In order for the body to grow, reproduce and remain cancer free, the cells of the body must have a mechanism for both detecting DNA damage and a feedback mechanism for telling the rest of the cells machinery to stop what its doing until the damage may be fixed. This feedback mechanism relies on checkpoints during different stages of the cells division cycle. Eric Brown and David Baltimore at the California Institute of Technology (Pasadena, CA) have now further defined how the ATR kinase participates in this feedback mechanism as a member of the DNA damage checkpoint machinery. Their study, which appears in the March 1st issue of Genes & Development, utilizes a novel mouse model to produce mouse cells that lack the ATR kinase. The ATR deficient cells have major defects in cell cycle checkpoint regulation and halting the cell cycle. These mouse cells proceed dangerously through the cell division cycle with chromosome breaks, demonstrating a role for ATR in maintaining the integrity of DNA.
ATR, and a similar protein ATM, have previously been shown to be involved in the response to DNA damage. However previous experiments to determine the role of ATR in preventing cells with damaged DNA from dividing have been contradictory and the precise roles of these proteins have remained obscure. The previous attempts to determine the role of ATR were hindered by the inviability of ATR deficient mice. In this report, the authors use a clever modification of the mouse knockout technology to create cells that can be forced to lose the ATR gene at will.
Cells lacking ATR and ATM did not properly halt the cell division cycle in response to ionizing radiation, a potent DNA damage-inducing agent. Both ATR and ATM contributed to the checkpoint control soon after DNA damage, but ATR was responsible for regulating the control later in the cell cycle. ATR was also important for regulating a checkpoint signaling pathway previously described in yeast that is initiated by stalled DNA replication. Surprisingly though, ATR was not essential for cell cycle arrest in response to incomplete DNA replication, implying that an additional mechanism must be a work. Brown & Baltimore go on to show that when ATR is absent, inhibited DNA replication causes the formation of a very serious form of damage known as double strand breaks. This suggests that while ATR is dispensable for the cell cycle delay in response to incomplete DNA replication, it is essential for ensuring the cells leaving this delay are free of DNA damage.
Michele McDonough | EurekAlert!
NUI Galway highlights reproductive flexibility in hydractinia, a Galway bay jellyfish
24.02.2020 | National University of Ireland Galway
Shaping the rings of molecules
24.02.2020 | University of Montreal
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices
The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...
Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.
Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.
After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.
"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
24.02.2020 | Life Sciences
24.02.2020 | Materials Sciences
24.02.2020 | Earth Sciences