Analysis of amino acid residues affecting the transcriptional activity of nuclear factor Ya.

Nuclear factor Y (NF-Y) is a heterotrimeric transcription factor essential for regulating genes involved in lipid metabolism, including fatty acid synthase (Fasn). Although NF-Y activity is known to be dynamically regulated during adipocyte differentiation, the amino acid residues responsible for its transcriptional function remain unclear. In this study, we examined the contribution of nuclear factor Ya (NF-Ya) to DNA-binding activity and transcriptional regulation in 3T3-L1 adipocytes. Using deletion constructs and adenoviral expression systems, we identified a region spanning amino acid residues 184-347 of NF-Ya as critical for acquiring DNA-binding ability during differentiation. Electrophoretic mobility shift assays revealed that NF-Ya undergoes modification within this region, conferring stage-specific DNA-binding activity to the Fasn promoter. These findings suggest that post-translational modification of NF-Ya is a key mechanism regulating NF-Y function in adipogenesis. Our work provides novel insights into transcriptional control of lipogenic genes and their relevance to metabolic regulation.