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Ultrastructural analysis reveals cAMP-dependent enhancement of microvascular endothelial barrier functions via Rac1-mediated reorganization of intercellular junctions
- Source :
- The American journal of pathology. 178(5)
- Publication Year :
- 2010
-
Abstract
- Evidence exists that cAMP stabilizes the endothelial barrier, in part via activation of the small GTPase Rac1. However, despite the high medical relevance of this signaling pathway, the mechanistic effects on intercellular contacts on the ultrastructural level are largely unknown. In microvascular endothelial cell monolayers, in which increased cAMP strengthened barrier properties, similar to intact microvessels in vivo, both forskolin and rolipram (F/R) to increase cAMP and 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphorothioate (O-Me-cAMP) to stimulate exchange protein directly activated by cAMP/Ras proximate-1 (EPac/Rap 1) signaling enhanced transendothelial electrical resistance and induced activation of Rac1. Concurrently, augmented immunofluorescence intensity and linearization of signals at cell borders were observed for intercellular junction proteins VE-cadherin and claudin 5. Ultrastructural analysis of the intercellular contact zone architecture documented that exposure to F/R or O-Me-cAMP led to a significant increase in the proportion of contact sites displaying complex interdigitations of cell borders, in which membranes of neighboring cells were closely apposed over comparatively long distances; in addition, they were stabilized by numerous intercellular junctions. Interference with Rac1 activation by NSC-23766 completely abolished both barrier stabilization and contact zone reorganization in response to O-Me-cAMP, whereas F/R-mediated Rac1 activation and barrier enhancement were not affected by NSC-23766. In parallel experiments using macrovascular endothelium, increased cAMP failed to induce Rac1 activation, barrier enhancement, and contact zone reorganization. These results indicate that, in microvascular endothelium, Rac1-mediated alterations in contact zone architecture contribute to cAMP-induced barrier stabilization.
- Subjects :
- Male
rac1 GTP-Binding Protein
Endothelium
Vascular permeability
Biology
Cell junction
Pathology and Forensic Medicine
Capillary Permeability
chemistry.chemical_compound
Microscopy, Electron, Transmission
medicine
Cyclic AMP
Animals
Humans
Small GTPase
Claudin
Barrier function
Forskolin
Endothelial Cells
Regular Article
Cell biology
Rats
Endothelial stem cell
medicine.anatomical_structure
Intercellular Junctions
chemistry
Microvessels
Female
Signal Transduction
Subjects
Details
- ISSN :
- 15252191
- Volume :
- 178
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- The American journal of pathology
- Accession number :
- edsair.doi.dedup.....8c466e3eff688d9869c7c7da4cf49ee7