Related Experiment Videos
A naturally occurring soluble isoform of murine Fas generated by alternative splicing
1Immunobiology Section, Yale University Medical School, New Haven, Connecticut 06510, USA.
Abstract:
We report a soluble isoform of mouse Fas, which is generated by alternative splicing of Fas mRNA to a newly identified exon located between exons 2 and 3 of the previously published Fas sequence. This splicing event creates a novel Fas transcript, Fas beta, with the potential to encode a truncated form of the extracellular domain, termed Fas B. In vitro, P815 mastocytoma cells transfected with Fas B become resistant to Fas ligand-induced apoptosis, and the resistance is mediated by a secreted product of the transfected cells. In vivo, Fas beta mRNA expression is correlated inversely with apoptosis among subsets of intrahepatic T lymphocytes, a cell population in which activation-induced T cell apoptosis occurs. We propose that Fas B is a new cytokine that acts physiologically to limit apoptosis induced by Fas ligand.
Insights
Researchers discovered a soluble mouse Fas isoform, Fas beta, generated by alternative splicing. This isoform, Fas B, confers resistance to Fas ligand-induced apoptosis, acting as a novel cytokine to limit cell death.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- The Fas receptor plays a critical role in regulating apoptosis, a key process in immune system homeostasis.
- Dysregulation of Fas-mediated apoptosis is implicated in various immune disorders.
Purpose of the Study:
- To identify and characterize novel isoforms of the mouse Fas receptor.
- To investigate the functional role of a newly identified soluble Fas isoform in apoptosis regulation.
Main Methods:
- Analysis of Fas mRNA splicing variants using molecular cloning techniques.
- In vitro studies involving transfection of P815 mastocytoma cells with the Fas B isoform.
- Assessment of apoptosis resistance in transfected cells and in vivo correlation with Fas beta mRNA expression in intrahepatic T lymphocytes.
Main Results:
- A novel alternative splicing event generates Fas beta mRNA, encoding a soluble Fas extracellular domain, termed Fas B.
- Cells expressing Fas B exhibit resistance to Fas ligand-induced apoptosis, mediated by a secreted factor.
- Fas beta mRNA expression inversely correlates with T cell apoptosis in intrahepatic lymphocytes.
Conclusions:
- Fas B represents a novel soluble isoform of the Fas receptor with implications for apoptosis regulation.
- Fas B functions as a cytokine that physiologically limits Fas ligand-induced apoptosis.
- This finding provides new insights into the mechanisms controlling T cell apoptosis and immune homeostasis.