Second Messenger Function of Nicotinic Acid Adenine Dinucleotide Phosphate Revealed by an Improved Enzymatic Cycling Assay
2006 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 281, no 25, 16906-16913 p.Article in journal (Refereed) Published
Nicotinic acid adenine dinucleotide phosphate (NAADP) is the most potent activator of Ca2+ release from intracellular stores known today. Although recent reports have suggested an important function of NAADP in human T lymphocytes, direct evidence for receptor-induced formation of NAADP is yet missing in these cells. Thus, we developed a highly sensitive and specific enzyme assay capable of quantifying low fmol amounts of NAADP. In unstimulated T cells, the NAADP concentration amounted to 4.4 +/- 1.6 nm (0.055 +/- 0.028 pmol/mg of protein). Stimulation of the cells via the T cell receptor/CD3 complex resulted in biphasic elevation kinetics of cellular NAADP levels and was characterized by a bell-shaped concentration-response curve for NAADP. In contrast, the NAADP concentration was elevated neither upon activation of the ADP-ribose/TRPM2 channel Ca2+ signaling system nor by an increase of the intracellular Ca2+ concentration upon thapsigargin stimulation. T cell receptor/CD3 complex-mediated NAADP formation was dependent on the activity of tyrosine kinases because genistein completely blocked NAADP elevation. Thus, we propose a regulated formation of NAADP upon specific stimulation of the T cell receptor/CD3 complex, suggesting a function of NAADP as a Ca2+-mobilizing second messenger during T cell activation.
Place, publisher, year, edition, pages
American Society for Biochemistry and Molecular Biology, 2006. Vol. 281, no 25, 16906-16913 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-81990DOI: 10.1074/jbc.M601347200PubMedID: 16627475OAI: oai:DiVA.org:liu-81990DiVA: diva2:557234