We 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 SamplesThe Rift Valley Fever (RVF) is an arthropod-borne disease present in several countries of Africa and Middle East. It is caused by RVF virus which can infect both humans and animals. In humans, it leads to various manifestations including hepatitis, encephalitis and death, while in domestic animals it usually causes miscarriage in pregnant females and it is often fatal for the newborn. Not all people or animal infected by the virus present the same disease. Some patients exhibit unapparent or moderate febrile reactions, while others develop severe symptoms. This observation suggests that host genetic factors play a role in controlling the outcome of infection. In this work, we compare the response of two different inbred strains of mice, MBT/Pas and BALB/cByJ, to infection with RVF virus. These strains exhibit different profiles of susceptibility to RVF virus infection. Indeed, MBT/Pas mice rapidly develop high viraemia and die soon after infection, while BALB/cByJ mice have a lower viraemia and die later. Interestingly, mouse embryonic fibroblasts (MEFs) obtained from MBT/Pas foetuses allows higher viral production than BALB/cByJ MEFs.
A new mouse model reveals a critical role for host innate immunity in resistance to Rift Valley fever.
Specimen part
View SamplesWallerian degeneration (WD) involves the fragmentation of axonal segments disconnected from their cell bodies, segmentation of the myelin sheath, and removal of debris by Schwann cells and immune cells. The removal and downregulation of myelin-associated inhibitors of axonal regeneration and synthesis of growth factors by these two cell types are critical responses to successful nerve repair. Here, we analyzed the transcriptome of the sciatic nerve of mice carrying the Wallerian degeneration slow (WldS) mutant gene, a gene that confers axonal protection in the distal stump after injury, therefore causing significant delays in WD, neuroinflammation, and axonal regeneration.
Transcriptional profiling of the injured sciatic nerve of mice carrying the Wld(S) mutant gene: identification of genes involved in neuroprotection, neuroinflammation, and nerve regeneration.
Specimen part, Time
View SamplesSle2c1 is an NZM2410-derived lupus susceptibility locus that induces an expansion of the B1a cell compartment. B1a cells have a repertoire enriched for autoreactivity, and an expansion of this B cell subset occurs in several mouse models of lupus. Here we showed that expression of Sle2c1 enhances NZB cellular phenotypes that have been associated with autoimmune pathogenesis. A combination of genetic mapping and candidate gene analysis presents Cdkn2c, a gene encoding for cyclin kinase inhibitor p18INK4c (p18), as the top candidate gene for inducing the Slec2c1 associated expansion of B1a cells. A novel SNP in the Cdkn2c promoter is associated with a significantly reduced Cdkn2c expression in the splenic B cells and B1a cells from Sle2c1-carrying mice, which leads to defective G1 cell cycle arrest in splenic B cells and increased proliferation of Pc B1a cells. As cell cycle is differentially regulated in B1a and B2 cells, these results suggest that Cdkn2c play a critical role in B1a cell self renewal, and that its impaired expression leads to an accumulation of these cells with high autoreactive potential.
Cyclin-dependent kinase inhibitor Cdkn2c regulates B cell homeostasis and function in the NZM2410-derived murine lupus susceptibility locus Sle2c1.
Specimen part
View SamplesTo elucidate the mechanism of BCL6-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed BCL6+/+ and BCL6-/- B cell precursors. Pharmacological inhibition of BCR-ABL1 was performed with the BCR-ABL1 kinase inhibitor STI571 (Imatinib).
BCL6 is critical for the development of a diverse primary B cell repertoire.
Sex, Age, Specimen part, Treatment
View SamplesWe characterized gene expression changes in the developing mouse liver at gestational days (GD) 11.5, 12.5, 13.5, 14.5, 16.5, and 19.5 and in the neonate (postnatal day (PND) 7 and 30) using full-genome microarrays and compared these changes to that in the adult liver. The fetal liver, and to a lesser extent the neonatal liver, exhibited dramatic differences in gene expression compared to adults. Canonical pathway analysis of the fetal liver signature demonstrated increases in functions important in cell replication and DNA fidelity whereas most metabolic pathways of intermediary metabolism were suppressed. Comparison of the dataset to a number of previously published datasets revealed 1) a striking similarity between the fetal liver and that of the pancreas in both mice and humans, 2) a nucleated erythrocyte signature in the fetus and 3) suppression of most xenobiotic metabolism genes throughout development, except a number of transporters associated with expression in hematopoietic cells.
Transcriptional ontogeny of the developing liver.
Specimen part
View SamplesPURPOSE: Hyperoxia is toxic to photoreceptors, and this toxicity may be important in the progress of retinal dystrophies. This microarray study examines gene expression induced in the C57BL/6J mouse retina by hyperoxia over the 14-day period during which photoreceptors first resist, then succumb to, hyperoxia. METHODS: Young adult C57BL/6J mice were exposed to hyperoxia (75% oxygen) for up to 14 days. On day 0 (control), day 3, day 7, and day 14, retinal RNA was extracted and processed on Affymetrix GeneChip Mouse Genome 430 2.0 arrays. Microarray data were analyzed using GCOS Version 1.4 and GeneSpring Version 7.3.1. RESULTS: The overall numbers of hyperoxia-regulated genes increased monotonically with exposure. Within that increase, however, a distinctive temporal pattern was apparent. At 3 days exposure, there was prominent upregulation of genes associated with neuroprotection. By day 14, these early-responsive genes were downregulated, and genes related to cell death were strongly expressed. At day 7, the regulation of these genes was mixed, indicating a possible transition period from stability at day 3 to degeneration at day 14. CONCLUSIONS: Microarray analysis of the response of the retina to prolonged hyperoxia demonstrated a temporal pattern involving early neuroprotection and later cell death, and provided insight into the mechanisms involved in the two phases of response. As hyperoxia is a consistent feature of the late stages of photoreceptor degenerations, understanding the mechanisms of oxygen toxicity may be important therapeutically.
Gene regulation induced in the C57BL/6J mouse retina by hyperoxia: a temporal microarray study.
Specimen part
View SamplesExosomes are small extracellular nano-vesicles of endocytic origin that mediate different signals between cells, by surface interactions and by shuttling of functional RNA from one cell to another. In this study, we show that exosomes, produced by mouse mast cells exposed to oxidative stress, change their mRNA content and also that these exosomes can influence the response of other cells to oxidative stress by providing recipient cells with a resistance against oxidative stress. Finally, we also show that UV-light affect the biological functions associated with exosomes released under oxidative stress. These results argue that exosomal shuttle of RNA is involved in cell-to-cell communication, by influencing the response of recipient cells to an external stimulus.
Exosomes communicate protective messages during oxidative stress; possible role of exosomal shuttle RNA.
Specimen part, Cell line
View SamplesTo characterize the effect of menthol on macrophages, comprehensive microarray analysis was performed in RAW 264.7 macrophage.
Menthol, a unique urinary volatile compound, is associated with chronic inflammation in interstitial cystitis.
Cell line, Treatment
View SamplesDuring mammalian kidney development, mesenchymal nephron progenitors (cap mesenchyme) differentiate into the epithelial cells that go on to form the nephron. Although differentiation of nephron progenitors is triggered by activation of Wnt/b-catenin signaling, constitutive activation of Wnt/b-catenin signaling blocks epithelialization of nephron progenitors. Full epithelialization of nephron progenitors requires transient activation of Wnt/b-catenin signaling. We performed transcriptional profiling of nephron progenitors responding to constitutive or transient activation of Wnt/b-catenin signaling.
Six2 and Wnt regulate self-renewal and commitment of nephron progenitors through shared gene regulatory networks.
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