ATP enhances exocytosis of insulin secretory granules in pancreatic islets under Ca2+-depleted condition

Glucose and other nutrients have been shown to stimulate insulin release from pancreatic islets under Ca2+-depleted condition when protein kinase A (PKA) and protein kinase C (PKC) are activated simultaneously. We investigated the role of metabolic nucleotide signals including ATP, ADP, and GTP in e...

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Bibliographic Details
Published in:Diabetes research and clinical practice 2005-09, Vol.69 (3), p.216-223
Main Authors: Shimono, Dai, Fujimoto, Shimpei, Mukai, Eri, Takehiro, Mihoko, Nabe, Koichiro, Radu, Razvan Gheorghe, Shimodahira, Makiko, Kominato, Rieko, Aramaki, Yo, Nishi, Yuichi, Funakoshi, Shogo, Yamada, Yuichiro, Seino, Yutaka
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - analogs & derivatives
Adenosine Triphosphate - pharmacology
Adenylyl Imidodiphosphate - pharmacology
Animals
Calcium - physiology
Exocytosis - drug effects
Exocytosis - physiology
Insulin - metabolism
Insulin Secretion
Islets of Langerhans - drug effects
Islets of Langerhans - metabolism
Kinetics
Male
Rats
Rats, Wistar
Tetradecanoylphorbol Acetate - pharmacology
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Summary:Glucose and other nutrients have been shown to stimulate insulin release from pancreatic islets under Ca2+-depleted condition when protein kinase A (PKA) and protein kinase C (PKC) are activated simultaneously. We investigated the role of metabolic nucleotide signals including ATP, ADP, and GTP in exocytosis of insulin secretory granules under Ca2+-depleted condition using electrically permeabilized rat islets. ATP under PKC activation augmented insulin release concentration-dependently by 100 nM 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in Ca2+-depleted condition, while ADP could not suppress ATP-dependent insulin release in this condition. Neither GTP nor activated PKA in the absence of PKC activation increased insulin release under Ca2+-depleted condition in the presence of ATP, but both enhanced insulin secretion in the presence of ATP when PKC was activated. In conclusion, activated PKC and the presence of ATP both are required in the insulin secretory process under Ca2+-depleted condition. While PKA activation and GTP cannot substitute for PKC activation and ATP, respectively, under Ca2+-depleted condition, they enhance ATP-dependent insulin secretion when PKC is activated.
ISSN:0168-8227
DOI:10.1016/j.diabres.2005.01.010