Inhibition of ATR Reverses a Mitochondrial Respiratory Insufficiency.

Diseases that affect the mitochondrial electron transport chain (ETC) often manifest as threshold effect disorders, meaning patients only become symptomatic once a certain level of ETC dysfunction is reached. Cells can invoke mechanisms to circumvent reaching their critical ETC threshold, but it is an ongoing challenge to identify such processes. In the nematode , severe reduction of mitochondrial ETC activity shortens life, but mild reduction actually extends it, providing an opportunity to identify threshold circumvention mechanisms.

BRCA1 and BARD1 mediate apoptotic resistance but not longevity upon mitochondrial stress in .

Interventions that promote healthy aging are typically associated with increased stress resistance. Paradoxically, reducing the activity of core biological processes such as mitochondrial or insulin metabolism promotes the expression of adaptive responses, which in turn increase animal longevity and resistance to stress. In this study, we investigated the relation between the extended lifespan elicited by reduction in mitochondrial functionality and resistance to genotoxic stress.

CLD1 Reverses the Ubiquinone Insufficiency of Mutant cat5/coq7 in a Saccharomyces cerevisiae Model System.

Ubiquinone (Qn) functions as a mobile electron carrier in mitochondria. In humans, Q biosynthetic pathway mutations lead to Q10 deficiency, a life threatening disorder. We have used a Saccharomyces cerevisiae model of Q6 deficiency to screen for new modulators of ubiquinone biosynthesis.

DLK-1, SEK-3 and PMK-3 Are Required for the Life Extension Induced by Mitochondrial Bioenergetic Disruption in C. elegans.

Mitochondrial dysfunction underlies numerous age-related pathologies. In an effort to uncover how the detrimental effects of mitochondrial dysfunction might be alleviated, we examined how the nematode C. elegans not only adapts to disruption of the mitochondrial electron transport chain, but in many instances responds with extended lifespan.

Mitochondrial metabolites extend lifespan.

Disruption of mitochondrial respiration in the nematode Caenorhabditis elegans can extend lifespan. We previously showed that long-lived respiratory mutants generate elevated amounts of α-ketoacids. These compounds are structurally related to α-ketoglutarate, suggesting they may be biologically relevant.

The role of mitochondrial dysfunction in age-related diseases.

The aging process is accompanied by the onset of disease and a general decline in wellness. Insights into the aging process have revealed a number of cellular hallmarks of aging, among these epigenetic alterations, loss of proteostasis, mitochondrial dysfunction, cellular senescence, and stem cell exhaustion. Mitochondrial dysfunction increasingly appears to be a common factor connecting several of these hallmarks, driving the aging process and afflicting tissues throughout the body.

L-2-Hydroxyglutarate: an epigenetic modifier and putative oncometabolite in renal cancer.

Unlabelled: Through unbiased metabolomics, we identified elevations of the metabolite 2-hydroxyglutarate (2HG) in renal cell carcinoma (RCC). 2HG can inhibit 2-oxoglutaratre (2-OG)-dependent dioxygenases that mediate epigenetic events, including DNA and histone demethylation. 2HG accumulation, specifically the d enantiomer, can result from gain-of-function mutations of isocitrate dehydrogenase (IDH1, IDH2) found in several different tumors.

The paradox of mitochondrial dysfunction and extended longevity.

Mitochondria play numerous, essential roles in the life of eukaryotes. Disruption of mitochondrial function in humans is often pathological or even lethal. Surprisingly, in some organisms mitochondrial dysfunction can result in life extension.

TAF-4 is required for the life extension of isp-1, clk-1 and tpk-1 Mit mutants.

While numerous life-extending manipulations have been discovered in the nematode Caenorhabditis elegans, one that remains most enigmatic is disruption of oxidative phosphorylation. In order to unravel how such an ostensibly deleterious manipulation can extend lifespan, we sought to identify the ensemble of nuclear transcription factors that are activated in response to defective mitochondrial electron transport chain (ETC) function. Using a feeding RNAi approach, we targeted over 400 transcription factors and identified 15 that, when reduced in function, reproducibly and differentially altered the development, stress response, and/or fecundity of isp-1(qm150) Mit mutants relative to wild-type animals.

