NAD is available in the extracellular environment and elicits immune modulation such as T cell apoptosis by being used as the substrate of cell surface ADP-ribosyl transferase. However, it is unclear whether extracellular NAD affects function of macrophages expressing cell surface ADP-ribosyl transferase. Here we show that extracellular NAD enhances Fcγ receptor (FcγR)-mediated phagocytosis in J774A.1 macrophages via the conversion into cyclic ADP-ribose (cADPR), a potent calcium mobilizer, by CD38, an ADP-ribosyl cyclase. Extracellular NAD increased the phagocytosis of IgG-coated sheep red blood cells (IgG-SRBC) in J774A.1 macrophages, which was completely abolished by pretreatment of 8-bromo-cADPR, an antagonist of cADPR, or CD38 knockdown. Extracellular NAD increased basal intracellular Ca2+ concentration, which also was abolished by pretreatment of 8-bromo-cADPR or CD38 knockdown. Moreover, the chelation of intracellular calcium abolished NAD-induced enhancement of phagocytosis of IgG-SRBC. Our results suggest that extracellular NAD act as a regulator for FcγR-mediated phagocytosis in macrophages.
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - 29 Feb 2008|
Bibliographical noteFunding Information:
This work was supported by grants of the Korea Science and Engineering Foundation (Nos. R01-2002-000-00493-0 and M10528010003-05N2801-00310) and the grant of Post-Doc Program, Chonbuk National University (E.-K. Song).
- Cyclic ADP-ribose
- Fcγ receptor