Connective tissue activation: stimulation of glucose transport by connective tissue activating peptide III

Abstract

Connective tissue activating peptide III (CTAP III), a human platelet derived growth factor, induced marked stimulation of 2-deoxy[14C]glucose (2dG) uptake in cultures of human synovial cells, chondrocytes, and dermal fibroblasts. Cytochalasin B (2 X 10(-5) M) blocked the mediator-induced increase in 2dG uptake; phlorhizin (8 X 10(-4) M) partially inhibited this process. When cells were exposed to CTAP III (4 X 10(-6) M) for 30 min prior to uptake assay, 2dG uptake was stimulated by 30-110%; greater stimulation (400-800%) occurred following 17-40-h preincubation with the mediator. A 17-h exposure to CTAP III similarly stimulated 3-O-methylglucose uptake by over 400%, suggesting that CTAP III stimulated 2dG uptake is mediated via changes in hexose transport. Cycloheximide clearly prevented the 17-h effects of CTAP III on 2dG uptake. Insulin (3 X 10(-6) M) stimulated 2dG uptake 40-70% after 30-min preincubation with hormone; little effect was seen after 17-h preincubation. These data suggest that CTAP III stimulates glucose transport shortly after addition to target cells; the major stimulation observed after a 17-h incubation is consistent with the synthesis of new glucose transport protein.