BackgroundDiets high in saturated fat and sugar, termed ‘western diets’, have been associated wit... more BackgroundDiets high in saturated fat and sugar, termed ‘western diets’, have been associated with several negative health outcomes, including increased risk for neurodegenerative disease. Parkinson’s Disease (PD) is the second most prevalent neurodegenerative disease and is characterized by the progressive death of dopaminergic neurons in the brain. We build upon previous work characterizing the impact of high sugar diets inCaenorhabditis elegansto mechanistically evaluate the relationship between high sugar diets and dopaminergic neurodegeneration.ResultsAdult high glucose and fructose diets, or exposure from day 1-5 of adulthood, led to increased lipid content and shorter lifespan and decreased reproduction. However, in contrast to previous reports, we found that adult chronic high-glucose and high-fructose diets did not induce dopaminergic neurodegeneration alone and were protective from 6-hydroxydopamine (6-OHDA) induced degeneration. Neither sugar altered baseline electron tra...
Exercise can protect against cardiovascular disease, neurodegenerative disease, diabetes, cancer,... more Exercise can protect against cardiovascular disease, neurodegenerative disease, diabetes, cancer, and age-associated declines in muscle, immune, and cognitive function. In fact, regular physical exercise is the most powerful intervention known to enhance robustness of health and aging. Still, the molecular and cellular mechanisms that mediate system-wide exercise benefits remain poorly understood, especially as applies to “off target” tissues that do not participate directly in training activity. Elaborating molecular mechanisms of whole-animal exercise benefits is therefore of considerable importance to human health. The development of exercise protocols for short-lived genetic models holds great potential for deciphering fundamental mechanisms of exercise trans-tissue signaling during the entire aging process. Here, we report on the optimization of a long-term swim exercise protocol for C. elegans and we demonstrate its benefits to diverse aging tissues, even if exercise occurs on...
Mitochondria are central players in host immunometabolism as they function not only as metabolic ... more Mitochondria are central players in host immunometabolism as they function not only as metabolic hubs but also as signaling platforms regulating innate immunity. Environmental exposures to mitochondrial toxicants occur widely and are increasingly frequent. Exposures to these mitotoxicants may pose a serious threat to organismal health and the onset of diseases by disrupting immunometabolic pathways. In this study, we investigated whether the Complex I inhibitor rotenone could alter C. elegans immunometabolism and disease susceptibility. C. elegans embryos were exposed to rotenone (0.5 µM) or DMSO (0.125%) until they reached the L4 larval stage. Inhibition of mitochondrial respiration by rotenone and disruption of mitochondrial metabolism were evidenced by rotenone-induced detrimental effects on mitochondrial efficiency and nematode growth and development. Next, through transcriptomic analysis, we investigated if this specific but mild mitochondrial stress that we detected would lead...
Mitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet the proce... more Mitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet the processes that regulate the accumulation of de novo mtDNA mutations and modulate mtDNA heteroplasmy are not fully elucidated. Mitochondria lack certain DNA repair processes, which could contribute to polymerase error-induced mutations and increase susceptibility to chemical-induced mtDNA mutagenesis. We conducted error-corrected, ultra-sensitive Duplex Sequencing to investigate the effects of two known nuclear genome mutagens, cadmium and Aflatoxin B1, on germline mtDNA mutagenesis in Caenorhabditis elegans. Detection of thousands of mtDNA mutations revealed pervasive heteroplasmy in C. elegans and that mtDNA mutagenesis is dominated by C:G → A:T mutations generally attributed to oxidative damage. However, there was no effect of either exposure on mtDNA mutation frequency, spectrum, or trinucleotide context signature despite a significant increase in nuclear mutation rate after aflatoxin B1 e...
ABSTRACTMitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet t... more ABSTRACTMitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet the processes that regulate the accumulation of de novo mtDNA mutations and modulate mtDNA heteroplasmy are not fully elucidated. Mitochondria lack certain DNA repair processes, which could contribute to polymerase error-induced mutations and increase susceptibility to chemical-induced mtDNA mutagenesis. We conducted error-corrected, ultra-sensitive Duplex Sequencing to investigate the effects of two known nuclear genome mutagens, cadmium and Aflatoxin B1, on germline mtDNA mutagenesis in Caenorhabditis elegans. After 1,750 generations, we detected 2,270 single nucleotide mutations. Heteroplasmy is pervasive in C. elegans and mtDNA mutagenesis is dominated by C:G → A:T mutations generally attributed to oxidative damage, yet there was no effect of either exposure on mtDNA mutation frequency, spectrum, or trinucleotide context signature. Mitophagy may play a role in eliminating mtDNA damage...
