The overall aim of this grant is to elucidate the novel linkage between copper transport protein "Antioxidant1 (Atox1)" and "NADPH oxidase" involved in inflammatory angiogenesis. Ischemic disease is a leading cause of morbidity and mortality in worldwide. Neovascularization is an important repair process in response to ischemia, which depends on angiogenesis, inflammation and reactive oxygen species (ROS). Copper (Cu), an essential micronutrient, is involved in physiological repair processes such as wound healing and angiogenesis as well as in various pathophysiologies including tumor growth, atherosclerosis and inflammatory diseases. Since excess Cu is toxic, bioavailability of intracellular Cu is tightly controlled by Cu transport proteins such as Cu chaperone Atox1. Our laboratories provided the first evidence that Atox1 functions as a Cu-dependent transcription factor to regulate Cu-induced cell growth. Furthermore, we are one of the first to demonstrate that ROS derived from NADPH oxidase (Nox) play an important role in angiogenic signaling in endothelial cells (ECs) as well as postnatal angiogenesis in response to ischemic injury. However, the role of Cu transport proteins in inflammatory angiogenesis and its linkage with Nox are entirely unknown. Our preliminary data suggest that Atox1 deficient mice have impaired angiogenesis and inflammatory cell recruitment due to decrease in endothelial ROS production in ischemic tissues. Bone marrow (BM) reconstitution indicates that Atox1 in ECs, but not BM cells, is required for post-ischemic revascularization. Based on new preliminary data, we hypothesize that Atox1 functions as a novel regulator for Nox by transcriptional regulation of p47phox as well as activating Rac1;both are critical cytosolic components of Nox, in a Cu-dependent manner. This in turn promotes ROS-dependent signaling linked to inflammatory and angiogenic responses in ECs, which contributes to neovascularization in response to ischemic injury.
Aim1 will focus on establishing a role of Atox1 in regulating NADPH oxidase and ROS-dependent inflammatory and angiogenic signaling and function in ECs in a Cu-dependent manner.
Aim 2 will focus on identifying molecular mechanisms of how Atox1 is involved in activation of NADPH oxidase through transcriptional regulation of p47phox and activating Rac1 via binding to a Rac1-binding scaffold protein IQGAP1 in ECs in a Cu-dependent manner.
Aim 3 will focus on determining the functional role of Atox1 in neovascularization in vivo by regulating ROS production, angiogenesis and inflammatory cell recruitment in injured tissues in a Cu-dependent manner using hindlimb ischemia model with Atox1-/- mice. Bone marrow transplantation, in vivo intravital microscopy and bioluminescence imaging, highly innovative Cu imaging analysis in vitro and in vivo will be performed. Our study will provide novel insight into Cu transport protein and their regulators as potential therapeutic targets for treatment of angiogenesis- and inflammation-dependent ischemic cardiovascular diseases.
Ischemic disease, the most common cause of morbidity and death in western countries, is increasing worldwide and is due in part to impaired formation of new blood vessels, which depends on angiogenesis, inflammation, and reactive oxygen species. Copper is an essential nutrient and is shown to be involved in regulating inflammation and angiogenesis with unknown mechanism. This proposal will provide novel insights into Cu transport proteins and its regulators as potential therapeutic targets for inflammation- and angiogenesis-dependent ischemic cardiovascular diseases.
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