Work

Cutting Edge: Macrophage Inhibition by Cyclic AMP (cAMP): Differential Roles of Protein Kinase A and Exchange Protein Directly Activated by cAMP-1

Year: 2005

Type: article

Abstract: cAMP has largely inhibitory effects on components of macrophage activation, yet downstream mechanisms involved in these effects remain incompletely defined. Elevation of cAMP in alveolar macrophages (AMs) suppresses FcgammaR-mediated phagocytosis. We now report that protein kinase A (PKA) inhibitors (H-89, KT-5720, and myristoylated PKA inhibitory peptide 14-22) failed to prevent this suppression in rat AMs. We identified the expression of the alternative cAMP target, exchange protein directly activated by cAMP-1 (Epac-1), in human and rat AMs. Using cAMP analogs that are highly specific for PKA (N6-benzoyladenosine-3',5'-cAMP) or Epac-1 (8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cAMP), we found that activation of Epac-1, but not PKA, dose-dependently suppressed phagocytosis. By contrast, activation of PKA, but not Epac-1, suppressed AM production of leukotriene B(4) and TNF-alpha, whereas stimulation of either PKA or Epac-1 inhibited AM bactericidal activity and H(2)O(2) production. These experiments now identify Epac-1 in primary macrophages, and define differential roles of Epac-1 vs PKA in the inhibitory effects of cAMP.

Source: The Journal of Immunology

DOI: 10.4049/jimmunol.174.2.595

Authors: David M Aronoff, Claudio Canetti, Carlos H Serezani, Ming Luo, Marc Peters-Golden

Institutions: Michigan Medicine, Universidade de São Paulo

Language: English

Topic: Phosphodiesterase function and regulation

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: National Institutes of Health, National Heart, Lung, and Blood Institute