The function of ubiquitin-specific protease 31 in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is the most serious type of stroke. High level of thrombin is found in the ICH. Ubiquitin-specific protease (USP) 31, a member of deubiquitinating enzymes family, has been found to negatively regulate the NF-kappa B pathway. However, the function of USP31 in ICH remains largely unknown. In the present study, the mRNA and protein expression levels of USP31 were measured by real-time PCR and western blot. Flow cytometry was used to measure cell apoptosis and the level of reactive oxygen species (ROS). In the current study, we found the mRNA level of USP31 was decreased in peripheral blood mononuclear cells (PBMCs) from the patients with ICH. Thrombin stimulated cell apoptosis, and increased the ROS level, the productions of interleukin-113 (IL-113), tumor necrosis factor-alpha (TNF-alpha), and monocyte chemoattractant protein-1 (MCP-1), but it decreased the expression level of USP31 in BV-2 cells. In agreement, USP31 overexpressing could alleviate these effects caused by thrombin. USP31 partially reversed the thrombin induced increase of nuclear factor kappa B (NF-kappa B) localization. Further, NF kappa B inhibitor could alleviate the effects induced by USP31 knockdown. In addition, USP31 decreased the ubiquitination level of I kappa B alpha, which might contribute to the depression of NF-kappa B activation. In conclusions, USP31 played a role in the ICH might via regulating NF-kappa B signaling pathway.