# PTG‐Dependent Glycogen Metabolic Dysfunction Drives Impaired Adipose Browning: A Novel Mechanism Linking PM2.5 to Metabolic Disorders

## TL;DR

PM2.5 exposure disrupts fat tissue browning by affecting glycogen metabolism, leading to metabolic disorders.

## Contribution

This study identifies a new mechanism linking PM2.5 to metabolic dysfunction via the ADRB3-PTG-VEGFB axis.

## Key findings

- PM2.5 exposure inhibits iWAT browning by downregulating PTG and disrupting glycogen homeostasis.
- PTG overexpression reverses PM2.5-induced metabolic impairment by restoring glycogen metabolism and mitochondrial function.
- The ADRB3-PTG-VEGFB axis is central to PM2.5-induced metabolic dysfunction.

## Abstract

Fine particulate matter (PM2.5) contributes to metabolic dysfunction, but its effects on adipose tissue browning remain unclear. Here, we showed that PM2.5 exposure inhibited inguinal white adipose tissue (iWAT) browning by downregulating protein targeting to glycogen (PTG), disrupting glycogen homeostasis. PTG overexpression in iWAT restored glycogen metabolism, thermogenesis, and mitochondrial function, reversing PM2.5‐induced impairment in iWAT browning and metabolic disorders. Mechanistically, PTG negatively regulated vascular endothelial growth factor B (VEGFB), and VEGFB knockdown rescued browning. Activation of β3‐adrenergic receptor (ADRB3) mitigated PM2.5’s effects by restoring PTG and normalizing VEGFB, defining the ADRB3‐PTG‐VEGFB axis as central to PM2.5‐induced metabolic dysfunction. Our findings identify adipose glycogen metabolism as a target for countering environmental metabolic disruption.

This study provides the first evidence that PM2.5 impairs iWAT browning via PTG‐mediated glycogen metabolism disruption, which is initiated by ADRB3 inhibition and subsequently triggers VEGFB upregulation. It thereby delineates the ADRB3‐PTG‐VEGFB axis as central to PM2.5‐induced metabolic dysfunction and identifies adipose glycogen metabolism as a novel therapeutic target against environmental metabolic disruption.