RNA Granule Organization

Abstract

Germ granules, specialized ribonucleoprotein particles, are a hallmark of all germ cells. In Drosophila, an estimated 200 mRNAs are enriched in the germ plasm, and some of these have important, often conserved roles in germ cell formation, specification, survival and migration. How mRNAs are spatially distributed within a germ granule and whether their position defines functional properties is unclear. We have used single‐molecule FISH and structured illumination microscopy, a super resolution approach, to show that mRNAs are spatially organized within the granule whereas core germ plasm proteins, such as Vasa, Oskar, Tudor and Aubergine are distributed evenly throughout the granule. Multiple copies of single mRNAs self‐organize into “homotypic clusters” that occupy defined positions within the granule. This organization, which is maintained during embryogenesis and independent of the translational or degradation activity of mRNAs, reveals new regulatory mechanisms for germ plasm mRNA‐protein that may be applicable to other mRNA granules.Support or Funding InformationHoward Hughes Medical Institute and NICHD