Related Experiment Video

Updated: Jul 12, 2026

Hybrid Ensemble and Single-molecule Assay to Image the Motion of Fully Reconstituted CMG
10:11

Hybrid Ensemble and Single-molecule Assay to Image the Motion of Fully Reconstituted CMG

Published on: July 26, 2024

Differential requirements for MCM proteins in DNA replication in Drosophila S2 cells

Gilles Crevel1, Reina Hashimoto, Sharron Vass

  • 1Basic Medical Sciences, St. George's University of London, London, United Kingdom.

Plos One
|September 6, 2007
PubMed
Abstract

Insights

Most MCM2-6 proteins are not essential for DNA replication in Drosophila cells, but MCM7 depletion causes S-phase arrest, revealing unique roles and the necessity of MCM8 for DNA replication.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • The minichromosome maintenance (MCM) 2-7 proteins are essential components of the eukaryotic pre-replication complex (preRC).
  • Their high abundance suggests that not all cellular content may be required for DNA replication.
  • Investigating the necessity of MCM proteins for DNA replication in vivo is crucial.

Purpose of the Study:

  • To determine if the entire cellular content of MCM2-7 proteins is necessary for DNA replication in vivo.
  • To investigate the specific roles of individual MCM proteins, including MCM8, in DNA replication.

Main Methods:

  • Systematic depletion of MCM proteins in Drosophila S2 cells using dsRNA-interference.
  • Analysis of cell cycle distribution and viability post-depletion.
  • Measurement of replication fork numbers via PCNA loading.

Main Results:

  • Over 95-99% depletion of MCM2-6 proteins showed no significant effect on cell cycle or viability.
  • MCM7 depletion resulted in an S-phase arrest.
  • MCM2-7 depletion did not alter replication fork numbers.
  • MCM8 depletion reduced fork number by 30% without affecting cell cycle or viability.
  • No additive effects were observed when co-depleting MCM8 and MCM5.

Conclusions:

  • A significant portion of cellular MCM2-6 proteins is not required for normal cell cycling in Drosophila, aligning with in vitro Xenopus studies.
  • MCM7 plays a unique and essential role in DNA replication.
  • MCM8 is implicated in DNA replication in Drosophila S2 cells.

More Related Videos

Visualization of DNA Replication in the Vertebrate Model System DT40 using the DNA Fiber Technique07:18

Visualization of DNA Replication in the Vertebrate Model System DT40 using the DNA Fiber Technique

Published on: October 27, 2011

Preparation of Drosophila S2 cells for Light Microscopy09:39

Preparation of Drosophila S2 cells for Light Microscopy

Published on: June 3, 2010

Related Concept Videos

S-Cdk Initiates DNA Replication02:38

S-Cdk Initiates DNA Replication

The cell cycle is a series of events leading to DNA duplication followed by the division of cell content to form two daughter cells. The cell cycle progresses in four stages—the cell increases in size (gap 1 or G1-phase), duplicates its DNA (synthesis or S-phase), prepares to divide (gap 2 or G2-phase), and divides (mitosis or M-phase).
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
Polytene Chromosomes02:04

Polytene Chromosomes

Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...
The Ratio of X Chromosome to Autosomes02:45

The Ratio of X Chromosome to Autosomes

In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.  
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Condensins02:15

Condensins

Condensins are large protein complexes that use ATP to fuel the assembly of chromosomes during mitosis. They transform the tangled, shapeless mass of post-interphase DNA into individualized chromosomes by compacting, organizing, and segregating chromosomal DNA.
The plant and animal cells contain two types of condensin complexes—condensin I and condensin II. Both complexes have five subunits: two SMC (Structural Maintenance of Chromosomes) subunits, a kleisin subunit, and two HEAT-repeat...
Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
The Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...