Mutation analysis and characterization of alternative splice variants of the Wilson disease gene ATP7B
Journal
Hepatology
Journal Volume
52
Journal Issue
5
Pages
1662-1670
Date Issued
2010
Author(s)
Chih-Chao Yang
Abstract
Wilson disease is a copper metabolism disorder caused by mutations in ATP7B, a copper-transporting adenosine triphosphatase. A molecular diagnosis was performed on 135 patients with Wilson disease in Taiwan. We identified 36 different mutations, eight of which were novel: five missense mutations (Ser986Phe, Ile1348Asn, Gly1355Asp, Met1392Lys, and Ala1445Pro), one deletion (2810delT) in the coding region, and two nucleotide substitutions (-133A→C and -215A→T) in the promoter region. These mutations were not observed in 100 control subjects and reduced the activity of the mutated protein by at least 50% when compared with wild-type ATP7B. In addition to exon 8, our data indicate another mutation hotspot in exon 12 where 9.62% of all mutations occurred. An alternative splice variant of ATP7B lacking exon 12 was observed in one patient who had a homozygous 2810delT mutation and very mild clinical symptoms. Clinical examination and functional characterization of alternative splice variants of ATP7B lacking exon 12 showed that they retained 80% of their biological activity. The 2810delT mutation increased the expression of these variants, which may have explained the mild symptoms in the patient with the 2810delT mutation. We also discovered that treating liver cancer cells with a Na+/H+ exchanger inhibitor, 5-(N-ethyl-N-isopropyl)-amiloride, significantly enhanced the expression of the alternative splice variant of ATP7B lacking exon 12. Conclusion: This study suggests a novel therapeutic strategy for patients with mutations in exon 12. ? 2010 American Association for the Study of Liver Diseases.
SDGs
Other Subjects
5 (n ethyl n isopropyl)amiloride; alanine; asparagine; aspartic acid; isoleucine; lysine; methionine; phenylalanine; proline; serine; Wilson disease protein; 5' untranslated region; alternative RNA splicing; amino acid substitution; animal cell; article; biological activity; cancer cell; clinical examination; controlled study; exon; female; gene identification; genotype phenotype correlation; homozygote; human; liver cancer; major clinical study; missense mutation; mutational analysis; nonhuman; priority journal; promoter region; Taiwan; wild type; Wilson disease; Adenosine Triphosphatases; Alternative Splicing; Amino Acid Substitution; Apoptosis; Cation Transport Proteins; Copper; Exons; Genes, Reporter; Genetic Variation; Hepatolenticular Degeneration; Homozygote; Humans; Mutagenesis, Site-Directed; Mutation, Missense; Polymorphism, Single Nucleotide; Promoter Regions, Genetic; Sequence Deletion
Type
journal article