EXPRESSION OF DSD-1-PG IN PRIMARY NEURAL AND GLIAL-DERIVED CELL-LINE CULTURES, UP-REGULATION BY TGF-BETA, AND IMPLICATIONS FOR CELL-SUBSTRATE INTERACTIONS OF THE GLIAL-CELL LINE OLI-NEU

DSD-1-PG is a chondroitin sulfate proteoglycan with neurite-outgrowth promoting properties expressed during development and upon lesion of n eural tissues which has been defined with the specific monoclonal anti body 473HD, Double immunofluorescence studies performed on primary cer ebellar cultures document that the proteoglycan is expressed on the su rface of immature glial cells and the neural cell line Oli-neu, a mode l of mouse oligodendrocyte progenitors. Biochemical and immunoprecipit ation studies performed with biosynthetically labelled Oli-neu and pri mary neural cells demonstrated that DSD-1-PG is expressed in vitro as a proteoglycan of 1000 kD apparent Mr with two core glycoproteins of 2 50 kD and 400 kD. In order to study the regulation of DSD-1-PG express ion, an in vitro enzyme-linked immunosorbent assay based on Oli-neu an d mAb 473HD was established. TGF-beta 1-3 induced up-regulation of the proteoglycan, while various growth factors and cytokines did not sign ificantly affect DSD-1-PG expression in both the supernatant and the e xtract of the culture monolayer. FACSCAN analysis suggested that the p roteoglycan is upregulated on the surface of Oli-neu. Cell substrate a dhesion assays revealed that this enhanced expression correlates with a selective reduction of adhesion to laminin, but not fibronectin or m erosin, which could specifically be neutralized by antibodies to DSD-1 -PG. We conclude that the proteoglycan contributes to the regulation o f glial precursor interactions with the extracellular matrix. (C) 1998 Wiley-Liss, Inc.