Non-coding RNAs and AGOs

in Health and Disease

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October 2021

miRNA biogenesis 

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Illustrated by Markus Hafner (Adapted from Bartel 2018 Cell)

Argonaute (AGO) proteins are essential in RNA interference (RNAi). AGOs are loaded with small interfering RNAs (siRNAs) or microRNAs (miRNAs), and are the core components of RNA induced silencing complex (RISC). The small RNAs guide the AGO ribonucleoprotein (RNP) to (partially) complementary target RNAs resulting in gene silencing.

miRNA silencing in mammals has been mainly studied as a cytoplasmic phenomenon. It was, however, suggested that in mammalian cell nuclei AGO-miRNAs also contribute to gene silencing. In the lab, we are aiming to unravel the mechanisms/ significance of nuclear RNAi in healthy development as well as in cancers.  

Nuclear RNAi in development 

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We previously found that stem cells have high levels of AGO2 in the nucleus (Sarshad et al., Mol Cell, 2018). In order to understand the molecular mechanisms of nuclear AGOs during mouse development we are investigating the dynamics of nuclear AGOs throughout entire mouse development.

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Nuclear RNAi in cancers 

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A goal in the lab is to screen cancer systems from different origins - from cell lines to patient samples - in order to define the extent/functions of nuclear RNAi. We are using cellular fractionation assays in order to separate the cytoplasmic fraction from the nuclear fractions and tracing AGO2 – a key cofactor for RNA interference (RNAi). AGO2, when loaded with siRNAs, has a functional endonuclease domain, which is able to slice the target RNA and efficently silence gene expression.

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