Calorie restriction (CR) is a dietary regimen that supports healthy aging. In this study we investigated the systemic and liver-specific responses caused by a diet switch to a medium-fat (MF) diet in 24-month-old life-long, CR-exposed mice. This study aimed to increase the knowledge base on dietary alterations of gerontological relevance. Nine-week-old C57BL/6J mice were exposed either to a control, CR or MF diet. At the age of 24 months, a subset of mice of the CR group was transferred to ad libitum MF feeding (CR-MF).The mice were sacrificed at the age of 28 months, then biochemical and molecular analyses were performed. Our results showed that, despite the long-term exposure to the CR regimen, mice in the CR-MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR-improved survival was observed in the diet switch group. The liver transcriptomic profile of CR-MF mice largely shifted to a profile similar to the MF-fed animals but leaving ~22% of the 1578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the life-long CR group. Therefore, although the diet switch was performed at an old age, the CR-MF-exposed mice showed plasticity in coping with the challenge of a MF diet without developing severe liver pathologies.
Plasticity of lifelong calorie-restricted C57BL/6J mice in adapting to a medium-fat diet intervention at old age.
Sex
View SamplesSertoli cells (SCs), the only somatic cells within seminiferous tubules, associate intimately with developing germ cells. They not only provide physical and nutritional support but also secrete factors essential to the complex developmental processes of germ cell proliferation and differentiation. The SC transcriptome must therefore adapt rapidly during the different stages of spermatogenesis. We report comprehensive genome-wide expression profiles of pure populations of SCs isolated at 5 distinct stages of the first wave of mouse spermatogenesis, using RNA sequencing technology. We were able to reconstruct about 13 901 high-confidence, nonredundant coding and noncoding transcripts, characterized by complex alternative splicing patterns with more than 45% comprising novel isoforms of known genes. Interestingly, roughly one-fifth (2939) of these genes exhibited a dynamic expression profile reflecting the evolving role of SCs during the progression of spermatogenesis, with stage-specific expression of genes involved in biological processes such as cell cycle regulation, metabolism and energy production, retinoic acid synthesis, and blood-testis barrier biogenesis. Finally, regulatory network analysis identified the transcription factors endothelial PAS domain-containing protein 1 (EPAS1/Hif2a), aryl hydrocarbon receptor nuclear translocator (ARNT/Hif1ß), and signal transducer and activator of transcription 1 (STAT1) as potential master regulators driving the SC transcriptional program. Our results highlight the plastic transcriptional landscape of SCs during the progression of spermatogenesis and provide valuable resources to better understand SC function and spermatogenesis and its related disorders, such as male infertility. Overall design: Genome-wide expression profiling analysis using Illumina next-generation sequencing technology
Research resource: the dynamic transcriptional profile of sertoli cells during the progression of spermatogenesis.
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Nuclear ARRB1 induces pseudohypoxia and cellular metabolism reprogramming in prostate cancer.
Specimen part, Cell line
View SamplesBeta-arrestin 1 (ARRB1) has been implicated in transcriptional regulation as part of protein complexes bound to chromatin. Here we investigate its effect on transcription and its potential impact on prostate cancer. We report the first genome-wide mapping of chromatin binding for ARRB1 and combine it with expression array data to define its transcriptome. We identify Hypoxia Inducible Factor 1A (HIF1A) as a nuclear binding partner that recruits ARRB1 to promoter regions of HIF1A targets. We show that ARRB1 modulates HIF1A-dependent transcription and promotes a shift in cellular metabolism from oxidative phosphorylation to aerobic glycolysis. In addition, we show that ARRB1 plays an important role in neoplastic transformation, cell growth and resistance to hypoxic stress. This is the first example of an endocytic adaptor protein regulating metabolic pathways and implicates ARRB1 as a tumour promoter.
Nuclear ARRB1 induces pseudohypoxia and cellular metabolism reprogramming in prostate cancer.
Specimen part, Cell line
View SamplesT4 and T5 neurons are components of the neuronal circuit for motion vision in flies. To identify genes involved in neuronal computation of T4 and T5 neurons, we perfomed transcriptome analysis. Nuclei of T4 and T5 neurons were immunoprecipitated, total RNA was harvested and used for mRNA-seq with Illumina technology. In two biological replicates, we mapped 154 and 119 million reads to D. melanogaster genome. mRNA-seq provided information about expression levels of 17,468 annotated transcripts in the T4 and T5 neurons. Overall design: Cell type – specific transcriptome analysis of the RNA isolated from immunoprecipitated nuclei, performed in two biological replicates
RNA-Seq Transcriptome Analysis of Direction-Selective T4/T5 Neurons in Drosophila.
