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Thioredoxin‐Interacting Protein Mediates Hcys‐induced NLRP3 Inflammasome Activation in Mouse Podocytes
Author(s) -
Abais Justine,
Boini Krishna M.,
Xia Min,
Li PinLan
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.704.7
Subject(s) - txnip , inflammasome , aim2 , thioredoxin , microbiology and biotechnology , thioredoxin interacting protein , chemistry , signal transducing adaptor protein , nadph oxidase , reactive oxygen species , signal transduction , oxidative stress , biochemistry , biology , receptor
Our recent studies have demonstrated that reactive oxygen species (ROS) derived from NADPH oxidase activates NLRP3 inflammasomes causing homocysteine (Hcys)‐induced podocyte and glomerular injury. However, the precise mechanism regarding how ROS activates the inflammasome is still unknown. The current study explored whether thioredoxin‐interacting protein (TXNIP) mediates Hcys‐induced NLRP3 inflammasome activation in cultured podocytes. TXNIP, the regulatory inhibitor of the antioxidant thioredoxin (TRX), is thought to dissociate from TRX in response to elevated levels of oxidative stress to bind to inflammasome protein NLRP3 and activate the inflammasome complex. It was found that TXNIP protein expression was decreased by Hcys treatment in a concentration‐dependent manner. However, TRX protein expression increased upon Hcys stimulation. At an inflammasome‐activating dose of 40 μM Hcys, TXNIP protein expression decreased by 60.4% and TRX increased 2.0‐folds versus the control. However, co‐immunoprecipitation demonstrated that Hcys increased TXNIP binding to NLRP3 by 1.5‐folds over the control, which was attenuated by TXNIP siRNA. Confocal microscopy showed that inhibition of TXNIP also prevented Hcys‐induced NLRP3 inflammasome formation by reducing colocalization of NLRP3 with ASC or caspase‐1. Hcys‐induced NLRP3 inflammasome activation was also attenuated by TXNIP siRNA, as shown by a 45.3% inhibition of caspase‐1 activity and 39.2% reduction of IL‐1β production. In addition, TXNIP inhibition protected podocytes from injury as demonstrated by normal expression levels of podocyte markers like podocin and desmin. From these results it is concluded that TXNIP binding to inflammasome protein NLRP3 is a key signaling mechanism for Hcys‐induced formation and activation of the NLRP3 inflammasome, thereby inducing podocyte injury (supported by NIH grants DK54927 and 1F31AG043289).