GENETICS,MOLECULAR BIOLANDPHARMACOLOGICS--EPILEPSY GENES

Frings听原性癫痫（AGS）易感小鼠代表了一种感觉诱发反射癫痫的遗传模型，与DBA/2J AGS易感小鼠不同，它对声音诱发的癫痫发作表现出终身易感性。育种研究表明，Frings表型是一种单基因、高渗透常染色体隐性性状；然而，DBA/2J发作表型在起源上是多基因的，并且至少来自三个已知的基因座（即asp1， asp2和asp3）。我们将Frings小鼠的单基因听原性癫痫易感位点（mass1）定位到13号染色体上约2 cM的区域。这种简单的单基因小鼠癫痫模型中疾病基因的鉴定和表征将为更复杂的人类癫痫疾病的病理生理学提供新的见解。本提案中概述的四个具体目标将开始测试这一假设。特异性AIM - 1的精细定位研究将缩小mass - 1位点的范围，从而加快克隆进程。SPECIFIC AIM 2中概述的物理定位研究将为鉴定候选cdna和表达序列标签（est）提供基础，最终导致mass1基因的克隆。在SPECIFIC AIM 3中采用的育种策略是将mass1基因置于具有良好特征的AGS-resistant （C57BL）和AGS-sensitive （DBA/2J）背景上，构建新的同源小鼠菌株。这些新的同源菌株将有助于鉴定mass1基因与其他癫痫易感性和抗性基因之间的相互作用。将mass1基因置于不同遗传背景的药理学和表型后果将在SPECIFIC AIM 4中进行表征，其中将评估来自新同源菌株的小鼠的ags敏感性和癫痫阈值。这些研究将对遗传性癫痫的病理生理基础提供新的认识，并为合理开发抗癫痫药物和基因治疗提供新的分子靶点。

Frings audiogenic seizure (AGS)-susceptible mice represent a genetic model of sensory-evoked reflex epilepsy which, unlike the DBA/2J AGS-susceptible mouse, displays a life-long susceptibility to sound-induced seizures. Breeding studies have demonstrated that the Frings phenotype is a monogenic and highly penetrant autosomal recessive trait; whereas, the DBA/2J seizure phenotype is polygenic in origin and results from at least three known loci (i.e., asp1, asp2, and asp3). We have mapped the monogenic audiogenic seizure-susceptible (mass1) locus of the Frings mouse to an approximately 2 cM region on chromosome 13. The identification and characterization of the disease gene in this simple monogenic mouse epilepsy model will add new insight into the pathophysiology of more complex human seizure disorders. The four SPECIFIC AIMS outlined in this proposal will begin to test this hypothesis. The fine mapping studies of SPECIFIC AIM 1 will narrow the mass1 locus and thereby expedite the cloning process. The physical mapping studies outline in SPECIFIC AIM 2 will provide the foundation for the identification of candidate cDNAs and expressed sequence tags (ESTs) which will ultimately lead to the cloning of the mass1 gene. The breeding strategies employed in SPECIFIC AIM 3 will place the mass1 gene onto well-characterized AGS-resistant (C57BL) and AGS-sensitive (DBA/2J) backgrounds to construct new congenic mouse strains. These new congenic strains will be useful for identifying interactions between the mass1 gene and other seizure-susceptibility and seizure-resistance genes. The pharmacologic and phenotypic consequences of placing the mass1 gene on different genetic backgrounds will be characterized in SPECIFIC AIM 4 wherein the AGS-susceptibility and seizure-threshold of mice from the new congenic strains will be evaluated. These studies will provide new insight into the pathophysiologic basis of genetic epilepsy and provide new molecular targets that will be useful for rational antiepileptic drug development and gene therapy.