Electronegative LDL induction of apoptosis in macrophages: involvement of Nrf2.
The aim of this study was to determine the apoptotic pathways and mechanisms involved in electronegative LDL [LDL(-)]-induced apoptosis in RAW 264.7 macrophages and the role of Nrf2 in this process. Incubation of RAW 264.7 macrophages with LDL(-) for 24 h resulted in dose-dependent cell death. Activated caspases were shown to be involved in the apoptosis induced by LDL(-); incubation with the broad caspase inhibitor z-VAD prevented apoptosis in LDL(-)-treated cells. CD95 (Fas), CD95 ligand (FasL), CD36 and the tumor necrosis factor (TNF) ligand Tnfsf10 were overexpressed in LDL(-)-treated cells. However, Bax, Bcl-2 and Mcl-1 protein levels remained unchanged after LDL(-) treatment. LDL(-) promoted hyperpolarization of the mitochondrial membrane, elevated reactive oxygen species (ROS) production and translocation of Nrf2 to the nucleus, a process absent in cells treated with native LDL. Elicited peritoneal macrophages from Nrf2-deficient mice exhibited an elevated apoptotic response after challenge with LDL(-), together with an increase in the production of ROS in the absence of alterations in CD36 expression. These results provide evidence that CD36 expression induced by LDL(-) is Nrf2-dependent. Also, it was demonstrated that Nrf2 acts as a compensatory mechanism of LDL(-)-induced apoptosis in macrophages.
Pedrosa
A M C
AM
Department of Clinical and Toxicology Analysis, Faculty of Pharmaceutical Sciences, University of São Paulo, 05508-900, Sao Paulo, Brazil.
Faine
L A
LA
Grosso
D M
DM
de Las Heras
B
B
Boscá
L
L
Abdalla
D S P
DS
D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism; D053222:Fas Ligand Protein / Q000235:genetics / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015415:Biomarkers; D018955:CD36 Antigens; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008077:Lipoproteins, LDL; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D012333:RNA, Messenger; D017382:Reactive Oxygen Species