# O-GlcNAcylation of YAP1 promotes lung transplant ischemia-reperfusion injury via binding to HIF1α transcription factor and activating autophagy and mitophagy

## TL;DR

This study shows that O-GlcNAcylation of YAP1 worsens lung transplant injury by boosting autophagy and mitophagy through HIF1α interaction.

## Contribution

The novel finding is that O-GlcNAcylation of YAP1 promotes lung transplant injury via HIF1α binding and autophagy activation.

## Key findings

- YAP1 O-GlcNAcylation enhances HIF1α binding and activates autophagy and mitophagy during lung injury.
- Knockdown of YAP1 or OGT reduces autophagy and tissue damage in lung transplant ischemia-reperfusion.
- O-GlcNAcylation of YAP1 is a key driver of lung epithelial cell stress and injury in transplantation.

## Abstract

Lung transplant ischemia-reperfusion injury poses a significant challenge in transplantation medicine, often causing severe complications and poor patient outcomes. Our study focused on the role of O-GlcNAcylation of Yes-associated protein 1 (YAP1) in exacerbating this injury by regulating autophagy and mitochondrial autophagy pathways. We found that hypoxia-reoxygenation robustly activated the Hippo-YAP1 signaling pathway, leading to increased damage in lung epithelial cells. Concurrently, autophagy and mitochondrial autophagy levels were significantly upregulated, indicating cellular stress responses. During actual lung transplantation, ischemia-reperfusion resulted in a marked increase in autophagy and mitochondrial autophagy levels, accompanied by elevated tissue damage. Notably, YAP1 played a crucial role in orchestrating these processes, as its knockdown reduced autophagy and mitochondrial autophagy levels under both hypoxia-reoxygenation and ischemia-reperfusion conditions. We further elucidated that OGT-mediated O-GlcNAc modification of YAP1 enhanced its interaction with HIF1α, activating downstream hypoxia-responsive molecules. Knockdown of the key enzyme OGT significantly mitigated autophagy, mitophagy, and associated damage in lung epithelial cells and transplant tissues subjected to hypoxia-reoxygenation and ischemia-reperfusion. These findings reveal the intricate interplay between O-GlcNAcylation of YAP1, HIF1α binding, autophagy activation, and mitochondrial autophagy in driving lung transplant ischemia-reperfusion injury, suggesting potential therapeutic targets for ameliorating its detrimental effects.