenolone sulfate binds inside the pore to block ion permeation, with a preference for activated structures. These results illuminate contrasting mechanisms of ρ1 inhibition by two different neuroactive steroids, with potential implications for subtype-specific gating and pharmacological design.
Collapse
Affiliation(s)
- Chen Fan
- Dept. of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - John Cowgill
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Rebecca J Howard
- Dept. of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden.
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden.
| | - Erik Lindahl
- Dept. of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden.
- Dept. of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden.
| |
Collapse
|
7
|
De Lellis LF, Morone MV, Buccato DG, Cordara M, Larsen DS, Ullah H, Piccinocchi R, Piccinocchi G, Balaji P, Baldi A, Di Minno A, El-Seedi HR, Sacchi R, Daglia M. Efficacy of Food Supplement Based on Monacolins, γ-Oryzanol, and γ-Aminobutyric Acid in Mild Dyslipidemia: A Randomized, Double-Blind, Parallel-Armed, Placebo-Controlled Clinical Trial. Nutrients 2024; 16:2983. [PMID: 39275298 PMCID: PMC11397197 DOI: 10.3390/nu16172983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2024] [Revised: 08/24/2024] [Accepted: 08/31/2024] [Indexed: 09/16/2024] Open
Abstract
The risk of cardiovascular disease (CVD) is approximately doubled in subjects with hypercholesterolemia compared to those with normal blood cholesterol levels. Monacolin K (MK), the main active substance in rice fermented by the Monascus purpureus, acts on cholesterol metabolism. Rice also contains other bioactive compounds such as γ-oryzanol (OZ) and γ-aminobutyric acid (GABA). In a randomized, placebo-controlled, double-blind trial, the efficacy and tolerability of a food supplement (FS) based on an ingredient standardized to contain monacolins (4.5%), OZ, and GABA were evaluated in subjects with mild dyslipidemia. For the duration of the trial, enrolled subjects (n = 44, each group) received the FS or placebo and were instructed to use an isocaloric diet. Compared to the placebo group, after a 3 months of the FS, the mean low-density lipoprotein cholesterol and mean TC values were reduced by 19.3 and 8.3%, respectively, while the mean high-density lipoprotein cholesterol value increased by 29.3%. On average, the subjects shifted from very high to moderate CVD risk. Glucose metabolism and hepatic and renal parameters did not change after the treatment and no adverse events were reported. Guidelines to handle hypercholesterolemia with food supplements in specific clinical settings are needed to better manage mild dyslipidemia.
Collapse
Affiliation(s)
| | - Maria Vittoria Morone
- Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, University of Campania "L. Vanvitelli", 80138 Naples, Italy
| | - Daniele Giuseppe Buccato
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
| | - Marcello Cordara
- School of Medicine, University of Milano-Bicocca, 20126 Milan, Italy
| | - Danaè S Larsen
- School of Chemical Sciences, The University of Auckland, Auckland 1010, New Zealand
| | - Hammad Ullah
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
| | - Roberto Piccinocchi
- Level 1 Medical Director Anaesthesia and Resuscitation A. U. O. Luigi Vanvitelli, Via Santa Maria di Costantinopoli, 80138 Naples, Italy
| | - Gaetano Piccinocchi
- Comegen S.c.S., Società Cooperativa Sociale di Medici di Medicina Generale, Viale Maria Bakunin 41, 80125 Naples, Italy
| | - Paulraj Balaji
- PG and Research Centre in Biotechnology, MGR College, Hosur 635130, TN, India
| | - Alessandra Baldi
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
| | - Alessandro Di Minno
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate, Via Gaetano Salvatore 486, 80145 Naples, Italy
| | - Hesham R El-Seedi
- Department of Chemistry, Faculty of Science, Islamic University of Madinah, Madinah 42351, Saudi Arabia
| | - Roberto Sacchi
- Applied Statistic Unit, Department of Earth and Environmental Sciences, University of Pavia, Viale Taramelli 24, 27100 Pavia, Italy
| | - Maria Daglia
- Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
- International Research Center for Food Nutrition and Safety, Jiangsu University, Zhenjiang 212013, China
| |
Collapse
|
8
|
Romero-Ramírez L, Mey J. Emerging Roles of Bile Acids and TGR5 in the Central Nervous System: Molecular Functions and Therapeutic Implications. Int J Mol Sci 2024; 25:9279. [PMID: 39273226 PMCID: PMC11395147 DOI: 10.3390/ijms25179279] [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: 07/31/2024] [Revised: 08/15/2024] [Accepted: 08/17/2024] [Indexed: 09/15/2024] Open
Abstract
Bile acids (BAs) are cholesterol derivatives synthesized in the liver and released into the digestive tract to facilitate lipid uptake during the digestion process. Most of these BAs are reabsorbed and recycled back to the liver. Some of these BAs progress to other tissues through the bloodstream. The presence of BAs in the central nervous system (CNS) has been related to their capacity to cross the blood-brain barrier (BBB) from the systemic circulation. However, the expression of enzymes and receptors involved in their synthesis and signaling, respectively, support the hypothesis that there is an endogenous source of BAs with a specific function in the CNS. Over the last decades, BAs have been tested as treatments for many CNS pathologies, with beneficial effects. Although they were initially reported as neuroprotective substances, they are also known to reduce inflammatory processes. Most of these effects have been related to the activation of the Takeda G protein-coupled receptor 5 (TGR5). This review addresses the new challenges that face BA research for neuroscience, focusing on their molecular functions. We discuss their endogenous and exogenous sources in the CNS, their signaling through the TGR5 receptor, and their mechanisms of action as potential therapeutics for neuropathologies.
