Assessment of cellular mechanisms contributing to cAMP compartmentalization in pulmonary microvascular endothelial cells

TitleAssessment of cellular mechanisms contributing to cAMP compartmentalization in pulmonary microvascular endothelial cells
Publication TypeJournal Article
Year of Publication2012
AuthorsFeinstein WP, Zhu B, Leavesley SJ, Sayner SL, Rich TC
JournalAm J Physiol Cell Physiol
Volume302
Issue6
PaginationC839-52
Date Published2012 Mar
ISSN1522-1563
KeywordsAdenylate Cyclase, Animals, Cell Compartmentation, Cell Culture Techniques, Cell Membrane, Computer Simulation, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Cytosol, Endothelial Cells, Lung, Models, Biological, Phosphoric Diester Hydrolases, Rats, Receptors, G-Protein-Coupled, Signal Transduction
Abstract

Cyclic AMP signals encode information required to differentially regulate a wide variety of cellular responses; yet it is not well understood how information is encrypted within these signals. An emerging concept is that compartmentalization underlies specificity within the cAMP signaling pathway. This concept is based on a series of observations indicating that cAMP levels are distinct in different regions of the cell. One such observation is that cAMP production at the plasma membrane increases pulmonary microvascular endothelial barrier integrity, whereas cAMP production in the cytosol disrupts barrier integrity. To better understand how cAMP signals might be compartmentalized, we have developed mathematical models in which cellular geometry as well as total adenylyl cyclase and phosphodiesterase activities were constrained to approximate values measured in pulmonary microvascular endothelial cells. These simulations suggest that the subcellular localizations of adenylyl cyclase and phosphodiesterase activities are by themselves insufficient to generate physiologically relevant cAMP gradients. Thus, the assembly of adenylyl cyclase, phosphodiesterase, and protein kinase A onto protein scaffolds is by itself unlikely to ensure signal specificity. Rather, our simulations suggest that reductions in the effective cAMP diffusion coefficient may facilitate the formation of substantial cAMP gradients. We conclude that reductions in the effective rate of cAMP diffusion due to buffers, structural impediments, and local changes in viscosity greatly facilitate the ability of signaling complexes to impart specificity within the cAMP signaling pathway.

DOI10.1152/ajpcell.00361.2011
Alternate JournalAmerican journal of physiology. Cell physiology

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