Differential requirements for MCM proteins in DNA replication in Drosophila S2 cells.
BACKGROUND
The MCM2-7 proteins are crucial components of the pre replication complex (preRC) in eukaryotes. Since they are significantly more abundant than other preRC components, we were interested in determining whether the entire cellular content was necessary for DNA replication in vivo.


RESULTS
We performed a systematic depletion of the MCM proteins in Drosophila S2 cells using dsRNA-interference. Reducing MCM2-6 levels by >95-99% had no significant effect on cell cycle distribution or viability. Depletion of MCM7 however caused an S-phase arrest. MCM2-7 depletion produced no change in the number of replication forks as measured by PCNA loading. We also depleted MCM8. This caused a 30% reduction in fork number, but no significant effect on cell cycle distribution or viability. No additive effects were observed by co-depleting MCM8 and MCM5.


CONCLUSIONS
These studies suggest that, in agreement with what has previously been observed for Xenopus in vitro, not all of the cellular content of MCM2-6 proteins is needed for normal cell cycling. They also reveal an unexpected unique role for MCM7. Finally they suggest that MCM8 has a role in DNA replication in S2 cells.
Crevel
Gilles
G
Basic Medical Sciences, St. George's University of London, London, United Kingdom.
Hashimoto
Reina
R
Vass
Sharron
S
Sherkow
Jake
J
Yamaguchi
Masamitsu
M
Heck
Margarete M S
MM
Cotterill
Sue
S
D000818:Animals; D002460:Cell Line; D004261:DNA Replication / Q000502:physiology*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000502:physiology*; D009154:Mutation; D034622:RNA Interference