Transcriptional fingerprint of hypomyelination in Zfp191null and Shiverer (Mbpshi) mice
Transcriptional Fingerprint of Hypomyelination in Zfp191null and Shiverer (Mbpshi) Mice.
Sex, Specimen part, Cell line
View SamplesOligodendrocytes (OLs) and myelin are critical for normal brain function and they have been implicated in neurodegeneration. Human neuroimaging studies have demonstrated that alterations in axons and myelin occur early in Alzheimer's Disease (AD) course. However, the molecular mechanism underlying the role of OLs in AD remains largely unknown. In this study, we systematically interrogated OL-enriched gene networks constructed from large-scale genomic, transcriptomic, and proteomic data in human AD postmortem brain samples. These robust OL networks were highly enriched for genes associated with AD risk variants, including BIN1. We corroborated the structure of the AD OL coexpression and gene-gene interaction networks through ablation of genes identified as key drivers of the networks, including UGT8, CNP, MYRF, PLP1, NPC1, and NDGR1. Perturbations of these key drivers not only caused dysregulation in their associated network neighborhoods, but also mimicked pathways of gene expression dysregulation seen in human AD postmortem brain samples. In particular, the OL subnetwork controlled by the AD risk gene PSEN1 was strongly dysregulated in AD, suggesting a potential role of PSEN1 in disrupting the myelination pathway towards the onset of AD. In summary, this study built and systematically validated the first comprehensive molecular blueprint of OL dysregulation in AD, and identified key OL- and myelination-related genes and networks as potential candidate targets for the future development of AD therapies. Overall design: The mouse knockout models have been previously described for each of Ugt8 (Coetzee et al., 1996), Cnp (Lappe-Siefke et al., 2003), and Plp1 (Klugmann et al., 1997). For each of the two conditions studied (control and homozygous knockout mice), five mice of either sex were sacrificed at postnatal day 20 and brains were flashed-frozen until analysis. The frontal cortex (FC) and cerebellum (CBM) were dissected out and individually processed. RNA was isolated using Trizol reagent and processed using Ribo-Zero rRNA removal. RNA-sequencing was performed using the Illumina HiSeq2000 with 100 nucleotide paired-end reads. RNA-sequencing reads were mapped to the mouse genome (mm10, UCSC assembly) using Bowtie (version 2.2.3.0), TopHat (version 2.0.11), and SamTools (version 0.1.19.0) using a read length of 100. Reads were converted to counts at the gene level using HTSeq on the BAM files from TopHat2 using the UCSC known genes data set.
Multiscale network modeling of oligodendrocytes reveals molecular components of myelin dysregulation in Alzheimer's disease.
Specimen part, Subject
View SamplesThe two vertebrate Gsk-3 isoforms, Gsk-3a and Gsk-3b, are encoded by distinct genetic loci and exhibit mostly redundant function in murine embryonic stem cells (ESCs). Here we report that deletion of both Gsk-3a and Gsk-3b in mouse ESCs results in misregulated expression of imprinted genes and hypomethylation of corresponding imprinted loci. Treatment of wild-type ESCs with small molecule inhibitors of Gsk-3 phenocopies the DNA hypomethylation of imprinted loci observed in Gsk-3 null ESCs. We provide evidence that DNA hypomethylation in Gsk-3 null ESCs is due to a reduction in the levels of the de novo DNA methyltransferase, Dnmt3a2.
Phosphatidylinositol 3-kinase (PI3K) signaling via glycogen synthase kinase-3 (Gsk-3) regulates DNA methylation of imprinted loci.
Specimen part
View SamplesThe role of RB1 in response to radiation was examined in human osteoblasts. We demonstrate that RB1 induced SASP genes, a response which was attenuated in RB1 knockdown osteoblasts.
Immune response to RB1-regulated senescence limits radiation-induced osteosarcoma formation.
Specimen part, Cell line
View SamplesDamage to and/or loss of sensory neurons can result in debilitating neuropathies that often have a dramatic impact on quality of life. The cellular mechanisms involved in the response of neurons and glia to such pathological insults are poorly understood. Investigation has shown that peripheral glia play critical roles in both the degenerative and regenerative processes that are involved in the responses to peripheral nerve damage. The vast majority of studies have focused primarily on myelinating Schwann cells], with the result that very little is known regarding how the non-myelinating glia that ensheath axons and neuronal somas respond to nerve damage. This is a significant knowledge gap, given that over 80% of cutaneous fibers are unmyelinated, that they transduce such important modalities as itch, pain, temperature, touch and pressure, and that they are affected in many prevalent peripheral neuropathies. It is the goal of this study to shed light on the genetic programs involved in the responses of non-myelinating glia roles to nerve degeneration. We utilized RNA-seq to identify genes that were differentially expressed in the larval head during the process of sensory neuron ablation and axon degeneration in both wild-type larvae and in larvae that do not have peripheral glia (foxd3 mutants) using a selective, conditional approach. Overall, the information regarding differential gene expression in these conditions will provide a basis for further investigation into the cellular processes that underlie pathophysiological responses of neurons and glia to sensory nerve damage. Overall design: mRNA levels were determined using biological triplicate samples from five sets of samples. Three sets from wild-type: control, 2 hrs of metronidazole treatment and 5 hrs of metronidazole treatment. And two sets from foxd3 mutants: control and 5hrs of metronidazole treatment.
Transcriptome Analysis of Chemically-Induced Sensory Neuron Ablation in Zebrafish.
