Targeting PBK with small-molecule 1-O-acetyl-4R,6S-britannilactone for the treatment of neuroinflammation

Neuroinflammation is a complex immunological phenomenon characterized by a dysregulated inflammatory response in the central nervous system (CNS) that can be triggered by various pathological injuries, such as toxins, which are involved in Parkinson's and Alzheimer's diseases (PD and AD), therefore, suppressing neuroinflammation serves as an effective treatment for CNS diseases. Herein, we found that natural soluble epoxide hydrolase (sEH) inhibitor 1-O-acetyl-4R,6S-britannilactone (AB) regulated mitogen-activated protein kinase (MAPK) and AMP-activated protein kinase (AMPK) pathways to suppress the microglial activation by regulating inflammation and autophagy in vitro and in vivo, contributing to the improvement of lipopolysaccharide (LPS)-mediated neuroinflammation. Protein microarray analysis indicated that AB could selectively target PDZ binding kinase (PBK) through covalently binding to C70, exhibiting a dissociation constant (Kd) of 0.62 μM, which was corroborated by subsequent chemical biology experiments. We gained a deeper understanding of the mechanistic by which AB interfered PBK function, specifically by disrupting its interaction with tumor necrosis factor alpha-induced protein-8 like-2 (TIPE2), blocking the serine 3 (S3) phosphorylation-mediated ubiquitylation and degradation of TIPE2. Additionally, our study revealed that PBK genetic deletion alleviated the course of LPS-mediated neuroinflammation in vitro and in vivo, and AB did not exhibit any extra effects in LPS-mediated PBK^-/- mice. These findings first offered broader prospects for treating neuroinflammation by targeting PBK to repress inflammation and activate autophagy, suggesting that AB had the potential to serve as a direct inhibitor in the PBK-TIPE2 interaction.