1
|
Garcia-Rosa S, de Freitas Brenha B, Felipe da Rocha V, Goulart E, Araujo BHS. Personalized Medicine Using Cutting Edge Technologies for Genetic Epilepsies. Curr Neuropharmacol 2021; 19:813-831. [PMID: 32933463 PMCID: PMC8686309 DOI: 10.2174/1570159x18666200915151909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/08/2020] [Accepted: 08/28/2020] [Indexed: 11/22/2022] Open
Abstract
Epilepsy is the most common chronic neurologic disorder in the world, affecting 1-2% of the population. Besides, 30% of epilepsy patients are drug-resistant. Genomic mutations seem to play a key role in its etiology and knowledge of strong effect mutations in protein structures might improve prediction and the development of efficacious drugs to treat epilepsy. Several genetic association studies have been undertaken to examine the effect of a range of candidate genes for resistance. Although, few studies have explored the effect of the mutations into protein structure and biophysics in the epilepsy field. Much work remains to be done, but the plans made for exciting developments will hold therapeutic potential for patients with drug-resistance. In summary, we provide a critical review of the perspectives for the development of individualized medicine for epilepsy based on genetic polymorphisms/mutations in light of core elements such as transcriptomics, structural biology, disease model, pharmacogenomics and pharmacokinetics in a manner to improve the success of trial designs of antiepileptic drugs.
Collapse
Affiliation(s)
- Sheila Garcia-Rosa
- Brazilian Biosciences National Laboratory (LNBio), Center for Research in Energy and Material (CNPEM), Campinas, SP, Brazil
| | - Bianca de Freitas Brenha
- Laboratory of Embryonic Genetic Regulation, Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil
| | - Vinicius Felipe da Rocha
- Brazilian Biosciences National Laboratory (LNBio), Center for Research in Energy and Material (CNPEM), Campinas, SP, Brazil
| | - Ernesto Goulart
- Human Genome and Stem-Cell Research Center (HUG-CEL), Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, SP, Brazil
| | - Bruno Henrique Silva Araujo
- Brazilian Biosciences National Laboratory (LNBio), Center for Research in Energy and Material (CNPEM), Campinas, SP, Brazil
| |
Collapse
|
2
|
Exploration of Ion Channels in the Clitoris: a Review. CURRENT SEXUAL HEALTH REPORTS 2019. [DOI: 10.1007/s11930-019-00206-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
3
|
Xu X, Yang X, Wu Q, Liu A, Yang X, Ye AY, Huang AY, Li J, Wang M, Yu Z, Wang S, Zhang Z, Wu X, Wei L, Zhang Y. Amplicon Resequencing Identified Parental Mosaicism for Approximately 10% of "de novo" SCN1A Mutations in Children with Dravet Syndrome. Hum Mutat 2015; 36:861-72. [PMID: 26096185 PMCID: PMC5034833 DOI: 10.1002/humu.22819] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 05/28/2015] [Indexed: 12/13/2022]
Abstract
The majority of children with Dravet syndrome (DS) are caused by de novo SCN1A mutations. To investigate the origin of the mutations, we developed and applied a new method that combined deep amplicon resequencing with a Bayesian model to detect and quantify allelic fractions with improved sensitivity. Of 174 SCN1A mutations in DS probands which were considered "de novo" by Sanger sequencing, we identified 15 cases (8.6%) of parental mosaicism. We identified another five cases of parental mosaicism that were also detectable by Sanger sequencing. Fraction of mutant alleles in the 20 cases of parental mosaicism ranged from 1.1% to 32.6%. Thirteen (65% of 20) mutations originated paternally and seven (35% of 20) maternally. Twelve (60% of 20) mosaic parents did not have any epileptic symptoms. Their mutant allelic fractions were significantly lower than those in mosaic parents with epileptic symptoms (P = 0.016). We identified mosaicism with varied allelic fractions in blood, saliva, urine, hair follicle, oral epithelium, and semen, demonstrating that postzygotic mutations could affect multiple somatic cells as well as germ cells. Our results suggest that more sensitive tools for detecting low-level mosaicism in parents of families with seemingly "de novo" mutations will allow for better informed genetic counseling.
