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Nguyen H, Glaaser IW, Slesinger PA. Direct modulation of G protein-gated inwardly rectifying potassium (GIRK) channels. Front Physiol 2024; 15:1386645. [PMID: 38903913 PMCID: PMC11187414 DOI: 10.3389/fphys.2024.1386645] [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: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 06/22/2024] Open
Abstract
Ion channels play a pivotal role in regulating cellular excitability and signal transduction processes. Among the various ion channels, G-protein-coupled inwardly rectifying potassium (GIRK) channels serve as key mediators of neurotransmission and cellular responses to extracellular signals. GIRK channels are members of the larger family of inwardly-rectifying potassium (Kir) channels. Typically, GIRK channels are activated via the direct binding of G-protein βγ subunits upon the activation of G-protein-coupled receptors (GPCRs). GIRK channel activation requires the presence of the lipid signaling molecule, phosphatidylinositol 4,5-bisphosphate (PIP2). GIRK channels are also modulated by endogenous proteins and other molecules, including RGS proteins, cholesterol, and SNX27 as well as exogenous compounds, such as alcohol. In the last decade or so, several groups have developed novel drugs and small molecules, such as ML297, GAT1508 and GiGA1, that activate GIRK channels in a G-protein independent manner. Here, we aim to provide a comprehensive overview focusing on the direct modulation of GIRK channels by G-proteins, PIP2, cholesterol, and novel modulatory compounds. These studies offer valuable insights into the underlying molecular mechanisms of channel function, and have potential implications for both basic research and therapeutic development.
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Affiliation(s)
| | | | - Paul A. Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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Prytkova I, Liu Y, Fernando M, Gameiro-Ros I, Popova D, Kamarajan C, Xuei X, Chorlian DB, Edenberg HJ, Tischfield JA, Porjesz B, Pang ZP, Hart RP, Goate A, Slesinger PA. Upregulated GIRK2 Counteracts Ethanol-Induced Changes in Excitability and Respiration in Human Neurons. J Neurosci 2024; 44:e0918232024. [PMID: 38350999 PMCID: PMC11026340 DOI: 10.1523/jneurosci.0918-23.2024] [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: 05/10/2023] [Revised: 01/05/2024] [Accepted: 01/11/2024] [Indexed: 02/17/2024] Open
Abstract
Genome-wide association studies (GWAS) of electroencephalographic endophenotypes for alcohol use disorder (AUD) has identified noncoding polymorphisms within the KCNJ6 gene. KCNJ6 encodes GIRK2, a subunit of a G-protein-coupled inwardly rectifying potassium channel that regulates neuronal excitability. We studied the effect of upregulating KCNJ6 using an isogenic approach with human glutamatergic neurons derived from induced pluripotent stem cells (male and female donors). Using multielectrode arrays, population calcium imaging, single-cell patch-clamp electrophysiology, and mitochondrial stress tests, we find that elevated GIRK2 acts in concert with 7-21 d of ethanol exposure to inhibit neuronal activity, to counteract ethanol-induced increases in glutamate response, and to promote an increase intrinsic excitability. Furthermore, elevated GIRK2 prevented ethanol-induced changes in basal and activity-dependent mitochondrial respiration. These data support a role for GIRK2 in mitigating the effects of ethanol and a previously unknown connection to mitochondrial function in human glutamatergic neurons.
