Autophagic Flux

Classification

Category: Process (dynamic, not a single molecule)

Aliases: Autophagy flux, Macroautophagy flux

Relationship to mTOR complexes: Downstream of mTORC1 (via ULK1, TFEB) and mTORC2-adjacent pathway context — see mTORC1 vs mTORC2 for the full complex-level map.

Summary

CORE EDITORIAL POINT: autophagic flux is the RATE of the complete autophagy process -- autophagosome formation, cargo sequestration, fusion with lysosomes, and degradation/turnover of the cargo -- measured over time. It is a PROCESS, not a static blood or tissue biomarker level. A static, single-timepoint measurement of LC3-II or p62 does NOT equal flux, because both proteins can accumulate either from increased autophagosome formation OR from decreased downstream lysosomal clearance -- the two scenarios look identical on a single static snapshot but mean opposite things biologically.

• ULK1 activation (de-repressed when mTORC1 activity falls) initiates autophagosome formation -- see /ulk1
• TFEB nuclear translocation (also de-repressed when mTORC1 activity falls) upregulates lysosomal biogenesis genes needed for downstream clearance -- see /tfeb

• Degradation and turnover of sequestered cellular cargo (proteins, organelles) via the lysosome

• PROPER FLUX MEASUREMENT requires a lysosomal-turnover assay design (e.g. comparing LC3-II/p62 levels with and without a lysosomal inhibitor such as bafilomycin or chloroquine) to distinguish increased formation from decreased clearance -- a single static measurement cannot do this.
• This dataset's assay-reference table lists LC3-II, p62/SQSTM1, ULK1 phosphorylation state, and TFEB localization as STATIC markers, and explicitly flags that none of them alone constitutes a flux measurement.
• 'Activates autophagy' claims about any intervention on this site (rapamycin, spermidine, caloric restriction, exercise) should be read as referring to reported STATIC marker changes or animal-model findings, not to a verified body-wide flux measurement in humans, unless the specific study record states a flux assay was used.

Source tier

Tier 2 · Biological synthesis (author-cluster reviews, not primary trial data) Reference synthesis attributed in the brief to the Saxton & Sabatini; Laplante & Sabatini; and Liu & Sabatini mTOR review literature (author-cluster attribution, tier 2, brief §4, 'autofagisk flux' nuance). Exact article-level PMID/DOI not supplied in the sourcing brief and is not fabricated here.