Recently, the bone marrow (BM) has been shown to play a key role in regulating the survival and function of memory T cells. However, the impact of aging on these processes has not yet been studied. We demonstrate that the number of CD4+ and CD8+ T cells in the BM is maintained during aging. However, the composition of the T cell pool in the aged BM is altered with a decline of nave and an increase in effector-memory T cells. In contrast to the peripheral blood (PB), a highly activated CD8+CD28 T cell population, which lacks the late differentiation marker CD57, accumulates in the BM of elderly persons. IL-6 and IL-15, which are both increased in the aged BM, efficiently induce the activation, proliferation and differentiation of CD8+ T cell in vitro, highlighting a role of these cytokines in the age-dependent accumulation of highly activated CD8+CD28 T cells in the BM. Yet, these age-related changes do not impair the maintenance of a high number of polyfunctional memory CD4+ and CD8+ T cells in the BM of elderly persons. In summary, aging leads to the accumulation of a highly activated CD8+CD28 T cell population in the BM, which is driven by the age-related increase of IL-6 and IL-15. Despite these changes, the aged BM is a rich source of polyfunctional memory T cells and may thus represent an important line of defense to fight recurrent infections in old age.
The impact of aging on memory T cell phenotype and function in the human bone marrow.
Sex, Age
View SamplesAdministration of spermidine, a natural polyamine whose intracellular concentration declines during human ageing, markedly extends the lifespan of various model organisms including yeast, flies and worms. In ageing yeast, spermidine treatment triggeres epigenetic deacetylation of histone H3 through inhibition of histone acetyltransferases (HAT), leading to induction of autophagy and thereby suppressing oxidative stress and necrosis. In order to further characterize the effects by spermidine supplementation of aging yeast cultures and to understand how global histone deacetylation affects gene transcription during aging, Affymetrix-based microarray analyses of three day old as well as ten day old cultures with and without administration of spermidine was performed.
Induction of autophagy by spermidine promotes longevity.
Age, Compound, Time
View SamplesHuman transcripts can typically be processed at multiple polyadenylation sites to yield mRNA isoforms with distinct 3 ends. A multitude of factors contributes to the choice of individual polyadenylation sites in different cell types and tissues. In this study we have found that the heterogenous ribonucleoprotein C (hnRNP C), an RNA binding protein that was previously linked to splicing and polyadenylation at Alu repeat elements, is a general regulator of pre-mRNA cleavage and polyadenylation. By sequencing mRNA 3 ends from cells expressing normal and reduced levels of hnRNP C we found that transcripts that contain poly(U) tracts around their poly(A) sites respond in a manner indicative of hnRNP C repressing cleavage and polyadenylation. The 3 UTR isoforms whose abundance is modulated by hnRNP C contain U-rich elements and can thereby interact with A/U-rich element binding proteins that have been shown to alter transcript stability, sub-cellular localization and even the localization of the translated proteins.
A comprehensive analysis of 3' end sequencing data sets reveals novel polyadenylation signals and the repressive role of heterogeneous ribonucleoprotein C on cleavage and polyadenylation.
No sample metadata fields
View SamplesTranscriptional analysis of the effects of the deletion of the sRNAs glmY and glmZ in EHEC
Global analysis of posttranscriptional regulation by GlmY and GlmZ in enterohemorrhagic Escherichia coli O157:H7.
No sample metadata fields
View SamplesThe adult pancreas is capable of limited regeneration after injury, but has no defined stem cell population. The cell types and molecular signals that govern the production of new pancreatic tissue are not well understood. Here we show that inactivation of the SCF-type E3 ubiquitin ligase substrate recognition component Fbw7 induces pancreatic ductal cells to reprogram into -cells. The induced -cells resemble islet -cells in morphology and histology, express genes essential for -cell function, and release insulin upon glucose challenge. Thus, loss of Fbw7 appears to reawaken an endocrine developmental differentiation program in adult pancreatic ductal cells. Our study highlights the plasticity of seemingly differentiated adult cells, identifies Fbw7 as a master regulator of cell fate decisions in the pancreas, and reveals adult pancreatic duct cells as a latent multipotent cell type.
Loss of Fbw7 reprograms adult pancreatic ductal cells into α, δ, and β cells.
Specimen part, Treatment
View SamplesIn eukaryotes, the 3'' ends of RNA polymerase II-generated transcripts are made in the majority of cases by site-specific endonucleolytic cleavage, followed by the addition of a poly(A) tail. By alternative polyadenylation, a gene can give rise to multiple mRNA isoforms that differ in the length of their 3'' UTRs and hence in their susceptibility to post-transcriptional regulatory factors such as microRNAs. A series of recently conducted high-throughput studies of poly(A) site usage revealed an extensive tissue-specific control of 3’ UTR length and drastic changes in 3’ UTR length of mRNAs upon induction of proliferation in resting cells. To understand the dynamics of polyadenylation site usage, we recently identified binding sites of the major pre-mRNA 3’ end processing factors - cleavage and polyadenylation specificity factor (CPSF), cleavage stimulation factor (CstF), and cleavage factor Im (CF Im) - and mapped cleaved polyadenylation sites in HEK293 cells. Our present study extends previous findings on the role of CF Im in alternative polyadenylation and reveals that subunits of the CF Im complex generally control 3’ UTR length. More specifically, we demonstrate that the loss-of-function of CF Im68 and CF Im25 but not of CF Im59 leads to a transcriptome-wide increase of the use of proximal polyadenylation sites. Overall design: 3'' ends of transcripts were profiled by high-throughput sequencing in HEK 293 cells under normal conditions, and in HEK 293 cells depleted of 3'' end processing factors CF Im25, CF Im59, and CF Im68.