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Affiliation(s)
- Iya Prytkova
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Yiyuan Liu
- Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Michael Fernando
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Isabel Gameiro-Ros
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Dina Popova
- Human Genetics Institute, Rutgers University, Piscataway, New Jersey 08854
| | - Chella Kamarajan
- Department of Psychiatry & Behavioral Sciences, SUNY Downstate Health Sciences University, Brooklyn, New York 11203
| | - Xiaoling Xuei
- Departments of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - David B Chorlian
- Department of Psychiatry & Behavioral Sciences, SUNY Downstate Health Sciences University, Brooklyn, New York 11203
| | - Howard J Edenberg
- Departments of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202
- Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Jay A Tischfield
- Human Genetics Institute, Rutgers University, Piscataway, New Jersey 08854
| | - Bernice Porjesz
- Department of Psychiatry & Behavioral Sciences, SUNY Downstate Health Sciences University, Brooklyn, New York 11203
| | - Zhiping P Pang
- Human Genetics Institute, Rutgers University, Piscataway, New Jersey 08854
- Department of Neuroscience and Cell Biology and The Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901
| | - Ronald P Hart
- Human Genetics Institute, Rutgers University, Piscataway, New Jersey 08854
- Department of Cell Biology & Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Alison Goate
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
- Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Paul A Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029
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Popova D, Sun J, Chow HM, Hart RP. A critical review of ethanol effects on neuronal firing: A metabolic perspective. ALCOHOL, CLINICAL & EXPERIMENTAL RESEARCH 2024; 48:450-458. [PMID: 38217065 DOI: 10.1111/acer.15266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/22/2023] [Accepted: 01/02/2024] [Indexed: 01/14/2024]
Abstract
Ethanol metabolism is relatively understudied in neurons, even though changes in neuronal metabolism are known to affect their activity. Recent work demonstrates that ethanol is preferentially metabolized over glucose as a source of carbon and energy, and it reprograms neurons to a state of reduced energy potential and diminished capacity to utilize glucose once ethanol is exhausted. Ethanol intake has been associated with changes in neuronal firing and specific brain activity (EEG) patterns have been linked with risk for alcohol use disorder (AUD). Furthermore, a haplotype of the inwardly rectifying potassium channel subunit, GIRK2, which plays a critical role in regulating excitability of neurons, has been linked with AUD and shown to be directly regulated by ethanol. At the same time, overexpression of GIRK2 prevents ethanol-induced metabolic changes. Based on the available evidence, we conclude that the mechanisms underlying the effects of ethanol on neuronal metabolism are a novel target for developing therapies for AUD.
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Affiliation(s)
- Dina Popova
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, USA
| | - Jacquelyne Sun
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, Hong Kong
| | - Hei-Man Chow
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong, Hong Kong
- Gerald Choa Neuroscience Institute, The Chinese University of Hong Kong, Hong Kong, Hong Kong
| | - Ronald P Hart
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, USA
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Prytkova I, Liu Y, Fernando M, Gameiro-Ros I, Popova D, Kamarajan C, Xuei X, Chorlian DB, Edenberg HJ, Tischfield JA, Porjesz B, Pang ZP, Hart RP, Goate A, Slesinger PA. Upregulated GIRK2 counteracts ethanol-induced changes in excitability & respiration in human neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.22.533236. [PMID: 36993693 PMCID: PMC10055374 DOI: 10.1101/2023.03.22.533236] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Genome-wide association analysis (GWAS) of electroencephalographic endophenotypes for alcohol use disorder (AUD) has identified non-coding polymorphisms within the KCNJ6 gene. KCNJ6 encodes GIRK2, a subunit of a G protein-coupled inwardly-rectifying potassium channel that regulates neuronal excitability. How changes in GIRK2 affect human neuronal excitability and the response to repeated ethanol exposure is poorly understood. Here, we studied the effect of upregulating KCNJ6 using an isogenic approach with human glutamatergic neurons derived from induced pluripotent stem cells (male and female donors). Using multi-electrode-arrays, population calcium imaging, single-cell patch-clamp electrophysiology, and mitochondrial stress tests, we find that elevated GIRK2 acts in concert with 7-21 days of ethanol exposure to inhibit neuronal activity, to counteract ethanol-induced increases in glutamate response, and to promote an increase intrinsic excitability. Furthermore, elevated GIRK2 prevented ethanol-dependent changes in basal and activity-dependent mitochondrial respiration. These data support a role for GIRK2 in mitigating the effects of ethanol and a previously unknown connection to mitochondrial function in human glutamatergic neurons. SIGNIFICANCE STATEMENT Alcohol use disorder (AUD) is a major health problem that has worsened since COVID, affecting over 100 million people worldwide. While it is known that heritability contributes to AUD, specific genes and their role in neuronal function remain poorly understood, especially in humans. In the current manuscript, we focused on the inwardly-rectifying potassium channel GIRK2, which has been identified in an AUD-endophenotype genome-wide association study. We used human excitatory neurons derived from healthy donors to study the impact of GIRK2 expression. Our results reveal that elevated GIRK2 counteracts ethanol-induced increases in glutamate response and intracellular calcium, as well as deficits in activity-dependent mitochondrial respiration. The role of GIRK2 in mitigating ethanol-induced hyper-glutamatergic and mitochondrial offers therapeutic promise for treating AUD.
