title: Compartmentalization of PDE-4 and cAMP-dependent protein kinase in neutrophils and macrophages during phagocytosis.
abstract: The compartmentalization of cAMP in human neutrophils during phagocytosis of serum-opsonized zymosan suggests that cAMP is an important second messenger for regulating phagocytosis. Type 4 cAMP-specific phosphodiesterase (PDE-4), cAMP-dependent protein kinase (PKA), and adenylate cyclase are the principal effector molecules for cAMP regulation in phagocytes. Immunofluorescence microscopy demonstrated that PDE-4 isoforms (HSPDE-4A, HSPDE-4B, HSPDE-4D) were targeted to the forming phagosome in neutrophils, and were colocalized with the catalytic subunit of PKA and degranulated myeloperoxidase. Phagocytosis and accumulation of PDE-4 and PKA near adherent zymosan were inhibited by elevating cAMP levels with forskolin or rolipram. cAMP, PDE-4, and PKA were localized at sites of zymosan adherence in cells treated with cytochalasin D to inhibit phagosome formation, suggesting that zymosan engagement to Fc/CR3 receptors triggers cAMP elevations at sites of phagocytosis. HSPDE-4A, HSPDE-4B, HSPDE-4D, and PKA also were localized at the forming phagosome in monocyte-derived macrophages, and the lysosomal marker CD63 demonstrated the absence of PDE-4 around internalized phagolysosomes. These results suggest that cAMP levels are focally regulated by PDE-4 at the nascent phagosome, and that PKA may phosphorylate proteins associated with pseudopodia formation and phagosome internalization.
authors.affiliation: Department of Pathology, University of North Carolina, Chapel Hill 27599-7525, USA. KBP@med.unc.edu
authors.forename: K B
authors.initials: KB
authors.lastname: Pryzwansky
authors.forename: S
authors.initials: S
authors.lastname: Kidao
authors.forename: E P
authors.initials: EP
authors.lastname: Merricks
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000032:analysis*; D002448:Cell Adhesion; D002451:Cell Compartmentation / Q000276:immunology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000032:analysis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000032:analysis*; D006152:Cyclic GMP / Q000032:analysis; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D015638:Cytochalasin D / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000032:analysis; D008264:Macrophages / Q000201:enzymology* / Q000276:immunology; D009504:Neutrophils / Q000201:enzymology* / Q000276:immunology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009195:Peroxidase / Q000032:analysis; D010587:Phagocytosis; D010588:Phagosomes / Q000201:enzymology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D020889:Rolipram; D015398:Signal Transduction / Q000276:immunology; D015054:Zymosan
chemical_list: D007527:Isoenzymes; D019384:Nucleic Acid Synthesis Inhibitors; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D005576:Colforsin; D015638:Cytochalasin D; D015054:Zymosan; D000242:Cyclic AMP; D009195:Peroxidase; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D006152:Cyclic GMP; D020889:Rolipram