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Human telomerase requires TCAB1 for catalytic function and for shaping RNA component conformation

ABSTRACT: Ribonucleoprotein enzymes require specific and dynamic conformations of their RNA constituents for regulated catalysis. Telomerase RNA components (TRs) rely on two conserved domains, a pseudoknot/template sequence and a three-way junction (CR4/5), each of which binds the telomerase reverse transcriptase protein (TERT). Vertebrate TRs evolved a third element, the H/ACA domain, involved in assembly and trafficking of telomerase through binding telomerase cofactors, dyskerin and TCAB1, respectively. Here, we show that telomerase unexpectedly requires TCAB1 for enzyme catalysis and for shaping the conformation of the TR CR4/5 domain. Human and mouse cells lacking TCAB1 exhibit a marked reduction in telomerase activity, but show no defect in enzyme assembly. Instead, loss of TCAB1 causes specific unfolding of critical RNA helices in TR CR4/5 required for catalysis, and impairs TR-TERT association. CR4/5 mutations derived from patients with the telomere disorder dyskeratosis congenita phenocopy the loss of enzyme activity and disruption of TERT binding observed with TCAB1 deletion. These findings show that the H/ACA element acquired by telomerase during vertebrate evolution serves an unanticipated role in controlling folding of the essential TR CR4/5 domain, facilitating optimal TERT engagement and enabling telomerase catalysis through the action of TCAB1 protein tethered at the H/ACA domain.

ORGANISM(S): Homo sapiens

PROVIDER: GSE97486 | GEO | 2018/06/24

REPOSITORIES: GEO

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Proteomic analysis defines the interactome of telomerase in the protozoan parasite, Trypanosoma brucei

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2023-03-08 | PXD038235 | Pride

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2018-02-09 | GSE104672 | GEO

Comparing effects of mTR and mTERT deletion on gene expression and DNA damage response: MEF

Project description:Telomerase, the essential enzyme that maintains telomere length, contains two core components, TERT and TR. While early studies in yeast and mouse both indicated that loss of telomerase leads to phenotypes that arise after an increased number of generations, due to telomere shortening, recent studies claim additional roles for telomerase components in transcription and the response to DNA damage. To test these telomere length maintenance-independent roles of telomerase components, we examined first generation mTR-/- and mTERT-/- mice with long telomeres. We used gene expression profiling and found no genes that were expressed at significantly different levels when independent mTR-/- G1 mice were compared to mTERT-/- G1 mice and to wild-type mice. In addition, we compared the response to DNA damage in mTR-/-G1 and mTERT-/- G1 mouse embryonic fibroblasts, and found no increase in the response to DNA damage in the absence of either telomerase components compared to wild-type. We conclude that in the wild-type physiological telomere length setting, neither mTR nor mTERT act as a transcription factor or have a role in the DNA damage response.

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Comparing effects of mTR and mTERT deletion on gene expression and DNA damage response: liver

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Mutant thyroid hormone receptors (TRs) isolated from distinct cancer types display distinct target gene specificities: a unique regulatory repertoire associated with renal clear cell carcinomas.

Project description:Thyroid hormone receptors (TRs) are hormone-regulated transcription factors that regulate a diverse array of biological activities, including metabolism, homeostasis, and development. TRs also serve as tumor suppressors, and aberrant TR function (via mutation, deletion, or altered expression) is associated with a spectrum of both neoplastic and endocrine diseases. A particularly high frequency of TR mutations has been reported in renal clear cell carcinoma (RCCC) and in hepatocellular carcinoma (HCC). We have shown that HCC-TR mutants regulate only a fraction of the genes targeted by wild-type TRs, but have gained the ability to regulate other, unique, targets. We have suggested that this altered gene recognition may contribute to the neoplastic phenotype. Here, to determine the generality of this phenomenon, we examined a distinct set of TR mutants associated with RCCCs. We report that two different TR mutants, isolated from independent RCCC tumors, possess greatly expanded target gene specificities that extensively overlap one another, but only minimally overlap that of the WT-TRs, or those of two HCC-TR mutants. Many of the genes targeted by either or both RCCC-TR mutants have been previously implicated in RCCC, and include a series of metallothioneins, solute carriers, and genes involved in glycolysis and energy metabolism. We propose that TR mutations from RCCC and HCC are likely to play tissue-specific roles in carcinogenesis, and that the divergent target gene recognition patterns of TR mutants isolated from the two different types of tumors arises from different selective pressures during development of RCCC versus HCC. Gene expression was analyzed in HepG2 transformants expressing ectopic wildtype THRA, wildtype THRB, HCC-TR mutants ?? and ?N, and RCCC-TR mutants 6? and 15? using Affymetrix Human Gene 1.0 ST arrays in the presence or absence of T3. Each HepG2 transformant was assayed in triplicate.

