GENETIC ABBERATIONS IN HPRT DEFICIENCY

描述（由申请方提供）：莱希尼汉病（LND）是一种由X-连锁嘌呤补救途径酶次黄嘌呤鸟嘌呤磷酸核糖转移酶（HPRT）缺乏引起的复杂神经行为疾病。异常的神经系统表型包括发育迟缓、舞蹈徐动症和自伤行为。中枢神经系统缺陷与基底神经节多巴胺（DA）缺乏有关。小鼠HPRT敲除模型显示相对正常的神经学表型，但也显示纹状体中多巴胺缺乏。HPRT缺陷小鼠中脑神经元的原代培养物显示多巴胺水平和多巴胺摄取减少。然而，迄今为止，对HPRT缺乏导致多巴胺缺乏的机制的理解进展相对较小。为了确定HPRT活性下游功能性次级基因的潜在中介作用，我们使用微阵列基因表达分析对市售MU 74寡核苷酸小鼠基因组芯片，询问约12，000个已知基因和EST。在对野生型和HPRT缺陷型小鼠的解剖纹状体中的基因表达进行初步比较时，我们检测到少量基因和EST表达的可重复变化，包括编码翻译起始因子IF 2s 3和IF 3s 1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的四氢生物蝶呤辅因子表达的sepiapterin还原酶，和酪蛋白激酶I-cAMP，其磷酸化DARPP-32，多巴胺功能的主要纹状体靶点。我们还发现了一些其他cDNA和EST的调控异常的初步证据，这些cDNA和EST与HPRT缺陷的相关性仍然不确定。我们现在建议完成一个更彻底的基因组特征的正常和HPRT缺陷小鼠，研究这些基因的异常表达在培养的中脑和纹状体DA神经元和转基因和基因敲除小鼠的功能影响。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的生物化学和神经递质效应。

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.