A nuclear pore-anchored condensate enables germ granule organization and transgenerational epigenetic inheritance

Abstract

Biomolecular condensates, such as stress and germ granules, often contain subcompartments. For instance, the Caenorhabditis elegans germ granule, which localizes near the outer nuclear membrane of germ cell nuclei, is composed of at least four ordered compartments, each housing distinct sets of proteins and RNAs. How these compartments form and why they are spatially ordered remains poorly understood. Here, we show that the conserved DEAD-box RNA helicase DDX-19 defines another compartment of the larger C. elegans germ granule, which we term the D compartment. The D compartment exhibits properties of a liquid condensate and forms between the outer nuclear pore filament and other compartments of the germ granule. Two nuclear pore proteins, NPP-14 and GLEL-1, are required for its formation, suggesting that the D compartment localizes adjacent to the outer nuclear membrane through interactions with the nuclear pore. The loss of DDX-19, NPP-14 or GLEL-1 leads to functional defects, including aberrant formation of the other four germ granule compartments, a loss of germline immortality and dysregulation of small RNA-based transgenerational epigenetic inheritance programs. Hence, we propose that a function of the D compartment is to anchor larger germ granules to nuclear pores, enabling germ granule compartmentalization and promoting transgenerational RNA surveillance.