title: Expression of Bcl-x, Bcl-2, Bax, and Bak in endarterectomy and atherectomy specimens.
abstract: The regulation of apoptosis in atherosclerosis is not completely defined. The aim of this study was to determine the expression of Bcl-2, Bcl-x, Bax, and Bak in relation to apoptosis in advanced atherosclerotic lesions. In atherectomy (15), endarterectomy (10), and control non-atherosclerotic segments of renal (2) and of coronary and carotid (5) arteries, the extent of apoptosis was determined using TdT dUTP nick end labelling (TUNEL) and nuclear morphology (karyorrhexis/pyknosis) and expression of apoptosis regulators by immunohistochemistry and western blot analysis on paraffin-embedded material. In all specimens, the atherosclerotic involvement was advanced: grade V (n=18) and grade VI (n=7). The apoptotic index was high (mean 30%) in advanced lesions compared with controls (<2%) and smooth muscle cells (SMCs) were the predominant cell type undergoing apoptosis. In all TUNEL-positive apoptotic cells, Bax and Bak were present, while Bcl-x was absent. Bcl-2 was absent in a majority of these cells, but occasional TUNEL-positive cells expressed Bcl-2. In non-apoptotic cells, Bcl-x was present and western blot detected only the long isoform, Bcl-xL, from the plaques. In conclusion, increased Bax and Bak coupled with lack/paucity of Bcl-2 and Bcl-xL are associated with SMC apoptosis in advanced lesions. Bcl-xL in non-apoptotic cells appears to contribute to prolonged cell survival.
authors.affiliation: Department of Pathology, College of Medicine, University of Saskatchewan, c/o Royal University Hospital, 103 Hospital Drive, Saskatoon, Saskatchewan S7N 0W8, Canada. saxena@sask.usask.ca
authors.forename: A
authors.initials: A
authors.lastname: Saxena
authors.forename: J D
authors.initials: JD
authors.lastname: McMeekin
authors.forename: D J
authors.initials: DJ
authors.lastname: Thomson
mesh_terms: D017209:Apoptosis; D001161:Arteriosclerosis / Q000473:pathology*; D017225:Atherectomy, Coronary; D015415:Biomarkers / Q000032:analysis; D002339:Carotid Arteries / Q000473:pathology; D003331:Coronary Vessels / Q000473:pathology; D016894:Endarterectomy, Carotid; D006801:Humans; D020287:In Situ Nick-End Labeling; D008565:Membrane Proteins / Q000032:analysis*; D009130:Muscle, Smooth / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012077:Renal Artery / Q000473:pathology; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
chemical_list: C494772:BAK1 protein, human; C494826:BAX protein, human; C494811:BCL2L1 protein, human; D015415:Biomarkers; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein