title: Estrogen-dependent inhibition of dextrose-induced endoplasmic reticulum stress and superoxide generation in endothelial cells.
abstract: Increased oxidative stress and endoplasmic reticulum stress (ER stress) have been implicated in atherosclerosis. Estrogens have potent antioxidant activity but their effects on ER stress have not been well studied. Therefore, we studied the effects of estradiol and related sex steroids on dextrose-induced ER stress and superoxide (SO) generation in human umbilical vein endothelial cells (HUVECs). Oxidative stress was measured using hydroethidine fluorescence and MCLA chemiluminescence. ER stress was measured with an ER stress-sensitive secreted alkaline phosphatase (ES-TRAP) assay and by Western blot analysis of the expression of GRP78, JNK1, and phosphorylated JNK1, markers for ER stress. A supraphysiological dextrose concentration (27.5mM) increased ER stress and SO generation compared to treatment with a physiological concentration (5.5mM) of dextrose. In the presence of estradiol or testosterone (T), ER stress and SO generation were significantly reduced. In contrast to T-treated cells, dihydrotestosterone and 5-methyltestosterone were ineffective at alleviating ER stress or SO generation. When HUVECs were treated with T and the aromatase inhibitor 4-hydroxy-4-androstene-3,17-dione, T was no longer effective at suppressing ER stress or inhibiting SO generation. Changes in GRP78 expression and JNK activity in HUVECs support the results obtained in the ES-TRAP assay. These results indicate that dextrose-induced endoplasmic reticulum stress and superoxide generation are reversed by estradiol and testosterone; however, the latter requires aromatase-dependent conversion to estradiol.
authors.affiliation: Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Florida College of Medicine, Jacksonville, FL 32209, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Haas
authors.forename: Prafull
authors.initials: P
authors.lastname: Raheja
authors.forename: Sarada
authors.initials: S
authors.lastname: Jaimungal
authors.forename: Mae
authors.initials: M
authors.lastname: Sheikh-Ali
authors.forename: Arshag D
authors.initials: AD
authors.lastname: Mooradian
mesh_terms: D000735:Androstenedione / Q000031:analogs & derivatives / Q000494:pharmacology; D047072:Aromatase Inhibitors / Q000494:pharmacology; D050197:Atherosclerosis / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D042783:Endothelial Cells / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013739:Testosterone / Q000494:pharmacology*; D056811:Unfolded Protein Response / Q000187:drug effects
chemical_list: D047072:Aromatase Inhibitors; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D013481:Superoxides; D013739:Testosterone; D000735:Androstenedione; D004958:Estradiol; D048670:MAP Kinase Kinase 4; D005947:Glucose; C014594:formestane