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Utsumi Y, Taketoshi M, Miwa M, Tominaga Y, Tominaga T. Assessing seizure liability in vitro with voltage-sensitive dye imaging in mouse hippocampal slices. Front Cell Neurosci 2023; 17:1217368. [PMID: 37680865 PMCID: PMC10481167 DOI: 10.3389/fncel.2023.1217368] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/09/2023] [Indexed: 09/09/2023] Open
Abstract
Non-clinical toxicology is a major cause of drug candidate attrition during development. In particular, drug-induced seizures are the most common finding in central nervous system (CNS) toxicity. Current safety pharmacology tests for assessing CNS functions are often inadequate in detecting seizure-inducing compounds early in drug development, leading to significant delays. This paper presents an in vitro seizure liability assay using voltage-sensitive dye (VSD) imaging techniques in hippocampal brain slices, offering a powerful alternative to traditional electrophysiological methods. Hippocampal slices were isolated from mice, and VSD optical responses evoked by stimulating the Schaffer collateral pathway were recorded and analyzed in the stratum radiatum (SR) and stratum pyramidale (SP). VSDs allow for the comprehensive visualization of neuronal action potentials and postsynaptic potentials on a millisecond timescale. By employing this approach, we investigated the in vitro drug-induced seizure liability of representative pro-convulsant compounds. Picrotoxin (PiTX; 1-100 μM), gabazine (GZ; 0.1-10 μM), and 4-aminopyridine (4AP; 10-100 μM) exhibited seizure-like responses in the hippocampus, but pilocarpine hydrochloride (Pilo; 10-100 μM) did not. Our findings demonstrate the potential of VSD-based assays in identifying seizurogenic compounds during early drug discovery, thereby reducing delays in drug development and providing insights into the mechanisms underlying seizure induction and the associated risks of pro-convulsant compounds.
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Affiliation(s)
- Yuichi Utsumi
- Graduate School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
| | - Makiko Taketoshi
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
| | - Michiko Miwa
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
| | - Yoko Tominaga
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
| | - Takashi Tominaga
- Graduate School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
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2
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Ma M, Brunal AA, Clark KC, Studtmann C, Stebbins K, Higashijima SI, Pan YA. Deficiency in the cell-adhesion molecule dscaml1 impairs hypothalamic CRH neuron development and perturbs normal neuroendocrine stress axis function. Front Cell Dev Biol 2023; 11:1113675. [PMID: 36875755 PMCID: PMC9978177 DOI: 10.3389/fcell.2023.1113675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/30/2023] [Indexed: 02/18/2023] Open
Abstract
The corticotropin-releasing hormone (CRH)-expressing neurons in the hypothalamus are critical regulators of the neuroendocrine stress response pathway, known as the hypothalamic-pituitary-adrenal (HPA) axis. As developmental vulnerabilities of CRH neurons contribute to stress-associated neurological and behavioral dysfunctions, it is critical to identify the mechanisms underlying normal and abnormal CRH neuron development. Using zebrafish, we identified Down syndrome cell adhesion molecule like-1 (dscaml1) as an integral mediator of CRH neuron development and necessary for establishing normal stress axis function. In dscaml1 mutant animals, hypothalamic CRH neurons had higher crhb (the CRH homolog in zebrafish) expression, increased cell number, and reduced cell death compared to wild-type controls. Physiologically, dscaml1 mutant animals had higher baseline stress hormone (cortisol) levels and attenuated responses to acute stressors. Together, these findings identify dscaml1 as an essential factor for stress axis development and suggest that HPA axis dysregulation may contribute to the etiology of human DSCAML1-linked neuropsychiatric disorders.
