title: Transient increase in cyclic AMP localized to macrophage phagosomes.
abstract: Cyclic AMP (cAMP) regulates many biological processes and cellular functions. The importance of spatially localized intracellular gradients of cAMP is increasingly appreciated. Previous work in macrophages has shown that cAMP is produced during phagocytosis and that elevated cAMP levels suppress host defense functions, including generation of proinflammatory mediators, phagocytosis and killing. However, the spatial and kinetic characteristics of cAMP generation in phagocytosing macrophages have yet to be examined. Using a Förster resonance energy transfer (FRET)-based cAMP biosensor, we measured the generation of cAMP in live macrophages. We detected no difference in bulk intracellular cAMP levels between resting cells and cells actively phagocytosing IgG-opsonized particles. However, analysis with the biosensor revealed a rapid decrease in FRET signal corresponding to a transient burst of cAMP production localized to the forming phagosome. cAMP levels returned to baseline after the particle was internalized. These studies indicate that localized increases in cAMP accompany phagosome formation and provide a framework for a more complete understanding of how cAMP regulates macrophage host defense functions.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Health Systems, Ann Arbor, Michigan, United States of America.
authors.forename: Megan N
authors.initials: MN
authors.lastname: Ballinger
authors.forename: Timothy
authors.initials: T
authors.lastname: Welliver
authors.forename: Samuel
authors.initials: S
authors.lastname: Straight
authors.forename: Marc
authors.initials: M
authors.lastname: Peters-Golden
authors.forename: Joel A
authors.initials: JA
authors.lastname: Swanson
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D010587:Phagocytosis; D010588:Phagosomes / Q000378:metabolism*
chemical_list: D000242:Cyclic AMP