Biosynthesis of sulfated extracellular matrices by alveolar type II cells increases with time in culture
Sannes, P.L.; Khosla, J.; Peters, B.P.
American Journal of Physiology 273(4): L840-L847
1997
ISSN/ISBN: 0002-9513 PMID: 9357860 Document Number: 481326
The aim of this study was to determine the extent to which sulfate incorporated into biosynthesized basement membrane (BM) components increased as isolated type II cells progress toward a more type I cell-like phenotype from 7 to 21 days in culture. Specific sulfate cytochemistry, using high iron diamine, showed that type I-like cells in 21-day cultures deposited a more highly sulfated extracellular matrix. Biosynthetic labeling experiments using (35S)cysteine or (35S)sulfate as precursors confirmed the increased capacity of 21-day type I-like cells to biosynthesize sulfated BM components compared with type II-like cells in 7-day cultures, including a novel sulfated laminin. These biochemical changes in sulfation of BM components coincide with the established phenotypic transition from type II to type I cells during prolonged culture. More importantly, the data suggest that regulation of sulfation constitutes a potential mechanism by which type I and type II cells alter their environment in such a manner as to stabilize phenotype and modulate responses to growth factors.