Curcumin controls lysosomal acidification and exocytosis to ameliorate lysosomal cholesterol accumulation in Niemann–Pick type C disease

Abstract Background and Purpose Niemann–Pick type C disease (NPCD) is a rare and fatal lysosomal storage disorder. There are limited therapies for NPCD, although multiple small‐molecule compounds have shown therapeutic potential for NPCD. Curcumin (CUR), a polyphenolic compound enriched in turmeric, has cholesterol‐lowering effects via regulating intestinal cholesterol absorption and liver cholesterol synthesis. CUR normalises sphingolipid trafficking and stimulates exosome/microvesicle release, increases cytosolic Ca 2+ levels, and enhances lysosomal activation via mTOR suppression and TFEB activation. How CUR specifically targets lysosomal cholesterol has not been fully clarified. Experimental Approach Effects of curcumin on lysosomal cholesterol accumulation were evaluated in NPC1 cell models. Filipin staining, immunofluorescence, surface LAMP1 and NAGase activity and Cathepsin B activity were investigated to evaluate lysosomal cholesterol, TFEB translocation, lysosomal exocytosis and hydrolytic activity. Lysosomal acidification was determined by Lysotracker Red, Oregon Green, and sfGFP/mCherry transfection. CRISPR/Cas9 and siRNA interference were used to investigate the role of TFEB/TFE3 and TRPML1 in curcumin‐induced cholesterol reduction. Key Results CUR alleviates lysosomal cholesterol accumulation in NPC1 cells in a TFEB‐ and TFE3‐dependent manner. CUR enhanced lysosomal acidity and promoted calcium‐dependent lysosomal exocytosis, which contributed to CUR‐mediated lysosomal cholesterol clearance. The combination of CUR with specific agonists (ML‐SAs) of MCOLN1/TRPML1, a lysosomal cation channel required for lysosomal exocytosis, improved lysosomal cholesterol clearance. Conclusion and Implications CUR reduces lysosomal cholesterol accumulation in NPC1 cells by activating TFEB/TFE3 pathways and promoting Ca 2+ ‐ and TRPML1‐dependent lysosomal exocytosis. These findings support curcumin and its analogues as potential therapeutics for NPCD and other diseases of lysosomal storage.