Article abstract
Nature Cell Biology 10, 812 - 824 (2008)
Published online: 8 June 2008 | doi:10.1038/ncb1743
Control of HIPK2 stability by ubiquitin ligase Siah-1 and checkpoint kinases ATM and ATR
Melanie Winter1,2, Dirk Sombroek1,2, Ilka Dauth1, Jutta Moehlenbrink1, Karin Scheuermann1, Johanna Crone1 & Thomas G. Hofmann1
Abstract
The tumour suppressor HIPK2 is an important regulator of cell death induced by DNA damage, but how its activity is regulated remains largely unclear. Here we demonstrate that HIPK2 is an unstable protein that colocalizes and interacts with the E3 ubiquitin ligase Siah-1 in unstressed cells. Siah-1 knockdown increases HIPK2 stability and steady-state levels, whereas Siah-1 expression facilitates HIPK2 polyubiquitination, degradation and thereby inactivation. During recovery from sublethal DNA damage, HIPK2, which is stabilized on DNA damage, is degraded through a Siah-1-dependent, p53-controlled pathway. Downregulation of Siah-1 inhibits HIPK2 degradation and recovery from damage, driving the cells into apoptosis. We have also demonstrated that DNA damage triggers disruption of the HIPK2–Siah-1 complex, resulting in HIPK2 stabilization and activation. Disruption of the HIPK2–Siah-1 complex is mediated by the ATM/ATR pathway and involves ATM/ATR-dependent phosphorylation of Siah-1 at Ser 19. Our results provide a molecular framework for HIPK2 regulation in unstressed and damaged cells.
- Cellular Senescence Group, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120 Heidelberg, Germany.
- These authors contributed equally to the study.
Correspondence to: Thomas G. Hofmann1 e-mail: t.hofmann@dkfz.de
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