Identification of cyclic ADP-ribose-dependent mechanisms in pancreatic muscarinic Ca(2+) signaling using CD38 knockout mice.
We showed that muscarinic acetylcholine (ACh)-stimulation increased the cellular content of cADPR in the pancreatic acinar cells from normal mice but not in those from CD38 knockout mice. By monitoring ACh-evoked increases in the cytosolic Ca(2+) concentration ([Ca(2+)](i)) using fura-2 microfluorimetry, we distinguished and characterized the Ca(2+) release mechanisms responsive to cADPR. The Ca(2+) response from the cells of the knockout mice (KO cells) lacked two components of the muscarinic Ca(2+) release present in wild mice. The first component inducible by the low concentration of ACh contributed to regenerative Ca(2+) spikes. This component was abolished by ryanodine treatment in the normal cells and was severely impaired in KO cells, indicating that the low ACh-induced regenerative spike responses were caused by cADPR-dependent Ca(2+) release from a pool regulated by a class of ryanodine receptors. The second component inducible by the high concentration of ACh was involved in the phasic Ca(2+) response, and it was not abolished by ryanodine treatment. Overall, we conclude that muscarinic Ca(2+) signaling in pancreatic acinar cells involves a CD38-dependent pathway responsible for two cADPR-dependent Ca(2+) release mechanisms in which the one sensitive to ryanodine plays a crucial role for the generation of repetitive Ca(2+) spikes.
Fukushi
Y
Y
Department of Physiology I, Tohoku University Graduate School of Medicine, Seiryo-cho 2-1, Aobaku, Sendai 980-8575, Japan.
Kato
I
I
Takasawa
S
S
Sasaki
T
T
Ong
B H
BH
Sato
M
M
Ohsaga
A
A
Sato
K
K
Shirato
K
K
Okamoto
H
H
Maruyama
Y
Y
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000109:Acetylcholine / Q000494:pharmacology*; D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D036563:Cyclic ADP-Ribose; D005470:Fluorometry; D016257:Fura-2; D017353:Gene Deletion; D005838:Genotype; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008562:Membrane Glycoproteins; D051379:Mice; D018345:Mice, Knockout; D009244:NAD+ Nucleosidase / Q000235:genetics / Q000502:physiology*; D010179:Pancreas / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012433:Ryanodine / Q000494:pharmacology
D015703:Antigens, CD; D000943:Antigens, Differentiation; D008562:Membrane Glycoproteins; D011976:Receptors, Muscarinic; D036563:Cyclic ADP-Ribose; D012433:Ryanodine; D000246:Adenosine Diphosphate Ribose; D015544:Inositol 1,4,5-Trisphosphate; D036541:ADP-ribosyl Cyclase; C498155:Cd38 protein, mouse; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2