title: Role of c-myc and CD45 in spontaneous and anti-receptor-induced apoptosis in adult murine B cells.
abstract: Although adult murine B cells can be stimulated to proliferate by Igm receptor cross-linking, we and others have shown that these cells will undergo apoptosis in vitro in a dose-, time- and temperature-dependent manner with polyclonal but not monoclonal anti-IgM, To test the role of c-myc and cell cycle progression in B cell apoptosis, we examined normal, Sp6 anti-TNP lg and E micro-myc transgenic splenocytes for receptor-mediated apoptosis in vitro. In normal mice, both spontaneous and anti-IgM-induced programmed cell death were specifically blocked by antisense oligodeoxynucleotides for the c-myc proto-oncogene, whereas nonsense myc oligonucleotides and irrelevant oligonucleotides had only a minor effect. Similarly, TNP-dextran-induced apoptosis in Sp6 anti-TNF transgenics was inhibited by antisense c-myc. This effect was not due to the mitogenic effects of unmethylated CpG-containing sequences because ones lacking this motif, as well as methylated oligonucleotides containing this motif, prevented apoptosis, and mitogenic doses of lipopolysaccharide failed to inhibit anti-IgM-driven cell death. Importantly, antisense c-myc also prevented the anti-IgM-induced increase in myc protein species. Moreover, spontaneous apoptosis in vitro was exaggerated in E micro-myc transgenic B cells. To examine the role of CD45 in anti-IgM-induced apoptosis, we treated spleen cells from CD45 knockout mice, which do not proliferate with anti-IgM, and found that B cells from these underwent apoptosis normally despite the lack of entry into S. These data suggest that anti-IgM driven apoptosis does not require CD45. Rather, apoptosis may be due to an overexpression of myc protein in the absence of signals which can drive B cells productively into S, but the failure to proliferate normally is insufficient for apoptosis to occur.
authors.affiliation: Immunology Department, American Red Cross Holland Laboratory, Rockville, MD 20855, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Scott
authors.forename: M
authors.initials: M
authors.lastname: Lamers
authors.forename: G
authors.initials: G
authors.lastname: Köhler
authors.forename: C L
authors.initials: CL
authors.lastname: Sidman
authors.forename: B
authors.initials: B
authors.lastname: Maddox
authors.forename: R
authors.initials: R
authors.lastname: Carsetti
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D002453:Cell Cycle; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D016259:Genes, myc; D007152:Immunologic Capping; D017493:Leukocyte Common Antigens / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D014157:Transcription Factors
chemical_list: D000888:Antibodies, Anti-Idiotypic; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D008070:Lipopolysaccharides; C067850:Myc associated factor X; D016376:Oligonucleotides, Antisense; D016271:Proto-Oncogene Proteins c-myc; D014157:Transcription Factors; C044203:anti-IgM; C068422:Max protein, mouse; D017493:Leukocyte Common Antigens