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Agrawal A, Brislin SJ, Bucholz KK, Dick D, Hart RP, Johnson EC, Meyers J, Salvatore J, Slesinger P, Almasy L, Foroud T, Goate A, Hesselbrock V, Kramer J, Kuperman S, Merikangas AK, Nurnberger JI, Tischfield J, Edenberg HJ, Porjesz B. The Collaborative Study on the Genetics of Alcoholism: Overview. GENES, BRAIN, AND BEHAVIOR 2023; 22:e12864. [PMID: 37736010 PMCID: PMC10550790 DOI: 10.1111/gbb.12864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 07/21/2023] [Accepted: 08/23/2023] [Indexed: 09/23/2023]
Abstract
Alcohol use disorders (AUD) are commonly occurring, heritable and polygenic disorders with etiological origins in the brain and the environment. To outline the causes and consequences of alcohol-related milestones, including AUD, and their related psychiatric comorbidities, the Collaborative Study on the Genetics of Alcoholism (COGA) was launched in 1989 with a gene-brain-behavior framework. COGA is a family based, diverse (~25% self-identified African American, ~52% female) sample, including data on 17,878 individuals, ages 7-97 years, in 2246 families of which a proportion are densely affected for AUD. All participants responded to questionnaires (e.g., personality) and the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) which gathers information on psychiatric diagnoses, conditions and related behaviors (e.g., parental monitoring). In addition, 9871 individuals have brain function data from electroencephalogram (EEG) recordings while 12,009 individuals have been genotyped on genome-wide association study (GWAS) arrays. A series of functional genomics studies examine the specific cellular and molecular mechanisms underlying AUD. This overview provides the framework for the development of COGA as a scientific resource in the past three decades, with individual reviews providing in-depth descriptions of data on and discoveries from behavioral and clinical, brain function, genetic and functional genomics data. The value of COGA also resides in its data sharing policies, its efforts to communicate scientific findings to the broader community via a project website and its potential to nurture early career investigators and to generate independent research that has broadened the impact of gene-brain-behavior research into AUD.
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Affiliation(s)
- Arpana Agrawal
- Department of PsychiatryWashington University School of Medicine in St. LouisSt. LouisMissouriUSA
| | - Sarah J. Brislin
- Department of PsychiatryRutgers Robert Wood Johnson Medical SchoolPiscatawayNew JerseyUSA
| | - Kathleen K. Bucholz
- Department of PsychiatryWashington University School of Medicine in St. LouisSt. LouisMissouriUSA
| | - Danielle Dick
- Department of PsychiatryRutgers Robert Wood Johnson Medical SchoolPiscatawayNew JerseyUSA
| | - Ronald P. Hart
- Department of Cell Biology and NeuroscienceRutgers UniversityPiscatawayNew JerseyUSA
| | - Emma C. Johnson
- Department of PsychiatryWashington University School of Medicine in St. LouisSt. LouisMissouriUSA
| | - Jacquelyn Meyers
- Department of Psychiatry and Behavioral SciencesSUNY Downstate Health Sciences UniversityBrooklynNew YorkUSA
| | - Jessica Salvatore
- Department of PsychiatryRutgers Robert Wood Johnson Medical SchoolPiscatawayNew JerseyUSA
| | - Paul Slesinger
- Department of Neuroscience & Friedman Brain InstituteIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
| | - Laura Almasy
- Department of Biomedical and Health InformaticsChildren's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
- Department of Genetics, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
- Lifespan Brain Institute, Children's Hospital of Philadelphia and Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Tatiana Foroud
- Department of Medical and Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
| | - Alison Goate
- Department of Genetics and Genomic SciencesIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
- Department of NeuroscienceIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
- Department of NeurologyIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
| | - Victor Hesselbrock
- Department of PsychiatryUniversity of Connecticut School of MedicineFarmingtonConnecticutUSA
| | - John Kramer
- Department of PsychiatryUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Samuel Kuperman
- Department of PsychiatryUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Alison K. Merikangas
