| 1. |
- 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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| 2. |
- Ahmad, Faiyaz, et al.
(författare)
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Differential regulation of adipocyte PDE3B in distinct membrane compartments by insulin and the beta(3)-adrenergic receptor agonist CL316243: effects of caveolin-1 knockdown on formation/maintenance of macromolecular signalling complexes
- 2009
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Ingår i: BIOCHEMICAL JOURNAL. - 0264-6021. ; 424:3, s. 399-410
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Tidskriftsartikel (refereegranskat)abstract
- In adipocytes, PDE3B (phosphodiesterase 3B) is an important regulatory effector in signalling pathways controlled by insulin and cAMP-increasing hormones. Stimulation of 3T3-L1 adipocytes with insulin or the beta(3)-adrenergic receptor agonist CL316243 (termed CL) indicated that insulin preferentially phosphorylated/activated PDE3B associated with internal membranes (endoplasmic reticulum/Golgi), whereas CL preferentially phosphorylated/activated PDE3B associated with caveolae. siRNA (small interfering RNA)-mediated KD (knockdown) of CAV-1 (caveolin-1) in 3T3-L1 adipocytes resulted in down-regulation of expression of membrane-associated PDE3B. Insulin-induced activation of PDE3B was reduced, whereas CL-mediated activation was almost totally abolished. Similar results were obtained in adipocytes from Cav-1-deficient mice. siRNA-mediated KID of CAV-1 in 3T3-L1 adipocytes also resulted in inhibition of CL-stimulated phosphorylation of HSL (hormone-sensitive lipase) and perilipin A, and of lipolysis. Superose 6 gel-filtration chromatography of solubilized membrane proteins from adipocytes stimulated with insulin or CL demonstrated the reversible assembly of distinct macromolecular complexes that contained P-32-phosphorylated PDE3B and signalling molecules thought to be involved in its activation. Insulin- and CL-induced macromolecular complexes were enriched in cholesterol, and contained certain common signalling proteins [14-3-3, PP2A (protein phosphatase 2A) and cav-1]. The complexes present in insulin-stimulated cells contained tyrosine-phosphorylated IRS-1 (insulin receptor substrate 1) and its downstream signalling proteins, whereas CL-activated complexes contained beta(3)-adrenergic receptor, PKA-RII [PKA (cAMP-dependent protein kinase)-regulatory subunit] and HSL. Insulin- and CL-mediated macromolecular complex formation was significantly inhibited by CAV-1 KID. These results suggest that cav-1 acts as a molecular chaperone or scaffolding molecule in cholesterol-rich lipid rafts that may be necessary for the proper stabilization and activation of PDE3B in response to CL and insulin.
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| 3. |
- Ahmad, Faiyaz, et al.
(författare)
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Insulin-induced formation of macromolecular complexes involved in activation of cyclic nucleotide phosphodiesterase 3B (PDE3B) and its interaction with PKB
- 2007
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Ingår i: Biochemical Journal. - 0264-6021. ; 404, s. 257-268
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Tidskriftsartikel (refereegranskat)abstract
- Fractionation of 3T3-L1 adipocyte membranes revealed that PDE3B (phosphodiesterase 3B) was associated with PM (plasma membrane) and ER (endoplasmic reticulum)/Golgi fractions, that insulin-induced phosphorylation/activation of PDE3B was greater in internal membranes than PM fractions, and that there was no significant translocation of PDE3B between membrane fractions. Insulin also induced formation of large macromolecular complexes, separated during gel filtration (Superose 6 columns) of solubilized membranes, which apparently contain phosphorylated/activated PDE3B and signalling molecules potentially involved in its activation by insulin, e.g. IRS-1 (insulin receptor substrate-1), IRS-2, PI3K p85 [p85-subunit of PI3K (phospho-inosifide 3-kinase)], PKB (protein kinase B), HSP-90 (heat-shock protein 90) and 14-3-3. Expression of full-length recombinant FLAG-tagged murine (M) PDE3B and M3B Delta 604 (MPDE3B lacking N-terminal 604 amino acids) indicated that the N-terminal region of MPDE3B was necessary for insulin-induced activation and recruitment of PDE3B. siRNA (small interfering RNA) knock-down of PDE3B indicated that PDE3B was not required for formation of insulin-induced complexes. Wortmannin inhibited insulin-induced assembly of macromolecular complexes, as well as phosphorylation/activation of PKB and PDE3B, and their coimmunoprecipitation. Another PI3K inhibitor, LY294002, and the tyrosine kinase inhibitor, Genistein, also inhibited insulin-induced activation of PDE3B and its co-immunoprecipitation with PKB. Confocal microscopy indicated co-localization of PDE3B and PKB. Recombinant MPDE3B co-immunoprecipitated, and co-eluted during Superose 12 chromatography, to a greater extent with recombinant pPKB (phosphorylated/activated PKB) than dephospho-PKB or p-Delta PKB [pPKB lacking its PH domain (pleckstrin homology domain)]. Truncated recombinant MPDE3B proteins and pPKB did not efficiently co-immunoprecipitate, suggesting that structural determinants for their interaction reside in, or are regulated by, the N-terminal portion of MPDE3B. Recruitment of PDE3B in macromolecular complexes may be critical for regulation of specific cAMP pools and signalling pathways by insulin, e.g. lipolysis.
