Project description:We aimed at investigating the function of TIP60 in the in the mammalian hippocampus. For this, we used mice with a forebrain-specific deletion of Tip60 upon tamoxifen injection (Tip60 cKO). RNA-sequencing was applied to examine the transcriptome changes in the CA1 region upon Tip60 deletion. We observed massive transcriptional changes and identified a neurodegeneration-related signature at a time when there are no obvious morphological changes in Tip60 cKO mice. Later on these mice develop extensive neurodegeneration in hippocampal CA1.
Project description:The Tip60 (also known as Kat5) lysine acetyltransferase functions broadly as a transcriptional co-activator that acetylates histones. In contrast, Tip60 functions in embryonic stem cells (ESCs) both to silence genes that promote differentiation and to activate genes required for proliferation. The mechanism by which Tip60 functions as a repressor is unknown. Here we show that the class II histone deacetylase Hdac6 co-purifies with Tip60-p400 complex from ESCs and is necessary for complete silencing of most differentiation genes targeted by Tip60. In contrast to differentiated cells, where Hdac6 is mainly cytoplasmic and does not interact with Tip60, Hdac6 is largely nuclear in ESCs and neural stem cells (NSCs) and interacts with Tip60-p400 in both cell types. Hdac6 is enriched at promoters bound by Tip60-p400 in ESCs, but while Tip60 binds on both sides of transcription start sites (TSSs), Hdac6 binding overlaps with only the downstream Tip60 peak. Surprisingly, Hdac6 does not deacetylate histones at these sites, but rather is required for Tip60 binding. These data suggest that nuclear exclusion of Hdac6 during differentiation plays a major role in modulation of Tip60-p400 function. We determined the genome-wide localization of Tip60 and Hdac6 in mouse ES cells, and examined genomic binding profiles of Tip60 and Hdac6 upon indicated knockdown by ChIP-seq. We examined genomic binding profiles of p400 upon indicated knockdown by ChIP-seq.
Project description:Mechanistic study on the differential responses of the two hippocampal adjoining regions, i.e., CA1 and CA3, to elevated oxidative stress. Keywords: Time course stress response study
Project description:KAT5 encodes an essential lysine acetyltransferase previously called TIP60 involved in gene expression, DNA repair, chromatin remodeling, apoptosis and cell proliferation; but it remains unclear whether variants in this gene causes a genetic disease. Here, we study three individuals with heterozygous de novo missense variants in KAT5 that affect normally invariant residues, with one at the chromodomain (p.Arg53His) and two at or near the acetyl-CoA binding site (p.Cys369Ser and p.Ser413Ala). All three individuals have cerebral malformations, seizures, global developmental delay or intellectual disability, and severe sleep disturbance. Progressive cerebellar atrophy was also noted. Histone acetylation assays with purified mutant KAT5 demonstrated that the variants decrease or abolish the ability of the resulting NuA4/TIP60 multi-subunit complexes to acetylate the histone H4 tail in chromatin. Transcriptomic analysis in patient-derived fibroblasts showed deregulation of multiple genes controlling development. Moreover, there was also upregulated expression of PER1 (a key gene involved in circadian control), in agreement with sleep anomalies in all the patients. In conclusion, dominant missense KAT5 variants cause histone acetylation deficiency with transcriptional dysregulation of multiples genes, thereby leading to a neurodevelopmental syndrome with sleep disturbance, cerebellar atrophy and facial dysmorphisms suggesting a recognizable syndrome.
Project description:Metabolic, mitochondrial and behavioral correlations with transcriptional profiles from the CA1 and DG hippocampal regions of young and aged rhesus macaque. Increasing evidence indicates that obesity correlates with impaired cognitive performance during normal aging and is a major risk factor for Alzheimer’s disease. However, little is known regarding how peripheral metabolic variables affect cellular pathways in brain regions important for memory. Brain inflammation, mitochondrial dysregulation, and altered transcriptional regulation have all been found to occur with aging, and recent microarray analyses in rodent models have linked these processes and others to age-related memory impairment. However, whether these brain changes are also associated with metabolic variables is not known. Aging monkeys exhibit several metabolic changes similar to those seen in humans. Here, we tested peripheral-brain relationships in six young (7.0 +/- 0.3 years) and six aged (23.5 +/- 0.7 years) female rhesus monkeys. Animal cognition was gauged with a variable delay task; blood constituents were assessed with a serum chemistry panel emphasizing markers of metabolic dysfunction; mitochondrial function was measured from the hippocampus of one hemisphere; and the CA1 and dentate gyrus regions of the other hippocampus were dissected out for gene expression microarray analysis. Aged animals showed reduced performance on the behavioral task, exhibited aspects of metabolic dysregulation including increased insulin, triglyceride, and chylomicron levels (consolidated into a peripheral metabolic index), and showed a significant age-related reduction in State III oxidation, a measure of mitochondrial function. Microarray analyses revealed hundreds of genes that correlated with the peripheral metabolic index. However, DAVID statistical pathway analyses showed that upregulated inflammatory genes in CA1 and downregulated transcriptional regulation genes in dentate gyrus and CA1 were particularly overrepresented among genes correlated with the peripheral index. Thus, the association of metabolic variables with specific neuropathological processes in different regions of the hippocampal formation may have implications for mechanisms through which peripheral metabolism alters the risk for Alzheimer’s disease. Keywords: Rhesus hippocampal aging
Project description:Aging is associated with a decline in hippocampal mediated learning and memory, a process which can be ameliorated by dietary (caloric) restriction. We used Affymetrix gene expression analysis to monitor changes in three regions of the hippocampus (CA1, CA3, DG) of middle aged (18 months) and old (28 month) rats that were exposed to dietary restriction. Old rats were determined to be good performers (GP) or poor performers (PP) in behavioural tests to assess their hippocampal function. We used Affymetrix gene expression analysis to monitor changes in three regions of the hippocampus (CA1, CA3, DG) of middle aged (18 months) and old (28 month) rats that were exposed to dietary restriction.
Project description:The goal of our study was to assess whether the experience can regulate specific lncRNAs within the hippocampus and their role in associative memory. To address this, we carried out unbiased analyses of gene expression in CA1-hippocampal neurons to identify lncRNA changes induced by contextual fear conditioning (CFC).