Abstract P275: Transglutaminase-2 Contributes to Angiotensin II-Induced Reactive Oxygen Species Production in Mice

Abstract

Transglutaminase type II (TG2) is a pleiotropic enzyme that exhibits various activities and it is involved in diverse biological functions, including cell signaling, cytoskeleton rearrangements, displaying enzymatic activities. We previously demonstrated that TG2 may contribute to angiotensin II-induced reduction of NO bioavailability as well as to the impaired vascular functional and structural alterations induced by angiotensin II. Here we hypothesized that TG2 may contribute to increased production of reactive oxygen species (ROS) in the vasculature of angiotensin-II-treated mice. TG2-knockout mice (TG2-K/O, 8 weeks old, n=6) and age-matched wild type (WT) control mice were treated or not with angiotensin-II (400ng/kg/min) for 14 days. TG2 activity in aorta was measured by ELISA. ROS production in aorta was evaluated by dihydroethidium staining. The expression of angiotensin type1 receptor (AT1R), TG2, NOX-1, and ERp72 (the positive modulator of NOX-1) was evaluated in aorta by immunoblotting, coimmunoprecipitation analysis was also performed. As expected, TG2-K/O lacked TG2 expression and activity. Angiotensin-II significantly increased (2-fold) TG2 expression and activity only in WT. AT1R expression in aorta was not influenced by Angiotensin II treatment in both WT and TG2K/O mice. ROS production was similar in WT and TG2-K/O and increased only in angiotensin-II-treated WT (+9%, p<0.01). NOX-1 and ERp72 expression was similar in WT and TG2-K/O. Angiotensin-II significantly increased NOX-1 (+23%, p<0.01) and ERp72 (+29%, p<0.01) only in WT. Only in aorta from WT and not from TG2-K/O, TG2 was successfully immunoprecipitated by AT1 and ERP72, indicating that TG2 is able to interact with both proteins, and suggesting that it may be involved in angiotensin II- induced NOX modulation and ROS production. In conclusion, Angiotensin-II increased ROS production and NOX-1 expression and activation only in presence of TG2 in WT. TG2 interacts with both AT1R and ERp72. Thus, TG2 may contribute to NOX-induced ROS production in mice treated with angiotensin-II.