In humans, deficiency of galactose-1-phosphate uridyltransferase (GALT) caused by mutations in the GALT gene leads to a potentially lethal disease, classic galactosemia. If galactose is not withdrawn from the diet of affected infants within five to nince days of life, some newborns die of hepatic failure and Escherichia coli sepsis. Although all 50 states in the U.S. include this metabolic disorder in newborn screening programs and a galactose-restricted diet prevents neonatal death in some affected infants, many surviving patients develop debilitating complications including growth restriction, premature ovarian failure, speech dyspraxia, ataxia, and other neurological deficits. The long-term goal of this project is to develop more effective therapies for patients with classic galactosemia. Earlier, the investigators defined the structure-function basis of specific GALT mutations and established genotype-phenotype relationships for disease severity and outcome. Using patient cells that are homozygous for the Q188R-GALT mutation, they recently showed that galactose insult to these cells resulted in accumulation of galactose-1-phosphate (Gal-1-P) and manifestation of endoplasmic reticulum (ER) stress prior to cell death. Through serendipity, they also discovered that supplementation of specific antioxidants protected these cells from galactose toxicity. They hypothesize that patient genotypes, which dictate the amount of Gal-1-P accumulated, define the degree of cellular toxicity via mechanisms involving ER stress and oxidative stress. To test this hypothesis, the investigators propose, in Specific Aim 1, to derive diploid fibroblast cells strains from galactosemic patients homozygous for three different mutant alleles: Q188R, S135L, and ?5kb. They will characterize these cell strains and use them to test the efficacies of novel therapies;
in Specific Aim 2, to discover small molecule inhibitors for human galactokinase (GALK), the enzyme responsible for the production of Gal-1-P, and to test their efficacy in preventing ER stress in GALT-deficient cells stratified by genotypes;and in Specific Aim 3, to delineate the molecular mechanisms by which antioxidant supplementation protects GALT-deficient cells from galactose toxicity, stratified by genotype.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
3R01HD054744-04S1
Application #
7932658
Study Section
Special Emphasis Panel (ZHD1-MRG-C (03))
Program Officer
Urv, Tiina K
Project Start
2009-09-30
Project End
2011-09-29
Budget Start
2009-09-30
Budget End
2011-09-29
Support Year
4
Fiscal Year
2009
Total Cost
$168,856
Indirect Cost
Name
University of Utah
Department
Pediatrics
Type
Schools of Medicine
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Tang, Manshu; Siddiqi, Anwer; Witt, Benjamin et al. (2014) Subfertility and growth restriction in a new galactose-1 phosphate uridylyltransferase (GALT) - deficient mouse model. Eur J Hum Genet 22:1172-9
Tang, M; Odejinmi, S I; Vankayalapati, H et al. (2012) Innovative therapy for Classic Galactosemia - tale of two HTS. Mol Genet Metab 105:44-55
Odejinmi, Sina I; Rascon, Rafael G; Chen, Wyman et al. (2012) Formal Synthesis of 4-diphosphocytidyl-2-C-methyl D-erythritol From D-(+)-Arabitol. Tetrahedron 68:8937-8941
Tang, Manshu; Facchiano, Angelo; Rachamadugu, Rakesh et al. (2012) Correlation assessment among clinical phenotypes, expression analysis and molecular modeling of 14 novel variations in the human galactose-1-phosphate uridylyltransferase gene. Hum Mutat 33:1107-15
Tang, M; Odejinmi, S I; Allette, Y M et al. (2011) Identification of novel small molecule inhibitors of 4-diphosphocytidyl-2-C-methyl-D-erythritol (CDP-ME) kinase of Gram-negative bacteria. Bioorg Med Chem 19:5886-95
Odejinmi, Si; Rascon, Rg; Tang, M et al. (2011) Structure-activity analysis and cell-based optimization of human galactokinase inhibitors. ACS Med Chem Lett 2:667-672
Tang, M; Wierenga, K; Elsas, L J et al. (2010) Molecular and biochemical characterization of human galactokinase and its small molecule inhibitors. Chem Biol Interact 188:376-85
Lai, Kent; Elsas, Louis J; Wierenga, Klaas J (2009) Galactose toxicity in animals. IUBMB Life 61:1063-74
Wierenga, Klaas J; Lai, Kent; Buchwald, Peter et al. (2008) High-throughput screening for human galactokinase inhibitors. J Biomol Screen 13:415-23
Syriopoulos, C; Panayotarou, A; Lai, K et al. (2008) Transcriptomic analysis of Saccharomyces cerevisiae physiology in the context of galactose assimilation perturbations. Mol Biosyst 4:937-49

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