The role of Rack1 in microglia in AD
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE256191 | GEO | 2024/06/30
REPOSITORIES: GEO
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Project description:Microglia, the innate immune cells of the central nervous system, perform critical inflammatory and non-inflammatory functions to maintain homeostasis and normal neural function. However in Alzheimer’s disease (AD), these beneficial functions become progressively impaired, contributing to synapse and neuron loss and cognitive impairment. The inflammatory cyclooxygenase-PGE2 pathway, including the PGE2 receptor EP2, is implicated in AD development, both in human epidemiology and in transgenic models of AD. To test the transcriptional responses of EP2-deficient microglia to Aβ in vivo, we used mice in which the EP2 receptor is conditionally deleted in microglia using the CD11b-Cre transgene and floxed alleles of the EP2 gene. By injecting these mice with Aβ ICV and isolating microglia from the brains, we have been able to establish the transcriptional response of microglia to Aβ in vivo and test how EP2 deletion in microglia affects this response. 8 month-old C57BL/6 mice, of the genotype CD11b-Cre; EP2+/+ or CD11b-Cre; EP2lox/lox, were injected I.C.V. with either Aβ or vehicle. 48 hours after injection, the mice were sacrificed and transcardially perfused with cold heparinized 0.9% NaCl. Brains were then removed from the mice and pooled, two brains of the same genotype per sample, to ensure adequate cell and RNA yield. The brains were then enzymatically dissociated for microglia isolation using the Neural Tissue Dissociation Kit (P), MACS Separation Columns (LS), and magnetic CD11b Microbeads from Miltenyi Biotec according to the manufacturer's protocol. Immediately after isolating the microglia, RNA was extracted from the cells for microarray analysis.
2015-02-20 | E-GEOD-57181 | biostudies-arrayexpress
Project description:MicroRNAs (miRNAs) regulate plant development by post-transcriptional regulation of target genes. In Arabidopsis thaliana, DCL1 processes precursors (pri-miRNAs) to miRNA duplexes, which associate with AGO1. Additional proteins act in concert with DCL1 (e.g. HYL1 and SERRATE) or AGO1, respectively, to facilitate efficient and precise pri-miRNA processing and miRNA loading. In this study, we show that the accumulation of plant microRNAs depends on RECEPTOR FOR ACTIVATED C KINASE 1 (RACK1), a scaffold protein found in all higher eukaryotes. miRNA levels are reduced in rack1 mutants and our data suggest that RACK1 affects the microRNA pathway via several distinct mechanisms involving direct interactions with known microRNA factors: RACK1 ensures the accumulation and processing of some pri-miRNAs, directly interacts with SERRATE and is part of an AGO1 complex. As a result, mutations in RACK1 lead to misregulation of miRNA target genes, which is important for ABA responses and phyllotaxy. In conclusion, our study discovered complex functioning of RACK1 proteins in the Arabidopsis miRNA pathway, which are important for miRNA production and therefore plant development.
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Project description:We define a pathogenic subset of microglia that is distinguished by expression of the CD11c protein and by production of osteopontin (OPN). OPN production by this CD11c+ microglial subset correlates positively with disease pathology and severity in the 5XFAD mouse model and in AD patients. Genetic ablation of OPN in 5XFAD mice leads to reduced development of pro-inflammatory CD11c+ microglia, increased amyloid beta (Aβ) phagocytosis and improved cognitive function.
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Project description:MicroRNAs (miRNAs) regulate different aspects of plant development by post-transcriptional regulation of target genes. In Arabidopsis, DICER-LIKE 1 (DCL1) processes miRNA precursors (pri-miRNAs) to miRNA duplexes, which associate with ARGONAUTE 1 (AGO1). AGO1 together with the miRNA guide strand binds complementary RNA sequences within target mRNAs. Additional proteins act in concert with DCL1 (e.g. HYL1 and SERRATE) and AGO1, respectively, to facilitate efficient and precise pri-miRNA processing and loading into the effector protein. Here, we show that RECEPTOR OF ACTIVATED C KINASE 1 (RACK1) is a novel component of the Arabidopsis miRNA pathway. RACK1 is a seven-bladed WD-repeat protein that has previously been shown to act as a scaffold protein mediating multiple simultaneous protein-protein interactions. Our molecular analyses demonstrate that RACK1 function is required for controlling miRNA-mediated gene expression. rack1 mutants contain only low levels of mature miRNAs without affecting the first step of pri-miRNA processing. Physical and genetic interaction studies revealed that RACK1 acts in concert with AGO1 and also interacts with a SERRATE, a component of the miRNA processing machinery. These results suggest that RACK1 also functions as a scaffold protein in the miRNA pathway to orchestrates miRNA maturation steps after the initial events of pri-miRNA processing. sequencing of small RNAs from WT and rack1abc mutants (two biological replicates each)
2013-07-01 | E-GEOD-40579 | biostudies-arrayexpress
Project description:Polygenic risk scores have identified that genetic variants without genome-wide significance still add to the genetic risk of developing Alzheimer’s disease (AD). Whether and how subthreshold risk loci translate into relevant disease pathways, is unknown. We investigate here the involvement of AD risk variants in the transcriptional responses of two mouse models: APPswe/PS1L166P and Thy-TAU22. A unique gene expression module, highly enriched for AD risk genes, is specifically responsive to Aβ but not TAU pathology. We identify in this module 7 established AD risk genes (APOE, CLU, INPP5D, CD33, PLCG2, SPI1 and FCER1G) and 11 AD GWAS genes below the genome-wide significance threshold (GPC2, TREML2, SYK, GRN, SLC2A5, SAMSN1, PYDC1, HEXB, RRBP1, LYN and BLNK), that become significantly upregulated when exposed to Aβ. Single microglia sequencing confirms that Aβ, not TAU, pathology induces marked transcriptional changes in microglia, including increased proportions of activated microglia. We conclude that genetic risk of AD functionally translates into different microglia pathway responses to Aβ pathology, placing AD genetic risk downstream of the amyloid pathway but upstream of TAU pathology.
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Project description:Polygenic risk scores have identified that genetic variants without genome-wide significance still add to the genetic risk of developing Alzheimer’s disease (AD). Whether and how subthreshold risk loci translate into relevant disease pathways, is unknown. We investigate here the involvement of AD risk variants in the transcriptional responses of two mouse models: APPswe/PS1L166P and Thy-TAU22. A unique gene expression module, highly enriched for AD risk genes, is specifically responsive to Aβ but not TAU pathology. We identify in this module 7 established AD risk genes (APOE, CLU, INPP5D, CD33, PLCG2, SPI1 and FCER1G) and 11 AD GWAS genes below the genome-wide significance threshold (GPC2, TREML2, SYK, GRN, SLC2A5, SAMSN1, PYDC1, HEXB, RRBP1, LYN and BLNK), that become significantly upregulated when exposed to Aβ. Single microglia sequencing confirms that Aβ, not TAU, pathology induces marked transcriptional changes in microglia, including increased proportions of activated microglia. We conclude that genetic risk of AD functionally translates into different microglia pathway responses to Aβ pathology, placing AD genetic risk downstream of the amyloid pathway but upstream of TAU pathology.
2020-01-14 | GSE110741 | GEO
Project description:Scope: As a result of population ageing, the number of Alzheimer’s disease (AD) patients has rapidly increased. There are many hypothesises on the pathogenesis of AD, but its detailed molecular mechanism is still unknown, and so no effective preventive or therapeutic measures have been established. Some reports showed a decrease in levels of norepinephrine (NE) has been suspected to be involved in the decline of cognitive function in AD patients and NE concentrations were decreased in postmortem AD patient brains. Tyr-Trp was identified as being the most effective dipeptide in enhancing norepinephrine (NE) synthesis and metabolism. And Tyr-Trp treatment ameliorated the short-term memory dysfunction in AD model mice caused by amyloid beta (Aβ) 25-35. So, the purpose of this study was to investigate the preventive or/and protective effects of Tyr-Trp administration in AD model mice. Methods and results: ddY mice were fed normal diet. After 7 days of feeding, mice were divided into 3 groups (n=10 per group) as follows: the sham group, which received saline administration and distilled water injection; the Aβ group, which received saline administration and Aβ peptides 25–35 injection; and the Aβ+YW group, which received Tyr-Trp administration and Aβ peptides 25–35 injection. Tyr-Trp was orally administered Tyr-Trp (100 mg kg-1 day-1, twice a day), starting 7 days before Aβ peptides injection. The other groups received oral administration of saline (5 mL kg-1). After Aβ peptides injection or sham operation, each groups received every oral administration. DAN microarray showed that Tyrosine hydroxylase, dopa decarboxylase and dopamine receptor D2 mRNA expressions which were downregulated in Aβ group comparing with sham group were upregulated in Aβ+YW group comparing with Aβ group. In addition, quinoid dihydropteridine reductase mRNA expression which wasn’t changed in Aβ group comparing with sham group was upregulated in Aβ+YW group comparing with Aβ group. Conclusions: These results suggest that Tyr-Trp administration might ameliorate the short-term memory dysfunction in AD model mice because of enhancing norepinephrine (NE) synthesis and metabolism through metabolism of both Tyr and Trp.
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