No sample metadata fields
View SamplesTienilic acid (TA) was withdrawn from the US market due to numerous cases of liver necrosis. Two major hypotheses currently used to understand the mechanisms of idiosyncratic reactions such as TA-induced hepatotoxicity are the hapten and danger hypotheses. Both human cytochrome (CYP) P450 2C9 and the rat ortholog CYP 2C11 metabolize TA, and it was reported that a reactive metabolite of TA binds almost exclusively to these enzymes, thus acting as a mechanism-based inhibitor. TA-induced liver toxicity is associated with antibodies against CYP 2C9, thus TA appears to act as a hapten. However, if the binding were limited to CYP 2C, it is unlikely that this would lead to significant cell stress. Thus, if TA does not cause cell stress it would suggest that a drug does not have to generate a danger signal in order to cause an idiosyncratic drug reaction and acting as a hapten is sufficient. In order to test whether TA can cause cell stress, male Sprague Dawley rats were orally dosed with TA, and hepatic gene expression was profiled at 6 and 24 h after drug administration.
Changes in gene expression induced by tienilic Acid and sulfamethoxazole: testing the danger hypothesis.
No sample metadata fields
View SamplesExpression analysis of 36 pancreatic ductal adenocarcinoma tumors and matching normal pancreatic tissue samples from pancreatic cancer patients of the Clinical Institute Fundeni (ICF) using Affymetrix U133 Plus 2.0 whole-genome chips.
Combined gene expression analysis of whole-tissue and microdissected pancreatic ductal adenocarcinoma identifies genes specifically overexpressed in tumor epithelia.
Subject
View SamplesAlzheimer's disease (AD) is a devastating neurodegenerative disorder that threatens to reach epidemic proportions as our population ages. Although much research has examined molecular pathways associated with AD, relatively few studies have focused on critical early stages. Our prior microarray study correlated gene expression in human hippocampus with AD markers. Results suggested a new model of early-stage AD in which pathology spreads along myelinated axons, orchestrated by upregulated transcription and epigenetic factors related to growth and tumor suppression (Blalock et al., 2004). However, the microarray analyses were performed on RNA from fresh frozen hippocampal tissue blocks containing both gray and white matter, potentially obscuring region-specific changes. In the present study, we used laser capture microdissection to exclude major white matter tracts and selectively collect CA1 hippocampal gray matter from formalin-fixed, paraffin-embedded (FFPE) hippoc ampal sections of the same subjects assessed in our prior study. Microarray analyses of this gray matter-enriched tissue revealed many correlations similar to those seen in our prior study, particularly for neuron-related genes. Nonetheless, in the laser-captured tissue, we found a striking paucity of the AD-associated epigenetic and transcription factor genes that had been strongly overrepresented in the prior tissue block study. In addition, we identified novel pathway alterations that may have considerable mechanistic implications, including downregulation of genes stabilizing ryanodine receptor Ca2+ release and upregulation of vascular development genes. We conclude that FFPE tissue can be a reliable resource for microarray studies, that upregulation of growth-related epigenetic/ transcription factors with incipient AD is predominantly localized to white matter, further supporting our prior findings and model, and that alterations in vascular and ryanodine receptor-relat ed pathways in gray matter are closely associated with incipient AD.
Microarray analyses of laser-captured hippocampus reveal distinct gray and white matter signatures associated with incipient Alzheimer's disease.
Sex, Age, Disease
View SamplesMacrophages play a critical role in the pathogenesis of many diseases, including rheumatoid arthritis, inflammatory bowel disease and atherosclerosis. Monocytes recruited into tissues from peripheral blood differentiate into macrophages. There is limited data concerning the global changes in the expression of genes during monocyte to macrophage, and how the patterns of change identify the mechanism contributing to differentiation or macrophage function. Employing the microarray technology, we examined the transcriptional profile of in vitro adherence-induced differentiation of primary human monocytes into macrophages. We found the significant up regulation of genes contributing to the functions of macrophage, including signature patterns defining the induction of genes contributing to immunity and defense; lipid, fatty acid and steroid metabolism; cell adhesion and; carbohydrate metabolism; amino acid metabolism and endocytosis. In contrast, a variety of transcription factors were down regulated during monocyte to macrophage differentiation, suggesting that transcriptional repression may be important for the transition from monocytes to macrophages. However, a limited number of transcription factors were up regulated, among these was C/EBPA, which may contribute to differentiation by regulating down stream genes, which a characteristic of differentiated macrophages. These observations suggest that examination of the transcriptional profile in monocytes and macrophages in patients may identify relevant therapeutic targets in diseases such as rheumatoid arthritis and atherosclerosis.
Transcriptional diversity during monocyte to macrophage differentiation.
No sample metadata fields
View SamplesALTERED MERISTEM PROGRAM1 (AMP1) is a member of the M28 family of carboxypeptidases with a pivotal role in cell fate maintenance in the embryo and shoot meristem. A defect in AMP1 function results in suspensor to embryo conversion and a hypertrophic shoot meristem forming ectopic stem cell pools. However, so far the role of AMP1 in shoot development could not be assigned to a specific molecular pathway nor is its biochemical function resolved. Double mutants in CYP78A5 and CYP78A7 develop a similar set of cell fate defects. To further assess whether this phenotypic overlap is also depicted in a congruency at the global gene expression level, we analyzed the transcriptomic responses of both genotypes
AMP1 and CYP78A5/7 act through a common pathway to govern cell fate maintenance in Arabidopsis thaliana.
Age, Specimen part
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