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:
Further reports about: > Ago-miRNA-complex > Argonaute > Argonaute proteins > Cellular > Cellular transporter > Importin > Max Planck Institute > RNA > RNA biology > Small Molecule > cell death > cellular protein factories > genetic information > miRNAs > neurodegenerative disease > noncoding ribonucleic acids
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering