title: Thy28 partially prevents apoptosis induction following engagement of membrane immunoglobulin in WEHI-231 B lymphoma cells.
abstract: Thy28 protein is conserved among plants, bacteria, and mammalian cells. Nuclear Thy28 protein is substantially expressed in testis, liver, and immune cells such as lymphocytes. Lymphocyte apoptosis plays a crucial role in homeostasis and formation of a diverse lymphocyte repertoire. In this study, we examined whether Thy28 affects induction of apoptosis in WEHI-231 B lymphoma cells following engagement of membrane immunoglobulin (mIg). Once they were established, the Thy28-overexpressing WEHI-231 cells showed similar expression levels of IgM and class I major histocompatibility complex (MHC) molecule compared with controls. The Thy28-overexpressing cells were considerably resistant to loss of mitochondrial membrane potential (ΔΨm), caspase-3 activation, and increase in annexin-positive cells upon mIg engagement. These changes were concomitant with an increase in G1 phase associated with upregulation of p27(Kip1). The anti-IgM-induced sustained activation of c-Jun N-terminal kinase (JNK), which was associated with late-phase hydrogen peroxide (H(2)O(2)) production, was partially reduced in the Thy28-expressing cells relative to controls. Taken together, the data suggest that in WEHI-231 B lymphoma cells, Thy28 regulates mIg-mediated apoptotic events through the JNK-H(2)O(2) activation pathway, concomitant with an accumulation of cells in G1 phase associated with upregulation of p27(Kip1) in WEHI-231 B lymphoma cells.
authors.affiliation: Department of Immunology, Tokyo Medical University, Shinjuku-ku, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Toyota
authors.forename: Xiao-Zhou
authors.initials: XZ
authors.lastname: Jiang
authors.forename: Hideki
authors.initials: H
authors.lastname: Asakura
authors.forename: Junichiro
authors.initials: J
authors.lastname: Mizuguchi
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D016193:G1 Phase; D005805:Genes, MHC Class I / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism; D007136:Immunoglobulins / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D016393:Lymphoma, B-Cell / Q000378:metabolism / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D007136:Immunoglobulins; D009687:Nuclear Proteins; C470953:Thy28 protein, mouse; D050760:Cyclin-Dependent Kinase Inhibitor p27; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D053148:Caspase 3