Project description:Expression profile of human GEP-NET tumors, including 113 fresh frozen biopsies of primary and metastatic tumours originating from pancreas (P-NET, 83 primary and 30 metastasis), 81 from small intestine (SI-NET, 44 primary and 37 metastasis), and 18 from rectum (RE-NET, 3 primary and 15 metastasis).
Project description:While strongly implicated in Postural Tachycardia Syndrome (POTS), considerable controversy exists regarding norepinephrine transporter (NET) loss-of-function. POTS is characterized by the clinical symptoms of orthostatic intolerance, light-headedness, tachycardia and syncope or near syncope with upright posture. Abnormal sympathetic nervous system activity is typical, of a type which suggests dysfunction of the NET, with evidence the gene responsible is under tight epigenetic control. Using RNA of isolated chromatin combined with sequencing (RICh-Seq) we show let7i miRNA suppresses NET by MeCP2. Vorinostat restores epigenetic control and NET expression in POTS.
Project description:Genome wide DNA methylation profiling of hereditary and sporadic NET using GPL21145 Bisulphite converted DNA from 96 samples were hybridised to the Illumina Infinium Epic Human Methylation Beadchip
Project description:Transcription by RNA polymerase (RNAP) is interrupted by pauses that play diverse regulatory roles. Although individual pauses have been studied in vitro, the determinants of pauses in vivo and their distribution throughout the bacterial genome remain unknown. Using nascent transcript sequencing we identify a 16 nt consensus pause sequence in E. coli that accounts for known regulatory pause sites as well as ~20,000 new in vivo pause sites. In vitro single-molecule and ensemble analyses demonstrate that these pauses result from RNAP/nucleic-acid interactions that inhibit next-nucleotide addition. The consensus sequence also leads to pausing by RNAPs from diverse lineages and is enriched at translation start sites in both E. coli and B. subtilis. Our results thus implicate a conserved mechanism unifying known and newly identified pause events. Examination of nascent transcripts in E. coli and B. subtilis. 6 samples of E. coli NET-seq, 1 sample of E. coli mRNA-seq, and 1 sample of B. subtilis NET-seq.
Project description:Transcriptional pausing aids gene regulation by cellular RNA polymerases (RNAPs). In many bacteria, a surface-exposed domain inserted into the catalytic trigger loop (TL) of RNAP, called SI3 in Escherichia coli, modulates pausing and is essential for growth. Here we describe a viable E. coli strain lacking SI3 enabled by a suppressor TL substitution (β'Ala941→Thr; ∆SI3*). ∆SI3* increased transcription rate in vitro relative to ∆SI3, possibly explaining its viability, but retained both positive and negative effects of ∆SI3 on pausing. ∆SI3* inhibited pauses stabilized by nascent RNA structures (pause hairpins; PHs) but enhanced other pauses. Using NET-seq, we found that ∆SI3*-enhanced pauses resemble the consensus elemental pause sequence whereas sequences at ∆SI3*-suppressed pauses, which exhibited greater association with PHs, were more divergent. ∆SI3*-suppressed pauses also were associated with apparent pausing one nt upstream from the consensus sequence, often generating tandem pause sites. These '–2 pauses' were stimulated by pyrophosphate in vitro and by addition of apyrase to degrade residual NTPs during NET-seq sample processing. We propose that some pauses are readily reversible by pyrophosphorolysis or single-nucleotide cleavage. Our results document multiple ways that SI3 modulates pausing in vivo and may explain discrepancies in consensus pause sequences in some NET-seq studies.
Project description:Neutrophil extracellular traps (NET) formation is part of the neutrophil response to infections, but excessive or inappropriate NETosis may trigger the production of autoantibodies and cause organ damage in autoimmune disorders. Spontaneously netting neutrophils are not frequent and induction of NET in vitro by selected stimuli is necessary to investigate their structure. In the present work, the protein composition and post-translational modifications of NET produced under different stimuli is studied by means of proteomic analysis. Neutrophils from healthy donors were stimulated by PMA, A23187, E.Coli LPS or untreated; after 3 hours cells were washed, treated with DNase and supernatants collected for mass spectrometry. Data were analyzed by unsupervised hierarchical clustering analyses. We identified proteins contained in NETs of any source or exclusive of one stimulus: LPS-induced and spontaneous NET diverge in protein composition, while PMA- and A23187-induced NET appear more similar. Among the post-translational modifications we examined, methionine sulfoxidation is frequent especially in PMA- and LPS-induced NETs. Myeloperoxidase is the protein more extensively modified. Thus, proteomic analysis indicates that NETs induced by different stimuli are heterogeneous in terms of both protein composition and post-translational modifications, suggesting that NET induced in different conditions may have different biological effects.
Project description:The advent of quantitative approaches that enable interrogation of transcription at single nucleotide resolution has allowed a novel understanding of transcriptional regulation previously undefined. To better map transcription genome-wide at base pair resolution and with transcription/elongation factor dependency we developed an adapted NET-seq protocol called NET-prism (Native Elongating Transcription by Polymerase-Regulated Immunoprecipitants in the Mammalian genome). NET-prism introduces an immunoprecipitation to capture RNA Pol II – associated proteins, which reveals the interaction of these proteins with active RNA Pol II. Application of NET-prism on different Pol II variants (Pol II S2ph, Pol II S5ph), elongation factors (Spt6, Ssrp1), splicing factors (Sf1), and components of the pre-initiation complex (PIC) (TFIID, and Mediator) reveals diverse Pol II signals, at a single nucleotide resolution, with regards to directionality and intensity over promoters, splice sites, and enhancers/super-enhancers. NET-prism will be broadly applicable as it exposes transcription factor/Pol II dependent topographic specificity and thus, a new degree of regulatory complexity.