Project description:Telomeres constitute the ends of linear chromosomes and together with the shelterin complex form a structure essential for genome maintenance and stability. In addition to the constitutive binding of the shelterin complex, other direct, yet more transient interactions are mediated by the CST complex and HOT1, while subtelomeric variant repeats are recognized by NR2C/F transcription factors. Recently, the Kruppel-like zinc finger protein ZBTB48 has been described as a novel telomere-associated factor in the vertebrate lineage. Here, we show that ZBTB48 binds directly both to telomeric as well as to subtelomeric variant repeat sequences. ZBTB48 is found at telomeres of human cancer cells regardless of the mode of telomere maintenance and it acts as a negative regulator of telomere length. In addition to its telomeric function, we demonstrate through a combination of RNAseq, ChIPseq and expression proteomics experiments that ZBTB48 acts as a transcriptional activator on a small set of target genes, including mitochondrial fission process 1 (MTFP1). This discovery places ZBTB48 at the interface of telomere length regulation, transcriptional control and mitochondrial metabolism.
Project description:<p>Gene expression is a biological process regulated at different molecular levels, including chromatin accessibility, transcription, and RNA maturation and transport. In addition, these regulatory mechanisms have strong links with cellular metabolism. Here we present a multi-omics dataset that captures different aspects of this multi-layered process in yeast. We obtained RNA-seq, metabolomics, and H4K12Ac ChIP-seq data for wild-type and mip6delta strains during a heat-shock time course. Mip6 is an RNA-binding protein that contributes to RNA export during environmental stress and is informative of the contribution of post-transcriptional regulation to control cellular adaptations to environmental changes. The experiment was performed in quadruplicate, and the different omics measurements were obtained from the same biological samples, which facilitates the integration and analysis of data using covariance-based methods. We validate our dataset by showing that ChIP-seq, RNA-seq and metabolomics signals recapitulate existing knowledge about the response of ribosomal genes and the contribution of trehalose metabolism to heat stress.</p>
Project description:Accumulating evidence suggests important roles of RNAs interacting with genomic regions in the regulation of genome functions including X chromosome inactivation and gene expression. However, no method to identify RNAs interacting with a given genomic region in a non-biased manner has been reported. Here, we used engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) combined with the RNA-Seq analysis (enChIP-RNA-Seq) to perform non-biased search of RNAs interacting with telomeres. In enChIP-RNA-Seq, the target genomic regions are captured with an engineered DNA-binding molecule such as a TAL protein. Subsequently, RNAs are purified and subjected to the RNA-Seq analysis. The detected RNAs contained known telomere-binding RNAs including telomerase RNA and Cajal body-specific RNAs. In addition, we detected many novel telomere-binding RNAs. We confirmed binding of candidate RNAs to telomeres by the enChIP-RT-PCR analysis. Identified novel telomere-binding RNAs may play important roles in telomere functions. In addition, our results suggest that enChIP-RNA-Seq analysis would be useful for identification of RNAs interacting with specific genomic regions. RNAs associated with telomeres were identified by using the enChIP technology combined with deep sequencing using Illumina Miseq. Briefly, to isolate telomeres, a TAL protein, Telomere-TAL (Tel-TAL), recognizing a 19-bp sequence containing an array of TTAGGG (telomere repeats) was fused with 3xFLAG tag and NLS (3xFN-Tel-TAL) and LexA protein (3xFNLDD)11 were expressed in a mouse hematopoietic cell line, Ba/F3, respectively. The cells were crosslinked with formaldehyde, and crosslinked chromatin was fragmented by sonication. Subsequently, chromatin complexes containing 3xFN-Tel-TAL or 3xFNLDD were immunoprepicitated with anti-FLAG M2 Ab. Supplementary URL: http://www.nature.com/srep/2013/131108/srep03171/full/srep03171.html
Project description:Repressor-activator protein 1 (scRap1) is the major binding activity at Saccharomyces cerevisiae telomeres, with roles in telomere length regulation and establishment of subtelomeric silencing by recruiting the Sir proteins. scRap1 also acts as a transcription factor controlling the expression of ribosomal proteins and glycolytic enzymes. A homolog of scRap1 exist in mammals, Rap1 (also known as Terf2ip), however, its roles in telomere biology and transcriptional regulation are largely unknown. We have employed microarrays to obtain gene expression signatures related to Rap1-deleted mice when compared to the wild-type.
