Synthesis and hydrolysis of cyclic ADP-ribose by human leukocyte antigen CD38 and inhibition of the hydrolysis by ATP.
Cyclic ADP-ribose (cADPR) has been recently shown to be generated in pancreatic beta-cells by glucose stimulation, serving as a second messenger for Ca2+ mobilization in the endoplasmic reticulum in the process of insulin secretion (Takasawa, S., Nata, K., Yonekura, H., and Okamoto, H. (1993) Science 259, 370-373). In the present study, we isolated a cDNA for CD38, which has been reported to be a human leukocyte antigen, from a human insulinoma and expressed the cDNA in COS-7 cells. CD38 expression was observed in the plasma membrane and the microsome fractions of the COS-7 cells. When we incubated the plasma membrane fraction with NAD+ and analyzed the reaction products by high pressure liquid chromatography, the formation of cADPR was observed in addition to the ADP-ribose (ADPR) formation. When the plasma membrane fraction was incubated with cADPR, cADPR was converted to ADPR stoichiometrically. These results suggest that CD38 has both cADPR-forming and -hydrolyzing activities. Moreover, we found that ATP (2-10 mM), generated in the glucose metabolism in beta-cells, inhibited the cADPR-hydrolyzing activity, resulting in the increased formation of cADPR. These findings indicate a role for CD38 in the synthesis and hydrolysis of cADPR in the process of insulin secretion in pancreatic beta-cells.
Takasawa
S
S
Department of Biochemistry, Tohoku University School of Medicine, Miyagi, Japan.
Tohgo
A
A
Noguchi
N
N
Koguma
T
T
Nata
K
K
Sugimoto
T
T
Yonekura
H
H
Okamoto
H
H
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism*; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002478:Cells, Cultured; D036563:Cyclic ADP-Ribose; D017931:DNA Primers; D006801:Humans; D006868:Hydrolysis; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D015703:Antigens, CD; D000943:Antigens, Differentiation; D017931:DNA Primers; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D000255:Adenosine Triphosphate; D009699:N-Glycosyl Hydrolases; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1