Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

On the trail of the epigenetic code

12.10.2010
Test system on Drosophila should provide the key to histone function. The genetic inherited material DNA was long viewed as the sole bearer of hereditary information.

The function of its packaging proteins, the histones, was believed to be exclusively structural. Additional genetic information can be stored, however, and passed on to subsequent generations through chemical changes in the DNA or histones.

Scientists from the Max Planck Institute for Biophysical Chemistry in Göttingen have succeeded in creating an experimental system for testing the function of such chemical histone modifications and their influence on the organism. Chemical modifications to the histones may constitute an "epigenetic histone code" that complements the genetic code and decides whether the information from certain regions of the DNA is used or suppressed. (EMBO reports, November 1, 2010, advance online publication)

How do you get a two-metre-long DNA thread into the cell nucleus? By winding it into a ball, of course! The DNA is wound around proteins known as histones, becoming 50,000 times shorter as a result. Other proteins then aggregate on it to form chromatin and, finally, the chromosomes. The latter are the product of an ingenious packaging trick. The five types of histones (H1, H2A, H2B, H3 und H4) fulfil even more tasks, however, and this is what makes them so fascinating. Histones can have small chemical attachments, such as acetyl, methyl and phosphate groups, in different places. These cause the opening of the chromatin, for example, and hence enable the genetic information to be read. Conversely, certain areas of the DNA molecule can be deactivated and rendered unreadable through other modifications, such as the binding of proteins. Scientists refer to this process as "gene silencing". "The histone modifications can intervene in the control of gene activity in this way and, as a result, complement the genetic code," explains Herbert Jäckle, Director of the Max Planck Institute for Biophysical Chemistry in Göttingen.

Every time a cell divides, this modification pattern of the histones is inherited by the daughter cells. The scientists assume that this epigenetic inheritance is controlled by a cell-specific or organ-specific "histone code". "This decides whether the cell machinery has access to the DNA-coded genes or whether the access is blocked," says Jäckle. The scientists would very much like to crack this code: for the production of the histones, hundreds of gene copies are stored in the genome of higher organisms. Therefore, up until now, it appeared to be impossible to switch off these gene copies and replace them with genetically-modified histone variants. Researchers could only create a test system if they managed to do this: if these variants lack certain docking sites, for example for chemical groups, certain modifications to the histones could be prevented and it would then be possible to investigate the extent to which the absence of these modifications leads to diagnosable defects in the organism.

The Max Planck researchers in Göttingen have now succeeded in developing a new method for researching the function of all histone modifications. The cell biologists removed all of the histone genes from the genome of the fruit fly Drosophila melanogaster. As a result, the cells could no longer divide. As occurs with normal cell division, the organism’s genome is still doubled through DNA synthesis but the cell then remains at a standstill in the division cycle and the organism dies. The situation normalises progressively, however, with the increasing number of copies of the four histone genes produced: "Flies with twelve copies of the histone gene cluster ultimately survive and are capable of reproducing," explains Jäckle’s colleague and project leader Alf Herzig.

It had already been established for multicellular organisms that several copies of the histone gene are required for the organism to survive. However, the results obtained by the researchers also indicate that the cell realises during division that histones are lacking, and the division of the cell is then halted despite the fact that DNA has already been doubled - as is the case during all cell division processes. "Communication paths clearly exist between the histone production process and the cell division machinery," says Ufuk Günesdogan, a doctoral student in the department. Most importantly, the researchers now have a test system at their disposal into which histone variants can be channelled for the gradual experimental examination of the function of histone modification and, ultimately, the histone code in the organism. It can only be a matter of time now until the code is finally cracked.

Michael Frewin | alfa
Further information:
http://goto.mpg.de/mpg/news/20101011/

More articles from Life Sciences:

nachricht The birth of a new protein
20.10.2017 | University of Arizona

nachricht Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>