| 1. |
- Jones, Helena, et al.
(författare)
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beta-cell PDE3B regulates Ca(2+)-stimulated exocytosis of insulin.
- 2007
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Ingår i: Cellular Signalling. - : Elsevier BV. - 1873-3913 .- 0898-6568. ; 19:Feb 12, s. 1505-1513
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Tidskriftsartikel (refereegranskat)abstract
- cAMP signaling is important for the regulation of insulin secretion in pancreatic beta-cells. The level of intracellular cAMP is controlled through its production by adenylyl cyclases and its breakdown by cyclic nucleotide phosphodiesterases (PDEs). We have previously shown that PDE3B is involved in the regulation of nutrient-stimulated insulin secretion. Here, aiming at getting deeper functional insights, we have examined the role of PDE3B in the two phases of insulin secretion as well as its localization in the beta-cell. Depolarization-induced insulin secretion was assessed and in models where PDE3B was overexpressed [islets from transgenic RIP-PDE3B/7 mice and adenovirally (AdPDE3B) infected INS-I (832/13) cells], the first phase of insulin secretion, occurring in response to stimulation with high K+ for 5 min, was significantly reduced (similar to 25% compared to controls). In contrast, in islets from PDE3B(-/-) mice the response to high K+ was increased. Further, stimulation of isolated beta-cells from RIP-PDE3B/7 islets, using successive trains of voltage-clamped depolarizations, resulted in reduced Ca2+-triggered first phase exocytotic response as well as reduced granule mobilization-dependent second phase, compared to wild-type beta-cells. Using sub-cellular fractionation, confocal microscopy and transmission electron microscopy of isolated mouse islets and INS-1 (832/13) cells, we show that endogenous and overexpressed PDE3B is localized to insulin granules and plasma membrane. We conclude that PDE3B, through hydrolysis of cAMP in pools regulated by Ca2+, plays a regulatory role in depolarization-induced insulin secretion and that the enzyme is associated with the exocytotic machinery in beta-cells. (c) 2007 Elsevier Inc. All rights reserved.
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| 2. |
- Ahmad, Faiyaz, et al.
(författare)
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Adenovirus-mediated overexpression of murine cyclic nucleotide phosphodiesterase 3B
- 2005
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Ingår i: Methods in molecular biology (Clifton, N.J.). - New Jersey : Humana Press. - 1940-6029 .- 1064-3745. ; 307, s. 93-107
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- To construct the recombinant adenovirus vector containing the cDNA for recombinant mouse cyclic nucleotide phosphodiesterase 3B (mPDE3B), the cDNA for mPDE3B was subcloned into pACCMV.pLpA. Subsequently, this recombinant plasmid, pACCMV.mPDE3B, was cotransfected with pJM17 plasmid containing the adenoviral genome into 293 human embryonic kidney cells, and the replication-deficient adenovirus AdCMV.mPDE3B was generated via homologous recombination. Large-scale preparation of adenovirus yielded 10(11)-10(13) viral particles/mL and could be quantitated by real-time polymerase chain reaction using iCycler (Bio-Rad). Efficiency of gene transfer was assessed by infecting FDCP2 or H4IIE cells with a recombinant adenovirus expressing beta-galactosidase (beta-gal); greater than 75% of cells were infected. Expression of mPDE3B in H4IIE hepatoma cells, FDCP2 hematopoietic cells, and beta-cells from isolated pancreatic islets was detected by Western blot analysis. In lysates from FDCP2 cells and H4IIE hepatoma cells infected with recombinant adenoviral mPDE3B constructs, mPDE3B activity was increased 10- to 30-fold compared with the activity in lysates from cells infected with beta-gal adenovirus. Stimulation of FDCP2 cells infected with mPDE3B adenovirus with insulin (100 nM, 10 min) resulted in an approx 1.7-fold increase in endogenous PDE3B and recombinant wild-type PDE3B activities. Infection of rat pancreatic islets resulted in a 5- to 10-fold increase in PDE3B expression and activity and subsequent blunting of insulin secretion. Thus, adenovirus-mediated gene transfer is effective for studying expression and regulation of recombinant PDE3 in insulin-responsive cells as well as insulin-secreting cells.
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| 3. |
- Ahmad, F, et al.
