In order to increase understanding of the molecular basis of aging, we have generated a mouse model (PolgD257A) that should display increased spontaneous mutation rates in mitochondrial DNA (mtDNA). This animal model was generated by introducing a specific mutation in the exonuclease domain of mouse DNA Polymerase Gamma (POLG) in ES cells. Mice carrying a """"""""mutator"""""""" phenotype in mtDNA will allow investigators to elucidate one of the central unresolved issues in aging research, the contribution of mitochondrial mutations to the aging process. The central hypothesis to be tested is that mutations in mtDNA, known to be associated with aging in many postmitotic tissues, play a causal role in the aging process.
Specific Aim 1. Characterization of skeletal muscle in mitochondrial mutator mice. Mice carrying the PolgD257A mutation are viable and display no obvious developmental defects. We propose to determine the mutational spectrum in mtDNA of these animals in order to estimate mutational frequency in vivo. We also propose to determine the level of electron transport system (ETS) abnormalities, as determined by loss of cytochrome c oxidase (COX) activity along individual muscle fibers of 5-month, 15-month and 30-month PolgD257A and wild-type control animals. Isolated mitochondria will also be characterized for age-related biochemical abnormalities, including alterations in metabolic potential and OS markers.
Specific Aim 2. Gene expression profiling in skeletal muscle. We propose to characterize the gene expression profile of skeletal muscle of PolgD257A mice over the adult lifespan in order to determine if mitochondrial mutations accelerate the aging process at the molecular level. Specifically, mice will be studied at 5 months, 15 months and 30 months of age. These experiments will involve both wild-type and PolgD257A mice and utilize high density oligonucleotide arrays, which provide data on over 12,000 genes and ESTs.
Specific Aim 3. Survival and Disease Patterns in PolgD257A Mice. We propose to determine the survival and disease patterns of PolgD257A mice. Animals will be backcrossed to the B6 (C57BL/6 mice) genetic background, which our laboratory has extensively characterized for disease patterns and mortality. Survival patterns, including survival curves and calculation of mortality rates, will be performed for PolgD257A mice and wild-type controls. Animals will be observed for the development of neoplastic, neurologic and cardiac phenotypes and characterized at the histopathology level accordingly.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
1R01AG021905-01
Application #
6594804
Study Section
Geriatrics and Rehabilitation Medicine (GRM)
Program Officer
Finkelstein, David B
Project Start
2003-05-01
Project End
2008-04-30
Budget Start
2003-05-01
Budget End
2004-04-30
Support Year
1
Fiscal Year
2003
Total Cost
$381,273
Indirect Cost
Name
University of Wisconsin Madison
Department
Genetics
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Someya, Shinichi; Kujoth, Gregory C; Kim, Mi-Jung et al. (2017) Effects of calorie restriction on the lifespan and healthspan of POLG mitochondrial mutator mice. PLoS One 12:e0171159
Han, Chul; Linser, Paul; Park, Hyo-Jin et al. (2016) Sirt1 deficiency protects cochlear cells and delays the early onset of age-related hearing loss in C57BL/6 mice. Neurobiol Aging 43:58-71
Someya, Shinichi; Yu, Wei; Hallows, William C et al. (2010) Sirt3 mediates reduction of oxidative damage and prevention of age-related hearing loss under caloric restriction. Cell 143:802-12
Someya, Shinichi; Prolla, Tomas A (2010) Mitochondrial oxidative damage and apoptosis in age-related hearing loss. Mech Ageing Dev 131:480-6
Hiona, Asimina; Sanz, Alberto; Kujoth, Gregory C et al. (2010) Mitochondrial DNA mutations induce mitochondrial dysfunction, apoptosis and sarcopenia in skeletal muscle of mitochondrial DNA mutator mice. PLoS One 5:e11468
Someya, Shinichi; Tanokura, Masaru; Weindruch, Richard et al. (2010) Effects of caloric restriction on age-related hearing loss in rodents and rhesus monkeys. Curr Aging Sci 3:20-5
Bailey, Laura J; Cluett, Tricia J; Reyes, Aurelio et al. (2009) Mice expressing an error-prone DNA polymerase in mitochondria display elevated replication pausing and chromosomal breakage at fragile sites of mitochondrial DNA. Nucleic Acids Res 37:2327-35
Someya, Shinichi; Xu, Jinze; Kondo, Kenji et al. (2009) Age-related hearing loss in C57BL/6J mice is mediated by Bak-dependent mitochondrial apoptosis. Proc Natl Acad Sci U S A 106:19432-7
Someya, Shinichi; Yamasoba, Tatsuya; Kujoth, Gregory C et al. (2008) The role of mtDNA mutations in the pathogenesis of age-related hearing loss in mice carrying a mutator DNA polymerase gamma. Neurobiol Aging 29:1080-92
Vermulst, Marc; Wanagat, Jonathan; Kujoth, Gregory C et al. (2008) DNA deletions and clonal mutations drive premature aging in mitochondrial mutator mice. Nat Genet 40:392-4

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