Acidocalcisome is required for autophagy in Trypanosoma brucei

In Trypanosoma brucei, an early divergent protozoan parasite , we discovered a previously unappreciated function of the acidocalcisome, a lysosome-related organelle characterized by acidic pH and large content of Ca 2+ and polyphosphates, in autophagy regulation. Starvation- and chemical-induced autophagy is accompanied with acidocalcisome acidification, and blocking the acidification completely inhibits autophagosome formation.

Blocking acidocalcisome biogenesis by depleting the adaptor protein-3 complex, which does not affect lysosome biogenesis or function, also inhibits autophagy. Overall, our results support the role of the acidocalcisome, a conserved organelle from bacteria to human, as a relevant regulator in autophagy.