DIFFERENTIAL EXPRESSION OF MULTIPLE CELL-SURFACE HEPARAN-SULFATE PROTEOGLYCANS DURING EMBRYONIC TOOTH DEVELOPMENT

Heparan sulfate accumulates on cell surfaces and at cell-matrix interf aces, and functionally modulates several of the effector molecules tha t support the interactions, growth, and differentiation of developing tissues. Using heparan sulfate-specific monoclonal antibodies MAb, we obtained evidence that extracts from rodent embryos contain multiple f orms of cell surface-associated heparan sulfate proteoglycan (PG). Tak ing tooth development in the mouse embryo as a model to further invest igate the relevance of this PG redundancy and using MAb against hepara n sulfate, antibodies specific for syndecan (syndecan-1) and fibroglyc an (syndecan-2) (two distinct members of a larger family of cell-surfa ce heparan sulfate PGs), and specific cDNA probes for these two cell-s urface PGs, we obtained in situ evidence for regulated and differentia l expression of multiple cell-surface heparan sulfate PGs. The unique, distinctive, and coordinated changes in the expressions of these PGs during morphogenesis and differentiation of dental tissues suggest tha t the various cell-surface PGs are not truly redundant but play import ant, specific, and potentially complementary roles during embryonic de velopment.