Evolutionary conserved biological rhythms play a fundamental role in the physiology and behavior of all light-sensitive organisms. Generation of rhythmic expression of clock-controlled genes is orchestrated by a molecular circadian clock constitutes by interconnected negative feedback loops of transcription factors. In this study, we want to characterize gene which also present a rhythmic translation through the characterization of genes with a rhythmic polysomal/total RNA ratio.
The circadian clock coordinates ribosome biogenesis.
Sex, Age, Specimen part, Disease, Time
View SamplesA preliminary understanding of the phenotypic effect of copy number variation (CNV) of DNA segments is emerging. These rearrangements were demonstrated to influence, in a somewhat dose-dependent manner, the expression of genes mapping within. They were shown to also affect the expression of genes located on their flanks, sometimes at great distance. Here, we show by monitoring these effects at multiple life stages, that these controls over expression are effective throughout mouse development. Similarly, we observe that the more specific spatial expression patterns of CNV genes are maintained throughout life. However, we find that some brain-expressed genes appear to be under compensatory loops only at specific time-points, indicating that the influence of CNVs on these genes is modulated through development. We also observe that CNV genes are significantly enriched upon transcripts that show variable time-course of expression in different strains. Thus modifying the number of copy of a gene not only potentially alters its expression level, but possibly also its time of expression.
Copy number variation modifies expression time courses.
Sex, Age, Specimen part
View SamplesTo study the effect of structural changes on expression, we assessed gene expression in genomic disorder mouse models. Both a microdeletion and its reciprocal microduplication mapping to mouse chromosome 11 (MMU11), which model the rearrangements present in Smith-Magenis (SMS) and Potocki-Lupski (PTLS) syndromes patients, respectively, have been engineered. We profiled the transcriptome of five different tissues affected in human patients in mice with 1n (Deletion/+), 2n (+/+), 3n (Duplication/+) and uniallelic 2n (Deletion/Duplication) copies of the same region in an identical genetic background. The most differentially expressed transcripts between the four studied genotypes were ranked. A highly significant propensity, are mapping to the engineered SMS/PTLS interval in the different tissues. A statistically significant overrepresentation of the genes mapping to the flanks of the engineered interval was also found in the top-ranked differentially expressed genes. A phenomenon efficient across multiple cell lineages and that extends along the entire length of the chromosome, tens of megabases from the breakpoints. These long-range effects are unidirectional and uncoupled from the number of copies of the copy number variation (CNV) genes. Thus, our results suggest that the assortment of genes mapping to a chromosome is not random. They also indicate that a structural change at a given position of the human genome may cause the same perturbation in particular pathways regardless of gene dosage. An issue that should be considered in appreciating the contribution of this class of variation to phenotypic features.
No associated publication
Sex
View SamplesRenal excretion of water and major electrolytes exhibits a significant circadian rhythm. This functional periodicity is believed to result, at least in part, from circadian changes in secretion/reabsorption capacities of the distal nephron and collecting ducts. Here, we studied the molecular mechanisms underlying circadian rhythms in the distal nephron segments, i.e. distal convoluted tubule (DCT) and connecting tubule (CNT) and, the cortical collecting duct (CCD). Temporal expression analysis performed on microdissected mouse DCT/CNT or CCD revealed a marked circadian rhythmicity in the expression of a large number of genes crucially involved in various homeostatic functions of the kidney. This analysis also revealed that both DCT/CNT and CCD possess an intrinsic circadian timing system characterized by robust oscillations in the expression of circadian core clock genes (clock, bma11, npas2, per, cry, nr1d1) and clock-controlled Par bZip transcriptional factors dbp, hlf and tef. The clock knockout mice or mice devoid of dbp/hlf/tef (triple knockout) exhibit significant changes in renal expression of several key regulators of water or sodium balance (vasopressin V2 receptor, aquaporin-2, aquaporin-4, alphaENaC). Functionally, the loss of clock leads to a complex phenotype characterized by partial diabetes insipidus, dysregulation of sodium excretion rhythms and a significant decrease in blood pressure. Collectively, this study uncovers a major role of molecular clock in renal function.
Molecular clock is involved in predictive circadian adjustment of renal function.
