Characterization of proteoglycans synthesized by fetal rat lung type II pneumonocytes in vitro and the effects of cortisol.
The synthesis of proteoglycans by primary cultures of 19-day gestation fetal rat lung Type II pneumonocytes was studied. The cells were grown in the presence of [3H]-glucosamine and/or [35S]-Na2SO4 and the radioactive label incorporated into proteoglycans was analyzed. Proteoglycans of high molecular weight (approximately 200 Kd) were isolated by gel permeation chromatography and contained both [3H] and [35S]. The glycosaminoglycan composition of the proteoglycans was determined by electrophoresis and autoradiography. The medium contained 65-80% of the labeled proteoglycans and was enriched for hyaluronate, with lesser amounts of the sulfated glycosaminoglycans (dermatan sulfate greater than heparan sulfate greater than chondroitin sulfate). The cell layers retained 20-35% of the labeled proteoglycans and was enriched for heparan sulfate, with lesser amounts of chondroitan sulfate greater than dermatan sulfate greater than hyaluronate. The synthesis of proteoglycans was time-dependent and was stimulated by increasing concentrations of fetal bovine serum. Cortisol inhibited proteoglycan synthesis, apparently by decreasing the availability of proteoglycan core-protein.
D000818:Animals; D002478:Cells, Cultured; D006025:Glycosaminoglycans / Q000378:metabolism; D006027:Glycosides / Q000494:pharmacology; D006820:Hyaluronic Acid / Q000096:biosynthesis; D006854:Hydrocortisone / Q000494:pharmacology*; D008168:Lung / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D008970:Molecular Weight; D011509:Proteoglycans / Q000096:biosynthesis*; D051381:Rats
D006025:Glycosaminoglycans; D006027:Glycosides; D011509:Proteoglycans; C010807:xylosides; D006820:Hyaluronic Acid; D006854:Hydrocortisone