The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mt... more The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mtDNA is more susceptible to damage than nuclear DNA (nucDNA), and many environmental toxicants target the mitochondria. Reports from the toxicological literature suggest that exposure to early-life mitochondrial damage could lead to deleterious consequences later in life (the “Developmental Origins of Health and Disease” paradigm) but reports from other fields often report beneficial (“mitohormetic”) responses to such damage. Here, we test the effects of low (causing no change in lifespan) levels of ultraviolet C (UVC)-induced, irreparable mtDNA damage during early development inCaenorhabditis elegans. This exposure led to life-long reductions in mtDNA copy number and steady-state ATP levels, accompanied by increased oxygen consumption and altered metabolite profiles, suggesting inefficient mitochondrial function. Exposed nematodes were also developmentally delayed, reached smaller adult ...
Complex I deficiency represents the most frequent pathogenetic cause of human mitochondriopathies... more Complex I deficiency represents the most frequent pathogenetic cause of human mitochondriopathies. Therapeutic options for these neurodevelopmental life-threating disorders do not exist, partly due to the scarcity of appropriate model systems to study them. Caenorhabditis elegans is a genetically tractable model organism widely used to investigate neuronal pathologies. Here, we generated new C. elegans models for mitochondriopathies and showed that depletion of Complex I subunits recapitulates biochemical, cellular and neurodevelopmental aspects of the human diseases. Two models, nuo-5/NDUFS1- and lpd-5/NDUFS4-depleted animals, were exploited for a suppressor screening that identified lutein for its ability to rescue animals’ neurodevelopmental deficits. We uncovered overexpression of synaptic neuroligins as an evolutionarily conserved consequence of mitochondrial dysfunction, which we found to mediate an early cholinergic defect in C. elegans. We showed lutein exerts its beneficial...
BackgroundDiets high in saturated fat and sugar, termed ‘western diets’, have been associated wit... more BackgroundDiets high in saturated fat and sugar, termed ‘western diets’, have been associated with several negative health outcomes, including increased risk for neurodegenerative disease. Parkinson’s Disease (PD) is the second most prevalent neurodegenerative disease and is characterized by the progressive death of dopaminergic neurons in the brain. We build upon previous work characterizing the impact of high sugar diets inCaenorhabditis elegansto mechanistically evaluate the relationship between high sugar diets and dopaminergic neurodegeneration.ResultsAdult high glucose and fructose diets, or exposure from day 1-5 of adulthood, led to increased lipid content and shorter lifespan and decreased reproduction. However, in contrast to previous reports, we found that adult chronic high-glucose and high-fructose diets did not induce dopaminergic neurodegeneration alone and were protective from 6-hydroxydopamine (6-OHDA) induced degeneration. Neither sugar altered baseline electron tra...
Exercise can protect against cardiovascular disease, neurodegenerative disease, diabetes, cancer,... more Exercise can protect against cardiovascular disease, neurodegenerative disease, diabetes, cancer, and age-associated declines in muscle, immune, and cognitive function. In fact, regular physical exercise is the most powerful intervention known to enhance robustness of health and aging. Still, the molecular and cellular mechanisms that mediate system-wide exercise benefits remain poorly understood, especially as applies to “off target” tissues that do not participate directly in training activity. Elaborating molecular mechanisms of whole-animal exercise benefits is therefore of considerable importance to human health. The development of exercise protocols for short-lived genetic models holds great potential for deciphering fundamental mechanisms of exercise trans-tissue signaling during the entire aging process. Here, we report on the optimization of a long-term swim exercise protocol for C. elegans and we demonstrate its benefits to diverse aging tissues, even if exercise occurs on...
