Fine tuning of the inflammaotry response by human deneddylase‐1/SENP8

Abstract

Recent work has revealed a central role for neddylation (conjugation of a Nedd8 moiety) to Cullin‐proteins in the induction of NFκB (via Cullin‐1) and HIF (via Cullin‐2). Here, we elucidate the role of the human deneddylase‐1 (also called SENP8) in inflammatory responses in vitro and in vivo. Human microvascular endothelial cells (HMEC‐1) and HMEC‐1 lacking SENP8 (via lentiviral knockdown) were exposed to LPS or TNF and harvested for analysis of Cullin neddylation, NFκB activation and HIF‐1α stabilization. HMEC‐1 exposure to LPS significantly induced the neddylation of Cullin‐1 and increased NFκB transactivation. These responses were lost in cells lacking SENP8. Further analysis revealed that HIF‐1α protein was stabilized by LPS exposure in wild‐type cells but not in SENP8 knockdown cells. HIF promoter activity was increased following LPS compared to untreated controls. Pharmacological targeting of neddylation (MLN4924) abrogated NF‐κB responses, induced HIF‐1α promoter activity and reduced secretion of TNF‐α‐elicited pro‐inflammatory cytokines. The neddylation inhibitor MLN4924 stabilized HIF and abrogated pro‐inflammatory responses to LPS exposure in vivo. In conclusion, SENP8 is a proximal regulator of Cullin neddylation and fine‐tunes the inflammatory response. Pharmacological inhibition of Cullin neddylation may provide a viable therapeutic opportunity.Funding: German Research Fund (EH 371/1–1), NIH grants DK50189, DK96491 and HL60569.