(författare)
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Cyclic nucleotide phosphodiesterase 3B is a downstream target of protein kinase B and may be involved in regulation of effects of protein kinase B on thymidine incorporation in FDCP2 cells
- 2000
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Ingår i: Journal of Immunology. - 1550-6606. ; 164:9, s. 4678-4688
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Tidskriftsartikel (refereegranskat)abstract
- Wild-type (F/B), constitutively active (F/B*), and three kinase-inactive (F/Ba-, F/Bb-, F/Bc-) forms of Akt/protein kinase B (PKB) were permanently overexpressed in FDCP2 cells. In the absence of insulin-like growth factor-1 (IGF-1), activities of PKB, cyclic nucleotide phosphodiesterase 3B (PDE3B), and PDE4 were similar in nontransfected FDCP2 cells, mock-transfected (F/V) cells, and F/B and F/B- cells. In F/V cells, IGF-1 increased PKB, PDE3B, and PDE4 activities approximately 2-fold. In F/B cells, IGF-1, in a wortmannin-sensitive manner, increased PKB activity approximately 10-fold and PDE3B phosphorylation and activity ( approximately 4-fold), but increased PDE4 to the same extent as in F/V cells. In F/B* cells, in the absence of IGF-1, PKB activity was markedly increased ( approximately 10-fold) and PDE3B was phosphorylated and activated (3- to 4-fold); wortmannin inhibited these effects. In F/B* cells, IGF-1 had little further effect on PKB and activation/phosphorylation of PDE3B. In F/B- cells, IGF-1 activated PDE4, not PDE3B, suggesting that kinase-inactive PKB behaved as a dominant negative with respect to PDE3B activation. Thymidine incorporation was greater in F/B* cells than in F/V cells and was inhibited to a greater extent by PDE3 inhibitors than by rolipram, a PDE4 inhibitor. In F/B cells, IGF-1-induced phosphorylation of the apoptotic protein BAD was inhibited by the PDE3 inhibitor cilostamide. Activated PKB phosphorylated and activated rPDE3B in vitro. These results suggest that PDE3B, not PDE4, is a target of PKB and that activated PDE3B may regulate cAMP pools that modulate effects of PKB on thymidine incorporation and BAD phosphorylation in FDCP2 cells.
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| 4. |
- Choi, Young Hun, et al.
(författare)
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Alterations in regulation of energy homeostasis in cyclic nucleotide phosphodiesterase 3B-null mice
- 2006
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 116:12, s. 3240-3251
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Tidskriftsartikel (refereegranskat)abstract
- Cyclic nucleotide phosphodiesterase 3B (PDE3B) has been suggested to be critical for mediating insulin/IGF-1 inhibition of cAMP signaling in adipocytes, liver, and pancreatic beta cells. In Pde3b-KO adipocytes we found decreased adipocyte size, unchanged insulin-stimulated phosphorylation of protein kinase B and activation of glucose uptake, enhanced catecholamine-stimulated lipolysis and insulin-stimulated hpogenesis, and blocked insulin inhibition of catecholamine-stimulated lipolysis. Glucose, alone or in combination with glucagon-like peptide-1, increased insulin secretion more in isolated pancreatic KO islets, although islet size and morphology and immunoreactive insulin and glucagon levels were unchanged. The beta(3)-adrenergic agonist CL 316,243 (CL) increased lipolysis and serum insulin more in KO mice, but blood glucose reduction was less in CL-treated KO mice. Insulin resistance was observed in KO mice, with liver an important site of alterations in insulin-sensitive glucose production. In KO mice, liver triglyceride and cAMP contents were increased, and the liver content and phosphorylation states of several insulin signaling, gluconeogenic, and inflammation- and stress-related components were altered. Thus, PDE3B may be important in regulating certain cAMP signaling pathways, including lipolysis, insulin-induced antilipolysis, and cAMP-mediated insulin secretion. Altered expression and/or regulation of PDE3B may contribute to metabolic dysregulation, including systemic insulin resistance.
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| 5. |
- Degerman, Eva, et al.
(författare)
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From PDE3B to the regulation of energy homeostasis.
