title: Direct measurement of cyclic AMP diffusion and signaling through connexin43 gap junctional channels.
abstract: Gap junctions (GJ) are clusters of transmembrane channels that allow direct cell-to-cell transfer of ions and small molecules. The GJ-permeant signaling molecule cAMP is of particular interest because of its numerous cellular effects. However, to assess the biological relevance of GJ-mediated cAMP transfer, quantitative aspects must be determined. Here we employed cAMP indicators based on fluorescence resonance energy transfer (FRET) to study propagation of cAMP signals to neighbor cells through connexin43 (Cx43)-based gap junctions in Rat-1 cells quantitatively. Intracellular cAMP levels were selectively raised in single cells by either photorelease of caged cAMP or stimulation of G(s)-coupled receptors. cAMP elevations spread to adjacent cells within seconds in a Cx43-dependent manner. We determined that Rat-1 cells follow cAMP rises in surrounding monolayer cells to approx. 40% in amplitude. This degree of cAMP transfer sufficed to evoke a well-characterized response to cAMP in neighbor cells, i.e. the PKA-mediated phosphorylation of the ER transcription factor in A431 carcinoma cells. We conclude that contacting cells can cooperatively regulate cAMP-sensitive processes via gap junctional diffusion of cAMP.
authors.affiliation: Divisions of Cell Biology, The Netherlands Cancer Institute Plesmanlaan 121 1066 CX Amsterdam, The Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Ponsioen
authors.forename: Leonie
authors.initials: L
authors.lastname: van Zeijl
authors.forename: Wouter H
authors.initials: WH
authors.lastname: Moolenaar
authors.forename: Kees
authors.initials: K
authors.lastname: Jalink
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002450:Cell Communication; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics / Q000502:physiology*; D000242:Cyclic AMP / Q000032:analysis* / Q000378:metabolism*; D004058:Diffusion; D005347:Fibroblasts / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D017629:Gap Junctions / Q000502:physiology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D010782:Photolysis; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000819:agonists; D015398:Signal Transduction; D014157:Transcription Factors
chemical_list: D018031:Connexin 43; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases