Abstract
Extracellular beta-NAD is known to elevate intracellular levels of calcium ions, inositol 1,4,5-trisphate and cAMP. Recently, beta-NAD was identified as an agonist for P2Y1 and P2Y11 purinergic receptors. Since beta-NAD can be released extracellularly from endothelial cells (EC), we have proposed its involvement in the regulation of EC permeability. Here we show, for the first time, that endothelial integrity can be enhanced in EC endogenously expressing beta-NAD-activated purinergic receptors upon beta-NAD stimulation. Our data demonstrate that extracellular beta-NAD increases the transendothelial electrical resistance (TER) of human pulmonary artery EC (HPAEC) monolayers in a concentration-dependent manner indicating endothelial barrier enhancement. Importantly, beta-NAD significantly attenuated thrombin-induced EC permeability as well as the barrier-compromising effects of Gram-negative and Gram-positive bacterial toxins representing the barrier-protective function of beta-NAD. Immunofluorescence microscopy reveals more pronounced staining of cell-cell junctional protein VE-cadherin at the cellular periphery signifying increased tightness of the cell-cell contacts after beta-NAD stimulation. Interestingly, inhibitory analysis (pharmacological antagonists and receptor sequence specific siRNAs) indicates the participation of both P2Y1 and P2Y11 receptors in beta-NAD-induced TER increase. beta-NAD-treatment attenuates the lipopolysaccharide (LPS)-induced phosphorylation of myosin light chain (MLC) indicating its involvement in barrier protection. Our studies also show the involvement of cAMP-dependent protein kinase A and EPAC1 pathways as well as small GTPase Rac1 in beta-NAD-induced EC barrier enhancement. With these results, we conclude that beta-NAD regulates the pulmonary EC barrier integrity via small GTPase Rac1- and MLCP- dependent signaling pathways.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
