Metalloproteinase processing of HBEGF is a proximal event in the response of human aortic endothelial cells to oxidized phospholipids

Sangderk Lee, James R. Springstead, Brian W. Parks, Casey E. Romanoski, Roland Palvolgyi, Tiffany Ho, Phuc Nguyen, Aldons J. Lusis, Judith A. Berliner

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Objective-: Atherosclerosis is a chronic inflammatory disease initiated by monocyte recruitment and retention in the vessel wall. An important mediator of monocyte endothelial interaction is the chemokine interleukin (IL)-8. The oxidation products of phospholipids, including oxidized 1-palmitoyl-2- arachidonyl-sn-glycerol-3-phosphocholine (Ox-PAPC), accumulate in atherosclerotic lesions and strongly induce IL-8 in human aortic endothelial cells (HAECs). The goal of this study was to identify the proximal events leading to induction of IL-8 by Ox-PAPC in vascular endothelial cells. Methods And Results-: In a systems genetics analysis of HAECs isolated from 96 different human donors, we showed that heparin-binding EGF-like growth factor (HBEGF) transcript levels are strongly correlated to IL-8 induction by Ox-PAPC. The silencing and overexpression of HBEGF in HAECs confirmed the role of HBEGF in regulating IL-8 expression. HBEGF has been shown to be stored in an inactive form and activation is dependent on processing by a dysintegrin and metalloproteinases (ADAM) to a form that can activate the epidermal growth factor (EGF) receptor. Ox-PAPC was shown to rapidly induce HBEGF processing and EGF receptor activation in HAECs. Using siRNA we identified 3 ADAMs that regulate IL-8 induction and directly demonstrated that Ox-PAPC increases ADAM activity in the cells using a substrate cleavage assay. We provide evidence for one mechanism of Ox-PAPC activation of ADAM involving covalent binding of Ox-PAPC to cysteine on ADAM. Free thiol cysteine analogs showed inhibition of IL-8 induction by Ox-PAPC, and both a cysteine analog and a cell surface thiol blocker strongly inhibited ADAM activity induction by Ox-PAPC. Using microarray analyses, we determined that this ADAM pathway may regulate at least 30% of genes induced by Ox-PAPC in HAECs. Conclusion-: This study is the first report demonstrating a role for the ADAM-HBEGF-EGF receptor axis in Ox-PAPC induction of IL-8 in HAECs. These studies highlight a role for specific ADAMs as initiators of Ox-PAPC action and provide evidence for a role of covalent interaction of Ox-PAPC in activation of ADAMs.

Original languageEnglish (US)
Pages (from-to)1246-1254
Number of pages9
JournalArteriosclerosis, Thrombosis, and Vascular Biology
Volume32
Issue number5
DOIs
StatePublished - May 2012
Externally publishedYes

Keywords

  • Atherosclerosis
  • Endothelium
  • Metalloproteinases
  • Oxidized lipids
  • Signal transduction

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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