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Activating Transcription Factor 1 Directs Mhem Atheroprotective Macrophages Through Coordinated Iron Handling and Foam Cell Protection.
MedLine Citation:
PMID:  22052915     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Rationale:Intraplaque hemorrhage (IPH) drives atherosclerosis through the dual metabolic stresses of cholesterol-enriched erythrocyte membranes and pro-oxidant heme/iron. When clearing tissue hemorrhage, macrophages are typically seen storing either iron or lipid. We have recently defined hemorrhage-associated macrophages (HA-mac) as a plaque macrophage population that responds adaptively to IPH.Objective:This study aimed to define the key transcription factor(s) involved in HO-1 induction by heme.Methods and Results:To address this question, we used microarray analysis and transfection with siRNA and plasmids. To maintain physiological relevance, we focused on human blood-derived monocytes. We found that heme stimulates monocytes through induction of activating transcription factor 1 (ATF-1). ATF-1 coinduces heme oxygenase-1 (HO-1) and Liver X receptor beta (LXR-β). Heme-induced HO-1 and LXR-β were suppressed by knockdown of ATF-1, and HO-1 and LXR-β were induced by ATF-1 transfection. ATF-1 required phosphorylation for full functional activity. Expression of LXR-β in turn led to induction of other genes central to cholesterol efflux, such as LXR-α and ABCA1. This heme-directed state was distinct from known macrophage states (M1, M2, Mox) and, following the same format, we have designated them Mhem.Conclusions:These results show that ATF-1 mediates HO-1 induction by heme and drives macrophage adaptation to intraplaque hemorrhage. Our definition of an ATF-1-mediated pathway for linked protection from foam cell formation and oxidant stress may have therapeutic potential.
Authors:
Joseph J Boyle; Michael Johns; Theresa Kampfer; Aivi T Nguyen; Laurence Game; Dominik J Schaer; Justin C Mason; Dorian O Haskard
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-11-3
Journal Detail:
Title:  Circulation research     Volume:  -     ISSN:  1524-4571     ISO Abbreviation:  -     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0047103     Medline TA:  Circ Res     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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