USP25 regulates atherosclerosis by restricting RIPK1-mediated inflammatory responses

Background Atherosclerosis is a common vascular disease that poses a serious threat to global health. However, the mechanism underlying the pathogenesis and progression of atherosclerosis remains elusive. Methods We analysed the expression of deubiquitinating enzymes in human atherosclerotic lesions and found that USP25 was significantly downregulated. The role of USP25 in atherosclerosis was validated in mouse models with an ApoE −/− background. The protein substrates of USP25 were identified by mass spectrometry. Various biochemical methods were adopted to study the role of USP25 in signal transduction. Findings USP25 was predominantly expressed in macrophages in atherosclerotic lesions, and ablation of macrophagic USP25 significantly exacerbated atherosclerosis in ApoE −/− mice accompanied by increased lipid deposition, macrophage infiltration, and vascular inflammation. Upon stimulation with ox-LDL or TNF-α, USP25 inhibited inflammatory responses in macrophages by restricting the NF-κB pathway. Mass spectrometry analysis identified RIPK1 as a USP25 substrate. Mechanistically, USP25 physically interacted with RIPK1 and removed K63 ubiquitin chains from RIPK1 via the C178 active site, thereby attenuating RIPK1-mediated signal transduction. Interpretation This study elucidated the function and molecular mechanism of USP25 in atherosclerosis, identifying USP25 as a beneficial regulator for this disease. Funding This work was supported by the Natural Science Foundation of Zhejiang Province (LZ24H090003 to X.W. and LTGY23H090001 to W.W.), the National Natural Science Foundation of China (82150710557 and 82293642 to W.S.; 81971143 to X.W., and 82271347 to G.W.), and Wenzhou Municipal Science and Technology Bureau (Y2021094 to J.H.).