GENETICS,MOLECULAR BIOLANDPHARMACOLOGICS--EPILEPSY GENES

Frings听源性癫痫(AGS)敏感小鼠代表了一种感觉诱发反射性癫痫的遗传模型，与DBA/2J AGS敏感小鼠不同，它对声音诱发癫痫表现出终生易感性。育种研究表明，Frings表型是一种单基因、高渗透性的常染色体隐性遗传性状，而DBA/2J癫痫表型是多基因遗传，至少由3个已知基因座(即asp1、asp2和asP3)决定。我们已经将Frings小鼠的单基因听源性癫痫易感(MAS1)基因定位在13号染色体上大约2 cM的区域。在这个简单的单基因小鼠癫痫模型中，疾病基因的鉴定和特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。这项提案中概述的四个具体目标将开始检验这一假设。对特定AIM1的精细定位研究将缩小Mass1基因座的范围，从而加快克隆进程。在特定的AIM 2中的物理定位研究大纲将为鉴定候选的cDNA和表达序列标签(EST)提供基础，最终导致Mass1基因的克隆。在特定的AIM 3中采用的育种策略将把Mass1基因置于具有良好特性的AGS抗性(C57BL)和AGS敏感(DBA/2J)背景上，以构建新的同源小鼠品系。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癫痫抵抗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特定的AIM 4中表征，其中将评估来自新的同源品系的小鼠的AGS敏感性和癫痫阈值。这些研究将为遗传性癫痫的病理生理学基础提供新的见解，并为合理的抗癫痫药物开发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.