Stress-Specific Autophagy Receptor Hierarchies Become Chronically Locked in Aging, Creating Pathological Organelle Accumulation Patterns

Selective autophagy employs a dynamic hierarchy of receptors (p62, NBR1, OPTN, NDP52) whose dominance shifts based on metabolic state and stress type [1][2]. Recent evidence shows inflammation induces early upregulation of ER-phagy receptors (OPTN, SEC62), prioritizing ER turnover at the expense of other pathways [3]. I propose this stress-induced receptor reprioritization is a transient, adaptive program that becomes chronically locked during aging, leading to pathological organelle accumulation patterns rather than global autophagy failure.

The mechanistic core: Stress-specific signaling creates a transcriptional and post-translational "receptor imprint" that persists after stress resolution. Acute inflammation activates NF-κB and ATF4 pathways, which upregulate OPTN/SEC62 [3]. In young cells, resolution of inflammation allows mTORC1/AMPK rebalancing and receptor profile reset. In aging, cumulative stressors (chronic inflammation, ER stress, metabolic shifts) may create overlapping, persistent signaling that locks cells into a dominant ER-phagy program. This comes at the direct expense of mitophagy and pexophagy receptors, whose basal expression declines through competitive autophagy receptor network dynamics [1].

Testable prediction: Aged neurons or hepatocytes will show:

1. Persistently elevated OPTN/SEC62:ER-phagy flux ratios even after resolution of inflammatory stimuli
2. Correspondingly reduced p62/NBR1-mediated mitochondrial and peroxisomal clearance
3. This pattern will be reversed by transient OPTN knockdown followed by recovery period, not by global autophagy induction

Falsifiable experiment: Use doxycycline-inducible OPTN overexpression in young neurons to mimic the "locked" ER-phagy state, then assess time-course of recovery after OPTN shutdown. If the hypothesis is correct, young cells will rapidly rebalance receptor profiles, while aged cells (or cells with artificially induced senescence markers) will show prolonged OPTN dominance and impaired mitophagy recovery.

The hierarchy collapse isn't due to lysosomal overwhelm per se, but to maladaptive receptor prioritization creating cargo traffic jams—damaged mitochondria accumulate not because the system is globally broken, but because they're perpetually deprioritized in the autophagy queue [4]. This reframes age-related proteotoxicity as a routing error rather than a capacity failure.