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Elucidating the organisation and function of macromolecular complexes in vivo

Supervisor: Dr Tim Weil


Project Summary:

Understanding how cells control spatiotemporal protein synthesis is a fundamental question in biology with strong implications to medical therapeutics. In cells, membrane bound organelles such as the endoplasmic reticulum and Golgi complex enable specialised reactions to occur in compartmentalised micro-environments. Recently, it has become increasingly evident that there exists an additional level of local organisation in the form of non-membrane bound macromolecular organelles or complexes. In the cytoplasm, these complexes function as reaction crucibles and sub-cellular organisational hubs. Composed of proteins and nucleic acids, examples include stress granules, Processing bodies (P bodies), the mitochondrial cloud in Xenopus, Balbiani bodies in zebrafish and P granules in C. elegans. While many of these cytoplasmic complexes are evolutionarily conserved, the specific biological functions of these complexes remain unclear.
Conserved across eukaryotes, P bodies act as localised areas for RNA metabolism. Crucial to this function, these RNA-protein complexes are devoid of ribosomes and contain translational repressors and RNA decay factors. While research has shown the role of P bodies in mRNA storage and degradation, recent studies highlight an additional function in translational regulation. Specifically, work from our lab shows P bodies regulate translation of axis-determining mRNAs through differential partitioning of transcripts between the core and edge of P bodies.
While many studies have implicated P body associated proteins in pathogenesis and essential cellular pathways, an in vivo model to establish a comprehensive understanding of P body organisation and function remains elusive. This studentship would utilise the genetic, biochemical and molecular tools available in Drosophila to define the in vivo molecular mechanisms that regulate P body function.
This interdisciplinary project will develop new approaches that address how RNA-protein complexes function in vivo. For example, to test the differential biophysical and biochemical properties of the P bodies we will work with computational biologist collaborators to identify and experimentally verify required protein motifs. Moreover, this project will use state-of-the-art imaging to examine if in vivo P bodies have similar behaviour and function to tissue culture and in vitro data available. We have already established a reproducible assay for the breakdown of P bodies, which enables visualisation of P bodies under experimental conditions, including changes in temperature, stress, ion concentration and the presence of chaperones. Together, this work would represent the first, and most complete understanding of in vivo macromolecular complexes. 


This is a BBSRC DTP funded Targeted Studentship - please visit the BBSRC DTP website for more information.