Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Cellular transporter involved in gene silencing - Importin guides switch molecules to their targets

Specific gene-silencing is involved in the development of cancer and plays an essential role in gene regulation. Small noncoding ribonucleic acids (miRNAs) are important regulators of genes.

In order to switch off a gene, they interact with so called Argonaute proteins - the subsequent complex induces the shutdown or even degradation of the genetic information. Until now, how this molecular switch works was widely unknown. Scientists of the Max Planck Institute of Biochemistry have now identified the protein Importin 8 as a central factor, that facilitates the switch molecule to find its target (Cell (2009), Cell 6th February, 2009).

Ribonucleic acids (RNAs) carry as messenger-RNAs (mRNAs) genetic information from DNA to cellular protein factories, where they are translated into proteins. But they also have important regulatory functions: Small noncoding RNAs (miRNAs) influence mRNA stability and are able to switch off genes by stalling their translation into proteins. Defects of these regulation processes may lead to cancer and neurodegenerative diseases. Therefore miRNAs are important objects of research and - in the future - could become the basis for new therapeutic strategies.

However, miRNAs can't shut off genes on their own: They need to form complexes with other proteins. As far as humans are concerned, the argonaute protein Ago-2 is the key cellular binding partner of miRNAs: The Ago-miRNA complex binds to mRNA and impedes their translation into proteins - either by blocking the translation process or by initiating RNA decomposition. "While there are a lot of studies concerning miRNA processing, the target mRNA recognition and binding by the Ago-miRNA-complex is only poorly understood", says Gunter Meister, the head of the research group "RNA biology" at the Max Planck Institute. Now his group has identified the first protein factor which is required for gene-silencing by Ago-miRNA-complexes: Importin 8.

Importin 8 interacts with Ago and miRNA and is necessary for the binding of the Ago-miRNA-complex to a variety of mRNA targets: In the cytoplasm - i.e. the intracellular space outside the nucleus - it recruits the complex to its target, allowing for efficient and specific gene-silencing. "Without Importin 8 no mRNA deactivation is possible", points Lasse Weinmann out, who conducted the study as part of his PhD thesis.

Furthermore, the scientists discovered a second mode of action of Importin 8: Importins are molecules that are responsible for the transport of proteins into the nucleus. "As we realised that our new factor is an Importin, it was an obvious supposition that transport processes might play a role in gene-silencing", explains Meister. Indeed the scientists proved that Importin 8 is involved in the transport of Ago-miRNA-complexes into the nucleus. This is especially interesting, because over the past years there have been controversial discussions as to whether or not small noncoding RNAs occur in the nucleus. "Our findings indicate that the Ago-miRNA-complex in the nucleus must serve a purpose. Possibly it is involved in gene regulation, too. But it is also conceivable, that there are other, yet unknown, functions", says Meister, "our results are a beginning to solving these questions".

Original Publication:
Weinmann et al.: Importin Is a Gene Silencing Factor that Targets Argonaute Proteins to Distinct mRNAs; Cell. 2009 Feb 6;136(3):496-507.
Dr. Gunter Meister
RNA Biology
Dr. Monika Gödde/Eva-Maria Diehl
Public Relations
Max Planck Institute of Biochemistry
Am Klopferpsitz 18
82152 Martinsried, Germany
Phone: +49 (89) 8578 2824

Eva-Maria Diehl | Max-Planck-Gesellschaft
Further information:

More articles from Life Sciences:

nachricht Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences

nachricht Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>