121 Oral - Reproduction and Gametogenesis
Friday April 08, 4:45 PM - 5:00 PM

Authors:
Anna Hakes; Elizabeth Gavis

Affiliation: Princeton University

Keywords:
e. primordial germ cells; u. RNA binding proteins

Germ granules, membraneless organelles containing mRNAs and proteins required for germline development, are a characteristic feature of germ cells. In Drosophila, germ granules form at the posterior of the oocyte and are subsequently segregated to the germ cell progenitors, called the pole cells, which bud from the posterior of the embryo. After pole cell formation, the germ granules increase in size and persist at least until the pole cells coalesce in the gonad. The persistence and evolutionary conservation of germ granules suggest that they play an important role in RNA regulation during germ cell development, but this role is not fully understood. We found that components of the mRNA decay pathway are sequentially recruited to the germ granules as these granules begin to increase in size. This association coincides with a dramatic decrease in the levels of two granule mRNAs, nos and pgc. By contrast, another germ granule mRNA, cycB, is protected from this degradation throughout embryogenesis. Our findings thus suggest that after pole cell formation, the germ granules play a dual role, selectively protecting some mRNAs while promoting the degradation of others, which is distinct from their protective role prior to pole cell formation. Additionally, we have found that the recruitment of mRNA decay proteins to the germ cells is dependent on translation. Together, these data indicate that there is a temporally regulated change in germ granule function in the pole cells, suggesting that the germ granules evolve throughout development to meet the needs of the germ cells. Experiments are in progress to determine what factor is translationally activated to trigger this shift in germ granule function. Since germ granules are one of many types of RNA-rich membraneless organelles, understanding their function in regulating RNA stability can provide general insights into the roles of membraneless organelles in post-transcriptional regulation.