Role of MP-HBEGF-EGFR signaling for inflammatory action of oxidized phospholipids

The main goal of this study is to define proximal events in Ox-PAPC activation of endothelial cells to identify mechanism of lesion development of atherosclerosis. We reported that cell surface metalloproteinase (MP) activation is a key event for inflammatory process of endothelial cells induced by Ox-PAPC. During the next 3 yrs of independent phase, I will focus on the in-depth mechanistic studies for MP activation by oxidized phospholipid (Ox-PAPC) using in vitro cell system and in vivo mouse models of atherosclerosis. In addition, using system approaches using expression and genotyping array data I will also focus on identification of the novel genetic factors and pathways that regulate MP-mediated Ox-PAPC signals. In aim 1, I will identify mechanisms by which Ox-PAPC or its bioactive component PEIPC induces activation of MPs focusing on two candidate mechanisms: direct modification of MP by Ox-PAPC and induction of cholesterol depletion in endothelial cells. In aim 2, I will determine if MP-HBEGF-EGFR pathway is indeed activated in lesion areas using mouse aortic and in human endarterectomized samples using quantitative immunochemistry. In addition, I will directly test the role of HBEGF in LDLR-/- null mice using HBEGF antisense oligonucleotide developed by collaborator ISIS Pharmaceuticals. I will also examine the lesion formation of endothelial-specific cholesterol depletion using endothelial-specific SCAP null mice under LDLR-/-. Recent our observation showed that this genetically modified mouse showed significant increased lesion formation. From transcript and genotyping data in HAECs isolated from 147 donors, we reported genetic factors and SNPs. We also constructed gene co-expression network to find gene modules highly connected for regulation. In aim 3, a systems genetics approach will be used to identify and validate the significance of novel genetic factors (genes and SNPs) and cell pathways that regulates MP-HBEF-EGFR pathway. I will apply information from this gene co-expression network to identify novel pathways in pathway analysis. In summary, the proposed study will determine the mechanism of endothelial MP-HBEGF-EGFR pathway in lesion development, and test the possibility of targeting against atherosclerosis.