Fat droplet autophagy
Lysosomal lipid droplet degradation
Also searched as Lysosomal lipid droplet degradation.
You want it available, because it works when the main route does not. It is a genuinely different mechanism: droplets are engulfed and digested by acid lipases in lysosomes rather than cut on the surface by the usual enzymes. The two routes are sequential, not interchangeable — only small droplets can be engulfed, while large ones must first be trimmed by ordinary lipolysis. And the direction of control is simple: nutrient abundance shuts it down, energy deprivation opens it, and it declines with age.
In depth
Fat broken down inside lysosomes rather than by lipases — a separate, parallel way out.
What drives it
Fasting response increases it.
'Generally, nutrient abundance inhibits lipophagy, while energy deprivation promotes it' (doi 10.3389/fphys.2022.826314), induced by the metabolic kinases mTORC1 and AMPK. Note: this is a lane where AMPK is an activator — the same kinase that brakes the lipase route opens this one. doi 10.3389/fphys.2022.826314
Insulin sensitivity reduces it.
'nutrient abundance inhibits lipophagy' and 'HFD feeding suppresses autophagy in mouse liver' (doi 10.3389/fphys.2022.826314). And an aging note worth keeping: 'the age-dependent decrease in autophagy could underline the basis for the metabolic syndrome of aging.'. doi 10.3389/fphys.2022.826314
Growth complex reduces it.
The same kinase, the opposite sign, on a different route. 'Under conditions of nutrient deprivation, induced by the major metabolic kinases mTORC1 and AMPK, lipid droplets and autophagic machinery associate to form autophagic vacuoles' (doi 10.3389/fphys.2022.826314) — nutrient deprivation relieves mTORC1 and opens lipophagy, while nutrient abundance suppresses it. Drawn inhibitory because the active, fed-state kinase is what holds this route shut. doi 10.3389/fphys.2022.826314
Lysosomal lipase increases it.
'lysosomal acid lipases are ultimately responsible for the acid hydrolysis of the LD-stored neutral lipids and subsequent release of free fatty acids' (doi 10.3389/fphys.2022.826314). The endpoint enzyme of the alternative route. doi 10.3389/fphys.2022.826314
What it drives
It increases Releases stored fat.
A genuinely separate route out. 'autophagy-based lipophagy offers an alternative mechanism for the control of fat mobilization and breakdown... Lipid droplets and autophagic machinery associate to form autophagic vacuoles and subsequently autophagy promotes lipid breakdown by releasing engulfed LDs to lysosomes for degradation. Lysosomal acid lipases are ultimately responsible for the acid hydrolysis' (doi 10.3389/fphys.2022.826314). The two are sequential, not interchangeable: 'only tiny or smaller lipid droplets can be directly targeted by lipophagy, whereas larger lipid droplets seem to be preferentially broken down into smaller ones via lipolysis.'. doi 10.3389/fphys.2022.826314
It increases Lysosomal lipase.
'autophagy promotes lipid breakdown by releasing engulfed LDs to lysosomes for degradation' (doi 10.3389/fphys.2022.826314) — the route delivers the substrate to the enzyme. doi 10.3389/fphys.2022.826314
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.