SENP3-mediated deSUMOylation of PINK1 suppresses mitophagy and aggravates lipopolysaccharide-induced acute lung injury

Abstract Background Mitochondrial dysfunction triggers excessive reactive oxygen species (ROS) accumulation, which greatly exacerbates acute lung injury (ALI). Mitophagy, a cellular mechanism for maintaining mitochondrial homeostasis, is crucial to the progression of ALI. SENP3 is a redox-sensitive SUMO2/3 protease that is pivotal in the regulation of mitochondrial function. However, the relationship between SENP3 and mitophagy in ALI remains unclear. Methods Bronchoalveolar lavage fluid (BALF) was obtained from 20 participants (14 patients with infection-related ALI and 6 healthy controls) to explore the clinical correlation between SENP3 levels and ALI severity. Mice with conditional knockout of Senp3 in alveolar type II (AT2) cells were intratracheally injected with LPS to assess the role of SENP3 in ALI pathogenesis. Mice with AAV9 vectors carrying the SUMO3-PINK1 fusion protein (AAV-SUMO3-PINK1) were exposed to LPS to verify the effect of PINK1 SUMOylation in ALI in vivo. SUMOylation was detected using the NI-NTA assay. Immunofluorescence, transmission electron microscopy (TEM) and Western blotting were used to assess mitophagy in this study. Results Elevated SENP3 levels in BALF were positively correlated with ALI severity. LPS-induced ALI was markedly alleviated in Senp3 conditional knockout mice, and mitophagy was accelerated following SENP3 knockdown. Mechanistically, PINK1 was conjugated with SUMO3 by the E3 ligase PIAS4 predominantly at residue K114 and deSUMOylated by SENP3. DeSUMOylation of PINK1 markedly reduced ubiquitin phosphorylation (p-Ser65-Ub), leading to impaired mitophagy. Mice treated with AAV-SUMO3-PINK1 exhibited superior protection against LPS-induced injury compared to mice receiving AAV-control or AAV-PINK1. Conclusions SENP3 deficiency alleviates LPS-induced ALI by promoting mitophagy. These findings identify SUMOylation as a previously undescribed post-translational modification of PINK1 and establish a novel regulatory role for SENP3 in ALI through the modulation of mitophagy. This work provides insights into therapeutic strategies targeting post-translational modifications of mitophagy regulators for ALI treatment.