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Inducible HSP70 regulates superoxide dismutase-2 and mitochondrial oxidative stress in the endothelial cells from developing lungs. Am J Physiol Lung Cell Mol Physiol 2014 Feb 15;306(4):L351-60



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Pubmed Central ID




Scopus ID

2-s2.0-84894025712   28 Citations


Superoxide dismutase 2 (SOD-2) is synthesized in the cytosol and imported into the mitochondrial matrix, where it is activated and functions as the primary antioxidant for cellular respiration. The specific mechanisms that target SOD-2 to the mitochondria remain unclear. We hypothesize that inducible heat shock protein 70 (iHSP70) targets SOD-2 to the mitochondria via a mechanism facilitated by ATP, and this process is impaired in persistent pulmonary hypertension of the newborn (PPHN). We observed that iHSP70 interacts with SOD-2 and targets SOD-2 to the mitochondria. Interruption of iHSP70-SOD-2 interaction with 2-phenylethylenesulfonamide-μ (PFT-μ, a specific inhibitor of substrate binding to iHSP70 COOH terminus) and siRNA-mediated knockdown of iHSP70 expression disrupted SOD-2 transport to mitochondria. Increasing intracellular ATP levels by stimulation of respiration with CaCl2 facilitated the mitochondrial import of SOD-2, increased SOD-2 activity, and decreased the mitochondrial superoxide (O2(·-)) levels in PPHN pulmonary artery endothelial cells (PAEC) by promoting iHSP70-SOD-2 dissociation at the outer mitochondrial membrane. In contrast, oligomycin, an inhibitor of mitochondrial ATPase, decreased SOD-2 expression and activity and increased O2(·-) levels in the mitochondria of control PAEC. The basal ATP levels and degree of iHSP70-SOD-2 dissociation were lower in PPHN PAEC and lead to increased SOD-2 degradation in cytosol. In normal pulmonary arteries (PA), PFT-μ impaired the relaxation response of PA rings in response to nitric oxide (NO) donor, S-nitroso-N-acetyl-penicillamine. Pretreatment with Mito-Q, a mitochondrial targeted O2(·-) scavenger, restored the relaxation response in PA rings pretreated with PFT-μ. Our observations suggest that iHSP70 chaperones SOD-2 to the mitochondria. Impaired SOD-2-iHSP70 dissociation decreases SOD-2 import and contributes to mitochondrial oxidative stress in PPHN.

Author List

Afolayan AJ, Teng RJ, Eis A, Rana U, Broniowska KA, Corbett JA, Pritchard K, Konduri GG


Adeleye James Afolayan MD Assistant Professor in the Pediatrics department at Medical College of Wisconsin
John A. Corbett PhD Chair, Professor in the Biochemistry department at Medical College of Wisconsin
Girija Ganesh Konduri MD Chief, Professor in the Pediatrics department at Medical College of Wisconsin
Kirkwood A. Pritchard PhD Professor in the Surgery department at Medical College of Wisconsin
Ru-Jeng Teng MD Associate Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adenosine Triphosphate
Cells, Cultured
Endothelial Cells
HSP70 Heat-Shock Proteins
Hydrogen Peroxide
Infant, Newborn
Oxidative Phosphorylation
Oxidative Stress
Persistent Fetal Circulation Syndrome
Protein Transport
Pulmonary Artery
jenkins-FCD Prod-466 5b81815b8b3d1f46bfec16512ed5f574613f59c5