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The p38 mitogen-activated protein kinase (MAPK) signaling pathway, acting through the downstream kinase MK2, regulates the stability of many proinflammatory mRNAs that contain adenosine/uridine-rich elements (AREs). It is thought to do this by modulating the expression or activity of ARE-binding proteins that regulate mRNA turnover. MK2 phosphorylates the ARE-binding and mRNA-destabilizing protein tristetraprolin (TTP) at serines 52 and 178. Here we show that the p38 MAPK pathway regulates the subcellular localization and stability of TTP protein. A p38 MAPK inhibitor causes rapid dephosphorylation of TTP, relocalization from the cytoplasm to the nucleus, and degradation by the 20S/26S proteasome. Hence, continuous activity of the p38 MAPK pathway is required to maintain the phosphorylation status, cytoplasmic localization, and stability of TTP protein. The regulation of both subcellular localization and protein stability is dependent on MK2 and on the integrity of serines 52 and 178. Furthermore, the extracellular signal-regulated kinase (ERK) pathway synergizes with the p38 MAPK pathway to regulate both stability and localization of TTP. This effect is independent of kinases that are known to be synergistically activated by ERK and p38 MAPK. We present a model for the actions of TTP and the p38 MAPK pathway during distinct phases of the inflammatory response.

Original publication

DOI

10.1128/MCB.26.6.2408-2418.2006

Type

Journal

Mol Cell Biol

Publication Date

03/2006

Volume

26

Pages

2408 - 2418

Keywords

Animals, Cell Nucleus, Cells, Cultured, Cytoplasm, Enzyme Inhibitors, Extracellular Signal-Regulated MAP Kinases, Humans, Lipopolysaccharides, Mice, Phosphoprotein Phosphatases, Phosphorylation, Proteasome Endopeptidase Complex, Protein Processing, Post-Translational, Serine, Signal Transduction, Tristetraprolin, p38 Mitogen-Activated Protein Kinases