title: Subcellular proteomics reveals a role for nucleo-cytoplasmic trafficking at the DNA replication origin activation checkpoint.
abstract: Depletion of DNA replication initiation factors such as CDC7 kinase triggers the origin activation checkpoint in healthy cells and leads to a protective cell cycle arrest at the G1 phase of the mitotic cell division cycle. This protective mechanism is thought to be defective in cancer cells. To investigate how this checkpoint is activated and maintained in healthy cells, we conducted a quantitative SILAC analysis of the nuclear- and cytoplasmic-enriched compartments of CDC7-depleted fibroblasts and compared them to a total cell lysate preparation. Substantial changes in total abundance and/or subcellular location were detected for 124 proteins, including many essential proteins associated with DNA replication/cell cycle. Similar changes in protein abundance and subcellular distribution were observed for various metabolic processes, including oxidative stress, iron metabolism, protein translation and the tricarboxylic acid cycle. This is accompanied by reduced abundance of two karyopherin proteins, suggestive of reduced nuclear import. We propose that altered nucleo-cytoplasmic trafficking plays a key role in the regulation of cell cycle arrest. The results increase understanding of the mechanisms underlying maintenance of the DNA replication origin activation checkpoint and are consistent with our proposal that cell cycle arrest is an actively maintained process that appears to be distributed over various subcellular locations.
authors: Division of Medicine, University College London , Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom.
authors: Claire M
authors: CM
authors: Mulvey
authors: Slavica
authors: S
authors: Tudzarova
authors: Mark
authors: M
authors: Crawford
authors: Gareth H
authors: GH
authors: Williams
authors: Kai
authors: K
authors: Stoeber
authors: Jasminka
authors: J
authors: Godovac-Zimmermann
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002853:Chromatography, Liquid; D003593:Cytoplasm / Q000378:metabolism*; D017931:DNA Primers; D006801:Humans; D040901:Proteomics; D034622:RNA Interference; D018741:Replication Origin; D013347:Subcellular Fractions / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D017931:DNA Primers