Objective   To investigate the role of a cis-acting element

cell cycle genes homology region (CHR)

in the transcriptional regulation of human NFBD1 gene (a nuclear factor with BRCT domain 1) by conducting a site-directed mutagenesis analysis on the element in human NFBD1 promoter region.    Methods   Wild type of NFBD1 promoter reporter

NFBD1-PS1-325

was used as template to make CHR mutant by using PCR based site-directed mutagenesis. Dual luciferase reporter assay was used to determine promoter reporter activity. Adiamycin treatment was employed to investigate the role of CHR in the transcriptional downregulation of NFBD1 after DNA damage.    Results   Site-directed mutagenesis of CHR caused a significant decrease in NFBD1 promoter activity

and also attenuated the transcriptional down-regulation of NFBD1 after DNA damage.    Conclusion   CHR element might be involved in both basic transcriptional regulation and transcriptional downregulation of NFBD1 after DNA damage.