Regulation of TAK1/TAB1-mediated IL-1? signaling by cytoplasmic PPAR?/?.

ABSTRACT: The peroxisome proliferator-activated receptor subtypes PPAR?, PPAR?/?, PPAR? are members of the steroid hormone receptor superfamily with well-established functions in transcriptional regulation. Here, we describe an unexpected cytoplasmic function of PPAR?/?. Silencing of PPAR?/? expression interferes with the expression of a large subset of interleukin-1? (IL-1?)-induced target genes in HeLa cells, which is preceded by an inhibition of the IL-1?-induced phosphorylation of TAK1 and its downstream effectors, including the NF?B? inhibitor I?B? (NFKBIA) and the NF?B? subunit p65 (RELA). PPAR?/? enhances the interaction between TAK1 and the small heat-shock protein HSP27, a known positive modulator of TAK1-mediated IL-1? signaling. Consistent with these findings, PPAR?/? physically interacts with both the endogenous cytoplasmic TAK1/TAB1 complex and HSP27, and PPAR?/? overexpression increases the TAK1-induced transcriptional activity of NF?B. These observations suggest that PPAR?/? plays a role in the assembly of a cytoplasmic multi-protein complex containing TAK1, TAB1, HSP27 and PPAR?/?, and thereby participates in the NF?B response to IL-1?.

SUBMITTER: Stockert J 

PROVIDER: S-EPMC3639976 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature