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O'Connor EC, Kambara K, Bertrand D. Advancements in the use of xenopus oocytes for modelling neurological disease for novel drug discovery. Expert Opin Drug Discov 2024; 19:173-187. [PMID: 37850233 DOI: 10.1080/17460441.2023.2270902] [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: 05/31/2023] [Accepted: 10/11/2023] [Indexed: 10/19/2023]
Abstract
INTRODUCTION Introduced about 50 years ago, the model of Xenopus oocytes for the expression of recombinant proteins has gained a broad spectrum of applications. The authors herein review the benefits brought from using this model system, with a focus on modeling neurological disease mechanisms and application to drug discovery. AREAS COVERED Using multiple examples spanning from ligand gated ion channels to transporters, this review presents, in the light of the latest publications, the benefits offered from using Xenopus oocytes. Studies range from the characterization of gene mutations to the discovery of novel treatments for disorders of the central nervous system (CNS). EXPERT OPINION Development of new drugs targeting CNS disorders has been marked by failures in the translation from preclinical to clinical studies. As progress in genetics and molecular biology highlights large functional differences arising from a single to a few amino acid exchanges, the need for drug screening and functional testing against human proteins is increasing. The use of Xenopus oocytes to enable precise modeling and characterization of clinically relevant genetic variants constitutes a powerful model system that can be used to inform various aspects of CNS drug discovery and development.
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Affiliation(s)
- Eoin C O'Connor
- Roche Pharma Research and Early Development, Neuroscience & Rare Diseases, Roche Innovation Center Basel, Basel, Switzerland
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Scaduto P, Lauterborn JC, Cox CD, Fracassi A, Zeppillo T, Gutierrez BA, Keene CD, Crane PK, Mukherjee S, Russell WK, Taglialatela G, Limon A. Functional excitatory to inhibitory synaptic imbalance and loss of cognitive performance in people with Alzheimer's disease neuropathologic change. Acta Neuropathol 2023; 145:303-324. [PMID: 36538112 PMCID: PMC9925531 DOI: 10.1007/s00401-022-02526-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 11/12/2022] [Accepted: 11/27/2022] [Indexed: 12/24/2022]
Abstract
Individuals at distinct stages of Alzheimer's disease (AD) show abnormal electroencephalographic activity, which has been linked to network hyperexcitability and cognitive decline. However, whether pro-excitatory changes at the synaptic level are observed in brain areas affected early in AD, and if they are emergent in MCI, is not clearly known. Equally important, it is not known whether global synaptic E/I imbalances correlate with the severity of cognitive impairment in the continuum of AD. Measuring the amplitude of ion currents of human excitatory and inhibitory synaptic receptors microtransplanted from the hippocampus and temporal cortex of cognitively normal, mildly cognitively impaired and AD individuals into surrogate cells, we found regional differences in pro-excitatory shifts of the excitatory to inhibitory (E/I) current ratio that correlates positively with toxic proteins and degree of pathology, and impinges negatively on cognitive performance scores. Using these data with electrophysiologically anchored analysis of the synapto-proteome in the same individuals, we identified a group of proteins sustaining synaptic function and those related to synaptic toxicity. We also found an uncoupling between the function and expression of proteins for GABAergic signaling in the temporal cortex underlying larger E/I and worse cognitive performance. Further analysis of transcriptomic and in situ hybridization datasets from an independent cohort across the continuum of AD confirm regional differences in pro-excitatory shifts of the E/I balance that correlate negatively with the most recent calibrated composite scores for memory, executive function, language and visuospatial abilities, as well as overall cognitive performance. These findings indicate that early shifts of E/I balance may contribute to loss of cognitive capabilities in the continuum of AD clinical syndrome.
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Affiliation(s)
- Pietro Scaduto
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Julie C Lauterborn
- Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA, USA
| | - Conor D Cox
- Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA, USA
| | - Anna Fracassi
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Tommaso Zeppillo
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Berenice A Gutierrez
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - C Dirk Keene
- Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA, USA
| | - Paul K Crane
- Department of Medicine, University of Washington, Seattle, WA, USA
| | | | - William K Russell
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, USA
| | - Giulio Taglialatela
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Agenor Limon
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston, TX, USA.
