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Diminished phosphodiesterase-8B potentiates biphasic insulin response to glucose.

Authors: Dov, A  Abramovitch, E  Warwar, N  Nesher, R 
Citation: Dov A, etal., Endocrinology. 2008 Feb;149(2):741-8. Epub 2007 Nov 8.
Pubmed: (View Article at PubMed) PMID:17991719
DOI: Full-text: DOI:10.1210/en.2007-0968

cAMP activates multiple signal pathways, crucial for the pancreatic beta-cells function and survival and is a major potentiator of insulin release. A family of phosphodiesterases (PDEs) terminate the cAMP signals. We examined the expression of PDEs in rat beta-cells and their role in the regulation of insulin response. Using RT-PCR and Western blot analyses, we identified PDE3A, PDE3B, PDE4B, PDE4D, and PDE8B in rat islets and in INS-1E cells and several possible splice variants of these PDEs. Specific depletion of PDE3A with small interfering (si) RNA (siPDE3A) led to a small (67%) increase in the insulin response to glucose in INS-1E cells but not rat islets. siPDE3A had no effect on the glucagon-like peptide-1 (10 nmol/liter) potentiated insulin response in rat islets. Depletion in PDE8B levels in rat islets using similar technology (siPDE8B) increased insulin response to glucose by 70%, the potentiation being of similar magnitude during the first and second phase insulin release. The siPDE8B-potentiated insulin response was further increased by 23% when glucagon-like peptide-1 was included during the glucose stimulus. In conclusion, PDE8B is expressed in a small number of tissues unrelated to glucose or fat metabolism. We propose that PDE8B, an 3-isobutyl-1-methylxanthine-insensitive cAMP-specific phosphodiesterase, could prove a novel target for enhanced insulin response, affecting a specific pool of cAMP involved in the control of insulin granule trafficking and exocytosis. Finally, we discuss evidence for functional compartmentation of cAMP in pancreatic beta-cells.

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CRRD Object Information
CRRD ID: 2312519
Created: 2009-08-20
Species: All species
Last Modified: 2009-08-20
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.