The urea cycle is the major pathway for detoxification of ammonia in mammals. Arginase I deficiency is thought to be the least common of the urea cycle disorders and results in hyperargininemia. In humans, deficiency of this enzyme is characterized clinically by progressive mental impairment, spasticity, growth retardation, and periodic episodes of hyperammonemia. This proposal is two-fold: 1) to develop gene-based correction of arginase deficiency with viral vectors and to closely examine corrected animals behaviorally and biochemically;and 2) to evaluate the role elevated arginine and related metabolites (beyond just ammonia) have on the developing brain and development of mental retardation in arginase deficiency. Preliminary data: Our research group has: 1) constructed and characterized the arginase I knockout mouse;2) demonstrated at least short-term (if not longer) correction and rescue with recombinant helper-dependent adenoviral vectors and adeno-associated viral vectors;3) demonstrated that knockout mouse neurons have a higher percentage of cells in the S phase of the cell cycle;4) shown that differentiated neurons from knockout mice have a more mature morphology;and 5) shown that knockout neurons demonstrate induction of genes related to protection from oxidative damage.
In Aim 1, recombinant viral vectors will be used to rescue mice from lethality and to obtain a better understanding of the challenges facing neonatal gene therapy that involve rapid cellular proliferation and potential loss with episomal vs. integrated vectors.
In Aim 2, the effect of hyperargininemia on the nervous system will be examined in vitro along with GABA and glutamine synthesis/release, and extensive microarray analysis.
In Aim 3, the effect of hyperargininemia on the nervous system will be examined in vivo along with GABA and glutamine synthesis/release, guanidino compound determination, and the role that nitric oxide and its metabolites may have on nervous system injury. Successful completion of the proposed studies will provide a molecular understanding of the mechanism of injury to the brain in arginase I deficiency and related disorders. In addition, it is expected that a gene replacement strategy will have been developed for arginase deficiency through these studies and that the information obtained in treating neonates that have developing tissues undergoing rapid proliferation will be applicable to other inborn errors of metabolism.

Public Health Relevance

to Public Health This project will further elucidate the role arginase plays in health and the mechanisms of disease and neurological insult in its deficiency. In addition, it will be directed at developing a gene replacement strategy for this disorder. Neonatal gene therapy has particular challenges related to rapid cellular proliferation and this proposal will examine gene therapy in that context with application to how such strategies can cure other similar diseases that afflict newborns.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
3R01NS071076-04S1
Application #
8730900
Study Section
Gene and Drug Delivery Systems Study Section (GDD)
Program Officer
Morris, Jill A
Project Start
2010-09-17
Project End
2015-07-31
Budget Start
2013-08-01
Budget End
2014-07-31
Support Year
4
Fiscal Year
2013
Total Cost
$57,277
Indirect Cost
$8,859
Name
University of California Los Angeles
Department
Surgery
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Hu, Chuhong; Kasten, Jennifer; Park, Hana et al. (2014) Myocyte-mediated arginase expression controls hyperargininemia but not hyperammonemia in arginase-deficient mice. Mol Ther 22:1792-802
Kasten, Jennifer; Hu, Chuhong; Bhargava, Ragini et al. (2013) Lethal phenotype in conditional late-onset arginase 1 deficiency in the mouse. Mol Genet Metab 110:222-30
Lee, E K; Hu, C; Bhargava, R et al. (2013) AAV-based gene therapy prevents neuropathology and results in normal cognitive development in the hyperargininemic mouse. Gene Ther 20:785-96
Hu, Chuhong; Cela, Racel G; Suzuki, Masataka et al. (2011) Neonatal helper-dependent adenoviral vector gene therapy mediates correction of hemophilia A and tolerance to human factor VIII. Proc Natl Acad Sci U S A 108:2082-7