Intestinal ischemia/reperfusion (I/R) causes epithelial oxidative injury, barrier dysfunction, and apoptotic loss, yet its post-translational basis remains poorly understood. SUMOylation is a reversible post-translational process that modulates protein stability and intracellular signaling under stress. However, the role and mechanism of SENP3, a redox-sensitive deSUMOylase, in intestinal I/R remain unclear. In this study, we examined the contribution of SENP3 to intestinal I/R and its mechanism. SENP3 abundance increased substantially in intestinal tissue of mice subjected to I/R and epithelial cells subjected to hypoxia/reoxygenation (H/R). Moreover, blockade of hydrogen peroxide signaling reduced the H/R-induced increase in SENP3 protein without materially altering its mRNA level, suggesting peroxide-associated redox-dependent regulation primarily at the post-transcriptional level. Functionally, SENP3 knockdown alleviated mucosal injury, reduced epithelial apoptosis, and mitigated remote organ damage. Transcriptomic profiling revealed enrichment of the PI3K-Akt pathway following SENP3 knockdown. Additionally, PDPK1, a critical regulator of this pathway, was identified as a SENP3-interacting protein by immunoprecipitation-mass spectrometry and validated by co-immunoprecipitation. SENP3 promoted PDPK1 deSUMOylation in a catalytically dependent manner, leading to increased K48-linked ubiquitination and proteasomal degradation. Site-directed mutagenesis identified Lys296 as a major SUMOylation site on PDPK1. Consequently, SENP3-mediated PDPK1 destabilization suppressed PI3K-Akt signaling, whereas SENP3 inhibition preserved PDPK1 levels and downstream survival signaling. These findings support a SUMO-ubiquitin switch mechanism whereby SENP3-mediated deSUMOylation facilitates ubiquitin-dependent degradation of PDPK1. Overall, our findings define a SENP3-PDPK1-PI3K-Akt regulatory axis linking oxidative stress to epithelial apoptosis during intestinal I/R and support SENP3 as a candidate target for maintaining barrier integrity and reducing reperfusion-related injury.
Liu et al. (Fri,) studied this question.