Abstract
Human eosinophil-derived neurotoxin (EDN, RNase2) and human eosinophil cationic protein (ECP, RNase3) belong to the ribonuclease A (RNase A) superfamily, and the duplicated edn and ecp genes are located in the q24-q31 region of chromosome 14. Multiple sequence alignment of upstream 1 kb region of human edn and ecp showed 92% identity, but a major difference was a 34-nucleotide (34-nt) element (-81/-48) only appeared in the edn promoter. However, some minor differences between edn and ecp promoters mainly located in six different regions might also be involved. In this study, luciferase reporter assay was employed to find out which minor region also plays the role to regulate the promoter activity, and a mount of decrease in edn promoter activity was detected when region 2 sequence mutated to the same with ecp. Electrophoretic mobility shift assays (EMSA) and supershift results show that the transcription factor HNF4 could bind to region 2 of edn promoter. Greatly decrease of promoter activity was detected in deletion of region 2 in edn promoter results, so this region might play important role with edn gene. In previous research, edn could be regulated by Sp1 and MAZ depending on that binding to 34nt. Combining this study, edn gene expression might be co-regulated by interaction between its promoter and transcription factors HNF4, Sp1 and MAZ.