Glucose is the most important metabolic substrate of the retina and maintenance of nor-moglycemia is an essential challenge for diabetic patients. Glycemic excursions could lead to cardiovascular disease, nephropathy, neuropathy and retinopathy. We recently showed that hy-poglycemia induced retinal cell death in mouse via caspase 3 activation and glutathione (GSH) decrease. Ex vivo experiments in 661W photoreceptor cells confirmed the low-glucose induction of death via superoxide production and activation of caspase 3, which was concomitant with a decrease of GSH content. We evaluate herein retinal gene expression 4 h and 48 h after insulin-induced hypoglycemia. Microarray analysis demonstrated clusters of genes whose expression is modified by hypoglycemia and we discuss the potential implication of those genes in retinal cell death. In addition, we highlight, by gene set enrichment analysis, three important pathways, including KEGG lysosomes, KEGG GSH metabolism and REACTOME apoptosis pathways. We tested the effect of recurrent hypoglycemia (three successive 5h periods of hypoglycemia separated by 48 h recovery) on retinal cell death. Interestingly, exposure to multiple hypoglycemic events prevents retinal cell death and GSH decrease, or adapts the retina to external stress by restoring GSH level comparable to control situation. We hypothesize that scavenger GSH is a key compound in this apoptotic process, and maintaining normal GSH level, as well as a strict glycemic control, may represent a therapeutic challenge in order to avoid side effects of diabetes, especially diabetic retinopathy.
Biological Characterization of Gene Response to Insulin-Induced Hypoglycemia in Mouse Retina.
Sex, Age, Specimen part
View SamplesThrough post-transcriptional regulation of gene expression, miRNAs affect numerous regulatory pathways including those crucial for maintaining metabolic balance. Here we demonstrate that a neuronal-specific inhibition of miRNA maturation in adult mice leads to a rapid development of severe obesity, which is equally rapidly reversed. Development of obesity was associated with increased food intake and efficiency, and decreased locomotor activity. The ensuing decrease in body weight resembled a catabolic state with lowered O2-consumption and respiratory-exchange ratio. Brain transcriptome analyses in obese mice identified several obesity-related pathways including leptin, somatostatin, and nemo-like kinase signaling, as well as genes involved in feeding and appetite (e.g. Pmch, Neurotensin). A cluster of genes involved in synaptic plasticity was specifically enriched in post-obese mice that did not appear in obese mice. While other studies have identified a role for miRNAs in obesity our model is unique in that it allows for the study of processes involved in reversing obesity.
A neuron-specific deletion of the microRNA-processing enzyme DICER induces severe but transient obesity in mice.
Specimen part, Time
View SamplesWe assessed the impact of glucose transporter Glut2 gene inactivation in adult mouse liver (LG2KO mice). This suppressed hepatic glucose uptake but not glucose output. In the fasted state, expression of carbohydrate responsive element-binding protein (ChREBP) and its glycolytic and lipogenic target genes was abnormally elevated. Feeding, energy expenditure, and insulin sensitivity were identical in LG2KO and control mice. Glucose tolerance was normal early after Glut2 inactivation but intolerance developed at later time. This was caused by progressive impairment of glucose-stimulated insulin secretion even though beta-cell mass and insulin content remained normal. Liver transcript profiling revealed a coordinate down-regulation of cholesterol biosynthesis genes in LG2KO mice. This was associated with reduced hepatic cholesterol in fasted mice and a 30 percent reduction in bile acid production. We showed that chronic bile acids or FXR agonist treatment of primary islets increases glucose-stimulated insulin secretion, an effect not seen in islets from fxr-/- mice. Collectively, our data show that glucose sensing by the liver controls beta-cell glucose competence, through a mechanism that likely depends on bile acid production and action on beta-cells.
Hepatic glucose sensing is required to preserve β cell glucose competence.
Specimen part
View SamplesPdgfra-expressing (Pdgfra+) cells have been implicated as progenitors in many mesenchymal tissues. To further characterize Pdgfra+ cells during alveologensis, we performed single-cell RNA sequencing (scRNA-Seq) analysis using fluorescence-activated cell sorting (FACS) sorted GFP+ cells from Pdgfra-GFP lungs at P7 and P15. Overall design: We perfomed 10X genomics single-cell RNA-seq of Pdgfra-GFP+ cells at P7 and P15
<i>Pdgfra</i> marks a cellular lineage with distinct contributions to myofibroblasts in lung maturation and injury response.
