Research On The Mechanism Of Thioredoxin Regulating Allograft Inflammation Factor1(AIF-1)

Inflammation is the defense reaction of the body aims at cumulativedamage factor, and is a complex process involved with a variety of cellsand cytokines. Inflammation causes a series of cytokines and acts onthe multiple systems and organs of the body, causing damage. Thereforethe mutual regulaton of cytokines plays an important role in balancing theinflammatory processes, and coltroling the development of inflammation.AIF-1(Allograft inflammatory factor-1), A kind of calcium bindingprotein induced by interferon gamma (IFN-γ), was originally cloned fromactivated macrophages in atherosclerotic allogeneic heart graftsundergoing chronic immune rejection in humans. The expression ofAIF-1was significantly enhanced in liver, kidney and heart allograftrejections. AIF-1is also involved in inflammatory responses andreproductive immunity as well as in immune activation and macrophagefunctions. AIF-1may play roles in autoimmune diseases such asatherosclerotic vasculopathy.Trx are small ubiquitous12kDa multifuncational proteins containingthe conserved active catalytic domain(WCGPC). Thioredoxin system,which consists of Trx, thioredoxin reductase(TrxR) and nicotinamideadenine dinucleotide phosphate(NADPH), and it plays an important roleinside the cells against oxidative stress and maintain normal redoxbalance．Studies have shown that Trx can stimulate the expression of avariety of cytokines together. As a kind of multi-functional inflammationfactors, AIF-1has become a hot topic in the inflammation due to its closerelevance to the body’s immune reponse and cardiovascular disease. Inthis study, we investigated whether and how the location of Trx isinvolved in the regulation of AIF-1.The study conducted in this work andthe results obtained therein are follows:Two recombinant plasmids pcDNA-Trx, pcDNA-NLS-Trx and the plamids pcDNA3.1were transiently transfected into U937cells,respectively. Trx in both the cytoplasm and nucleus can up-regulate theprotein levels of AIF-1, however, only Trx in the nucleus up-regulates themRNA levels of AIF-1.The nuclear Trx can not enhance the expression of AIF-1when theactivity of NF-κB is blocked by BAY11-7082, and the cytoplasm Trx cannot enhance the expression of AIF-1when the activity of ER is blockedby Tamoxifen, an inhibitor of ERβ. These results demonstrated Trx withdifferent subcellular localization had different mechanism to regulateAIF-1: Trx was able to upregulate the levels of AIF-1in U937cells viathe NF-κB pathway in the nucleus and the ERβ pathway in the cytoplasm.Moreover, nuclear Trx played more important roles in regulating theAIF-1levels than cytoplasmic Trx.These findings raise the possibility that Trx may be a moleculartarget for the treatment of inflammatory diseases mediated by AIF-1.