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Allelic exclusion at the TCRbeta locus.
Bernard Khor1, Barry P Sleckman
1Washington University School of Medicine, Department of Pathology and Immunology, 660 South Euclid Avenue, Campus Box 8118, St. Louis, MO 63110-1093, USA. Khorb@medicine.wustl.edu
Current Opinion in Immunology
|March 1, 2002
Summary
T-cell receptor (TCR) beta gene assembly is controlled by epigenetic changes and signaling pathways. These mechanisms ensure T-cell receptor allelic exclusion, crucial for immune system function.
Area of Science:
- Immunology
- Molecular Biology
- Epigenetics
Background:
- T-cell receptor (TCR) beta chain variable-region gene assembly is tightly regulated.
- Allelic exclusion ensures that only one TCRbeta allele is expressed per cell.
- Early epigenetic modifications and pre-TCR signaling are implicated in this process.
Purpose of the Study:
- To investigate the regulatory mechanisms governing TCRbeta allelic exclusion.
- To understand the role of epigenetic modifications in ordering TCRbeta allele rearrangement.
- To elucidate the signaling pathways involved in enforcing allelic exclusion.
Main Methods:
- Analysis of epigenetic modifications in TCRbeta alleles during thymocyte development.
- Investigation of pre-TCR signaling pathways, including p56(lck) and SLP-76.
- Assessment of Vbeta and D/Jbeta gene segment accessibility in thymocytes.
Main Results:
- Differential epigenetic modifications on TCRbeta alleles may dictate rearrangement order.
- Pre-TCR complex signaling, involving p56(lck) and SLP-76, enforces allelic exclusion in double-positive thymocytes.
- Changes in Vbeta gene segment accessibility, regulated by cis-acting elements, contribute to allelic exclusion.
Conclusions:
- Epigenetic regulation and pre-TCR signaling are critical for establishing TCRbeta allelic exclusion.
- Distinct signaling pathways may mediate allelic exclusion compared to other pre-TCR functions.
- Specific cis-acting elements regulate accessibility of Vbeta segments for TCRbeta allelic exclusion.