The proteins ensuring genome protection

Feb 12, 2012

Researchers from the University of Geneva (UNIGE), Switzerland, have discovered the crucial role of two proteins in developing a cell 'anti-enzyme shield'. This protection system, which operates at the level of molecular 'caps' named telomeres, prevents cells from treating chromosome ends like accidental DNA breaks and 'repairing' them. Joining chromosome ends would, indeed, lead to tumor formation. This study, carried out by Cyril Ribeyre and led by David Shore, professor of molecular biology, is published in the revue Nature Structural & Molecular Biology.

Each of our contains two huge DNA strands, segmented into parts that are packaged within chromosomes. Each chromosome end, however, becomes vulnerable to specific enzymes that target accidental in need of repair. The cell is, indeed, equipped with a sensitive surveillance system that recognizes and corrects abnormalities occurring within our genome. This system includes patrolling proteins, molecules that set off an alarm, as well as damage-repairing enzymes.

In order to escape the cellular mechanisms that detect and repair damaged DNA, the ends of our chromosomes are covered by molecular 'caps' called telomeres. These complexes, formed of proteins and repetitive DNA, constitute an 'anti-enzyme shield' that protects . Inadvertent end joining would indeed lead to chromosome breakage and rearrangement during cell division, processes that are known to drive .

Restraining the zeal of repair enzymes

Cyril Ribeyre and David Shore, from the Department of of the UNIGE, have discovered that Rif1 and Rif2, two related proteins that bind telomeres, deactivate the alarm of the DNA repair surveillance system. 'Telomeres interact with many molecules. We had identified several biochemical players, but we didn't know how they functioned', says Professor Shore, member of the National Center of Competence in Research Frontiers in Genetics. 'We have now established that Rif1 and Rif2 prevent the binding of specific proteins involved in setting off this alarm, which inhibits an enzymatic cascade at an early stage in the process'.

This local 'anti-enzyme shield' seems to extend to neighboring regions. 'Telomeres of adjacent chromosomes probably benefit from this protective system, in case they undergo severe damage', suggests Professor Shore.

These two related molecules had already been analyzed and part of their functions uncovered by the researcher's team. 'We knew that Rif1 and Rif2 were involved in regulating telomere length, which determines the life span of the cell. Both of them were also suspected to take part in the telomeric cap formation', details Cyril Ribeyre.

The multiple activities of Rif1 and Rif2 thus contribute to ensure the optimal functioning of telomeres with respect to their roles –all essential- within the cell.

Explore further: Life's extremists may be an untapped source of antibacterial drugs

Provided by University of Geneva

5 /5 (3 votes)

Related Stories

Study: Cells prevent DNA repair

Nov 23, 2005

Scientists say they've discovered cells co-opt the machinery that usually repairs broken strands of DNA to protect the integrity of chromosomes.

Common weed could provide clues on aging and cancer

Oct 26, 2009

A common weed and human cancer cells could provide some very uncommon details about DNA structure and its relationship with telomeres and how they affect cellular aging and cancer, according to a team led by scientists from ...

Recommended for you

Cohesin molecule safeguards cell division

Nov 21, 2014

The cohesin molecule ensures the proper distribution of DNA during cell division. Scientists at the Research Institute of Molecular Pathology (IMP) in Vienna can now prove the concept of its carabiner-like ...

Nail stem cells prove more versatile than press ons

Nov 21, 2014

There are plenty of body parts that don't grow back when you lose them. Nails are an exception, and a new study published in the Proceedings of the National Academy of Sciences (PNAS) reveals some of the r ...

Scientists develop 3-D model of regulator protein bax

Nov 21, 2014

Scientists at Freie Universität Berlin, the University of Tubingen, and the Swiss Federal Institute of Technology in Zurich (ETH) provide a new 3D model of the protein Bax, a key regulator of cell death. When active, Bax ...

Researchers unwind the mysteries of the cellular clock

Nov 20, 2014

Human existence is basically circadian. Most of us wake in the morning, sleep in the evening, and eat in between. Body temperature, metabolism, and hormone levels all fluctuate throughout the day, and it ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.