Pihán, Philippe, Milani, Mateus, Hetz, Claudio
For a long time since their discovery by Christian de Duve in the 1950s, lysosomes have been referred to almost exclusively as passive garbage bags; the endpoint in the degradation of intra- and extracellular cargo. The catabolic function of lysosomes is accomplished by an array of more than 60 acid hydrolases, which together break down a wide variety of biological macromolecules, including proteins, lipids, carbohydrates, and nucleic acids, for reutilization in the metabolic processes of the cell. For their optimal function, these enzymes require an acidic intraluminal pH of ~4.5, which is maintained by the joint action of a proton pump, the vacuolar H+-ATPase, and several ion channels embedded in the lysosomal limiting membrane. Nowadays, lysosomes are envisioned as complex signaling hubs, integrating diverse stimuli about the cell’s metabolic status to coordinate different adaptive responses (Ballabio and Bonifacino, 2020). The lysosome can also induce cell death signals in response to certain conditions, such as infections and treatment with lysosomotropic drugs, which leads to lysosomal membrane permeabilization (LMP) and the release of cathepsins, resulting in lysosomal-mediated cell death.
Pihán, P., Milani, M., & Hetz, C. (2022). Proapoptotic RECS1: a requisite gateway to lysosomal dysfunction and death. Neural Regeneration Research, 17(12), 2695.