Christian de Duve discovered the lysosome in 1955 through cell fractionation: a dense membrane-bound fraction carrying “latent” acid hydrolases. He won the 1974 Nobel Prize for the work. For decades the lysosome was viewed as a digestive organelle. In the past fifteen years it has been recast as the cell’s central metabolic signalling hub — the docking site of mTORC1, the transcriptional target of TFEB, and the key point of failure in most major neurodegenerative diseases.
Seven Modules
- M0 — Discovery & Architecture: de Duve 1955 cell fractionation, LAMP1/2 glycocalyx shield, primary/secondary/residual lysosomes, lysosome-related organelles (melanosomes, lytic granules).
- M1 — V-ATPase & Acidification: V1V0rotary structure (~900 kDa), 2:1 H+/ATP stoichiometry, ClC-7 counter-ion, pump-leak balance, pH 4.7 setpoint. Bafilomycin and chloroquine mechanisms.
- M2 — Hydrolases & pKa Engineering: cathepsins (A/B/D/K/L), glycosidases, sulphatases, lipases; the pKa-based fail-safe that inactivates cytosolic cathepsins ~103-fold; saposins, NPC1/NPC2 exporters; LMP and galectin-mediated lysophagy.
- M3 — Delivery Pathways: clathrin-mediated endocytosis, macropinocytosis in Ras-driven cancers, FcγR/complement/PS phagocytosis, Ohsumi 2016 Nobel autophagy genes (ATG1–ATG41+), macro/micro/CMA, selective autophagy receptors.
- M4 — Lysosomal Storage Disorders: Gaucher (GBA), Fabry, Pompe, Niemann-Pick, Tay-Sachs, MPS I-VII; ERT (imiglucerase, agalsidase), SRT (miglustat, eliglustat), gene therapy (Libmeldy for MLD), and the GBA-heterozygous link to Parkinson’s disease.
- M5 — mTORC1 at the Lysosome: David Sabatini’s lab work, Rag GTPases, Ragulator, amino-acid sensors (Sestrin, CASTOR, SAMTOR, SLC38A9), mTORC1 downstream outputs (S6K, 4E-BP1, ULK1, TFEB), rapamycin and rapalogs, mTORC1 in cancer and aging (ITP cohort lifespan data).
- M6 — Lysosome in Neurodegeneration: GBA/Parkinson, progranulin/FTD, C9ORF72 in ALS, TFEB as a therapeutic master switch, ambroxol GBA-PD trials, cerliponase alfa for CLN2 Batten disease.