Maintenance of mitochondrial genomic integrity in the absence of manganese superoxide dismutase in mouse liver hepatocytes.

TitleMaintenance of mitochondrial genomic integrity in the absence of manganese superoxide dismutase in mouse liver hepatocytes.
Publication TypeJournal Article
Year of Publication2013
AuthorsCyr AR, Brown KE, McCormick ML, Coleman MC, Case AJ, Watts GS, Futscher BW, Spitz DR, Domann FE
JournalRedox Biol
Volume1
Pagination172-7
Date Published2013
ISSN2213-2317
KeywordsAnimals, Cells, Cultured, DNA, Mitochondrial, Gene Knockout Techniques, Hepatocytes, High-Throughput Nucleotide Sequencing, Mice, Mice, Inbred C57BL, Mitochondria, Mutation, Organ Specificity, Sequence Analysis, DNA, Superoxide Dismutase, Transcription, Genetic
Abstract

Manganese superoxide dismutase, encoded by the Sod2 gene, is a ubiquitously expressed mitochondrial antioxidant enzyme that is essential for mammalian life. Mice born with constitutive genetic knockout of Sod2 do not survive the neonatal stage, which renders the longitudinal study of the biochemical and metabolic effects of Sod2 loss difficult. However, multiple studies have demonstrated that tissue-specific knockout of Sod2 in murine liver yields no observable gross pathology or injury to the mouse. We hypothesized that Sod2 loss may have sub-pathologic effects on liver biology, including the acquisition of reactive oxygen species-mediated mitochondrial DNA mutations. To evaluate this, we established and verified a hepatocyte-specific knockout of Sod2 in C57/B6 mice using Cre-LoxP recombination technology. We utilized deep sequencing to identify possible mutations in Sod2 (-/-) mitochondrial DNA as compared to wt, and both RT-PCR and traditional biochemical assays to evaluate baseline differences in redox-sensitive pathways in Sod2 (-/-) hepatocytes. Surprisingly, no mutations in Sod2 (-/-) mitochondrial DNA were detected despite measurable increases in dihydroethidium staining in situ and concomitant decreases in complex II activity indicative of elevated superoxide in the Sod2 (-/-) hepatocytes. In contrast, numerous compensatory alterations in gene expression were identified that suggest hepatocytes have a remarkable capacity to adapt and overcome the loss of Sod2 through transcriptional means. Taken together, these results suggest that murine hepatocytes have a large reserve capacity to cope with the presence of additional mitochondrial reactive oxygen species.

DOI10.1016/j.redox.2013.01.001
Alternate JournalRedox Biol
PubMed ID24024150
PubMed Central IDPMC3757676
Grant ListP30 CA023074 / CA / NCI NIH HHS / United States
P30 ES005605 / ES / NIEHS NIH HHS / United States
R01CA115438 / CA / NCI NIH HHS / United States
P30 ES006694 / ES / NIEHS NIH HHS / United States
R01 CA133114 / CA / NCI NIH HHS / United States
P30 CA086862 / CA / NCI NIH HHS / United States
R01 CA115438 / CA / NCI NIH HHS / United States
P30CA086862 / CA / NCI NIH HHS / United States
P42ES004940 / ES / NIEHS NIH HHS / United States
T32 CA078586 / CA / NCI NIH HHS / United States
P42 ES004940 / ES / NIEHS NIH HHS / United States
T32 GM007337 / GM / NIGMS NIH HHS / United States
Faculty Member Reference: 
George Watts, Ph.D.