DNA Damage Signaling Triggers Degradation of Histone Methyltransferases through APC/CCdh1 in Senescent Cells

• DOI: 10.1016/j.molcel.2011.10.018
• Publication Date: 2011-12-15T15:14:44Z
• Authors: Akiko Takahashi; Yoshinori Imai; Kimi Yamakoshi; Shinji Kuninaka; Naoko Ohtani; Shin Yoshimoto; Satoshi Hori; Makoto Tachibana; Emma Anderton; Takashi Takeuchi; Yoichi Shinkai; Gordon Peters; Hideyuki Saya; Eiji Hara
• Keywords: Cyclin-Dependent Kinase Inhibitor p21; DNA (Cytosine-5-)-Methyltransferase 1; 0303 health sciences; Ubiquitin-Protein Ligase Complexes; Cell Biology; Histone-Lysine N-Methyltransferase; Methylation; Anaphase-Promoting Complex-Cyclosome; Histones; 03 medical and health sciences; Histocompatibility Antigens; Histone Methyltransferases; Dual-Specificity Phosphatases; Humans; DNA (Cytosine-5-)-Methyltransferases; Molecular Biology; Cellular Senescence; DNA Damage; Signal Transduction

Both the DNA damage response (DDR) and epigenetic mechanisms play key roles in the implementation of senescent phenotypes, but very little is known about how these two mechanisms are integrated to establish senescence-associated gene expression. Here we show that, in senescent cells, the DDR induces proteasomal degradation of G9a and GLP, major histone H3K9 mono- and dimethyltransferases, through Cdc14B- and p21(Waf1/Cip1)-dependent activation of APC/C(Cdh1) ubiquitin ligase, thereby causing a global decrease in H3K9 dimethylation, an epigenetic mark for euchromatic gene silencing. Interestingly, induction of IL-6 and IL-8, major players of the senescence-associated secretory phenotype (SASP), correlated with a decline of H3K9 dimethylation around the respective gene promoters and knockdown of Cdh1 abolished IL-6/IL-8 expression in senescent cells, suggesting that the APC/C(Cdh1)-G9a/GLP axis plays crucial roles in aspects of senescent phenotype. These findings establish a role for APC/C(Cdh1) and reveal how the DDR integrates with epigenetic processes to induce senescence-associated gene expression.