Important role of phosphodiesterase 3B for the stimulatory action of cAMP on pancreatic beta-cell exocytosis and release of insulin.
Cyclic AMP potentiates glucose-stimulated insulin release and mediates the stimulatory effects of hormones such as glucagon-like peptide 1 (GLP-1) on pancreatic beta-cells. By inhibition of cAMP-degrading phosphodiesterase (PDE) and, in particular, selective inhibition of PDE3 activity, stimulatory effects on insulin secretion have been observed. Molecular and functional information on beta-cell PDE3 is, however, scarce. To provide such information, we have studied the specific effects of the PDE3B isoform by adenovirus-mediated overexpression. In rat islets and rat insulinoma cells, approximate 10-fold overexpression of PDE3B was accompanied by a 6-8-fold increase in membrane-associated PDE3B activity. The cAMP concentration was significantly lowered in transduced cells (INS-1(832/13)), and insulin secretion in response to stimulation with high glucose (11.1 mm) was reduced by 40% (islets) and 50% (INS-1). Further, the ability of GLP-1 (100 nm) to augment glucose-stimulated insulin secretion was inhibited by approximately 30% (islets) and 70% (INS-1). Accordingly, when stimulating with cAMP, a substantial decrease (65%) in exocytotic capacity was demonstrated in patch-clamped single beta-cells. In untransduced insulinoma cells, application of the PDE3-selective inhibitor OPC3911 (10 microm) was shown to increase glucose-stimulated insulin release as well as cAMP-enhanced exocytosis. The findings suggest a significant role of PDE3B as an important regulator of insulin secretory processes.
Härndahl
Linda
L
Department of Cell and Molecular Biology, Biomedical Centre, C11, Lund University, SE-221 84 Lund, Sweden. Linda.Harndahl@medkem.lu.se
Jing
Xing-Jun
XJ
Ivarsson
Rosita
R
Degerman
Eva
E
Ahrén
Bo
B
Manganiello
Vincent C
VC
Renström
Erik
E
Holst
Lena Stenson
LS
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology*; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D017931:DNA Primers; D005089:Exocytosis / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma; D007515:Islets of Langerhans / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D008297:Male; D010190:Pancreatic Neoplasms; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D007328:Insulin; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517294:Pde3b protein, rat; D005947:Glucose