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USP21 prevents the generation of T-helper-1-like Treg cells

View Article: PubMed Central - PubMed

ABSTRACT

FOXP3+ Regulatory T (Treg) cells play a key role in the maintenance of immune homeostasis and tolerance. Disruption of Foxp3 expression results in the generation of instable Treg cells and acquisition of effector T-cell-like function. Here we report that the E3 deubiquitinase USP21 prevents the depletion of FOXP3 at the protein level and restricts the generation of T-helper-1-like Treg cells. Mice depleted of Usp21 specifically in Treg cells display immune disorders characterized by spontaneous T-cell activation and excessive T-helper type 1 (Th1) skewing of Treg cells into Th1-like Treg cells. USP21 stabilizes FOXP3 protein by mediating its deubiquitination and maintains the expression of Treg signature genes. Our results demonstrate how USP21 prevents FOXP3 protein depletion and controls Treg lineage stability in vivo.

No MeSH data available.


Usp21fl/flFoxp3Cre mice develop spontaneous lymphoproliferative disease.(a) CD4+CD25−YFP− effector T (Teff) cells and CD4+CD25hiYFP+ Treg cells were sorted from Foxp3Cre (WT) and Usp21fl/flFoxp3Cre (KO) mice. mRNA expression of Usp21 in each population was assessed by qRT–PCR. (n=3 for each group). (b) Image of spleens and peripheral lymph nodes (pLNs) from 8-month-old WT and KO mice. (c) Quantitative analysis of the weight of spleens isolated from WT (n=5) and KO (n=5) mice. (d) Representative figure shown the expression of CD62L and CD44 in splenic CD4+YFP− and CD8+ T cells from WT (n=7) and KO (n=7) littermates. (e) Percentage of splenic CD62LloCD44hi effector memory T cells as in d. (f) Representative figure shown the expression of IFN-γ, IL-17, IL-2 and IL-4 by splenic CD4+YFP− effector T (Teff) cells from WT (n=5) and KO (n=5) mice. (g) Percentage of IFN-γ+, IL-17+, IL-2+ and IL-4+ splenic T cells as in f. Small horizontal lines indicate the mean (±s.d.). All data represent means±s.d. **P≤0.01, as determined by Student's t-test.
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f1: Usp21fl/flFoxp3Cre mice develop spontaneous lymphoproliferative disease.(a) CD4+CD25−YFP− effector T (Teff) cells and CD4+CD25hiYFP+ Treg cells were sorted from Foxp3Cre (WT) and Usp21fl/flFoxp3Cre (KO) mice. mRNA expression of Usp21 in each population was assessed by qRT–PCR. (n=3 for each group). (b) Image of spleens and peripheral lymph nodes (pLNs) from 8-month-old WT and KO mice. (c) Quantitative analysis of the weight of spleens isolated from WT (n=5) and KO (n=5) mice. (d) Representative figure shown the expression of CD62L and CD44 in splenic CD4+YFP− and CD8+ T cells from WT (n=7) and KO (n=7) littermates. (e) Percentage of splenic CD62LloCD44hi effector memory T cells as in d. (f) Representative figure shown the expression of IFN-γ, IL-17, IL-2 and IL-4 by splenic CD4+YFP− effector T (Teff) cells from WT (n=5) and KO (n=5) mice. (g) Percentage of IFN-γ+, IL-17+, IL-2+ and IL-4+ splenic T cells as in f. Small horizontal lines indicate the mean (±s.d.). All data represent means±s.d. **P≤0.01, as determined by Student's t-test.

Mentions: To illustrate the function of USP21 in controlling Treg-cell fate in vivo, we developed a mouse model where Usp21 is depleted only in Treg cells (Usp21fl/flFoxp3Cre mice) by crossing Usp21fl/fl mice with mice bearing YFP-fused Cre recombinase under control of the Foxp3 gene locus (Fig. 1a). We first analysed thymic development of CD4+ and CD8+ T cells, and no significant difference was observed between Foxp3Cre and Usp21fl/flFoxp3Cre mice (Supplementary Fig. 1a,b). Meanwhile, we did not find significant changes in the absolute numbers of CD4+CD8− (CD4-SP), CD4−CD8+ (CD8-SP), CD4−CD8− (DN) and CD4+CD8+ (DP) thymocytes in Usp21fl/flFoxp3Cre mice (Supplementary Fig. 1c). Usp21fl/flFoxp3Cre mice developed lymphadenopathy and splenomegaly at the age of 6 to 8 months (Fig. 1b,c), suggesting aberrant immune activation. We next tested whether Treg-specific deletion of Usp21 perturbed T-cell activation and homeostasis. We observed increased frequency of CD62LloCD44hi effector memory T cells in Usp21fl/flFoxp3Cre mice (Fig. 1d,e). We also observed excessive Th1 responses in Usp21fl/flFoxp3Cre mice, where splenic CD4+YFP− effector T cells (Teff) produced higher levels of interferon (IFN)-γ on in vitro stimulation (Fig. 1f,g). Therefore, USP21-deficient Treg cells failed to maintain immune tolerance and the related inflammation in vivo.


