title: Heat Shock Protein 70 Prevents Hyperoxia-Induced Disruption of Lung Endothelial Barrier via Caspase-Dependent and AIF-Dependent Pathways.
abstract: Exposure of pulmonary artery endothelial cells (PAECs) to hyperoxia results in a compromise in endothelial monolayer integrity, an increase in caspase-3 activity, and nuclear translocation of apoptosis-inducing factor (AIF), a marker of caspase-independent apoptosis. In an endeavor to identify proteins involved in hyperoxic endothelial injury, we found that the protein expression of heat-shock protein 70 (Hsp70) was increased in hyperoxic PAECs. The hyperoxia-induced Hsp70 protein expression is from hspA1B gene. Neither inhibition nor overexpression of Hsp70 affected the first phase barrier disruption of endothelial monolayer. Nevertheless, inhibition of Hsp70 by using the Hsp70 inhibitor KNK437 or knock down Hsp70 using siRNA exaggerated and overexpression of Hsp70 prevented the second phase disruption of lung endothelial integrity. Moreover, inhibition of Hsp70 exacerbated and overexpression of Hsp70 prevented hyperoxia-induced apoptosis, caspase-3 activation, and increase in nuclear AIF protein level in PAECs. Furthermore, we found that Hsp70 interacted with AIF in the cytosol in hyperoxic PAECs. Inhibition of Hsp70/AIF association by KNK437 correlated with increased nuclear AIF level and apoptosis in KNK437-treated PAECs. Finally, the ROS scavenger NAC prevented the hyperoxia-induced increase in Hsp70 expression and reduced the interaction of Hsp70 with AIF in hyperoxic PAECs. Together, these data indicate that increased expression of Hsp70 plays a protective role against hyperoxia-induced lung endothelial barrier disruption through caspase-dependent and AIF-dependent apoptotic pathways. Association of Hsp70 with AIF prevents AIF nuclear translocation, contributing to the protective effect of Hsp70 on hyperoxia-induced endothelial apoptosis. The hyperoxia-induced increase in Hsp70 expression and Hsp70/AIF interaction is contributed to ROS formation.
authors.affiliation: Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Kondrikov
authors.affiliation: Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America; Vascular Biology Center, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Fulton
authors.affiliation: Department of Cell Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America; Research Service, Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia 30912, United States of America.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America; Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America; Vascular Biology Center, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States of America; Research Service, Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia 30912, United States of America.
authors.forename: Yunchao
authors.initials: Y
authors.lastname: Su
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D001559:Benzhydryl Compounds / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D002417:Cattle; D015687:Cell Hypoxia; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D011651:Pulmonary Artery / Q000166:cytology; D011760:Pyrrolidinones / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D051033:Apoptosis Inducing Factor; D001559:Benzhydryl Compounds; D018840:HSP70 Heat-Shock Proteins; C410027:KNK 437; D011760:Pyrrolidinones; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D053148:Caspase 3