title: Human DDB2 splicing variants are dominant negative inhibitors of UV-damaged DNA repair.
abstract: Damaged DNA-binding protein (DDB) is a heterodimer (DDB1 and DDB2), which is implicated in the repair of UV-irradiated DNA damage. Here we have identified four DDB2 variants from HeLa cells (D1-D4) that are generated by alternative splicing. Analysis of tissue distribution by RT-PCR indicates that D1 is the most highly expressed in human brain and heart. A DNA repair assay revealed that both D1 and D2 are dominant negative inhibitors. Electrophoresis mobility shift assays indicated that D1 and D2 are not part of the damaged DNA-protein complex. Co-immunoprecipitation studies show that DDB2-WT interacts with D1 and itself. Nuclear import of DDB1 was less induced by transfection with D1 than WT. Based on these results, D1 and D2 are dominant negative inhibitors of DNA repair, which is probably due to disruption of complex formation between DDB1 and DDB2-WT and of DDB1 nuclear import.
authors.affiliation: Department of Biochemistry, Jichi Medical School, Tochigi, Japan.
authors.forename: Taeko
authors.initials: T
authors.lastname: Inoki
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamagami
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Inoki
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Tsuru
authors.forename: Toshiro
authors.initials: T
authors.lastname: Hamamoto
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kagawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Mori
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
mesh_terms: D001483:Base Sequence; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism; D004249:DNA Damage; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D021381:Protein Transport; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014466:Ultraviolet Rays
chemical_list: C117669:DDB2 protein, human; D017931:DNA Primers; D004268:DNA-Binding Proteins