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Affiliation(s)
- Manxiu Ma
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA, United States
| | - Alyssa A Brunal
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA, United States.,Translational Biology Medicine and Health Graduate Program, Virginia Tech, Blacksburg, VA, United States
| | - Kareem C Clark
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA, United States
| | - Carleigh Studtmann
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA, United States.,Translational Biology Medicine and Health Graduate Program, Virginia Tech, Blacksburg, VA, United States
| | - Katelyn Stebbins
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA, United States.,Translational Biology Medicine and Health Graduate Program, Virginia Tech, Blacksburg, VA, United States.,Virginia Tech Carilion School of Medicine, Roanoke, VA, United States
| | - Shin-Ichi Higashijima
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Y Albert Pan
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA, United States.,Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.,Department of Psychiatry and Behavioral Medicine, Virginia Tech Carilion School of Medicine, Roanoke, VA, United States
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3
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Kuramoto T. Positional cloning of rat mutant genes reveals new functions of these genes. Exp Anim 2023; 72:1-8. [PMID: 36058846 PMCID: PMC9978133 DOI: 10.1538/expanim.22-0089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The laboratory rat (Rattus norvegicus) is a key model organism for biomedical research. Rats can be subjected to strict genetic and environmental controls. The rat's large body size is suitable for both surgical operations and repeated measurements of physiological parameters. These advantages have led to the development of numerous rat models for genetic diseases. Forward genetics is a proven approach for identifying the causative genes of these disease models but requires genome resources including genetic markers and genome sequences. Over the last few decades, rat genome resources have been developed and deposited in bioresource centers, which have enabled us to perform positional cloning in rats. To date, more than 100 disease-related genes have been identified by positional cloning. Since some disease models are more accessible in rats than mice, the identification of causative genes in these models has sometimes led to the discovery of novel functions of genes. As before, various mutant rats are also expected to be discovered and developed as disease models in the future. Thus, the forward genetics continues to be an important approach to find genes involved in disease phenotypes in rats. In this review, I provide an overview the development of rat genome resources and describe examples of positional cloning in rats in which novel gene functions have been identified.
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Affiliation(s)
- Takashi Kuramoto
- Laboratory of Animal Nutrition, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa 243-0034, Japan
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Parcerisas A, Ortega-Gascó A, Pujadas L, Soriano E. The Hidden Side of NCAM Family: NCAM2, a Key Cytoskeleton Organization Molecule Regulating Multiple Neural Functions. Int J Mol Sci 2021; 22:10021. [PMID: 34576185 PMCID: PMC8471948 DOI: 10.3390/ijms221810021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/12/2021] [Accepted: 09/14/2021] [Indexed: 02/07/2023] Open
Abstract
Although it has been over 20 years since Neural Cell Adhesion Molecule 2 (NCAM2) was identified as the second member of the NCAM family with a high expression in the nervous system, the knowledge of NCAM2 is still eclipsed by NCAM1. The first studies with NCAM2 focused on the olfactory bulb, where this protein has a key role in axonal projection and axonal/dendritic compartmentalization. In contrast to NCAM1, NCAM2's functions and partners in the brain during development and adulthood have remained largely unknown until not long ago. Recent studies have revealed the importance of NCAM2 in nervous system development. NCAM2 governs neuronal morphogenesis and axodendritic architecture, and controls important neuron-specific processes such as neuronal differentiation, synaptogenesis and memory formation. In the adult brain, NCAM2 is highly expressed in dendritic spines, and it regulates synaptic plasticity and learning processes. NCAM2's functions are related to its ability to adapt to the external inputs of the cell and to modify the cytoskeleton accordingly. Different studies show that NCAM2 interacts with proteins involved in cytoskeleton stability and proteins that regulate calcium influx, which could also modify the cytoskeleton. In this review, we examine the evidence that points to NCAM2 as a crucial cytoskeleton regulation protein during brain development and adulthood. This key function of NCAM2 may offer promising new therapeutic approaches for the treatment of neurodevelopmental diseases and neurodegenerative disorders.
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Affiliation(s)
- Antoni Parcerisas
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, University of Barcelona, 08028 Barcelona, Spain; (A.O.-G.); (L.P.)
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Basic Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Spain
| | - Alba Ortega-Gascó
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, University of Barcelona, 08028 Barcelona, Spain; (A.O.-G.); (L.P.)
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Lluís Pujadas
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, University of Barcelona, 08028 Barcelona, Spain; (A.O.-G.); (L.P.)
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Eduardo Soriano
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, University of Barcelona, 08028 Barcelona, Spain; (A.O.-G.); (L.P.)
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
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Szpirer C. Rat Models of Human Diseases and Related Phenotypes: A Novel Inventory of Causative Genes. Mamm Genome 2021; 33:88-90. [PMID: 34184128 DOI: 10.1007/s00335-021-09876-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 05/11/2021] [Indexed: 10/21/2022]
Abstract
The laboratory rat (Rattus norvegicus) has been used for a long time as the model of choice in several biomedical disciplines. In 2020, I made an inventory of rat genes that had been identified as underlying diseases or playing a key role in critical biological processes that are altered in diseases. Over 350 genes could be found, a significant number of which have similar effects in rat and humans (Szpirer in J Biomed Sci 27:84-155, 2020). However, a few rat disease genes were unintentionally overlooked; in addition, since this review was published, numerous rat genes were inactivated by targeted mutations, revealing their potential role in diseases. It thus seems appropriate to update these data, which is the aim of this paper.
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Affiliation(s)
- Claude Szpirer
- Université Libre de Bruxelles, B-6041, Gosselies, Belgium. .,, Avenue Jassogne, 27, B-1410, Waterloo, Belgium.
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Eslami Rasekh M, Hernández Y, Drinan SD, Fuxman Bass J, Benson G. Genome-wide characterization of human minisatellite VNTRs: population-specific alleles and gene expression differences. Nucleic Acids Res 2021; 49:4308-4324. [PMID: 33849068 PMCID: PMC8096271 DOI: 10.1093/nar/gkab224] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/06/2021] [Accepted: 03/18/2021] [Indexed: 11/12/2022] Open
Abstract
Variable Number Tandem Repeats (VNTRs) are tandem repeat (TR) loci that vary in copy number across a population. Using our program, VNTRseek, we analyzed human whole genome sequencing datasets from 2770 individuals in order to detect minisatellite VNTRs, i.e., those with pattern sizes ≥7 bp. We detected 35 638 VNTR loci and classified 5676 as commonly polymorphic (i.e. with non-reference alleles occurring in >5% of the population). Commonly polymorphic VNTR loci were found to be enriched in genomic regions with regulatory function, i.e. transcription start sites and enhancers. Investigation of the commonly polymorphic VNTRs in the context of population ancestry revealed that 1096 loci contained population-specific alleles and that those could be used to classify individuals into super-populations with near-perfect accuracy. Search for quantitative trait loci (eQTLs), among the VNTRs proximal to genes, indicated that in 187 genes expression differences correlated with VNTR genotype. We validated our predictions in several ways, including experimentally, through the identification of predicted alleles in long reads, and by comparisons showing consistency between sequencing platforms. This study is the most comprehensive analysis of minisatellite VNTRs in the human population to date.
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Affiliation(s)
| | - Yözen Hernández
- Graduate Program in Bioinformatics, Boston University, Boston, MA 02215, USA
| | | | - Juan I Fuxman Bass
- Graduate Program in Bioinformatics, Boston University, Boston, MA 02215, USA
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Gary Benson
- Graduate Program in Bioinformatics, Boston University, Boston, MA 02215, USA
- Department of Biology, Boston University, Boston, MA 02215, USA
- Department of Computer Science, Boston University, Boston, MA 02215, USA
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Ogata S, Hashizume K, Hayase Y, Kanno Y, Hori K, Balan S, Yoshikawa T, Takahashi H, Taya S, Hoshino M. Potential involvement of DSCAML1 mutations in neurodevelopmental disorders. Genes Cells 2021; 26:136-151. [PMID: 33501714 DOI: 10.1111/gtc.12831] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 12/24/2022]
Abstract
The molecular mechanisms underlying neurodevelopmental disorders (NDDs) remain unclear. We previously identified Down syndrome cell adhesion molecule like 1 (Dscaml1) as a responsible gene for Ihara epileptic rat (IER), a rat model for human NDDs with epilepsy. However, the relationship between NDDs and DSCAML1 in humans is still elusive. In this study, we screened databases of autism spectrum disorders (ASD), intellectual disability (ID)/developmental disorders (DD) and schizophrenia for genomic mutations in human DSCAML1. We then performed in silico analyses to estimate the potential damage to the mutated DSCAML1 proteins and chose three representative mutations (DSCAML1C729R , DSCAML1R1685* and DSCAML1K2108Nfs*37 ), which lacked a cysteine residue in the seventh Ig domain, the intracellular region and the C-terminal PDZ-binding motif, respectively. In overexpression experiments in a cell line, DSCAML1C729R lost its mature N-glycosylation, whereas DSCAML1K2108Nfs*37 was abnormally degraded via proteasome-dependent protein degradation. Furthermore, in primary hippocampal neurons, the ability of the wild-type DSCAML1 to regulate the number of synapses was lost with all mutant proteins. These results provide insight into understanding the roles of the domains in the DSCAML1 protein and further suggest that these mutations cause functional changes, albeit through different mechanisms, that likely affect the pathophysiology of NDDs.
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Affiliation(s)
- Shigehiro Ogata
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
- Department of Psychiatry and Behavioral Sciences, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
| | - Koichi Hashizume
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Yoneko Hayase
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Yukie Kanno
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Kei Hori
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Shabeesh Balan
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Hidehiko Takahashi
- Department of Psychiatry and Behavioral Sciences, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
| | - Shinichiro Taya
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Mikio Hoshino
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, NCNP, Tokyo, Japan
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