Collapse
Affiliation(s)
- Lorenzo Romero-Ramírez
- Laboratorio de Regeneración Neuronal, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain
| | - Jörg Mey
- Laboratorio de Regeneración Neuronal, Hospital Nacional de Parapléjicos, Servicio de Salud de Castilla-La Mancha, 45071 Toledo, Spain
- EURON Graduate School of Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
| |
Collapse
|
9
|
Bennett WFD, Bernardi A, Ozturk TN, Ingólfsson HI, Fox SJ, Sun D, Maupin CM. ezAlign: A Tool for Converting Coarse-Grained Molecular Dynamics Structures to Atomistic Resolution for Multiscale Modeling. Molecules 2024; 29:3557. [PMID: 39124960 PMCID: PMC11314399 DOI: 10.3390/molecules29153557] [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: 06/18/2024] [Revised: 07/22/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
Soft condensed matter is challenging to study due to the vast time and length scales that are necessary to accurately represent complex systems and capture their underlying physics. Multiscale simulations are necessary to study processes that have disparate time and/or length scales, which abound throughout biology and other complex systems. Herein we present ezAlign, an open-source software for converting coarse-grained molecular dynamics structures to atomistic representation, allowing multiscale modeling of biomolecular systems. The ezAlign v1.1 software package is publicly available for download at github.com/LLNL/ezAlign. Its underlying methodology is based on a simple alignment of an atomistic template molecule, followed by position-restraint energy minimization, which forces the atomistic molecule to adopt a conformation consistent with the coarse-grained molecule. The molecules are then combined, solvated, minimized, and equilibrated with position restraints. Validation of the process was conducted on a pure POPC membrane and compared with other popular methods to construct atomistic membranes. Additional examples, including surfactant self-assembly, membrane proteins, and more complex bacterial and human plasma membrane models, are also presented. By providing these examples, parameter files, code, and an easy-to-follow recipe to add new molecules, this work will aid future multiscale modeling efforts.
Collapse
Affiliation(s)
- W. F. Drew Bennett
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.B.); (T.N.O.); (H.I.I.); (D.S.)
| | - Austen Bernardi
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.B.); (T.N.O.); (H.I.I.); (D.S.)
| | - Tugba Nur Ozturk
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.B.); (T.N.O.); (H.I.I.); (D.S.)
| | - Helgi I. Ingólfsson
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.B.); (T.N.O.); (H.I.I.); (D.S.)
| | | | - Delin Sun
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; (A.B.); (T.N.O.); (H.I.I.); (D.S.)
