Ataxin-3 promotes genome integrity by stabilizing Chk1.
The Chk1 protein is essential for genome integrity maintenance and cell survival in eukaryotic cells. After prolonged replication stress, Chk1 can be targeted for proteasomal degradation to terminate checkpoint signaling after DNA repair finishes. To ensure proper activation of DNA damage checkpoint and DNA repair signaling, a steady-state level of Chk1 needs to be retained under physiological conditions. Here, we report a dynamic signaling pathway that tightly regulates Chk1 stability. Under unperturbed conditions and upon DNA damage, ataxin-3 (ATX3) interacts with Chk1 and protects it from DDB1/CUL4A- and FBXO6/CUL1-mediated polyubiquitination and subsequent degradation, thereby promoting DNA repair and checkpoint signaling. Under prolonged replication stress, ATX3 dissociates from Chk1, concomitant with a stronger binding between Chk1 and its E3 ligase, which causes Chk1 proteasomal degradation. ATX3 deficiency results in pronounced reduction of Chk1 abundance, compromised DNA damage response, G2/M checkpoint defect and decreased cell survival after replication stress, which can all be rescued by ectopic expression of ATX3. Taken together, these findings reveal ATX3 to be a novel deubiquitinase of Chk1, providing a new mechanism of Chk1 stabilization in genome integrity maintenance.
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Yingfeng
Y
Tu
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Hongmei
H
Liu
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Xuefei
X
Zhu
CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Hongyan
H
Shen
CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Xiaolu
X
Ma
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Fengli
F
Wang
CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Min
M
Huang
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Juanjuan
J
Gong
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Xiaoling
X
Li
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Yun
Y
Wang
CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Caixia
C
Guo
State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Tie-Shan
TS
Tang
D000067699:Ataxin-3 / Q000235:genetics* / Q000378:metabolism; D000071877:Checkpoint Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D059565:G2 Phase Cell Cycle Checkpoints / Q000235:genetics*; D015894:Genome, Human; D042822:Genomic Instability; D057809:HEK293 Cells; D006801:Humans; D055550:Protein Stability; D059748:Proteolysis; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D054875:Ubiquitination
C114234:CUL4A protein, human; C100318:Cullin 1; D044842:Cullin Proteins; C091435:DDB1 protein, human; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D004247:DNA; C479752:FBXO6 protein, human; D044843:SKP Cullin F-Box Protein Ligases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C092341:ATXN3 protein, human; D000067699:Ataxin-3