Galactosemia: deletion in the 5' upstream region of the GALT gene reduces promoter efficiency.
Galactosemia is a metabolic disorder caused by a defect in the galactose-1-phosphate uridyltransferase (GALT) enzyme. In previous studies, we have shown that the presence of a deletion in the 5' upstream (promoter) region of the GALT gene is associated with the Duarte (D2) allele. In the present study, by using a promoter fusion assay we provide direct evidence that a GTCA deletion located in position -119/-116 of the GALT gene (considered in relation to the translational start site) decreases transcription of a reporter gene to about 55% compared with a normal "healthy" promoter transfected into human hepatocyte HepG2 cells. This result coincides well with previously published biochemical data showing 50% GALT-gene activity in Duarte (D2) galactosemia patients. By transfecting the same promoters (normal and deleted) into mouse NIH/3T3 cells, we show that the GTCA motif in the promoter region of the GALT gene was conserved throughout evolution. We conclude that the -119/-116delGTCA promoter mutation is a crucial factor in reduction of Duarte allele enzyme activity.
Trbusek
M
M
Department of Biochemical and Molecular Genetics, Research Institute of Child Health, Cernopolni 9, 662 62 Brno, Czech Republic.
Francová
H
H
Kozák
L
L
D016475:3T3 Cells; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D005693:Galactosemias / Q000201:enzymology* / Q000235:genetics*; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000235:genetics; D051379:Mice; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D014162:Transfection; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase / Q000235:genetics*
D017931:DNA Primers; D008156:Luciferases; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase