GENETIC ABBERATIONS IN HPRT DEFICIENCY

描述（由申请人提供）：Lesch Nyhan病（LND）是一种复杂的神经行为疾病，由x -连锁嘌呤回收途径酶次黄嘌呤鸟嘌呤磷酸核糖基转移酶（HPRT）缺乏引起。异常的神经表型包括发育迟缓、舞蹈症和自残行为。中枢神经系统缺陷与基底神经节缺乏多巴胺（DA）有关。小鼠HPRT敲除模型显示出相对正常的神经表型，但也显示纹状体中多巴胺缺乏。hprt缺失小鼠的中脑神经元原代培养显示多巴胺水平和多巴胺摄取减少。然而，迄今为止，对于HPRT缺乏导致多巴胺缺乏的机制的理解进展相对较少。为了确定次级基因在HPRT活性下游的潜在中介作用，我们对市售的MU74寡核苷酸小鼠基因组芯片进行了微阵列基因表达分析，该芯片询问了大约12,000个已知基因和ESTs。在对野生型和hprt缺失小鼠解剖纹状体基因表达的初步比较中，我们发现了少量基因和ESTs表达的可重复性变化，包括编码翻译起始因子IF2s3和IF3s1的基因，与纹状体多巴胺能神经元功能相关的基因，如调节酪氨酸羟化酶四氢生物蝶呤辅助因子表达的七蝶呤还原酶。酪蛋白激酶I-epsilon磷酸化DARPP-32，后者是多巴胺功能的主要纹状体靶点。我们还发现了一些与HPRT缺乏相关性尚不确定的其他cdna和ESTs的失调的初步证据。我们现在建议对正常小鼠和hprt缺陷小鼠进行更彻底的基因组表征，以检查这些基因在培养的中脑和纹状体DA神经元以及转基因和敲除小鼠中的异常表达对功能的影响。我们还计划通过基因转移技术确定这些功能的遗传校正的生化和神经递质效应。

DESCRIPTION (provided by applicant): Lesch Nyhan disease (LND) is a complex neurobehavioral disease caused by deficiency of the X-linked purine salvage pathway enzyme hypoxanthine guanine phosphoribosyl transferase (HPRT). The abnormal neurological phenotype includes retardation, choreoathetosis and self-injurious behavior. The CNS defects are associated with a basal ganglia deficiency of dopamine (DA). A mouse HPRT knockout model displays a relatively normal neurological phenotype but also shows a deficiency of dopamine in the striatum. Primary cultures of midbrain neurons from HPRT-deficient mice demonstrate a reduction of dopamine levels and dopamine uptake. However, to date there has been relatively little progress toward an understanding of the mechanisms by which HPRT deficiency leads to dopamine deficiency. To identify the potential intermediary role of secondary genes functionally downstream of HPRT activity, we have used microarray gene expression analysis on commercially available MU74 oligonucleotide mouse genome chips that interrogate approximately 12,000 known genes and ESTs. In preliminary comparisons of gene expression in dissected striata from wild type and HPRT-deficient mice, we have detected reproducible changes in the expression of a small number of genes and ESTs, including those encoding translation initiation factors IF2s3 and IF3s1, genes associated with striatal dopaminergic neuron function such as sepiapterin reductase that regulates expression of the tetrahydrobiopterin co-factor of tyrosine hydroxylase, and casein kinase I-epsilon that phosphorylates DARPP-32, the principal striatal target for dopamine function. We have also found preliminary evidence for dysregulation of a number of other cDNAs and ESTs of still uncertain relevance to HPRT deficiency. We propose now to complete a more thorough genome characterization of normal and HPRT-deficient mice, to examine the functional effects of aberrant expression of these genes in cultured midbrain and striatal DA neurons and in transgenic and knockout mice. We also plan to determine the biochemical and neurotransmitter effects of genetic correction of these functions by gene transfer techniques.