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Gene expression changes in the course of normal brain aging are sexually dimorphic

ABSTRACT: This dataset of cognitively normal controls is a subset of the GSE48350 dataset, which additionally contains microarray data from AD brains. 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. Keywords: Normal gene expression patterns across the adult lifespan

ORGANISM(S): Homo sapiens

PROVIDER: GSE11882 | GEO | 2008/10/09

SECONDARY ACCESSION(S): PRJNA105699

REPOSITORIES: GEO

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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.

Project description:Per- and polyfluoroalkyl substances (PFAS) are persistent pollutants known for their bio-accumulative properties and prevalence in water supplies and household products. Although legacy PFAS, such as perfluorooctanoic acid, are phased out in the U.S. due to public health concerns, a PFAS variant hexafluoropropylene oxide-dimer acid (HFPO-DA) is an emerging replacement. HFPO-DA is a potential neurotoxicant that has been shown to cause dopaminergic neurodegeneration. We investigated the bioaccumulative potential of HFPO-DA and its effects on lifespan, locomotor activity, and brain gene expression in female and male Drosophila melanogaster (fruit flies). Flies were collected less than 4 hours post-eclosion and exposed to 0, 10, 10^2, 10^3, or 10^4 mg/kg/day HFPO-DA. To measure the effect of HFPO-DA on lifespan, surviving flies from each exposure were recorded every 24 hours. Flies were subjected to a negative geotaxis assay at 3, 7, and 14 days of exposure to measure the effects of acute, sub-chronic, and chronic exposures on locomotor ability. To capture HFPO-DA-induced sexually dimorphic gene expression responses in the brain, we sequenced brain-specific mRNA from flies exposed for 3, 7, or 14 days. The Bioconcentration Factor was 0.031 for females, and 0.026 for males. Dose and median lifespan were negatively correlated in both female (R^2 adj = 0.77, p<0.0001) and male flies (R^2 adj = 0.77, p<0.0001). Log-rank Mantel-Cox tests and one-way ANOVAs revealed that median lifespan was reduced in females starting at 10 mg/kg/day and in males starting at 10^2 mg/kg/day (p< 0.01). Acute exposure at 10 mg/kg/day significantly decreased locomotor ability in females (p<0.0001) while acute exposures at 1 mg/kg/day decreased locomotor activity in males (p <0.0001). Among 7500 genes analyzed, pairwise gene expression comparison between controls and treatments identified 2496 differentially expressed genes. While HFPO-DA does not readily bioaccumulate in fruit fly bodies, high-dose exposures have sex-specific effects on lifespan, locomotor ability, and brain gene expression. LOAEL for median lifespan is 10 mg/kg/day in females, and 10^2 mg/kg/day in males. Both locomotor ability and brain gene expression exhibited non-conventional dose-response as seen in other endocrine disrupting chemical exposures.

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Gene expression changes in the course of normal brain aging are sexually dimorphic

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