Specimen part, Subject
View SamplesDEAD-box RNA helicases eIF4A and Ded1 are believed to promote translation initiation by resolving mRNA secondary structures that impede ribosome attachment at the mRNA 5' end or subsequent scanning of the 5'UTR, but whether they perform distinct functions or act redundantly in vivo is poorly understood. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling. Despite similar reductions in bulk translation, inactivation of a cold-sensitive Ded1 mutant substantially reduced the TEs of >600 mRNAs, whereas inactivation of a temperature-sensitive eIF4A mutant yielded <40 similarly impaired mRNAs. The broader requirement for Ded1 did not reflect more pervasive secondary structures at low temperature, as inactivation of temperature-sensitive and cold-sensitive ded1 mutants gave highly correlated results. Interestingly, Ded1-dependent mRNAs exhibit greater than average 5'UTR length and propensity for secondary structure, implicating Ded1 in scanning though structured 5' UTRs. Reporter assays confirmed that cap- distal stem-loop insertions increase dependence on Ded1 but not eIF4A for efficient translation. While only a small fraction of mRNAs is strongly dependent on eIF4A, this dependence is significantly correlated with requirements for Ded1 and 5'UTR features characteristic of Ded1- dependent mRNAs. Our findings suggest that Ded1 is critically required to promote scanning through secondary structures within 5'UTRs; and while eIF4A cooperates with Ded1 in this function, it also promotes a step of initiation common to virtually all yeast mRNAs. Overall design: We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling.The study includes 32 samples, comprised of 16 mRNA-Seq samples and 16 ribosome footprint profiling samples, derived from biological replicates of 3 mutant strains, ded1-cs, ded1-ts and tif1-ts, and the corresponding wild-type strains. The tif1-ts mutant and its wild-type counterpart were analyzed at 30°C and 37°C.
Functional interplay between DEAD-box RNA helicases Ded1 and Dbp1 in preinitiation complex attachment and scanning on structured mRNAs in vivo.
Subject
View SamplesTo estimate mRNA steady-state levels we used RNA extracted from logarithmically growing fisson yeast cells on Affymetrix Yeast 2.0 Genechip arrays. The signal intensities from two independent biological repeats were averaged, resulting in measurements for 4818 out of 4962 nuclear protein-coding genes.
A network of multiple regulatory layers shapes gene expression in fission yeast.
Sex, Subject
View SamplesMicroarray analysis obtained from RNA of AML12 cells stably expresing Zfp125 or empty vector (EV)
The Foxo1-Inducible Transcriptional Repressor Zfp125 Causes Hepatic Steatosis and Hypercholesterolemia.
Specimen part, Cell line
View SamplesThe aim of this study was to identify differential gene and protein expression associated with GBV-C that may be of importance in reduction of HCV-related liver disease. GB virus C (GBV-C) infection leads to improved outcomes in human immunodeficiency virus (HIV) infection. Furthermore, GBV-C has been shown to reduce hepatitis C virus (HCV)-related liver disease in HCV/HIV co-infection.
Down-regulation of intra-hepatic T-cell signaling associated with GB virus C in a HCV/HIV co-infected group with reduced liver disease.
Sex, Specimen part
View SamplesThe goal of this study was to define relationships between peripheral blood miRNAs and mRNAs of women undergoing idiopathic preterm labor (PTL) and compare network level changes to control women that deliver at term.Using RNA Sequencing we have performed global miRNA and mRNA profiling in both monocytes and whole blood leukocytes of women who underwent PTL (N=15) matched to non-pathological controls (N=30) as a part of the Ontario Birth Study cohort. We have identified differentially expressed miRNAs, mRNAs and pathways associated with PTL. Intriguingly, we found perturbations in many cellular signaling pathways, particularly in interleukin signaling. We also predicted mRNA targets for specific miRNAs and used these predictions to build putative miRNA-mRNA networks. We identified 6 miRNAs significantly associated with PTL whose expression is negatively correlated with expression of 14 predicted mRNA targets that are also significantly associated with PTL. Overall design: miRNA and mRNA were quantified from whole blood and monocytes of women undergoing spontaneous preterm labor compared to nonlabor controls matched on gestational age
Comparative analysis of gene expression in maternal peripheral blood and monocytes during spontaneous preterm labor.
Subject
View SamplesBACKGROUND & AIMS:
Combined Activities of JNK1 and JNK2 in Hepatocytes Protect Against Toxic Liver Injury.
Sex, Specimen part
View Samples