Abstract 13097: Novel Interaction of Antioxidant-1 With NADPH Oxidase p47phox and TRAF4: Role in TNFα-Induced Inflammation and Atherosclerosis
Tumor necrosis factor-TNFα plays a key role in atherosclerosis via NADPH oxidase-derived reactive oxygen species (ROS) and its downstream redox-sensitive inflammatory responses. Copper (Cu) has been implicated in atherosclerosis and inflammation with unknown mechanism. Bioavailability of Cu is controlled by transport-proteins including Cu-chaperone Atox1 which obtains Cu via Cu-importer CTR1 localized at plasma membrane. We recently found that Atox1 also functions as a Cu-dependent transcription factor for NADPH oxidase p47phox. However, role of Atox1 in atherosclerosis is unknown. Here we show that ApoE-/-Atox1-/- mice with 16 weeks high-fat-diet (HFD) showed decreased atherosclerotic lesion (40%, Oil-O-red staining). inflammatory cell recruitment (50% decrease, Mac3+) and extracellular matrix deposition (Masson’s Trichrome) compared to ApoE-/-HFD. Mechanistically, in cultured endothelial cells (ECs), Atox1 knockdown with siRNA, or Cu-chelator BCS inhibited TNFα-induced ROS production (70%) at later phase (16hrs) and its downstream VCAM1/ICAM1 expression and monocyte adhesion by reducing transcription of p47phox. Unexpectedly, TNFα stimulation rapidly promoted Atox1/p47phox binding in a PKCδ-dependent and Cu-“independent” manner, which is required for p47phox membrane translocation involved in early phase of (5min) ROS production and subsequent Cys oxidation of Cu-importer CTR1 detected by a biotin-labeled Cys-OH trapping reagent. This was followed by CTR1/Cu-dependent Atox1 binding to TNFα receptor associated factor (TRAF)4, which promoted Atox1 nuclear translocation to increase p47phox expression leading to late-phase of ROS production, facilitating further monocyte adhesion to ECs. In summary, Atox1 plays an important role in activating p47phox-based NADPH oxidase and inflammatory responses in ECs by binding to p47phox that induces early phase of ROS to promote CTR1 oxidation in Cu-independent manner. This is followed by Cu-dependent Atox1/TRAF4 binding required for Atox1 nuclear translocation to function as a transcription factor for p47phox, leading to late-phase of ROS production, which contributes to acceleration of atherosclerosis in vivo.
Author Disclosures: A. Das: None. S. Varadarajan: None. G. Chen: None. B. Surenkhuu: None. J. Tian: None. M. Ushio-Fukai: None. T. Fukai: None.
- © 2015 by American Heart Association, Inc.