Global dissociation of HuR-mRNA complexes promotes cell survival after ionizing radiation

• Published in: The EMBO journal Vol. 30; no. 6; pp. 1040 - 1053
• Main Authors: Masuda, Kiyoshi, Abdelmohsen, Kotb, Kim, Mihee M, Srikantan, Subramanya, Lee, Eun Kyung, Tominaga, Kumiko, Selimyan, Roza, Martindale, Jennifer L, Yang, Xiaoling, Lehrmann, Elin, Zhang, Yongqing, Becker, Kevin G, Wang, Jian-Ying, Kim, Hyeon Ho, Gorospe, Myriam
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 16.03.2011; Nature Publishing Group UK; Blackwell Publishing Ltd; Nature Publishing Group
• Subjects: Antigens, Surface - genetics; Antigens, Surface - metabolism; Cell Line; Cell Survival; Checkpoint Kinase 2; Chk2; Colorectal carcinoma; ELAV Proteins; ELAV-Like Protein 1; EMBO13; EMBO36; Epithelial Cells - radiation effects; Gene expression; Gene Expression Regulation; Gene Knockout Techniques; Humans; HuR phosphorylation; Ionizing radiation; Molecular biology; Mutants; Phosphorylation; Protein-Serine-Threonine Kinases - metabolism; Radiation; Radiation, Ionizing; radiotherapy; ribonucleoprotein complex; RNA, Messenger - metabolism; RNA-binding protein; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; RNA-protein interactions; Survival; radiotherapy; HuR phosphorylation; ribonucleoprotein complex; Chk2; RNA‐binding protein
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/emboj.2011.24

Ionizing radiation (IR) triggers adaptive changes in gene expression. Here, we show that survival after IR strongly depends on the checkpoint kinase Chk2 acting upon its substrate HuR, an RNA‐binding protein that stabilizes and/or modulates the translation of target mRNAs. Microarray analysis showed that in human HCT116 colorectal carcinoma cells (WT), IR‐activated Chk2 triggered the dissociation of virtually all of HuR‐bound mRNAs, since IR did not dissociate HuR target mRNAs in Chk2‐null (CHK2−/−) HCT116 cells. Accordingly, several HuR‐interacting mRNAs encoding apoptosis‐ and proliferation‐related proteins (TJP1, Mdm2, TP53BP2, Bax, K‐Ras) dissociated from HuR in WT cells, but remained bound and showed altered post‐transcriptional regulation in CHK2−/− cells. Use of HuR mutants that were not phosphorylatable by Chk2 (HuR(3A)) and HuR mutants mimicking constitutive phosphorylation by Chk2 (HuR(3D)) revealed that dissociation of HuR target transcripts enhanced cell survival. We propose that the release of HuR‐bound mRNAs via an IR‐Chk2‐HuR regulatory axis improves cell outcome following IR. The RNA‐binding protein HuR is phosphorylated by the checkpoint kinase Chk2. Here, Chk2‐mediated HuR phosphorylation upon ionizing radiation induces global dissociation of HuR from its target RNAs. This regulation of HuR activity is important for cell survival after IR.