Abstract
Transforming growth factor-beta (TGF-beta) family members are multifunctional growth factors involved in regulating diverse biological processes. Despite the critical role for TGF-beta in regulating cell proliferation, differentiation, migration and development, its role in regulating NF-kappaB-dependent inflammatory response still remains unclear. Here, we show that TGF-beta1 induces acetylation of NF-kappaB p65 subunit to synergistically enhance bacterium nontypeable Haemophilus influenzae-induced NF-kappaB activation and inflammatory response in vitro and in vivo. The TGF-beta1-induced acetylation of p65 is mediated via a Smad3/4-PKA-p300-dependent signaling pathway. Acetylation of p65 at lysine 221 by TGF-beta1 is critical for synergistic enhancement of bacteria-induced DNA-binding activity, NF-kappaB activation, NF-kappaB-dependent transcription of TNF-alpha and IL-1beta and interstitial polymorphonuclear neutrophil infiltration in vitro and in vivo. These studies provide new insights into the novel regulation of NF-kappaB by TGF-beta signaling.