Histamine causes endothelial barrier disruption via Ca2+-mediated RhoA activation and tension at adherens junctions

• Published in: Scientific reports 2018-09, Vol.8 (1), p.1-14, Article 13229
• Main Authors: Kugelmann, Daniela, Rotkopf, Lukas Thomas, Radeva, Mariya Yosifova, Garcia-Ponce, Alexander, Walter, Elias, Waschke, Jens
• Format: Article
• Language: English
• Subjects: 13; 14; 631/80/79/2027; 692/699/75; 9/10; Adherens junctions; Calcium influx; Calcium signalling; Cell junctions; Chelation; Conformation; Endothelial cells; Fluorescence resonance energy transfer; Histamine; Humanities and Social Sciences; Inactivation; Microvasculature; multidisciplinary; Permeability; Rac1 protein; Rho-associated kinase; RhoA protein; Science; Science (multidisciplinary); Tension; Thrombin; Translocation; Vinculin; α-Catenin
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-31408-3

During inflammation, the disruption of the endothelial barrier leads to increased microvascular permeability. Whether tension along cell junctions contributes to histamine-induced endothelial barrier disruption remains unknown. Rapid Ca 2+ influx induced by both histamine and thrombin was accompanied by endothelial barrier breakdown revealed as drop of transendothelial electric resistance in primary human microvascular endothelial cells. Interestingly, GLISA measurements revealed activation of RhoA but not inactivation of Rac1 at the time-point of barrier breakdown. FRET measurements showed activation of RhoA at intercellular junctions after both thrombin and histamine exposure. Breakdown coincided with increased stress fiber formation but not with translocation of vinculin, which was located along junctions in the resting state similar to postcapillary venules ex vivo . Moreover, increased tension at AJs was indicated by immunostaining with a conformation-sensitive antibody targeting the α18-subunit of α-catenin. Ca 2+ chelation by BAPTA-AM and ROCK1 inhibition by Y27632 abolished both increase of tension along AJs as well as barrier dysfunction. Moreover, BAPTA-AM decreased RhoA activation following histamine stimulation, indicating a key role of Ca 2+ signaling in barrier breakdown. Taken together, in response to histamine, Ca 2+ via RhoA/ROCK activation along endothelial adherens junctions (AJs) appears to be critical for barrier disruption and presumably correlated with enhanced tension. However, vinculin appears not to be critical in this process.