Control of LPS-response by DUSP1

Activation of the Mitogen activated protein kinase (MAPK) cascade following Toll-like receptor (TLR) stimulation enables innate immune cells to rapidly activate cytokine gene expression. A balanced response to signals of infectious danger requires that cellular activation is transient. Here, we identify the MAPK phosphatase Dual specificity phosphatase-1 (DUSP1) as an essential endogenous regulator of the inflammatory response to LPS. DUSP1-deficient (DUSP1-/-) bone marrow derived macrophages showed selectively prolonged activation of p38 MAPK and increased cytokine production. Intraperitoneal challenge of DUSP1-/- mice with LPS caused increased lethality and overshooting production of IL-6 and TNF?. Transcriptional profiling revealed that DUSP1 controls a significant fraction of LPS-induced genes, that includes IL-6 and IL-10 as well as the chemokines CCL3, CCL4 and CXCL2. In contrast, the expression of the important mediators of endotoxin lethality, IFN? and IL-12, was not significantly altered by the absence of DUSP1. These data together demonstrate a specific regulatory role of DUSP1 in controlling a subset of LPS-induced genes that determines the outcome of endotoxin shock. Keywords: in vivo analysis of splenic mRNA expression Mice were injected intraperitoneally with E. coli LPS (10µg/g bodyweight) and sacrificed 6h later. Total spleen RNA (5 µg) was prepared, labeled and hybridized to Affymetrix MOE430A 2.0 GeneChips according to the manufacturer’s instructions. Three biological replicates per condition were analysed. CEL Files were processed for global normalization and generation of expression values using the rma algorithm in the R affy package (www.bioconductor.org).