Glutaredoxin (Grx1) is a ubiquitously expressed thiol-disulfide oxidoreductase that specifically catalyzes reduction of S-glutathionylated substrates. Grx1 is known to be a key regulator of pro-inflammatory signaling, and Grx1 silencing inhibits inflammation in inflammatory disease models. Therefore, we anticipate that inhibition of Grx1 could be an anti-inflammatory therapeutic strategy. We used a rapid screening approach to test 504 novel electrophilic compounds for inhibition of Grx1, which has a highly reactive active-site cysteine residue (pKa 3.5). From this chemical library a chloroacetamido compound, CWR-J02, was identified as a potential lead compound to be characterized. CWR-J02 inhibited isolated Grx... More
Glutaredoxin (Grx1) is a ubiquitously expressed thiol-disulfide oxidoreductase that specifically catalyzes reduction of S-glutathionylated substrates. Grx1 is known to be a key regulator of pro-inflammatory signaling, and Grx1 silencing inhibits inflammation in inflammatory disease models. Therefore, we anticipate that inhibition of Grx1 could be an anti-inflammatory therapeutic strategy. We used a rapid screening approach to test 504 novel electrophilic compounds for inhibition of Grx1, which has a highly reactive active-site cysteine residue (pKa 3.5). From this chemical library a chloroacetamido compound, CWR-J02, was identified as a potential lead compound to be characterized. CWR-J02 inhibited isolated Grx1 with an IC50 value of 32 μM in the presence of 1 mM glutathione. Mass spectrometric analysis documented preferential adduction of CWR-J02 to the active site Cys-22 of Grx1, and molecular dynamics simulation identified a potential non-covalent binding site. Treatment of the BV2 microglial cell line with CWR-J02 led to inhibition of intracellular Grx1 activity with an IC50 value (37 μM). CWR-J02 treatment decreased lipopolysaccharide-induced inflammatory gene transcription in the microglial cells in a parallel concentration-dependent manner, documenting the anti-inflammatory potential of CWR-J02. Exploiting the alkyne moiety of CWR-J02, we used click chemistry to link biotin azide to CWR-J02-adducted proteins, isolating them with streptavidin beads. Tandem mass spectrometric analysis identified many CWR-J02-reactive proteins, including Grx1 and several mediators of inflammatory activation. Taken together, these data identify CWR-J02 as an intracellularly effective Grx1 inhibitor that may elicit its anti-inflammatory action in a synergistic manner by also disabling other pro-inflammatory mediators. The CWR-J02 molecule provides a starting point for developing more selective Grx1 inhibitors and anti-inflammatory agents for therapeutic development.
