title: Functional relationship between Claspin and Rad17.
abstract: Claspin was originally identified as a Check1 (Chk1)-interacting protein. Claspin and Rad17 are reportedly involved in the DNA damage-induced phosphorylation of Chk1, a hallmark of checkpoint activation. To understand the cellular functions of Claspin and the functional relationship between Claspin and Rad17, we generated Claspin(-/-) and Claspin(-/-)/RAD17(-) cells using chicken DT40 cells, which contain an exogenously introduced Claspin that can be suppressed by the addition of doxycycline (Dox). In the presence of Dox, Claspin(-/-) cells ceased growth within 2 days, leading to cell death. In addition, a remarkable reduction in the rate of DNA elongation was observed in Claspin-depleted cells, suggesting that Claspin plays a critical role in DNA replication in the absence of exogenous stress. When cells were exposed to methyl methanesulfonate (MMS), a DNA damaging agent, RAD17(-) cells showed a greater defect in checkpoint activation than Claspin(-/-) cells as monitored by progression of cell cycle and phosphorylation of Chk1. Knocking out RAD17 gene showed almost no additive effects on cell death and DNA elongation rates in Claspin-depleted cells.
authors.affiliation: Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585, Japan.
authors.forename: Akari
authors.initials: A
authors.lastname: Yoshimura
authors.forename: Motomu
authors.initials: M
authors.lastname: Akita
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Hosono
authors.forename: Takuya
authors.initials: T
authors.lastname: Abe
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Shusuke
authors.initials: S
authors.lastname: Tada
authors.forename: Masayuki
authors.initials: M
authors.lastname: Seki
authors.forename: Takemi
authors.initials: T
authors.lastname: Enomoto
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002645:Chickens; D004261:DNA Replication / Q000235:genetics; D055786:Gene Knockout Techniques; D006801:Humans
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C488158:CLSPN protein, human; D018797:Cell Cycle Proteins