Developmentally programmed germ cell remodeling by endodermal cell cannibalism

Primordial germ cells (PGCs) in many species associate intimately with endodermal cells, bu the significance of such interactions is largely unexplored. Here, we show that C. elegans PGCs form lobes that are removed and digested by endodermal cells, dramatically altering PGC size and mitochondrial content. We demonstrate that endodermal cells do not scavenge lobes PGCs shed, but rather, actively remove lobes from the cell body. CED-10/Rac1-induced actin, DYN-1/dynamin, and LST-4/SNX9 transiently surround lobe necks and are required within endodermal cells for lobe scission, suggesting that scission occurs through a mechanism resembling vesicle endocytosis. These findings reveal an unexpected role for endoderm in altering the contents of embryonic PGCs, and define a form of developmentally programmed cell remodeling involving intercellular cannibalism. Active roles for engulfing cells have been proposed in several neuronal remodeling events, suggesting that intercellular cannibalism may be a more widespread method used to shape cells.