| Project/Area Number |
03680166
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
代謝生物化学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
SHIMIZU Akira Kyoto Univ., Ctr. Mol. Biol. Genet., Professor, 遺伝子実験施設, 教授 (00162694)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1992: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Trans-splicing / Immunoglobulin Gene / Antibody Class Switching / Multiple Isotype Expression / P. C. R / Trans-mRNA / Transgenic Mouse |
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| Research Abstract |
We analyzed the molecular mechanism for the Ig multiple isotype expression using a transgenic mouse model system. Though most of the endogenous mu chain expression was excluded by the expression of the human rearranged mu transgene in TG.SA mouse, a significant portion of splenic B lymphocytes could express the transgenic human IgM and endogenous mouse IgG simultaneously after stimulation with LPS and IL-4. The FACS-purified population of the human IgM^+/mouse IgG^+ cells expressed mRNA which consisted of properly spliced sequences of the transgenic V_HDJ_H and the endogenous mouse C_<gamma> genes (trans-mRNA), together with the transgenic human mu mRNA and germline transcripts of the mouse C_<gamma> gene, without apparent rearrangement of the transgene. We also found that a lymphoma tumor, derived from the TG.SA mouse, expressed the trans-mRNA and the transgenic mu mRNA without DNA rearrangement in either the transgene or the endogenous mouse switch region. We further investigated regulation of trans-mRNA expression. Regulated expression of trans-mRNA was similar to but slightly different from that of class switching. All the endogenous isotypes that are the targets of class switching were expressed in the trans-mRNA after appropriate stimulation. We could also detect trans-mRNA expression in another transgenic mouse line which carries a rearranged mouse V_HDJ_H-C_<mu> gene. These results indicate that trans-mRNA synthesis is not restricted to either a particular transgenic line or an isotype, but is a general mechanism to express a second isotype with the V_H regions of rearranged mu chain transgenes. These findings strongly support that the trans-splicing can account for the Ig multiple isotype expression.
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