GSK-3-TSC axis governs lysosomal acidification through autophagy and endocytic pathways

Limor Avrahami, Rom Paz, Kristina Dominko, Silva Hecimovic, Cecilia Bucci, Hagit Eldar-Finkelman

Research output: Contribution to journalArticlepeer-review


Impaired lysosomal activity, which results in defective protein processing, waste accumulation, and protein aggregation, is implicated in a number of disease pathologies. Acidification of lysosomes is a crucial process required for lysosome function. Previously we showed that inhibition of glycogen synthase kinase-3 (GSK-3) enhanced lysosomal acidification in both normal and pathological conditions. However, how GSK-3 integrates into the lysosome networking is unknown. Here we show that inhibition of mTORC1 and increased autophagic activity are downstream to GSK-3 inhibition and contribute to lysosomal acidification. Strikingly, lysosomal acidification is also restored by GSK-3 inhibition in the absence of functional autophagy, and, independently of mTORC1. This is facilitated by increased endocytic traffic: We show that GSK-3 inhibition enhanced material internalization, increased recruitment of active Rab5 into endosomes, and increased Rab7/RILP clustering into lysosomes, all processes required for late endosome maturation. Consistently, in cells defective in endocytic traffic caused by either constitutively active Rab5, or, deletion of the Niemann-Pick C1 protein, GSK-3 inhibition could not restore lysosomal acidification. Finally we found that the tuberous sclerosis complex, TSC, is required for lysosomal acidification and is activated by GSK-3 inhibition. Thus, the GSK-3/TSC axis regulates lysosomal acidification via both the autophagic and endocytic pathways. Our study provides new insights into the therapeutic potential of GSK-3 inhibitors in treating pathological conditions associated with impaired cellular clearance.

Original languageEnglish
Article number109597
JournalCellular Signalling
StatePublished - Jul 2020


  • Acidification
  • Autophagy
  • Endocytosis
  • GSK-3
  • GSK-3 inhibitors
  • L803-mts
  • Lysosomes
  • Rab5
  • Rab7
  • TSC
  • mTOR

All Science Journal Classification (ASJC) codes

  • Cell Biology


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