Collapse
Affiliation(s)
- Xiaojing Xu
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Xiaoxu Yang
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
| | - Qixi Wu
- National Institute of Biological SciencesBeijingChina
| | - Aijie Liu
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Xiaoling Yang
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Adam Yongxin Ye
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
- Peking‐Tsinghua Center for Life SciencesBeijingChina
- Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijingChina
| | | | - Jiarui Li
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
| | - Meng Wang
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
| | - Zhe Yu
- National Institute of Biological SciencesBeijingChina
| | - Sheng Wang
- National Institute of Biological SciencesBeijingChina
- College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhichao Zhang
- Andrology CenterPeking University First HospitalBeijingChina
| | - Xiru Wu
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Liping Wei
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
- National Institute of Biological SciencesBeijingChina
| | - Yuehua Zhang
- Department of PediatricsPeking University First HospitalBeijingChina
| |
Collapse
|
4
|
Hatch RJ, Reid CA, Petrou S. Enhanced in vitro CA1 network activity in a sodium channel β1(C121W) subunit model of genetic epilepsy. Epilepsia 2014; 55:601-8. [PMID: 24605816 DOI: 10.1111/epi.12568] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVE A NaV β1(C121W) mouse model of human genetic epilepsy has enhanced neuronal excitability and temperature sensitivity attributed to a decreased threshold for action potential firing in the axon initial segment. To investigate the network consequences of this neuronal dysfunction and to establish a genetic disease state model we developed an in vitro assay to investigate CA1 network properties and antiepileptic drug sensitivity. METHODS CA1 network oscillations were induced by tetanic stimulation and average number of spikes, interspike interval (ISI), duration, and latency were measured in slices from control and NaV β1(C121W) heterozygous mice in the presence and absence of retigabine or carbamazepine. Retigabine was also tested in a thermogenic seizure model. RESULTS Oscillations were reliably induced by tetanic stimulation and were maintained after severing connections between CA3 and CA1, suggesting a local recurrent circuit. Blocking α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), γ-aminobutyric acid receptor A (GABAA ), Ih , and T-type Ca(2+) channels/receptors reduced the number of spikes. Slices from NaV β1(C121W) heterozygous mice displayed several hallmarks of increased network excitability including increases in duration of the oscillation, the number and frequency of spikes and a decrease in their onset latency. The effect of genotype on network excitability was temperature sensitive, as it was seen only at elevated temperatures. Carbamazepine and retigabine were more effective in reducing network excitability in slices from NaV β1(C121W) heterozygous mice. Retigabine appeared to be more effective in suppressing time to thermogenic seizures in NaV β1(C121W) heterozygous mice compared to wild-type (WT) controls. SIGNIFICANCE Hippocampal networks of the NaV β1(C121W) heterozygous mouse model of genetic epilepsy show enhanced excitability consistent with earlier single neuron studies bridging important scales of brain complexity relevant to seizure genesis. Altered pharmacosensitivity further suggests that genetic epilepsy models may be useful in the development of novel antiepileptic drugs that target disease state pathology. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.
Collapse
Affiliation(s)
- Robert J Hatch
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | | | | |
Collapse
|
5
|
Barrera-Bailón B, Oliveira JAC, López DE, Muñoz LJ, Garcia-Cairasco N, Sancho C. Pharmacological and neuroethological studies of three antiepileptic drugs in the Genetic Audiogenic Seizure Hamster (GASH:Sal). Epilepsy Behav 2013; 28:413-25. [PMID: 23872084 DOI: 10.1016/j.yebeh.2013.05.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/21/2013] [Accepted: 05/22/2013] [Indexed: 12/25/2022]
Abstract
Epilepsy modeling is essential for understanding the basic mechanisms of the epileptic process. The Genetic Audiogenic Seizure Hamster (GASH:Sal) exhibits generalized tonic-clonic seizures of genetic origin in response to sound stimulation and is currently being validated as a reliable model of epilepsy. Here, we performed a pharmacological and neuroethological study using well-known and widely used antiepileptic drugs (AEDs), including phenobarbital (PB), valproic acid (VPA), and levetiracetam (LEV). The intraperitoneal administration of PB (5-20mg/kg) and VPA (100-300mg/kg) produced a dose-dependent decrease in GASH:Sal audiogenic seizure severity scores. The administration of LEV (30-100mg/kg) did not produce a clear effect. Phenobarbital showed a short plasmatic life and had a high antiepileptic effect starting at 10mg/kg that was accompanied by ataxia. Valproic acid acted only at high concentrations and was the AED with the most ataxic effects. Levetiracetam at all doses also produced sedation and ataxia side effects. We conclude that the GASH:Sal is a reliable genetic model of epilepsy suitable to evaluate AEDs.
Collapse
Affiliation(s)
- B Barrera-Bailón
- Institute of Neurosciences of Castilla and León/IBSAL, University of Salamanca, Salamanca, Spain
| | | | | | | | | | | |
Collapse
|
6
|
Kaphzan H, Hernandez P, Jung JI, Cowansage KK, Deinhardt K, Chao MV, Abel T, Klann E. Reversal of impaired hippocampal long-term potentiation and contextual fear memory deficits in Angelman syndrome model mice by ErbB inhibitors. Biol Psychiatry 2012; 72:182-90. [PMID: 22381732 PMCID: PMC3368039 DOI: 10.1016/j.biopsych.2012.01.021] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 01/20/2012] [Accepted: 01/20/2012] [Indexed: 12/17/2022]
Abstract
BACKGROUND Angelman syndrome (AS) is a human neuropsychiatric disorder associated with autism, mental retardation, motor abnormalities, and epilepsy. In most cases, AS is caused by the deletion of the maternal copy of UBE3A gene, which encodes the enzyme ubiquitin ligase E3A, also termed E6-AP. A mouse model of AS has been generated and these mice exhibit many of the observed neurological alterations in humans. Because of clinical and neuroanatomical similarities between AS and schizophrenia, we examined AS model mice for alterations in the neuregulin-ErbB4 pathway, which has been implicated in the pathophysiology of schizophrenia. We focused our studies on the hippocampus, one of the major brain loci impaired in AS mice. METHODS We determined the expression of neuregulin 1 and ErbB4 receptors in AS mice and wild-type littermates (ages 10-16 weeks) and studied the effects of ErbB inhibition on long-term potentiation in hippocampal area cornu ammonis 1 and on hippocampus-dependent contextual fear memory. RESULTS We observed enhanced neuregulin-ErbB4 signaling in the hippocampus of AS model mice and found that ErbB inhibitors could reverse deficits in long-term potentiation, a cellular substrate for learning and memory. In addition, we found that an ErbB inhibitor enhanced long-term contextual fear memory in AS model mice. CONCLUSIONS Our findings suggest that neuregulin-ErbB4 signaling is involved in synaptic plasticity and memory impairments in AS model mice, suggesting that ErbB inhibitors have therapeutic potential for the treatment of AS.
Collapse
Affiliation(s)
- Hanoch Kaphzan
- Center for Neural Science, New York University, New York, NY 10003
| | - Pepe Hernandez
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Joo In Jung
- Center for Neural Science, New York University, New York, NY 10003
| | | | - Katrin Deinhardt
- Departments of Cell Biology, Physiology and Neuroscience, New York University School of Medicine, New York, NY 10016,Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Moses V. Chao
- Departments of Cell Biology, Physiology and Neuroscience, New York University School of Medicine, New York, NY 10016,Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Ted Abel
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Eric Klann
- Center for Neural Science, New York University, New York, NY 10003,To whom correspondence should be addressed: Eric Klann, Ph.D., Center for Neural Science, New York University, 4 Washington Place, Room 809, New York, NY 10003, phone: (212) 992-9769, , fax: (212) 995-4011
| |
Collapse
|
7
|
Różycka A, Dorszewska J, Jagodziński PP. Zaburzenia czynności kanałów jonowych w patogenezie padaczek idiopatycznych. Neurol Neurochir Pol 2011; 45:42-56. [PMID: 21384293 DOI: 10.1016/s0028-3843(14)60059-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Abstract
Mutations in a number of genes encoding voltage-gated sodium channels cause a variety of epilepsy syndromes in humans, including genetic (generalized) epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS, severe myoclonic epilepsy of infancy). Most of these mutations are in the SCN1A gene, and all are dominantly inherited. Most of the mutations that cause DS result in loss of function, whereas all of the known mutations that cause GEFS+ are missense, presumably altering channel activity. Family members with the same GEFS+ mutation often display a wide range of seizure types and severities, and at least part of this variability likely results from variation in other genes. Many different biophysical effects of SCN1A-GEFS+ mutations have been observed in heterologous expression systems, consistent with both gain and loss of channel activity. However, results from mouse models suggest that the primary effect of both GEFS+ and DS mutations is to decrease the activity of GABAergic inhibitory neurons. Decreased activity of the inhibitory circuitry is thus likely to be a major factor contributing to seizure generation in patients with GEFS+ and DS, and may be a general consequence of SCN1A mutations.
Collapse
Affiliation(s)
- Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, Georgia 30322, USA.
| | | |
Collapse
|
9
|
Albuquerque EX, Pereira EFR, Alkondon M, Rogers SW. Mammalian nicotinic acetylcholine receptors: from structure to function. Physiol Rev 2009; 89:73-120. [PMID: 19126755 PMCID: PMC2713585 DOI: 10.1152/physrev.00015.2008] [Citation(s) in RCA: 1224] [Impact Index Per Article: 81.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The classical studies of nicotine by Langley at the turn of the 20th century introduced the concept of a "receptive substance," from which the idea of a "receptor" came to light. Subsequent studies aided by the Torpedo electric organ, a rich source of muscle-type nicotinic receptors (nAChRs), and the discovery of alpha-bungarotoxin, a snake toxin that binds pseudo-irreversibly to the muscle nAChR, resulted in the muscle nAChR being the best characterized ligand-gated ion channel hitherto. With the advancement of functional and genetic studies in the late 1980s, the existence of nAChRs in the mammalian brain was confirmed and the realization that the numerous nAChR subtypes contribute to the psychoactive properties of nicotine and other drugs of abuse and to the neuropathology of various diseases, including Alzheimer's, Parkinson's, and schizophrenia, has since emerged. This review provides a comprehensive overview of these findings and the more recent revelations of the impact that the rich diversity in function and expression of this receptor family has on neuronal and nonneuronal cells throughout the body. Despite these numerous developments, our understanding of the contributions of specific neuronal nAChR subtypes to the many facets of physiology throughout the body remains in its infancy.
Collapse
Affiliation(s)
- Edson X Albuquerque
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | | | | |
Collapse
|
10
|
Beck H, Elger CE. Epilepsy research: a window onto function to and dysfunction of the human brain. DIALOGUES IN CLINICAL NEUROSCIENCE 2008. [PMID: 18472480 PMCID: PMC3181865 DOI: 10.31887/dcns.2008.10.1/hbeck] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As one of the most common neurological disorders, epilepsy has devastating behavioral, social, and occupational consequences and is associated with accumulating brain damage and neurological deficits. Epilepsy comprises a large number of syndromes, which vary greatly respect to their etiology and clinical features, but share the characteristic clinical hallmark of epilepsy recurrent spontaneous seizures. Research aimed at understanding the genetic, molecular, and cellular basis of epilepsy has to integrate various research approaches and techniques ranging from clinical expertise, functional analyses of the system and cellular levels, both in human subjects and rodent models of epilepsy, to human and mouse genetics. This knowledge may then be developed into novel treatment options with better control of seizures andlor fewer side effects. In addition, the study of epilepsy has frequently shed light on basic mechanisms underlying the function and dysfunction of the human brain.
Collapse
Affiliation(s)
- Heinz Beck
- Department of Epileptology, University of Bonn Medical Center, Bonn, Germany
| | | |
Collapse
|
11
|
Hoda JC, Gu W, Friedli M, Phillips HA, Bertrand S, Antonarakis SE, Goudie D, Roberts R, Scheffer IE, Marini C, Patel J, Berkovic SF, Mulley JC, Steinlein OK, Bertrand D. Human Nocturnal Frontal Lobe Epilepsy: Pharmocogenomic Profiles of Pathogenic Nicotinic Acetylcholine Receptor β-Subunit Mutations outside the Ion Channel Pore. Mol Pharmacol 2008; 74:379-91. [DOI: 10.1124/mol.107.044545] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
12
|
Li H, Li N, Shen L, Jiang H, Yang Q, Song Y, Guo J, Xia K, Pan Q, Tang B. A novel mutation of KCNQ3 gene in a Chinese family with benign familial neonatal convulsions. Epilepsy Res 2008; 79:1-5. [PMID: 18249525 DOI: 10.1016/j.eplepsyres.2007.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Accepted: 12/05/2007] [Indexed: 01/15/2023]
Abstract
Benign familial neonatal convulsions (BFNC, also named benign familial neonatal seizures, BFNS) is a rare autosomal dominant inherited epilepsy syndrome with clinical and genetic heterogeneity. Two voltage-gated potassium channel subunit genes, KCNQ2 and KCNQ3, have been identified to cause BFNC1 and BFNC2, respectively. To date, only three mutations of KCNQ3, all located within exon 5, have been reported. By limited linkage analysis and mutation analysis of KCNQ3 in a Chinese family with BFNC, we identified a novel missense mutation of KCNQ3, c.988C>T located within exon 6. c.988C>T led to the substitution Cys for Arg in amino acid position 330 (p.R330C) in KCNQ3 potassium channel, which possibly impaired the neuronal M-current and altered neuronal excitability. Seizures of all BFNC patients started from day 2 to 3 after birth and remitted during 1 month, and no recurrence was found. One family member who displayed fever-associated seizures for two times at age 5 years and was diagnosed as febrile seizures, however, did not carry this mutation, which suggests that febrile seizures and BFNC have different pathogenesis. To our knowledge, this is the first report of KCNQ3 mutation in Chinese family with BFNC.
Collapse
Affiliation(s)
- Haiyan Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, PR China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Reduced cortical inhibition in a mouse model of familial childhood absence epilepsy. Proc Natl Acad Sci U S A 2007; 104:17536-41. [PMID: 17947380 DOI: 10.1073/pnas.0708440104] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in the GABA(A) receptor gamma2 subunit are associated with childhood absence epilepsy and febrile seizures. To understand better the molecular basis of absence epilepsy in man, we developed a mouse model harboring a gamma2 subunit point mutation (R43Q) found in a large Australian family. Mice heterozygous for the mutation demonstrated behavioral arrest associated with 6-to 7-Hz spike-and-wave discharges, which are blocked by ethosuximide, a first-line treatment for absence epilepsy in man. Seizures in the mouse showed an abrupt onset at around age 20 days corresponding to the childhood nature of this disease. Reduced cell surface expression of gamma2(R43Q) was seen in heterozygous mice in the absence of any change in alpha1 subunit surface expression, ruling out a dominant-negative effect. GABA(A)-mediated synaptic currents recorded from cortical pyramidal neurons revealed a small but significant reduction that was not seen in the reticular or ventrobasal thalamic nuclei. We hypothesize that a subtle reduction in cortical inhibition underlies childhood absence epilepsy seen in humans harboring the R43Q mutation.
