Extended Data Figure 10: Treg cells require the LKB1–β-catenin signalling axis to enforce their functional fitness in maintaining immune homeostasis.
From: Homeostatic control of metabolic and functional fitness of Treg cells by LKB1 signalling
a, GSEA reveals the significant enrichment of the Wnt signalling gene set among the downregulated pathways in LKB1-deficient Treg cells. b, Relative expression of Ctnnb1 mRNA in activated wild-type and LKB1-deficient Treg cells. c, Expression of total and phosphorylated β-catenin in activated wild-type and LKB1-deficient Treg cells. Right, relative phosphorylation of β-catenin normalized by total β-catenin. d, ChIP and real-time PCR analysis of β-catenin-bound DNA of the Pdcd1 locus from activated Foxp3cre-ERT2Stk11fl/+ and Foxp3cre-ERT2Stk11fl/fl Treg cells (following in vivo tamoxifen treatment) (n = 4 each group). e, Mean fluorescence intensity (MFI) of GITR and CD25 expression on wild-type and Foxp3creStk11fl/fl Treg cells transduced with control retrovirus (RV) or mutant β-catenin-expressing retrovirus (β-cat-RV) (n = 3 each group). f, MFI of PD-1, GITR and CD25 expression on Foxp3cre-ERT2Stk11fl/+ (n = 5) and Foxp3cre-ERT2Stk11fl/fl (n = 4) Treg cells (following in vivo tamoxifen treatment) transduced with control RV or β-cat-RV. g, Expression of PD-L2, CD80 and CD86 on DCs co-cultured with wild-type or LKB1-deficient Treg cells transduced with RV or β-cat-RV. Numbers above graphs indicate the MFI. Data are representative of one (a) or two (b–g) independent experiments. Data are mean ± s.e.m. P values are determined by two-tailed Student’s t-test (d) or two-way ANOVA (e, f). NS, not significant; **P < 0.005, ***P < 0.0005. h, Schematics of LKB1 signalling in the regulation of Treg cell function and immune homeostasis. LKB1 signalling in Treg cells establishes metabolic and homeostatic fitness required for preventing undesired immune responses through selectively controlling the expression of inhibitory regulators, including PD-1, GITR and OX40. Consequently, uncontrolled expression of PD-1 and possible other receptors impairs the capability of Treg cells in suppressing TH2 immune responses triggered by TSLP-induced PD-L2+ DCs. Although not depicted here, IL-4 contributes to the induction of PD-L2 on DCs and the amplification of TH2-mediated immunopathology.
