Negative regulation of transforming growth factor-β by the proteoglycan decorin

DECORIN is a small chondroitin–dermatan sulphate proteoglycan consisting of a core protein and a single glycosaminoglycan chain1–3. Eighty per cent of the core protein consists of 10 repeats of a leucine-rich sequence of 24 amino acids2,4. Similar repeats have been found in two other proteoglycans, biglycan5 and fibromodulin6, and in several other proteins including Drosophila morphogenetic proteins7–11. Expression of high levels of decorin in Chinese hamster ovary cells has a dramatic effect on their morphology and growth properties1. We now report that this effect is due at least in part to the ability of decorin to bind transforming growth factor-β, an autocrine factor12,13 that stimulates the growth of Chinese hamster ovary cells. As transforming growth factor-β induces synthesis of decorin in many cell types14,15, our results suggest that decorin may be a component of a feedback system regulating cell growth.