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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. |
- Lindh, Rebecka, et al.
(författare)
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Multisite phosphorylation of adipocyte and hepatocyte phosphodiesterase 3B.
- 2007
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Ingår i: Biochimica et Biophysica Acta: Molecular Cell Research. - : Elsevier BV. - 0167-4889. ; 1773:4, s. 584-592
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Tidskriftsartikel (refereegranskat)abstract
- Phosphodiesterase 3B (PDE3B) is an important component of insulin and cAMP-dependent signalling pathways. In order to study phosphorylation of PDE3B, we have used an adenoviral system to express recombinant flag-tagged PDE3B in primary rat adipocytes and H4IIE hepatoma cells. Phosphorylation of PDE3B after treatment of cells with insulin, cAMP-increasing agents, or the phosphatase inhibitor, calyculin A was analyzed by two-dimensional tryptic phosphopeptide mapping and mass spectrometry. We found that PDE3B is multisite phosphorylated in adipocytes and H4IIE hepatoma cells in response to all these stimuli. Several sites were identified; serine (S)273, S296, S421, S424/5, S474 and S536 were phosphorylated in adipocyte as well as H4IIE hepatoma cells whereas S277 and S507 were phosphorylated in hepatoma cells only. Several of the sites were phosphorylated by insulin as well as cAMP-increasing hormones indicating integration of the two signalling pathways upstream of PDE3B, maybe at the level of protein kinase B.
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| 6. |
- Nilsson, Rebecka, et al.
(författare)
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Plasma membrane cyclic nucleotide phosphodiesterase 3B (PDE3B) is associated with caveolae in primary adipocytes.
- 2006
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Ingår i: Cellular Signalling. - : Elsevier BV. - 1873-3913 .- 0898-6568. ; 18:2006 Feb 24, s. 1713-1721
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Tidskriftsartikel (refereegranskat)abstract
- Caveolae, plasma membrane invaginations particularly abundant in adipocytes, have been suggested to be important in organizing insulin signalling. Insulin-induced activation of the membrane bound cAMP degrading enzyme, phosphodiesterase 3B (PDE3B) is a key step in insulin-mediated inhibition of lipolysis and is also involved in the regulation of insulin-mediated glucose uptake and lipogenesis in adipocytes. The aim of this work was to evaluate whether PDE3B is associated with caveolae. Subcellular fractionation of primary rat and mouse adipocytes demonstrated the presence of PDE3B in endoplasmic reticulum and plasma membrane fractions. The plasma membrane PDE3B was further analyzed by detergent treatment at 4 degrees C, which did not solubilize PDE3B, indicating an association of PDE3B with lipid rafts. Detergent-treated plasma membranes were studied using Superose-6 chromatography which demonstrated co-elution of PDE3B with caveolae and lipid raft markers (caveolin-1, flotillin-1 and cholesterol) at a Mw of > 4000 kDa. On sucrose density gradient centrifugation of sonicated plasma membranes, a method known to enrich caveolae, PDE3B co-migrated with the caveolae markers. Immunoprecipitation of caveolin-1 using anti caveolin-1 antibodies co-immunoprecipitated PDE3B and immunoprecipitation of flag-PDE3B from adipocytes infected with a flag-PDE3B adenovirus resulted in co-immunoprecipitation of caveolin-1. Studies on adipocytes with disrupted caveolae, using either caveolin-1 deficient mice or treatment of adipocytes with methyl-beta-cyclodextrin, reduced the membrane associated PDE3B activity. Furthermore, inhibition of PDE3 in primary rat adipocytes resulted in reduced insulin stimulated glucose transporter-4 translocation to caveolae, isolated by immunoprecipitation using caveolin-1 antibodies. Thus, PDE3B, a key enzyme in insulin signalling, appears to be associated with caveolae in adipocytes and this localization seems to be functionally important. (c) 2006 Elsevier Inc. All rights reserved.
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