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 Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>