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Unknown,Transcriptomics,Genomics,Proteomics

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Progranulin Deficiency Promotes Circuit-Specific Synaptic Pruning by Microglia via Complement Activation

ABSTRACT: Microglia repair injury and maintain homeostasis in the brain, but whether aberrant microglial activation can contribute to neurodegeneration remains unclear. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive up-regulation of lysosomal and innate immunity genes, increased complement production, and synaptic pruning activity in microglia. During aging, Grn-/- mice show profound accumulation of microglia and preferential elimination of inhibitory synapses in the ventral thalamus, which contribute to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors. Remarkably, blocking complement activation by deleting C1qa gene significantly reduces synaptic pruning by Grn-/- microglia, and mitigates neurodegeneration, behavioral phenotypes and premature mortality in Grn-/- mice. These results uncover a previously unrecognized role of progranulin in suppressing microglia activation during aging, and support the idea that blocking complement activation is a promising therapeutic target for neurodegeneration caused by progranulin deficiency. Gene expression study in multiple brain regions from a mouse model of progranulin deficiency Please note that 9 outlier samples were excluded from data analysis. Therefore, there are 326 raw data columns (i.e. 163 samples) in the non_normalized data matrix while 154 samples are represented here.

ORGANISM(S): Mus musculus

SUBMITTER: Giovanni Coppola

PROVIDER: E-GEOD-75083 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Progranulin Deficiency Promotes Circuit-Specific Synaptic Pruning by Microglia via Complement Activation

Project description:Microglia repair injury and maintain homeostasis in the brain, but whether aberrant microglial activation can contribute to neurodegeneration remains unclear. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive up-regulation of lysosomal and innate immunity genes, increased complement production, and synaptic pruning activity in microglia. During aging, Grn-/- mice show profound accumulation of microglia and preferential elimination of inhibitory synapses in the ventral thalamus, which contribute to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors. Remarkably, blocking complement activation by deleting C1qa gene significantly reduces synaptic pruning by Grn-/- microglia, and mitigates neurodegeneration, behavioral phenotypes and premature mortality in Grn-/- mice. These results uncover a previously unrecognized role of progranulin in suppressing microglia activation during aging, and support the idea that blocking complement activation is a promising therapeutic target for neurodegeneration caused by progranulin deficiency.

2016-03-31 | GSE75083 | GEO

Mus musculus

Project description:Progranulin Deficiency Promotes Circuit-Specific Synaptic Pruning by Microglia via Complement Activation

| PRJNA302422 | ENA

Protein expression in the prefrontal cortex of aged mice with progranulin deficiency or neuronal progranulin overexpression

Project description:Description: Progranulin deficiency is associated with neurodegeneration in humans and in mice. We performed a deep proteomic screen of the pre-frontal cortex in aged (13-15 months) female progranulin-deficient mice (GRN-/-) and mice with a neuron-specific inducible overexpression of progranulin (SLICK-GRN-OE with tamoxifen) versus the respective control mice (Grn+/+ and SLICK-Grn without Tamoxifen). The data set shows progranulin-dependent alterations of protein expression in the cortex of mice.

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Project description:Patients with frontotemporal dementia (FTD) resulting from granulin (GRN) haploinsufficiency have reduced levels of progranulin and exhibit dysregulation in inflammatory and lysosomal networks. Microglia produce high levels of progranulin, and reduction of progranulin in microglia alone is sufficient to recapitulate inflammation, lysosomal dysfunction, and hyperproliferation in a cell-autonomous manner. Therefore, targeting microglial dysfunction caused by progranulin insufficiency represents a potential therapeutic strategy to manage neurodegeneration in FTD. Limitations of current progranulin-enhancing strategies necessitate the discovery of new targets.To identify compounds that can reverse microglial defects in Grn-deficient mouse microglia, we performed a compound screen coupled with high throughput sequencing to assess key transcriptional changes in inflammatory and lysosomal pathways. Positive hits from this initial screen were then further narrowed down based on their ability to rescue cathepsin activity, a critical biochemical readout of lysosomal capacity. The screen identified nor-binaltorphimine dihydrochloride (nor-BNI) and dibutyryl-cAMP, sodium salt (DB-cAMP) as two phenotypic modulators of progranulin deficiency. In addition, nor-BNI and DB-cAMP also rescued cell cycle abnormalities in progranulin-deficient cells. These data highlight the potential of a transcription-based platform for drug screening, and advance two novel lead compounds for FTD.

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Opposite microglial activation stages upon loss of PGRN result in reduced cerebral glucose metabolism

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Antisense oligonucleotides targeting the miR-29b binding site in the GRN mRNA increase progranulin translation

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