Exometabolomic mapping of Caenorhabditis elegans: a tool to noninvasively investigate aging.

Metabolomic analyses can provide valuable information about the internal metabolism of an organism; however, these studies can become quickly complicated by the large number of metabolites that are often detected. Overcoming this limitation requires high-resolution analytical separation techniques, coupled with high-power deconvolution software. Additionally, much care must be taken in metabolomic sample preparation to quench active enzymes and avoid artifactual changes in the metabolome.

Autophagy induction extends lifespan and reduces lipid content in response to frataxin silencing in C. elegans.

Severe mitochondria deficiency leads to a number of devastating degenerative disorders, yet, mild mitochondrial dysfunction in different species, including the nematode Caenorhabditis elegans, can have pro-longevity effects. This apparent paradox indicates that cellular adaptation to partial mitochondrial stress can induce beneficial responses, but how this is achieved is largely unknown. Complete absence of frataxin, the mitochondrial protein defective in patients with Friedreich's ataxia, is lethal in C.

A metabolic signature for long life in the Caenorhabditis elegans Mit mutants.

Mit mutations that disrupt function of the mitochondrial electron transport chain can, inexplicably, prolong Caenorhabditis elegans lifespan. In this study we use a metabolomics approach to identify an ensemble of mitochondrial-derived α-ketoacids and α-hydroxyacids that are produced by long-lived Mit mutants but not by other long-lived mutants or by short-lived mitochondrial mutants. We show that accumulation of these compounds is dependent on concerted inhibition of three α-ketoacid dehydrogenases that share dihydrolipoamide dehydrogenase (DLD) as a common subunit, a protein previously linked in humans with increased risk of Alzheimer's disease.

Profiling the anaerobic response of C. elegans using GC-MS.

The nematode Caenorhabditis elegans is a model organism that has seen extensive use over the last four decades in multiple areas of investigation. In this study we explore the response of the nematode Caenorhabditis elegans to acute anoxia using gas-chromatography mass-spectrometry (GC-MS). We focus on the readily-accessible worm exometabolome to show that C.

The role of MAP4K3 in lifespan regulation of Caenorhabditis elegans.

The TOR pathway is a kinase signaling pathway that regulates cellular growth and proliferation in response to nutrients and growth factors. TOR signaling is also important in lifespan regulation - when this pathway is inhibited, either naturally, by genetic mutation, or by pharmacological means, lifespan is extended. MAP4K3 is a Ser/Thr kinase that has recently been found to be involved in TOR activation.

Applications of mass spectrometry to metabolomics and metabonomics: detection of biomarkers of aging and of age-related diseases.

Every 5 years or so new technologies, or new combinations of old ones, seemingly burst onto the science scene and are then sought after until they reach the point of becoming commonplace. Advances in mass spectrometry instrumentation, coupled with the establishment of standardized chemical fragmentation libraries, increased computing power, novel data-analysis algorithms, new scientific applications, and commercial prospects have made mass spectrometry-based metabolomics the latest sought-after technology. This methodology affords the ability to dynamically catalogue and quantify, in parallel, femtomole quantities of cellular metabolites.

Breaking Caenorhabditis elegans the easy way using the Balch homogenizer: an old tool for a new application.

The nematode Caenorhabditis elegans is a model organism best known for its powerful genetics. There is an increasing need in the worm community to couple genetics with biochemistry. Isolation of functionally active proteins or nucleic acids without the use of strong oxidizing denaturants or of subcellular compartments from C.

Bacteria, yeast, worms, and flies: exploiting simple model organisms to investigate human mitochondrial diseases.

