Rare heterozygous coding variants in the triggering receptor expressed in myeloid cells 2 (TREM2) gene, conferring increased risk of developing late-onset Alzheimer''s disease, have been identified. We examined the transcriptional consequences of the loss of Trem2 in mouse brain to better understand its role in disease using differential expression and coexpression network analysis of Trem2 knockout and wild-type mice. We generated RNA-Seq data from cortex and hippocampus sampled at 4 and 8 months. Using brain cell-type markers and ontology enrichment, we found subnetworks with cell type and/or functional identity. We primarily discovered changes in an endothelial gene-enriched subnetwork at 4 months, including a shift toward a more central role for the amyloid precursor protein gene, coupled with widespread disruption of other cell-type subnetworks, including a subnetwork with neuronal identity. We reveal an unexpected potential role of Trem2 in the homeostasis of endothelial cells that goes beyond its known functions as a microglial receptor and signaling hub, suggesting an underlying link between immune response and vascular disease in dementia. Methods: We performed differential expression and co-expression network analysis on a RNA-Seq profiled Trem2 knockout (KO) mouse using two brain areas sampled at 4- and 8-months to obtain a systems level view of the effects of the absence of Trem2. Results: The absence of Trem2 has a stronger effect at an earlier age with the number of differential expressed (DE) genes being 17-fold greater at 4 months than at 8 months in cortex. By integrating DE genes and network analysis, we discovered gene clusters associated with the disruption of blood vessel formation at 4 months of age and protein targeting primarily affecting the hippocampus at 8 months. Further integration of cell type and ontology information revealed a large disruption of a gene module enriched for endothelial cell markers coinciding with the module enriched for neuron cell markers having weaker connections to modules with oligodendrocyte and astrocyte identities. The module with neuronal identity has decreased expression only in the KO where it has closer association with a new module enriched for phagocytic functions. Conclusions: Combining gene co-expression and differential expression analysis on a newly generated RNA-Seq profiled Trem2 KO mouse demonstrate that the absence of Trem2 produces a disruption which mainly affects endothelialon related processes at 4 months of age. It results in a ripple effect that disrupts the cross-talk of other cell types at 8 months, including reduced expression of a gene module enriched in neuron related functions and a shift towards a more central role for App. This study reveals an unexpected role of Trem2 in the homeostasis of endothelial cells that goes beyond its known functions as a microglial receptor and signaling hub suggesting new paths for investigation at the intersection between Trem2, Alzheimer's disease and vascular dementia. Overall design: Hippocampus and cortex were selected because they represent tissues affected in AD at early and late stages, respectively (Matarin 2015, Mastrangelo 2008). Brain tissue samples were obtained from male Trem2 knockout (KO) and wild type (WT) control mice at two time points: 4 months and 8 months. These time points span the onset and late disease stages in well established AD mouse models (Matarin 2015). RNA-Seq was used to profile the transcriptomes for each sample. Two technical replicates were obtained for each sample.
Loss of Trem2 in microglia leads to widespread disruption of cell coexpression networks in mouse brain.
Sex, Specimen part, Subject
View SamplesAberrant activation of the Akt pathway has been implicated in several human pathologies including cancer. However, current knowledge on the involvement of Akt signaling in development is limited. Previous data have suggested that Akt-mediated signaling may be an essential mediator of epidermal homeostasis through cell autonomous and non-cell autonomous mechanisms. Here we report the developmental consequences of deregulated Akt activity in the basal layer of stratified epithelia, mediated by the expression of a constitutively active Akt1
Constitutively active Akt induces ectodermal defects and impaired bone morphogenetic protein signaling.
Age, Specimen part
View SamplesDevelopment of a suitable mouse model would facilitate the investigation of pathomechanisms underlying human psoriasis and would also assist in development of therapeutic treatments. However, while many psoriasis mouse models have been proposed, no single model recapitulates all features of the human disease, and standardized validation criteria for psoriasis mouse models have not been widely applied. In this study, whole-genome transcriptional profiling is used to compare gene expression patterns manifested by human psoriatic skin lesions with those that occur in five psoriasis mouse models (K5-Tie2, imiquimod, K14-AREG, K5-Stat3C and K5-TGFbeta1). While the cutaneous gene expression profiles associated with each mouse phenotype exhibited statistically significant similarity to the expression profile of psoriasis in humans, each model displayed distinctive sets of similarities and differences in comparison to human psoriasis. For all five models, correspondence to the human disease was strong with respect to genes involved in epidermal development and keratinization. Immune and inflammation-associated gene expression, in contrast, was more variable between models as compared to the human disease. These findings support the value of all five models as research tools, each with identifiable areas of convergence to and divergence from the human disease. Additionally, the approach used in this paper provides an objective and quantitative method for evaluation of proposed mouse models of psoriasis, which can be strategically applied in future studies to score strengths of mouse phenotypes relative to specific aspects of human psoriasis.
Genome-wide expression profiling of five mouse models identifies similarities and differences with human psoriasis.
Specimen part
View SamplesIgE plays an essential role in the pathogenesis of allergies and its production is strongly regulated. A transient IgE germinal center phase and lack of IgE memory cells limit the generation of pathogenic IgE, but this can be overcome by sequential switching of IgG1 cells to IgE. We investigated which population of IgG1 cells can give rise to IgE-producing cells in memory responses. We identified three populations of IgG1 memory B cells (DP:CD73+CD80+, SP:CD73-CD80+, DN:CD73-CD80-) that generate IgE plasma cells of high or low affinity, but none gives rise to IgE germinal center cells or IgE memory cells. The two memory IgG1 populations differ however in their ability to differentiate into IgG1 plasma cells and germinal center cells, and to expand the IgG1 memory B cell pool. To explore the molecular mechanisms that may explain the distinct functions of IgG1 memory B cell subsets we compared their expression by transcriptome analysis using next generation sequencing. Overall design: mRNA profiles of quadruplicates of double positive (DP:CD73+CD80+), single positive (SP:CD73-CD80+), double negative (DN:CD73-CD80-) IgG1 memory B cells along with IgG1 germinal center (GC) cells and naïve B cells were generated using Illumina high throughput sequencing.
IgG1 memory B cells keep the memory of IgE responses.
Specimen part, Cell line, Subject
View SamplesDifferential gene expression between groups of homogenous cell types is a biological question whose time has come. RNA can be extracted from small numbers of cells, such as those isolated by laser capture microdissection, but the small amounts obtained often require amplification to enable whole genome transcriptome profiling by technologies such as microarray analysis and RNA-seq. Recently, advances in amplification procedures make amplification directly from whole cell lysates possible. The aim of this study was to compare two amplification systems for variations in observed RNA abundance attributable to the amplification procedure for use with small quantities of cells isolated by laser capture microdissection. Arabidopsis root cells undergoing giant cell formation due to nematode infestation and un-infested control root cells were laser captured and used to evaluate 2 amplification systems. One, NuGEN's WT-Ovation Pico amplification system, uses total RNA as starting material while the other, NuGEN's WT-One-Direct Amplification system, uses lysate containing the captured cells. The reproducibility of whole genome transcript profiling and correlations of both systems were investigated after microarray analysis. The NuGEN WT-Ovation One-Direct system was less reproducible and more variable than the NuGEN WT-Ovation Pico system. The NuGEN WT-Ovation Pico Amplification kit resulted in the detection of thousands of genes differentially expressed genes between giant cells and control cells. This is in marked contrast to the relatively few genes detected after amplification with the NuGEN WT-Ovation One-Direct Amplification kit.
Comparison between NuGEN's WT-Ovation Pico and one-direct amplification systems.
Specimen part, Time
View SamplesUntreated HIV-1 infection progresses through acute and asymptomatic stages to AIDS. While each of the three stages has well-known clinical, virologic and immunological characteristics, much less is known of the molecular mechanisms underlying each stage. Here we report lymphatic tissue microarray analyses revealing for the first time stage-specific patterns of gene expression during HIV-1 infection. We show that while there is a common set of key genes with altered expression throughout all stages, each stage has a unique gene-expression signature. The acute stage is most notably characterized by increased expression of hundreds of genes involved in immune activation, innate immune defenses (e.g.MDA-5, TLR-7 and -8, PKR, APOBEC3B, 3F, 3G), adaptive immunity, and in the pro-apoptotic Fas-Fas-L pathway. Yet, quite strikingly, the expression of nearly all acute-stage genes return to baseline levels in the asymptomatic stage, accompanying partial control of infection. In the AIDS stage, decreased expression of numerous genes involved in T cell signaling identifies genes contributing to T cell dysfunction. These common and stage-specific, gene-expression signatures provide new insights into the molecular mechanisms underlying the host response and the slow, natural course of HIV-1 infection.
Microarray analysis of lymphatic tissue reveals stage-specific, gene expression signatures in HIV-1 infection.
Sex, Age, Specimen part, Disease, Disease stage, Race, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
BIM upregulation and ROS-dependent necroptosis mediate the antitumor effects of the HDACi Givinostat and Sorafenib in Hodgkin lymphoma cell line xenografts.
Specimen part, Cell line, Treatment
View SamplesThe chemokine decoy receptor D6 internalises and degrades inflammatory CC chemokines enabling resolution of inflammation. In D6 deficient mice (D6 KO), otherwise innocuous cutaneous inflammatory stimuli induce a grossly exaggerated inflammatory response that bears many similarities to human psoriasis. In the present study we have used transcriptomic approaches to define the molecular make up of this response.
Microarray analyses demonstrate the involvement of type I interferons in psoriasiform pathology development in D6-deficient mice.
Sex, Specimen part, Treatment, Time
View SamplesRelapsed/refractory Hodgkin lymphoma (HL) is an unmet medical need requiring new therapeutic options. Interactions between the histone deacetylase inhibitor Givinostat and the RAF/MEK/ERK inhibitor Sorafenib were examined in HDLM-2 and L-540 HL cell lines. Exposure to Givinostat/Sorafenib induced a synergistic inhibition of cell growth (range, 70- 80%) and a dramatic increase in cell death (up to 96%) due to increased H3 and H4 acetylation and strong mitochondrial injury. Gene expression profiling indicated that the synergistic effects of Givinostat/Sorafenib treatment are associated with the modulation of cell cycle and cell death pathways. Exposure to Givinostat/Sorafenib resulted in sustained production of reactive oxygen species (ROS) and activation of necroptotic cell death. The necroptosis inhibitor Necrostatin-1 prevented Givinostat/Sorafenib-induced ROS production, mitochondrial injury, activation of BH3-only protein BIM and cell death. Knockdown experiments identified BIM as a key signaling molecule that mediates Givinostat/Sorafenib-induced oxidative death of HL cells. Furthermore, in vivo xenograft studies demonstrated a 50% reduction in tumor burden (P < 0.0001), a 5- to 15-fold increase in BIM expression (P .0001) and a 4-fold increase in tumor necrosis in Givinostat/Sorafenib-treated animals compared to mice that received the single agents. These results provide a rationale for exploring Givinostat/Sorafenib combination in relapsed/refractory HL.
BIM upregulation and ROS-dependent necroptosis mediate the antitumor effects of the HDACi Givinostat and Sorafenib in Hodgkin lymphoma cell line xenografts.
Cell line, Treatment
View SamplesRelapsed/refractory Hodgkin lymphoma (HL) is an unmet medical need requiring new therapeutic options. Interactions between the histone deacetylase inhibitor Givinostat and the RAF/MEK/ERK inhibitor Sorafenib were examined in HDLM-2 and L-540 HL cell lines. Exposure to Givinostat/Sorafenib induced a synergistic inhibition of cell growth (range, 70- 80%) and a dramatic increase in cell death (up to 96%) due to increased H3 and H4 acetylation and strong mitochondrial injury. Gene expression profiling indicated that the synergistic effects of Givinostat/Sorafenib treatment are associated with the modulation of cell cycle and cell death pathways. Exposure to Givinostat/Sorafenib resulted in sustained production of reactive oxygen species (ROS) and activation of necroptotic cell death. The necroptosis inhibitor Necrostatin-1 prevented Givinostat/Sorafenib-induced ROS production, mitochondrial injury, activation of BH3-only protein BIM and cell death. Knockdown experiments identified BIM as a key signaling molecule that mediates Givinostat/Sorafenib-induced oxidative death of HL cells. Furthermore, in vivo xenograft studies demonstrated a 50% reduction in tumor burden (P < 0.0001), a 5- to 15-fold increase in BIM expression (P .0001) and a 4-fold increase in tumor necrosis in Givinostat/Sorafenib-treated animals compared to mice that received the single agents. These results provide a rationale for exploring Givinostat/Sorafenib combination in relapsed/refractory HL.
BIM upregulation and ROS-dependent necroptosis mediate the antitumor effects of the HDACi Givinostat and Sorafenib in Hodgkin lymphoma cell line xenografts.
Cell line, Treatment
View Samples