title: Adropin reduces paracellular permeability of rat brain endothelial cells exposed to ischemia-like conditions.
abstract: Adropin is a peptide encoded by the energy homeostasis associated gene (Enho) and plays a critical role in the regulation of lipid metabolism, insulin sensitivity, and endothelial function. Little is known of the effects of adropin in the brain and whether this peptide modulates ischemia-induced blood-brain barrier (BBB) injury. Here, we used an in vitro BBB model of rat brain microvascular endothelial cells (RBE4) and hypothesized that adropin would reduce endothelial permeability during ischemic conditions. To mimic ischemic conditions in vitro, RBE4 cell monolayers were subjected to 16h hypoxia/low glucose (HLG). This resulted in a significant increase in paracellular permeability to FITC-labeled dextran (40kDa), a dramatic upregulation of vascular endothelial growth factor (VEGF), and the loss of junction proteins occludin and VE-cadherin. Notably, HLG also significantly decreased Enho expression and adropin levels. Treatment of RBE4 cells with synthetic adropin (1, 10 and 100ng/ml) concentration-dependently reduced endothelial permeability after HLG, but this was not mediated through protection to junction proteins or through reduced levels of VEGF. We found that HLG dramatically increased myosin light chain 2 (MLC2) phosphorylation in RBE4 cells, which was significantly reduced by adropin treatment. We also found that HLG significantly increased Rho-associated kinase (ROCK) activity, a critical upstream effector of MLC2 phosphorylation, and that adropin treatment attenuated that effect. These data indicate that treatment with adropin reduces endothelial cell permeability after HLG insult by inhibition of the ROCK-MLC2 signaling pathway. These promising findings suggest that adropin protects against endothelial barrier dysfunction during ischemic conditions.
authors.affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Changjun
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: DeMars
authors.affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Kimberly E
authors.initials: KE
authors.lastname: Hawkins
authors.affiliation: Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA. Electronic address: ecandelario@ufl.edu.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Candelario-Jalil
mesh_terms: D022005:Adherens Junctions / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000378:metabolism; D002545:Brain Ischemia / Q000503:physiopathology*; D015820:Cadherins / Q000378:metabolism; D002199:Capillary Permeability / Q000187:drug effects*; D024722:Cardiac Myosins / Q000037:antagonists & inhibitors*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D018994:Myosin Light Chains / Q000037:antagonists & inhibitors*; D062793:Occludin / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D001798:Blood Proteins; D015820:Cadherins; D024722:Cardiac Myosins; D005947:Glucose; D018994:Myosin Light Chains; D062793:Occludin; D010455:Peptides; D042461:Vascular Endothelial Growth Factor A; D054460:rho-Associated Kinases; D000099152:Cadherin 5; C586182:ENHO protein, rat; C107184:myosin light chain 2
keywords: Adherens junction protein; Adropin; Hypoxia; Myosin light chain 2; Paracellular permeability; Rho-associated kinase; Tight junction proteins