title: Defects of mtDNA replication impaired mitochondrial biogenesis during Trypanosoma cruzi infection in human cardiomyocytes and chagasic patients: the role of Nrf1/2 and antioxidant response.
abstract: BACKGROUND
  Mitochondrial dysfunction is a key determinant in chagasic cardiomyopathy development in mice; however, its relevance in human Chagas disease is not known. We determined if defects in mitochondrial biogenesis and dysregulation of peroxisome proliferator-activated receptor gamma (PPARγ) coactivator-1 (PGC-1)-regulated transcriptional pathways constitute a mechanism or mechanisms underlying mitochondrial oxidative-phosphorylation (OXPHOS) deficiency in human Chagas disease.
  
  
  RESULTS
  We utilized human cardiomyocytes and left-ventricular tissue from chagasic and other cardiomyopathy patients and healthy donors (n>6/group). We noted no change in citrate synthase activity, yet mRNA and/or protein levels of subunits of the respiratory complexes were significantly decreased in Trypanosoma cruzi-infected cardiomyocytes (0 to 24 hours) and chagasic hearts. We observed increased mRNA and decreased nuclear localization of PGC-1-coactivated transcription factors, yet the expression of genes for PPARγ-regulated fatty acid oxidation and nuclear respiratory factor (NRF1/2)-regulated mtDNA replication and transcription machinery was enhanced in infected cardiomyocytes and chagasic hearts. The D-loop formation was normal or higher, but mtDNA replication and mtDNA content were decreased by 83% and 40% to 65%, respectively. Subsequently, we noted that reactive oxygen species (ROS), oxidative stress, and mtDNA oxidation were significantly increased, yet NRF1/2-regulated antioxidant gene expression remained compromised in infected cardiomyocytes and chagasic hearts.
  
  
  CONCLUSIONS
  The replication of mtDNA was severely compromised, resulting in a significant loss of mtDNA and expression of OXPHOS genes in T cruzi-infected cardiomyocytes and chagasic hearts. Our data suggest increased ROS generation and selective functional incapacity of NRF2-mediated antioxidant gene expression played a role in the defects in mtDNA replication and unfitness of mtDNA for replication and gene expression in Chagas disease.
authors: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-1070, USA.
authors: Xianxiu
authors: X
authors: Wan
authors: Shivali
authors: S
authors: Gupta
authors: Maria P
authors: MP
authors: Zago
authors: Mercy M
authors: MM
authors: Davidson
authors: Pierre
authors: P
authors: Dousset
authors: Alejandro
authors: A
authors: Amoroso
authors: Nisha Jain
authors: NJ
authors: Garg
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D014355:Chagas Disease / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D004261:DNA Replication / Q000502:physiology*; D004272:DNA, Mitochondrial / Q000378:metabolism / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D028361:Mitochondrial Diseases / Q000235:genetics / Q000503:physiopathology; D063269:Mitochondrial Turnover / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology / Q000648:ultrastructure; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051266:Nuclear Respiratory Factor 1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D014349:Trypanosoma cruzi
chemical_list: D004272:DNA, Mitochondrial; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C495633:NRF1 protein, human; D051266:Nuclear Respiratory Factor 1; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014157:Transcription Factors; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1
keywords: Chagas disease; NRF2; PGC-1α; Trypanosoma cruzi; mitochondrial biogenesis; mtDNA replication; oxidative stress