title: Hypoxic preconditioning protects microvascular endothelial cells against hypoxia/reoxygenation injury by attenuating endoplasmic reticulum stress.
abstract: Endothelial cells (ECs) are directly exposed to hypoxia and contribute to injury during myocardial ischemia/reperfusion. Hypoxic preconditioning (HPC) protects ECs against hypoxia injury. This study aimed to explore whether HPC attenuates hypoxia/reoxygenation (H/R) injury by suppressing excessive endoplasmic reticulum stress (ERS) in cultured microvascular ECs (MVECs) from rat heart. MVECs injury was measured by lactate dehydrogenase (LDH) leakage, cytoskeleton destruction, and apoptosis. Expression of glucose regulating protein 78 (GRP78) and C/EBP homologous protein (CHOP), activation of caspase-12 (pro-apoptosis factors) and phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) were detected by western blot analysis. HPC attenuated H/R-induced LDH leakage, cytoskeleton destruction, and cell apoptosis, as shown by flow cytometry, Bax/Bcl-2 ratio, caspase-3 activation and terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling. HPC suppressed H/R-induced ERS, as shown by a decrease in expression of GRP78 and CHOP, and caspase-12 activation. HPC enhanced p38 MAPK phosphorylation but decreased that of protein kinase R-like ER kinase (PERK, upstream regulator of CHOP). SB202190 (an inhibitor of p38 MAPK) abolished HPC-induced cytoprotection, downregulation of GRP78 and CHOP, and activation of caspase-12, as well as PERK phosphorylation. HPC may protect MVECs against H/R injury by suppressing CHOP-dependent apoptosis through p38 MAPK mediated downregulation of PERK activation.
authors.affiliation: Department of Out-patient, Chinese PLA General Hospital, Beijing, 100853, China. wuxudong60@yahoo.com.cn
authors.forename: Xu-Dong
authors.initials: XD
authors.lastname: Wu
authors.forename: Zhen-Ying
authors.initials: ZY
authors.lastname: Zhang
authors.forename: Sheng
authors.initials: S
authors.lastname: Sun
authors.forename: Yu-Zhen
authors.initials: YZ
authors.lastname: Li
authors.forename: Xiao-Reng
authors.initials: XR
authors.lastname: Wang
authors.forename: Xiu-Qin
authors.initials: XQ
authors.lastname: Zhu
authors.forename: Wei-Hong
authors.initials: WH
authors.lastname: Li
authors.forename: Xiu-Hua
authors.initials: XH
authors.lastname: Liu
mesh_terms: D000818:Animals; D017209:Apoptosis; D015687:Cell Hypoxia; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology; D005260:Female; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000517:prevention & control*; D019892:eIF-2 Kinase / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP
chemical_list: D006360:Heat-Shock Proteins; D019892:eIF-2 Kinase; D048051:p38 Mitogen-Activated Protein Kinases; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP