title: Loss of the pro-apoptotic BH3-only Bcl-2 family member Bim sustains B lymphopoiesis in the absence of IL-7.
abstract: IL-7 is pivotal for B cell development. Proteins of the Bcl-2 family are essential regulators of lymphocyte survival. Particularly, the pro-apoptotic BH3-only members Bim and Puma mediate lymphocyte apoptosis provoked by cytokine deprivation. Herein, we addressed whether the absence of Bim or Puma within the hematopoietic compartment could bypass the requirement for IL-7-driven B cell development in adult mice. We found that deficiency of Bim, but not Puma, partially rescued B cell development in the absence of IL-7. The numbers of both sIgM(-) and sIgM(+) B cells were markedly increased in the bone marrow of recipients lacking IL-7 upon reconstitution with Bim-deficient hematopoietic progenitors, compared with their control or Puma-deficient counterparts. The augmentation of B cell lymphopoiesis in the absence of Bim was reflected in the mature peripheral compartment by an increase in both the number of immature and mature B cells in the spleen and in the circulating IgM levels. Bim-deficient B cells were also increased in IL-7-sufficient recipients suggesting that peripheral B cells homeostasis is governed by a Bim-dependent and IL-7-independent mechanism. Our data highlight the role of Bim as a key regulator of cell survival during B lymphocyte development in vivo.
authors.affiliation: Cytokines and Lymphoid Development Unit, Institut Pasteur, 25 rue du Docteur Roux, Paris, France.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Huntington
authors.forename: Verena
authors.initials: V
authors.lastname: Labi
authors.forename: Ana
authors.initials: A
authors.lastname: Cumano
authors.forename: Paulo
authors.initials: P
authors.lastname: Vieira
authors.forename: Andreas
authors.initials: A
authors.lastname: Strasser
authors.forename: Andreas
authors.initials: A
authors.lastname: Villunger
authors.forename: James P
authors.initials: JP
authors.lastname: Di Santo
authors.forename: Nuno L
authors.initials: NL
authors.lastname: Alves
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D000072224:Bcl-2-Like Protein 11; D001853:Bone Marrow / Q000254:growth & development / Q000276:immunology / Q000378:metabolism; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D015851:Interleukin-7 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D038041:Lymphopoiesis / Q000235:genetics / Q000276:immunology*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D004268:DNA-Binding Proteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015851:Interleukin-7; D008565:Membrane Proteins; C488588:PUMA protein, mouse; D011518:Proto-Oncogene Proteins; C499308:Rag2 protein, mouse; D025521:Tumor Suppressor Proteins