Dysregulation of ceramide synthesis has been associated with metabolic disorders such as atherosclerosis and diabetes mellitus. Using a human hepatoma cell line (Huh7), we investigated the changes in lipid homeostasis and gene expression when the synthesis of ceramide is perturbed by knocking down serine transferases subunits 1, 2 and 3 (SPTLC123) or dihydroceramide desaturase (DEGS1). While the inhibition of serine palmitoyl transferase (SPTLC) affects ceramide production differently at the subspecies level depending upon which SPTLC subunit is silenced; depleting DEGS1 is sufficient to produce a similar outcome as knocking down all SPTLC subunits. Both the distribution of multiple lipid classes, especially at the subspecies level, and the global transcriptional profile is altered differently when either SPTLC123 or DEGS1 were silenced. The overall transcriptional changes indicate a negative regulation in biosynthetic processes and a down-regulation of genes involved in general endomembrane trafficking for both DEGS1 and SPTLC123 siRNA treated cells, but also the up-regulation of genes involved with cell migration function in DEGS1 siRNA cells. Pathway analysis indicate changes in amino acid, sugar and nucleotide metabolisms as well as vesicle trafficking between organelles occurred more robustly in DEGS1 silenced cells. Although either SPTLC123 or DEGS1 siRNA treatment positively regulated numerous genes involved with endocytosis and endosomal recycling, depleting SPTLC123 caused transcriptional changes in genes primarily involved with lipid metabolism. The alterations reflect how SPTLC or DEGS1 silenced cells respond differently to disruption in lipid flux, but also maintain cellular lipid pools through increasing endocytotic processes and down-regulating metabolic biosynthesis without developing endoplasmic reticulum stress. Also, these results are the first to demonstrate that reducing ceramide synthesis by decreasing the function of either SPTLC or DEGS1 affects cellular function differently at the level of lipid synthesis and gene expression.
Silencing of enzymes involved in ceramide biosynthesis causes distinct global alterations of lipid homeostasis and gene expression.
Cell line
View SamplesThere are an estimated 21million diabetics in the United States and 150 million diabetics worldwide. The World Health Organization anticipates that these numbers will double in the next 20 years. Metabolic syndrome is a well recognized set of symptoms that increases a patients risk of developing diabetes. Insulin resistance is a factor in both metabolic syndrome and Type 2 diabetes. It is characterized by decreased insulin stimulated glucose uptake in peripheral tissues, decreased adiponectin levels, increased adipocyte FFA and cytokine production, and increased insulin and hepatic glucose output. Prevention or reversal of insulin resistance should serve as an important strategy in addressing the growing health concerns posed by the Diabetes epidemic. While increased adiposity is associated with insulin resistance, the role of the cell types present within adipose (adipocytes, pre-adipocytes, endothelial cells, macrophages, fibroblasts, leukocytes and smooth muscle cells) in insulin resistance is unclear. In an effort to begin dissection of this question, we examined the transcriptional response of the buoyant and non-buoyant fractions isolated from insulin sensitive or TNF induced insulin resistant hMSC derived adipocytes before and after treatment with insulin.
Genome-wide profiling of H3K56 acetylation and transcription factor binding sites in human adipocytes.
Specimen part
View SamplesPseudomonas fluorescens strain SS101 (Pf.SS101) promotes growth of Arabidopsis thaliana, enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). Here, targeted and untargeted approaches were adopted to identify bacterial determinants and underlying mechanisms involved in plant growth promotion and ISR by Pf.SS101. Based on targeted analyses, no evidence was found for volatiles, lipopeptides and siderophores in plant growth promotion by Pf.SS101. Untargeted, genome-wide analyses of 7,488 random transposon mutants of Pf.SS101 led to the identification of 21 mutants defective in both plant growth promotion and ISR. Many of these mutants, however, were auxotrophic and impaired in root colonization. Genetic analysis of three mutants followed by site-directed mutagenesis, genetic complementation and plant bioassays revealed the involvement of the phosphogluconate dehydratase gene edd, the response regulator gene colR and the adenylsulfate reductase gene cysH in both plant growth promotion and ISR. Subsequent comparative plant transcriptomics analyses strongly suggest that modulation of sulfur assimilation, auxin biosynthesis and transport, steroid biosynthesis and carbohydrate metabolism in Arabidopsis are key mechanisms linked to growth promotion and ISR by Pf.SS101.
Genome-wide analysis of bacterial determinants of plant growth promotion and induced systemic resistance by Pseudomonas fluorescens.
