title: Human Timeless and Tipin stabilize replication forks and facilitate sister-chromatid cohesion.
abstract: The Timeless-Tipin protein complex has been reported to be important for replication checkpoint and normal DNA replication processes. However, the precise mechanisms by which Timeless-Tipin preserves genomic integrity are largely unclear. Here, we describe the roles of Timeless-Tipin in replication fork stabilization and sister chromatid cohesion. We show in human cells that Timeless is recruited to replication origin regions and dissociate from them as replication proceeds. Cdc45, which is known to be required for replication fork progression, shows similar patterns of origin association to those of Timeless. Depletion of Timeless-Tipin causes chromosome fragmentation and defects in damage repair in response to fork collapse, suggesting that it is required for replication fork maintenance under stress. We also demonstrate that depletion of Timeless-Tipin impairs sister chromatid cohesion and causes a defect in mitotic progression. Consistently, Timeless-Tipin co-purifies with cohesin subunits and is required for their stable association with chromatin during S phase. Timeless associates with the cohesion-promoting DNA helicase ChlR1, which, when overexpressed, partially alleviates the cohesion defect of cells depleted of Timeless-Tipin. These results suggest that Timeless-Tipin functions as a replication fork stabilizer that couples DNA replication with sister chromatid cohesion established at replication forks.
authors.affiliation: Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Leman
authors.forename: Chiaki
authors.initials: C
authors.lastname: Noguchi
authors.forename: Candice Y
authors.initials: CY
authors.lastname: Lee
authors.forename: Eishi
authors.initials: E
authors.lastname: Noguchi
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002842:Chromatids / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects / Q000235:genetics*; D004268:DNA-Binding Proteins; D016521:Electrophoresis, Gel, Pulsed-Field; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D006918:Hydroxyurea / Q000633:toxicity; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D034741:RNA, Small Interfering; D000097722:Cohesins
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D053487:DEAD-box RNA Helicases; D004268:DNA-Binding Proteins; D006918:Hydroxyurea; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D000097722:Cohesins; C113571:CDC45 protein, human; C509769:TIMELESS protein, human; C516227:Tipin protein, human