A persistent and non-resolving inflammatory response to accumulating A peptide species is a cardinal feature in the development of Alzheimer's disease (AD). In response to accumulating A peptide species, microglia, the innate immune cells of the brain, generate a toxic inflammatory response that accelerates synaptic and neuronal injury. Many pro-inflammatory signaling pathways are linked to progression of neurodegeneration. However, endogenous anti-inflammatory pathways capable of suppressing A-induced inflammation represent a relatively unexplored area.
Suppression of Alzheimer-associated inflammation by microglial prostaglandin-E2 EP4 receptor signaling.
Specimen part
View SamplesRecent studies have identified intracellular metabolism as a fundamental determinant of macrophage function. In obesity, proinflammatory macrophages accumulate in adipose tissue and trigger chronic low-grade inflammation, that promotes the development of systemic insulin resistance, yet changes in their intracellular energy metabolism are currently unknown. We therefore set out to study metabolic signatures of adipose tissue macrophages (ATMs) in lean and obese conditions. F4/80-positive ATMs were isolated from obese vs lean mice. High-fat feeding of wild-type mice and myeloid-specific Hif1-/- mice was used to examine the role of hypoxia-inducible factor-1 (HIF-1) in ATMs part of obese adipose tissue. In vitro, bone marrow-derived macrophages were co-cultured with adipose tissue explants to examine adipose tissue-induced changes in macrophage phenotypes. Transcriptome analysis, real-time flux measurements, ELISA and several other approaches were used to determine the metabolic signatures and inflammatory status of macrophages. In addition, various metabolic routes were inhibited to determine their relevance for cytokine production. Transcriptome analysis and extracellular flux measurements of mouse ATMs revealed unique metabolic rewiring in obesity characterised by both increased glycolysis and oxidative phosphorylation. Similar metabolic activation of CD14+ cells in obese individuals was associated with diabetes outcome. These changes were not observed in peritoneal macrophages from obese vs lean mice and did not resemble metabolic rewiring in M1-primed macrophages. Instead, metabolic activation of macrophages was dose-dependently induced by a set of adipose tissue-derived factors that could not be reduced to leptin or lactate. Using metabolic inhibitors, we identified various metabolic routes, including fatty acid oxidation, glycolysis and glutaminolysis, that contributed to cytokine release by ATMs in lean adipose tissue. Glycolysis appeared to be the main contributor to the proinflammatory trait of macrophages in obese adipose tissue. HIF-1, a key regulator of glycolysis, nonetheless appeared to play no critical role in proinflammatory activation of ATMs during early stages of obesity. Our results reveal unique metabolic activation of ATMs in obesity that promotes inflammatory cytokine release. Further understanding of metabolic programming in ATMs will most likely lead to novel therapeutic targets to curtail inflammatory responses in obesity.
Unique metabolic activation of adipose tissue macrophages in obesity promotes inflammatory responses.
Sex, Specimen part
View SamplesUncontrolled microglial activation may lead to development of inflammation-induced brain damage. Here we uncover a ribosome-based mechanism/check point involved in control of the innate immune response and microglial activation. Using an in vivo model-system for analysis of the dynamic translational state of microglial ribosomes with mRNAs as input and newly synthesized peptides as an output, we find a marked dissociation of microglia mRNA and protein networks following innate immune challenge. Highly up-regulated and ribosome-associated mRNAs were not translated resulting in two distinct microglial molecular signatures, a highly specialized pro-inflammatory mRNA and immunomodulatory/homeostatic protein signature. We find that this is due to specific translational suppression of highly expressed mRNAs through a 3UTR-mediated mechanism involving the RNA binding protein SRSF3. This discovery suggests avenues for therapeutic modulation of innate immune response in resident microglia.
Diverging mRNA and Protein Networks in Activated Microglia Reveal SRSF3 Suppresses Translation of Highly Upregulated Innate Immune Transcripts.
Treatment
View SamplesNSAIDs (non-steroidal anti-inflammatory drugs) inhibit cyclooxygenase (COX) enzymes and prevent Alzheimers disease (AD) at preclinical stages in cognitively normal aging populations. We modeled NSAID prevention of memory impairment in AD model mice to identify novel targets of NSAID action.
Cyclooxygenase inhibition targets neurons to prevent early behavioural decline in Alzheimer's disease model mice.
Age, Specimen part, Treatment
View SamplesMolecular mechanisms that are responsible for the development of human skin epithelial cells are not completely understood so far. As a consequence, the efficiency to establish a pure skin epithelial cell population from human induced pluripotent stem cells (hiPSC) remains poor. Using an approach including RNA interference and high-throughput imaging of early epithelial cells, we could identify candidate kinases which are involved in skin epithelial differentiation. Among them, we found HIPK4 to be an important inhibitor of this process. Indeed, its silencing increased the amount of generated skin epithelial precursors, increased the amount of generated keratinocytes and improved growth and differentiation of organotypic cultures, allowing for the formation of a denser basal layer and stratification with the expression of several keratins. Our data bring substantial input in the regulation of human skin epithelial differentiation and for improving differentiation protocols from pluripotent stem cells.
An RNAi Screen Reveals an Essential Role for HIPK4 in Human Skin Epithelial Differentiation from iPSCs.
Specimen part, Time
View SamplesThe size and scope of microarray experiments continue to increase. However, datasets generated on different platforms or at different centres contain biases. Improved techniques are needed to remove platform- and batch-specific biases. One experimental control is the replicate hybridization of a subset of samples at each site or on each platform to learn the relationship between the two platforms. To date, no algorithm exists to specifically use this type of control. LTR is a linear-modelling-based algorithm that learns the relationship between different microarray batches from replicate hybridizations. LTR was tested on a new benchmark dataset of 20 samples hybridized to different Affymetrix microarray platforms. Before LTR, the two platforms were significantly different; application of LTR removed this bias. LTR was tested with six separate data pre-processing algorithms, and its effectiveness was independent of the pre-processing algorithm. Sample-size experiments indicate that just three replicate hybridizations can significantly reduce bias. An R library implementing LTR is available.
LTR: Linear Cross-Platform Integration of Microarray Data.
Sex
View Samplesaffy_rice_2011_03 - affy_compartimentation_rice_albumen_embryon - During germination, the rice seed goes from a dry quiescent state to an active metabolism. As with all cereals, the rice seed is highly differentiated between the embryo (that will give rise to the future plantlet) and the endosperm (that contains the seed storage compounds and that will degenerate). The molecular mechanisms operating in the rice seed embryo have begun to be described. Yet, very few studies have focused specifically on the endosperm during the germination process. In particular, the endosperm is mostly addressed with regards to its storage proteins but we have detected a large protein diversity by two-dimensional electrophoresis. Similarly, the endosperm is rich in total RNA which suggest that gene expression coming from seed maturation could play a role during the germination process. In this context, we want to compare the transcriptome of the embryo and the endosperm during rice seed germination. -We germinate rice seeds of the first sequenced rice cultivar i.e. Nipponbare during 0, 4, 8, 12, 16 and 24h of imbibition in sterile distilled water. Germination occurs under constant air bubbling, in the dark at 30C. These rice seeds are then manually dissected into embryo and endosperm fractions. -The embryo-derived samples are abbreviated in E while the endosperm samples are abbreviated A. The germination time-point is indicated after the letter (e.g. E8 for embryo samples harvested after 8 hours of germination). Finally, the biological repetition number is indicated before the letter and the time digit (e.g. 1-E8 for an embryo sample from the first repetition at 8 hours of imbibition).
Compartmentation and dynamics of flavone metabolism in dry and germinated rice seeds.
Specimen part
View SamplesANGPTL4 regulates plasma lipids, making it an attractive target for correcting dyslipidemia. However, ANGPTL4 inactivation in mice fed a high fat diet causes chylous ascites, an acute-phase response, and mesenteric lymphadenopathy. Here, we studied the role of ANGPTL4 in lipid uptake in macrophages and in the above-mentioned pathologies using Angptl4-hypomorphic and Angptl4-/- mice. Angptl4 expression in peritoneal and bone marrow-derived macrophages was highly induced by lipids. Recombinant ANGPTL4 decreased lipid uptake in macrophages, whereas deficiency of ANGPTL4 increased lipid uptake, upregulated lipid-induced genes, and increased respiration. ANGPTL4 deficiency did not alter LPL protein levels in macrophages. Angptl4-hypomorphic mice with partial expression of a truncated N-terminal ANGPTL4 exhibited reduced fasting plasma triglyceride, cholesterol, and non-esterified fatty acid levels, strongly resembling Angptl4-/- mice. However, during high fat feeding, Angptl4-hypomorphic mice showed markedly delayed and attenuated elevation in plasma serum amyloid A and much milder chylous ascites than Angptl4-/- mice, despite similar abundance of lipid-laden giant cells in mesenteric lymph nodes. In conclusion, ANGPTL4 deficiency increases lipid uptake and respiration in macrophages without affecting LPL protein levels. Compared with the absence of ANGPTL4, low levels of N-terminal ANGPTL4 mitigate the development of chylous ascites and an acute-phase response in mice.
Characterization of ANGPTL4 function in macrophages and adipocytes using <i>Angptl4</i>-knockout and <i>Angptl4</i>-hypomorphic mice.
No sample metadata fields
View SamplesRemoval of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation. Overall design: v6.5 mouse embryonic stem cells were untreated, treated with the Clk kinase inhibitor KH-CB19, or treated with DMSO as a negative control. Untreated cells were harvested and a single replicate was sequenced using a custom, ligation-based, stranded library preparation protocol. Treated cells were harvested at time 0 and at 2 hours post-treatment, and poly(A)-selected RNA-seq libraries were made from biological duplicates for each treatment/time, barcoded, and sequenced by strand-specific, paired-end sequencing using the Illumina TruSeq kit.
Detained introns are a novel, widespread class of post-transcriptionally spliced introns.
No sample metadata fields
View SamplesDeep Sequencing of mRNA from the Drosophila melanogaster cell line D.Mel-2 Overall design: Analysis of poly(A)+ RNA of D.Mel-2 cell line
Design and evaluation of genome-wide libraries for RNA interference screens.
Cell line, Subject
View Samples