title: Induction of autophagy by B cell antigen receptor stimulation and its inhibition by costimulation.
abstract: Autophagy is a major pathway for degradation of cytoplasmic components, and is induced by some apoptotic stimuli mostly in cancer cells under the condition in which apoptosis is blocked. Ligation of the B cell antigen receptor (BCR) induces apoptosis and plays a crucial role in self-tolerance. However, whether BCR ligation induces autophagy is not clear. Here, we demonstrate that autophagosomes are extensively formed in normal mouse B cells as well as the WEHI-231 B cell line upon induction of BCR ligation-induced apoptosis regardless of whether apoptosis is blocked by overexpression of Bcl-2. In contrast, autophagosomes were not formed during apoptosis of spleen B cells cultured with medium alone or in BCR-ligated BAL17 cells which do not undergo apoptosis. Moreover, autophagy is not induced when apoptotic BCR signaling is abrogated by CD40 signaling. These results indicate that autophagy is induced specifically by apoptotic BCR signaling even in unmanipulated normal B cells.
authors.affiliation: Laboratory of Immunology, School of Biomedical Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Kozo
authors.initials: K
authors.lastname: Watanabe
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.forename: Koji
authors.initials: K
authors.lastname: Hayashizaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsubata
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D017209:Apoptosis; D001343:Autophagy; D001402:B-Lymphocytes / Q000276:immunology*; D019013:CD40 Antigens / Q000037:antagonists & inhibitors; D002460:Cell Line; D007075:Immunoglobulin M / Q000276:immunology; D051379:Mice; D010588:Phagosomes / Q000276:immunology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000819:agonists* / Q000037:antagonists & inhibitors*
chemical_list: D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D007075:Immunoglobulin M; D019253:Proto-Oncogene Proteins c-bcl-2; D011947:Receptors, Antigen, B-Cell