Protein interactors of MEG-1 in C. elegans embryos

In animals with germ plasm, specification of the germline involves “germ granules”, cytoplasmic condensates that enrich maternal transcripts in the germline founder cells. In C. elegans embryos, P granules enrich maternal transcripts, but surprisingly P granules are not essential for germ cell fate specification. Here we have described a second condensate in the C. elegans germ plasm. Like canonical P-bodies found in somatic cells, “germline P-bodies” contain regulators of mRNA decapping and deadenylation and, in addition, the intrinsically-disordered proteins MEG-1 and MEG-2 and the TIS11-family RNA-binding protein POS-1. Embryos lacking meg-1 and meg-2 do not stabilize P-body components, miss-regulate POS-1 targets, miss-specify the germline founder cell, and do not develop a germline. Our findings suggest that specification of the germ line involves at least two distinct condensates that independently enrich and regulate maternal mRNAs in the germline founder cells.