Inhibiting the calcineurin-NFAT (nuclear factor of activated T cells) signaling pathway with a regulator of calcineurin-derived peptide without affecting general calcineurin phosphatase activity.
Calcineurin phosphatase plays a crucial role in T cell activation. Dephosphorylation of the nuclear factors of activated T cells (NFATs) by calcineurin is essential for activating cytokine gene expression and, consequently, the immune response. Current immunosuppressive protocols are based mainly on calcineurin inhibitors, cyclosporine A and FK506. Unfortunately, these drugs are associated with severe side effects. Therefore, immunosuppressive agents with higher selectivity and lower toxicity must be identified. The immunosuppressive role of the family of proteins regulators of calcineurin (RCAN, formerly known as DSCR1) which regulate the calcineurin-NFAT signaling pathway, has been described recently. Here, we identify and characterize the minimal RCAN sequence responsible for the inhibition of calcineurin-NFAT signaling in vivo. The RCAN-derived peptide spanning this sequence binds to calcineurin with high affinity. This interaction is competed by a peptide spanning the NFAT PXIXIT sequence, which binds to calcineurin and facilitates NFAT dephosphorylation and activation. Interestingly, the RCAN-derived peptide does not inhibit general calcineurin phosphatase activity, which suggests that it may have a specific immunosuppressive effect on the calcineurin-NFAT signaling pathway. As such, the RCAN-derived peptide could either be considered a highly selective immunosuppressive compound by itself or be used as a new tool for identifying innovative immunosuppressive agents. We developed a low throughput assay, based on the RCAN1-calcineurin interaction, which identifies dipyridamole as an efficient in vivo inhibitor of the calcineurin-NFAT pathway that does not affect calcineurin phosphatase activity.
Mulero
Ma Carme
MC
Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Gran Via s/n Km. 2.7, 08907 L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
Aubareda
Anna
A
Orzáez
Mar
M
Messeguer
Joaquim
J
Serrano-Candelas
Eva
E
Martínez-Hoyer
Sergio
S
Messeguer
Angel
A
Pérez-Payá
Enrique
E
Pérez-Riba
Mercè
M
D000595:Amino Acid Sequence; D000818:Animals; D019703:Calcineurin / Q000378:metabolism*; D002460:Cell Line; D002522:Chlorocebus aethiops; D004176:Dipyridamole / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D050778:NFATC Transcription Factors / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction / Q000187:drug effects
D047908:Intracellular Signaling Peptides and Proteins; D050778:NFATC Transcription Factors; D010446:Peptide Fragments; D004176:Dipyridamole; C120817:calcineurin phosphatase; D019703:Calcineurin; D010744:Phosphoric Monoester Hydrolases