STRUCTURAL ORGANIZATION AND PROMOTER ACTIVITY OF THE HUMAN RYUDOCAN GENE

To better understand the regulation of ryudocan (syndecan-4) expressio n, we have determined the structural organization of the human ryudoca n gene. The human ryudocan gene extends approximately 24 kilobases and is divided into five exons, which appear to be conserved in syndecan family members. Exon I encodes the signal peptide; exons II-IV, the ex tracellular domain; and exon V, the transmembrane and cytoplasmic doma ins, which are highly homologous among syndecan family members. Primer extension analysis showed that human ryudocan gene had a single trans cription initiation site, located 3 bases upstream from the described cDNA [Kojima et al. (1993) BBRC 190, 814-822], The 5'-flanking sequenc es of human ryudocan gene contain a TATA-like sequence as well as a va riety of other potential binding sites for transcription factors, incl uding Sp1, Ap-2, NF-kB, E-alpha H box, H4TF-2, and LBP-1, and were cap able of functioning as a promoter. The determination of the human ryud ocan gene structure will allow elucidation of constitutive, cell-speci fic, tissue-specific, and developmentally regulated expression.