Title

SOD2 deficiency in cardiomyocytes defines defective mitochondrial bioenergetics as a cause of lethal dilated cardiomyopathy

Authors

Sudha Sharma, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Susmita Bhattarai, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Hosne Ara, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Grace Sun, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Daret K. St Clair, Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, Lexington, KY, USA.
Md Shenuarin Bhuiyan, Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Christopher Kevil, Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Megan N. Watts, Division of Cardiology, Department of Medicine, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Paari Dominic, Division of Cardiology, Department of Medicine, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Takahiko Shimizu, National Center for Geriatrics and Gerontology, 7-430, Morioka, Obu Aichi, Japan.
Kevin J. McCarthy, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Hong Sun, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Manikandan Panchatcharam, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA. Electronic address: mpanch@lsuhsc.edu.
Sumitra Miriyala, Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA. Electronic address: smiriy@lsuhsc.edu.

Document Type

Article

Publication Date

10-1-2020

Abstract

Electrophilic aldehyde (4-hydroxynonenal; 4-HNE), formed after lipid peroxidation, is a mediator of mitochondrial dysfunction and implicated in both the pathogenesis and the progression of cardiovascular disease. Manganese superoxide dismutase (MnSOD), a nuclear-encoded antioxidant enzyme, catalyzes the dismutation of superoxide radicals (O) in mitochondria. To study the role of MnSOD in the myocardium, we generated a cardiomyocyte-specific SOD2 (SOD2Δ) deficient mouse strain. Unlike global SOD2 knockout mice, SOD2Δ mice reached adolescence; however, they die at ~4 months of age due to heart failure. Ultrastructural analysis of SOD2Δ hearts revealed altered mitochondrial architecture, with prominent disruption of the cristae and vacuole formation. Noninvasive echocardiographic measurements in SOD2 mice showed dilated cardiomyopathic features such as decreased ejection fraction and fractional shortening along with increased left ventricular internal diameter. An increased incidence of ventricular tachycardia was observed during electrophysiological studies of the heart in SOD2Δ mice. Oxidative phosphorylation (OXPHOS) measurement using a Seahorse XF analyzer in SOD2Δ neonatal cardiomyocytes and adult cardiac mitochondria displayed reduced O consumption, particularly during basal conditions and after the addition of FCCP (H ionophore/uncoupler), compared to that in SOD2fl hearts. Measurement of extracellular acidification (ECAR) to examine glycolysis in these cells showed a pattern precisely opposite that of the oxygen consumption rate (OCR) among SOD2Δ mice compared to their SOD2 littermates. Analysis of the activity of the electron transport chain complex identified a reduction in Complex I and Complex V activity in SOD2Δ compared to SOD2fl mice. We demonstrated that a deficiency of SOD2 increases reactive oxygen species (ROS), leading to subsequent overproduction of 4-HNE inside mitochondria. Mechanistically, proteins in the mitochondrial respiratory chain complex and TCA cycle (NDUFS2, SDHA, ATP5B, and DLD) were the target of 4-HNE adduction in SOD2Δ hearts. Our findings suggest that the SOD2 mediated 4-HNE signaling nexus may play an important role in cardiomyopathy.

Publication Source (Journal or Book title)

Redox biology

First Page

101740

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