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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

Date

01/01/2014

Pubmed ID

24375796

Pubmed Central ID

PMC3920226

DOI

10.1152/ajplung.00264.2013

Scopus ID

2-s2.0-84894025712   25 Citations

Abstract

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

Authors

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
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
Animals
Cells, Cultured
Endothelial Cells
HSP70 Heat-Shock Proteins
Humans
Hydrogen Peroxide
Infant, Newborn
Lung
Mitochondria
Oxidative Phosphorylation
Oxidative Stress
Persistent Fetal Circulation Syndrome
Protein Transport
Proteolysis
Pulmonary Artery
Sheep
jenkins-FCD Prod-400 0f9a74600e4e79798f8fa6f545ea115f3dd948b2