Bridging the gap between organelles: Membrane contact sites as regulator of endocytic dynamics.

Endocytosis controls the internalization of molecules, receptors and membrane components, thereby regulating nutrient uptake, signaling and membrane composition. Increasing evidence shows that trafficking of endocytic cargo is coordinated by membrane contact sites (MCSs). Rather than passive bridges, MCSs act as dynamic platforms that organize communication between organelles, integrating metabolic and biochemical signals with spatial precision. Their ability to locally remodel membranes and generate spatially confined signaling domains directly shapes endocytic and endo-lysosomal trafficking. MCSs are also highly adaptive: they remodel in response to extracellular cues such as growth factors and can be exploited by pathogens to create replication-permissive niches, positioning MCSs as central hubs of intracellular organization and communication.