- 2011
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Ingår i: Current Opinion in Pharmacology. - : Elsevier BV. - 1471-4973 .- 1471-4892. ; 11, s. 676-682
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Tidskriftsartikel (refereegranskat)abstract
- The incidence of obesity in the developed world is increasing at an alarming rate. Concurrent with the increase in the incidence of obesity is an increase in the incidence of type 2 diabetes. Cyclic AMP (cAMP) and cGMP are key second messengers in all cells; for example, when it comes to processes of relevance for the regulation of energy metabolism, cAMP is a key mediator in the regulation of lipolysis, glycogenolysis, gluconeogenesis and pancreatic β cell insulin secretion. PDE3B, one of several enzymes which hydrolyze cAMP and cGMP, is expressed in cells of importance for the regulation of energy homeostasis, including adipocytes, hepatocytes, hypothalamic cells and β cells. It has been shown, using PDE3 inhibitors and gene targeting approaches in cells and animals, that altered levels of PDE3B result in a number of changes in the regulation of glucose and lipid metabolism and in overall energy homeostasis. This article highlights the complexity involved in the regulation of PDE3B by hormones, and in the regulation of downstream metabolic effects by PDE3B in several interacting tissues.
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| 6. |
- Degerman, Eva, et al.
(författare)
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Phosphorylation and activation of hormone-sensitive adipocyte phosphodiesterase type 3B
- 1998
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Ingår i: Methods. - : Elsevier BV. - 1095-9130 .- 1046-2023. ; 14:1, s. 43-53
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Tidskriftsartikel (refereegranskat)abstract
- Phosphodiesterases (PDEs) include a large group of structurally related enzymes that belong to at least seven related gene families (PDEs 1-7) that differ in their primary structure, affinity for cAMP and cGMP, response to specific effectors, sensitivity to specific inhibitors, and regulatory mechanism. One characteristic of PDE3s involves their phosphorylation and activation in response to insulin as well as to agents that increase cAMP in adipocytes, hepatocytes, and platelets and in response to insulin-like growth factor 1 in pancreatic beta cells. In adipocytes, activation of the membrane-associated PDE3B is the major mechanism whereby insulin antagonizes catecholamine-induced lipolysis. PDE3B activation results in increased degradation of cAMP and, thereby, a lowering of the activity of cAMP-dependent protein kinase (PKA). The reduced activity of PKA leads to a net dephosphorylation and decreased activity of hormone-sensitive lipase and reduced hydrolysis of triglycerides. Activation of the rat adipocyte PDE3B by insulin is associated with phosphorylation of serine-302. The mechanism whereby insulin stimulation leads to phosphorylation/activation of PDE3B is only partly understood. In rat adipocytes, lipolytic hormones and other agents that increase cAMP, including isoproterenol, also induce rapid phosphorylation, presumably catalyzed by PKA, of serine-302 of PDE3B. The phosphorylation is associated with activation of the enzyme, most likely representing "feedback" regulation of cAMP, presumably allowing close coupling of the regulation of steady-state concentrations of both cAMP and PKA and, thereby, control of lipolysis. In the review we describe methods and strategies used in the authors' laboratories to study phosphorylation and activation of PDE3B in adipocytes and in vitro.
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| 7. |
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| 8. |
- Heimann, Emilia, et al.
(författare)
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Expression and regulation of cyclic nucleotide phosphodiesterases in human and rat pancreatic islets.
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- As shown by transgenic mouse models and by using phosphodiesterase 3 (PDE3) inhibitors, PDE3B has an important role in the regulation of insulin secretion in pancreatic β-cells. However, very little is known about the regulation of the enzyme. Here, we show that PDE3B is activated in response to high glucose, insulin and cAMP elevation in rat pancreatic islets and INS-1 (832/13) cells. Activation by glucose was not affected by the presence of diazoxide. PDE3B activation was coupled to an increase as well as a decrease in total phosphorylation of the enzyme. In addition to PDE3B, several other PDEs were detected in human pancreatic islets: PDE1, PDE3, PDE4C, PDE7A, PDE8A and PDE10A. We conclude that PDE3B is activated in response to agents relevant for β-cell function and that activation is linked to increased as well as decreased phosphorylation of the enzyme. Moreover, we conclude that several PDEs are present in human pancreatic islets.
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| 9. |
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| 10. |
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