| First Author | Almahariq M | Year | 2015 |
| Journal | Biochem J | Volume | 465 |
| Issue | 2 | Pages | 295-303 |
| PubMed ID | 25339598 | Mgi Jnum | J:218535 |
| Mgi Id | MGI:5617889 | Doi | 10.1042/BJ20140952 |
| Citation | Almahariq M, et al. (2015) Exchange protein directly activated by cAMP modulates regulatory T-cell-mediated immunosuppression. Biochem J 465(2):295-303 |
| abstractText | The cAMP signalling pathway plays an essential role in immune functions. In the present study we examined the role of the cAMP/EPAC1 (exchange protein directly activated by cAMP) axis in regulatory T-cell (Treg)-mediated immunosuppression using genetic and pharmacological approaches. Genetic deletion of EPAC1 in Tregs and effector T-cells (Teffs) synergistically attenuated Treg-mediated suppression of Teffs. Mechanistically, EPAC1 inhibition enhanced activation of the transcription factor STAT3 (signal transducer and activator of transcription 3) and up-regulated SMAD7 expression while down-regulating expression of SMAD4. Consequently, CD4+ T-cells were desensitized to transforming growth factor (TGF) beta1, a cytokine employed by Tregs to exert a broad inhibitory function within the immune system. Furthermore, deletion of EPAC1 led to production of significant levels of ovalbumin IgG antibodies in a low-dose, oral-tolerance mouse model. These in vivo observations are consistent with the finding that EPAC1 plays an important role in Treg-mediated suppression. More importantly, pharmacological inhibition of EPAC1 using an EPAC-specific inhibitor recapitulates the EPAC1 deletion phenotype both in vivo and in vitro. The results of the present study show that EPAC1 boosts Treg-mediated suppression, and identifies EPAC1 as a target with broad therapeutic potential because Tregs are involved in numerous pathologies, including autoimmunity, infections and a wide range of cancers. |
