Peptidyl arginine deiminase-4 exacerbates ischemic AKI by finding NEMO.

ABSTRACT: Peptidyl arginine deiminase-4 (PAD4) catalyzes the conversion of peptidylarginine residues to peptidylcitrulline. We have previously shown that kidney ischemia-reperfusion (I/R) injury increases renal proximal tubular PAD4 expression and activity. Furthermore, kidney PAD4 plays a critical role in ischemic acute kidney injury (AKI) by promoting renal tubular inflammation, neutrophil infiltration, and NF-?B activation. However, the mechanisms of PAD4-mediated renal tubular inflammation and NF-?B activation after I/R remain unclear. Here, we show that recombinant PAD4 preferentially citrullinates recombinant IKK? [also called NF-?B essential modulator (NEMO)] over recombinant IKK? or IKK?. Consistent with this finding, PAD4 citrullinated renal proximal tubular cell IKK? and promoted NF-?B activation via I?B? phosphorylation in vitro. NEMO inhibition with a selective NEMO-binding peptide attenuated PAD4-mediated proinflammatory cytokine mRNA induction in HK-2 cells. Moreover, NEMO inhibition did not affect proximal tubular cell survival, proliferation, or apoptosis, unlike global NF-?B inhibition. In vivo, NEMO-binding peptide treatment protected against ischemic AKI. Finally, NEMO-binding peptide attenuated recombinant PAD4-mediated exacerbation of ischemic AKI, renal tubular inflammation, and apoptosis. Taken together, our results show that PAD4 exacerbates ischemic AKI and inflammation by promoting renal tubular NF-?B activity and inflammation via NEMO citrullination. Targeting NEMO activation may serve as a potential therapy for this devastating clinical problem.

SUBMITTER: Rabadi MM 

PROVIDER: S-EPMC6620589 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature