The counterregulatory response to hypoglycemia, which restores normal blood glucose levels to ensure sufficient provision of glucose to the brain, is critical for survival. To discover underlying brain regulatory systems, we performed a genetic screen in recombinant inbred mice for quantitative trait loci (QTL) controlling glucagon secretion in response to neuroglucopenia. We identified a QTL on the distal part of chromosome 7 and combined this genetic information with transcriptomic analysis of hypothalami. This revealed Fgf15 as the strongest candidate to control the glucagon response. Fgf15 was found to be expressed by neurons of the dorsomedial hypothalamus and the perifornical area. Intracerebroventricular injection of FGF19, the human ortholog of Fgf15, reduced activation by neuroglucopenia of dorsal vagal complex neurons and of the parasympathetic nerve, leading to a lower glucagon secretion. These data show that Fgf15 in hypothalamic neurons is a regulator of vagal nerve activity in response to neuroglucopenia. Overall design: 36 BXD strains + 4 parental strains, 1 time point, basal condition without treatment
A Genetic Screen Identifies Hypothalamic Fgf15 as a Regulator of Glucagon Secretion.
Specimen part, Cell line, Subject
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 SamplesCells that have been pre-exposed to mild stress (priming stress) acquire transient resistance to subsequent severe stress even under different combinations of stresses. This phenomenon is called cross-tolerance. Although it has been reported that cross-tolerance occurs in many organisms, the molecular basis is not clear yet. Here, we identified slm9+ as a responsible gene for the cross-tolerance in the fission yeast Schizosaccharomyces pombe. Slm9 is a homolog of mammalian HIRA histone chaperone. HIRA forms a conserved complex and gene disruption of other HIRA complex components, Hip1, Hip3, and Hip4, also yielded a cross-tolerance-defective phenotype, indicating that the fission yeast HIRA is involved in the cross-tolerance as a complex. We also revealed that Slm9 was recruited to the stress-responsive gene loci upon stress treatment in an Atf1-dependent manner. The expression of stress-responsive genes under stress conditions was compromised in HIRA disruptants. Consistent with this, Pol II recruitment and nucleosome eviction at these gene loci were impaired in slm9D cells. Furthermore, we found that the priming stress enhanced the expression of stress-responsive genes in wild-type cells that were exposed to the severe stress. These observations suggest that HIRA functions in stress response through transcriptional regulation.
HIRA, a conserved histone chaperone, plays an essential role in low-dose stress response via transcriptional stimulation in fission yeast.
No sample metadata fields
View SamplesBlood was extracted from embryonic hearts at E4 and E6 and non-red blood was separated by density gradient centrifugation
Expression profiling of circulating non-red blood cells in embryonic blood.
No sample metadata fields
View SamplesHumoral responses of mice specifically deleted for Moz (a histone acetyltransferase) or c-Myb (a transcription factor) in B cells were aberrant. RNA-sequencing analysis was performed to assess gene expression differences compared to wild-type controls in germinal center B cells or plasmablasts. Overall design: Moz f/f Aicda1-Cre, Aicda1-Cre, Myb f/f Cd23-Cre, Mybf/f (no cre) mice were immunized with NP-KLH precipitated in alum and germinal center B cells were sort-purified. Secondary plasmablasts were sort-purified from immunized mice boosted with NP-KLH in PBS (Myb experiment). Two independent experiments were conducted.
Regulation of germinal center responses and B-cell memory by the chromatin modifier MOZ.
Specimen part, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Identification of key regions and genes important in the pathogenesis of sezary syndrome by combining genomic and expression microarrays.
Specimen part, Disease
View SamplesThis study used tumour and paired normal samples from 28 Szary Syndrome (SS) patients to define recurrent regions of chromosomal aberrations. Our data identified recurrent losses of 17p13.2-p11.2 and 10p12.1-q26.3 occurring in 71 and 68% of cases respectively; common gains were detected for 17p11.2-q25.3 (64%) and chromosome 8/8q (50%). Moreover, we identified novel genomic lesions recurring in more than 30% of tumours: loss of 9q13-q21.33 and gain of 10p15.3-10p12.2. In the Szary Syndrome cases analysed, we could find several small and few large Uniparental Disomies involving interstitial or telomeric regions of LOH occurring mainly for chromosome 10 and to a lesser extent for chromosome 9 and 17. In the attempt to correlate Copy Number data and clinical parameters we find a relationship between complex pattern of chromosomal aberrations, involving at least three recurrent Copy Number alterations, and shorter survival. Integrating mapping and transcriptional data we were able to identify a total of 113 deregulated transcripts in aberrant chromosomal regions that included cancer related genes such as members of the NF-kB pathway (BAG4, BTRC, NKIRAS2, PSMD3, TRAF2) that might explain its constitutive activation in CTCL. Matching this list of genes with those discriminating patients with different survival times we identify several common candidates that might exert critical roles in Szary Syndrome, like BUB3 and PIP5K1B.
Identification of key regions and genes important in the pathogenesis of sezary syndrome by combining genomic and expression microarrays.
Specimen part, Disease
View SamplesTo identify molecular pathophysiologic changes and novel disease mechanisms specific to myelomeningocele by analyzing AFS cfRNA in fetuses with open myelomeningocele.
Amniotic fluid transcriptomics reflects novel disease mechanisms in fetuses with myelomeningocele.
No sample metadata fields
View SamplesScreening for genes regulated by Etv2 within Flk-1+/PDGFRa+ ES derived mesoderm.Microarray analysis performed to screen for the candidate genes regulated by Etv2. TT2 ES cells differentiated on OP9 feeder cells were sorted using Flk-1 and PDGFRa antibodies.Gene expressions from these two populations were compared.
Etv2/ER71 induces vascular mesoderm from Flk1+PDGFRα+ primitive mesoderm.
Cell line
View SamplesScreening for genes up in Etv2+ cells within Flk-1+ ES derived mesoderm
Etv2/ER71 induces vascular mesoderm from Flk1+PDGFRα+ primitive mesoderm.
Cell line
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