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IL-1β promotes Th17 differentiation by inducing alternative splicing of FOXP3.

Mailer RK, Joly AL, Liu S, Elias S, Tegner J, Andersson J - Sci Rep (2015)

Bottom Line: FOXP3 is not only expressed by Treg cells but is also transiently expressed when naïve T cells differentiate into Th17 cells.Forced splicing of FOXP3 into FOXP3Δ2Δ7 strongly favored Th17 differentiation in vitro.Our results demonstrate that alternative splicing of FOXP3 modulates T cell differentiation.

View Article: PubMed Central - PubMed

Affiliation: Translational Immunology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.

ABSTRACT
CD4(+)FOXP3(+) regulatory T (Treg) cells are essential for maintaining immunological self-tolerance. Treg cell development and function depend on the transcription factor FOXP3, which is present in several distinct isoforms due to alternative splicing. Despite the importance of FOXP3 in the proper maintenance of Treg cells, the regulation and functional consequences of FOXP3 isoform expression remains poorly understood. Here, we show that in human Treg cells IL-1β promotes excision of FOXP3 exon 7. FOXP3 is not only expressed by Treg cells but is also transiently expressed when naïve T cells differentiate into Th17 cells. Forced splicing of FOXP3 into FOXP3Δ2Δ7 strongly favored Th17 differentiation in vitro. We also found that patients with Crohn's disease express increased levels of FOXP3 transcripts lacking exon 7, which correlate with disease severity and IL-17 production. Our results demonstrate that alternative splicing of FOXP3 modulates T cell differentiation. These results highlight the importance of characterizing FOXP3 expression on an isoform basis and suggest that immune responses may be manipulated by modulating the expression of FOXP3 isoforms, which has broad implications for the treatment of autoimmune diseases.

No MeSH data available.


Related in: MedlinePlus

Activation and IL-1β regulate alternative splicing of FOXP3.Quantitative PCR was used to analyze: (a) fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated with plate bound α-CD3 and soluble α-CD28 and IL-2 for 18 hours relative to freshly isolated cells. (b-d) Fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated as above in the presence of 10 ng/ml IL-1β, IL-6 or TNF-α relative to cells activated without cytokines. (e) FOXP3ex1/2 (dark gray), FOXP3ex1/3 (gray), and FOXP3ex6/8 (white) transcripts in CD4+ T cells sorted for low, intermediate (int), and high (hi) expression of CD25. (a,b) Data are representative of four independent experiments and presented as mean ± SD. P < 0.05 was considered significant (two-tailed unpaired Student’s t test). (c) Data (n = 3 technical replicates) are presented as mean ± SD.
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f2: Activation and IL-1β regulate alternative splicing of FOXP3.Quantitative PCR was used to analyze: (a) fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated with plate bound α-CD3 and soluble α-CD28 and IL-2 for 18 hours relative to freshly isolated cells. (b-d) Fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated as above in the presence of 10 ng/ml IL-1β, IL-6 or TNF-α relative to cells activated without cytokines. (e) FOXP3ex1/2 (dark gray), FOXP3ex1/3 (gray), and FOXP3ex6/8 (white) transcripts in CD4+ T cells sorted for low, intermediate (int), and high (hi) expression of CD25. (a,b) Data are representative of four independent experiments and presented as mean ± SD. P < 0.05 was considered significant (two-tailed unpaired Student’s t test). (c) Data (n = 3 technical replicates) are presented as mean ± SD.

Mentions: Having determined that patients suffering from Crohn’s disease had an increased frequency of exon 7 splicing in FOXP3 mRNA, we went on to identify factors that modulate the alternative splicing of FOXP3 in human Treg cells. To examine whether activation of Treg cells altered the balance of FOXP3 isoforms we compared the expression of FOXP3 transcripts between freshly isolated Treg cells and Treg cells activated with anti-CD3 and IL-2. We observed that FOXP3ex1/2 and FOXP3ex1/3 mRNA, but not FOXP3ex6/8 mRNA, were upregulated upon activation (Fig. 2a). We reasoned that signals promoting immune responses might alter the splicing of FOXP3 mRNA molecules to modulate their proinflammatory actions. Therefore, we addressed whether proinflammatory cytokines could modify the expression of FOXP3 splice variants in Treg cells. The expression of amount of total FOXP3, FOXP3ex1/2 and FOXP3ex1/3 mRNA were unchanged in response to TCR stimulation regardless of the presence of IL-1β, IL-6 or TNF-α (Fig. 2b–d, data not shown). Interestingly, although FOXP3ex6/8 mRNA was unchanged in response to TCR stimulation combined with IL-6 or TNF-α (Fig. 2c–d), it was increased in response to TCR stimulation supplemented with IL-1β (Fig. 2b).


IL-1β promotes Th17 differentiation by inducing alternative splicing of FOXP3.

Mailer RK, Joly AL, Liu S, Elias S, Tegner J, Andersson J - Sci Rep (2015)

Activation and IL-1β regulate alternative splicing of FOXP3.Quantitative PCR was used to analyze: (a) fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated with plate bound α-CD3 and soluble α-CD28 and IL-2 for 18 hours relative to freshly isolated cells. (b-d) Fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated as above in the presence of 10 ng/ml IL-1β, IL-6 or TNF-α relative to cells activated without cytokines. (e) FOXP3ex1/2 (dark gray), FOXP3ex1/3 (gray), and FOXP3ex6/8 (white) transcripts in CD4+ T cells sorted for low, intermediate (int), and high (hi) expression of CD25. (a,b) Data are representative of four independent experiments and presented as mean ± SD. P < 0.05 was considered significant (two-tailed unpaired Student’s t test). (c) Data (n = 3 technical replicates) are presented as mean ± SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593960&req=5

f2: Activation and IL-1β regulate alternative splicing of FOXP3.Quantitative PCR was used to analyze: (a) fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated with plate bound α-CD3 and soluble α-CD28 and IL-2 for 18 hours relative to freshly isolated cells. (b-d) Fold induction of FOXP3 transcripts in CD4+CD25hiCD127low cells activated as above in the presence of 10 ng/ml IL-1β, IL-6 or TNF-α relative to cells activated without cytokines. (e) FOXP3ex1/2 (dark gray), FOXP3ex1/3 (gray), and FOXP3ex6/8 (white) transcripts in CD4+ T cells sorted for low, intermediate (int), and high (hi) expression of CD25. (a,b) Data are representative of four independent experiments and presented as mean ± SD. P < 0.05 was considered significant (two-tailed unpaired Student’s t test). (c) Data (n = 3 technical replicates) are presented as mean ± SD.
Mentions: Having determined that patients suffering from Crohn’s disease had an increased frequency of exon 7 splicing in FOXP3 mRNA, we went on to identify factors that modulate the alternative splicing of FOXP3 in human Treg cells. To examine whether activation of Treg cells altered the balance of FOXP3 isoforms we compared the expression of FOXP3 transcripts between freshly isolated Treg cells and Treg cells activated with anti-CD3 and IL-2. We observed that FOXP3ex1/2 and FOXP3ex1/3 mRNA, but not FOXP3ex6/8 mRNA, were upregulated upon activation (Fig. 2a). We reasoned that signals promoting immune responses might alter the splicing of FOXP3 mRNA molecules to modulate their proinflammatory actions. Therefore, we addressed whether proinflammatory cytokines could modify the expression of FOXP3 splice variants in Treg cells. The expression of amount of total FOXP3, FOXP3ex1/2 and FOXP3ex1/3 mRNA were unchanged in response to TCR stimulation regardless of the presence of IL-1β, IL-6 or TNF-α (Fig. 2b–d, data not shown). Interestingly, although FOXP3ex6/8 mRNA was unchanged in response to TCR stimulation combined with IL-6 or TNF-α (Fig. 2c–d), it was increased in response to TCR stimulation supplemented with IL-1β (Fig. 2b).

Bottom Line: FOXP3 is not only expressed by Treg cells but is also transiently expressed when naïve T cells differentiate into Th17 cells.Forced splicing of FOXP3 into FOXP3Δ2Δ7 strongly favored Th17 differentiation in vitro.Our results demonstrate that alternative splicing of FOXP3 modulates T cell differentiation.

View Article: PubMed Central - PubMed

Affiliation: Translational Immunology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.

ABSTRACT
CD4(+)FOXP3(+) regulatory T (Treg) cells are essential for maintaining immunological self-tolerance. Treg cell development and function depend on the transcription factor FOXP3, which is present in several distinct isoforms due to alternative splicing. Despite the importance of FOXP3 in the proper maintenance of Treg cells, the regulation and functional consequences of FOXP3 isoform expression remains poorly understood. Here, we show that in human Treg cells IL-1β promotes excision of FOXP3 exon 7. FOXP3 is not only expressed by Treg cells but is also transiently expressed when naïve T cells differentiate into Th17 cells. Forced splicing of FOXP3 into FOXP3Δ2Δ7 strongly favored Th17 differentiation in vitro. We also found that patients with Crohn's disease express increased levels of FOXP3 transcripts lacking exon 7, which correlate with disease severity and IL-17 production. Our results demonstrate that alternative splicing of FOXP3 modulates T cell differentiation. These results highlight the importance of characterizing FOXP3 expression on an isoform basis and suggest that immune responses may be manipulated by modulating the expression of FOXP3 isoforms, which has broad implications for the treatment of autoimmune diseases.

No MeSH data available.


Related in: MedlinePlus