Interleukin 1 and tumour necrosis factor increase phosphorylation of fibroblast proteins

Interleukin 1 (IL1) or tumour necrosis factor (TNF) stimulated phosphorylation of a triad of 27 kDa phosphoproteins (pI 6.0, 5.7 and 5.5) in human dermal fibroblasts. The change was dependent on the dose of cytokine in the range 0.1-20 ng, was detectable between 3 and 5 min after stimulation and was maximal by 10 min. The proteins were found in the cytosol after subcellular fractionation. The 32P was removed from them by alkali, indicating the presence of phosphoserine and/or phosphothreonine. The results suggest that early changes in serine/threonine protein kinase activity may be involved in responses of fibroblasts to IL1 and TNF.