RESUMEN
Tumour necrosis factor (TNF) is produced by primary human macrophages in response to stimulation by exogenous pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs) via Toll-like receptor (TLR) signalling. However, uncontrolled TNF production can be deleterious and hence it is tightly controlled at multiple stages. We have previously shown that Bruton's tyrosine kinase (Btk) regulates TLR4-induced TNF production via p38 MAP Kinase by stabilising TNF messenger RNA. Using both gene over-expression and siRNA-mediated knockdown we have examined the role of Btk in TLR7/8 mediated TNF production. Our data shows that Btk acts in the TLR7/8 pathway and mediates Ser-536 phosphorylation of p65 RelA and subsequent nuclear entry in primary human macrophages. These data show an important role for Btk in TLR7/8 mediated TNF production and reveal distinct differences for Btk in TLR4 versus TLR7/8 signalling.
Asunto(s)
FN-kappa B/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Receptor Toll-Like 7/metabolismo , Receptor Toll-Like 8/metabolismo , Transcripción Genética , Factor de Necrosis Tumoral alfa/genética , Regiones no Traducidas 3'/genética , Agammaglobulinemia Tirosina Quinasa , Emparejamiento Base/genética , Núcleo Celular/metabolismo , Citocinas/biosíntesis , Regulación hacia Abajo/genética , Humanos , Fosforilación , Regiones Promotoras Genéticas/genética , Receptor Toll-Like 4/metabolismo , Factor de Transcripción ReIA/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
The activity of tyrosine kinases is central to many cellular processes, and accumulating evidence suggests that their role in inflammation is no less profound. Three main tyrosine kinase families, the Src, Tec and Syk kinase families are intimately involved in TLR signalling, the critical first step in cellular recognition of invading pathogens and tissue damage. Their activity results in changes in gene expression in affected cells. Key amongst these genes are the cytokines, which orchestrate both the duration and extent of inflammation. Tyrosine kinases also play important roles in cytokine function, and are implicated in signalling through both pro- and anti-inflammatory cytokines such as TNF, IL-6 and IL-10. Thus, strategies to modulate tyrosine kinase activity have significant therapeutic potential in combating the chronic inflammatory state that is typical of many major health issues that face us today, including Rheumatoid Arthritis, Cardiovascular disease and cancer. Here we review current knowledge of the role of tyrosine kinases in inflammation with particular emphasis on their role in TLR signalling.