Chemical genetics to identify NFAT inhibitors: potential of targeting calcium mobilization in immunosuppression.
The development of more selective immunosuppressive agents to mitigate transplant rejection and autoimmune diseases requires effective strategies of blocking signaling pathways in T cells. Current immunosuppressive strategies use cyclosporin A (CsA) or FK506 to inhibit calcineurin, which dephosphorylates and promotes the nuclear import of nuclear factor of activated T cells (NFAT) transcription factors. These nuclear NFATs then transactivate cytokine genes that regulate proliferative responses of T cells. Both CsA and FK506 have debilitating side effects, including nephrotoxicity, hypertension, diabetes, and seizures, that argue for the development of alternative or complementary agents. To this end, we developed cell-based assays for monitoring NFAT dynamics in nonlymphoid cells to identify small molecules that inhibit NFAT nuclear import. Interestingly, we found that the majority of these small molecules suppress NFAT signaling by interfering with "capacitative" or "store-operated" calcium mobilization, thus raising the possibility that such mobilization processes are relevant targets in immunosuppression therapy. Further, these small molecules also show dose-dependent suppression of cytokine gene expression in T cells. Significantly, the IC(50) of CsA in primary T cells was reduced by the addition of suboptimal concentrations of these compounds, suggesting the possibility that such small molecules, in combination with CsA, offer safer means of immunosuppression.
Venkatesh
Natarajan
N
Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Feng
Yan
Y
DeDecker
Brian
B
Yacono
Patrick
P
Golan
David
D
Mitchison
Timothy
T
McKeon
Frank
F
D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D020650:Combinatorial Chemistry Techniques / Q000379:methods; D006224:Cricetinae; D016572:Cyclosporine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D007376:Interleukin-2 / Q000096:biosynthesis; D051379:Mice; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D009930:Organic Chemicals / Q000737:chemistry / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
D015220:Calcium Channels; D004268:DNA-Binding Proteins; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D009930:Organic Chemicals; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D016572:Cyclosporine; D019703:Calcineurin; D002118:Calcium