Related topics: cancer cells · genes · tumor cells · protein · rna

A matter of concentration

Plants can grow whole new organs with the help of pluripotent stem cells throughout their entire lives. When necessary, these stem cells can develop into any type of cell within an organism. The biologist Prof. Dr. Thomas ...

New insight into microRNA function can give gene therapy a boost

Scientists at the University of Eastern Finland and the University of Oxford have shown that small RNA molecules occurring naturally in cells, i.e. microRNAs, are also abundant in cell nuclei. Previously, microRNAs were mainly ...

Screening for genes to improve protein production in yeast

By silencing genes, researchers have managed to increase protein production in yeast significantly. This method can lay the grounds for engineering better yeast production hosts for industries producing biopharmaceutical ...

DNA origami full of potent anticancer agents

One of the most successful techniques to combat multidrug resistance in cancer cells is the downregulation of those genes responsible for drug resistance. Chinese scientists have now developed a nanoplatform that selectively ...

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RNA interference

RNA interference (RNAi) is a system within living cells that helps to control which genes are active and how active they are. Two types of small RNA molecules – microRNA (miRNA) and small interfering RNA (siRNA) – are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to specific other RNAs and either increase or decrease their activity, for example by preventing a messenger RNA from producing a protein. RNA interference has an important role in defending cells against parasitic genes – viruses and transposons – but also in directing development as well as gene expression in general.

The RNAi pathway is found in many eukaryotes including animals and is initiated by the enzyme Dicer, which cleaves long double-stranded RNA (dsRNA) molecules into short fragments of ~20 nucleotides. One of the two strands of each fragment, known as the guide strand, is then incorporated into the RNA-induced silencing complex (RISC). The most well-studied outcome is post-transcriptional gene silencing, which occurs when the guide strand base pairs with a complementary sequence of a messenger RNA molecule and induces cleavage by Argonaute, the catalytic component of the RISC complex. This process is known to spread systemically throughout the organism despite initially limited molar concentrations of siRNA.

The selective and robust effect of RNAi on gene expression makes it a valuable research tool, both in cell culture and in living organisms because synthetic dsRNA introduced into cells can induce suppression of specific genes of interest. RNAi may also be used for large-scale screens that systematically shut down each gene in the cell, which can help identify the components necessary for a particular cellular process or an event such as cell division. Exploitation of the pathway is also a promising tool in biotechnology and medicine.

Historically, RNA interference was known by other names, including post transcriptional gene silencing, and quelling. Only after these apparently unrelated processes were fully understood did it become clear that they all described the RNAi phenomenon. In 2006, Andrew Fire and Craig C. Mello shared the Nobel Prize in Physiology or Medicine for their work on RNA interference in the nematode worm C. elegans, which they published in 1998.

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