MAPKAP Kinase 2 Blocks Tristetraprolin-directed mRNA Decay by Inhibiting CAF1 Deadenylase Recruitment

• Published in: The Journal of biological chemistry 2010-09, Vol.285 (36), p.27590-27600
• Main Authors: Marchese, Francesco P., Aubareda, Anna, Tudor, Corina, Saklatvala, Jeremy, Clark, Andrew R., Dean, Jonathan L.E.
• Format: Article
• Language: English
• Subjects: 14-3-3 protein; 14-3-3 Proteins - metabolism; Animals; Base Composition; Carbon; Cyclooxygenase 2 - genetics; Cyclooxygenase-2; Deadenylation; Gene Regulation; HeLa Cells; Humans; Inflammation; Intracellular Signaling Peptides and Proteins - metabolism; MAP kinase; MAP Kinase Signaling System; MAPKAP kinase 2; MAPKAPK-2; Mice; mRNA stability; p38 MAPK; p38 Mitogen-Activated Protein Kinases - metabolism; Phosphorylation; Post-transcriptional Regulation; Protein kinase; Protein-Serine-Threonine Kinases - metabolism; Receptors, CCR4 - metabolism; Repressors; Ribonucleases - metabolism; RNA Binding Protein; RNA Stability; RNA Turnover; RNA, Messenger - chemistry; RNA, Messenger - metabolism; Signal Transduction; Transcription Factors - metabolism; Tristetraprolin; Tristetraprolin - metabolism; Tumor Necrosis Factor-alpha - genetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.136473

Tristetraprolin (TTP) directs its target AU-rich element (ARE)-containing mRNAs for degradation by promoting removal of the poly(A) tail. The p38 MAPK pathway regulates mRNA stability via the downstream kinase MAPK-activated protein kinase 2 (MAPKAP kinase 2 or MK2), which phosphorylates and prevents the mRNA-destabilizing function of TTP. We show that deadenylation of endogenous ARE-containing tumor necrosis factor mRNA is inhibited by p38 MAPK. To investigate whether phosphorylation of TTP by MK2 regulates TTP-directed deadenylation of ARE-containing mRNAs, we used a cell-free assay that reconstitutes the mechanism in vitro. We find that phosphorylation of Ser-52 and Ser-178 of TTP by MK2 results in inhibition of TTP-directed deadenylation of ARE-containing RNA. The use of 14-3-3 protein antagonists showed that regulation of TTP-directed deadenylation by MK2 is independent of 14-3-3 binding to TTP. To investigate the mechanism whereby TTP promotes deadenylation, it was necessary to identify the deadenylases involved. The carbon catabolite repressor protein (CCR)4·CCR4-associated factor (CAF)1 complex was identified as the major source of deadenylase activity in HeLa cells responsible for TTP-directed deadenylation. CAF1a and CAF1b were found to interact with TTP in an RNA-independent fashion. We find that MK2 phosphorylation reduces the ability of TTP to promote deadenylation by inhibiting the recruitment of CAF1 deadenylase in a mechanism that does not involve sequestration of TTP by 14-3-3. Cyclooxygenase-2 mRNA stability is increased in CAF1-depleted cells in which it is no longer p38 MAPK/MK2-regulated.