NF-Y is essential for the recruitment of RNA polymerase II and inducible transcription of several CCAAT box-containing genes.

Osteoclast differentiation factor (ODF)/receptor activator of NF-kappaB ligand is essential for inducing the differentiation of mature osteoclasts. We find that nuclear factor Y (NF-Y) binds to the CCAAT box on the ODF promoter and regulates its basal transcriptional activity. The CCAAT box on the ODF gene is required for its transcriptional induction by vitamin D3, suggesting that NF-Y coregulates this promoter along with VDR. Chromatin immunoprecipitation analysis reveals that NF-Y is required for the recruitment of RNA polymerase II (RNAPII) and TATA box binding protein on the ODF promoter. Stimulation with vitamin D3 facilitates the recruitment of VDR and p300 onto the ODF promoter, resulting in acetylation of histone H4 in an NF-Y-independent manner. ODF gene induction by parathyroid hormone or prostaglandin E is also dependent on NF-Y. Furthermore, NF-Y is essential for the recruitment of RNAPII onto other CCAAT box-containing promoters, such as those of osteopontin, CYP24, and E2F1. These results suggest that NF-Y recruits RNAPII and general transcription factors onto various CCAAT box-containing promoters in response to various inductions to permit strong transcriptional activation independently of histone modifications.