Biosynthesis of hyaluronic acid, heparan sulfate and structural glycoproteins in hamster lung explants during elastase induced emphysema

Abstract

Hyaluronic acid (HA), heparan sulfate (HS) and structural glycoproteins (SGP) were investigated in explant cultures of hamster lungs by studying incorporation of 14C-glucosamine (14C GlcN) on the first and on the 24th day after intratracheal administration of pancreatic elastase. The different 14C radiolabeled macromolecules were extracted sequentially by 0.4 M guanidinium chloride (0.4 M GUA), 4 M GUA and collagenase digestion. At one day following elastase injury, a 4.2 fold increase of 14C GlcN incorporation into HA released in 0.4 M GUA extract and a 2.6 fold increase into HS released in the collagenase digests were observed compared to control tissues; at 24 days, the increased 14C GlcN incorporation into HA and HS persist but to a lesser extent. Polyacrylamide gel electrophoresis and isoelectric focusing carried out on 4 M GUA extracts, demonstrated identical quantitative and qualitative distribution of 14C GlcN between the major SGP (140 and 110 K with pI 7.8 and 4.5 respectively) in the normal and the experimental groups. These results indicate that pulmonary SGP biosynthesis is not modified at one and 24 days after elastase injury, whereas HA and HS biosynthesis are consistently increased. These results suggest a specific role of these macromolecules in emphysematous injury of the lung.