The long-term goal of this project is to understand how primary sequence directs the expression of eukaryotic genes and the structure and function of their encoded protein products. The human gene encoding galactose-1- phosphate uridyltransferase (GALT), an essential enzyme of the Leloir pathway of galactose metabolism, will be used is a model for study. Mutations in human GALT result in the potentially lethal disorder galactosemia, which is inherited as an autosomal recessive trait. Approximately 1/30,000 to 1/60,000 live-born infants suffer from severe, or """"""""classic"""""""" galactosemia, while about 1/11,000 infants exhibit milder, or """"""""variant"""""""" forms of this disease. Both the cDNA and gene encoding human GALT have recently been cloned, paving the way for molecular studies of the gene, the enzyme, and the disease. The specific objectives of this proposal are to identify and characterize essential functional and regulatory elements within human GALT.
The Specific Aims therefore are: (1) to analyze the molecular and biochemical effect(s) of known naturally occurring GALT mutations derived from patients with galactosemia, (2) to perform a directed mutational analysis of selected domains of human GALT, and (3) to clone and characterize the human GALT promoter. Naturally-occurring mutations in human GALT have been and will continue to be identified by direct-sequencing of PCR-amplified GALT cDNA and genomic sequences derived from galactosemia patients and their relatives. Site- specific mutations will be generated by oligonucleotide-directed mutagenesis of the cloned wildtype sequence. The effects of both naturally-occurring and directed mutations within the GALT coding region will be assessed using a yeast-based expression system for the human enzyme. This yeast-based system has already been established and shown to facilitate both genetic and biochemical manipulations of the human cDNA and enzyme. The human GALT promoter will be cloned by inverse or one-sided PCR extending from known sequences near the 5' end of the gene. Once cloned, the promoter will be characterized functionally by deletion analysis and mammalian cell transfection in the context of an established mammalian cell reporter gene construct. Combined, these studies should provide insights that are meaningful not only in terms of the basic science of eukaryotic gene expression and structure/function relationships, but also in terms of advancing the diagnosis, prognosis, and treatment of patients with galactosemia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
1R29DK046403-01
Application #
3464871
Study Section
Medical Biochemistry Study Section (MEDB)
Project Start
1993-08-01
Project End
1998-07-31
Budget Start
1993-08-01
Budget End
1994-07-31
Support Year
1
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Emory University
Department
Type
Schools of Medicine
DUNS #
042250712
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Jumbo-Lucioni, Patricia P; Hopson, Marquise L; Hang, Darwin et al. (2013) Oxidative stress contributes to outcome severity in a Drosophila melanogaster model of classic galactosemia. Dis Model Mech 6:84-94
Daenzer, Jennifer M I; Sanders, Rebecca D; Hang, Darwin et al. (2012) UDP-galactose 4'-epimerase activities toward UDP-Gal and UDP-GalNAc play different roles in the development of Drosophila melanogaster. PLoS Genet 8:e1002721
Ryan, Emily L; DuBoff, Brian; Feany, Mel B et al. (2012) Mediators of a long-term movement abnormality in a Drosophila melanogaster model of classic galactosemia. Dis Model Mech 5:796-803
McCorvie, Thomas J; Wasilenko, Jamie; Liu, Ying et al. (2011) In vivo and in vitro function of human UDP-galactose 4'-epimerase variants. Biochimie 93:1747-54
Sanders, Rebecca D; Sefton, Jennifer M I; Moberg, Kenneth H et al. (2010) UDP-galactose 4' epimerase (GALE) is essential for development of Drosophila melanogaster. Dis Model Mech 3:628-38
Kushner, Rebekah F; Ryan, Emily L; Sefton, Jennifer M I et al. (2010) A Drosophila melanogaster model of classic galactosemia. Dis Model Mech 3:618-27
Carney, Amanda E; Sanders, Rebecca D; Garza, Kerry R et al. (2009) Origins, distribution and expression of the Duarte-2 (D2) allele of galactose-1-phosphate uridylyltransferase. Hum Mol Genet 18:1624-32
Quimby, B B; Fridovich-Keil, J L (1997) Genetic approaches to biochemical questions: insights into the functional requirements of proline 185 in the active site of human galactose-1-phosphate uridylyltransferase. SAAS Bull Biochem Biotechnol 10:43-8
Wells, L; Fridovich-Keil, J L (1996) The yeast, Saccharomyces cerevisiae, as a model system for the study of human genetic disease. SAAS Bull Biochem Biotechnol 9:83-8
Elsas, L J; Langley, S; Steele, E et al. (1995) Galactosemia: a strategy to identify new biochemical phenotypes and molecular genotypes. Am J Hum Genet 56:630-9

Showing the most recent 10 out of 13 publications