Project description:Environmental factors, including pesticides, have been linked to autism and neurodegeneration risk using retrospective epidemiological studies. Here, we sought to prospectively identify chemicals that share transcriptomic signatures with neurological disorders by exposing mouse cortical neuron-enriched cultures to hundreds of chemicals commonly found in the environment and on food. We find that rotenone, a pesticide associated with Parkinsonâs disease risk, and certain fungicides, including pyraclostrobin, trifloxystrobin, famoxadone, and fenamidone, produce transcriptional changes in vitro that are similar to those seen in brain samples from humans with autism, advanced age and neurodegeneration (Alzheimerâs disease, Huntingtonâs disease). These chemicals stimulate free radical production and disrupt microtubules in neurons, effects that can be reduced by pretreating with a microtubule stabilizer, an antioxidant, or with sulforaphane. Our study provides an approach to prospectively identify environmental chemicals that transcriptionally mimic autism and other brain disorders. 405 total samples, consisting of 297 unique chemicals and vehicle controls.
Project description:Environmental factors, including pesticides, have been linked to autism and neurodegeneration risk using retrospective epidemiological studies. Here, we sought to prospectively identify chemicals that share transcriptomic signatures with neurological disorders by exposing mouse cortical neuron-enriched cultures to hundreds of chemicals commonly found in the environment and on food. We find that rotenone, a pesticide associated with Parkinson’s disease risk, and certain fungicides, including pyraclostrobin, trifloxystrobin, famoxadone, and fenamidone, produce transcriptional changes in vitro that are similar to those seen in brain samples from humans with autism, advanced age and neurodegeneration (Alzheimer’s disease, Huntington’s disease). These chemicals stimulate free radical production and disrupt microtubules in neurons, effects that can be reduced by pretreating with a microtubule stabilizer, an antioxidant, or with sulforaphane. Our study provides an approach to prospectively identify environmental chemicals that transcriptionally mimic autism and other brain disorders.
Project description:This SuperSeries is composed of the following subset Series: GSE24992: Drosophila brain microRNA expression with age: miRNA profiling GSE25007: Drosophila brain gene expression with age: mRNA profiling GSE25008: Drosophila brain gene expression between wildtype and miR-34 null flies Refer to individual Series. Aging is the most prominent risk factor for human neurodegenerative disease, but underlying mechanisms that connect two processes are less well characterized. With age, the brain undergoes functional decline and perhaps degeneration. Such decline may not just contribute to normal aging, but also enhance susceptibility to and progression of age-related neurodegenerative diseases. Therefore, defining intrinsic factors and pathways that underline the normal integrity of the adult nervous system may lead to insights that potentially link aging and neurodegeneration. Here, we report a highly conserved microRNA (miRNA), miR-34, as a modulator of aging and neurodegeneration. Using Drosophila, we show that fly miR-34 expression is brain-enriched and strikingly upregulated with age. Functional studies reveal that, whereas animals without miR-34 are normal as young adults, upon aging, they gradually show late-onset deficits characteristic of accelerated brain aging; these include a transcriptional signature of aged animals, coupled with rapid functional decline, loss of brain integrity, followed by a catastrophic decline in adult viability. Moreover, upregulation of miR-34 protects against neurodegeneration induced by pathogenic human polyglutamine (polyQ) disease protein. We next reveal a dramatic effect of miR-34 to silence the Eip74EF gene of steroid hormone pathways in the adult, which is crucial to maintain the normal aging. Collectively, these data define a miR-34-mediated mechanism that specifically affects long-term integrity of the adult nervous system. miR-34 function in Drosophila may thus present a link that functionally connects aging and neurodegeneration. Our studies implicate essential roles of miRNA- dependent pathways in maintenance of the adult brain, disease pathogenesis and healthy aging.
