Exendin-4 promotes endothelial barrier enhancement via PKA- and Epac1-dependent Rac1 activation.
Among emerging antidiabetic agents, glucagon-like peptide-1 (GLP-1)-based therapies carry special cardiovascular implications, exerting both direct and indirect effects. The control of vascular permeability is of pivotal importance in vascular pathologies. The objective of the present study was to determine the effect of GLP-1 on endothelial barrier function and assess the underlying mechanism(s). Here we show for the first time that the stable GLP-1 analog exendin-4 attenuated the leakage of subcutaneous blood vessels in mice indexed by dye extravasation caused by injections of thrombin. Moreover, in cultured endothelial cells, exendin-4 significantly prevented the thrombin-induced FITC-dextran permeability of endothelial monolayers via GLP-1 receptor. Immunofluorescence microscopy reveals that exendin-4 abrogates detrimental effects of thrombin on VE-cadherin and the F-actin cytoskeleton, with decreased stress fiber and gap formation. Importantly, exendin-4 reduced thrombin-induced tyrosine phosphorylation of VE-cadherin at Y731 and Y658. Moreover, small GTPase Rac1 was significantly activated as a result of exendin-4 treatment. The efficacy of exendin-4 to counteract the barrier-compromising effect of thrombin was blunted when Rac1 was inactivated by Rac1 inhibitor NSC-23766. Inhibition of PKA activity or small-interfering RNA for exchange protein directly activated by cAMP 1 (Epac1) decreased exendin-4-induced Rac1 activation and barrier enhancement, indicating the participation of both PKA and Epac1 in the barrier-stabilizing effect of exendin-4 elicited on thrombin-impaired barrier function. Thus, our findings have uncovered an unpredicted role for exendin-4 in the coordination of vascular permeability and clarified the molecular underpinnings that contribute to barrier restoration initiated by exendin-4.
Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China.
Ai Q
AQ
Li
Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China.
Liang
L
Zhao
Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China.
Teng F
TF
Zhou
Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China.
Meng Q
MQ
Zhang
Institute of Cardiovascular Science, and Key Laboratory of Molecular Cardiovascular Science of Ministry of Education, Peking University Health Science Center, Beijing, China xmqin@bjmu.edu.cn.
Xiao M
XM
Qin
D000199:Actins / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002199:Capillary Permeability / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D000077270:Exenatide; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism; D000067757:Glucagon-Like Peptide-1 Receptor; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000378:metabolism*; D018027:Receptors, Glucagon / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism; D014688:Venoms / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D000099152:Cadherin 5
D000199:Actins; D015703:Antigens, CD; D015820:Cadherins; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D003911:Dextrans; D000077270:Exenatide; D016650:Fluorescein-5-isothiocyanate; D052216:Glucagon-Like Peptide 1; D000067757:Glucagon-Like Peptide-1 Receptor; D020662:Guanine Nucleotide Exchange Factors; D010455:Peptides; D018027:Receptors, Glucagon; D013917:Thrombin; D014688:Venoms; D020830:rac1 GTP-Binding Protein; D000099152:Cadherin 5; C000593833:GLP1R protein, human; C000593834:Glp1r protein, mouse; C015219:fluorescein isothiocyanate dextran
Rac1; VE-cadherin; protein kinase A