PROTEOGLYCAN SYNTHESIS IN HEMATOPOIETIC-CELLS - ISOLATION AND CHARACTERIZATION OF HEPARAN-SULFATE PROTEOGLYCANS EXPRESSED BY THE BONE-MARROW STROMAL CELL-LINE MS-5

Proteoglycans of bone-marrow stromal cells and their extracellular mat rix are important components of the haematopoietic microenvironment. R ecently, several studies have indicated that they are involved in the interaction of haematopoietic stem and stromal cells. However, a detai led characterization of the heparan sulphate proteoglycans synthesized by bone-marrow stromal cells is still lacking. Here we report on the isolation and characterization of proteoglycans from the haematopoieti c stromal cell line MS-5, that efficiently supports the growth and dif ferentiation of human and murine haematopoietic progenitor cells. Bioc hemical characterization of purified proteoglycans revealed that the h aematopoietic stromal cell line MS-5 synthesizes, in addition to chond roitin sulphate proteoglycans, several different heparan sulphate prot eoglycans. Immunochemical analysis, using specific antibodies against the different members of the syndecan family, glypican, betaglycan and perlecan, showed that MS-5 cells synthesize all these different hepar an sulphate proteoglycans. These data were further supported by revers e-transcriptase PCR and confirmed by sequence and Northern blot analys is. The relative abundance of the different heparan sulphate proteogly cans was estimated on the protein and mRNA levels.