Targeting TRAF3IP2 by Genetic and Interventional Approaches Inhibits Ischemia/Reperfusion-induced Myocardial Injury and Adverse Remodeling

John M Erikson,Anthony J Valente,Srinivas Mummidi,Hemanth Kumar Kandikattu,Vincent G Demarco,Shawn B Bender,William P Fay,Ulrich Siebenlist,Bysani Chandrasekar

doi:10.1074/jbc.m116.764522

Abstract

Re-establishing blood supply is the primary goal for reducing myocardial injury in subjects with ischemic heart disease. Paradoxically, reperfusion results in nitroxidative stress and a marked inflammatory response in the heart. TRAF3IP2 (TRAF3 Interacting Protein 2; previously known as CIKS or Act1) is an oxidative stress-responsive cytoplasmic adapter molecule that is an upstream regulator of both IκB kinase (IKK) and c-Jun N-terminal kinase (JNK), and an important mediator of autoimmune and inflammatory responses. Here we investigated the role of TRAF3IP2 in ischemia/reperfusion (I/R)-induced nitroxidative stress, inflammation, myocardial dysfunction, injury, and adverse remodeling. Our data show that I/R up-regulates TRAF3IP2 expression in the heart, and its gene deletion, in a conditional cardiomyocyte-specific manner, significantly attenuates I/R-induced nitroxidative stress, IKK/NF-κB and JNK/AP-1 activation, inflammatory cytokine, chemokine, and adhesion molecule expression, immune cell infiltration, myocardial injury, and contractile dysfunction. Furthermore, Traf3ip2 gene deletion blunts adverse remodeling 12 weeks post-I/R, as evidenced by reduced hypertrophy, fibrosis, and contractile dysfunction. Supporting the genetic approach, an interventional approach using ultrasound-targeted microbubble destruction-mediated delivery of phosphorothioated TRAF3IP2 antisense oligonucleotides into the LV in a clinically relevant time frame significantly inhibits TRAF3IP2 expression and myocardial injury in wild type mice post-I/R. Furthermore, ameliorating myocardial damage by targeting TRAF3IP2 appears to be more effective to inhibiting its downstream signaling intermediates NF-κB and JNK. Therefore, TRAF3IP2 could be a potential therapeutic target in ischemic heart disease.

Highlights

Affairs, Office of Research and Development-Biomedical Laboratory Research and Development (ORD-BLRD) Service Award I01-BX002255
Reperfusion of the ischemic myocardium is the primary goal of reducing myocardial injury and dysfunction, paradoxically it can produce pathological effects by the (i) excessive generation of reactive oxygen and nitrogen species, (ii) activation of the redox-sensitive dimeric transcription factors NF-␬B and AP-1, (iii) up-regulation of inflammatory mediators, (iv) recruitment and activation of immune and inflammatory cells, and (v) induction of cardiomyocyte apoptosis, which results in myocardial injury, dysfunction, and adverse remodeling [2, 3]
TRAF3IP2 physically associates with IKK and activates NF-␬B [15], we have previously demonstrated that its physical interaction with IKK␥ results in Jun N-terminal kinase (JNK) activation in cardiomyocytes [17], suggesting that induction of TRAF3IP2 could result in activation of proinflammatory signal transduction pathways regulated by both IKK/NF-␬B and JNK/AP-1

Summary

Results

I/R Induces TRAF3IP2 Expression in the Heart—Previously, we demonstrated that 30-min ischemia/2-h reperfusion induces oxidative stress and activation of the oxidative stressresponsive transcription factors NF-␬B and AP-1 in the heart [23,24,25,26].

The abbreviations used are

Discussion

Experimental Procedures