RNA condensate remodeling during oocyte growth – RNAcore

Spatiotemporal control of maternal mRNAs in early development is critical for cell identity specification. Decades of research have focused on characterizing maternal mRNAs and their consequent protein products in oogenesis and embryogenesis, with less experimental attention dedicated to the biophysics of supramolecular assemblies that mRNAs are packaged into and their dynamic remodelling. Our findings strikingly uncovered that M. musculus and C. elegans maternal mRNAs are stored in ribonucleoprotein condensates that are dynamically remodelled throughout oogenesis. While some mRNAs are sequentially released from condensates to be translated, others are stored and protected for later embryonic development. Here, we propose (1) to systematically identify the remodelled interactions controlling RNA condensate compositional changes during oocyte growth, (2) to dissect how microtubules and RNA polymers regulate condensate supramolecular assembly, dynamics, and material properties, and (3) test how condensate phase separations protect mRNAs from decay. We will utilize our recently developed Fluorescent Activated Particle Sorting method to characterize the transcriptome and proteome of RNA condensates at distinct oocyte growth stages. Structural nodes, multivalent interactions, RNA repeats, and regulators such as microtubules will be manipulated to test their impact on mRNA stability, condensate assembly, remodelling, and physical properties (i.e. viscoelasticity, cluster size, partition coefficient, saturation concentrations). This work would represent the first comprehensive assessment of RNA condensate compositional dynamics and their impact on RNA expression and stability in a cell specification model. Together, these studies will bring paradigm-shifts in our understanding of gene expression control, and reveal the emerging functions of a higher-scale of transcriptome organization that is conserved throughout evolution, from nematodes to mammals.