New Splicing Variants of the Murine Damaged DNA Binding 2

Abstract

Damaged DNA binding (DDB) protein is an important gene in the repair of damaged DNA. DDB is a heterodimer (DDB1 and DDB2) protein, murine DDB2 has 10 exons about 1.5kb in size (Genbank Accession No. AY027937). Here we identified five DDB2 variants (M1-M5) from various mouse tissues that are generated by alternative splicing. We used reverse transcription-PCR (RT-PCR) to identify splicing variants and isolated PCR products using an agarose-gel PCR purification kit. All isolated PCR products were cloned and the structure of splicing variants was confirmed by sequencing. The first splicing variant M1 was generated by omission of exon 4. The second splicing variant M2, by omission of exons 4-5. The third variants M3 was generated by omission from the middle of exon 1 to exon 6 and was expressed in the heart. Fourth variants M4 was generated by omission of exon 2 and exons 4-7. M5, the last splicing variant was generated by omission of exons 4-7. M4 and M5 were expressed in the spleen. Analysis of tissue distribution by RT-PCR indicates that M1 is most highly expressed in the mouse brain. These results indicated that murine DDB2 has five splicing variants and splicing variants expression patterns were different depending on mouse tissue. Further functional studies of each splicing variants will provide more information about the molecular mechanism of DDB2 function and DDB2 gene expression regulation.