Figure 6.

A: Three-day-old cultures of Hurler fibroblasts demonstrate higher levels of secreted and unassembled, and cell- and matrix-associated fibronectin, as compared with normal and Sanfilippo fibroblasts. Incubation of Hurler fibroblasts in the presence of 0.2 U/day of chondroitinase ABC (Chnase ABC) causes reduction of their fibronectin levels. B: Addition of DS, but not HS (both in concentrations of 400 μg/ml), significantly increased net production of fibronectin in 48-hour cultures of normal fibroblasts. Production of fibronectin was assessed by incorporation of ³⁵S-methionine into the 220-kd protein isolated by gelatin-sepharose affinity and identified as fibronectin by immunoblotting. Results from normal, Sanfilippo, and Hurler fibroblasts treated with different additions were statistically compared with respective untreated controls. Values of mean ± SD from three different experiments were statistically compared (*P < 0.001). C: Northern blot analysis of confluent normal fibroblasts cultures incubated for 24 hours in the presence or absence of 400 μmol/L DS or HS. Levels of fibronectin mRNA detected in cultures treated with both glycosaminoglycans did not differ from levels observed in untreated control culture. Levels of ethidium bromide-stained 28S and 18S ribosomal RNA indicate equal sample loading.