MOLECULAR-CLONING, GENOMIC ORGANIZATION, PROMOTER ACTIVITY, AND TISSUE-SPECIFIC EXPRESSION OF THE MOUSE RYUDOCAN GENE

Ryudocan, a ubiquitous heparan sulfate proteoglycan, is a member of th e syndecan family of cell surface proteoglycans. The full-length cDNA encoding the murine ryudocan core protein has now been cloned and sequ enced. The deduced primary structure of mouse ryudocan, including the three glycosaminoglycan attachment sites in the extracellular domain a s well as the transmembrane and cytoplasmic regions, is highly similar to those of the rat, human, and chicken proteins. Northern analysis d etected a 2.7-kb transcript in all mouse tissues examined, with the hi ghest concentrations apparent in liver, kidney, and lung. The mouse ry udocan gene was shown to span approximately 19.7 kb of genomic DNA and to contain five exons, with an intron-exon organization identical to that of the human gene. The promoter region of the mouse gene contains various cis-acting elements, including a TATA-like box and a GC box a s well as potential binding sites for the transcription factors NF-IL6 , MyoD, GATA, C/EBP, AP-2, NF-kappa B, AP-I, and Spl. Transient transf ection experiments with a construct containing the 690 bp upstream of the transcription start site fused to a luciferase reporter gene showe d functional promoter activity. Deletion analysis suggested that the p roximal promoter region including the TATA-like box, the GC box, and o ther Spl binding sites was required for full transcriptional activity. These findings will be useful for the study of ryudocan gene regulati on and the generation of mice with targeted disruption of the gene.