The endosome as engineer

Description Endosomes use lipid signaling to shape organelles according to nutrient levels A hallmark of eukaryotic cells is that they are compartmentalized into membrane-bound organelles. This allows for the spatial separation of biochemically incompatible processes. Nevertheless, organelles must work together for the cell to function. There has been increasing interest in organelle communication at membrane contact sites—where two organelles are anchored in close apposition by “tether” proteins (1). These contact sites allow the exchange of materials and information between cellular compartments (2). Intriguingly, organelles can also influence one another’s abundance and morphology. Most studies have focused on the role of the endoplasmic reticulum (ER) in shaping other organelles (3). However, on page 1188 of this issue, Jang et al. (4) show that the endosome can reengineer ER shape in response to changing nutrient levels, which in turn affects the morphology and function of additional organelles.