AMPK activation promotes lipid droplet dispersion on detyrosinated microtubules to increase mitochondrial fatty acid oxidation

TLDR

Lipid droplets supply fatty acids for energy and move along microtubules, but how their motion facilitates organelle interactions remains unclear. Starvation‑activated AMPK boosts lipid‑droplet motility, reorganizes detyrosinated microtubules, and stimulates mitochondria, coordinating their redistribution. Under nutrient deprivation, lipid droplets and mitochondria disperse onto detyrosinated microtubules, enhancing peripheral interactions that deliver fatty acids for β‑oxidation and demonstrating a network that links cellular energy status to microtubule dynamics.

Abstract

Abstract Lipid droplets (LDs) are intracellular organelles that provide fatty acids (FAs) to cellular processes including synthesis of membranes and production of metabolic energy. While known to move bidirectionally along microtubules (MTs), the role of LD motion and whether it facilitates interaction with other organelles are unclear. Here we show that during nutrient starvation, LDs and mitochondria relocate on detyrosinated MT from the cell centre to adopt a dispersed distribution. In the cell periphery, LD–mitochondria interactions increase and LDs efficiently supply FAs for mitochondrial beta-oxidation. This cellular adaptation requires the activation of the energy sensor AMPK, which in response to starvation simultaneously increases LD motion, reorganizes the network of detyrosinated MTs and activates mitochondria. In conclusion, we describe the existence of a specialized cellular network connecting the cellular energetic status and MT dynamics to coordinate the functioning of LDs and mitochondria during nutrient scarcity.