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DNA-binding phosphoproteins induced after T cell activation: effects of cyclosporin A
1Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206, USA.
Abstract:
To define novel proteins involved in the early transcriptional response during the activation of human T lymphocytes, we used a high-resolution, two-dimensional gel electrophoresis system to identify nuclear, deoxyribonucleic acid (DNA) binding proteins exhibiting rapid changes in phosphorylation following cell stimulation. We identified 18 nuclear proteins whose phosphorylation level changed more than 5-fold upon activation. Of these, 11 were found to possess DNA-binding properties. The 11 phosphoproteins with DNA-binding activity, along with 4 others, were analyzed further. Phosphoamino acid analysis revealed several sets of proteins with different phosphorylated residues Kinetic analysis of the phosphorylation of the selected proteins was performed and revealed a complex group of transient and sustained responses to cell activation. Finally, the activation-induced changes in one set of phosphoproteins were dramatically inhibited by cyclosporin A. We suggest that these phosphoproteins may be directly involved in regulating the transcriptional response to cellular activation by external stimuli.
Insights
Researchers identified novel nuclear phosphoproteins involved in T lymphocyte activation. These DNA-binding proteins show altered phosphorylation, potentially regulating transcriptional responses to external stimuli.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- T lymphocyte activation is crucial for adaptive immunity.
- Understanding early transcriptional responses is key to controlling immune responses.
Purpose of the Study:
- To identify novel nuclear proteins involved in the early transcriptional response during human T lymphocyte activation.
- To characterize the phosphorylation status and DNA-binding properties of these proteins.
Main Methods:
- High-resolution, two-dimensional gel electrophoresis to identify nuclear proteins.
- Analysis of phosphorylation changes and DNA-binding properties.
- Phosphoamino acid analysis and kinetic studies of protein phosphorylation.
Main Results:
- Identified 18 nuclear proteins with >5-fold changes in phosphorylation upon activation.
- 11 of these proteins exhibited DNA-binding properties.
- Phosphorylation patterns revealed complex transient and sustained responses, with some inhibited by cyclosporin A.
Conclusions:
- Identified novel phosphoproteins involved in T lymphocyte activation.
- These DNA-binding proteins may play a direct role in regulating transcriptional responses to cellular activation.
- Cyclosporin A affects the phosphorylation of a subset of these proteins, suggesting a link to immune regulation pathways.