Project description:A progressive loss of protein homeostasis is characteristic of aging and a driver of neurodegeneration. To investigate this process quantitatively, we characterized proteome dynamics during brain aging in the short-lived vertebrate Nothobranchius furzeri combining transcriptomics and proteomics. We detected a progressive reduction in the correlation between protein and mRNA, mainly due to post-transcriptional mechanisms that account for over 40% of the age-regulated proteins. These changes cause a progressive loss of stoichiometry in several protein complexes, including ribosomes, which show impaired assembly / dis-assembly and are enriched in protein aggregates in old brains. Mechanistically, we show that reduction of proteasome activity is an early event during brain aging and is sufficient to induce proteomic signatures of aging and loss of stoichiometry in vivo. Using longitudinal transcriptomic data, we show that the magnitude of early life decline in proteasome levels is a major risk factor for mortality. Our work defines causative events in the aging process that can be targeted to prevent loss of protein homeostasis and delay the onset of age-related neurodegeneration.
Project description:A progressive loss of protein homeostasis is characteristic of aging and a driver of neurodegeneration. To investigate this process quantitatively, we characterized proteome dynamics during brain aging in the short-lived vertebrate Nothobranchius furzeri combining transcriptomics and proteomics. We detected a progressive reduction in the correlation between protein and mRNA mainly due to post-transcriptional mechanisms that account for over 40% of the age-regulated proteins. These changes cause a progressive loss of stoichiometry in several protein complexes, including ribosomes, which show impaired assembly and are enriched in protein aggregates in old brains. Mechanistically, we show that reduction of proteasome activity is an early event during brain aging and is sufficient to induce proteomic signatures of aging and loss of stoichiometry in vivo. Using longitudinal transcriptomic data, we show that the magnitude of early life decline in proteasome levels is the major risk factor for mortality. Our work defines causative events in the aging process that can be targeted to prevent loss of protein homeostasis and delay the onset of age-related neurodegeneration.
Project description:A progressive loss of protein homeostasis is characteristic of aging and a driver of neurodegeneration. To investigate this process quantitatively, we characterized proteome dynamics during brain aging in the short-lived vertebrate Nothobranchius furzeri combining transcriptomics and proteomics. We detected a progressive reduction in the correlation between protein and mRNA mainly due to post-transcriptional mechanisms that account for over 40% of the age-regulated proteins. These changes cause a progressive loss of stoichiometry in several protein complexes, including ribosomes, which show impaired assembly and are enriched in protein aggregates in old brains. Mechanistically, we show that reduction of proteasome activity is an early event during brain aging and is sufficient to induce proteomic signatures of aging and loss of stoichiometry in vivo. Using longitudinal transcriptomic data, we show that the magnitude of early life decline in proteasome levels is the major risk factor for mortality. Our work defines causative events in the aging process that can be targeted to prevent loss of protein homeostasis and delay the onset of age-related neurodegeneration.
Project description:A progressive loss of protein homeostasis is characteristic of aging and a driver of neurodegeneration. To investigate this process quantitatively, we characterized proteome dynamics during brain aging in the short-lived vertebrate Nothobranchius furzeri combining transcriptomics and proteomics. We detected a progressive reduction in the correlation between protein and mRNA, mainly due to post-transcriptional mechanisms that account for over 40% of the age-regulated proteins. These changes cause a progressive loss of stoichiometry in several protein complexes, including ribosomes, which show impaired assembly / dis-assembly and are enriched in protein aggregates in old brains. Mechanistically, we show that reduction of proteasome activity is an early event during brain aging and is sufficient to induce proteomic signatures of aging and loss of stoichiometry in vivo. Using longitudinal transcriptomic data, we show that the magnitude of early life decline in proteasome levels is a major risk factor for mortality. Our work defines causative events in the aging process that can be targeted to prevent loss of protein homeostasis and delay the onset of age-related neurodegeneration.
