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CD8 beta chain influences CD8 alpha chain-associated Lck kinase activity
H Y Irie1, K S Ravichandran, S J Burakoff
1Division of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
The Journal of Experimental Medicine
|April 1, 1995
Summary
The CD8 beta chain significantly enhances CD8 signaling by increasing Lck tyrosine kinase activity and protein phosphorylation. This highlights CD8 beta
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- The CD8 molecule is crucial for CD8+ T cell differentiation and function.
- CD8 exists as alpha alpha homodimers and alpha beta heterodimers.
- The CD8 beta chain's role in T cell signaling is not fully understood.
Purpose of the Study:
- To investigate how the CD8 beta chain influences CD8 signaling.
- To compare the signaling capabilities of CD8 alpha alpha and CD8 alpha beta.
Main Methods:
- Introduced the CD8 beta gene into a T cell hybridoma expressing CD8 alpha alpha.
- Analyzed Lck tyrosine kinase activity and intracellular protein phosphorylation.
- Assessed Lck association with CD8 alpha upon CD8 cross-linking.
Main Results:
- CD8 beta coexpression led to a 10-fold increase in Lck kinase activity upon CD8 cross-linking.
- Enhanced tyrosine phosphorylation of intracellular proteins was observed in CD8 alpha beta cells.
- CD8 beta stabilized Lck association with CD8 alpha.
Conclusions:
- The CD8 beta chain differentially modulates CD8 alpha-associated Lck tyrosine kinase activity.
- Distinct signaling pathways mediated by CD8 alpha alpha and CD8 alpha beta contribute to T cell development.
- These signaling differences may explain thymocyte development defects in CD8 beta-deficient mice.