Coevolutionary analysis of Forkhead box protein P3 and its physical binary interactors E3 ubiquitin-protein ligase CHIP, Zfp-90, and nuclear receptor ROR-α.

Forkhead box protein P3 (FOXP3) is known to orchestrate the development and maintenance of T regulatory cells, a cell population specialized in immune suppression and peripheral immune tolerance. FOXP3 activity is fine-tuned through its interaction with several protein-binding partners. By using IntAct database, we retrieved three physical binary interactors: E3 ubiquitin-protein ligase CHIP, Zfp-90, and nuclear receptor ROR-α. Coevolution clusters between FOXP3 and its interactors were identified with the use of iBIS2 algorithm, the iterative version of BIS/BIS2. Most of the coevolving pairs came from some species of monotremes and marsupials, as well as from a group of bats, thus suggesting that protein interactions of FOXP3 with its partners may be changed and/or modulated during mammalian speciation. Furthermore, our analysis would suggest the occurrence of a determinant role of FOXP3 in suppressing pregnancy alloreactions in placental mammals. Similarly, FOXP3, through its interaction with different protein interaction mechanisms, would explain the unique control of inflammatory response to infections in bats. By identifying several inter-protein clusters between the different protein pairs, our findings may provide a guide for new therapeutic approaches to modulate T regulatory suppression and/or enhance immune tolerance.