GENETIC ABBERATIONS IN HPRT DEFICIENCY

描述(申请人提供)：Lesch Nyhan病(LND)是一种复杂的神经行为疾病，由X-连锁嘌呤挽救途径酶次黄嘌呤鸟嘌呤磷酸核糖转移酶(HPRT)缺乏引起。异常的神经表型包括发育迟缓、舞蹈动作障碍和自伤行为。中枢神经系统缺陷与基底节多巴胺(DA)缺乏有关。小鼠HPRT基因敲除模型显示出相对正常的神经学表型，但也显示纹状体中缺乏多巴胺。HPRT缺陷小鼠中脑神经元的原代培养显示出多巴胺水平和多巴胺摄取的减少。然而，到目前为止，在理解HPRT缺乏导致多巴胺缺乏的机制方面进展相对较少。为了确定HPRT活性下游的次级基因的潜在中介作用，我们在商业上可用的MU74寡核苷酸小鼠基因组芯片上使用了微阵列基因表达分析，这些芯片询问了大约12,000个已知基因和EST。在对野生型和HPRT缺陷小鼠的纹状体基因表达的初步比较中，我们检测到少数基因和EST的表达发生了可重复的变化，包括那些编码翻译起始因子IF2s3和IF3s1的基因，这些基因和EST与纹状体多巴胺能神经元功能相关的基因，如调节酪氨酸羟基酶的四氢生物蝶呤辅助因子表达的sepiapterin还原酶，以及使DARPP-32磷酸化的酪蛋白激酶I-epsilon，DARPP-32是纹状体多巴胺功能的主要靶标。我们还发现了一些其他cDNA和EST调控失调的初步证据，这些cDNA和EST与HPRT缺乏症的相关性仍然不确定。我们现在建议完成更全面的正常和HPRT缺陷小鼠的基因组特征，以检测这些基因在培养的中脑和纹状体DA神经元以及在转基因和基因敲除小鼠中异常表达的功能影响。我们还计划通过基因转移技术来确定这些功能的遗传校正对生化和神经递质的影响。

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.