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

• Published in: Journal of the American Heart Association Vol. 1; no. 6; pp. e003855 - n/a
• Main Authors: Wan, Xianxiu, Gupta, Shivali, Zago, Maria P., Davidson, Mercy M., Dousset, Pierre, Amoroso, Alejandro, Garg, Nisha Jain
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.12.2012
• Subjects: Blotting, Western; Cells, Cultured; Chagas disease; Chagas Disease - genetics; Chagas Disease - metabolism; Chagas Disease - physiopathology; DNA Replication - physiology; DNA, Mitochondrial - metabolism; DNA, Mitochondrial - physiology; Gene Expression Regulation; Humans; Immunohistochemistry; Microscopy, Fluorescence; mitochondrial biogenesis; Mitochondrial Diseases - genetics; Mitochondrial Diseases - physiopathology; Mitochondrial Turnover - physiology; mtDNA replication; Myocytes, Cardiac - physiology; Myocytes, Cardiac - ultrastructure; NF-E2-Related Factor 2 - genetics; NF-E2-Related Factor 2 - metabolism; NF-E2-Related Factor 2 - physiology; NRF2; Nuclear Respiratory Factor 1 - genetics; Nuclear Respiratory Factor 1 - metabolism; Nuclear Respiratory Factor 1 - physiology; Original Research; oxidative stress; PGC‐1α; Reactive Oxygen Species - metabolism; Real-Time Polymerase Chain Reaction; RNA, Messenger - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription Factors - physiology; Trypanosoma cruzi; mtDNA replication; NRF2; Chagas disease; PGC-1α; mitochondrial biogenesis; oxidative stress; Trypanosoma cruzi
• ISSN: 2047-9980; 2047-9980
• DOI: 10.1161/JAHA.112.003855

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. Methods and 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.