PDK1 Is Required for Maintenance of CD4⁺ Foxp3⁺ Regulatory T Cell Function

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Regulatory T (Treg) cells maintain immune homeostasis by suppressing effector T cells.
• Phosphoinositide-dependent kinase 1 (PDK1) is vital for T cell activation, proliferation, and cytokine production.
• PDK1 is a key kinase downstream of PI3K, regulating NF-κB and AKT signaling.

Purpose of the Study:

• To investigate the role of PDK1 in Treg cell function in vivo.
• To determine the molecular mechanisms by which PDK1 regulates Treg cell suppressive activity.

Main Methods:

• Treg cell-specific conditional deletion of the Pdk1 gene in mice.
• Analysis of inflammatory phenotypes and immune homeostasis.
• Genome-wide gene expression analysis.
• Investigation of NF-κB signaling pathway activation.

Main Results:

• Ablation of Pdk1 in Treg cells caused systemic, lethal, scurfy-like inflammation.
• PDK1 is essential for regulating key Treg cell signature gene expression.
• PDK1 primarily controls Treg cell gene expression through the canonical NF-κB pathway.
• The inflammatory phenotype was rescued by enforced NF-κB activation.

Conclusions:

• PDK1 is essential for Treg cell suppressive function in vivo.
• PDK1-mediated activation of the NF-κB pathway is critical for Treg cell signature gene expression and suppressor function.
• Targeting PDK1-NF-κB signaling could offer therapeutic strategies for immune dysregulation.