- Department of Biomedical and Health InformaticsChildren's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
- Department of Genetics, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
- Lifespan Brain Institute, Children's Hospital of Philadelphia and Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | | | - Jay Tischfield
- Department of GeneticsRutgers UniversityPiscatawayNew JerseyUSA
| | - Howard J. Edenberg
- Department of Medical and Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
- Department of Biochemistry and Molecular BiologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Bernice Porjesz
- Department of Psychiatry and Behavioral SciencesSUNY Downstate Health Sciences UniversityBrooklynNew YorkUSA
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Ma F, Akolkar H, Xu J, Liu Y, Popova D, Xie J, Youssef MM, Benosman R, Hart RP, Herrup K. The Amyloid Precursor Protein Modulates the Position and Length of the Axon Initial Segment. J Neurosci 2023; 43:1830-1844. [PMID: 36717226 PMCID: PMC10010458 DOI: 10.1523/jneurosci.0172-22.2023] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
The amyloid precursor protein (APP) is linked to the genetics and pathogenesis of Alzheimer's disease (AD). It is the parent protein of the β-amyloid (Aβ) peptide, the main constituent of the amyloid plaques found in an AD brain. The pathways from APP to Aβ are intensively studied, yet the normal functions of APP itself have generated less interest. We report here that glutamate stimulation of neuronal activity leads to a rapid increase in App gene expression. In mouse and human neurons, elevated APP protein changes the structure of the axon initial segment (AIS) where action potentials are initiated. The AIS is shortened in length and shifts away from the cell body. The GCaMP8f Ca2+ reporter confirms the predicted decrease in neuronal activity. NMDA antagonists or knockdown of App block the glutamate effects. The actions of APP on the AIS are cell-autonomous; exogenous Aβ, either fibrillar or oligomeric, has no effect. In culture, APPSwe (a familial AD mutation) induces larger AIS changes than wild type APP. Ankyrin G and βIV-spectrin, scaffolding proteins of the AIS, both physically associate with APP, more so in AD brains. Finally, in humans with sporadic AD or in the R1.40 AD mouse model, both females and males, neurons have elevated levels of APP protein that invade the AIS. In vivo as in vitro, this increased APP is associated with a significant shortening of the AIS. The findings outline a new role for the APP and encourage a reconsideration of its relationship to AD.SIGNIFICANCE STATEMENT While the amyloid precursor protein (APP) has long been associated with Alzheimer's disease (AD), the normal functions of the full-length Type I membrane protein have been largely unexplored. We report here that the levels of APP protein increase with neuronal activity. In vivo and in vitro, modest amounts of excess APP alter the properties of the axon initial segment. The β-amyloid peptide derived from APP is without effect. Consistent with the observed changes in the axon initial segment which would be expected to decrease action potential firing, we show that APP expression depresses neuronal activity. In mouse AD models and human sporadic AD, APP physically associates with the scaffolding proteins of the axon initial segment, suggesting a relationship with AD dementia.
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Affiliation(s)
- Fulin Ma
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Himanshu Akolkar
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Jianquan Xu
- Departments of Medicine and Bioengineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Yang Liu
- Departments of Medicine and Bioengineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Dina Popova
- Human Genetics Institute, Rutgers University, Piscataway, NJ 08854
| | - Jiaan Xie
- Departments of Medicine and Bioengineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Mark M Youssef
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
| | - Ryad Benosman
- Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Ronald P Hart
- Human Genetics Institute, Rutgers University, Piscataway, NJ 08854
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
| | - Karl Herrup
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Departments of Medicine and Bioengineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
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