title: A PGC-1α-Mediated Transcriptional Network Maintains Mitochondrial Redox and Bioenergetic Homeostasis against Doxorubicin-Induced Toxicity in Human Cardiomyocytes: Implementation of TT21C.
abstract: Chemical toxicity testing is fast moving in a direction that relies increasingly on cell-basedin vitroassays anchored on toxicity pathways according to the toxicity testing in the 21st century vision. Identifying points of departure (POD) via these assays and revealing their mechanistic underpinnings via computational modeling of the relevant pathways are critical and challenging steps. Here we used doxorubicin (DOX) as a prototype chemical to study mitochondrial toxicity in human AC16 cells. Mitochondrial toxicity has been linked to cardiovascular risk of DOX, which has limited its clinical use as an antitumor drug. Ourin vitrostudy revealed a well-defined POD concentration of DOX below which adaptive induction of proliferator-activated receptor-γ coactivator-1α (PGC-1α) -mediated mitochondrial genes, including NRF-1, MnSOD, UCP2, and COX1, concurred with negligible changes in mitochondrial superoxide and cytotoxicity. At higher DOX concentrations adversity became significant with elevated superoxide and suppressed ATP levels. A computational model was formulated to simulate the PGC-1α-mediated transcriptional network comprising multiple negative feedback loops that underlie redox and bioenergetics homeostasis in the mitochondrion. The model recapitulated the transition phase from adaptive to adverse responses, supporting the notion that saturated induction of PGC-1α-mediated gene network underpins POD. The model further predicts (follow-up experiments verified) that silencing PGC-1α compromises the adaptive function of the transcriptional network, leading to disruption of mitochondria and cytotoxicity at lower DOX concentrations. In summary, our study demonstrates that combining pathway-focusedin vitroassays and computational simulation of relevant biochemical network is synergistic for understanding dose-response behaviors in the low-dose region and identifying POD.
authors.affiliation: *Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China; pengsq@hotmail.com.
authors.forename: Haitao
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA; and.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: *Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China;
authors.forename: Jiabin
authors.initials: J
authors.lastname: Guo
authors.affiliation: *Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China;
authors.forename: Tingfen
authors.initials: T
authors.lastname: Zhang
authors.affiliation: *Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China;
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Unilever Safety and Environmental Assurance Center, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK.
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.affiliation: Unilever Safety and Environmental Assurance Center, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: White
authors.affiliation: Unilever Safety and Environmental Assurance Center, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Carmichael
authors.affiliation: Unilever Safety and Environmental Assurance Center, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK.
authors.forename: Carl
authors.initials: C
authors.lastname: Westmoreland
authors.affiliation: *Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China; pengsq@hotmail.com.
authors.forename: Shuangqing
authors.initials: S
authors.lastname: Peng
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D056915:DNA Copy Number Variations / Q000187:drug effects; D004272:DNA, Mitochondrial / Q000235:genetics; D004317:Doxorubicin / Q000633:toxicity*; D053263:Gene Regulatory Networks / Q000187:drug effects*; D006706:Homeostasis / Q000187:drug effects*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / Q000235:genetics*; D012313:RNA / Q000235:genetics; D018675:Toxicity Tests / Q000379:methods* / Q000639:trends
chemical_list: D004272:DNA, Mitochondrial; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012313:RNA; D004317:Doxorubicin
keywords: PGC-1α; TT21C.; doxorubicin; mitochondrial toxicity; point of departure