title: 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.
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.
authors.affiliation: Pulmonary/Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA. ahmadf@nhlbi.nih.gov
authors.forename: F
authors.initials: F
authors.lastname: Ahmad
authors.forename: L N
authors.initials: LN
authors.lastname: Cong
authors.forename: L
authors.initials: L
authors.lastname: Stenson Holst
authors.forename: L M
authors.initials: LM
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Rahn Landstrom
authors.forename: J H
authors.initials: JH
authors.lastname: Pierce
authors.forename: M J
authors.initials: MJ
authors.lastname: Quon
authors.forename: E
authors.initials: E
authors.lastname: Degerman
authors.forename: V C
authors.initials: VC
authors.lastname: Manganiello
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000502:physiology; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005822:Genetic Vectors; D006412:Hematopoietic Stem Cells / Q000201:enzymology* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism*; D014162:Transfection; D051025:bcl-Associated Death Protein
chemical_list: C494820:Bad protein, mouse; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051025:bcl-Associated Death Protein; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517293:Pde3b protein, mouse; D013936:Thymidine