Reversal of Synapse Loss in Alzheimer Mouse Models by Targeting mGluR5 to Prevent Synaptic Tagging by C1q
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA834138 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR19042202.fastq.gz | Fastqsanger.gz | |||
| SRR19042302.fastq.gz | Fastqsanger.gz | |||
| SRR19042205.fastq.gz | Fastqsanger.gz | |||
| SRR19042305.fastq.gz | Fastqsanger.gz | |||
| SRR19042207.fastq.gz | Fastqsanger.gz |
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Project description:Synapse loss and glial activation are hallmarks of Alzheimer's disease (AD). In Tau P301S transgenic mice, the complement pathway contributes to neuronal damage through microglial elimination of synapses. Here, we used unbiased proteomic profiling of postsynaptic density (PSD) fractions from Tau P301S mice in C1q-WT versus C1q knockout backgrounds to identify C1q-dependent changes at synapses. Integrative multi-omics analysis revealed that astrocyte- and microglia- specific proteins are increased in Tau P301S synapse fractions with age and in a C1q-dependent manner. The same set of glial proteins (including C1q, C4, Gpnmb, and S100a4) is elevated in human AD synaptic fractions, and C4 levels are raised in cerebrospinal fluid (CSF) from AD patients. Besides microglia, we show that astrocytes contribute substantially to excitatory and inhibitory synapse engulfment in Tau P301S hippocampus. Based on staining of synapse markers within lysosomes, astrocytes showed preference for excitatory synapses whereas microglia preferred to engulf inhibitory synapse markers. Genetic deletion of C1q reduced astrocytic eating of excitatory and inhibitory synapses in Tau P301S mice, and rescued synapse density. Together, our data indicate that astrocytes contact and phagocytose synapses in a C1q- dependent manner and thereby contribute to synapse loss and neurodegeneration in AD.
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Project description:We have data from a previous microarray experiment which shows that C1q elicits macrophages to express genes important for clearance of dead (apoptotic) cells. In this experiment we want to determine the signaling mechanism by which C1q is turning on macrophage gene expression. For our control (sample 1-3) we heated C1q to denature it so it is inactive. We also want to know which portion of C1q is responsible for activation the macrophage so we generated C1qtails (samples 4-5). We also have macrophages treated with the whole C1q molecule (7-9). And finally we have a cell line (J774) treated with C1q but does not activate the cells (samples 10-12).
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Project description:The metabotropic glutamate receptor 5 (mGluR5) is a G-protein coupled receptor with an important role in synaptic function at multiple levels. In physiological conditions, mGluR5 is an essential modulator of synaptic plasticity, learning and memory; whereas in pathological conditions, it is an acknowledged therapeutic target that has been implicated in multiple brain disorders. However, the underlying mechanisms by which mGluR5 acts in these diverse synaptic functions and processes is only partly understood. In this study, we dissected the molecular synaptic modulation mediated by mGluR5 using genetic and pharmacological mouse models to chronically and acutely reduce mGluR5 activity. Using SWATH proteomic analysis, we found that next to dysregulation of synaptic proteins, the major regulation in protein expression in both models concerned specific processes in mitochondria, such as oxidative phosphorylation. Second, we observed morphological alterations in shape and area of specifically postsynaptic mitochondria in mGluR5 KO synapses using electron microscopy. Third, computational and biochemical assays suggested an increase of mitochondrial function in neurons, with increased level of NADP/H and oxidative damage in mGluR5 KO. Altogether, our observations provide diverse lines of evidence of the modulation of synaptic mitochondrial function by mGluR5. This connection suggests a role for mGluR5 as a mediator between synaptic activity and mitochondrial function, a finding which might be a relevant for the improvement of the clinical potential of mGluR5.
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