"Argonaute (AGO) proteins are integral components of most small RNA silencing pathways in plants and metazoans. Previous studies in both model systems have demonstrated an inherent link between AGO levels and the steady state expression of global populations of miRNAs, strongly suggesting a layer of homeostatic control. In an effort to understand this phenomenon, we have set out on, a series of experimental approaches to uncover and characterise the mechanisms underlying AGO post-transcriptional control. Under normal physiological conditions, and in response to viral infection, we will monitor how the turnover and activity of AGO impacts the global small RNA equilibrium in both plants and metazoans. We have identified a potentially conserved mechanism, whereby Cullin RING-E3 ubiquitin Ligases (CRL) negatively regulate AGOs functioning in miRNA-mediated gene repression. Employing both plant and mammalian models systems in a multidisciplinary approach, we aim to dissect the role of CRLs’ activity on small RNA pathways and AGO1 biology, using a range of biochemical, genetic and molecular biology techniques. In addition, we will employ a proteomic-based screen to identify the full degree of AGOs post-translational modifications. Collectively these approaches should unravel novel modes of AGO regulation through the control of subcellular localisation, protein-protein interactions or RISC assembly/recycling. Overall, the proposed systematic investigation of the currently elusive mechanism(s) underlying AGO regulation and small RNA homeostasis will provide greater insights into fundamental aspects of small RNA biology. This is pivotal to further our knowledge regarding the therapeutic, veterinary and agronomical exploitation of these molecules."