| | - C. Mark Maupin
- Procter and Gamble, Mason, OH 45040, USA;
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
| |
Collapse
|
10
|
Do HQ, Pirayesh E, Ferreira G, Pandhare A, Gallardo ZR, Jansen M. A bupropion modulatory site in the Gloeobacter violaceus ligand-gated ion channel. Biophys J 2024; 123:2185-2198. [PMID: 38678367 PMCID: PMC11309978 DOI: 10.1016/j.bpj.2024.04.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/27/2024] [Accepted: 04/25/2024] [Indexed: 04/29/2024] Open
Abstract
Bupropion is an atypical antidepressant and smoking cessation drug that causes adverse effects such as insomnia, irritability, and anxiety. Bupropion inhibits dopamine and norepinephrine reuptake transporters and eukaryotic cation-conducting pentameric ligand-gated ion channels, such as nicotinic acetylcholine and serotonin type 3A receptors, at clinically relevant concentrations. Here, we demonstrate that bupropion also inhibits a prokaryotic homolog of pentameric ligand-gated ion channels, the Gloeobacter violaceus ligand-gated ion channel (GLIC). Using the GLIC as a model, we used molecular docking to predict binding sites for bupropion. Bupropion was found to bind to several sites within the transmembrane domain, with the predominant site being localized to the interface between transmembrane segments M1 and M3 of two adjacent subunits. Residues W213, T214, and W217 in the first transmembrane segment, M1, and F267 and I271 in the third transmembrane segment, M3, most frequently reside within a 4 Å distance from bupropion. We then used single amino acid substitutions at these positions and two-electrode voltage-clamp recordings to determine their impact on bupropion inhibitory effects. The substitution T214F alters bupropion potency by shifting the half-maximal inhibitory concentration to a 13-fold higher value compared to wild-type GLIC. Residue T214 is found within a previously identified binding pocket for neurosteroids and lipids in the GLIC. This intersubunit binding pocket is structurally conserved and almost identical to a binding pocket described for neurosteroids in γ-aminobutyric acid type A receptors. Our data thus suggest that the T214 that lines a previously identified lipophilic binding pocket in GLIC and γ-aminobutyric acid type A receptors is also a modulatory site for bupropion interaction with the GLIC.
Collapse
Affiliation(s)
- Hoa Quynh Do
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Elham Pirayesh
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Garren Ferreira
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Akash Pandhare
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Zackary Ryan Gallardo
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Michaela Jansen
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas.
| |
Collapse
|
11
|
Chojnacka W, Teng J, Kim JJ, Jensen AA, Hibbs RE. Structural insights into GABA A receptor potentiation by Quaalude. Nat Commun 2024; 15:5244. [PMID: 38898000 PMCID: PMC11187190 DOI: 10.1038/s41467-024-49471-y] [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: 12/08/2023] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
Methaqualone, a quinazolinone marketed commercially as Quaalude, is a central nervous system depressant that was used clinically as a sedative-hypnotic, then became a notorious recreational drug in the 1960s-80s. Due to its high abuse potential, medical use of methaqualone was eventually prohibited, yet it persists as a globally abused substance. Methaqualone principally targets GABAA receptors, which are the major inhibitory neurotransmitter-gated ion channels in the brain. The restricted status and limited accessibility of methaqualone have contributed to its pharmacology being understudied. Here, we use cryo-EM to localize the GABAA receptor binding sites of methaqualone and its more potent derivative, PPTQ, to the same intersubunit transmembrane sites targeted by the general anesthetics propofol and etomidate. Both methaqualone and PPTQ insert more deeply into subunit interfaces than the previously-characterized modulators. Binding of quinazolinones to this site results in widening of the extracellular half of the ion-conducting pore, following a trend among positive allosteric modulators in destabilizing the hydrophobic activation gate in the pore as a mechanism for receptor potentiation. These insights shed light on the underexplored pharmacology of quinazolinones and further elucidate the molecular mechanisms of allosteric GABAA receptor modulation through transmembrane binding sites.
Collapse
Affiliation(s)
- Weronika Chojnacka
- Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA, USA
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Jinfeng Teng
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Jeong Joo Kim
- Protein Structure and Function, Loxo@Lilly, Louisville, CO, USA
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Ryan E Hibbs
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA.
- Department of Pharmacology, University of California San Diego, La Jolla, CA, USA.
| |
Collapse
|
12
|
Mortensen M, Bright DP, Fagotti J, Dorovykh V, Cerna B, Smart TG. Forty Years Searching for Neurosteroid Binding Sites on GABA A Receptors. Neuroscience 2024:S0306-4522(24)00257-4. [PMID: 38852898 DOI: 10.1016/j.neuroscience.2024.06.002] [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: 04/04/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
Brain inhibition is a vital process for controlling and sculpting the excitability of the central nervous system in healthy individuals. This level of control is provided over several timescales and involves the neurotransmitter GABA acting at inhibitory synapses to: rapidly inhibit neurons by activating the GABAA receptor; over a slower timescale, to tonically activate extrasynaptic GABAA receptors to provide a low level of background inhibition; and finally, to activate G-protein coupled GABAB receptors to control transmitter release by inhibiting presynaptic Ca2+ channels whilst providing postsynaptic inhibition via K+ channel activation. From this plethora of roles for GABA and its receptors, the GABAA receptor isoform is of major interest due to its dynamic functional plasticity, which in part, is due to being targeted by modulatory brain neurosteroids derived from sex and stress hormones. This family of neurosteroids can, depending on their structure, potentiate, activate and also inhibit the activity of GABAA receptors to affect brain inhibition. This review tracks the methods that have been deployed in probing GABAA receptors, and charts the sterling efforts made by several groups to locate the key neurosteroid binding sites that affect these important receptors. Increasing our knowledge of these binding sites will greatly facilitate our understanding of the physiological roles of neurosteroids and will help to advance their use as novel therapeutics to combat debilitating brain diseases.
Collapse
Affiliation(s)
- Martin Mortensen
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Damian P Bright
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Juliane Fagotti
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Valentina Dorovykh
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Barbora Cerna
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom
| | - Trevor G Smart
- University College London, Dept Neuroscience, Physiology & Pharmacology, Gower Street, London WC1E 6BT, United Kingdom.
| |
Collapse
|
13
|
Bukanova JV, Solntseva EI, Skrebitsky VG. Factors promoting the release of picrotoxin from the trap in the GABA(A) receptor pore. Neurochem Int 2024; 175:105703. [PMID: 38395151 DOI: 10.1016/j.neuint.2024.105703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/31/2024] [Accepted: 02/21/2024] [Indexed: 02/25/2024]
Abstract
Picrotoxin (PTX), a convulsant of plant origin, has been used in many studies as research tool. PTX is the open channel blocker of the GABAA receptor (GABAAR). Being in the pore, PTX initiates transfer of the channel to the closed state and thus it falls into the "trap". The consequence of this PTX trapping is so-called aftereffect, i.e. continuation of the blockade of the GABA-induced chloride current (IGABA) after removal of PTX from the external solution. The present work shows that the positive allosteric modulators (PAMs) of the GABAA receptor, allopregnanolone (Allo) and zolpidem (Zolp) as well as a high concentration of GABA shortened the PTX aftereffect. Experiments were carried out on isolated Purkinje neurons of the rat cerebellum using the whole-cell patch-clamp method. IGABA was induced by applications of 5 μM GABA (EC30) for 1 s with 30 s intervals. 50 μM PTX completely blocked IGABA, and recovery upon PTX washout occurred with a time constant (τrec) of 20.2 min. 1 μM Allo reduced the blocking effect of PTX by 30% and accelerated the recovery of IGABA by almost 10 times (τrec = 2.4 min). 0.5 μM Zolp did not change the IGABA block in the presence of PTX but accelerated the recovery of IGABA by more than 3 times (τrec = 5.6 min). Increasing the GABA concentration to 20 μM did not change the blocking effect of PTX, but accelerated recovery by 6 times (τrec = 3.3 min). The mechanism of the shortening of the PTX aftereffect is presumably the expansion of the GABAAR pore in the presence of PAMs and a high concentration of the agonist and, as a consequence, the escape of PTX from the "trap". The work describes new pharmacological properties of Allo and Zolp.
Collapse
Affiliation(s)
- Julia V Bukanova
- Brain Research Institute, Research Center of Neurology, Moscow, Russia
| | - Elena I Solntseva
- Brain Research Institute, Research Center of Neurology, Moscow, Russia.
| | | |
Collapse
|
14
|
Niepoth N, Merritt JR, Uminski M, Lei E, Esquibies VS, Bando IB, Hernandez K, Gebhardt C, Wacker SA, Lutzu S, Poudel A, Soma KK, Rudolph S, Bendesky A. Evolution of a novel adrenal cell type that promotes parental care. Nature 2024; 629:1082-1090. [PMID: 38750354 PMCID: PMC11329292 DOI: 10.1038/s41586-024-07423-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 04/15/2024] [Indexed: 05/25/2024]
Abstract
Cell types with specialized functions fundamentally regulate animal behaviour, and yet the genetic mechanisms that underlie the emergence of novel cell types and their consequences for behaviour are not well understood1. Here we show that the monogamous oldfield mouse (Peromyscus polionotus) has recently evolved a novel cell type in the adrenal gland that expresses the enzyme AKR1C18, which converts progesterone into 20α-hydroxyprogesterone. We then demonstrate that 20α-hydroxyprogesterone is more abundant in oldfield mice, where it induces monogamous-typical parental behaviours, than in the closely related promiscuous deer mice (Peromyscus maniculatus). Using quantitative trait locus mapping in a cross between these species, we ultimately find interspecific genetic variation that drives expression of the nuclear protein GADD45A and the glycoprotein tenascin N, which contribute to the emergence and function of this cell type in oldfield mice. Our results provide an example by which the recent evolution of a new cell type in a gland outside the brain contributes to the evolution of social behaviour.
