Chronic mTORC1-ULK1 signaling blocks autophagy initiation in irradiated pericytes

Hypothesis 1: Radiation-induced pericyte senescence is driven by a late-stage autophagy defect at the lysosome acidification and TFEB-recovery step, not by loss of autophagosome formation. Damaged lysosomes would trap LC3-positive cargo, amplify ROS, and sustain SASP signaling. Test: lysosomal pH, cathepsin maturation, TFEB nuclear translocation, and tandem LC3 reporters after irradiation.

Hypothesis 2: The dominant lesion is defective mitophagy through the PINK1-PRKN axis, causing persistence of damaged mitochondria that lock pericytes into a senescent, inflammatory state. Test: mitochondria

Hypothesis 1 fits many senescence phenotypes, but accumulation of LC3 or SQSTM1 alone cannot distinguish lysosome failure from overproduction of autophagosomes. Without flux measurements and direct pH or cathepsin assays, this interpretation is too coarse.

Hypothesis 2 is compelling because mitochondria are plausible radiation-sensitive organelles, yet mitophagy collapse may be downstream of a broader lysosomal problem rather than the initiating lesion. The falsification test is whether general lysosome rescue normalizes mitochondrial quality control more effectively than PINK1-pathway manipu

The best development plan is a temporal map of autophagy after irradiation in primary human brain pericytes: 6 h, 24 h, 72 h, and senescence endpoints. That can separate initiation defects from clearance defects and reveal whether mitophagy failure is a primary driver or a secondary consequence.

Lysosome and mitophagy programs both offer tractable intervention hooks. If acidification failure dominates, TFEB activators or lysosome-repair strategies become attractive; if mitophagy dominates, mitochondrial QC enhancers are the cleaner path. For translational relevance, the most important bridge

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