A novel c.-22T>C mutation in <it>GALK1 </it>promoter is associated with elevated galactokinase phenotype

• Main Authors: Kim Jin Q (Author), Park Kyoung (Author), Kim Yoon-Kyoung (Author), Park Hyung-Doo (Author), Song Young-Han (Author), Song Junghan (Author)
• Format: Book
• Published: BMC, 2009-03-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.1186/1471-2350-10-29; 1471-2350
• Keywords: Internal medicine; RC31-1245; Genetics; QH426-470
• Source: BMC Medical Genetics, Vol 10, Iss 1, p 29 (2009)

<p>Abstract</p> <p>Background</p> <p>Many genetic variations of <it>GALK1 </it>have been identified in the patients with galactokinase (GALK1) deficiency. However, the molecular characteristics of <it>GALK1 </it>in individuals with elevated GALK1 activity are relatively unknown.</p> <p>Methods</p> <p>We investigated the relationship between elevated GALK1 activity and the molecular <it>GALK1 </it>gene variations, and the molecular mechanism underlying elevated GALK1 activity. PCR products from 63 subjects, without any attenuation of galactose degradation enzymes, were sequenced to screen for nucleotide alterations in the <it>GALK1 </it>promoter.</p> <p>Results</p> <p>Three nucleotide substitutions were identified: c.-179A>G, c.-27A>C, and c.-22T>C. With respect to the c.-22T>C mutation, GALK1 activity in 13 subjects with the T/C or C/C genotype was significantly higher than those in 50 subjects with the T/T genotype (p < 0.001). The dual luciferase reporter assay in Hep3B cells showed that the luciferase activity with the <it>GALK1 </it>promoter with the c.-22C mutant allele increased approximately 2.5-fold, compared to that with the c.-22T. A specific DNA-protein complex was observed in an electrophoretic mobility shift assay, with slightly higher affinity to c.-22C than to c.-22T.</p> <p>Conclusion</p> <p>The c.-22T>C mutation, which was observed frequently in individuals with elevated GALK1 activity, increased the expression of a reporter gene through enhanced binding of a currently unidentified nuclear protein. These results suggest that the elevated GALK1 activity resulted from enhanced gene expression, due to nucleotide variation within <it>GALK1 </it>promoter.</p>