Role of protein tyrosine kinase in activation of MAPKs induced by TNF α in fibroblast like synoviocytes of rheumatoid arthritis
Objective To study on MAPKs (mitogen activated protein kinases) activation in rheumatoid arthritis fibroblast like synoviocytes (RA FLS) under the stimulation of TNF α, and to elucidate the role of protein tyrosine kinase (PTK) in activation of MAPKs. Methods RA FLS were primarily cultured. Western blots were applied to examine transient change of protein tyrosine phosphorylation status and MAPKs activation in RA FLS stimulated with various doses and periods of TNF α. Genistein, the specific PTK inhibitor was used to evaluate the inhibitory role in activation of MAPKs by TNF α. Results TNF α transiently increased protein tyrosine phosphorylation, and activated MAPKs cascades (mainly ERK2, JNK2, P38) in RA FLS. The peak activation of ERK2 and JNK2 were obtained at 10IU/ml, but that of P38 was at 100IU/ml. The maximal activation of ERK2, JNK2 and P38 was observed at 5, 15 and 15 minutes respectively after stimulation with TNF α. The activation of ERK2 was strongly inhibited by genistein, but the inhibitory role on that of JNK and P38 was relatively weak. Conclusion During signal transduction of TNF α in RA FLS, tyrosine phosphorylation were increased transiently, MAPKs cascades were activated in a few minutes, PTK plays a significant role in the activation of ERK, but has only weak effect on that of JNK and P38.