ABSTRACT
Myeloid differentiation factor MyD88 is a critical adaptor molecule that integrates and transduces intracellular signals in inducing the differentiation of dendritic cells (DCs).The domain regions within MyD88 was searched,it could potentially affect the function of dendritic cells and found that MyD88 aa155-171 motif not only regulate the activity of transcription factor NF-?B, but also control the production of cytokines and expression of costimulatory molecules. Indeed, aa155-171 motif deleted type MyD88 (MyD88155-171) transfected RAW264.7 cells exhibited the reduced NF-?B and AP-1 activity and interrupted the expression of CD86 and B7H1. Meanwhile, lower level expression of cytokines such as IL-12,IFN-? were also observed by means of cytokine array in MyD88-/-DC trasfected with MyD88155-171 as compared to the MyD88 transfected cells. Thus, aa155-171 motif inside MyD88 could affect the expression of costimulatory molecules, production of cytokines and transduction of Toll like receptor signal pathway, suggesting that this motif may play an important role in regulating responses of innate immune system.