title: Regulation of mitochondrial oxidative stress by β-arrestins in cultured human cardiac fibroblasts.
abstract: Oxidative stress in cardiac fibroblasts (CFs) promotes transformation to myofibroblasts and collagen synthesis leading to myocardial fibrosis, a precursor to heart failure (HF). NADPH oxidase 4 (Nox4) is a major source of cardiac reactive oxygen species (ROS); however, mechanisms of Nox4 regulation are unclear. β-arrestins are scaffold proteins that signal in G-protein-dependent and -independent pathways; for example, in ERK activation. We hypothesize that β-arrestins regulate oxidative stress in a Nox4-dependent manner and increase fibrosis in HF. CFs were isolated from normal and failing adult human left ventricles. Mitochondrial ROS/superoxide production was quantitated using MitoSox. β-arrestin and Nox4 expressions were manipulated using adenoviral overexpression or short interfering RNA (siRNA)-mediated knockdown. Mitochondrial oxidative stress and Nox4 expression in CFs were significantly increased in HF. Nox4 knockdown resulted in inhibition of mitochondrial superoxide production and decreased basal and TGF-β-stimulated collagen and α-SMA expression. CF β-arrestin expression was upregulated fourfold in HF. β-arrestin knockdown in failing CFs decreased ROS and Nox4 expression by 50%. β-arrestin overexpression in normal CFs increased mitochondrial superoxide production twofold. These effects were prevented by inhibition of either Nox or ERK. Upregulation of Nox4 seemed to be a primary mechanism for increased ROS production in failing CFs, which stimulates collagen deposition. β-arrestin expression was upregulated in HF and plays an important and newly identified role in regulating mitochondrial superoxide production via Nox4. The mechanism for this effect seems to be ERK-mediated. Targeted inhibition of β-arrestins in CFs might decrease oxidative stress as well as pathological cardiac fibrosis.
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Philip
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Md Abdur
authors.initials: MA
authors.lastname: Razzaque
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Mei
authors.initials: M
authors.lastname: Han
authors.affiliation: Section of Cardiac and Thoracic Surgery, University of Chicago Medical Center, Chicago, IL 60637, USA.
authors.forename: Jinju
authors.initials: J
authors.lastname: Li
authors.affiliation: Section of Cardiac and Thoracic Surgery, University of Chicago Medical Center, Chicago, IL 60637, USA.
authors.forename: Tiju
authors.initials: T
authors.lastname: Theccanat
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
authors.forename: Xianyao
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA akhter@surgery.wisc.edu.
authors.forename: Shahab A
authors.initials: SA
authors.lastname: Akhter
mesh_terms: D019390:Arrestins / Q000378:metabolism*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D006333:Heart Failure / Q000473:pathology; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000473:pathology*; D058628:Myofibroblasts / Q000187:drug effects / Q000378:metabolism; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D016212:Transforming Growth Factor beta; D000071557:beta-Arrestins; D013481:Superoxides; D003094:Collagen; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Cardiac fibroblast; Collagen; Heart failure; Myocardial fibrosis; NADPH oxidase; Oxidative stress; β-arrestin