Identification of an NF-Y/HMG-I(Y)-binding site in the human IL-10 promoter

The cis-acting elements and transcriptional factors that control interleukin 10 (IL-10) promoter activity remain to be clarified. In this report, by performing electrophoresis mobility shift assay (EMSA) with nuclear extracts from the Raji B cell line, the nuclear factor Y (NF-Y) was found to be capable of binding to a CCAAT box-containing region between the −215 and −192 bps (the −215/−192 region), relative to the transcription initiation site, in the human IL-10 promoter. The binding of NF-Y to the promoter appears to be enhanced by the presence of HMG-I(Y), since anti-HMG-I(Y) antibody diminished the NF-Y-binding activity in EMSA. Two T nucleotides at −192 and −193 bps were found to be critical for the binding of NF-Y and HMG-I(Y) to the −215/−192 promoter region, suggesting the possibility that HMG-I(Y) binds to the AT-rich promoter region downstream of the CCAAT box at the −210/−199 region. These findings suggest that NF-Y and HMG-I(Y) may play an important role in regulating the IL-10 promoter activity in B cells.