CD38: A NAADP degrading enzyme

The role of the multifunctional enzyme CD38 in formation of the Ca2+-mobilizing second messenger nicotinic acid adenine dinucleotide phosphate (NAADP) was investigated. Gene silencing of CD38 did neither inhibit NAADP synthesis in intact Jurkat T cells nor in thymus or spleen obtained from CD38 knock out mice. In vitro, both NAADP formation by base-exchange and degradation to 2-phospho adenosine diphosphoribose were efficiently decreased. Thus in vivo CD38 appears to be a NAADP degrading rather than a NAADP forming enzyme, perhaps avoiding desensitizing NAADP levels in intact cells.

► We studied the role of CD38 in formation of the second messenger NAADP.
► We used gene silencing and CD38 KO mice to show a lack of inhibition of NAADP synthesis.
► We conclude that CD38 appears to be a NAADP degrading enzyme in intact cells.