Like DNA, centrioles need to duplicate only once per cell cycle. Rogers et al. uncover a long-sought mechanism that limits centriole copying, showing that it depends on the timely demolition of a protein that spurs the organelles' replication.
The study will appear in the January 26, 2009 issue of the Journal of Cell Biology and online at www.jcb.org.
Centrioles start reproducing themselves during G1 or S phase. What prevents the organelles from xeroxing themselves again and again has puzzled researchers for more than a decade. The process could be analogous to the mechanism for controlling DNA replication. There, a licensing factor preps the DNA for duplication. During DNA synthesis, the factor gets tagged with ubiquitin molecules that prompt its destruction, thus preventing another round of copying.
To determine whether a similar mechanism keeps centrioles in check, Rogers et al. blocked Drosophila cells' production of different proteins that combine to form a ubiquitin-adding complex. Loss of one of these proteins, Slimb, allowed cells to fashion extra centrioles, the researchers found.
Slimb's target, the team showed, is the enzyme Plk4, which sports a Slimb-binding motif. Plk4 levels on the centrioles peaked during mitosis, and the enzyme vanished from the organelles by S phase. However, a mutant form of Plk4 that Slimb couldn't latch onto clung to the centrioles throughout the cell cycle and caused their over-duplication.
Plk4 serves as a licensing factor for centriole copying, Rogers et al. suggest. During mitosis, it sets the stage for the next cell division by phosphorylating an unidentified protein (or proteins) that will later instigate centriole duplication. Slimb and its protein partners then ubiquitinate Plk4, so that no enzyme remains on the centrioles by the time they are ready for copying. Thus, the organelles are duplicated once only. Tumor cells often bypass the limit on centriole duplication, and the work suggests that drugs to restrict the organelles' replication might hold promise as cancer treatments.
About the Journal of Cell Biology
Founded in 1955, the Journal of Cell Biology (JCB) is published by the Rockefeller University Press. All editorial decisions on manuscripts submitted are made by active scientists. JCB content is posted to PubMed Central, where it is available to the public for free six months after publication. Authors retain copyright of their published works and third parties may reuse the content for non-commercial purposes under a creative commons license. For more information, please visit www.jcb.org.
Rogers, G.C., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200808049.
Nonstop Tranport of Cargo in Nanomachines
20.11.2018 | Max-Planck-Institut für molekulare Zellbiologie und Genetik
Researchers find social cultures in chimpanzees
20.11.2018 | Universität Leipzig
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
20.11.2018 | Life Sciences
20.11.2018 | Life Sciences
20.11.2018 | Physics and Astronomy