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 lipopolisaccharide (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 α-chain (α(m)) to the synthesis of the secreted form of α-chain (α(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 α(m)-chains, whereas a smaller RNA molecule, 1.7 kb, encodes α(s). Analyses by RNA blotting showed that the relative amounts of the three α mRNA changed rapidly during LPS-induced differentiation. The amount of the 3.1 and 2.1 kb α mRNA decreased, and the amount of the 1.7 kb α(s) mRNA increased in LPS-stimulated cells as compared with controls. These observations suggest that the regulation of α(m)/α(s) synthesis is controlled mostly at the pretranslational level.
|Number of pages||6|
|Journal||Journal of Immunology|
|Publication status||Published - 1985|
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