title: Ligand-dependent and -independent processes in B-cell-receptor-mediated signaling.
abstract: The B cell antigen receptor (BCR) is a protein complex expressed on the surface of immature and mature B cells. After ligand-induced aggregation, this complex generates signals that lead to a variety of biological outcomes, including survival, proliferation and differentiation. During B cell development intermediate forms of the BCR are expressed on the surface. The composition of these pro- and preBCR complexes reflects the ordered assembly of the BCR complex and they exist to generate signals for positive selection at defined developmental checkpoints. Because these receptors lack the ability to bind conventional ligands, the pro- and preBCR have been postulated to signal via ligand-independent processes. This ligand-independent or constitutive signal may also play a role in the survival of peripheral mature B cells. Here we discuss the evidence for ligand-independent functions for the BCR and postulate how it may be regulated and linked to biological processes associated with B cell development and survival.
authors.affiliation: University of Pennsylvania School of Medicine, Room 311 BRBII/III, 421 Curie Blvd., Philadelphia, PA 19104, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Fuentes-Pananá
authors.forename: J G
authors.initials: JG
authors.lastname: Monroe
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology; D002454:Cell Differentiation; D004254:DNA Nucleotidyltransferases / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D015322:Gene Rearrangement, B-Lymphocyte; D005803:Genes, Immunoglobulin; D006801:Humans; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D046911:Macromolecular Substances; D008322:Mammals / Q000276:immunology; D051379:Mice; D018448:Models, Immunological; D011947:Receptors, Antigen, B-Cell / Q000737:chemistry / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000276:immunology; D045567:VDJ Recombinases; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D008024:Ligands; D046911:Macromolecular Substances; D011947:Receptors, Antigen, B-Cell; D019061:src-Family Kinases; D004254:DNA Nucleotidyltransferases; D045567:VDJ Recombinases