Protein kinase A phosphorylation of human phosphodiesterase 3B promotes 14-3-3 protein binding and inhibits phosphatase-catalyzed inactivation.
Recent studies confirm that intracellular cAMP concentrations are nonuniform and that localized subcellular cAMP hydrolysis by cyclic nucleotide phosphodiesterases (PDEs) is important in maintaining these cAMP compartments. Human phosphodiesterase 3B (HSPDE3B), a member of the PDE3 family of PDEs, represents the dominant particulate cAMP-PDE activity in many cell types, including adipocytes and cells of hematopoietic lineage. Although several previous reports have shown that phosphorylation of HSPDE3B by either protein kinase A (PKA) or protein kinase B (PKB) activates this enzyme, the mechanisms that allow cells to distinguish these two activated forms of HSPDE3B are unknown. Here we report that PKA phosphorylates HSPDE3B at several distinct sites (Ser-73, Ser-296, and Ser-318), and we show that phosphorylation of HSPDE3B at Ser-318 activates this PDE and stimulates its interaction with 14-3-3 proteins. In contrast, although PKB-catalyzed phosphorylation of HSPDE3B activates this enzyme, it does not promote 14-3-3 protein binding. Interestingly, we report that the PKA-phosphorylated, 14-3-3 protein-bound, form of HSPDE3B is protected from phosphatase-dependent dephosphorylation and inactivation. In contrast, PKA-phosphorylated HSPDE3B that is not bound to 14-3-3 proteins is readily dephosphorylated and inactivated. Our data are presented in the context that a selective interaction between PKA-activated HSPDE3B and 14-3-3 proteins represents a mechanism by which cells can protect this enzyme from deactivation. Moreover, we propose that this mechanism may allow cells to distinguish between PKA- and PKB-activated HSPDE3B.
Palmer
Daniel
D
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Jimmo
Sandra L
SL
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Raymond
Daniel R
DR
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Wilson
Lindsay S
LS
Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Carter
Rhonda L
RL
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Maurice
Donald H
DH
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario K7L 3N6, Canada; Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario K7L 3N6, Canada. Electronic address: mauriced@post.queensu.ca.
D048948:14-3-3 Proteins / Q000378:metabolism*; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology*; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D006801:Humans; D051379:Mice; D041681:NIH 3T3 Cells; D010726:Phosphodiesterase Inhibitors / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000502:physiology; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology
D048948:14-3-3 Proteins; D010726:Phosphodiesterase Inhibitors; D017868:Cyclic AMP-Dependent Protein Kinases; D010744:Phosphoric Monoester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517293:Pde3b protein, mouse