SciLifeLab Fellows seminar series: Rewiring the posttranscriptional networks of the host cell
Speaker: Alfredo Castello, University of Oxford, UK
RNA associates with RNA-binding proteins (RBPs) from synthesis to decay, forming dynamic ribonucleoproteins that orchestrate gene expression. While essential for RNA life cycle, the repertoire of RBPs has remained largely unknown. Using a novel proteomic-based, system-wide approach termed RNA interactome capture, we revealed the near-complete census of human RBPs (RBPome). Applied to steady-state HeLa cells, RNA interactome capture added hundreds of novel members to the previously known repertoire of RBPs (Castello et al., Cell, 2012). While the host cell dedicates more than 1,500 proteins to RNA metabolism, viral genomes typically encode a dozen, only a handful of which are RBPs. Viruses have thus developed sophisticated mechanisms to hijack the host resources to support viral RNA replication, translation and encapsidation. To identify the key host RBPs for viral infection, we have applied “RNA interactome capture” [1-2] to cells infected with the RNA virus, sindbis (SINV). Our data reveal a global remodelling of the host RNA-binding proteome (“RBPome”) in response to infection. Changes in protein-RNA interactions upon infection are almost exclusively due to differential RNA-binding activity and not linked to alterations in protein abundance. Functional assays demonstrate that host RBPs responding to infection play critical roles in virus biology. In summary, our study reveals the global landscape of RBP activities operating in SINV-infected cells, highlighting dozens of RBPs as potential host-based therapeutic targets.
My PhD studies in Dr. Luis Carrasco’s lab (CBMSO – Madrid) focused on deciphering the mechanisms used by animal viruses to manipulate host cell gene expression. My research covered different viruses, including HIV-1, poliovirus, vaccinia virus and Sindbis virus. The conclusion of this work is that single viral proteins, such as poliovirus 2A protease, can modulate the host RNA biology at multiple steps, including translation, RNA export, splicing and translation, promote viral protein synthesis and avoid the antiviral response. During my postdoctoral work at Matthias Hentze lab (EMBL, Heidelberg) I developed a new method that allowed the identification of the “near complete” repertoire of cellular RNA binding proteins and how these proteins interact with RNA. These works, published in “Cell, Mol Cell, Nature Protocols, NSMB and other top journals, represented a breakthrough in our understanding on protein-RNA interactions, revealing hundreds of unorthodox RBPs that link RNA biology with other cellular processes such as intermediary metabolism, autophagy, cell cycle, response to virus, innate immunity, signalling and cytoskeleton. The role of some of these proteins in RNA metabolism has been explored by independent groups and the results suggest that RNA binding can regulate the activity of the unorthodox RBP, opening an important question: is the protein binding the RNA or the RNA binding the protein? I am currently principal investigator at the Department of Biochemistry in the University of Oxford funded by the prestigious MRC Career Development Award. My laboratory is using RNA interactome capture and other state-of-the-art methods in RNA biology to understand the dynamic responses of the “RBPome” to changes in cell’s state, including infection; and to decipher the role of posttranslational networks in cell-fate decisions.
Date: June 12
Venue: Air&Fire auditorium, SciLifeLab Solna
Host: Vicent Pelechano
This seminar is part of a seminar series hosted by SciLifeLab Fellows