Cloning of the flap endonuclease-1 gene in Bombyx mori and identification of an antiapoptotic function.

The flap endonuclease-1 (FEN-1) gene is involved in DNA replication and repair, and it maintains genomic stability as well as the accuracy of DNA replication under normal growth conditions. However, FEN-1 also plays an important role in apoptosis and cancer development. We cloned the BmFEN-1 gene from Bombyx mori, which was 1343 bp in length and possessed an 1143 bp ORF (123-1266). It consists of seven introns and eight exons that encode a protein with 380 amino acids that has the typical XPG domain. The N-terminal motif is located at amino acids 95-105, and the proliferating cell nuclear antigen interaction motif is located at amino acids 337-344. RNA interference-mediated reduction of BmFEN-1 expression induced cell cycle arrest in S phase in BmE-SWU1 cells. These results suggest that BmFEN-1 can inhibit apoptosis and promote cell proliferation.