DEVELOPMENTAL EXPRESSION OF THE SYNDECANS - POSSIBLE FUNCTION AND REGULATION

Recent work has made clear that heparan sulfate at the cell surface is essential for a wide variety of interactions of cells with their micr oenvironment, including the action of growth factors, extracellular ma trix, proteases and protease inhibitors. A major source of this cell s urface heparan sulfate is a multigene family of proteoglycans, the syn decans, that are expressed developmentally in association with changes in tissue organization and morphology and induced during wound repair . In this review, we describe mechanisms underlying the differential e xpression of the syndecans, focusing on syndecan-1. The induction of s yndecan-1 can result from soluble extracellular factor(s) acting at mu ltiple levels of cellular regulation. At the transcriptional level, th e promoter of the murine syndecan-1 gene contains potential recognitio n sites for several well-known regulatory genes, including Hox and Myo D family members. Because changes in syndecan expression enable cells to become more or less responsive to their microenvironment, understan ding these regulatory mechanisms can lead to an improved understanding of how cellular behavior is controlled during development and wound r epair.