2011-05-10 | E-GEOD-29159 | biostudies-arrayexpress

Mutant thyroid hormone receptors (TRs) isolated from distinct cancer types display distinct target gene specificities: a unique regulatory repertoire associated with renal clear cell carcinomas.

2011-05-10 | GSE29159 | GEO

Epigenomic landscapes of human inflammation associated macrophages [RNA-seq]

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2016-02-28 | E-GEOD-66593 | biostudies-arrayexpress

Epigenomic landscapes of human inflammation associated macrophages [ChIP-seq]

Project description:We previously demonstrated by genomic and bioinformatical approaches that human macrophage (MÎ¦) activation is best described by a spectrum model (Xue et al, Immunity, 2014). MÎ¦ integrate exogenous input signals on transcriptional level in a unique fashion to generate specific functional programs, enabling the plasticity in disease-related pathophysiologies. Such versatile responsiveness requires fast changes of transcription mediated by transcriptional regulators (TRs) or epigenomic changes. To better understand the principles of this regulation during human MÎ¦ activation, we assessed histone modifications including H3K4me1, H3K4me3, H3K27me3, and H3K27Ac by ChIP-sequencing allowing us to characterize the functional state of promoters (active, poised, repressed) and enhancers (active, inactive, intermediate). Using transcriptome data from our MÎ¦ spectrum model, we generated a co-regulation network of all TRs. Next, we overlaid epigenomic information and transcriptional changes of major TRs over time onto the TR network. We observed that input signals like IFNÎ³ or TNFÎ± induce a specific network of TRs that are transcriptionally regulated themselves, the combination of regulated TRs changes over time with a boost of transcriptional regulation of dozens of TRs 4 to 12 hrs post input signal exposure, almost all TRs within the network show active promoters, even if the TR itself is not expressed, and similar results are obtained for enhancers with open or at least intermediated states. These findings strongly suggest that in MÎ¦, the TR-defined cellular â??switch panelâ?? is always accessible thereby allowing MÎ¦ to quickly respond to the diverse input signal repertoire from the environment. Epigenetic analysis of promoter and enhancer sites in primary human macrophage subtypes and correlation to RNA-seq expression data

2016-02-28 | E-GEOD-66594 | biostudies-arrayexpress

GABP determines the epigenetic status of mutant TERT promoter

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PITX1 suppresses TERT transcription

Project description:Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line, B16F10, we have previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression. To identify the gene responsible for the regulation of TERT transcription, we performed cDNA microarray analysis using parental B16F10 cells, telomerase negative B16F10 microcell hybrids with a human chromosome 5 (B16F10MH5), and its revertant clones (MH5R) with reactivated telomerase. Here we report the identification of PITX1, whose restoration leads to the downregulation of mouse tert (mtert) transcription, as a TERT suppressor gene. Additionally, both human TERT (hTERT) and mouse TERT (mtert) promoter activity can be suppressed by PITX1. We showed that three and one binding sites, respectively, within the hTERT and mtert promoters that express a unique conserved region are responsible for the transcriptional activation of TERT. Furthermore, we showed that PITX1 binds to the TERT promoter both in vitro and in vivo. Thus, PITX1 suppresses TERT transcription through direct binding to the TERT promoter, which ultimately regulates telomerase activity. We transferred intact human chromosome 5 into mouse melanoma B16F10 cells by microcell fusion. The microcell hybrids (MH5) exhibited suppression of telomerase, we also obtained revertant clones (MH5R) in which telomerase is reactivated. To identify the differentially expressed genes on human chromosome 5, we performed expression microarray analysis using these two clones and parental B16F10 cells.

2010-09-10 | E-GEOD-23216 | biostudies-arrayexpress

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