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Zeppillo T, Schulmann A, Macciardi F, Hjelm BE, Föcking M, Sequeira PA, Guella I, Cotter D, Bunney WE, Limon A, Vawter MP. Functional impairment of cortical AMPA receptors in schizophrenia. Schizophr Res 2022; 249:25-37. [PMID: 32513544 PMCID: PMC7718399 DOI: 10.1016/j.schres.2020.03.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/14/2022]
Abstract
Clinical and preclinical studies suggest that some of the behavioral alterations observed in schizophrenia (SZ) may be mechanistically linked to synaptic dysfunction of glutamatergic signaling. Recent genetic and proteomic studies suggest alterations of cortical glutamate receptors of the AMPA-type (AMPARs), which are the predominant ligand-gated ionic channels of fast transmission at excitatory synapses. The impact of gene and protein alterations on the electrophysiological activity of AMPARs is not known in SZ. In this proof of principle work, using human postmortem brain synaptic membranes isolated from the dorsolateral prefrontal cortex (DLPFC), we combined electrophysiological analysis from microtransplanted synaptic membranes (MSM) with transcriptomic (RNA-Seq) and label-free proteomics data in 10 control and 10 subjects diagnosed with SZ. We observed in SZ a reduction in the amplitude of AMPARs currents elicited by kainate, an agonist of AMPARs that blocks the desensitization of the receptor. This reduction was not associated with protein abundance but with a reduction in kainate's potency to activate AMPARs. Electrophysiologically-anchored dataset analysis (EDA) was used to identify synaptosomal proteins that linearly correlate with the amplitude of the AMPARs responses, gene ontology functional annotations were then used to determine protein-protein interactions. Protein modules associated with positive AMPARs current increases were downregulated in SZ, while protein modules that were upregulated in SZ were associated with decreased AMPARs currents. Our results indicate that transcriptomic and proteomic alterations, frequently observed in the DLPFC in SZ, converge at the synaptic level producing a functional electrophysiological impairment of AMPARs.
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Affiliation(s)
- Tommaso Zeppillo
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, School of Medicine, University of Texas Medical Branch at Galveston, USA; Department of Life Sciences, University of Trieste, B.R.A.I.N., Centre for Neuroscience, Trieste, Italy
| | - Anton Schulmann
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, USA; Current address: National Institute of Mental Health, Human Genetics Branch, Bethesda, MD, USA
| | - Fabio Macciardi
- Department of Psychiatry & Human Behavior, University of California Irvine, CA 92697, USA
| | - Brooke E Hjelm
- Department of Translational Genomics, Keck School of Medicine of USC, University of Southern California (USC), Los Angeles, CA, USA
| | | | - P Adolfo Sequeira
- Department of Psychiatry & Human Behavior, University of California Irvine, CA 92697, USA
| | - Ilaria Guella
- Department of Psychiatry & Human Behavior, University of California Irvine, CA 92697, USA
| | - David Cotter
- Royal College of Surgeons in Ireland, Dublin, Ireland
| | - William E Bunney
- Department of Psychiatry & Human Behavior, University of California Irvine, CA 92697, USA
| | - Agenor Limon
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, School of Medicine, University of Texas Medical Branch at Galveston, USA.
| | - Marquis P Vawter
- Department of Psychiatry & Human Behavior, University of California Irvine, CA 92697, USA.
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Miller B, Moreno N, Gutierrez BA, Limon A. Microtransplantation of Postmortem Native Synaptic mGluRs Receptors into Xenopus Oocytes for Their Functional Analysis. MEMBRANES 2022; 12:931. [PMID: 36295690 PMCID: PMC9609105 DOI: 10.3390/membranes12100931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 09/17/2022] [Accepted: 09/20/2022] [Indexed: 05/13/2023]
Abstract
Metabotropic glutamate receptors (mGluRs) are membrane receptors that play a central role in the modulation of synaptic transmission and neuronal excitability and whose dysregulation is implicated in diverse neurological disorders. Most current understanding about the electrophysiological properties of such receptors has been determined using recombinant proteins. However, recombinant receptors do not necessarily recapitulate the properties of native receptors due to the lack of obligated accessory proteins, some of which are differentially expressed as function of developmental stage and brain region. To overcome this limitation, we sought to microtransplant entire synaptosome membranes from frozen rat cortex into Xenopus oocytes, and directly analyze the responses elicited by native mGluRs. We recorded ion currents elicited by 1 mM glutamate using two electrodes voltage clamp. Glutamate produced a fast ionotropic response (6 ± 0.3 nA) in all microtransplanted oocytes (n = 218 oocytes) and a delayed oscillatory response (52 ± 7 nA) in 73% of them. The participation of Group 1 mGluRs was confirmed by the presence of metabotropic oscillations during the administration of (±)-1-Aminocyclopentane-trans-1,3-dicarboxylic acid (ACPD; Group 1 mGluR agonist), and the absence of oscillations during co-administration of N-(1-adamantyl)quinoxaline-2-carboxamide (NPS 2390; Group 1 mGluR antagonist). Since both mGluR1 and mGluR5 belong to Group 1 mGluRs, further investigation revealed that mGluR1 antagonism with LY 456236 has little effect on metabotropic oscillations, while mGluR5 antagonism with 100 µM AZD 9272 has significant reduction of metabotropic currents elicited by ACPD and glutamate. We confirmed the expression of mGluR1 and mGluR5 in native synaptosomes by immunoblots, both of which are enhanced when compared to their counterpart proteins in rat cortex tissue lysates. Finally, these results demonstrate the merit of using microtransplantation of native synaptosomes for the study of mGluRs and the contribution of mGluR5 to the metabotropic glutamate signaling, providing a better tool for the understanding of the role of these receptors in neurological disorders.
