Functional roles of the Caenorhabditis elegans Y-box binding protein, CEY-3 in post-transcriptional gene regulation during development

In many tissues, post-transcriptional gene regulation (PTGR) is a particularly important mechanism for regulating gene expression. Binding of RNA to RNA-binding proteins (RBPs) is key to controlling mRNA localization, translation and turnover. We have been using the Caenorhabditis elegans model system to study a conserved family of C. elegans cold-shock (Y-box) RNA-binding proteins (CEYs). CEYs are expressed in the germlines but unexpectedly, we identified that C. elegans lacking CEY-2 is sensitive to heat stress, and that the proteins CEY-2 and CEY-3 are localized to some neurons upon exposure to elevated temperatures. This data suggests that the C. elegans Y-box family of proteins have broad functions including during heat stress condition.
   
   CEYs are also required for the integrity and stability of the P granules. Loss of CEY-2 or CEY-3 results in a significant reduction in progeny number and they function redundantly to reduce brood size and increase embryonic lethality. CEY-3 is predominantly express in the gonads where it localizes to RNA-rich perinuclear cytoplasmic granules (P granules). Moreover, we identified the protein interactors of CEY-3 by mass spectrometry-based immunoprecipitation proteomics. Interestingly two of the interactors, non-muscle myosin-2 (NMY-2) and actin (ACT-2) known as actin cytoskeleton, were found to be required for localization of P granule components including PGL-1, IFET-1, CAR-1, CEY-2 and CEY-3 into oocytes. This suggests that CEY-3 may function as adapter protein to connect between the P granules and NMY-2 for the localization of P granule components to the site of translation.