Dataset Information

Bmi1 is down-regulated in the aging brain and displays antioxidant and protective activities in neurons.

ABSTRACT: Aging increases the risk to develop several neurodegenerative diseases, although the underlying mechanisms are poorly understood. Inactivation of the Polycomb group gene Bmi1 in mice results in growth retardation, cerebellar degeneration, and development of a premature aging-like phenotype. This progeroid phenotype is characterized by formation of lens cataracts, apoptosis of cortical neurons, and increase of reactive oxygen species (ROS) concentrations, owing to p53-mediated repression of antioxidant response (AOR) genes. Herein we report that Bmi1 expression progressively declines in the neurons of aging mouse and human brains. In old brains, p53 accumulates at the promoter of AOR genes, correlating with a repressed chromatin state, down-regulation of AOR genes, and increased oxidative damages to lipids and DNA. Comparative gene expression analysis further revealed that aging brains display an up-regulation of the senescence-associated genes IL-6, p19(Arf) and p16(Ink4a), along with the pro-apoptotic gene Noxa, as seen in Bmi1-null mice. Increasing Bmi1 expression in cortical neurons conferred robust protection against DNA damage-induced cell death or mitochondrial poisoning, and resulted in suppression of ROS through activation of AOR genes. These observations unveil that Bmi1 genetic deficiency recapitulates aspects of physiological brain aging and that Bmi1 over-expression is a potential therapeutic modality against neurodegeneration.

SUBMITTER: Abdouh M

PROVIDER: S-EPMC3285640 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Bmi1 is down-regulated in the aging brain and displays antioxidant and protective activities in neurons.

Abdouh Mohamed M Chatoo Wassim W El Hajjar Jida J David Jocelyn J Ferreira José J Bernier Gilbert G

PloS one 20120223 2

Aging increases the risk to develop several neurodegenerative diseases, although the underlying mechanisms are poorly understood. Inactivation of the Polycomb group gene Bmi1 in mice results in growth retardation, cerebellar degeneration, and development of a premature aging-like phenotype. This progeroid phenotype is characterized by formation of lens cataracts, apoptosis of cortical neurons, and increase of reactive oxygen species (ROS) concentrations, owing to p53-mediated repression of antio ...[more]

PMID: 22384090

Similar Datasets

Project description:BackgroundHomozygotic mutations in the GBA gene cause Gaucher's disease; moreover, both patients and heterozygotic carriers have been associated with 20- to 30-fold increased risk of developing Parkinson's disease. In homozygosis, these mutations impair the activity of β-glucocerebrosidase, the enzyme encoded by GBA, and generate a lysosomal disorder in macrophages, which changes morphology towards an engorged phenotype, considered the hallmark of Gaucher's disease. Notwithstanding the key role of macrophages in this disease, most of the effects in the brain have been attributed to the β-glucocerebrosidase deficit in neurons, while a microglial phenotype for these mutations has never been reported.MethodsWe applied the bioluminescence imaging technology, immunohistochemistry and gene expression analysis to investigate the consequences of microglial β-glucocerebrosidase inhibition in the brain of reporter mice, in primary neuron/microglia cocultures and in cell lines. The use of primary cells from reporter mice allowed for the first time, to discriminate in cocultures neuronal from microglial responses consequent to the β-glucocerebrosidase inhibition; results were finally confirmed by pharmacological depletion of microglia from the brain of mice.ResultsOur data demonstrate the existence of a novel neuroprotective mechanism mediated by a direct microglia-to-neuron contact supported by functional actin structures. This cellular contact stimulates the nuclear factor erythroid 2-related factor 2 activity in neurons, a key signal involved in drug detoxification, redox balance, metabolism, autophagy, lysosomal biogenesis, mitochondrial dysfunctions, and neuroinflammation. The central role played by microglia in this neuronal response in vivo was proven by depletion of the lineage in the brain of reporter mice. Pharmacological inhibition of microglial β-glucocerebrosidase was proven to induce morphological changes, to turn on an anti-inflammatory/repairing pathway, and to hinder the microglia ability to activate the nuclear factor erythroid 2-related factor 2 response, thus increasing the neuronal susceptibility to neurotoxins.ConclusionThis mechanism provides a possible explanation for the increased risk of neurodegeneration observed in carriers of GBA mutations and suggest novel therapeutic strategies designed to revert the microglial phenotype associated with β-glucocerebrosidase inhibition, aimed at resetting the protective microglia-to-neuron communication.

Project description:Age is the primary risk factor for many chronic diseases and cognitive decline during brain aging may increase dementia risk. Hallmarks of brain aging including neuronal dysfunction and glial contribute to reduced cognitive function, and there is a persistent lack of effective treatments. Bioactive plant compounds called “nutraceuticals” can target age-related cellular processes and may protect cognitive function. Apigenin is a flavone found in plants such as chamomile and can inhibit hallmarks of aging such as cellular senescence, mitochondrial dysfunction, and impaired proteostasis. However, the underlying mechanisms of apigenin in the brain are not fully understood. Here, we characterized brain transcriptome changes in young and old mice given apigenin in drinking water and examined potential mechanisms in human astrocytes. Consistent with previous studies, we observed improved novel object recognition in old mice treated with apigenin versus old controls. Transcriptome analyses in old controls found differentially expressed genes related to immune responses, inflammation, and cytokine regulation versus young. Fewer differences were observed in old apigenin-treated versus old controls, but these changes were related to development, behavior, and antiviral responses. The majority of upregulated genes in old mice were downregulated with apigenin treatment and associated with immune responses. Similarly, the genes that were reduced with aging, but increased in old apigenin-treated mice were related to pathways important for neurological function/disease, cellular maintenance, and homeostatic signaling. We also found that glial cells drove the majority of the transcriptome differences with aging and apigenin-treatment. To explore the mechanism of action for apigenin in glial cells, we treated replicatively aged astrocytes with apigenin and observed reduced markers of inflammation and cellular senescence. Collectively, our data support the role of apigenin as a protector of cognitive and neuronal function protectant through the suppression of neuroinflammatory genes and proteins and may be especially important in non-neuronal cells.

Dataset Information

Bmi1 is down-regulated in the aging brain and displays antioxidant and protective activities in neurons.

Publications

Bmi1 is down-regulated in the aging brain and displays antioxidant and protective activities in neurons.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure