title: Glucose deprivation is associated with Chk1 degradation through the ubiquitin-proteasome pathway and effective checkpoint response to replication blocks.
abstract: Chk1 plays a key role in the DNA replication checkpoint and in preserving genomic integrity. Previous studies have shown that reduced Chk1 function leads to defects in the checkpoint response and is closely associated with tumorigenesis. Here, we report that glucose deprivation caused the degradation of Chk1 protein without perturbing cell cycle progression. The induction of Chk1 degradation in response to glucose deprivation was observed in various cancer cell lines and in normal human fibroblasts. Therefore, it appears to be a universal phenomenon in mammalian cells. A specific proteasome inhibitor blocked glucose deprivation-induced Chk1 degradation. Ubiquitination of Chk1 was detected, indicating that the proteasome-ubiquitin pathway mediates Chk1 degradation upon glucose deprivation. Mechanistic studies have demonstrated that ATR-dependent phosphorylation of Chk1 at the Ser317 and Ser345 sites is not required, suggesting that the molecular mechanism for Chk1 degradation upon glucose deprivation is distinct from genotoxic stress-induced degradation. Under conditions of glucose deprivation, the cells manifested a defective checkpoint response to replication stress, camptothecin or hydroxyurea. The forced expression of Myc-Chk1 partially rescued the defective response to the replication block upon glucose deprivation. Taken together, our results indicate that glucose deprivation induces ubiquitin-mediated Chk1 degradation and defective checkpoint responses, implying its potential role in genomic instability and tumor development.
authors: Department of Biochemistry, College of Medicine, Dong-A University, Busan, South Korea.
authors: Ae Jeong
authors: AJ
authors: Kim
authors: Hyun-Ju
authors: HJ
authors: Kim
authors: Hye Jin
authors: HJ
authors: Jee
authors: Naree
authors: N
authors: Song
authors: Minjee
authors: M
authors: Kim
authors: Yoe-Sik
authors: YS
authors: Bae
authors: Jay H
authors: JH
authors: Chung
authors: Jeanho
authors: J
authors: Yun
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D004261:DNA Replication / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004795:Enzyme Stability / Q000187:drug effects; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D057809:HEK293 Cells; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D018797:Cell Cycle Proteins; D007976:Leupeptins; D061988:Proteasome Inhibitors; D025801:Ubiquitin; D012694:Serine; D011494:Protein Kinases; C576897:Atr protein, mouse; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex; D005947:Glucose; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde