title: Bnip3 mediates doxorubicin-induced cardiac myocyte necrosis and mortality through changes in mitochondrial signaling.
abstract: Doxorubicin (DOX) is widely used for treating human cancers, but can induce heart failure through an undefined mechanism. Herein we describe a previously unidentified signaling pathway that couples DOX-induced mitochondrial respiratory chain defects and necrotic cell death to the BH3-only protein Bcl-2-like 19 kDa-interacting protein 3 (Bnip3). Cellular defects, including vacuolization and disrupted mitochondria, were observed in DOX-treated mice hearts. This coincided with mitochondrial localization of Bnip3, increased reactive oxygen species production, loss of mitochondrial membrane potential, mitochondrial permeability transition pore opening, and necrosis. Interestingly, a 3.1-fold decrease in maximal mitochondrial respiration was observed in cardiac mitochondria of mice treated with DOX. In vehicle-treated control cells undergoing normal respiration, the respiratory chain complex IV subunit 1 (COX1) was tightly bound to uncoupling protein 3 (UCP3), but this complex was disrupted in cells treated with DOX. Mitochondrial dysfunction induced by DOX was accompanied by contractile failure and necrotic cell death. Conversely, shRNA directed against Bnip3 or a mutant of Bnip3 defective for mitochondrial targeting abrogated DOX-induced loss of COX1-UCP3 complexes and respiratory chain defects. Finally, Bnip3(-/-) mice treated with DOX displayed relatively normal mitochondrial morphology, respiration, and mortality rates comparable to those of saline-treated WT mice, supporting the idea that Bnip3 underlies the cardiotoxic effects of DOX. These findings reveal a new signaling pathway in which DOX-induced mitochondrial respiratory chain defects and necrotic cell death are mutually dependent on and obligatorily linked to Bnip3 gene activation. Interventions that antagonize Bnip3 may prove beneficial in preventing mitochondrial injury and heart failure in cancer patients undergoing chemotherapy.
authors.affiliation: Department of Physiology and Pathophysiology.
authors.forename: Rimpy
authors.initials: R
authors.lastname: Dhingra
authors.affiliation: Department of Physiology and Pathophysiology.
authors.forename: Victoria
authors.initials: V
authors.lastname: Margulets
authors.affiliation: Department of Physiology and Pathophysiology.
authors.forename: Subir Roy
authors.initials: SR
authors.lastname: Chowdhury
authors.affiliation: Department of Anatomy and Cell Science.
authors.forename: James
authors.initials: J
authors.lastname: Thliveris
authors.affiliation: Department of Physiology and Pathophysiology, Department of Medicine, Faculty of Health Sciences, and.
authors.forename: Davinder
authors.initials: D
authors.lastname: Jassal
authors.affiliation: Department of Physiology and Pathophysiology, Department of Pharmacology and Therapeutics, Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, University of Manitoba, Winnipeg, MB, Canada R2H 2H6; and.
authors.forename: Paul
authors.initials: P
authors.lastname: Fernyhough
authors.affiliation: Center of Pharmacogenetics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110.
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Dorn
authors.affiliation: Department of Physiology and Pathophysiology, Department of Pharmacology and Therapeutics, Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, University of Manitoba, Winnipeg, MB, Canada R2H 2H6; and lorrie@sbrc.ca.
authors.forename: Lorrie A
authors.initials: LA
authors.lastname: Kirshenbaum
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D004317:Doxorubicin / Q000633:toxicity*; D004579:Electron Transport / Q000187:drug effects; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D000903:Antibiotics, Antineoplastic; C505650:BNIP3 protein, rat; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D004317:Doxorubicin
keywords: Bnip3; cell death; heart failure; mitochondria; ventricular myocytes