Identification of OTUD7a downregulation and global ubiquitination remodeling in a murine asthma model.

Airway epithelial dysfunction is a hallmark of asthma, contributing to chronic inflammation and structural remodeling. Recent research suggests the role of post-translational modifications in regulating epithelial immune responses. However, the role of specific deubiquitinating enzymes (DUBs) remains unclear. In this study, we identified OTU deubiquitinase 7a (OTUD7a) as a gene that is significantly downregulated in a murine model of allergic asthma. Transcriptomic analysis of two independent datasets (GSE71822 and GSE9383) consistently revealed the suppression of OTUD7a in asthmatic lungs. Furthermore, immunofluorescence analysis suggested that OTUD7a was detected in CC10-positive bronchiolar epithelial cells, non-ciliated epithelial cells known for their anti-inflammatory functions. To explore the molecular associations of OTUD7a, we established a club cell line overexpressing Flag-tagged OTUD7a and performed co-immunoprecipitation-mass spectrometry (Co-IP/MS). We identified 1135 candidate interacting proteins. In parallel, LC-MS/MS-based ubiquitinome profiling in ovalbumin (OVA)-induced asthmatic lungs revealed widespread changes in protein ubiquitination, with more than 3000 differentially modified ubiquitination sites. These changes were enriched in pathways associated with immune signaling, cytoskeletal dynamics, and epithelial barrier function. Collectively, our findings suggest that OTUD7a, as a DUB detected in CC10-positive bronchiolar epithelial cells, is markedly decreased in asthma and they present a comprehensive landscape of ubiquitination changes in allergic airway inflammation. Therefore, our study offers new insight into post-translational regulation in the pathogenesis of asthma.