# Mechanistic Hypotheses: Shared Autophagy Induction by Structurally Diverse Disaccharides
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## Hypothesis 1: Lysosomal Accumulation-Induced V-ATPase Inhibition
**Title:** Osmotic trapping of non-hydrolyzed disaccharides in acidic lysosomes causes V-ATPase-dependent TFEB activation
**Mechanism:** Trehalase-resistant analogs and other disaccharides accumulate within lysosomes because they escape hydrolytic degradation. The resulting osmotic gradient draws water into lysosomes, disrupting their membrane integrity and inhibiting V-ATPase proton pumps. Reduced lysosomal acidification prevents mTORC1 recruitment to lysosomal surfaces, releasing TFEB to translocate to the nucleus.
**Target:** V-ATPase (ATP6V0C, ATP6V1 subunits)
**Supporting Evidence:**
- Trehalose inhibits V-ATPase activity (PMID: 24728189)
- TFEB nuclear translocation requires mTORC1 dissociation from lysosomes (PMID: 21543718)
- Lysosomal swelling observed with trehalose treatment (PMID: 28334960)
- Lactulose and melibiose are similarly resistant to lysosomal hydrolysis
**Predicted Experiment:** Use LysoSensor Green/FM 1-43 to measure lysosomal pH and membrane integrity after 6h treatment with trehalose, lactulose, or melibiose. Perform co-immunoprecipitation of mTOR with Rag GTPases. Compare with bafilomycin A1 (V-ATPase inhibitor) as positive control.
**Confidence:** 0.72
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## Hypothesis 2: cAMP/PKA-Dependent Transcription Factor Activation
**Title:** Disaccharide-induced nutrient stress activates PKA/CREB signaling independently of mTOR, driving TFEB expression
**Mechanism:** Structurally diverse disaccharides may trigger a general "nutrient stress" response via unidentified membrane sensors, elevating intracellular cAMP and activating PKA. PKA phosphorylates and activates transcription factors (CREB, CRTC2) that drive expression of autophagy and lysosomal genes, while simultaneously promoting nuclear import of TFEB via CRTC2-mediated coactivation.
**Target:** PRKACA (catalytic subunit of PKA), CREB1, CRTC2
**Supporting Evidence:**
- cAMP-elevating agents induce autophagy (PMID: 20085788)
- CRTC2 promotes TFEB transcriptional activity (PMID: 27999501)
- Trehalose increases intracellular cAMP in yeast (PMID: 17607311)
- Lactulose fermentation produces SCFAs that activate GPCRs (PMID: 25109855)
**Predicted Experiment:** Measure intracellular cAMP levels using ELISA after 2-4h disaccharide treatment. Use H89 (PKA inhibitor) and KT5720 to test whether PKA blockade prevents TFEB nuclear translocation and autophagy induction. Perform RNA-seq on nuclei isolated from treated cells.