Glucose- and phorbol ester-induced insulin secretion in human insulinoma cells--association with protein kinase C activation.
This study examined the effect of glucose and 12-O-tetradecanoylphorbol-13-acetate (TPA) on insulin secretion in isolated human insulinoma cells. In addition, we analyzed conventional PKC alpha and beta activation in the membrane fractions, respectively. Treatment with 5 mM and 20 mM glucose for 5 min and 20 min resulted in 6-7-fold increases in insulin secretion, and treatment with 1 microM TPA for 5 min also resulted in 3-fold increases in insulin secretion from the basal level. Immunoblot analysis of membrane fractions showed increases in PKC alpha and beta immunoreactivities after treatment with 5 mM, 20 mM glucose and 1 microM TPA. Translocations of PKC alpha after treatment with glucose and TPA were greater than those of PKC beta in membrane fractions. These results suggest that TPA independently provokes insulin secretion via PKC activation and that PKC alpha and beta activation may be involved in insulin secretion in human insulinoma cells.
Miura
A
A
Third Department of Internal Medicine, Gifu University School of Medicine, Japan.
Ishizuka
T
T
Itaya
S
S
Ishizawa
M
M
Kanoh
Y
Y
Kimura
M
M
Kajita
K
K
Yasuda
K
K
D000328:Adult; D001692:Biological Transport; D004789:Enzyme Activation; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007328:Insulin; D011493:Protein Kinase C; D005947:Glucose; D013755:Tetradecanoylphorbol Acetate