Specimen part, Treatment
View SamplesWe sought to ascertain the time-course of transcriptional events that occur in human skeletal muscle at the outset of resistance exercise (RE) training in RE nave individuals, and determine if the magnitude of any response was associated with exercise induced muscle damage. Sixteen RE nave males were recruited, 8 underwent 2 sessions of 5x30 maximum, isokinetic knee extensions (180.s-1) separated by 48 hrs. Muscle biopsies of the vastus lateralis were taken at baseline and 24 hrs after each exercise bout. Eight individuals acted as non-exercise controls with biopsies obtained at the same time intervals. Transcriptional changes were assessed by microarray, and binding of HSP27 and B-crystallin to insoluble proteins by immunohistochemistry as a measure of muscle damage. In control subjects, no probesets were significantly altered (FDR<0.05) and HSP27 and B-crystallin binding remained unchanged throughout the study. In exercised subjects, significant inter-subject variability following the initial bout of RE was observed in the muscle transcriptome, with greatest changes occurring when HSP27 and B-crystallin binding was elevated. Following the second bout of RE, the transcriptome response was more consistent among subjects revealing a cohort of probesets associated with immune activation, the suppression of oxidative metabolism and protein ubiquitination as differentially regulated. The results reveal that the initial transcriptional response to RE is highly variable in RE nave volunteers, is associated with muscle damage, and unlikely to reflect longer-term adaptations to RE training. These results highlight the importance of considering multiple time-points when determining the transcriptional response to RE and associated physiological adaptation.
Transient transcriptional events in human skeletal muscle at the outset of concentric resistance exercise training.
Sex, Specimen part, Subject, Time
View SamplesAdipose tissue-derived stromal stem cells (ASCs) represent a promising regenerative resource for soft tissue reconstruction. To understand the changes in cell function during the transition of ASCs into fully mature fat cells, we compared the transcriptome profiles of cultured undifferentiated human primary ASCs under conditions leading to acquisition of a mature adipocyte phenotype by microarray analysis.
Expression analysis of human adipose-derived stem cells during in vitro differentiation to an adipocyte lineage.
Sex, Specimen part
View SamplesInhibition of phosphodiesterase 10A (PDE10A) promotes cyclic nucleotide signaling, increases striatal activation, and decreases behavioral activity. Enhanced cyclic nucleotide signaling is a well established route to producing changes in gene expression. We hypothesized that chronic suppression of PDE10A activity would have significant effects on gene expression in the striatum. A comparison of the expression profile of PDE10A knockout (KO) mice and wild-type mice after chronic PDE10A inhibition revealed altered expression of 19 overlapping genes with few significant changes outside the striatum or after administration of a PDE10A inhibitor to KO animals. Chronic inhibition of PDE10A produced up-regulation of mRNAs encoding genes that included prodynorphin, synaptotagmin10, phosphodiesterase 1C, glutamate decarboxylase 1, and diacylglycerol O-acyltransferase and a down-regulation of mRNAs encoding choline acetyltransferase and Kv1.6, suggesting long-term suppression of the PDE10A enzyme is consistent with altered striatal excitability and potential utility as a antipsychotic therapy. In addition, up-regulation of mRNAs encoding histone 3 (H3) and down-regulation of histone deacetylase 4, follistatin, and claspin mRNAs suggests activation of molecular cascades capable of neuroprotection. We used lentiviral delivery of cAMP response element (CRE)-luciferase reporter constructs into the striatum and live animal imaging of 2-{4-[-pyridin-4-yl-1-(2,2,2-trifluoro-ethyl)-1H-pyrazol-3-yl]-phenoxymethyl}-quinoline succinic acid (TP-10)-induced luciferase activity to further demonstrate PDE10 inhibition results in CRE-mediated transcription. Consistent with potential neuroprotective cascades, we also demonstrate phosphorylation of mitogen- and stress-activated kinase 1 and H3 in vivo after TP-10 treatment. The observed changes in signaling and gene expression are predicted to provide neuroprotective effects in models of Huntington's disease.
Chronic suppression of phosphodiesterase 10A alters striatal expression of genes responsible for neurotransmitter synthesis, neurotransmission, and signaling pathways implicated in Huntington's disease.
Specimen part, Treatment
View SamplesThe epidemic character of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), especially the geographically widespread clone USA300, is poorly understood. USA300 isolates carry a type IV staphylococcal chromosomal cassette mec (SCCmec) element conferring -lactam antibiotic class resistance and a putative pathogenicity island, ACME (arginine catabolic mobile element).
The arginine catabolic mobile element and staphylococcal chromosomal cassette mec linkage: convergence of virulence and resistance in the USA300 clone of methicillin-resistant Staphylococcus aureus.
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View SamplesStudy the role of klotho as a tumor suppressor in colorectal cancer.
Klotho suppresses colorectal cancer through modulation of the unfolded protein response.
Cell line
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