Investigating processing body condensation, material properties and function during early Drosophila development

How cells control spatiotemporal protein synthesis is a biological phenomenon with broad implications in physiology, pathology, and therapeutics. Cellular material can be organised into membrane-bound or membrane-less compartments. The latter, commonly known as biomolecular condensates, often contain ribonucleoprotein assemblies that form via liquid-liquid phase separation. Conserved across eukaryotes, Processing bodies (P bodies) are cytoplasmic biomolecular condensates which act as hubs for RNA regulation including storage, translation, and degradation. During Drosophila oogenesis, several maternal mRNAs are stored and translationally repressed inside P bodies before they are translated and degraded in the early embryo. How P bodies differentially regulate maternal RNAs is not fully understood. Using a combination of in vivo and in vitro assays, I show that P bodies in the mature oocyte exist as multilayered viscoelastic condensates that are regulated by synergistic, multivalent interactions between structurally distinct protein and RNA molecules. I also demonstrate that the gel-like biophysical state of P bodies allows for the storage of bicoid, a key maternal transcript needed for embryonic development. Using pharmacological disruption and live imaging, I show that large scale cytoplasmic reorganisation causes P body dispersal during the oocyte to embryo transition to release the stored maternal mRNAs. Finally, in the early embryo, using live imaging and biochemical analyses, I show that P bodies re-form into smaller sized, highly dynamic condensates with altered post-translational and biochemical modifications. Taken together, developmental cues coordinate synergistic macromolecular interactions and cytoplasmic modifications to differentially regulate RNAs through P body phase transitions during early Drosophila development.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2020

Author dc:creator

• Meenakshi Sundaram, Sankaranarayanan

Advisor dc:contributor.advisor

• Weil, Tim

• Phase separation
• Biomolecular condensates
• Drosophila development
• RNA storage and translation
• Biophysics

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/fa3c24fd-93af-4a3a-b7af-578400b1e989/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.60090

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/312989