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Foxp3 protein stability is regulated by cyclin-dependent kinase 2
Peter A Morawski1, Parul Mehra, Chunxia Chen
1Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania and The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
The Journal of Biological Chemistry
|July 16, 2013
Summary
Cyclin-dependent kinase 2 (CDK2) negatively regulates the stability and function of Foxp3, a key transcription factor for regulatory T cells (Treg). Mutating CDK phosphorylation sites on Foxp3 enhances Treg stability and anti-inflammatory capacity.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Foxp3 is essential for regulatory T cell (Treg) development and function, controlling autoimmunity.
- The regulation of Foxp3 activity by extracellular signals remains incompletely understood.
- Cyclin-dependent kinase (CDK) motifs are present in the Foxp3 structure.
Purpose of the Study:
- To investigate the role of CDK2 in regulating Foxp3 stability and function.
- To determine if CDK2-mediated phosphorylation affects Treg cell-mediated immune suppression.
Main Methods:
- Phosphorylation assays using CDK2/cyclin E and Foxp3 constructs.
- Site-directed mutagenesis of CDK phosphorylation sites (Ser/Thr to Alanine) in Foxp3.
- Analysis of Foxp3 stability, gene expression (CD25, IL2), Treg suppressive function in vitro, and amelioration of colitis in vivo.
Main Results:
- CDK2, partnered with cyclin E, phosphorylates Foxp3 at specific motifs.
- Mutating these phosphorylation sites (S/T→A) enhances Foxp3 protein stability in CD4+ T cells.
- Mutant Foxp3-expressing T cells show enhanced gene regulation, increased suppressive capacity in vitro, and improved colitis amelioration in vivo.
Conclusions:
- CDK2 negatively regulates Foxp3 stability and activity.
- CDK-mediated phosphorylation of Foxp3 is a critical mechanism controlling Treg function.
- Targeting CDK-coupled signaling pathways may offer therapeutic strategies for inflammatory diseases.
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