The regulation of membrane-bound and secreted alpha-chain biosynthesis during the differentiation of the B cell lymphoma I.29
Department of Molecular Genetics and Microbiology
Animals; B-Lymphocytes; Cell Line; Cell Transformation, Neoplastic; Immunoglobulin A; Immunoglobulin A, Secretory; Immunoglobulin Heavy Chains; Immunoglobulin alpha-Chains; Lipopolysaccharides; *Lymphocyte Activation; Lymphoma; Mice; RNA, Messenger; RNA, Neoplasm; Receptors, Antigen, B-Cell
Life Sciences | Medicine and Health Sciences | Women's Studies
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.
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Citation: J Immunol. 1985 Oct;135(4):2859-64.