Ca2+ release via ryanodine receptors and Ca2+ entry: major mechanisms in NAADP-mediated Ca2+ signaling in T-lymphocytes.
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent Ca2+ mobilizing nucleotide essentially involved in T cell activation. Using combined microinjection and single cell calcium imaging, we demonstrate that co-injection of NAADP and the D-myo-inositol 1,4,5-trisphosphate antagonist heparin did not inhibit Ca2+ mobilization. In contrast, co-injection of the ryanodine receptor antagonist ruthenium red efficiently blocked NAADP induced Ca2+ signalling. This pharmacological approach was confirmed using T cell clones stably transfected with plasmids expressing antisense mRNA targeted specifically against ryanodine receptors. NAADP induced Ca2+ signaling was strongly reduced in these clones. In addition, inhibition of Ca2+ entry by SK&F 96365 resulted in a dramatically decreased Ca2+ signal upon NAADP injection. Gd3+, a known blocker of Ca2+ release activated Ca2+ entry, only partially inhibited NAADP mediated Ca2+ signaling. These data indicate that in T cells (i) ryanodine receptor are the major intracellular Ca2+ release channels involved in NAADP induced Ca2+ signals, and that (ii) such Ca2+ release events are largely amplified by Ca2+ entry.
Langhorst
Matthias F
MF
Institute of Biochemistry and Molecular Biology I: Cellular Signal Transduction, University Hospital Hamburg-Eppendorf, Center of Experimental Medicine, Martinistr. 52, D-20246, Germany.
Schwarzmann
Nadine
N
Guse
Andreas H
AH
D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D005682:Gadolinium / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology*; D009249:NADP / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D016372:RNA, Antisense; D012430:Ruthenium Red / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014162:Transfection
D002121:Calcium Channel Blockers; D016372:RNA, Antisense; D019837:Ryanodine Receptor Calcium Release Channel; D012430:Ruthenium Red; D009249:NADP; C024376:NAADP; D015544:Inositol 1,4,5-Trisphosphate; D006493:Heparin; D005682:Gadolinium; D002118:Calcium