Sex, Specimen part
View SamplesMost metabolic studies are conducted in male animals; thus, the molecular mechanism controlling gender-specific pathways has been neglected, including sex-dependent responses to peroxisome proliferator-activated receptors (PPARs). Here we show that PPARalpha has broad female-dependent repressive actions on hepatic genes involved in steroid metabolism and inflammation. In males, this effect is reproduced by the administration of synthetic PPARalpha ligand. Using the steroid hydroxylase gene Cyp7b1 as a model, we elucidated the molecular mechanism of this PPARalpha-dependent repression. Initial sumoylation of the ligand-binding domain of PPARalpha triggers the interaction of PPARalpha with the GA-binding protein alpha bound to the target promoter. Histone deacetylase is then recruited, and histones and adjacent Sp1-binding site are methylated. These events result in the loss of Sp1-stimulated expression, and thus the down-regulation of Cyp7b1. Physiologically, this repression confers protection against estrogen-induced intrahepatic cholestasis, paving the way for a novel therapy against the most common hepatic disease during pregnancy.
Sumoylated PPARalpha mediates sex-specific gene repression and protects the liver from estrogen-induced toxicity in mice.
No sample metadata fields
View SamplesNarcolepsy is a sleep disorder characterized by excessive daytime sleepiness and attacks of muscle atonia triggered by strong emotions (cataplexy). The best biological marker of narcolepsy is orexin deficiency with dramatic loss in hypothalamic orexin-producing neurons. Together with a tight HLA and T-cell receptor alpha(5) association, narcolepsy is believed to be autoimmune although all attempts to prove it have failed.To characterize orexin specific peptides we produced a transgenic mouse model to access to the orexin neurons transcription profile. We generated BAC-based transgenic mice by replacing the orexin coding sequence by a flag-tagged poly(A) binding protein (Pabp1) cDNA sequence. The basis of this construct is to take advantage of the ability of Pabp1 to bind to the poly(A) tails of mRNAs in vivo. Thus mRNAs from orexin cells are expected to be enriched by cross-linking them to the flag-tagged PABP and then co-immunoprecipitating this complex with a specific anti-flag monoclonal antibody.
Elevated Tribbles homolog 2-specific antibody levels in narcolepsy patients.
Age
View SamplesRegulation of mRNA stability by RNA-protein interactions contributes significantly to quantitative aspects of gene expression. We have identified potential mRNA targets of the AU-rich element binding protein AUF1. Myc-tagged AUF1 p42 was induced in mouse NIH-3T3 cells and RNA-protein complexes isolated using anti-myc tag antibody beads. Bound mRNAs were analyzed with Affymetrix microarrays. We have identified 508 potential target mRNAs that were at least 3-fold enriched compared to control cells without myc-AUF1. 22.3% of the enriched mRNAs had an AU-rich cluster in the ARED Organism database, against 16.3% of non-enriched control mRNAs. The enrichment towards AU-rich elements was also visible by AREScore with an average value of 5.2 in the enriched mRNAs versus 4.2 in the control group. Yet, many mRNAs were enriched without a high ARE score suggesting that AUF1 has a broader binding spectrum than standard AUUUA repeats. AUF1 did not preferentially bind to unstable mRNAs. Still, some enriched mRNAs were highly unstable, as those of TNFSF11 (known as RANKL), KLF10, HES1, CCNT2, SMAD6, and BCL6. We have mapped some of the instability determinants. HES1 mRNA appeared to have a coding region determinant. Detailed analysis of the RANKL and BCL6 3UTR revealed for both that full instability required two elements, which are conserved in evolution. In RANKL mRNA both elements are AU-rich and separated by 30 bases, while in BCL6 mRNA one is AU-rich and 60 bases from a non AU-rich element that potentially forms a stem-loop structure.
Short-lived AUF1 p42-binding mRNAs of RANKL and BCL6 have two distinct instability elements each.
Cell line
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Homer1a is a core brain molecular correlate of sleep loss.
No sample metadata fields
View SamplesCopy number variation (CNV) of DNA segments has recently been identified as a major source of genetic diversity, but a more comprehensive understanding of the extent and phenotypic effect of this type of variation is only beginning to emerge. In this study we generated genome-wide expression data from 6 mouse tissues to investigate how CNVs influence gene expression.
Segmental copy number variation shapes tissue transcriptomes.
No sample metadata fields
View SamplesThese studies adress differential changes in gene expression between sleep deprived and control mice. We profiled gene expression at four time points across the 24H Light/Dark cycle to take into account circadian influences and used three different inbred strains to understand the influence of genetic background.
Homer1a is a core brain molecular correlate of sleep loss.
No sample metadata fields
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