Differentiation and de-differentiation of cultured chondrocytes: increase in monomeric size of 'cartilage-specific' proteoglycans by dibutyryl cyclic AMP and complete inhibition of their synthesis by retinoic acid.

Abstract

Dibutyryl cyclic AMP (DBcAMP) induced an increase in the monomeric size of 'cartilage-specific' proteoglycans (PG-I) in rabbit costal chondrocytes in culture. This increase in size was due to an increase in the average molecular weight of the glycosaminoglycan (GAG) chains. In contrast, retinoic acid completely inhibited the synthesis of PG-I. However, the synthesis and monomeric size of 'ubiquitous' proteoglycans (PG-II) were little affected by these agents. These results suggested that modulation of the differentiated state of chondrocytes is closely related to not only the synthesis of 'cartilage-specific' proteoglycans but also their monomeric size.