Process may explain why damaged DNA contributes to cancer and other age-related illnesses
As we and other vertebrates age, our DNA accumulates mutations and becomes rearranged, which may result in a variety of age-related illnesses, including cancers.
Biologists Vera Gorbunova and Andei Seluanov have now discovered one reason for the increasing DNA damage: the primary repair process begins to fail with increasing age and is replaced by one that is less accurate.
The findings have been published in the journal PLOS Genetics.
"Scientists have had limited tools to accurately study how DNA repair changes with age," said Gorbunova. "We are now able to measure the efficiency with which cells in mice of different ages repair DNA breaks at the same place in the chromosome."
Gorbunova explained that when mice are young, the breaks in DNA strands are repaired through a process called non-homologous end joining (NHEJ), in which the damage is repaired by gluing the DNA together with no or very little overlap.
However, Gorbunova and Seluanov found that NHEJ began to fail as the mice got older, allowing a less reliable DNA repair process—microhomology-mediated end joining (MMEJ)—to take over. With MMEJ repairs, broken ends are glued together by overlapping similar sequences that are found within the broken DNA ends. This process leads to loss of DNA segments and the wrong pieces being stitched together.
Gorbunova and her team were able to make their observations by working with genetically-modified mice whose cells produce green fluorescent protein (GFP) that glows each time the breaks are repaired. By tracking how many cells glowed green in different tissues, the researchers determined the efficiency of repair.
"We showed two things with these genetically-modified mice," said Gorbunova. "Not only did the efficiency of DNA repair decline with age, but the mice began using a sloppier repair mechanism, leading to more mutations, particularly in the heart and lungs."
DNA breaks occur frequently because animal cells are under constant assault from routine activities in the environment—whether by a blast of X-rays from a visit to the doctor or simply breathing in oxygen—and, as a result, the DNA molecules often get damaged.
Using the genetically modified mice, the research team can now look at how diet, medicines, and different genetic factors also affect DNA repair in mice.
"These mice may very well help us devise novel ways to prevent some of the illnesses associated with aging," said Gorbunova.
Peter Iglinski | Eurek Alert!
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine