Alzheimer's disease (AD) is the major form of dementia in the elderly and is closely related to the toxic effects of microglia sustained activation. In AD, sustained microglial activation triggers impaired synaptic pruning, neuroinflammation, neurotoxicity, and cognitive deficits. Accumulating evidence has demonstrated that aberrant expression of deubiquitinating enzymes is associated with regulating microglia function. Here, we use RNA sequencing to identify a deubiquitinase YOD1 as a regulator of microglial function and AD pathology. Further study showed that YOD1 knockout significantly improved the migration, phagocytosis, and inflammatory response of microglia, thereby improving the cognitive impairment of AD model mice. Through LC-MS/MS analysis combined with Co-IP, we found that Myosin heavy chain 9 (MYH9), a key regulator maintaining microglia homeostasis, is an interacting protein of YOD1. Mechanistically, YOD1 binds to MYH9 and maintains its stability by removing the K48 ubiquitin chain from MYH9, thereby mediating the microglia polarization signaling pathway to mediate microglia homeostasis. Taken together, our study reveals a specific role of microglial YOD1 in mediating microglia homeostasis and AD pathology, which provides a potential strategy for targeting microglia to treat AD.

Long-term hypertension causes excessive vascular remodeling and leads to adverse cardiovascular events. Balance of ubiquitination and deubiquitination has been linked to several chronic conditions, including pathological vascular remodeling. In this study, we discovered that the expression of ubiquitin-specific protease 25 (USP25) is significantly up-regulated in angiotensin II (Ang II)-challenged mouse aorta. Knockout of Usp25 augments Ang II-induced vascular injury such as fibrosis and endothelial to mesenchymal transition (EndMT). Mechanistically, we found that USP25 interacts directly with Forkhead box O3 (FOXO3) and removes the K63-linked ubiquitin chain on the K258 site of FOXO3. We also showed that this USP25-mediated deubiquitination of FOXO3 increases its binding to light chain 3 beta isoform and autophagosomic-lysosomal degradation of FOXO3. In addition, we further validated the biological function of USP25 by overexpressing USP25 in the mouse aorta with AAV9 vectors. Our studies identified FOXO3 as a new substrate of USP25 and showed that USP25 may be a potential therapeutic target for excessive vascular remodeling-associated diseases.

Doxorubicin (Dox) is an anthracycline drug widely applied in various malignancies. However, the fatal cardiotoxicity induced by Dox limits its clinical application. Post-transcriptional protein modification via ubiquitination/deubiquitination in cardiomyocytes mediates the pathophysiological process in Dox-induced cardiotoxicity (DIC). In this study, we aimed to clarify the regulatory role and mechanism of a deubiquitinating enzyme, ubiquitin-specific peptidase 13 (USP13), in DIC. RNA-seq analysis and experimental examinations identified that cardiomyocyte-derived USP13 positively correlated with DIC. Mice with cardiac-specific deletion of USP13 were subjected to Dox modeling. Adeno-associated virus serotype 9 (AAV9) carrying cTNT promoter was constructed to overexpress USP13 in mouse heart tissues. Cardiomyocyte-specific knockout of USP13 exacerbated DIC, while its overexpression mitigated DIC in mice. Mechanistically, USP13 deubiquitinates the stimulator of interferon genes (STING) and promotes the autolysosome-related degradation of STING, subsequently alleviating cardiomyocyte inflammation and death. Our study suggests that USP13 serves a cardioprotective role in DIC and indicates USP13 as a potential therapeutic target for DIC treatment.