Project description:Accumulating evidence suggests important roles of RNAs interacting with genomic regions in the regulation of genome functions including X chromosome inactivation and gene expression. However, no method to identify RNAs interacting with a given genomic region in a non-biased manner has been reported. Here, we used engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) combined with the RNA-Seq analysis (enChIP-RNA-Seq) to perform non-biased search of RNAs interacting with telomeres. In enChIP-RNA-Seq, the target genomic regions are captured with an engineered DNA-binding molecule such as a TAL protein. Subsequently, RNAs are purified and subjected to the RNA-Seq analysis. The detected RNAs contained known telomere-binding RNAs including telomerase RNA and Cajal body-specific RNAs. In addition, we detected many novel telomere-binding RNAs. We confirmed binding of candidate RNAs to telomeres by the enChIP-RT-PCR analysis. Identified novel telomere-binding RNAs may play important roles in telomere functions. In addition, our results suggest that enChIP-RNA-Seq analysis would be useful for identification of RNAs interacting with specific genomic regions.
Project description:The TTAGGG motif is common to two seemingly unrelated dimensions of chromatin function M-^V the vertebrate telomere repeat and the promoter regions of many Schizosaccharomyces pombe genes, including all of those encoding canonical histones. The essential S. pombe protein Teb1 contains two Myb-like DNA binding domains related to those found in telomere proteins and binds the human telomere repeat sequence TTAGGG. Here we analyze Teb1 binding throughout the genome and the consequences of reduced Teb1 function. ChIP on chip analysis reveals robust Teb1 binding at many promoters, notably including all of those controlling canonical histone gene expression. A hypomorphic allele, teb1-1, confers reduced binding and reduced levels of histone transcripts. teb1-1 cells also show severe defects in the G1-arrest-associated clipping of histones, most likely due to a role for Teb1 in promoting expression of the protease Isp6. Prompted by previously suggested connections between histone expression and centromere identity, we examined localization of the centromeric histone H3 variant Cnp1 and found reduced centromeric binding along with reduced centromeric silencing. These data identify Teb1 as a master regulator of histone levels and centromere identity.
Project description:Cellular senescence due to telomere dysfunction has been hypothesized to play a role in age-associated diseases including idiopathic pulmonary fibrosis (IPF). It has been postulated that paracrine mediators originating from senescent alveolar epithelia signal to surrounding mesenchymal cells and contribute to disease pathogenesis. However, murine models of telomere-induced alveolar epithelial senescence fail to display the canonical senescence-associated secretory phenotype (SASP) that is observed in senescent human cells. In an effort to understand human-specific responses to telomere dysfunction, we modelled telomere dysfunction-induced senescence in a human alveolar epithelial cell line. We hypothesized that this system would enable us to probe for differences in transcriptional and proteomic senescence pathways in vitro and to identify novel secreted protein (secretome) changes that potentially contribute to the pathogenesis of IPF. Following induction of telomere dysfunction, a robust senescence phenotype was observed. RNA-Seq analysis of the senescent cells revealed the SASP and comparisons to previous murine data highlighted species-specific responses to telomere dysfunction. We then conducted a proteomic analysis of the senescent cells using a novel biotin ligase capable of labeling secreted proteins. Candidate biomarkers selected from our transcriptional and secretome data were then evaluated in IPF and control patient plasma. Four novel proteins were found to be differentially expressed between the patient groups: stanniocalcin-1, contactin-1, tenascin C, and total inhibin. Our data show that human telomere-induced, alveolar epithelial senescence results in a transcriptional SASP that is distinct from that seen in analogous murine cells. Our findings suggest that studies in animal models should be carefully validated given the species-specific responses to telomere dysfunction. We also describe a pragmatic approach for the study of the consequences of telomere-induced alveolar epithelial cell senescence in humans.
Project description:Here we show that ZBTB48 binds directly both to telomeric as well as to subtelomeric variant repeat sequences. ZBTB48 is found at telomeres of human cancer cells regardless of the mode of telomere maintenance and it acts as a negative regulator of telomere length. In addition to its telomeric function, we demonstrate through a combination of RNAseq, ChIPseq and expression proteomics experiments that ZBTB48 acts as a transcriptional activator on a small set of target genes, including mitochondrial fission process 1 (MTFP1). This discovery places ZBTB48 at the interface of telomere length regulation, transcriptional control and mitochondrial metabolism.