NITRO-FATTY ACID IRREVERSIBLE INHIBITION OF PTP1B

REYES AB; VAZQUEZ MM; SUBIRADA CALDARONE PAULA; SANCHEZ MC; BONACCI GR

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular November 3; 2015

Insulin signaling impairment is associated with type II diabetes and obesity. This molecular pathway is tightlyregulated by protein kinases and protein phosphatases activity. Lack of PTP1B activity improves insulin sensitivityand blood glucose levels. PTP1B enclose a cysteine in the catalytic domain which turns out an important modulatorof its activity by reactive oxygen species (ROS). Recently, we have shown that systemic nitro-oleic acid (NO2-OA)administration reduces insulin resistance in a diabetic (ob/ob) mouse model and increases glucose uptake. Nitro-fattyacid derived activates, in part, PPARγ dependent gene expression. However, the thiol reactivity of NO2-OA appearsto play a crucial role in modulate insulin sensitivity by inhibited PTP1B activity. Our results demonstrated thatenzyme activity was dose dependent and irreversible inhibited by NO2-OA as shown by GSH and BME competition.Furthermore, mass spectrometry analysis revealed NO2-OA covalent adducted to different nucleophile residue onPTP1B, including the cysteine 215. In addition, extended insulin phosphorilation of AKT, and MAPK in 3T3-L1 cellpretreated with NO2-OA compared with untreated cells. Thus, we have characterized the inhibition of PTP1B bynitro-alkylation of cys-215, a mechanism that suggests the participation of NO2-FA in the insulin signaling pathwayvia PPARγ independent manner.