THE MURINE DECORIN - COMPLETE CDNA CLONING, GENOMIC ORGANIZATION, CHROMOSOMAL ASSIGNMENT, AND EXPRESSION DURING ORGANOGENESIS AND TISSUE DIFFERENTIATION

Decorin, a proteoglycan known to interact with collagen and growth fac tors, may play key roles during ontogenesis, tissue remodeling, and ca ncer. We have deciphered the complete protein sequence of the murine d ecorin by cDNA cloning, elucidated its gene structure and chromosomal location, and investigated its expression in the developing embryo. Th e decorin protein and the gene were highly conserved vis a vis the hum an counterpart; however, the murine gene lacked a leader exon, exon Ib , which was found only in the human. Using interspecific backcrossing, we assigned the gene to chromosome 10 just proximally to the Steel ge ne locus. In situ hybridization studies of developing mouse embryos sh owed a distinct pattern of expression with a progressive increase of d ecorin mRNA during ontogenesis. At early stages (day 11 postconception ), decorin was detectable only in the floor plate region. Subsequently (days 13-16 postconception), decorin expression was especially promin ent in the meninges and mesothelial linings of pericardium, pleura, an d coelomic cavity, as well as in the dermis and subepithelial layers o f the intestine and urinary bladder. In contrast, the major parenchyma l organs were only weakly positive for decorin mRNA. These findings su ggest that decorin may play a role in epithelial/mesenchymal interacti ons during organ development and shaping.