CHARACTERIZATION OF NUCLEAR-PROTEIN BINDING-SITES IN THE PROMOTER OF KERATIN K17 GENE

Keratin K17, while not present in healthy skin, is expressed under var ious pathological conditions, including psoriasis and cutaneous allerg ic reactions, The regulatory circuits involved in transcription of the human keratin K17 gene are poorly understood, To begin an analysis of the molecular mechanisms that regulate K17 gene transcription, we hav e studied the interactions between the nuclear proteins and the promot er region of the human K17 gene. That promoter region comprised 450 bp upstream from the translation initiation site, For these studies, we used electrophoretic mobility-shift assays, computer analysis, site-di rected mutagenesis, and DNA-mediated cell transfection, In addition to the previously characterized interferon-gamma-responsive elements, we identified eight protein binding sites in the promoter, Five of them bind the known transcription factors NF1, AP2, and Sp1 and three other s bind still unidentified proteins, Using site-directed mutagenesis, w e have demonstrated the importance of the protein binding sites for th e promoter function involved in both constitutive and interferon-induc ed expression of the K17 keratin gene.