USP48 protects against myocardial ischemia-reperfusion injury by stabilizing and upregulating CNN1 in type 1 diabetes mice.

Ubiquitin-specific protease 48 (USP48) plays an important role in the regulation of DNA repair and immune signaling in health and diseases. Nonetheless, its implication in the development of diabetes-accelerated myocardial ischemia/reperfusion (I/R) injury (MI/RI) has yet to be clarified. Diabetic mice were constructed by streptozotocin (STZ) injection, and MI/RI was then induced by coronary artery occlusion and reperfusion. H9c2 cells were exposed to high glucose (HG) for 24 h, followed by hypoxia/reoxygenation (H/R) for 4 and 2 h, respectively. USP48 protein and mRNA levels were downregulated in MI/RI mice or H/R-exposed cardiomyocytes, but were unexpectedly upregulated in diabetic mice following MI/RI and H9c2 cells exposed to HG and H/R. Cardiac-specific deficiency of USP48 worsened cardiac dysfunction, increased post-ischemic infarction size, promoted mitochondrial damage in myocardial cells, accelerated cardiomyocyte inflammation, oxidative stress, and apoptosis in diabetic mice. Conversely, such pathological conditions were ameliorated by cardiac-specific overexpression of USP48. Proteomics and experimental validation showed that USP48 stabilized and upregulated calponin 1 (CNN1) to confer cardioprotection, since silencing CNN1 minimized the benefits of USP48 in diabetes-aggravated cardiomyocyte injury. RNA sequencing and experimental data demonstrated that the USP48/CNN1 axis inhibited the release of CXC motif chemokine ligand 1 (CXCL1) and CXCL2 through inactivating the ERK1/2 pathway. Eventually, blockade of CXCL1/2 with specific antibodies protected against diabetes-exacerbated MI/RI, akin to USP48 overexpression. Together, these results highlight USP48 as a potential therapeutic target for managing diabetes-aggravated MI/RI by regulating the CNN1/ERK1/2/CXCL1/2 signaling pathway.