Mitochondrial function declines with age and is exacerbated in disease states such as Parkinson's. One potential cause of the mitochondrial decline is the propagation of deleterious mitochondrial genomes (mtDNAs) throughout an organism's lifetime as has been observed in individual muscle cells or dopaminergic neurons. mtDNAs only encode respiratory chain and ATP synthase components and thus lesions result in oxidative phosphorylation (OxPhos) deficiency. Because mtDNAs exist at 100s-1000s of copies per cell, a lesion in a single genome is well tolerated. However, if the deleterious genome accumulates to greater than ~60%, pathology related to OxPhos dysfunction ensues including cell degeneration and death. It is currently unclear how deleterious mtDNAs are maintained, how they are propagated and ultimately why they are toxic. One mechanism by which cells respond to OxPhos deficiency is by activating the mitochondrial unfolded protein response (UPRmt), which initiates a mitochondrial repair and recovery program. We have found that UPRmt activation provides protection against OxPhos deficiencies caused by nuclear mutations in OxPhos genes or against bacterial derived toxins (P. aeruginosa produces cyanide for example). Our surprising preliminary data indicate that the UPRmt is required to maintain and propagate deleterious mtDNAs in a C. elegans model of heteroplasmy. Therefore, we hypothesize that deleterious mtDNAs are selfish, or parasitic, and take advantage of an endogenous stress response program in place to repair and respond to mitochondrial dysfunction. Here, we plan to examine the consequences of UPRmt activation and deleterious mtDNA propagation as a contributor to age-associated mitochondrial dysfunction.

Public Health Relevance

Mitochondrial dysfunction contributes to the aging process and to age-associated diseases such as Parkinson's. A potential cause of mitochondrial dysfunction is the accumulation and propagation of deleterious mitochondrial genomes that impair multiple cellular functions related to metabolism and oxidative phosphorylation. Here, we aim to understand the role of a mitochondrial protective stress response in the maintenance and propagation of deleterious mitochondrial genomes with the ultimate goal of designing strategies to eliminate or reduce their accumulation in aging or diseased cells.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
2R01AG040061-06
Application #
9234890
Study Section
Cellular Mechanisms in Aging and Development Study Section (CMAD)
Program Officer
Fridell, Yih-Woei
Project Start
2016-09-30
Project End
2021-04-30
Budget Start
2016-09-30
Budget End
2017-04-30
Support Year
6
Fiscal Year
2016
Total Cost
$351,370
Indirect Cost
$146,370
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
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Fiorese, Christopher J; Schulz, Anna M; Lin, Yi-Fan et al. (2016) The Transcription Factor ATF5 Mediates a Mammalian Mitochondrial UPR. Curr Biol 26:2037-2043
Lamech, Lilian T; Haynes, Cole M (2015) The unpredictability of prolonged activation of stress response pathways. J Cell Biol 209:781-7
Pellegrino, Mark W; Haynes, Cole M (2015) Mitophagy and the mitochondrial unfolded protein response in neurodegeneration and bacterial infection. BMC Biol 13:22

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