RAB-35 regulates distinct steps of trogocytosis in the biting and bitten cell

ABSTRACT Trogocytosis is a form of cellular cannibalism in which a cell “bites” off pieces of another cell. Here, we investigate the molecular mechanisms of a developmentally programmed C. elegans trogocytic event that occurs when endodermal cells bite off and digest pieces of primordial germ cells (PGCs) called lobes. Through a genetic screen, we identify the Rab family small GTPase rab-35 as a central regulator of trogocytosis and show that its function is required in both biting (endodermal) and bitten (PGC) cells. Within endodermal cells, RAB-35 enriches around trogocytosed PGC lobes, promotes the removal of phosphatidylinositol 4,5-bisphosphate (PIP2), and is required for lobe digestion. By contrast, we show that RAB-35 within PGCs works with the ESCRT complex to promote scission of the PGC lobe from the cell body. Our findings identify a new regulator of trogocytosis that has distinct functions in the biting and bitten cells and provide evidence that the bitten cell contributes to the scission of its own membrane. Competing Interest Statement The authors have declared no competing interest.