Live imaging of the Dictyostelium cell cycle reveals widespread S phase during development, a G2 bias in spore differentiation and a premitotic checkpoint

Tetsuya Muramoto, Jonathan R. Chubb

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    44 Citations (Scopus)

    Abstract

    The regulation of the Dictyostelium cell cycle has remained ambiguous owing to difficulties in long-term imaging of motile cells and a lack of markers for defining cell cycle phases. There is controversy over whether cells replicate their DNA during development, and whether spores are in G1 or G2 of the cell cycle. We have introduced a live-cell S-phase marker into Dictyostelium cells that allows us to precisely define cycle phase. We show that during multicellular development, a large proportion of cells undergo nuclear DNA synthesis. Germinating spores enter S phase only after their first mitosis, indicating that spores are in G2. In addition, we demonstrate that Dictyostelium heterochromatin is copied late in S phase and replicates via accumulation of replication factors, rather than recruitment of DNA to pre-existing factories. Analysis of variability in cycle times indicates that regulation of the cycle manifests at a single random transition in G2, and we present the first identified checkpoint in Dictyostelium, which operates at the G2-M transition in response to DNA damage.

    Original languageEnglish
    Pages (from-to)1647-1657
    Number of pages11
    JournalDevelopment
    Volume135
    Issue number9
    DOIs
    Publication statusPublished - 1 May 2008

    Keywords

    • Cell cycle
    • Dictyostelium
    • Checkpoint
    • Replication timing
    • PCNA
    • Cultured human cells
    • DNA replication
    • Radiosensitizing agent
    • De novo
    • Discoideum
    • Caffeine
    • Dynamics
    • Protein
    • Gene
    • Kinase

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