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Small RNA-Seq of the CA1 hippocampal subregion from 3 month and 20 month old animals treated orally with vehicle or SAHA

ABSTRACT: Aging and increased amyloid burden are major risk factors for cognitive diseases such as Alzheimer's Disease (AD). An effective therapy does not yet exist. Here we use mouse models for age-associated memory impairment and amyloid deposition to study transcriptome and cell type-specific epigenome plasticity at the systems level in the brain and in peripheral organs. We show that at the level of epigenetic gene-expression aging and amyloid pathology are associated with inflammation and impaired synaptic function in the hippocampal CA1 region. While inflammation is associated with increased gene-expression that is linked to a subset of transcription factors, de-regulation of plasticity genes is mediated via different mechanisms in the amyloid and the aging model. Amyloid pathology impairs histone-acetylation and decreases expression of plasticity genes while aging affects differential splicing that is linked to altered H4K12 acetylation at the intron-exon junction in neurons but not in non-neuronal cells. We furthermore show that oral administration of the clinically approved histone deacetylase inhibitor Vorinostat not only restores spatial memory, but also exhibits an anti-inflammatory action and reinstates epigenetic balance and transcriptional homeostasis at the level of gene expression and exon usage. This is the first systems-level investigation of transcriptome plasticity in the hippocampal CA1 region in aging and AD models and of the effects of an orally dosed histone deacetylase inhibitor. Our data has important implications for the development of minimally invasive and cost-effective therapeutic strategies against age-associated cognitive decline. In fact, our data strongly suggest to test Vorinostat in patients suffering from AD.

ORGANISM(S): Mus musculus

PROVIDER: GSE63944 | GEO | 2015/08/17

SECONDARY ACCESSION(S): PRJNA269580

REPOSITORIES: GEO

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Project description:Calorie restriction (CR) enhances longevity and mitigates aging phenotypes in numerous species. Physiological responses to CR are cell-type specific and variable throughout the lifespan; however, the mosaic of molecular changes responsible CR benefits remain unclear, particularly in brain regions susceptible to deterioration throughout aging. Thus, we examined the influence of long-term CR on the CA1 hippocampal region, a key learning and memory brain area that is vulnerable to age-related pathologies, such as Alzheimerâs disease (AD). Through mRNA sequencing and NanoString nCounter analysis, we demonstrate that one year of CR feeding suppresses an age-dependent signature of 882 genes functionally associated with synaptic transmission-related pathways, including calcium signaling, long-term potentiation (LTP), and Creb signaling in wild-type mice. By comparing the influence of CR on hippocampal CA1 region transcriptional profiles at younger- (5 months) and older-adult (15 months) timepoints, we identify conserved upregulation of proteome quality control and calcium buffering genes, including heat shock 70 kDa proteins 1b and 5 (Hspa1b and Hspa5), protein disulfide isomerase family A members 4 and 6 (Pdia4 and Pdia6), and calreticulin (Calr). Expression levels of putative neuroprotective factors, klotho (Kl) and transthyretin (Ttr), are also elevated by CR throughout adulthood, although the global CR-specific expression profiles at young and older timepoints are highly divergent. At a previously unachieved resolution, our results demonstrate conserved activation of neuroprotective gene signatures and broad CR-suppression of age-dependent hippocampal CA1 region expression changes, indicating that CR functionally maintains a more youthful transcriptional state within hippocampal CA1 throughout aging. Hippocampal CA1 region mRNA profiles of younger- (5 months) and older-adult (15 months) mice on calorie-restricted (CR) and normal (AD) diets were generated by deep sequencing using Illumina HiSeq 2500.

Project description:The decline of cognitive function is a feature of normal human aging and is exacerbated in AlzheimerM-bM-^@M-^Ys disease (AD). DNA repair declines in brain cells during normal aging and even more so in AD. Here we show that experimental reduction in levels of the base excision repair enzyme, DNA polymerase M-NM-2 (Polb) renders neurons vulnerable to age-related dysfunction and degeneration in a mouse model of AD. Whereas 3xTgAD mice exhibit age-related extracellular amyloid b-peptide (Ab) accumulation and cognitive deficits, but no neuronal death, 3xTg/Polb+/- mice accumulates intracellular Ab and neurons die in the hippocampus and cerebral cortex. The DNA repair-deficient 3xTgAD mice exhibited increased DNA strand breaks and apoptotic caspase activation with loss of hippocampal volume, and impaired synaptic plasticity and memory retention. Molecular profiling revealed remarkable similarities in gene expression alterations in brain cells of AD patients and 3xTgAD/Polb+/- mice including multiple abnormalities suggestive of impaired cellular bioenergetics. Our findings demonstrate that a modest decrement in oxidative DNA damage processing is sufficient to render neurons vulnerable to AD-related pathogenic molecular and cellular alterations that result in the dysfunction and death of neurons, and associated cognitive deficits. 4 mouse strains were used in these experiments, the 3xTgAD and Pol M-NM-2 (+/-) mice were bred at the National Institute on Aging (Baltimore, Maryland). The original line 3xTgAD line was generated as described previously (Oddo, et. al 2003) and possess APPswe, PS1M146V, and tauP301L mutations. DNA polymerase beta heterozygous mice, Pol M-NM-2 (+/-), were crossed with the 3xTgAD mice to generate a 3xTgAD/Pol M-NM-2 (+/-) mouse. The Wt strain is C57Bl/6. At 20 months of age these mice were euthanized by cervical dislocation, the brain removed from the skull and dissected into regions of interest, the prefrontal cortex was used for the microarray studies.

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Small RNA-Seq of the CA1 hippocampal subregion from 3 month and 20 month old animals treated orally with vehicle or SAHA

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