Control of mRNA decay by phosphorylation of tristetraprolin

TTP (tristetraprolin) is an RNA-binding protein that suppresses inflammation by accelerating the degradation of cytokine mRNAs. TTP binds to an AU-rich element in the T-untranslated region of its target mRNAs. In macrophages, the induction of cytokine expression requires activation of the p38-MAPK (mitogen-activated protein kinase)-MK2 [MAPKAP (MAPK-activated protein) kinase-2] kinase cascade. MK2 directly phosphorylates TTP and thereby contributes to transient stabilization of cytokine mRNAs. In the present review, we address the target specificity of TTP, summarize UP-interacting proteins and discuss how phosphorylation regulates the activity, localization and stability of TTP.