Collapse
|
14
|
Wolfe DM, Pearce DA. Channeling studies in yeast: yeast as a model for channelopathies? Neuromolecular Med 2007; 8:279-306. [PMID: 16775381 DOI: 10.1385/nmm:8:3:279] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 11/30/1999] [Accepted: 01/09/2006] [Indexed: 01/30/2023]
Abstract
Regulation of the concentration of ions within a cell is mediated by their specific transport and sequestration across cellular membranes. This regulation constitutes a major factor in the maintenance of correct cellular homeostasis, with the transport occurring through the action of a large number of different channel proteins localized to the plasma membrane as well as to various organelles. These ion channels vary in specificity from broad (cationic vs anionic) to highly selective (chloride vs sodium). Mutations in many of these channels result in a large number of human diseases, collectively termed channelopathies. Characterization of many of these channels has been undertaken in a variety of both prokaryotic and eukaryotic organisms. Among these organisms is the budding yeast Saccharomyces cerevisiae. Possessing a fully annotated genome, S. cerevisiae would appear to be an ideal organism in which to study this class of proteins associated to diseases. We have compiled and reviewed a list of yeast ion channels, each possessing a human homolog implicated in a channelopathy. Although yeast has been used for the study of other human disease, it has been under utilized for channelopathy research. The utility of using yeast as a model system for studying ion channels associated to human disease is illustrated using yeast lacking the GEF1 gene product that encodes the human homolog to the chloride channel CLC-3.
Collapse
Affiliation(s)
- Devin M Wolfe
- Center for Aging and Developmental Biology, Aab Institute of Biomedical Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | | |
Collapse
|
15
|
Li X, Yang Q, Kuang H, Jiang N, Hu Y. Involvement of Scn1b and Kcna1 ion channels in audiogenic seizures and PTZ-induced epilepsy. Epilepsy Res 2005; 66:155-63. [PMID: 16157473 DOI: 10.1016/j.eplepsyres.2005.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 08/02/2005] [Accepted: 08/08/2005] [Indexed: 11/18/2022]
Abstract
We have undertaken chemical genetic approach using Qingyangshenylycosides (QYS), a natural product compound, to explore the molecular mechanisms underlying different types of epilepsy models. Two animal models were used for these studies, i.e., audiogenic seizure (AGS) and pentylenetetrazol (PTZ)-induced generalized epilepsy in DBA/2J mice. We show that the latency of AGS is prolonged and the severity of seizures (the percentages of the tonus, Tonus_%) is reduced in the QYS-treated animals. These results indicate that QYS has anticonvulsant effect on the AGS model. However, we find that administration of QYS has an opposite effects on PTZ-induced generalized epilepsy. Both the latency of the generalized epilepsy and the latency of death are decreased after QYS treatment in PTZ-induced epilepsy. We examine the molecular basis of the distinct roles of QYS in these two epilepsy models by using gene expression data. Our results show that a voltage-gated sodium channel (Scn1b) and a voltage-gated potassium channel (Kcna1) are differentially expressed in AGS and PTZ-induced epilepsy models as well as in QYS-treated animals. Our results demonstrate that a chemical genetic approach may help to reveal both the molecular mechanisms of different epilepsies and the mechanism of action of the antiepileptic drugs.