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Affiliation(s)
| | | | | | - Agenor Limon
- Mitchell Center for Neurodegenerative Diseases, Department of Neurology, The University of Texas Medical Branch, Galveston, TX 77555, USA
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Bhatt M, Di Iacovo A, Romanazzi T, Roseti C, Cinquetti R, Bossi E. The "www" of Xenopus laevis Oocytes: The Why, When, What of Xenopus laevis Oocytes in Membrane Transporters Research. MEMBRANES 2022; 12:membranes12100927. [PMID: 36295686 PMCID: PMC9610376 DOI: 10.3390/membranes12100927] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 05/16/2023]
Abstract
After 50 years, the heterologous expression of proteins in Xenopus laevis oocytes is still essential in many research fields. New approaches and revised protocols, but also classical methods, such as the two-electrode voltage clamp, are applied in studying membrane transporters. New and old methods for investigating the activity and the expression of Solute Carriers (SLC) are reviewed, and the kinds of experiment that are still useful to perform with this kind of cell are reported. Xenopus laevis oocytes at the full-grown stage have a highly efficient biosynthetic apparatus that correctly targets functional proteins at the defined compartment. This small protein factory can produce, fold, and localize almost any kind of wild-type or recombinant protein; some tricks are required to obtain high expression and to verify the functionality. The methodologies examined here are mainly related to research in the field of membrane transporters. This work is certainly not exhaustive; it has been carried out to be helpful to researchers who want to quickly find suggestions and detailed indications when investigating the functionality and expression of the different members of the solute carrier families.
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Affiliation(s)
- Manan Bhatt
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Experimental and Translational Medicine, University of Insubria, Via Ottorino Rossi 9, 21100 Varese, Italy
| | - Angela Di Iacovo
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Experimental and Translational Medicine, University of Insubria, Via Ottorino Rossi 9, 21100 Varese, Italy
| | - Tiziana Romanazzi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Experimental and Translational Medicine, University of Insubria, Via Ottorino Rossi 9, 21100 Varese, Italy
| | - Cristina Roseti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Centre for Neuroscience—Via Manara 7, University of Insubria, 21052 Busto Arsizio, Italy
| | - Raffaella Cinquetti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
| | - Elena Bossi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Centre for Neuroscience—Via Manara 7, University of Insubria, 21052 Busto Arsizio, Italy
- Correspondence:
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Neff R, Kambara K, Bertrand D. Ligand gated receptor interactions: A key to the power of neuronal networks. Biochem Pharmacol 2021; 190:114653. [PMID: 34129858 DOI: 10.1016/j.bcp.2021.114653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 10/21/2022]
Abstract
The discovery of the chemical synapse was a seminal finding in Neurobiology but the large body of microscopic interactions involved in synaptic transmission could hardly have been foreseen at the time of these first discoveries. Characterization of the molecular players at work at synapses and the increased granularity at which we can now analyze electrical and chemical signal processing that occur in even the simplest neuronal system are shining a new light on receptor interactions. The aim of this review is to discuss the complexity of some representative interactions between excitatory and inhibitory ligand-gated ion channels and/or G protein coupled receptors, as well as other key machinery that can impact neurotransmission and to explain how such mechanisms can be an important determinant of nervous system function.
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Affiliation(s)
- R Neff
- Janssen R&D, LLC, 3210 Merryfield Row, San Diego, CA 92121, USA
| | - K Kambara
- HiQScreen Sàrl, 6 rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - D Bertrand
- HiQScreen Sàrl, 6 rte de Compois, 1222 Vésenaz, Geneva, Switzerland.
