Putting Your Best Egg Forward

Abstract

In a recent issue of Nature, Bohnert and Kenyon (2017) describe a signaling pathway that prevents transgenerational inheritance of cytoplasmic protein aggregates. Fertilizing sperm trigger aggregate clearance in the ovum by a microautophagy-like effector mechanism mediated by inter-organelle communication between lysosomes and mitochondria.

Figure 1.. Aggregate Clearance in C. elegans Oocytes

(Top) Signaling pathway controlling the expression of V-ATPase subunits in C. elegans oocytes upon fertilization. Activation of a G protein (gray circle)-coupled receptor (gray serpentine shape) by sperm-derived ligands (yellow circles) leads to the acidification of lysosomes in mature oocytes. Acidified lysosomes engulf cytosolic protein aggregates (arbitrarily shown as ordered) by a microautophagy-like process. GLD-1 binds to the untranslated regions (UTRs) of mRNAs encoding V-ATPase subunits, repressing their translation (red bar-headed arrow). (Bottom) Metabolic and morphological changes that C. elegans oocyte mitochondria undergo as a result of lysosome acidification during fertilization. ROS, reactive oxygen species; J, electrochemical potential across the inner mitochondrial membrane. See Bohnert and Kenyon (2017) for additional experimental evidence supporting these working models. Figure by Charlene Chan.