Second Messenger Function of Nicotinic Acid Adenine Dinucleotide Phosphate Revealed by an Improved Enzymatic Cycling Assay

Gasser, AndreasUniversity Medical Center Hamburg-Eppendorf, Germany (författare)

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.

Bruhn, Sören,1976-University Medical Center Hamburg-Eppendorf, Germany(Swepub:liu)sorbr27 (författare)
Guse, AndreasUniversity Medical Center Hamburg-Eppendorf, Germany (författare)
University Medical Center Hamburg-Eppendorf, Germany (creator_code:org_t)

Ingår i:Journal of Biological Chemistry: American Society for Biochemistry and Molecular Biology281:25, s. 16906-169130021-92581083-351X

Av författaren/redakt...: Gasser, Andreas; Bruhn, Sören, 19 ...; Guse, Andreas

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