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Updated: Sep 9, 2026

Evaluation of LC3-II Release via Extracellular Vesicles in Relation to the Accumulation of Intracellular LC3-positive Vesicles
Published on: October 18, 2024
USP26 Promotes Autophagosome-Lysosome Fusion to Improve Mitochondrial Function in the Repair of Gut Barrier Damage by
Weiming Li1, Qinghua Zou2, Jiaping Wang3
1Department of Gastrointestinal Surgery, The Second Affiliated Hospital of Kunming Medical University, Kunming, China.
Aims:
Intestinal mucosal barrier injury is a major consequence of intestinal ischemia-reperfusion (II/R) and contributes to poor clinical outcomes. While mitophagy sustains mitochondrial homeostasis, how impaired autophagic flux disrupts intestinal barrier function remains unclear. We investigated the role of the deubiquitinase ubiquitin-specific protease 26 (USP26) and its downstream target syntaxin 17 (STX17) in regulating mitophagy and intestinal barrier repair.
Methods:
II/R mouse models and oxygen-glucose deprivation/reperfusion (OGD/R)-treated Caco-2 cells were used to evaluate intestinal barrier integrity. Functional manipulation, autophagy blockade, Co-IP, ubiquitination assays, Seahorse metabolic detection, and in vivo rescue assays were performed to dissect the USP26-STX17 regulatory axis.
Results:
USP26 was markedly downregulated in II/R intestinal tissues and OGD/R Caco-2 cells, coinciding with impaired autophagy, mitochondrial dysfunction, and intestinal barrier disruption. USP26 overexpression preserved intestinal architecture, reduced permeability and apoptosis, and restored expression of the tight-junction proteins. Functionally, USP26 enhanced autophagic flux and mitophagy, as evidenced by increased LC3-II/LC3-I ratios, reduced p62 accumulation, elevated PINK1/Parkin signaling, improved adenosine triphosphate production, restored mitochondrial membrane potential, and normalized cellular bioenergetics; autophagy inhibition attenuated these protective phenotypes. Mechanistically, USP26 bound STX17 and stabilized it via deubiquitination. STX17 knockdown impaired autophagosome-lysosome fusion and largely abolished USP26-mediated mitochondrial and intestinal barrier protection in vitro and in vivo.
Conclusions:
This study identifies the USP26-STX17 axis as a previously unrecognized regulator of autophagosome-lysosome fusion and mitophagy in II/R injury. By restoring mitochondrial quality control and epithelial barrier integrity, USP26 emerges as a promising therapeutic target for the prevention and treatment of gut barrier dysfunction associated with critical illness. Antioxid. Redox Signal. 00, 000-000.
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