title: Glutaredoxin 2a overexpression in macrophages promotes mitochondrial dysfunction but has little or no effect on atherogenesis in LDL-receptor null mice.
abstract: OBJECTIVE
  Reactive oxygen species (ROS)-mediated formation of mixed disulfides between critical cysteine residues in proteins and glutathione, a process referred to as protein S-glutathionylation, can lead to loss of enzymatic activity and protein degradation. Since mitochondria are a major source of ROS and a number of their proteins are susceptible to protein-S-glutathionylation, we examined if overexpression of mitochondrial thioltranferase glutaredoxin 2a (Grx2a) in macrophages of dyslipidemic atherosclerosis-prone mice would prevent mitochondrial dysfunction and protect against atherosclerotic lesion formation.
  
  
  RESULTS
  We generated transgenic Grx2aMac(LDLR-/-) mice, which overexpress Grx2a as an EGFP fusion protein under the control of the macrophage-specific CD68 promoter. Transgenic mice and wild type siblings were fed a high fat diet for 14 weeks at which time we assessed mitochondrial bioenergetic function in peritoneal macrophages and atherosclerotic lesion formation. Flow cytometry and Western blot analysis demonstrated transgene expression in blood monocytes and peritoneal macrophages isolated from Grx2aMac(LDLR-/-) mice, and fluorescence confocal microscopy studies confirmed that Grx2a expression was restricted to the mitochondria of monocytic cells. Live-cell bioenergetic measurements revealed impaired mitochondrial ATP turnover in macrophages isolated from Grx2aMac(LDLR-/-) mice compared to macrophages isolated from non-transgenic mice. However, despite impaired mitochondrial function in macrophages of Grx2aMac(LDLR-/-) mice, we observed no significant difference in the severity of atherosclerosis between wildtype and Grx2aMac(LDLR-/-) mice.
  
  
  CONCLUSIONS
  Our findings suggest that increasing Grx2a activity in macrophage mitochondria disrupts mitochondrial respiration and ATP production, but without affecting the proatherogenic potential of macrophages. Our data suggest that macrophages are resistant against moderate mitochondrial dysfunction and rely on alternative pathways for ATP synthesis to support the energetic requirements.
authors.affiliation: Department of Biology, Trinity University, San Antonio, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Zamora
authors.affiliation: Department of Clinical Laboratory Sciences, University of Texas Health Science Center at San Antonio, USA.
authors.forename: K P
authors.initials: KP
authors.lastname: Downs
authors.affiliation: Department of Kinesiology, Health, and Nutrition, University of Texas at San Antonio, San Antonio, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Ullevig
authors.affiliation: Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, USA.
authors.forename: S
authors.initials: S
authors.lastname: Tavakoli
authors.affiliation: Department of Clinical Laboratory Sciences, University of Texas Health Science Center at San Antonio, USA.
authors.forename: H S
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Clinical Laboratory Sciences, University of Texas Health Science Center at San Antonio, USA.
authors.forename: M
authors.initials: M
authors.lastname: Qiao
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
authors.forename: D R
authors.initials: DR
authors.lastname: Greaves
authors.affiliation: Department of Clinical Laboratory Sciences, University of Texas Health Science Center at San Antonio, USA; Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, USA; Department of Biochemistry, University of Texas Health Science Center at San Antonio, USA. Electronic address: asmis@uthscsa.edu.
authors.forename: R
authors.initials: R
authors.lastname: Asmis
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000201:enzymology / Q000473:pathology; D001018:Aortic Diseases / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D017209:Apoptosis; D050197:Atherosclerosis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004734:Energy Metabolism; D054477:Glutaredoxins / Q000235:genetics / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000201:enzymology* / Q000473:pathology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008928:Mitochondria / Q000201:enzymology* / Q000473:pathology; D058226:Plaque, Atherosclerotic; D011973:Receptors, LDL / Q000172:deficiency* / Q000235:genetics; D012720:Severity of Illness Index
chemical_list: C516009:Glrx2 protein, mouse; D054477:Glutaredoxins; D011973:Receptors, LDL; D000255:Adenosine Triphosphate
keywords: Atherosclerosis; Glutaredoxin 2; Macrophage; Mitochondria; Reactive oxygen species; Thiols