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Detection of CD45iota mRNA in murine Th1 but not Th2 clones
K Tsujikawa1, Y Uchino, T Ichijo
1Department of Immunology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan. tujikawa@phs.osaka-u.ac.jp
Abstract:
CD45, a prototype of the receptor-like protein tyrosine phosphatase (PTPase) family, is one of the essential molecules in signal transduction through T cell receptors. Because at least 8 types of CD45 isoforms can potentially be produced by alternative mRNA splicing of exons 4, 5, and 6, the analyses at the transcription and protein levels of CD45 during the development and differentiation of T cells have been performed using RT-PCR and isoform-specific monoclonal antibodies, respectively. We report here that the ninth and smallest isoform of CD45, designated as CD45iota (CD45t), which is alternatively spiced from exons 4, 5, and 6 as well as exon 7, is present in the fetal thymus and splenic T cells of mice, and in murine Th1 clones, but not in Th2 clones. The expression of full-length CD45t mRNA as the functional CD45 PTPase was confirmed by RT-PCR analysis. Furthermore, the expression vector of CD45t was constructed, and its expression was detected in combination with anti-pan CD45 mAb and our newly established anti-LAR/CD45 PTPase domain mAb. These results suggested that CD45t might be an important isoform of CD45 for differentiation signaling of Th cells, and might be used as a marker to distinguish between Th1 and Th2 cells.
Insights
Researchers identified a new CD45 isoform, CD45iota (CD45t), crucial for T cell receptor signaling. This CD45t isoform is present in Th1 cells but absent in Th2 cells, suggesting its role in T helper cell differentiation.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- CD45 is a key protein tyrosine phosphatase (PTPase) in T cell receptor signaling.
- Alternative splicing of CD45 exons 4, 5, and 6 generates at least 8 known isoforms.
- Understanding CD45 isoform expression is vital for T cell development and differentiation.
Purpose of the Study:
- To identify and characterize novel CD45 isoforms involved in T cell signaling.
- To investigate the expression of a newly identified CD45 isoform, CD45iota (CD45t), in T cells.
- To explore the potential role of CD45t in distinguishing between Th1 and Th2 cell subsets.
Main Methods:
- Reverse Transcription Polymerase Chain Reaction (RT-PCR) for mRNA analysis.
- Isoform-specific monoclonal antibodies for protein detection.
- Construction and expression analysis of CD45t expression vector.
Main Results:
- A ninth, smaller CD45 isoform, CD45iota (CD45t), was identified, spliced from exons 4, 5, 6, and 7.
- CD45t expression was detected in fetal thymus, splenic T cells, and murine Th1 clones.
- CD45t was notably absent in Th2 clones, confirmed by RT-PCR and antibody detection.
Conclusions:
- CD45t represents a novel, functionally significant CD45 isoform.
- CD45t expression is linked to T helper cell differentiation.
- CD45t may serve as a valuable marker for differentiating Th1 and Th2 cells.