title: Regulation of cellular oxidative stress and apoptosis by G protein-coupled receptor kinase-2; The role of NADPH oxidase 4.
abstract: Cardiac myocyte oxidative stress and apoptosis are considered important mechanisms for the development of heart failure (HF). Chronic HF is characterized by increased circulating catecholamines to augment cardiac output. Long-term stimulation of myocardial β-adrenergic receptors (β-ARs) is deleterious in cardiac myocytes, however, the potential mechanisms underlying increased cell death are unclear. We hypothesize that GRK2, a critical regulator of myocardial β-AR signaling, plays an important role in mediating cellular oxidative stress and apoptotic cell death in response to β-agonist stimulation. Stimulation of H9c2 cells with a non-selective β-agonist, isoproterenol (Iso) caused increased oxidative stress and apoptosis. There was also increased Nox4 expression, but no change in Nox2, the primary NADPH isoforms and major sources of ROS generation in cardiac myocytes. Adenoviral-mediated overexpression of GRK2 led to similar increases in ROS production and apoptosis as seen with Iso stimulation. These increases in oxidative stress were abolished by pre-treatment with the non-specific Nox inhibitor, apocynin, or siRNA knockdown of Nox4. Adenoviral-mediated expression of a GRK2 inhibitor prevented ROS production and apoptosis in response to Iso stimulation. β-Arrestins are signaling proteins that function downstream of GRK2 in β-AR uncoupling. Adenoviral-mediated overexpression of β-arrestins increased ROS production and Nox4 expression. Chronic β-agonist stimulation in mice increased Nox4 expression and apoptosis compared to PBS or AngII treatment. These data demonstrate that GRK2 may play an important role in regulating oxidative stress and apoptosis in cardiac myocytes and provides an additional novel mechanism for the beneficial effects of cardiac-targeted GRK2 inhibition to prevent the development of HF.
authors.affiliation: Department of Surgery, Section of Cardiac and Thoracic Surgery, University of Chicago Medical Center, Chicago, IL, United States.
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, United States.
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, United States.
authors.forename: Abdur M
authors.initials: AM
authors.lastname: Razzaque
authors.affiliation: Department of Surgery, Section of Cardiac and Thoracic Surgery, University of Chicago Medical Center, Chicago, IL, United States.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Ludmer
authors.affiliation: Department of Surgery, Section of Cardiac and Thoracic Surgery, University of Chicago Medical Center, Chicago, IL, United States.
authors.forename: Jinju
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Surgery, Division of Cardiothoracic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.
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, United States. Electronic address: akhter@surgery.wisc.edu.
authors.forename: Shahab A
authors.initials: SA
authors.lastname: Akhter
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019390:Arrestins; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000235:genetics / Q000378:metabolism; D006333:Heart Failure / Q000378:metabolism / Q000473:pathology; D007545:Isoproterenol / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000737:chemistry / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000071557:beta-Arrestins
chemical_list: D000098:Acetophenones; D000318:Adrenergic beta-Agonists; D019390:Arrestins; D008562:Membrane Glycoproteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D011943:Receptors, Adrenergic, beta; D000071557:beta-Arrestins; D000804:Angiotensin II; D012243:Rhodopsin; C056165:acetovanillone; D000242:Cyclic AMP; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498911:Nox4 protein, rat; D054769:G-Protein-Coupled Receptor Kinase 2; D007545:Isoproterenol
keywords: G protein-coupled receptor kinases; Heart failure; NADPH oxidase; Oxidative stress