Mitochondria are central players in host immunometabolism as they function not only as metabolic ... more Mitochondria are central players in host immunometabolism as they function not only as metabolic hubs but also as signaling platforms regulating innate immunity. Environmental exposures to mitochondrial toxicants occur widely and are increasingly frequent. Exposures to these mitotoxicants may pose a serious threat to organismal health and the onset of diseases by disrupting immunometabolic pathways. In this study, we investigated whether the Complex I inhibitor rotenone could alter C. elegans immunometabolism and disease susceptibility. C. elegans embryos were exposed to rotenone (0.5 µM) or DMSO (0.125%) until they reached the L4 larval stage. Inhibition of mitochondrial respiration by rotenone and disruption of mitochondrial metabolism were evidenced by rotenone-induced detrimental effects on mitochondrial efficiency and nematode growth and development. Next, through transcriptomic analysis, we investigated if this specific but mild mitochondrial stress that we detected would lead...
Mitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet the proce... more Mitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet the processes that regulate the accumulation of de novo mtDNA mutations and modulate mtDNA heteroplasmy are not fully elucidated. Mitochondria lack certain DNA repair processes, which could contribute to polymerase error-induced mutations and increase susceptibility to chemical-induced mtDNA mutagenesis. We conducted error-corrected, ultra-sensitive Duplex Sequencing to investigate the effects of two known nuclear genome mutagens, cadmium and Aflatoxin B1, on germline mtDNA mutagenesis in Caenorhabditis elegans. Detection of thousands of mtDNA mutations revealed pervasive heteroplasmy in C. elegans and that mtDNA mutagenesis is dominated by C:G → A:T mutations generally attributed to oxidative damage. However, there was no effect of either exposure on mtDNA mutation frequency, spectrum, or trinucleotide context signature despite a significant increase in nuclear mutation rate after aflatoxin B1 e...
ABSTRACTMitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet t... more ABSTRACTMitochondrial DNA (mtDNA) is prone to mutation in aging and over evolutionary time, yet the processes that regulate the accumulation of de novo mtDNA mutations and modulate mtDNA heteroplasmy are not fully elucidated. Mitochondria lack certain DNA repair processes, which could contribute to polymerase error-induced mutations and increase susceptibility to chemical-induced mtDNA mutagenesis. We conducted error-corrected, ultra-sensitive Duplex Sequencing to investigate the effects of two known nuclear genome mutagens, cadmium and Aflatoxin B1, on germline mtDNA mutagenesis in Caenorhabditis elegans. After 1,750 generations, we detected 2,270 single nucleotide mutations. Heteroplasmy is pervasive in C. elegans and mtDNA mutagenesis is dominated by C:G → A:T mutations generally attributed to oxidative damage, yet there was no effect of either exposure on mtDNA mutation frequency, spectrum, or trinucleotide context signature. Mitophagy may play a role in eliminating mtDNA damage...
The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mt... more The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mtDNA is more susceptible to damage than nuclear DNA (nucDNA), and many environmental toxicants target the mitochondria. Reports from the toxicological literature suggest that exposure to early-life mitochondrial damage could lead to deleterious consequences later in life (the “Developmental Origins of Health and Disease” paradigm) but reports from other fields often report beneficial (“mitohormetic”) responses to such damage. Here, we test the effects of low (causing no change in lifespan) levels of ultraviolet C (UVC)-induced, irreparable mtDNA damage during early development inCaenorhabditis elegans. This exposure led to life-long reductions in mtDNA copy number and steady-state ATP levels, accompanied by increased oxygen consumption and altered metabolite profiles, suggesting inefficient mitochondrial function. Exposed nematodes were also developmentally delayed, reached smaller adult ...
Complex I deficiency represents the most frequent pathogenetic cause of human mitochondriopathies... more Complex I deficiency represents the most frequent pathogenetic cause of human mitochondriopathies. Therapeutic options for these neurodevelopmental life-threating disorders do not exist, partly due to the scarcity of appropriate model systems to study them. Caenorhabditis elegans is a genetically tractable model organism widely used to investigate neuronal pathologies. Here, we generated new C. elegans models for mitochondriopathies and showed that depletion of Complex I subunits recapitulates biochemical, cellular and neurodevelopmental aspects of the human diseases. Two models, nuo-5/NDUFS1- and lpd-5/NDUFS4-depleted animals, were exploited for a suppressor screening that identified lutein for its ability to rescue animals’ neurodevelopmental deficits. We uncovered overexpression of synaptic neuroligins as an evolutionarily conserved consequence of mitochondrial dysfunction, which we found to mediate an early cholinergic defect in C. elegans. We showed lutein exerts its beneficial...
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Papers by Joel Meyer