Collapse
MESH Headings
- Age Factors
- Analysis of Variance
- Animals
- Anticonvulsants/pharmacology
- Behavior, Animal
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drug Interactions
- Drugs, Chinese Herbal/chemistry
- Drugs, Chinese Herbal/pharmacology
- Epilepsy/chemically induced
- Epilepsy/drug therapy
- Epilepsy/metabolism
- Epilepsy/physiopathology
- Epilepsy, Reflex/drug therapy
- Epilepsy, Reflex/metabolism
- Epilepsy, Reflex/physiopathology
- Gene Expression Regulation/drug effects
- Kv1.1 Potassium Channel/metabolism
- Mice
- Mice, Inbred DBA
- Pentylenetetrazole
- RNA, Messenger/biosynthesis
- Reaction Time/drug effects
- Reaction Time/physiology
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Sodium Channels/metabolism
Collapse
Affiliation(s)
- Xianchun Li
- Key Lab of Brain Functional Genomics, MOE&STCSM, Shanghai Institute of Brain Functional Genomics, East China Normal University, 3663 Zhongshan Road, N. Shanghai 200062, China
| | | | | | | | | |
Collapse
|
16
|
Yagi H, Takamura Y, Yoneda T, Konno D, Akagi Y, Yoshida K, Sato M. Vlgr1 knockout mice show audiogenic seizure susceptibility. J Neurochem 2005; 92:191-202. [PMID: 15606908 DOI: 10.1111/j.1471-4159.2004.02875.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Susceptibility to audiogenic seizures, which are reflex seizures provoked by loud noise, can be induced in rodents by acoustic priming (exposing animals to strong auditory stimuli at an early developmental stage). Some strains of mice and rats are susceptible to audiogenic seizures without priming and these have been used as good experimental models with which to study epilepsies. Here we identified Vlgr1d and Vlgr1e, novel alternatively-spliced variants of Vlgr1b/MGR1, which, upon sequence analysis, were shown to be transcripts from a locus previously characterized as mass1. Vlgr1 (Vlgr1b, Vlgr1d and Vlgr1e) mRNA is expressed predominantly in the neuroepithelium of the developing mouse brain. Our protein-tagged experiment suggested that Vlgr1d and Vlgr1e are secretory molecules, while Vlgr1b is a receptor. Knockout mice lacking exons 2-4 of Vlgr1 were susceptible to audiogenic seizures without priming, although there were no apparent histological abnormalities in their brains. Ninety-five percent of these knockout mice exhibited wild running, a feature typical of the preconvulsive phase of audiogenic seizures triggered by loud noise (11 kHz, 105 dB), and 68% exhibited tonic convulsions at 3 weeks after birth. Our monogenic mice, which have a unique genetic background, serve as a useful tool for further studies on seizures.
Collapse
Affiliation(s)
- Hideshi Yagi
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Japan
| | | | | | | | | | | | | |
Collapse
|
17
|
Nair RR, Thomas SV. Genetic liability to epilepsy in Kerala State, India. Epilepsy Res 2004; 62:163-70. [PMID: 15579304 DOI: 10.1016/j.eplepsyres.2004.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Revised: 08/28/2004] [Accepted: 08/31/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND Familial clustering is common in epilepsies, but pedigree patterns suggest a multi-factorial inheritance. Genetic liability for multi-factorial inheritance is population specific and such data are not available for the population of Kerala or other states in south India. OBJECTIVES In this study, we have attempted to determine the genetic liability to epilepsy based on an adult population of this state. MATERIAL AND METHODS Pedigrees were recorded for probands who reported to the Kerala Registry of Epilepsy and Pregnancy. In order to obtain a genetically matched sample for comparison and estimation of empiric risks, we have used the family history of the spouse except when the spouse was proband's relative. The ILAE criteria were followed for diagnosis and classification of epilepsy. RESULTS Data were collected on 18,419 family members of 505 probands with epilepsy (82 men and 423 women) and 10,231 family members of spouses (control). The frequency of epilepsy in first and second-degree relatives of the spouses was comparable to the population frequency (0.5%), justifying the use of this sample as control. Positive family history was observed in 22.2% of probands and 8.24% of controls (Odd's Ratio 3.2, 95% Confidence Interval 2.12-4.73). An affected first-degree relative was observed in 7.5% of probands. The corresponding figure for GE, LRE and other epileptic syndromes were 10.2%, 5.8% and 5.12%, respectively. The segregation ratio for Juvenile Myoclonic Epilepsy (JME) (1:19) was higher than that for other types of Generalized Epilepsy (GE) (1:24) and Localization Related Epilepsy (LRE) (1:52). Prevalence of epilepsy among the first-degree relatives (1.96%) was greater than the square root of the population frequency (0.51%) and was higher than that for second-degree (1.24%) and third-degree (0.64%) relatives for the probands. Probands had higher parental consanguinity (13.07%) compared to controls (6.64%). The above factors support a complex inheritance. Genetic liability to epilepsy (heritability) is greater for GE (0.6) and significantly higher for JME (0.7) compared to LRE (0.4). A limitation of this study is that the inferences are based on a predominantly adult female proband sample but no gender specific differences were identified. CONCLUSIONS The observations of this study indicate complex inheritance and the liability values are useful for genetic counseling in the local population. Further studies involving more individuals from younger age group and male gender are envisaged.
