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Activation of gene expression by double-stranded RNAs

Published on April 30, 2017   39 min

A selection of talks on Cell Biology

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0:00
Hello, my name is Long-Cheng Li. I'm a professor at the Peking Union Medical College Hospital, of the Chinese Academy of Medical Sciences. The title of my talk today is "Activation of Gene Expression by Double-Stranded RNAs".
0:16
So my topic on small-RNAs or sRNAs, such as siRNAs and the microRNAs are known to trigger an evolutionary conservative phenomenon, known as RNAi. In RNAi, siRNA is either exogenously introduced or produced within the cells are loaded by a protein called Argonaute or Ago in short. The Ago protein would even discard one of the RNA strand in the RNA duplex. And it uses the remaining RNA strand as the guide to form an active complex called RNA-induced silencing complex or RISC. The complex then bonds to complementary mRNA sequences leading to mRNA degradation. If the guide RNA is a microRNA, they often bind to the 3’UTR region of mRNA, resulting in mRNA degradation and/or suppression of the translation. RNAi is mainly a set proximate event. The nuclear function of small RNAs and the protein partners Argonautes is naturally alone, except in plants and in some lower eukaryotes, such as fission yeast and Drosophila. In plants, the small RNA-Ago pathway can initiate lower DNA methylation, a phenomenon known as RNA-directed DNA methylation or RdDM, leading to transcriptional gene silencing. In fission yeast and in Drosophila, RNA pathway can mediate the assembly and maintenance of heterochromatin at the centromere regions, which is required to silence repetitive sequences. However, the nuclear function of this small RNA-Ago pathways in mammalian cells remains a mystery, which will be the topic of my presentation today.

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Activation of gene expression by double-stranded RNAs

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