title: AKT/protein kinase B regulation of BCL family members during oxysterol-induced apoptosis.
abstract: Cells of the vasculature, including macrophages, smooth muscle cells, and endothelial cells, exhibit apoptosis in culture upon treatment with oxidized low density lipoprotein, as do vascular cells of atherosclerotic plaque. Several lines of evidence support the hypothesis that the apoptotic component of oxidized low density lipoprotein is one or more oxysterols, which have been shown to induce apoptosis through the mitochondrial pathway. Activation of the mitochondrial pathway of apoptosis is regulated by members of the BCL family of proteins. In this study, we demonstrate that, in the murine macrophage-like cell line P388D1, oxysterols (25-hydroxycholesterol and 7-ketocholesterol) induced the degradation of the prosurvival protein kinase AKT (protein kinase B). This led, in turn, to the activation of the BCL-2 homology-3 domain-only proteins BIM and BAD and down-regulation of the anti-apoptotic multi-BCL homology domain protein BCL-xL. These responses would be expected to activate the pro-apoptotic multi-BCL homology domain proteins BAX and BAK, leading to the previously reported release of cytochrome c observed during oxysterol-induced apoptosis. Somewhat surprisingly, small interfering RNA knockdown of BAX resulted in a complete block of the induction of apoptosis by 25-hydroxycholesterol.
authors.affiliation: Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614-0581, USA.
authors.forename: Antonio E
authors.initials: AE
authors.lastname: Rusiñol
authors.forename: Douglas
authors.initials: D
authors.lastname: Thewke
authors.forename: June
authors.initials: J
authors.lastname: Liu
authors.forename: Natalie
authors.initials: N
authors.lastname: Freeman
authors.forename: Sankhavaram R
authors.initials: SR
authors.lastname: Panini
authors.forename: Michael S
authors.initials: MS
authors.lastname: Sinensky
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006888:Hydroxycholesterols / Q000378:metabolism; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D010741:Phospholipases A / Q000737:chemistry; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013261:Sterols / Q000378:metabolism*; D013997:Time Factors; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; C494773:Bak1 protein, mouse; C494827:Bax protein, mouse; D000072224:Bcl-2-Like Protein 11; C494812:Bcl2l1 protein, mouse; C000606776:Bcl2l11 protein, mouse; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D006888:Hydroxycholesterols; D008164:Luminescent Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D013261:Sterols; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D049452:Green Fluorescent Proteins; C007997:25-hydroxycholesterol; D045304:Cytochromes c; D002784:Cholesterol; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D010741:Phospholipases A; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases