The nucleotide NAADP was recently discovered as a second messenger involved in the initiation and propagation of Ca(2+) signaling in lymphoma T cells, but its impact on primary T cell function is still unknown. An optimized, synthetic, small molecule inhibitor of NAADP action, termed BZ194, was designed and synthesized. BZ194 neither interfered with Ca(2+) mobilization by d-myo-inositol 1,4,5-trisphosphate or cyclic ADP-ribose nor with capacitative Ca(2+) entry. BZ194 specifically and effectively blocked NAADP-stimulated [(3)H]ryanodine binding to the purified type 1 ryanodine receptor. Further, in intact T cells, Ca(2+) mobilization evoked by NAADP or by formation of the immunological synapse between primary effector T cells and astrocytes was inhibited by BZ194. Downstream events of Ca(2+) mobilization, such as nuclear translocation of "nuclear factor of activated T cells" (NFAT), T cell receptor-driven interleukin-2 production, and proliferation in antigen-experienced CD4(+) effector T cells, were attenuated by the NAADP antagonist. Taken together, specific inhibition of the NAADP signaling pathway constitutes a way to specifically and effectively modulate T-cell activation and has potential in the therapy of autoimmune diseases.
Proc Natl Acad Sci U S A
10678 - 10683
Active Transport, Cell Nucleus, Animals, Binding, Competitive, Calcium, Calcium Signaling, Cell Nucleus, Cell Proliferation, Cells, Cultured, Dose-Response Relationship, Drug, Electrophoresis, Polyacrylamide Gel, Fluorescent Antibody Technique, Humans, Immunohistochemistry, Jurkat Cells, NADP, NFATC Transcription Factors, Niacin, Nicotinic Acids, Rats, Ryanodine, Ryanodine Receptor Calcium Release Channel, T-Lymphocytes, Tritium, Vitamin B Complex