Collapse
Affiliation(s)
- R Renuka Nair
- Kerala Registry of Epilepsy and Pregnancy, Departments of Neurology and Cellular and Molecular Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, India
| | | |
Collapse
|
18
|
Gu W, Sander T, Becker T, Steinlein OK. Genotypic association of exonic LGI4 polymorphisms and childhood absence epilepsy. Neurogenetics 2003; 5:41-4. [PMID: 14505228 DOI: 10.1007/s10048-003-0158-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Accepted: 07/14/2003] [Indexed: 11/28/2022]
Abstract
The LGI4 gene is located in a region linked to benign familial infantile convulsions (BFIC) and idiopathic generalized epilepsy. Screening of the LGI4 coding region in BFIC and childhood absence epilepsy (CAE) revealed several frequent exonic polymorphisms. A genotypic association was found for the c.1914GC --> AT polymorphism in 42 CAE patients compared with 110 population controls (chi2 = 6.66, df = 1, P = 0.01), providing evidence for a so far undetected susceptibility allele for CAE in the LGI4 region.
Collapse
Affiliation(s)
- Wenli Gu
- Institute of Human Genetics, Rheinische Friedrich Wilhelms University, University Hospital Bonn, Germany
| | | | | | | |
Collapse
|
19
|
Leniger T, Kananura C, Hufnagel A, Bertrand S, Bertrand D, Steinlein OK. A new Chrna4 mutation with low penetrance in nocturnal frontal lobe epilepsy. Epilepsia 2003; 44:981-5. [PMID: 12823585 DOI: 10.1046/j.1528-1157.2003.61102.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To identify and characterize the mutation(s) causing nocturnal frontal lobe epilepsy in a German extended family. METHODS Neuronal nicotinic acetylcholine receptor (nAChR) subunit genes were screened by direct sequencing. Once a CHRNA4 mutation was identified, its biophysical and pharmacologic properties were characterized by expression experiments in Xenopus oocytes. RESULTS We report a new CHRNA4 mutation, causing a alpha4-T265I amino acid exchange at the extracellular end of the second transmembrane domain (TM). Functional studies of alpha4-T265I revealed an increased ACh sensitivity of the mutated receptors. alpha4-T265I is associated with an unusual low penetrance of the epilepsy phenotype. Sequencing of the TM1-TM3 parts of the 1 known nAChR subunits did not support a two-locus model involving a second nAChR sequence variation. CONCLUSIONS nAChR mutations found in familial epilepsy are not always associated with an autosomal dominant mode of inheritance. alpha4-T265I is the first nAChR allele showing a markedly reduced penetrance consistent with a major gene effect. The low penetrance of the mutation is probably caused by unknown genetic or environmental factors or both.
Collapse
Affiliation(s)
- Tobias Leniger
- Department of Neurology, University of Essen, Essen, Germany
| | | | | | | | | | | |
Collapse
|