USP21 prevents the generation of T-helper-1-like Treg cells
Usp21fl/flFoxp3Cre mice develop spontaneous lymphoproliferative disease.(a) CD4+CD25−YFP− effector T (Teff) cells and CD4+CD25hiYFP+ Treg cells were sorted from Foxp3Cre (WT) and Usp21fl/flFoxp3Cre (KO) mice. mRNA expression of Usp21 in each population was assessed by qRT–PCR. (n=3 for each group). (b) Image of spleens and peripheral lymph nodes (pLNs) from 8-month-old WT and KO mice. (c) Quantitative analysis of the weight of spleens isolated from WT (n=5) and KO (n=5) mice. (d) Representative figure shown the expression of CD62L and CD44 in splenic CD4+YFP− and CD8+ T cells from WT (n=7) and KO (n=7) littermates. (e) Percentage of splenic CD62LloCD44hi effector memory T cells as in d. (f) Representative figure shown the expression of IFN-γ, IL-17, IL-2 and IL-4 by splenic CD4+YFP− effector T (Teff) cells from WT (n=5) and KO (n=5) mice. (g) Percentage of IFN-γ+, IL-17+, IL-2+ and IL-4+ splenic T cells as in f. Small horizontal lines indicate the mean (±s.d.). All data represent means±s.d. **P≤0.01, as determined by Student's t-test.
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f1: Usp21fl/flFoxp3Cre mice develop spontaneous lymphoproliferative disease.(a) CD4+CD25−YFP− effector T (Teff) cells and CD4+CD25hiYFP+ Treg cells were sorted from Foxp3Cre (WT) and Usp21fl/flFoxp3Cre (KO) mice. mRNA expression of Usp21 in each population was assessed by qRT–PCR. (n=3 for each group). (b) Image of spleens and peripheral lymph nodes (pLNs) from 8-month-old WT and KO mice. (c) Quantitative analysis of the weight of spleens isolated from WT (n=5) and KO (n=5) mice. (d) Representative figure shown the expression of CD62L and CD44 in splenic CD4+YFP− and CD8+ T cells from WT (n=7) and KO (n=7) littermates. (e) Percentage of splenic CD62LloCD44hi effector memory T cells as in d. (f) Representative figure shown the expression of IFN-γ, IL-17, IL-2 and IL-4 by splenic CD4+YFP− effector T (Teff) cells from WT (n=5) and KO (n=5) mice. (g) Percentage of IFN-γ+, IL-17+, IL-2+ and IL-4+ splenic T cells as in f. Small horizontal lines indicate the mean (±s.d.). All data represent means±s.d. **P≤0.01, as determined by Student's t-test.
Mentions: To illustrate the function of USP21 in controlling Treg-cell fate in vivo, we developed a mouse model where Usp21 is depleted only in Treg cells (Usp21fl/flFoxp3Cre mice) by crossing Usp21fl/fl mice with mice bearing YFP-fused Cre recombinase under control of the Foxp3 gene locus (Fig. 1a). We first analysed thymic development of CD4+ and CD8+ T cells, and no significant difference was observed between Foxp3Cre and Usp21fl/flFoxp3Cre mice (Supplementary Fig. 1a,b). Meanwhile, we did not find significant changes in the absolute numbers of CD4+CD8− (CD4-SP), CD4−CD8+ (CD8-SP), CD4−CD8− (DN) and CD4+CD8+ (DP) thymocytes in Usp21fl/flFoxp3Cre mice (Supplementary Fig. 1c). Usp21fl/flFoxp3Cre mice developed lymphadenopathy and splenomegaly at the age of 6 to 8 months (Fig. 1b,c), suggesting aberrant immune activation. We next tested whether Treg-specific deletion of Usp21 perturbed T-cell activation and homeostasis. We observed increased frequency of CD62LloCD44hi effector memory T cells in Usp21fl/flFoxp3Cre mice (Fig. 1d,e). We also observed excessive Th1 responses in Usp21fl/flFoxp3Cre mice, where splenic CD4+YFP− effector T cells (Teff) produced higher levels of interferon (IFN)-γ on in vitro stimulation (Fig. 1f,g). Therefore, USP21-deficient Treg cells failed to maintain immune tolerance and the related inflammation in vivo.

View Article: PubMed Central - PubMed

ABSTRACT

FOXP3+ Regulatory T (Treg) cells play a key role in the maintenance of immune homeostasis and tolerance. Disruption of Foxp3 expression results in the generation of instable Treg cells and acquisition of effector T-cell-like function. Here we report that the E3 deubiquitinase USP21 prevents the depletion of FOXP3 at the protein level and restricts the generation of T-helper-1-like Treg cells. Mice depleted of Usp21 specifically in Treg cells display immune disorders characterized by spontaneous T-cell activation and excessive T-helper type 1 (Th1) skewing of Treg cells into Th1-like Treg cells. USP21 stabilizes FOXP3 protein by mediating its deubiquitination and maintains the expression of Treg signature genes. Our results demonstrate how USP21 prevents FOXP3 protein depletion and controls Treg lineage stability in vivo.

No MeSH data available.