The regulatory region of the human desmocollin 3 promoter forms a DNA four-way junction

Adhesion between desmosomal junctions is mediated by structural proteins of the cadherin family, viz. three desmocollins (DSC) and three desmogleins ( DSG). Promoter and primer extension analysis of human DSC3 showed a TATA-le ss sequence initiating transcription via a cluster of sites upstream of the coding region. Deletion analysis of 1 kb of the promoter showed that expre ssion is regulated between -303 and -203 bp upstream of the start-site of t ranslation. Tertiary structure analysis of this cis-active region (cis 1) r evealed a potential DNA 4-way junction which is notably G/C-rich in sequenc e. PAGE analysis of this region identified four differently migrating forms of the DNA. Structure-specific cleavage of the DNA with bacteriophage T7 e ndonuclease I showed the slowest migrating form to be either an extended/cr uciform or stacked-X 4-way junction. DNA-binding, gel retardation assays of the cia 1 region showed distinct DNA-protein complexes and by competition experiments and using purified junction DNA we show that one of these compl exes bound with both sequence and structure specificity to the 4-way juncti on DNA. (C) 2001 Academic Press.