Control of HIPK2 stability by ubiquitin ligase Siah-1 and checkpoint kinases ATM and ATR.
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.
Winter
Melanie
M
Cellular Senescence Group, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120 Heidelberg, Germany.
Sombroek
Dirk
D
Dauth
Ilka
I
Moehlenbrink
Jutta
J
Scheuermann
Karin
K
Crone
Johanna
J
Hofmann
Thomas G
TG
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D006801:Humans; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D000098563:Seven in Absentia Proteins
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; D012694:Serine; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins; C115114:HIPK2 protein, human; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases