Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Let’s Stick Together - A Protein Protects Chromosome Bonds

30.03.2005


The protein Mnd2 inhibits premature separation of chromosomes during the formation of gametes. The now published discovery of this regulatory function may help to understand the origin of some common congenital chromosome defects. The project of a team of the University of Vienna funded by the Austrian Science Fund (FWF) contributes to the Campus Vienna Biocenter maintaining a top-level position in the field of cell division research.



During the division of somatic cells (mitosis) newly duplicated chromosomes (sister chromatids) separate and segregate to opposite daughter cells. The cell division, which leads to the formation of gametes (egg and sperm cells), serves a different purpose. In this cell division called meiosis, the two complete sets of chromosomes (maternal and paternal ones) in each body cell are reduced to a single one.

Prof. Franz Klein and his colleague, Ph.D. student Alexandra Penkner from the Department of Chromosome Biology of the Max Perutz Laboratories at the Campus Vienna Biocenter, have now published results on an important regulation of this process in the journal CELL. These findings show that the premature segregation of sister chromatids with lethal consequences are inhibited by a protein named Mnd2.


Sisters Stick Together

The research carried out on the model organism Saccharomyces cerevisiae (yeast) is explained by Prof. Klein, "Until they are separated, the sister chromatids are linked by a protein ring called cohesin. This linkage ensures their correct segregation to the daughter cells later on. We have now discovered an important role of the protein Mnd2 in stabilising this arrangement up to the right moment in the cell division."

The command for opening the cohesin rings, which initiates the division, comes via the anaphase promoting complex (APC/C). Klein explains, "While we worked on Mnd2, colleagues in the USA and Germany isolated Mnd2 as one of 13 subunits of the APC/C. However, the important role of Mnd2 was not revealed. Because only during meiosis, when the gametes are created, does it become essential."

In initial experiments, Ms. Penkner observed defects in meiotic chromosome structure, DNA breaks and premature separation of sister chromatides in cells lacking Mnd2. Such abnormalities may be caused by an irregular activity of the APC/C. To verify this idea, Ms. Penkner conducted clever experiments in which she inactivated the APC/C in yeast cells in addition to Mnd2. Indeed without a functional APC/C, Mnd2 was not anymore required to prevent chromosomal defects.

Braking for Chromosomes

Additional experiments explained why the described damages occurred exclusively during meiosis. An activator of the APC/C (Ama1), which only appears during meiosis, requires Mnd2. It is Ama1, which activates the APC/C too early in the absence of Mnd2 and thus opens the cohesin rings prematurely, that leads to chromosome damage and finally to the death of the cell.

Chromosome damage in meiosis can have lasting consequences. Well-known examples are Down Syndrome patients, for whom the proper division of two chromosomes did not occur during the meiosis of one parent. The fusion of two germ cells, one of which carried two copies of chromosomes 21, gave rise to body cells carrying three chromosomes 21.

The work of Prof. Klein follows an earlier joint study with a team led by Prof. Kim Nasmyth from the Research Institute of Molecular Pathology (IMP) at the Campus Vienna Biocenter. In that research, the role of over 300 proteins during meiosis was analysed. Consequently, Mnd2 was recognised as important meiotic function, which could now be worked out with support from the FWF.

Prof. Franz Klein | alfa
Further information:
http://www.fwf.ac.at/en/press/gametes.html

More articles from Life Sciences:

nachricht New way to look at cell membranes could change the way we study disease
19.11.2018 | University of Oxford

nachricht Controlling organ growth with light
19.11.2018 | European Molecular Biology Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

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...

Im Focus: A Chip with Blood Vessels

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...

Im Focus: A Leap Into Quantum Technology

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...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

New materials: Growing polymer pelts

19.11.2018 | Materials Sciences

Earthquake researchers finalists for supercomputing prize

19.11.2018 | Information Technology

Controlling organ growth with light

19.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>