The extensive conservation of mitochondrial structure, composition, and function across evolution offers a unique opportunity to expand our understanding of human mitochondrial biology and disease. By investigating the biology of much simpler model organisms, it is often possible to answer questions that are unreachable at the clinical level. Here, we review the relative utility of four different model organisms, namely the bacterium Escherichia coli, the yeast Saccharomyces cerevisiae, the nematode Caenorhabditis elegans, and the fruit fly Drosophila melanogaster, in studying the role of mitochondrial proteins relevant to human disease.

Long-lived mitochondrial (Mit) mutants of Caenorhabditis elegans utilize a novel metabolism.

The Caenorhabditis elegans mitochondrial (Mit) mutants have disrupted mitochondrial electron transport chain (ETC) functionality, yet, surprisingly, they are long lived. We have previously proposed that Mit mutants supplement their energy needs by exploiting alternate energy production pathways normally used by wild-type animals only when exposed to hypoxic conditions. We have also proposed that longevity in the Mit mutants arises as a property of their new metabolic state.

Mortality shifts in Caenorhabditis elegans: remembrance of conditions past.

The analysis of age-specific mortality can yield insights into how anti-aging interventions operate that cannot be matched by simple assessment of longevity. Mortality, as opposed to longevity, can be used to assess the effects of an anti-aging intervention on a daily basis, rather than only after most animals have died. Various gerontogene mutations in Caenorhabditis elegans have been shown to increase longevity as much as tenfold and to decrease mortality at some ages even more.

p53/CEP-1 increases or decreases lifespan, depending on level of mitochondrial bioenergetic stress.

Mitochondrial pathologies underlie a number of life-shortening diseases in humans. In the nematode Caenorhabditis elegans, severely reduced expression of mitochondrial proteins involved in electron transport chain-mediated energy production also leads to pathological phenotypes, including arrested development and/or shorter life; in sharp contrast, mild suppression of these same proteins extends lifespan. In this study, we show that the C.

Relationship between mitochondrial electron transport chain dysfunction, development, and life extension in Caenorhabditis elegans.

Prior studies have shown that disruption of mitochondrial electron transport chain (ETC) function in the nematode Caenorhabditis elegans can result in life extension. Counter to these findings, many mutations that disrupt ETC function in humans are known to be pathologically life-shortening. In this study, we have undertaken the first formal investigation of the role of partial mitochondrial ETC inhibition and its contribution to the life-extension phenotype of C.

Proteasomal dysfunction activates the transcription factor SKN-1 and produces a selective oxidative-stress response in Caenorhabditis elegans.

SKN-1 in the nematode worm Caenorhabditis elegans is functionally orthologous to mammalian NRF2 [NF-E2 (nuclear factor-E2)-related factor 2], a protein regulating response to oxidative stress. We have examined both the expression and activity of SKN-1 in response to a variety of oxidative stressors and to down-regulation of specific gene targets by RNAi (RNA interference). We used an SKN-1-GFP (green fluorescent protein) translational fusion to record changes in both skn-1 expression and SKN-1 nuclear localization, and a gst-4-GFP transcriptional fusion to measure SKN-1 transcriptional activity.

Caenorhabditis elegans mitochondrial mutants as an investigative tool to study human neurodegenerative diseases associated with mitochondrial dysfunction.

In humans, well over one hundred diseases have been linked to mitochondrial dysfunction and many of these are associated with neurodegeneration. At the root of most of these diseases lay ineffectual energy production, caused either by direct or indirect disruption to components of the mitochondrial electron transport chain. It is surprising then to learn that, in the nematode Caenorhabditis elegans, a collection of mutants which share disruptions in some of the same genes that cause mitochondrial pathogenesis in humans are in fact long-lived.

Long-lived C. elegans mitochondrial mutants as a model for human mitochondrial-associated diseases.

Mitochondria play a pivotal role in the life of cells, controlling diverse processes ranging from energy production to the regulation of cell death. In humans, numerous pathological conditions have been linked to mitochondrial dysfunction. Cancer, diabetes, obesity, neurodegeneration, cardiomyopathy and even aging are all associated with mitochondrial dysfunction.