Expression of N-deacetylase/sulfotransferase and 3-O-sulfotransferase in rat alveolar type II cells

Basal laminae beneath alveolar type I cells are suggested to contain highly sulfated heparan sulfate-containing proteoglycans (PGs), and cultured type II cells accumulate highly sulfated matrices. To characterize the regulati on of PG synthesis during the transition from type II cells to type I cells , we examined mRNA expression of N-deacetylase/sulfotransferase (NST) and 3 -O-sulfotransferase (3-OST), two enzymes specific for heparan sulfate synth esis. We found that both freshly isolated and cultured type II cells expres sed NST and 3-OST as shown by in situ hybridization. Expression of surfacta nt-associated protein A, B, and C mRNAs, determined by semiquantitative PCR , decreased during culture. Expression of type I cell marker T1 alpha mRNA increased except in cells cultured on an Engelbrecht-Holm-Swarm gel. Expres sion of NST was dependent on cell density and matrix and was intense in con ditions where cells spread fully, whereas 3-OST expression was unchanged in the conditions examined. The PG sulfation inhibitor sodium chlorate signif icantly inhibited cultured type II cell spreading, and this inhibition was reversed by sodium sulfate. These results suggest that highly sulfated PGs modified by NST are necessary for the spreading of cells during transdiffer entiation of type II cells to mature type I cells.