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Hyperoxia Causes Mitochondrial Fragmentation in Pulmonary Endothelial Cells by Increasing Expression of Pro-Fission Proteins. Arterioscler Thromb Vasc Biol 2018 03;38(3):622-635

Date

02/09/2018

Pubmed ID

29419407

Pubmed Central ID

PMC5823793

DOI

10.1161/ATVBAHA.117.310605

Scopus ID

2-s2.0-85047900228   3 Citations

Abstract

OBJECTIVE: We explored mechanisms that alter mitochondrial structure and function in pulmonary endothelial cells (PEC) function after hyperoxia.

APPROACH AND RESULTS: Mitochondrial structures of PECs exposed to hyperoxia or normoxia were visualized and mitochondrial fragmentation quantified. Expression of pro-fission or fusion proteins or autophagy-related proteins were assessed by Western blot. Mitochondrial oxidative state was determined using mito-roGFP. Tetramethylrhodamine methyl ester estimated mitochondrial polarization in treatment groups. The role of mitochondrially derived reactive oxygen species in mt-fragmentation was investigated with mito-TEMPOL and mitochondrial DNA (mtDNA) damage studied by using ENDO III (mt-tat-endonuclease III), a protein that repairs mDNA damage. Drp-1 (dynamin-related protein 1) was overexpressed or silenced to test the role of this protein in cell survival or transwell resistance. Hyperoxia increased fragmentation of PEC mitochondria in a time-dependent manner through 48 hours of exposure. Hyperoxic PECs exhibited increased phosphorylation of Drp-1 (serine 616), decreases in Mfn1 (mitofusion protein 1), but increases in OPA-1 (optic atrophy 1). Pro-autophagy proteins p62 (LC3 adapter-binding protein SQSTM1/p62), PINK-1 (PTEN-induced putative kinase 1), and LC3B (microtubule-associated protein 1A/1B-light chain 3) were increased. Returning cells to normoxia for 24 hours reversed the increased mt-fragmentation and changes in expression of pro-fission proteins. Hyperoxia-induced changes in mitochondrial structure or cell survival were mitigated by antioxidants mito-TEMPOL, Drp-1 silencing, or inhibition or protection by the mitochondrial endonuclease ENDO III. Hyperoxia induced oxidation and mitochondrial depolarization and impaired transwell resistance. Decrease in resistance was mitigated by mito-TEMPOL or ENDO III and reproduced by overexpression of Drp-1.

CONCLUSIONS: Because hyperoxia evoked mt-fragmentation, cell survival and transwell resistance are prevented by ENDO III and mito-TEMPOL and Drp-1 silencing, and these data link hyperoxia-induced mt-DNA damage, Drp-1 expression, mt-fragmentation, and PEC dysfunction.

Author List

Ma C, Beyer AM, Durand M, Clough AV, Zhu D, Norwood Toro L, Terashvili M, Ebben JD, Hill RB, Audi SH, Medhora M, Jacobs ER

Authors

Andreas M. Beyer PhD Associate Professor in the Medicine department at Medical College of Wisconsin
Ronald Blake Hill PhD Professor in the Biochemistry department at Medical College of Wisconsin
Elizabeth R. Jacobs MD Associate Dean, Professor in the Medicine department at Medical College of Wisconsin
Meetha M. Medhora PhD Professor in the Radiation Oncology department at Medical College of Wisconsin




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

Animals
Antioxidants
Dynamins
Endothelial Cells
Hyperoxia
Mitochondria
Mitochondrial Dynamics
Mitochondrial Proteins
Oxidative Stress
Oxygen
Pulmonary Artery
Rats
Reactive Oxygen Species
Up-Regulation
jenkins-FCD Prod-400 0f9a74600e4e79798f8fa6f545ea115f3dd948b2