- Erratum in:
- J Cell Biol 1999 Sep 20;146(6):following 1399.
CD38/ADP-ribosyl cyclase: A new role in the regulation of osteoclastic bone resorption.
Sun L,
Adebanjo OA,
Moonga BS,
Corisdeo S,
Anandatheerthavarada HK,
Biswas G,
Arakawa T,
Hakeda Y,
Koval A,
Sodam B,
Bevis PJ,
Moser AJ,
Lai FA,
Epstein S,
Troen BR,
Kumegawa M,
Zaidi M.
Center for Osteoporosis and Skeletal Aging, Department of Medicine, Medical College of Pennsylvania and Veterans Affairs Medical Center, Philadelphia, Pennsylvania 19104, USA.
The multifunctional ADP-ribosyl cyclase, CD38, catalyzes the cyclization of NAD(+) to cyclic ADP-ribose (cADPr). The latter gates Ca(2+) release through microsomal membrane-resident ryanodine receptors (RyRs). We first cloned and sequenced full-length CD38 cDNA from a rabbit osteoclast cDNA library. The predicted amino acid sequence displayed 59, 59, and 50% similarity, respectively, to the mouse, rat, and human CD38. In situ RT-PCR revealed intense cytoplasmic staining of osteoclasts, confirming CD38 mRNA expression. Both confocal microscopy and Western blotting confirmed the plasma membrane localization of the CD38 protein. The ADP-ribosyl cyclase activity of osteoclastic CD38 was next demonstrated by its ability to cyclize the NAD(+) surrogate, NGD(+), to its fluorescent derivative cGDP-ribose. We then examined the effects of CD38 on osteoclast function. CD38 activation by an agonist antibody (A10) in the presence of substrate (NAD(+)) triggered a cytosolic Ca(2+) signal. Both ryanodine receptor modulators, ryanodine, and caffeine, markedly attenuated this cytosolic Ca(2+) change. Furthermore, the anti-CD38 agonist antibody expectedly inhibited bone resorption in the pit assay and elevated interleukin-6 (IL-6) secretion. IL-6, in turn, enhanced CD38 mRNA expression. Taken together, the results provide compelling evidence for a new role for CD38/ADP-ribosyl cyclase in the control of bone resorption, most likely exerted via cADPr.
PMID: 10477767 [PubMed - indexed for MEDLINE]
PMCID: PMC2169484