title: Deregulation of c-Myc Confers distinct survival requirements for memory B cells, plasma cells, and their progenitors.
abstract: Deregulation of the c-Myc oncogene is tightly associated with human and murine plasma cell (PC) neoplasms. Through the analysis of Ag-specific B cell responses in mice where Myc is targeted to the Igh Calpha locus, we show here that c-Myc dramatically impairs the primary and secondary Ab response. This impairment is differentiation stage specific, since germinal center B cell formation, affinity maturation, and class switch recombination were intact. Examination of PC viability revealed that c-Myc triggered apoptosis only upon final maturation when Ab is secreted and is resistant to the survival factor BAFF (B cell-activating factor belonging to the TNF family). In contrast, PC precursors (PC(pre)) that ultimately give rise to mature PCs survived normally and vigorously expanded with BAFF signaling. We further show that c-Myc also facilitates the apoptosis of memory B cells. Thus, Calpha-Myc controls both cellular arms of long-lived B cell immunity than previously anticipated. Only when deregulation of c-Myc was combined with enforced Bcl-x(L) expression were mature PCs able to survive in response to BAFF. These data indicate that the survival requirements for tumor-susceptible PC(pre) and PCs are distinct and that tumor progression likely develops as PC(pre) transition to functional PCs when apoptotic pathways such as members of the Bcl-2 family are disabled.
authors.affiliation: Department of Microbiology, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Sefat E
authors.initials: SE
authors.lastname: Khuda
authors.forename: William M
authors.initials: WM
authors.lastname: Loo
authors.forename: Siegfried
authors.initials: S
authors.lastname: Janz
authors.forename: Brian
authors.initials: B
authors.lastname: Van Ness
authors.forename: Loren D
authors.initials: LD
authors.lastname: Erickson
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000235:genetics / Q000276:immunology; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D053264:B-Cell Activating Factor / Q000235:genetics / Q000276:immunology; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D018390:Gene Targeting / Q000379:methods; D018858:Germinal Center / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D014411:Neoplastic Stem Cells / Q000276:immunology / Q000473:pathology; D010950:Plasma Cells / Q000276:immunology*; D010954:Plasmacytoma / Q000235:genetics / Q000276:immunology; D054448:Precursor Cells, B-Lymphoid / Q000276:immunology*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000276:immunology*; D040641:Quantitative Trait Loci / Q000235:genetics / Q000276:immunology; D027041:Somatic Hypermutation, Immunoglobulin / Q000235:genetics / Q000276:immunology; D051020:bcl-X Protein / Q000235:genetics / Q000276:immunology
chemical_list: D053264:B-Cell Activating Factor; C494812:Bcl2l1 protein, mouse; C489427:MYC protein, human; C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; C505720:Tnfsf13b protein, mouse; D051020:bcl-X Protein