title: Role of Claspin in regulation of nucleotide excision repair factor DDB2.
abstract: The replication checkpoint protein Claspin is important for maintenance of genomic stability and is required for cells to overcome genotoxic stress. Upon UV-induced DNA damage, Claspin is required for activation of the ATR-mediated DNA damage checkpoint response, leading to arrest of DNA replication and inhibition of cell cycle progression. Located at the DNA replication fork, Claspin is also suggested to monitor replication and sense damage. Our present studies in HeLa cells demonstrate associations between the Claspin/ATR-related DNA damage checkpoint response and the global genomic nucleotide excision repair pathway. siRNA-mediated knockdown of Claspin abolishes the UV-induced degradation of DDB2 and impairs the co-localization of DDB2 to DNA damage sites. Thus, the presence of Claspin is required for the total turnover of DNA damage binding protein DDB2, as well as for its functionality in DNA damage recognition. Claspin, however, seems not to be required for maintaining the cellular level of the NER factor XPC and its UV-induced post-translational modifications. Co-localization of XPC with DNA lesions is also intact in the absence of Claspin as is the repair of the UV-induced lesions CPD and 6-4PP. Claspin itself may be directly responsible for physical interaction between the two pathways since Claspin is able to associate with DDB1, DDB2 and XPC. Taken together, these findings reveal physical and functional interplay between Claspin and NER-related proteins and demonstrate crosstalk between the DNA damage checkpoint control and DNA damage repair pathways.
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH 43240, United States. ibba.2@osu.edu
authors.forename: Mette
authors.initials: M
authors.lastname: Praetorius-Ibba
authors.forename: Qi-En
authors.initials: QE
authors.lastname: Wang
authors.forename: Gulzar
authors.initials: G
authors.lastname: Wani
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: El-Mahdy
authors.forename: Qianzheng
authors.initials: Q
authors.lastname: Zhu
authors.forename: Song
authors.initials: S
authors.lastname: Qin
authors.forename: Altaf A
authors.initials: AA
authors.lastname: Wani
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells / Q000528:radiation effects; D006801:Humans; D047468:Immunoprecipitation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011740:Pyrimidine Dimers; D034741:RNA, Small Interfering / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C488158:CLSPN protein, human; D018797:Cell Cycle Proteins; C091435:DDB1 protein, human; C117669:DDB2 protein, human; D004268:DNA-Binding Proteins; D011740:Pyrimidine Dimers; D034741:RNA, Small Interfering; C086984:XPC protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases