Targeting the Deubiquitinase STAMBP Inhibits NALP7 Inflammasome
ARTICLE Received 19 Jul 2016 | Accepted 8 Mar 2017 | Published 11 May 2017 DOI: 10.1038/ncomms15203 OPEN Targeting the deubiquitinase STAMBP inhibits NALP7 inflammasome activity Joseph S. Bednash1, Nathaniel Weathington1, James Londino1, Mauricio Rojas1, Dexter L. Gulick1, Robert Fort1, SeungHye Han1, Alison C. McKelvey1, Bill B. Chen1 & Rama K. Mallampalli1,2,3 Inflammasomes regulate innate immune responses by facilitating maturation of inflammatory cytokines, interleukin (IL)-1b and IL-18. NACHT, LRR and PYD domains-containing protein 7 (NALP7) is one inflammasome constituent, but little is known about its cellular handling. Here we show a mechanism for NALP7 protein stabilization and activation of the inflammasome by Toll-like receptor (TLR) agonism with bacterial lipopolysaccharide (LPS) and the synthetic acylated lipopeptide Pam3CSK4. NALP7 is constitutively ubiquitinated and recruited to the endolysosome for degradation. With TLR ligation, the deubiquitinase enzyme, STAM-binding protein (STAMBP) impedes NALP7 trafficking to lysosomes to increase NALP7 abundance. STAMBP deubiquitinates NALP7 and STAMBP knockdown abrogates LPS or Pam3CSK4-induced increases in NALP7 protein. A small-molecule inhibitor of STAMBP deubiquitinase activity, BC-1471, decreases NALP7 protein levels and suppresses IL-1b release after TLR agonism. These findings describe a unique pathway of inflammasome regulation with the identification of STAMBP as a potential therapeutic target to reduce pro-inflammatory stress. 1 Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, UPMC Montefiore, NW 628, Pittsburgh, Pennsylvania 15213, USA. 2 Departments of Cell Biology and Physiology and Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. 3 Medical Specialty Service Line, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania 15240, USA.
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