36 research outputs found
Genome-wide mapping of i-motifs reveals their association with transcription regulation in live human cells
Lay Summary Among the secondary structures alternative to the DNA double helix, i-Motifs (iMs) and G-quadruplexes (G4s) are four-stranded non-canonical nucleic acid structures that form in cytosine- and guanine-rich regions, respectively. Because iMs fold in vitro under acidic conditions, they were long thought to form only in vitro. We now show that iMs, like G4s, form in live human cells mainly at gene promoters in open chromatin. iMs that are unstable in vitro still form in cells. iMs and G4s are cell-type specific and associated with increased transcription; however, transcript levels are remarkably different: low for iMs and high for G4s, indicating their distinct activity as regulators of the cell transcriptome. The iM/G4 interplay may represent a novel therapeutic target in disease.i-Motifs (iMs) are four-stranded DNA structures that form at cytosine (C)-rich sequences in acidic conditions in vitro. Their formation in cells is still under debate. We performed CUT & Tag sequencing using the anti-iM antibody iMab and showed that iMs form within the human genome in live cells. We mapped iMs in two human cell lines and recovered C-rich sequences that were confirmed to fold into iMs in vitro. We found that iMs in cells are mainly present at actively transcribing gene promoters, in open chromatin regions, they overlap with R-loops, and their abundance and distribution are specific to each cell type. iMs with both long and short C-tracts were recovered, further extending the relevance of iMs. By simultaneously mapping G-quadruplexes (G4s), which form at guanine-rich regions, and comparing the results with iMs, we proved that the two structures can form in independent regions; however, when both iMs and G4s are present in the same genomic tract, their formation is enhanced. iMs and G4s were mainly found at genes with low and high transcription rates, respectively. Our findings support the in vivo formation of iM structures and provide new insights into their interplay with G4s as new regulatory elements in the human genome
Mte1 interacts with Mph1 and promotes crossover recombination and telomere maintenance
Mph1 is a member of the conserved FANCM family of DNA motor proteins that play key roles in genome maintenance
processes underlying Fanconi anemia, a cancer predisposition syndrome in humans. Here, we identify Mte1
as a novel interactor of the Mph1 helicase in Saccharomyces cerevisiae. In vitro, Mte1 (Mph1-associated telomere
maintenance protein 1) binds directly to DNA with a preference for branched molecules such as D loops and fork
structures. In addition, Mte1 stimulates the helicase and fork regression activities of Mph1 while inhibiting the
ability of Mph1 to dissociate recombination intermediates. Deletion of MTE1 reduces crossover recombination and
suppresses the sensitivity of mph1Î mutant cells to replication stress. Mph1 and Mte1 interdependently colocalize
atDNAdamage-induced foci and dysfunctional telomeres, and MTE1 deletion results in elongated telomeres. Taken
together, our data indicate that Mte1 plays a role in regulation of crossover recombination, response to replication
stress, and telomere maintenance
Replication-Coupled DNA-Protein Crosslink Repair by SPRTN and the Proteasome in <i>Xenopus</i> Egg Extracts
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Tumor Necrosis Factor α Influences Phenotypic Plasticity and Promotes Epigenetic Changes in Human Basal Forebrain Cholinergic Neuroblasts.
TNFα is the main proinflammatory cytokine implicated in the pathogenesis of neurodegenerative disorders, but it also modulates physiological functions in both the developing and adult brain. In this study, we investigated a potential direct role of TNFα in determining phenotypic changes of a recently established cellular model of human basal forebrain cholinergic neuroblasts isolated from the nucleus basalis of Meynert (hfNBMs). Exposing hfNBMs to TNFα reduced the expression of immature markers, such as nestin and ÎČ-tubulin III, and inhibited primary cilium formation. On the contrary, TNFα increased the expression of TNFα receptor TNFR2 and the mature neuron marker MAP2, also promoting neurite elongation. Moreover, TNFα affected nerve growth factor receptor expression. We also found that TNFα induced the expression of DNA-methylation enzymes and, accordingly, downregulated genes involved in neuronal development through epigenetic mechanisms, as demonstrated by methylome analysis. In summary, TNFα showed a dual role on hfNBMs phenotypic plasticity, exerting a negative influence on neurogenesis despite a positive effect on differentiation, through mechanisms that remain to be elucidated. Our results help to clarify the complexity of TNFα effects in human neurons and suggest that manipulation of TNFα signaling could provide a potential therapeutic approach against neurodegenerative disorders
Arcobacter spp. in raw milk from vending machines in Piedmont and occurrence of virulence genes in isolates
Arcobacter spp. has been recognized as an emerging foodborne pathogen and a hazard to human health. In the dairy chain, it has been isolated from different sources, nevertheless data on Arcobacter occurrence in raw milk provided by vending machines are few. This study aimed to identify potentially pathogenic Arcobacter spp. in raw milk intended for human consumption sold through vending machines located in Piedmont. In an 8-month period, 37 raw milk samples were collected from 24 dairy farms: 12 (32,4%) were collected directly in farm from bulk tank milk and 25 (67,6%) from vending machines. Eight (21,6%) out of the 37 milk samples and 7 (29,2%) out of the 24 dairy farms were positive for Arcobacter spp. by culture examination. Four (16%) out of the 25 samples from vending machines and 4 (33,3%) out of the 12 samples from bulk tank milk were positive. All 8 isolates were identified as A. butzleri both by MALDI-TOF MS and multiplex end-point PCR. According to the detection of virulence genes, a total of four Patho-types were highlighted: 5 isolates in P-type 1 and only one isolate for each of the P-types 2-3-4. A. butzleri isolates carrying encoding virulence factors genes were isolated from raw milk intended for human consumption: these findings strengthen the compulsory consumption after boiling as required by current legislation and suggest the need of enlarging the analytical investigations to other microorganisms not yet included in the food safety criteria
Pediatric admissions to emergency departments of North-Western Italy during COVID-19 pandemic: A retrospective observational study
COVID-19 pandemic caused huge decrease of pediatric admissions to Emergency Department (ED), arising concerns about possible delays in diagnosis and treatment of severe disorders
New aspects of protein stability and turnover in the regulation of genome integrity:the role of Cmr1 and Rad56
A safe fix for alcohol-derived DNA damage:[Alcohol-derived DNA damage fixed in two ways]
Milano '60/'70: esperienze fuori contesto
L'itinerario curato dall'Ordine degli Architetti di Milano descrive una serie di opere architettoniche degli anni Sessanta e Settanta accomunabili per una tendenza a risultare interventi "fuori contesto", in differenti accezioni