GNPAT/USP30 Stabilizes DRP1 Protein to Promote Mitochondrial Fission and Functional Damage in COPD Progression.

Abstract

Our previous study revealed the role of glycerol phosphate O-acyltransferase (GNPAT) in regulating chronic obstructive pulmonary disease (COPD). However, its further mechanisms remained unclear. In this study, COPD models were established by exposing mice to cigarette smoke particulates. H&E staining and immunohistochemistry assays were performed on COPD tissue. A549 cells were stimulated with 5% cigarette smoke extract (CSE) and transfected with GNPAT, ubiquitin-specific protease 30 (USP30), and dynamin-related protein 1 (DRP1) plasmids. Cell viability, cell apoptosis, lactate dehydrogenase (LDH) release, ATP production, and reactive oxygen species (ROS) levels were determined using commercial kits. Quantitative real-time PCR and western blotting were used to evaluate mRNA and protein expression. Mitochondrial morphology was examined by transmission electron microscopy. A co-immunoprecipitation assay determined the binding relationships among GNPAT, USP30, and DRP1. Our results showed that GNPAT and DRP1 were highly expressed in the COPD model mice. CSE promoted mitochondrial fission, mitochondrial dysfunction, and cell apoptosis, which were further enhanced by treatment with a mitochondrial fission inducer (TA9). GNPAT promoted mitochondrial fission, mitochondrial dysfunction, and cell apoptosis by enhancing DPR1 protein stability, which depended on USP30. DRP1 enhanced mitochondrial fission, mitochondrial dysfunction, and cell apoptosis, which were both reversed by GNPAT/USP30 inhibition. Collectively, our present study found that GNPAT recruited USP30 and stabilized DRP1, thereby mediating mitochondrial fission and mitochondrial dysfunction that contributed to cell apoptosis in COPD. This study suggests a promising therapeutic biomarker for COPD.