title: Ligation of centrocyte/centroblast marker 1 on Epstein-Barr virus--transformed B lymphocytes induces cell death in a reactive oxygen species--dependent manner.
abstract: After primary infection of B cells with Epstein-Barr virus (EBV), infected B cells express several viral homologs of human genes that promote activation (LMP1 and CD40) or survival (BHRF and BCL2). EBV-infected B cells also express germinal center phenotype markers, such as CD77, PNA, CD95, and CD38. This transformation of B cells by EBV infection resembles normal B-cell activation and differentiation arising in the germinal center. In the present study, we found that EBV-transformed B cells expressed centrocyte/centroblast marker 1 (CM1), a possible marker of GC B cells and an inducer of their apoptosis. Moreover, ligation of CM1 on EBV-transformed B cells by immobilized anti-CM1 monoclonal antibody induced cell death. The ligation of CM1 immediately increased the generation of intracellular reactive oxygen species (ROS) and disrupted the mitochondrial membrane potential. Pretreatment with N-acetyl cystein (an ROS inhibitor) almost completely blocked this cell death, but Z-VAD-fmk (a caspase inhibitor) did not. We further investigated whether apoptosis-inducing factor (AIF) and endonuclease G (EndoG), which are both related to caspase-independent cell death, would be translocated to the nucleus during the ligation of CM1. We found that AIF and EndoG were released to the cytosplam but not translocated to the nucleus. Moreover, cytochalasin D, a cytoskeleton disruptor, rescued the cells from CM1-mediated cell death and blocked ROS generation. Therefore, it is conceivable that CM1 signaling might provoke cytoskeleton polymerization and trigger ROS generation. Taking these observations together, we conclude that the ligation of CM1 on EBV-transformed B cells can cause cell death via the ROS produced by F-actin polymerization in a caspase-independent manner, although this cell death might be unrelated to AIF and EndoG release from the mitochondria.
authors.affiliation: Department of Anatomy and Research Center for Women's Disease, Inje University College of Medicine, Busan, Republic of Korea.
authors.forename: Yeong Seok
authors.initials: YS
authors.lastname: Kim
authors.forename: Ga Bin
authors.initials: GB
authors.lastname: Park
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Choi
authors.forename: Oh Suk
authors.initials: OS
authors.lastname: Kwon
authors.forename: Hyun Keun
authors.initials: HK
authors.lastname: Song
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Kang
authors.forename: Young In
authors.initials: YI
authors.lastname: Kim
authors.forename: Wang Jae
authors.initials: WJ
authors.lastname: Lee
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Hur
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology / Q000502:physiology*; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D001402:B-Lymphocytes / Q000378:metabolism / Q000502:physiology* / Q000821:virology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism; D004854:Herpesvirus 4, Human; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000276:immunology; D008928:Mitochondria / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000199:Actins; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000975:Antioxidants; D051033:Apoptosis Inducing Factor; D061945:Caspase Inhibitors; D010718:Phosphatidylserines; D017382:Reactive Oxygen Species; D015638:Cytochalasin D; D045304:Cytochromes c; D004706:Endodeoxyribonucleases; C052391:endonuclease G; D020169:Caspases; D000111:Acetylcysteine