Subject
View SamplesX-chromosome inactivation (XCI) provides a dosage compensation mechanism where, in each female cell, one of the two X chromosomes is randomly silenced. However, some genes on the inactive X chromosome and outside the pseudoautosomal regions escape from XCI and are expressed from both alleles (escapees). We investigated XCI at single-cell resolution combining deep single cellRNA sequencing with whole-genome sequencing to examine allelic-specific expression in 935 primary fibroblast and 48 lymphoblastoid single cells from five female individuals. In this framework we integrated an original method to identify and exclude doublets of cells. In fibroblast cells, we have identified 55 genes as escapees including five novel escapee genes. Moreover, we observed that all genes exhibit a variable propensity to escape XCI in each cell and cell type and that each cell displays a distinct expression profile of the escapee genes. A metric, the Inactivation Score—defined as the mean of the allelic expression profiles of the escapees per cell—enables us to discover a heterogeneous and continuous degree of cellular XCI with extremes represented by “inactive” cells, i.e., cells exclusively expressing the escaping genes from the active X chromosome and “escaping” cells expressing the escapees from both alleles. We found that this effect is associated with cell-cycle phases and, independently, with the XIST expression level, which is higher in the quiescent phase (G0). Single-cell allele-specific expression is a powerful tool to identify novel escapees in different tissues and provide evidence of an unexpected cellular heterogeneity of XCI. Overall design: Single-cell RNA seq study on 935 human fibroblasts and 48 lymphoblastoid cells from 5 female individuals, in order to investigate the X chromosome nactivation mechanism on a single cell level and to identify escapee genes
Single cell transcriptome in aneuploidies reveals mechanisms of gene dosage imbalance.
Specimen part, Subject
View SamplesDown syndrome (DS) results from trisomy of chromosome 21 (HSA21). Some DS phenotypes may be directly or indirectly related to the increased expression of specific HSA21 genes, in particular those encoding transcription factors. The HSA21 encoded Single-minded 2 (SIM2) transcription factor has key neurological functions and is a good candidate to be involved in the cognitive impairment of DS. ChIP-sequencing was used to map SIM2 binding in mouse embryonic stem cells and has revealed 1229 high-confidence SIM2-binding sites. Analysis of the SIM2 target genes confirmed the importance of SIM2 in developmental and neuronal processes and indicated that SIM2 may be a master transcription regulator. Indeed, SIM2 DNA binding sites share sequence specificity and overlapping domains of occupancy with master transcription factors such as SOX2, OCT4, NANOG or KLF4. The association between SIM2 and these pioneer factors is supported by the finding that SIM2 can be co-immunoprecipitated with SOX2, OCT4, NANOG or KLF4. Furthermore, the binding of SIM2 marks a particular sub-category of enhancers known as super-enhancers. These regions are characterized by typical DNA modifications and Mediator co-occupancy (MED1 and MED12). Altogether, we provide evidence that SIM2 binds a specific set of enhancer elements thus explaining how SIM2 can regulate its gene network in DS neuronal features. Overall design: RNA-Seq analysis in Sim2 expressing cells (3 replicates A6, B8, C4) and EB3 control cells (3 replicates)
HSA21 Single-Minded 2 (Sim2) Binding Sites Co-Localize with Super-Enhancers and Pioneer Transcription Factors in Pluripotent Mouse ES Cells.
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View SamplesThe activation of endothelium by tumor cells is one of the main steps by tumor metastasis. The role of the blood components (platelets and leukocytes) in this process remain unclear.
Selectin-mediated activation of endothelial cells induces expression of CCL5 and promotes metastasis through recruitment of monocytes.
Specimen part
View SamplesThe HSA21-mES Cell Bank includes, in triplicate clones, thirty-two murine orthologs of HSA21 genes, which can be overexpressed in an inducible manner using the Tet-off system integrated in the Rosa26 locus.
A mouse embryonic stem cell bank for inducible overexpression of human chromosome 21 genes.
Specimen part
View SamplesElevated levels of androgen receptor (AR) in prostate cancer confer resistance to current antiandrogens and play a causal role in disease progression due to persistent target gene activation. Through pharmacologic and genetic approaches, we show that half of all direct AR target genes, including TMPRSS2, the primary driver of ETS fusion transcripts in 70 percent of human prostate cancers, require histone deacetylase (HDAC) activity for transcriptional activation by AR. Surprisingly, the HDAC3-NCoR complex, which typically functions to repress gene expression by nuclear receptors, is required for AR target gene activation. Prostate cancer cells treated with HDAC inhibitors have reduced AR protein levels, but we show that the mechanism of blockade of AR activity is through failure to assemble a coactivator/RNA polymerase II complex after AR binds to the enhancers of target genes. Failed complex assembly is associated with a phase shift in the cyclical wave of AR recruitment that typically occurs in response to ligand treatment. HDAC inhibitors retain the ability to block AR activity in hormone refractory prostate cancer models and therefore merit clinical investigation in this setting. HDAC-regulated AR target genes defined here can serve as biomarkers to ensure sufficient levels of HDAC inhibition.
Histone deacetylases are required for androgen receptor function in hormone-sensitive and castrate-resistant prostate cancer.
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