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Synthesis and regulation of trans ‐mRNA encoding the immunoglobulin ∊ heavy chain
Author(s) -
Shimizu Akira,
Honjo Tasuku
Publication year - 1993
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.7.1.7916698
Subject(s) - isotype , immunoglobulin class switching , messenger rna , immunoglobulin heavy chain , microbiology and biotechnology , antibody , biology , exon , alternative splicing , germline , immunoglobulin light chain , rna splicing , gene , b cell , genetics , monoclonal antibody , rna
We have detected an immunoglobulin heavy‐chain trans ‐mRNA of the ∊ class in which the variable region of the human transgenic μ chain is correctly spliced to the first exon of the endogenous mouse ∊ constant region. Together with our previous observations, all the endogenous isotypes that are targets of class switching have proved to be expressed as trans ‐mRNA. This indicates that immunoglobulin trans ‐mRNA synthesis is a general mechanism to express a second heavy‐chain iso‐type with the variable region of the transgenic μ chain. Synthesis of ∊ trans ‐mRNA is regulated in a way similar to the trans ‐mRNAs of the γ subclasses or class switching to ∊, i.e, interleukin‐4 can induce the germline transcript of the ∊ constant region, but costimulation with lipopolysaccharide is necessary for ∊ trans ‐mRNA expression. The amount of ∊ trans ‐mRNA induced is similar to that of γ1 and higher than expected as judged from the rate of class switching to ∊. All these data are consistent with our previous hypothesis that trans ‐mRNA is synthesized by a trans ‐splicing mechanism and that this mechanism is involved in the simultaneous multipleisotype expression of immunoglobulin in a single B lymphocyte.— Shimizu, A., Honjo, T. Synthesis and regulation of trans ‐mRNA encoding the immunoglobulin ∊ heavy chain. FASEB J. 7: 149‐154; 1993.