Lkb1 maintains T_reg cell lineage identity

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Regulatory T (Treg) cells are essential for immune homeostasis, characterized by Foxp3 expression and suppressor function.
• The upstream factors preserving Treg cell lineage identity remain largely unknown.

Purpose of the Study:

• To investigate the role of Liver kinase B1 (Lkb1) in maintaining Treg cell lineage identity and function.
• To elucidate the molecular mechanisms by which Lkb1 preserves Treg cell features.

Main Methods:

• T-cell receptor (TCR) stimulation assays.
• Generation of mice with Treg cell-specific Lkb1 deletion.
• Analysis of Foxp3 expression, DNA methylation, and gene expression in Treg cells.
• Assessment of autoimmune disease development in Lkb1-deficient mice.

Main Results:

• Lkb1 protein expression is upregulated in Treg cells upon TCR stimulation.
• Treg cell-specific deletion of Lkb1 results in fatal early-onset autoimmune disease.
• Lkb1 deficiency leads to loss of Foxp3 expression and impaired suppressor function in Treg cells.
• Lkb1 prevents STAT4-mediated methylation of the Foxp3 CNS2 locus, stabilizing Foxp3 expression.
• Lkb1 augments TGF-β signaling to promote immunosuppressive gene expression, independent of Foxp3 stabilization.

Conclusions:

• Lkb1 is a critical factor for maintaining Treg cell lineage identity and function.
• Lkb1 safeguards Treg cell suppressive capacity by stabilizing Foxp3 expression and programming immunosuppressive genes.
• Lkb1 acts as a key regulator in preventing autoimmune diseases by preserving Treg cell integrity.