title: The regulation of membrane-bound and secreted alpha-chain biosynthesis during the differentiation of the B cell lymphoma I.29.
abstract: The regulation of the synthesis of membrane-bound and secreted IgA was investigated in the murine B lymphoma I.29 during the differentiation from IgA-bearing lymphocytes to IgA-secreting cells, as caused by treatment with lipopolysaccharide (LPS). LPS induced a threefold to fivefold increase in the amount of IgA synthesized, and induced a shift from the synthesis of the membrane form of alpha-chain (alpha m) to the synthesis of the secreted form of alpha-chain (alpha s), resulting in a 60-fold increase in the amount of IgA secreted. In vitro translation of sucrose gradient-fractionated RNA indicated that two mRNA molecules, 3.1 and 2.1 kilobase pairs (kb), encode alpha m-chains, whereas a smaller RNA molecule, 1.7 kb, encodes alpha s. Analyses by RNA blotting showed that the relative amounts of the three alpha mRNA changed rapidly during LPS-induced differentiation. The amount of the 3.1 and 2.1 kb alpha mRNA decreased, and the amount of the 1.7 kb alpha s mRNA increased in LPS-stimulated cells as compared with controls. These observations suggest that the regulation of alpha m/alpha s synthesis is controlled mostly at the pretranslational level.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000276:immunology / Q000378:metabolism; D007070:Immunoglobulin A / Q000096:biosynthesis; D007071:Immunoglobulin A, Secretory / Q000096:biosynthesis; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis*; D007137:Immunoglobulin alpha-Chains / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008223:Lymphoma / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis; D011947:Receptors, Antigen, B-Cell / Q000096:biosynthesis*
chemical_list: D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D007143:Immunoglobulin Heavy Chains; D007137:Immunoglobulin alpha-Chains; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011947:Receptors, Antigen, B-Cell