Inhibition of neddylation plays protective role in lipopolysaccharide-induced kidney damage through CRL-mediated NF-κB pathways

It has been shown that NF-κB signaling path is very effective pharmacological target for the treatment of various inflammatory diseases, including bacterial infection-associated acute kidney injury (AKI), which remains a main cause of disability and death in patients. Notably, IκB, the upstream molecular of NF-κB, plays an important role by inhibiting NF-κB activity, and IκB is regulated by cullin-RING E3 ligases (CRLs)-mediated proteasomal degradation. Therefore inhibition of CRLs-mediated neddylation and degradation of IκB would prevent NF-κB-mediated inflammation. MLN4924, a potent neddylation-inhibiting pharmacological agent, has been shown to have significant protective effects against lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production through restriction of the CRL-mediated NF-κB pathway. However, it is still unclear whether MLN4924 plays a protective role through its anti-inflammatory properties in sepsis-induced AKI. In the current research, we explored whether MLN4924 have anti-inflammatory action in LPS-induced AKI mice. Our results show that MLN4924 dramatically decreased the cytotoxicity of LPS and inhibited LPS-induced synthesis and release of pro-inflammatory cytokines, such as TNF-α, IL-6 and IL-1β, in HK2 cells, a renal tubular cell line. In addition, MLN4924 inhibited Nedd8-activating enzymes, which broke the process of cullin proteins neddylation and subsequent CRL target proteins degradation. The MLN4924-induced degradation of CRL attenuated the phosphorylation modification of IκB and IKK-α/β and blocked the nuclear translocation of P50-NF-κB and P65-NF-κB in HK2 cells under LPS stimulation. Finally, our in vivo results show that MLN4924 protected against LPS-induced AKI at relatively low doses. Collectively, these results suggest that pharmacologically blocking neddylation by MLN4924 results in the suppression of pro-inflammatory cytokines generation through the CRL/NF-κB pathway in LPS-stimulated HK2 cells, and attenuated renal inflammation in LPS-induced AKI.