Abstract 15729: Copper Transporter ATP7A Limits Vascular Inflammation and Aortic Aneurysm Development

Abstract

Vascular inflammation and its-induced endothelial cell (EC) barrier dysfunction contribute to aortic aneurysm (AA) development. However, critical regulators of AA are poorly understood. Copper (Cu), an essential micronutrient, at excess level is shown to promote inflammatory diseases including AA with unknown mechanism. Cu transporting ATPase (ATP7A) functions to deliver Cu to the secretory extracellular matrix enzyme lysyl oxidase (LOX) via Cu chaperone Atox1, or exclude Cu. Here we show that ATP7A is a key regulator of vascular inflammation and AA formation using ATP7A mutant (ATP7Amut) mice with reduced Cu transport function. ATP7Amut/ApoE-/- mice fed with high fat diet (HFD) induced a robust AA formation (70%) with enhanced atherosclerotic lesion (3.9 fold), which was associated with increased macrophage recruitment and matrix metalloproteinase 2 & 9 activity vs. ApoE-/-/HFD or Atox1-/-/ApoE-/-/HFD mice. Of note, both ATP7Amut and Atox1-/- mice showed similar extent of reduced LOX activity (54%) indicating that decrease in LOX activity was not sufficient to develop AA. However, EC permeability was markedly increased only in ATP7Amut/ApoE-/- mice. Mechanistically, ATP7A depletion or proinflammatory cytokine TNFα in HUVECs increased EC permeability (132%) and leukocyte transendothelial migration (TEM) (p<0.05) in a Cu dependent manner. To determine the ATP7A dependent microRNAs (miRs), we performed miRs array and found that miR125b is highly upregulated (9 fold) miRs in ATP7A depleted ECs. Of note, miR125b is shown to suppress VE-Cadherin (VE-Cad) expression by inhibiting translation of 3’UTR of VE-cad mRNA. Consistent with this, ATP7A depletion upregulated miR125b and downregulated VE-Cad, thereby increasing EC permeability, which were rescued by anti-miR125b. Furthermore, ATP7A knockdown caused Rac1-mediated actin disassembly in Cu dependent manner, which also contributed to EC barrier dysfunction. In summary, endothelial ATP7A protects against AA formation by preventing inflammation-induced EC permeability and excess inflammatory recruitment via regulating actin reorganization, VE-Cad expression, and LOX activity in a Cu dependent manner. Thus, ATP7A is a potential therapeutic target for inflammatory vascular disease.