Effects of Human Carbonic Anhydrase III (CA III) on Synovial and Muscle Fibroblast Glycosaminoglycan Metabolism

We investigated the ability of CA III, isolated from adult human skeletal muscle, to regulate cell growth and glycosaminoglycan (GAG) formation in connective tissue cells derived from various human tissues. Unlike muscle, dermal, and cartilage fibroblasts, synovial connective tissue cells were substantially activated by CA III and showed enhanced hyaluronic acid (HA) synthesis. Cell culture experiments showed that CA III induced a 2- to 11-fold increase in [14C]HA synthesis by human synovial fibroblasts (SF) in a dose-dependent manner (P less than 0.001); erythrocyte CA I and CA II were inactive. Exposure of SF and muscle fibroblasts to CA III also resulted in a 20-45% and 16-70% increased 35S incorporation into proteoglycans, respectively. When adult human skin and cartilage fibroblasts were studied in the presence of CA III, no differences in the level of DNA and GAG formation were noted. These latter cell types were clearly activated by a platelet (CTAP-III) growth factor. The potential physiological implications of these observations are discussed.