Platelet-derived growth factor induces interleukin-1 receptor gene expression in Balb/c 3T3 fibroblasts

Our previous studies have demonstrated that platelet-derived growth factor (PDGF) modulated cellular responses to interleukin-1 (IL-1). In this communication, we show that PDGF regulates expression of IL-1 receptor (IL-1 R) gene. Treatment of quiescent cultures of Balb/c 3T3 fibroblasts with PDGF produced 20-30-fold stimulation of IL-1 R mRNA with a concomitant increase in cell surface 125I-binding. IL-1 R mRNA accumulation occurred after an initial lag period and with a time course preceding the increase in 125I-IL-1 binding to cells. Induction of IL-1 R mRNA was blocked by inhibitors of protein synthesis, suggesting that a product of a gene expressed immediately after PDGF addition is required for IL-1 R gene expression. These latter data provide evidence for an ordered sequence of expression of PDGF-inducible "immediate early" gene(s) and IL-1 R gene. These results suggest that in connective tissues, PDGF may be an important determinant in initiating and maintaining cellular responses to IL-1. Such responses may have important consequences in the actions of IL-1 under normal and pathological conditions such as arthritis and atherosclerosis.