Altered Function of a GABA-A receptor epilepsy mutation

GABA-A 受体癫痫突变的功能改变

• 批准号: 7225577
• 负责人: MATHEW V JONES
• 金额: $ 34.36万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7225577
• 关键词: Accounting; Address; Affect; Agonist; Alleles; Animal Model; Appendix; Arginine; Benzodiazepines; Binding Sites; Brain; Cells; Chemical Stimulation; Chromosome Pairing; Data; Epilepsy; Febrile Convulsions; Frequencies; Future; GABA-A Receptor; GABA-A receptor gamma2 subunit; Generalized Epilepsy; Genes; Genetic; Glutamine; Hippocampus (Brain); Human; Inhibitory Synapse; Kinetics; Knock-in Mouse; Knowledge; Lead; Link; Measurement; Measures; Membrane; Methods; Mus; Mutate; Mutation; Neurons; Pharmacology; Physiological; Point Mutation; Principal Investigator; Property; Rate; Research; Role; Seizures; Slice; Sodium Chloride; Synapses; Synaptic Receptors; Synaptic Transmission; Syndrome; System; Testing; Thalamic structure; Transgenic Mice; Transgenic Organisms; base; desensitization; design; gamma-Aminobutyric Acid; human PTCH2 protein; molecular modeling; mutant; novel; patch clamp; postsynaptic; presynaptic; programs; receptor; receptor function; relating to nervous system; research study; response; synaptic inhibition; transmission process

A genetic epilepsy syndrome called GEFS+ (Generalized Epilepsy with Febrile Seizures plus) is now known to be a common form of genetic epilepsy. At least three of the identified GEFS+ mutations occur in the gene encoding the gamma2 subunit of the GABA A receptor, responsible for most synaptic inhibition in the brain. One such mutation, gamma2(R43Q), replaces a highly conserved arginine residue with a glutamine. Molecular modeling predicts that this substitution may disrupt salt bridge interactions between the gamma2 and beta2 subunits, which may be critical for normal receptor function and pharmacology. Our initial studies of human gamma2(R43Q)-containing GABA A receptors reveal dramatic kinetic changes, including enhanced receptor desensitization, that could contribute to GEFS+ by causing a "rundown" in synaptic inhibition during high intensity neural activity. The overall Objective of the proposed research is to understand how alterations in the region of the GABAA receptor near gamma2(R43Q) change receptor function and contribute to epilepsy. The Specific Aims are to 1) determine the biophysical mechanism of the changes in receptor function caused by the mutation, by studying channel kinetics in excised membrane patches, 2) determine the structural basis of the changes by examining point mutations designed to a) rescue the predicted salt bridge formation and b) to further purturb it in controlled manner, 3) determine the impact of the gamma2(R43Q) mutation on synaptic transmission in transgenic mice that express the mutant subunit in place of the wild type allele, and 4) determine whether synapses undergo enhanced desensitization as a result of the mutation, and whether this causes increased network hyperexcitability in cortical, thalamic and hippocampal brain slices. The knowledge gained from these studies will 1) provide valuable information about the structural/functional role of the receptor region affected by the epilepsy mutation gamma2(R43Q), 2) allow us to better understand critical aspects of inhibition that are causally related to epilepsy, 3) provide an unprecedented opportunity to study the physiological role of GABA A receptor desensitization at functional synapses and in network excitability; and 4) further develop a novel animal model for future studies of GEFS+ epilepsy.

遗传性癫痫综合征称为GEFS+（全身性癫痫伴发热性癫痫发作），现在已知是遗传性癫痫的一种常见形式。至少有三个已确定的GEFS+突变发生在编码gabaa受体的gamma2亚基的基因上，gabaa受体负责大脑中大多数突触抑制。其中一个突变，伽马2(R43Q)，用谷氨酰胺取代了高度保守的精氨酸残基。分子模型预测，这种取代可能会破坏γ - 2和β - 2亚基之间的盐桥相互作用，这可能对正常受体功能和药理学至关重要。

项目成果

Increased thalamic inhibition in the absence seizure prone DBA/2J mouse.

缺乏癫痫发作倾向的 DBA/2J 小鼠的丘脑抑制增加。

• DOI: 10.1111/j.1528-1167.2008.01536.x
• 发表时间: 2008
• 期刊: Epilepsia
• 影响因子: 5.6
• 作者: Tan,HeneuO;Reid,ChristopherA;Chiu,Cindy;Jones,MathewV;Petrou,Steven
• 通讯作者: Petrou,Steven

Brain uptake of diazepam and phenytoin in a genetic animal model of absence epilepsy.

失神性癫痫遗传动物模型中地西泮和苯妥英的大脑摄取。

• DOI: 10.1111/j.1440-1681.2010.05362.x
• 发表时间: 2010
• 期刊: Clinical and experimental pharmacology & physiology
• 影响因子: 2.9
• 作者: Nicolazzo,JosephA;Steuten,JessicaA;Charman,SusanA;Taylor,Nerida;Davies,PhilipJ;Petrou,Steven
• 通讯作者: Petrou,Steven