Project description:Alzheimer's disease is a neurological disorder characterized by the overproduction and aggregation of amyloid-beta and the phosphorylation and intraneuronal accumulation of tau. These events promote synaptic dysfunction and loss, leading to neurodegeneration and cognitive deficits. Astrocytes are intimately associated with synapses and become activated under pathological conditions, becoming neurotoxic and detrimentally affecting synapses. Although it has been established that reducing neuronal tau expression prevents amyloid-beta-induced toxicity, the role of astrocytic tau in this setting remains understudied. Herein, we performed a series of astrocytic and neuronal primary cultures to evaluate the effects of decreasing astrocytic tau levels on astrocyte-mediated amyloid-beta-induced synaptic degeneration. Our results suggest that the downregulation of tau in astrocytes mitigates the loss of synapses triggered by their exposure to amyloid-beta. Additionally, the absence of tau from astrocytes promotes the upregulation of several synaptoprotective genes, followed by increased production of the neuroprotective factor Pentraxin 3. These results expand our understanding of the contribution of astrocytic tau to the neurodegenerative process induced by amyloid-beta-stimulation and how reducing astrocytic tau could improve astrocyte function by stimulating the expression of synaptoprotective factors. Reducing endogenous astrocytic tau expression could be a potential strategy to prevent synaptic damage in Alzheimer's disease and other neurological conditions.
Project description:To understand how glia may be altered in frontotemporal degeneration with tau pathology (FTD-tau), we used a NanoString glial profiling panel to measure 770 transcripts related to glial biology in human control (n = 8), Alzheimer’s disease (AD) (n = 8), and FTD-tau (n = 8) dorsolateral prefrontal cortex. Compared to control, 43 genes were upregulated and 86 genes were downregulated in the FTD-tau samples. Only 3 genes were upregulated and 2 were downregulated in AD. Pathway analysis revealed many astrocyte-, microglia-, and oligodendrocyte-related pathway scores increased in FTD-tau, while neuron-related pathway scores decreased. We compared these results to a previously published proteomic dataset containing many of the same samples and found that the targeted panel approach obtained measurements for genes whose proteins were not measured in the proteomics. Our results point to the utility of multi-omic approaches and marked dysregulation of glia in FTD-tau.
Project description:The abnormal regulation of amyloid-b (Ab) metabolism (e.g., production, cleavage, clearance) plays a central role in Alzheimer’s disease (AD). Among endogenous factors believed to participate in AD progression are the small regulatory non-coding microRNAs (miRs). In particular, the miR-132/212 cluster is severely reduced in the AD brain. In previous studies we have shown that miR-132/212 deficiency in mice leads to impaired memory and enhanced Tau pathology as seen in AD patients. Here we demonstrate that the genetic deletion of miR-132/212 promotes Ab deposition and amyloid (senile) plaque formation in triple transgenic AD (3xTg-AD) mice. Using RNA-Seq and bioinformatics, we identified genes of the miR-132/212 network with documented roles in the regulation of Ab metabolism, including Tau, Mapk, and Sirt1.
Project description:The abnormal regulation of amyloid-b (Ab) metabolism (e.g., production, cleavage, clearance) plays a central role in Alzheimerâs disease (AD). Among endogenous factors believed to participate in AD progression are the small regulatory non-coding microRNAs (miRs). In particular, the miR-132/212 cluster is severely reduced in the AD brain. In previous studies we have shown that miR-132/212 deficiency in mice leads to impaired memory and enhanced Tau pathology as seen in AD patients. Here we demonstrate that the genetic deletion of miR-132/212 promotes Ab deposition and amyloid (senile) plaque formation in triple transgenic AD (3xTg-AD) mice. Using RNA-Seq and bioinformatics, we identified genes of the miR-132/212 network with documented roles in the regulation of Ab metabolism, including Tau, Mapk, and Sirt1. We used RNA-Seq to analyse the hippocampus of 3xTg-AD mice lacking the miR-132/212 cluster as well as Neuro2a cells overexpressing miR-132 mimics.
Project description:Glial profiling of human tauopathy brain demonstrates enrichment of astrocytic transcripts in tau-related frontotemporal degeneration
Project description:We performed H3K9me2-based ChIP-seq to identify regions of the Drosophila genome that are H3K9me2-depleted due to transgenic neuronal expression of human mutant tau. Examination of H3K9me2 histone methylation in 10 day old control and tau transgenic Drosophila heads.
Project description:Mutations of the β-glucuronidase protein α-Klotho have been associated with premature aging, and altered cognitive function. Although highly expressed in specific areas of the brain, Klotho functions in the central nervous system remain unknow. Here, we show that cultured hippocampal neurons respond to insulin and glutamate stimulation by elevating Klotho protein levels. Conversely, AMPA and NMDA antagonism suppress neuronal Klotho expression. We also provide evidence that soluble Klotho enhances astrocytic aerobic glycolysis by hindering pyruvate metabolism through the mitochondria, and stimulating its processing by lactate dehydrogenase. Pharmacological inhibition of FGFR1, Erk phosphorylation, and monocarboxylic acid transporters prevents Klotho-induced lactate release from astrocytes. Taken together these data suggest Klotho is a potential new player in the metabolic coupling between neurons and astrocytes. Neuronal glutamatergic activity and insulin modulation elicit Klotho release, which in turn stimulates astrocytic lactate formation and release. Lactate can then be used by neurons as a metabolic substrate contributing to fulfill their elevated energy requirements.
Project description:Many RNA-binding proteins (RBPs), particularly those associated with RNA granules, promote pathological protein aggregation in neurodegenerative diseases. Here, we demonstrate that G3BP2, a core component of stress granules, directly interacts with Tau and inhibits Tau aggregation. In the human brain, the interaction of G3BP2 and Tau is dramatically increased in multiple Tauopathies and precedes neurofibrillary tangle (NFT) formation in Alzheimer’s disease (AD). Surprisingly, Tau pathology is significantly elevated upon loss of G3BP2 in human neurons and brain organoids. Moreover, we find that G3BP2 masks the microtubule-binding region (MTBR) of Tau, thereby inhibiting Tau aggregation. Our study defines a novel role for RBPs as a line of defense against Tau aggregation in Tauopathies.