AJP - Lung Cellular and Molecular Physiology, Vol 266, Issue 6 672-L680, Copyright © 1994 by American Physiological Society
Transforming growth factor-beta induces a chondroitin sulfate/dermatan sulfate proteoglycan in alveolar type II cells
W. M. Maniscalco and M. H. Campbell
Department of Pediatrics, Strong Children's Research Center, University of Rochester, New York 14642.
Alveolar type II cells can synthesize extracellular matrix (ECM) components
in vitro, including proteoglycans. Transforming growth factor-beta
(TGF-beta) profoundly influences ECM production and is found in areas of
lung fibrosis. To determine whether type II cell proteoglycan synthesis is
regulated by TGF-beta, we cultured adult rabbit type II cells with TGF-beta
1 and analyzed the synthesis of proteoglycans secreted into the culture
medium. TGF-beta 1 increased 35SO4 incorporation into glycosaminoglycans of
secreted proteoglycans 2.5-fold. Analysis of the intact proteoglycans
revealed that TGF-beta 1 induced accumulation of a chondroitin
sulfate/dermatan sulfate proteoglycan with molecular mass between 70 and
100 kDa and a core protein of 36 kDa. There were no effects on several
other core proteins. Type II cells cultured with TGF-beta 1 and
beta-D-xyloside, an acceptor for glycosaminoglycan polymerization, had
increased glycosaminoglycan synthesis independent of the availability of
core proteins. These data indicate that type II cell proteoglycan
synthesis, at the levels of both core protein and glycosaminoglycans, is
regulated by TGF-beta 1. We speculate that the induced 70- to 100 kDa
proteoglycan is decorin, an ECM proteoglycan involved in collagen
fibrillogenesis and TGF-beta binding.
