The Mammalian Hairless Protein as a DNA Binding Phosphoprotein

The study investigated the mammalian hairless (Hr) protein, revealing its specific binding to a p53 response element (p53RE) and its interaction with the p53 protein, which influences the regulation of cell cycle control genes GADD45A and p21. Chromatin immunoprecipitation (ChIP) assays confirmed HR binding to the p53RE of the GADD45A gene in HEK293 and U87 cells. Co-immunoprecipitation assays showed direct interaction between HR and p53. Additionally, Hr was found to be a substrate for PKC but not PKA, with human HR phosphorylated at Ser-416 in U87 cells. These findings suggested that Hr is a phosphoprotein involved in the p53 pathway, impacting cell proliferation and differentiation in skin and brain tissues.