Cleavage factor Im is a key regulator of 3' UTR length.
Cell line, Subject
View SamplesThe RNA helicase UPF1 is best known for its key function in mRNA nonsense-mediated mRNA decay (NMD), but has also been implicated in additional mRNA turnover mechanisms, telomere homeostasis, and DNA replication. In NMD, UPF1 recruitment to target mRNAs is thought to occur through interaction with release factors at terminating ribosomes, but evidence for translation-independent interaction of UPF1 with the 3’ untranslated region (UTR) of mRNAs has also been reported. To map UPF1 binding sites transcriptome-wide, we performed individual-nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP) in human cells, untreated or after inhibiting translation by puromycin. We found a strong association of UPF1 with 3’ UTRs in undisturbed, translationally active cells and a significant increase in UPF1 binding to coding sequence (CDS) after translation inhibition. These results indicate that UPF1 binds RNA before translation and gets displaced from the CDS by translating ribosomes. This evidence for translation-independent UPF1-RNA interaction, which is corroborated by RNA immunoprecipitations experiments and by our observation that UPF1 also crosslinks to long non-coding RNAs, suggests that the decision to trigger NMD occurs after association of UPF1 with the mRNA, presumably through activation of RNA-bound UPF1 by aberrant translation termination. Overall design: Examination of Upf1 binding preferences via iCLIP in untreated HeLa cells and HeLa cells, where translation is blocked by puromycin treatment in vivo crosslinking and immunoprecipitation strategy (iCLIP)
Translation-dependent displacement of UPF1 from coding sequences causes its enrichment in 3' UTRs.
Cell line, Subject
View SamplesThrough alternative polyadenylation, human mRNAs acquire longer or shorter 3'' untranslated regions, the latter typically associated with higher transcript stability and increased protein production. To understand the dynamics of polyadenylation site usage, we mapped transcriptome-wide both binding sites of 3'' end processing factors CPSF-160, CPSF-100, CPSF-73, CPSF-30, Fip1, CstF-64, CstF-64tau, CF Im25, CF Im59, and CF Im68 and 3'' end processing sites in HEK293 cells. We found that although binding sites of these factors generally cluster around the poly(A) sites most frequently used in cleavage, CstF-64/CstF-64tau and CF Im proteins have much higher positional specificity compared to CPSF components. Knockdown of CF Im68 induced a systematic use of proximal polyadenylation sites, indicating that changes in relative abundance of a single 3'' end processing factor can modulate the length of 3'' untranslated regions transcriptome-wide, and suggesting a mechanism behind the previously observed increase in tumor cell invasiveness upon CF Im68 knockdown. Overall design: 3'' ends of transcripts were profiled by high-throughput sequencing in HEK 293 cells under normal conditions, and in HEK 293 cells depleted of 3'' end processing factors CF Im 68 and CstF-64.
Genome-wide analysis of pre-mRNA 3' end processing reveals a decisive role of human cleavage factor I in the regulation of 3' UTR length.
Cell line, Subject
View SamplesBacterial pathogens must be able to both recognize suitable niches within the host for colonization and successfully compete with commensal flora for nutrients in order to establish infection. Ethanolamine (EA) is a major component of mammalian and bacterial membranes and may be used by pathogens as a carbon and/or nitrogen source in the gastrointestinal tract. We examined how EA influences gene expression in the human pathogen enterohemorrhagic Escherichia coli O157:H7 (EHEC). Our results indicate EA is not only important for nitrogen metabolism, but that EA is used in cell-to-cell signaling to activate virulence gene expression. Genes encoding for the global regulatory proteins QseC, QseE, and QseA, as well as for attaching and effacement (AE) lesion formation and Shiga toxin are differentially regulated when EHEC is grown with micromolar concentrations of EA. We also constructed a deletion of eutR that encodes the regulator of the eut (EA utilization) operon and examined virulence gene expression. These results suggest that EutR is important in regulating gene expression in response to EA, but that EA signaling does not occur solely through EutR. This is the first report linking EA to cell-to-cell signaling and pathogenesis.
Ethanolamine controls expression of genes encoding components involved in interkingdom signaling and virulence in enterohemorrhagic Escherichia coli O157:H7.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Ars2 promotes proper replication-dependent histone mRNA 3' end formation.
Specimen part, Cell line, Treatment
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