Project description:Aging is a risk factor for neurodegenerative disease, but precise mechanisms that influence this relationship are still under investigation. Work in Drosophila melanogaster identified the microRNA miR-34 as a modifier of aging and neurodegeneration in the brain. MiR-34 mutants present aspects of early aging, including reduced lifespan, neurodegeneration, and a buildup of the repressive histone mark H3K27me3. To better understand how miR-34 regulated pathways contribute to age-associated phenotypes in the brain, here we transcriptionally profiled the miR-34 mutant brain. This identified that genes associated with translation are dysregulated in the miR-34 mutant. The brains of these animals show increased translation activity, accumulation of protein aggregation markers, and altered autophagy activity. To determine if altered H3K27me3 was responsible for this proteostasis dysregulation, we studied the effects of increased H3K27me3 by mutating the histone demethylase Utx. Reduced Utx activity enhanced neurodegeneration and mimicked the protein accumulation seen in miR-34 mutant brains. However, unlike the miR-34 mutant, Utx mutant brains did not show similar altered autophagy or translation activity, suggesting that additional miR-34-targeted pathways are involved. Transcriptional analysis of predicted miR-34 targets identified Lst8, a subunit of Tor Complex 1 (TORC1), as a potential target. We confirmed that miR-34 regulates the 3’ UTR of Lst8. Biological analysis of miR-34 mutant brains demonstrate that 4E-BP is hyperphosphorylated, consistent with increased Lst8 activity and changes in translation. Together, these results present novel understanding of brain aging and the role of the conserved miRNA miR-34 in impacting proteostasis in the brain with age.
Project description:Infantile neuronal ceroid lipofuscinosis (aka infantile Batten disease) is a severe neurodegenerative disorder of early childhood characterized by cortical atrophy, blindness and seizures, leading to premature death in the first decade. The disorder is caused by deficiency in a soluble lysosomal enzyme, palmitoyl protein thioesterase-1 (PPT1). PPT1 knockout mice faithfully reproduce the features of the human disease, with motor deterioration, blindness, seizures, and death before 10 months of age. The progression of events leading from enzyme deficiency to organ failure is poorly defined. The neuronal ceroid lipofuscinoses are of particular interest because of the similarities between the accumulated material and lipofuscin that is associated with normal aging. We will determine changes in gene expression that occur during the course of neurodegeneration in PPT1 knockout as compared to control mice. Gene expression profiling of brain tissue from PPT1 knockout mice as compared to normal controls will provide insights into the mechanism of neurodegeneration. Comparison of this profile with gene expression profiles associated with normal aging may provide insights into the contribution of lipofuscin to aging and neurodegeneration. PPT1 knockout mice on a C57BL/6 background will be sacrificed under CO2 and whole brains removed and frozen under liquid nitrogen. Three mice will be used for each time point. Data points will be collected at 3 months, 5 months and 8 months of age. Normal age- and sex-matched C57BL/6 mice will be used as controls.
Project description:Gene expression profiles were assessed in the hippocampus (HC), entorhinal cortex (EC), superior frontal gyrus (SG), and postcentral gyrus (PCG) across the lifespan of 63 cognitively intact individuals from 20-99 years old. New perspectives on the global gene changes that are associated with brain aging emerged, revealing two overarching concepts. First, different regions of the forebrain exhibited substantially different gene profile changes with age. For example, comparing equally powered groups, 5,029 probe sets were significantly altered with age (20-59 vs. 60-99) in the superior frontal gyrus, compared with 1,110 in the entorhinal cortex. Prominent change occurred in the 6th-7th decades across cortical regions, suggesting that this period is a critical transition point in brain aging, particularly in males. Second, clear gender differences in brain aging were evident across the lifespan, suggesting that the brain undergoes sexually dimorphic changes in gene expression not only in development but also in later life. Globally across all brain regions, males showed more gene change than females. Further, Gene Ontology analysis revealed that different categories of genes were predominantly affected in males vs. females. Notably, the male brain was characterized by global decreased catabolic and anabolic capacity with aging, with downregulated genes heavily enriched in energy production and protein synthesis/transport categories. Increased immune activation was a prominent feature of aging in both sexes, with more widespread activation in the female brain. These data open new opportunities to explore age-dependent changes in gene expression that set the balance between neurodegeneration and compensatory mechanisms in the brain, and suggest that this balance is set differently in males and females, an intriguing and novel idea. HgU133plus2.0 microarray chips were used to profile gene expression in 4 brain regions of cognitively intact humans, across the adult lifespan (ages 20-99). Experiment Overall Design: Postmortem brain tissue was collected from ADRC brain banks. Cases were preferentially selected where 3 or more brain regions were available.