ADP-ribosyl cyclase couples to cyclic AMP signaling in the cardiomyocytes.
ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca(2+)-mobilizing second messenger cyclic ADP-ribose (cADPR) from beta-NAD(+). In this study, we examined the molecular basis of which beta-adrenergic receptor (betaAR) stimulation induces cADPR formation and characterized cardiac ADPR-cyclase. The results revealed that isoproterenol-mediated increase of [Ca(2+)](i) in rat cardiomyocytes was blocked by pretreatment with a cADPR antagonistic derivative 8-Br-cADPR, a PKA inhibitor H89 or high concentration of ryanodine. Moreover, incubation of ventricular lysates with isoproterenol, forskolin or cAMP resulted in activation of ADPR-cyclase that was inhibited by pretreatment with H89. Supporting the observations, the cADPR antagonist and H89 blocked 8-CPT-cAMP, a cell-permeant cAMP analog-induced increase in [Ca(2+)](i) but not cGMP-mediated increase. Characterization of partially purified cardiac ADPR-cyclase showed a molecular mass of approximately 42 kDa and no cross-activity with CD38 antibodies, and the enzyme activity was inhibited by Zn(2+) but not dithiothreitol. Microinjection of the enzyme into rat cardiomyocytes increased the level of [Ca(2+)](i) in a concentration-dependent manner. The enzyme-mediated increase of [Ca(2+)](i) was blocked by the cADPR antagonist. These findings suggest that betaAR-mediated regulation of [Ca(2+)](i) in rat cardiomyocytes is primed by activation of cardiac ADPR-cyclase via cAMP/PKA signaling and that cardiac ADPR-cyclase differs from CD38 in biochemical and immunological properties.
Xie
Guang-Hua
GH
Department of Biochemistry, Chonbuk National University Medical School, Jeonju 561-182, Republic of Korea.
Rah
So-Young
SY
Kim
Sang-Jin
SJ
Nam
Tae-Sik
TS
Ha
Ki-Chan
KC
Chae
Soo-Wan
SW
Im
Mie-Jae
MJ
Kim
Uh-Hyun
UH
D036541:ADP-ribosyl Cyclase / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D006152:Cyclic GMP / Q000502:physiology; D004229:Dithiothreitol / Q000494:pharmacology*; D004789:Enzyme Activation; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D015398:Signal Transduction; D015032:Zinc / Q000378:metabolism
D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D036541:ADP-ribosyl Cyclase; D006152:Cyclic GMP; D015032:Zinc; D002118:Calcium; D004229:Dithiothreitol