Collapse
Affiliation(s)
- Natalie Niepoth
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Jennifer R Merritt
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Michelle Uminski
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Emily Lei
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Victoria S Esquibies
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Ina B Bando
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Kimberly Hernandez
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Christoph Gebhardt
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Sarah A Wacker
- Department of Chemistry and Biochemistry, Manhattan College, New York, NY, USA
| | - Stefano Lutzu
- Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, USA
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, New York, NY, USA
| | - Asmita Poudel
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kiran K Soma
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephanie Rudolph
- Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, USA
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, New York, NY, USA
| | - Andres Bendesky
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA.
| |
Collapse
|
15
|
Tateiwa H, Evers AS. Neurosteroids and their potential as a safer class of general anesthetics. J Anesth 2024; 38:261-274. [PMID: 38252143 PMCID: PMC10954990 DOI: 10.1007/s00540-023-03291-4] [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: 10/31/2023] [Accepted: 11/25/2023] [Indexed: 01/23/2024]
Abstract
Neurosteroids (NS) are a class of steroids that are synthesized within the central nervous system (CNS). Various NS can either enhance or inhibit CNS excitability and they play important biological roles in brain development, brain function and as mediators of mood. One class of NS, 3α-hydroxy-pregnane steroids such as allopregnanolone (AlloP) or pregnanolone (Preg), inhibits neuronal excitability; these endogenous NS and their analogues have been therapeutically applied as anti-depressants, anti-epileptics and general anesthetics. While NS have many favorable properties as anesthetics (e.g. rapid onset, rapid recovery, minimal cardiorespiratory depression, neuroprotection), they are not currently in clinical use, largely due to problems with formulation. Recent advances in understanding NS mechanisms of action and improved formulations have rekindled interest in development of NS as sedatives and anesthetics. In this review, the synthesis of NS, and their mechanism of action will be reviewed with specific emphasis on their binding sites and actions on γ-aminobutyric acid type A (GABAA) receptors. The potential advantages of NS analogues as sedative and anesthetic agents will be discussed.
Collapse
Affiliation(s)
- Hiroki Tateiwa
- Department of Anesthesiology and Intensive Care Medicine, Kochi Medical School, Kochi, Japan
| | - Alex S Evers
- Department of Anesthesiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA.
| |
Collapse
|
16
|
Hernandez CC, Hu N, Shen W, Macdonald RL. Epileptic Encephalopathy GABRB Structural Variants Share Common Gating and Trafficking Defects. Biomolecules 2023; 13:1790. [PMID: 38136660 PMCID: PMC10741827 DOI: 10.3390/biom13121790] [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: 11/20/2023] [Revised: 12/08/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Variants in the GABRB gene, which encodes the β subunit of the GABAA receptor, have been implicated in various epileptic encephalopathies and related neurodevelopmental disorders such as Dravet syndrome and Angelman syndrome. These conditions are often associated with early-onset seizures, developmental regression, and cognitive impairments. The severity and specific features of these encephalopathies can differ based on the nature of the genetic variant and its impact on GABAA receptor function. These variants can lead to dysfunction in GABAA receptor-mediated inhibition, resulting in an imbalance between neuronal excitation and inhibition that contributes to the development of seizures. Here, 13 de novo EE-associated GABRB variants, occurring as missense mutations, were analyzed to determine their impact on protein stability and flexibility, channel function, and receptor biogenesis. Our results showed that all mutations studied significantly impact the protein structure, altering protein stability, flexibility, and function to varying degrees. Variants mapped to the GABA-binding domain, coupling zone, and pore domain significantly impact the protein structure, modifying the β+/α- interface of the receptor and altering channel activation and receptor trafficking. Our study proposes that the extent of loss or gain of GABAA receptor function can be elucidated by identifying the specific structural domain impacted by mutation and assessing the variability in receptor structural dynamics. This paves the way for future studies to explore and uncover links between the incidence of a variant in the receptor topology and the severity of the related disease.
Collapse
Affiliation(s)
- Ciria C. Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ningning Hu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (N.H.); (W.S.); (R.L.M.)
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (N.H.); (W.S.); (R.L.M.)
| | - Robert L. Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; (N.H.); (W.S.); (R.L.M.)
| |
Collapse
|