A GENETIC ANALYSIS OF MINIBRAIN KINASE IN C. ELEGANS

本研究计划的目标是确定涉及小脑激酶 (mnbK) 的分子通路，无论是在正常神经元功能还是在唐氏综合症的认知缺陷中。对 21 号染色体部分三体性的研究表明，相当一部分唐氏综合症表型是由 21g22.2 区域的 2 Mb 区域引起的； mnbK 定位于该基因组区域。 mnbK 在小鼠体内的过度表达会导致严重的学习和记忆缺陷，这与唐氏综合症的认知缺陷密切相关。目前，mnbK 的底物和调节剂尚不清楚。为了阐明这一途径，将对秀丽隐杆线虫 mnbK 同源物 mbk-1 和 mbk-2 进行研究。 我建议表征 mbk 基因产物的表达和亚细胞定位，通过化学诱变结合群体 PCR 生成无效等位基因，并通过过度表达野生型和激活的基因产物来模拟 Down 条件。作为确定 MBK 活性焦点的工具，四环素依赖性反式激活系统将适用于秀丽隐杆线虫，该系统允许在时间和空间上调节基因表达。将测试候选基因以确定它们是否属于 mbk 途径，并将进行先导抑制子和/或增强子筛选，以公正的方式识别上游和下游组件。

The goal of this research proposal is to identify molecular pathways involving minibrain kinase (mnbK), both in normal neuronal function and in the cognitive defects of Down syndrome. Studies of partial trisomy of chromosome 21 suggest that a considerable portion of the Down syndrome phenotype result from a 2-Mb region at the 21g22.2 region; mnbK localizes to this genomic region. Overexpression of mnbK in mice causes severe defects in learning and memory, strongly implicating mnbK in the cognitive defects of Down syndrome. Currently, the substrates and regulators of mnbK are unknown. To elucidate this pathway, the Caenorhabditis elegans mnbK homologues mbk-1 and mbk-2, will be investigated. I propose to characterize the expression and subcellular localization of the mbk gene products, generate null alleles via chemical mutagenesis coupled with population PCR, and simulate the Down condition by overexpressing the wildtype and activated gene products. As a tool for determing the focus of MBK activity, the tetracycline-dependent transactivator system will be adapted to C. elegans, a system that permits temporally and spatially regulated gene expression. Candidate genes will be tested to determine if they belong to a mbk pathway, and pilot suppressor and/or enhancer screens will be performed to identify upstream and downstream components in an unbiased manner.