VID22 counteracts G-quadruplex-induced genome instability

Genome instability is a condition characterized by the accumulation of genetic alterations and is a hallmark of cancer cells. To uncover new genes and cellular pathways affecting endogenous DNA damage and genome integrity, we exploited a Synthetic Genetic Array (SGA)-based screen in yeast. Among the positive genes, we identified VID22, reported to be involved in DNA double-strand break repair. vid22Δ cells exhibit increased levels of endogenous DNA damage, chronic DNA damage response activation and accumulate DNA aberrations in sequences displaying high probabilities of forming G-quadruplexes (G4-DNA). If not resolved, these DNA secondary structures can block the progression of both DNA and RNA polymerases and correlate with chromosome fragile sites. Vid22 binds to and protects DNA at G4-containing regions both in vitro and in vivo. Loss of VID22 causes an increase in gross chromosomal rearrangement (GCR) events dependent on G-quadruplex forming sequences. Moreover, the absence of Vid22 causes defects in the correct maintenance of G4-DNA rich elements, such as telomeres and mtDNA, and hypersensitivity to the G4-stabilizing ligand TMPyP4. We thus propose that Vid22 is directly involved in genome integrity maintenance as a novel regulator of G4 metabolism.Associazione Italiana per la Ricerca sul Cancro (AIRC) 15631, 21806MIUR PRIN 2015- 2015SJLMB9, PRIN 2017-2017KSZZJW, PRIN2017-2017Z55KCMinisterio de Economía y Competitividad BFU2016- 75058-PCanadian Institutes of Health Research FDN-15991

Nanopore ReCappable sequencing maps SARS-CoV-2 5′ capping sites and provides new insights into the structure of sgRNAs

The SARS-CoV-2 virus has a complex transcriptome characterised by multiple, nested subgenomic RNAsused to express structural and accessory proteins. Long-read sequencing technologies such as nanopore direct RNA sequencing can recover full-length transcripts, greatly simplifying the assembly of structurally complex RNAs. However, these techniques do not detect the 5 ' cap, thus preventing reliable identification and quantification of full-length, coding transcript models. Here we used Nanopore ReCappable Sequencing (NRCeq), a new technique that can identify capped full-length RNAs, to assemble a complete annotation of SARS-CoV-2 sgRNAs and annotate the location of capping sites across the viral genome. We obtained robust estimates of sgRNA expression across cell lines and viral isolates and identified novel canonical and non-canonical sgRNAs, including one that uses a previously un-annotated leader-to-body junction site. The data generated in this work constitute a useful resource for the scientific community and provide important insights into the mechanisms that regulate the transcription of SARS-CoV-2 sgRNAs

VID22 counteracts G-quadruplex-induced genome instability

Genome instability is a condition characterized by the accumulation of genetic alterations and is a hallmark of cancer cells. To uncover new genes and cellular pathways affecting endogenous DNA damage and genome integrity, we exploited a Synthetic Genetic Array (SGA)-based screen in yeast. Among the positive genes, we identified VID22, reported to be involved in DNA double-strand break repair. vid22Δ cells exhibit increased levels of endogenous DNA damage, chronic DNA damage response activation and accumulate DNA aberrations in sequences displaying high probabilities of forming G-quadruplexes (G4-DNA). If not resolved, these DNA secondary structures can block the progression of both DNA and RNA polymerases and correlate with chromosome fragile sites. Vid22 binds to and protects DNA at G4-containing regions both in vitro and in vivo. Loss of VID22 causes an increase in gross chromosomal rearrangement (GCR) events dependent on G-quadruplex forming sequences. Moreover, the absence of Vid22 causes defects in the correct maintenance of G4-DNA rich elements, such as telomeres and mtDNA, and hypersensitivity to the G4-stabilizing ligand TMPyP4. We thus propose that Vid22 is directly involved in genome integrity maintenance as a novel regulator of G4 metabolism

EPIGENETIC ALTERATIONS INDUCED BY THE PML-RAR ONCOGENE DURING THE TRANSFORMATION PROCESS OF ITS TARGET CELLS

Acute promyelocytic leukaemia (APL) is a subtype of acute myeloid leukaemia, caused by the t(15;17) translocation that generates an aberrant transcription factor PML-RAR\u3b1. Owing to its ability to affect gene expression through chromatin modifications, PML-RAR\u3b1 is potentially capable of a multitude of alterations in the chromatin landscape, most of which are still poorly characterized. To investigate PML-RAR\u3b1 mechanistical activity at early stages of tumor initiation, first we started elucidating the target cell(s) in which the leukemogenesis takes place. Our results showed that phenotypically defined common myeloid progenitor hematopoietic (CMPs), are capable of initiating leukemogenesis. We found that PML-RAR\u3b1 can induce an adult stem cell signature in normal myeloid progenitors, distinct from that observed in frankly established leukemic stem cells. Among the transcriptional targets identified, the cell cycle inhibitor p21, required for self-renewal of normal and leukemic stem cells, was shown to be indispensable for this phenomenon. To mechanistically dissect the pre-leukemic epigenome of the identified hematopoietic subpopulation, we developed ad hoc technological approaches to study small population of cells (miniChIP-sequencing, Nuclease Accessible Site Sequencing and DNA methylation sequencing). The analysis of the changes between chromatin states show that the oncogene in the pre-leukemic state does not impose a global alteration of chromatin but, rather, it functions as a local modulator of chromatin accessibility involving genomic regions enriched in important regulators of normal and aberrant hematopoiesis

Escritura de contrata para el suministro de mil toneladas de carbón Cardiff necesarias en este Arsenal, adjudicada á favor de Don Demetrio Plá y Frige, 1889

Texto datado en Ferrol, 1889Texto fechado en Ferrol, 188

Longitudinal optical coherence tomography indices in idiopathic intracranial hypertension

Abstract Idiopathic intracranial hypertension (IIH) may result in optic nerve fiber loss and even atrophy. The timing of the optical coherence tomography (OCT) indices reaching the lowest point (nadir) and the factors that predict the patient's anatomical outcome are not known. We aimed to determine the timing and the factors that affect nadir retinal nerve fiber layer (RNFL) thickness. The medical records of 99 IIH patients who were treated from December 2009 to January 2020 were retrospectively reviewed. The mean RNFL thickness at presentation was 263.5 ± 106.4 µm. The mean time to nadir was 7.9 ± 6.3 months. The average RNFL and ganglion cell complex (GCC) thickness at the nadir were 92.6 ± 14.5 µm (47% showed thinning) and 77.9 ± 27.8 µm (70% showed thinning), respectively. The Frisén disc edema stage and average RNFL thickness at baseline correlated with a longer time to nadir, (r = 0.28 P = 0.003 and r = 0.24, P = 0.012, respectively). The nadir average RNFL thickness and the nadir average GCC thickness (r = 0.32, P = 0.001, r = 0.29, P = 0.002, respectively) correlated with the baseline visual field mean deviation. The final anatomical outcome of IIH episodes in this study resulted in RNFL and GCC thinning. The time to RNFL nadir and its values correlated with IIH severity at presentation