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Lauterborn JC, Scaduto P, Cox CD, Schulmann A, Lynch G, Gall CM, Keene CD, Limon A. Increased excitatory to inhibitory synaptic ratio in parietal cortex samples from individuals with Alzheimer's disease. Nat Commun 2021; 12:2603. [PMID: 33972518 PMCID: PMC8110554 DOI: 10.1038/s41467-021-22742-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/24/2021] [Indexed: 02/08/2023] Open
Abstract
Synaptic disturbances in excitatory to inhibitory (E/I) balance in forebrain circuits are thought to contribute to the progression of Alzheimer's disease (AD) and dementia, although direct evidence for such imbalance in humans is lacking. We assessed anatomical and electrophysiological synaptic E/I ratios in post-mortem parietal cortex samples from middle-aged individuals with AD (early-onset) or Down syndrome (DS) by fluorescence deconvolution tomography and microtransplantation of synaptic membranes. Both approaches revealed significantly elevated E/I ratios for AD, but not DS, versus controls. Gene expression studies in an independent AD cohort also demonstrated elevated E/I ratios in individuals with AD as compared to controls. These findings provide evidence of a marked pro-excitatory perturbation of synaptic E/I balance in AD parietal cortex, a region within the default mode network that is overly active in the disorder, and support the hypothesis that E/I imbalances disrupt cognition-related shifts in cortical activity which contribute to the intellectual decline in AD.
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Affiliation(s)
- Julie C Lauterborn
- Department of Anatomy and Neurobiology, University of California at Irvine, Irvine, CA, USA.
| | - Pietro Scaduto
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases. School of Medicine, University of Texas Medical Branch at Galveston, Galveston, USA
| | - Conor D Cox
- Department of Anatomy and Neurobiology, University of California at Irvine, Irvine, CA, USA
| | - Anton Schulmann
- National Institute of Mental Health, Human Genetics Branch, Bethesda, MD, USA
| | - Gary Lynch
- Department of Anatomy and Neurobiology, University of California at Irvine, Irvine, CA, USA
- Department of Psychiatry & Human Behavior, University of California at Irvine, Irvine, CA, 92697, USA
| | - Christine M Gall
- Department of Anatomy and Neurobiology, University of California at Irvine, Irvine, CA, USA
| | - C Dirk Keene
- Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA, USA
| | - Agenor Limon
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases. School of Medicine, University of Texas Medical Branch at Galveston, Galveston, USA.
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Witkin JM, Ping X, Cerne R, Mouser C, Jin X, Hobbs J, Tiruveedhula VVNPB, Li G, Jahan R, Rashid F, Kumar Golani L, Cook JM, Smith JL. The value of human epileptic tissue in the characterization and development of novel antiepileptic drugs: The example of CERC-611 and KRM-II-81. Brain Res 2019; 1722:146356. [PMID: 31369732 DOI: 10.1016/j.brainres.2019.146356] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/17/2019] [Accepted: 07/29/2019] [Indexed: 12/25/2022]
Abstract
The need for improved antiepileptics is clearly mandated despite the existence of multiple existing medicines from different chemical and mechanistic classes. Standard of care agents do not fully control epilepsies and have a variety of side-effect and safety issues. Patients typically take multiple antiepileptic drugs and yet many continue to have seizures. Antiepileptic-unresponsive seizures are life-disrupting and life-threatening. One approach to seizure control is surgical resection of affected brain tissue and associated neural circuits. Although non-human brain studies can provide insight into novel antiepileptic mechanisms, human epileptic brain is the bottom-line biological substrate. Human epileptic brain can provide definitive information on the presence or absence of the putative protein targets of interest in the patient population, the potential changes in these proteins in the epileptic state, and the engagement of novel molecules and their functional impact in target tissue. In this review, we discuss data on two novel potential antiepileptic drugs. CERC-611 (LY3130481) is an AMPA receptor antagonist that selectively blocks AMPA receptors associated with the auxiliary protein TARP γ-8 and is in clinical development. KRM-II-81 is a positive allosteric modulator of GABAA receptors selectively associated with protein subunits α2 and α 3. Preclinical data on these compounds argue that patient-based biological data increase the probability that a newly discovered molecule will translate its antiepileptic potential to patients.
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Affiliation(s)
- Jeffrey M Witkin
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
| | - Xingjie Ping
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Rok Cerne
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Claire Mouser
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Jon Hobbs
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | | | - Guanguan Li
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Rajwana Jahan
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Farjana Rashid
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Lalit Kumar Golani
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - James M Cook
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, IN, USA.
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