title: Nuclear factors in B lymphoma enhance splicing of mouse membrane-bound mu mRNA in Xenopus oocytes.
abstract: Regulation of the synthesis of membrane-bound and secreted immunoglobulin mu heavy chains at the level of RNA processing is an important element for B cell development. The precursor mu RNA is either polyadenylated at the upstream poly(A) site (for the secreted form) or spliced (for the membrane-bound form) in a mutually exclusive manner. When the mouse mu gene linked to the SV40/HSV-TK hybrid promoter was microinjected into Xenopus oocytes, the mu messenger RNA (mRNA) was altered by coinjection of nuclei of mouse surface IgM-bearing B-lymphoma cells to include the synthesis of the membrane-bound form. An increase in the membrane-bound form was not observed when nuclei of IgM-secreting hybridoma cells or fibroblast cells were coinjected. Deletion of the upstream poly(A) site did not eliminate the effect of B-lymphoma nuclei suggesting that membrane-specific splicing is stimulated. Further, splicing of other mu gene introns was not affected by coinjection of B-lymphoma nuclei. These results suggest that mature B cells contain one or more transacting nuclear factors that stimulate splicing specific for membrane-bound mu mRNA.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000648:ultrastructure; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000502:physiology*; D004274:DNA, Recombinant; D005260:Female; D006825:Hybridomas / Q000648:ultrastructure; D007075:Immunoglobulin M / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics*; D007438:Introns; D008223:Lymphoma / Q000276:immunology* / Q000648:ultrastructure; D051379:Mice; D008845:Microinjections; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000378:metabolism*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D014407:Tumor Cells, Cultured; D014981:Xenopus
chemical_list: D004274:DNA, Recombinant; D007075:Immunoglobulin M; D007148:Immunoglobulin mu-Chains; D012333:RNA, Messenger