Stochastic Seeding Coupled with mRNA Self-Recruitment Generates Heterogeneous Drosophila Germ Granules.

TitleStochastic Seeding Coupled with mRNA Self-Recruitment Generates Heterogeneous Drosophila Germ Granules.
Publication TypeJournal Article
Year of Publication2018
AuthorsNiepielko, MG, Eagle, WVI, Gavis, ER
JournalCurr Biol
Volume28
Issue12
Pagination1872-1881.e3
Date Published2018 Jun 18
ISSN1879-0445
Abstract

The formation of ribonucleoprotein assemblies called germ granules is a conserved feature of germline development. In Drosophila, germ granules form at the posterior of the oocyte in a specialized cytoplasm called the germ plasm, which specifies germline fate during embryogenesis. mRNAs, including nanos (nos) and polar granule component (pgc), that function in germline development are localized to the germ plasm through their incorporation into germ granules, which deliver them to the primordial germ cells. Germ granules are nucleated by Oskar (Osk) protein and contain varying combinations and quantities of their constituent mRNAs, which are organized as spatially distinct, multi-copy homotypic clusters. The process that gives rise to such heterogeneous yet organized granules remains unknown. Here, we show that individual nos and pgc transcripts can populate the same nascent granule, and these first transcripts then act as seeds, recruiting additional like transcripts to form homotypic clusters. Within a granule, homotypic clusters grow independently of each other but depend on the simultaneous acquisition of additional Osk. Although granules can contain multiple clusters of a particular mRNA, granule mRNA content is dominated by cluster size. These results suggest that the accumulation of mRNAs in the germ plasm is controlled by the mRNAs themselves through their ability to form homotypic clusters; thus, RNA self-association drives germ granule mRNA localization. We propose that a stochastic seeding and self-recruitment mechanism enables granules to simultaneously incorporate many different mRNAs while ensuring that each becomes enriched to a functional threshold.

DOI10.1016/j.cub.2018.04.037
Alternate JournalCurr. Biol.
PubMed ID29861136
PubMed Central IDPMC6008217
Grant ListF32 GM119200 / GM / NIGMS NIH HHS / United States
R01 GM067758 / GM / NIGMS NIH HHS / United States
T32 GM007388 / GM / NIGMS NIH HHS / United States