title: IgM RNA switch from membrane to secretory form is prevented by adding antireceptor antibody to bacterial lipopolysaccharide-stimulated murine primary B-cell cultures.
abstract: Bacterial lipopolysaccharide (LPS) induces proliferation of resting primary murine B lymphocytes and their differentiation into Ig-secreting cells. This is accompanied by an increase in the rate of Ig gene transcription and the accumulation of mu heavy chain secretory mRNA. Specific antiantigen receptor antibody (anti-mu) induces resting B cells to proliferation but not differentiation. Upon addition of both LPS and anti-mu to cultures, resting B cells again proliferate but do not differentiate. RNA transfer blots of the Ig mRNA 2 days after induction with LPS/anti-mu show a specific deficiency of the 2.4-kilobase (kb) mu secretory mRNA, whereas the levels of the 2.7-kb mu membrane and 1.2-kb kappa light chain mRNAs are as high as in cells treated with LPS alone. Between days 3 and 4 after treatment with both reagents, reductions of mu membrane and, to a smaller extent, kappa mRNA become apparent. As measured by nuclear run-on transcription experiments at day 2, the transcription rates of Ig mu and the Ig kappa transcription units are equal in both induction experiments. Only at later stages do the LPS/anti-mu-treated cells transcribe Ig genes at a lower rate. Thus, the anti-mu treatment, drastically reducing the mu secretory mRNA production at early stages, represents a negative regulation occurring primarily at the posttranscriptional level.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007075:Immunoglobulin M / Q000235:genetics* / Q000378:metabolism; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D014158:Transcription, Genetic
chemical_list: D000906:Antibodies; D007140:Immunoglobulin Fab Fragments; D007075:Immunoglobulin M; D007145:Immunoglobulin kappa-Chains; D007148:Immunoglobulin mu-Chains; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011947:Receptors, Antigen, B-Cell; C033027:secretory IgM