Abstract 13113: Identification of Novel Copper-dependent Wound Repair Mechanism: Role of Copper Transport Protein Antioxidant 1

Abstract

Copper (Cu) facilitates wound healing and angiogenesis with unknown mechanism. Bioavailability of Cu is controlled by transport-proteins, including cytosolic Cu-chaperone Atox1, which is required for activation of secretory Cu enzymes. Atox1 also functions as a Cu-dependent transcription factor, but its role in wound healing is unknown. Using mouse skin puncture model, here we show that Atox1 protein (8-fold) and Cu-level (by X-ray Fluorescence Microscopy; 2.5-fold) were increased in wounding tissue in wild type (WT) mice at day 7 when Atox1 was localized in nucleus of dermal endothelial cells (ECs) as well as cytosol of epidermal cells, granulation tissue. Furthermore, topical Cu treatment enhanced (20% vs PBS), but specific Cu chelator BCS reduced wound repair in WT mice. Importantly, Atox1 knockout (KO) mice showed abolished topical Cu-induced wound repair or impaired endogenous wound healing vs. WT mice, which was associated with decreased angiogenesis (CD31+, 45% ), proliferation (BrdU+, 60%), ROS-production (DHE+), collagen formation (Masson's Trichrome), and infiltration of macrophage (Mac3+,40%) which secrets angiogenic cytokines VEGF and SDF-1α. Mechanistically, Atox1KO mice exhibited reduced wounding-induced expression of Atox1 target proteins such as p47phox NADPH oxidase and cyclin D1 as well as extracellular matrix secretory Cu-enzyme lysyl oxidase activity. Finally, bone marrow (BM) transplantation revealed that Atox1 in both BM and tissue resident cells are required for wound repair. Consistently, Atox1 protein and Cu were markedly increased in WT-BM tissue after wounding. Impaired wound healing in Atox1 KO mice was rescued by both Atox1-gene transfer and WT-BM topical treatment in wound tissues. In summary, Atox1 senses Cu to accelerate wound healing/repair by promoting angiogenesis, inflammatory cell recruitment, proliferation, extracellular matrix maturation as well as BM cell function. Taken together, Cu-Atox1-based therapy may represent a novel therapeutic strategy to promote dermal wound healing and tissue regeneration.