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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS044544-03
Application #
6881411
Study Section
Special Emphasis Panel (ZRG1-BDCN-5 (01))
Program Officer
Murphy, Diane
Project Start
2003-04-01
Project End
2008-03-31
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
3
Fiscal Year
2005
Total Cost
$360,999
Indirect Cost
Name
University of California San Diego
Department
Pediatrics
Type
Schools of Medicine
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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