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1.
Nature ; 595(7869): 713-717, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34192736

RESUMO

After the first wave of SARS-CoV-2 infections in spring 2020, Europe experienced a resurgence of the virus starting in late summer 2020 that was deadlier and more difficult to contain1. Relaxed intervention measures and summer travel have been implicated as drivers of the second wave2. Here we build a phylogeographical model to evaluate how newly introduced lineages, as opposed to the rekindling of persistent lineages, contributed to the resurgence of COVID-19 in Europe. We inform this model using genomic, mobility and epidemiological data from 10 European countries and estimate that in many countries more than half of the lineages circulating in late summer resulted from new introductions since 15 June 2020. The success in onward transmission of newly introduced lineages was negatively associated with the local incidence of COVID-19 during this period. The pervasive spread of variants in summer 2020 highlights the threat of viral dissemination when restrictions are lifted, and this needs to be carefully considered in strategies to control the current spread of variants that are more transmissible and/or evade immunity. Our findings indicate that more effective and coordinated measures are required to contain the spread through cross-border travel even as vaccination is reducing disease burden.


Assuntos
COVID-19/transmissão , COVID-19/virologia , SARS-CoV-2/isolamento & purificação , COVID-19/epidemiologia , COVID-19/prevenção & controle , Europa (Continente)/epidemiologia , Genoma Viral/genética , Humanos , Incidência , Locomoção , Filogenia , Filogeografia , SARS-CoV-2/classificação , SARS-CoV-2/genética , SARS-CoV-2/patogenicidade , Fatores de Tempo , Viagem/estatística & dados numéricos
2.
PLoS Pathog ; 19(4): e1011348, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-37071654

RESUMO

Since the latter part of 2020, SARS-CoV-2 evolution has been characterised by the emergence of viral variants associated with distinct biological characteristics. While the main research focus has centred on the ability of new variants to increase in frequency and impact the effective reproductive number of the virus, less attention has been placed on their relative ability to establish transmission chains and to spread through a geographic area. Here, we describe a phylogeographic approach to estimate and compare the introduction and dispersal dynamics of the main SARS-CoV-2 variants - Alpha, Iota, Delta, and Omicron - that circulated in the New York City area between 2020 and 2022. Notably, our results indicate that Delta had a lower ability to establish sustained transmission chains in the NYC area and that Omicron (BA.1) was the variant fastest to disseminate across the study area. The analytical approach presented here complements non-spatially-explicit analytical approaches that seek a better understanding of the epidemiological differences that exist among successive SARS-CoV-2 variants of concern.


Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , COVID-19/virologia , Cidade de Nova Iorque/epidemiologia , SARS-CoV-2/genética
3.
J Med Virol ; 96(7): e29773, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38940448

RESUMO

The dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission are influenced by a variety of factors, including social restrictions and the emergence of distinct variants. In this study, we delve into the origins and dissemination of the Alpha, Delta, and Omicron-BA.1 variants of concern in Galicia, northwest Spain. For this, we leveraged genomic data collected by the EPICOVIGAL Consortium and from the GISAID database, along with mobility information from other Spanish regions and foreign countries. Our analysis indicates that initial introductions during the Alpha phase were predominantly from other Spanish regions and France. However, as the pandemic progressed, introductions from Portugal and the United States became increasingly significant. The number of detected introductions varied from 96 and 101 for Alpha and Delta to 39 for Omicron-BA.1. Most of these introductions left a low number of descendants (<10), suggesting a limited impact on the evolution of the pandemic in Galicia. Notably, Galicia's major coastal cities emerged as critical hubs for viral transmission, highlighting their role in sustaining and spreading the virus. This research emphasizes the critical role of regional connectivity in the spread of SARS-CoV-2 and offers essential insights for enhancing public health strategies and surveillance measures.


Assuntos
COVID-19 , SARS-CoV-2 , Espanha/epidemiologia , COVID-19/epidemiologia , COVID-19/transmissão , COVID-19/virologia , Humanos , SARS-CoV-2/genética , Genoma Viral , Filogenia , Pandemias
4.
PLoS Pathog ; 17(5): e1009571, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34015049

RESUMO

During the first phase of the COVID-19 epidemic, New York City rapidly became the epicenter of the pandemic in the United States. While molecular phylogenetic analyses have previously highlighted multiple introductions and a period of cryptic community transmission within New York City, little is known about the circulation of SARS-CoV-2 within and among its boroughs. We here perform phylogeographic investigations to gain insights into the circulation of viral lineages during the first months of the New York City outbreak. Our analyses describe the dispersal dynamics of viral lineages at the state and city levels, illustrating that peripheral samples likely correspond to distinct dispersal events originating from the main metropolitan city areas. In line with the high prevalence recorded in this area, our results highlight the relatively important role of the borough of Queens as a transmission hub associated with higher local circulation and dispersal of viral lineages toward the surrounding boroughs.


Assuntos
COVID-19/epidemiologia , COVID-19/transmissão , SARS-CoV-2/genética , Genoma Viral/genética , Humanos , Cidade de Nova Iorque/epidemiologia , Filogenia , Filogeografia , Prevalência , SARS-CoV-2/classificação , SARS-CoV-2/isolamento & purificação
5.
Proc Natl Acad Sci U S A ; 117(33): 20004-20014, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32747568

RESUMO

KRAS, NRAS, and BRAF mutations which activate p44/42 mitogen-activated protein kinase (MAPK) signaling are found in half of myeloma patients and contribute to proteasome inhibitor (PI) resistance, but the underlying mechanisms are not fully understood. We established myeloma cell lines expressing wild-type (WT), constitutively active (CA) (G12V/G13D/Q61H), or dominant-negative (DN) (S17N)-KRAS and -NRAS, or BRAF-V600E. Cells expressing CA mutants showed increased proteasome maturation protein (POMP) and nuclear factor (erythroid-derived 2)-like 2 (NRF2) expression. This correlated with an increase in catalytically active proteasome subunit ß (PSMB)-8, PSMB9, and PSMB10, which occurred in an ETS transcription factor-dependent manner. Proteasome chymotrypsin-like, trypsin-like, and caspase-like activities were increased, and this enhanced capacity reduced PI sensitivity, while DN-KRAS and DN-NRAS did the opposite. Pharmacologic RAF or MAPK kinase (MEK) inhibitors decreased proteasome activity, and sensitized myeloma cells to PIs. CA-KRAS, CA-NRAS, and CA-BRAF down-regulated expression of endoplasmic reticulum (ER) stress proteins, and reduced unfolded protein response activation, while DN mutations increased both. Finally, a bortezomib (BTZ)/MEK inhibitor combination showed enhanced activity in vivo specifically in CA-NRAS models. Taken together, the data support the hypothesis that activating MAPK pathway mutations enhance PI resistance by increasing proteasome capacity, and provide a rationale for targeting such patients with PI/RAF or PI/MEK inhibitor combinations. Moreover, they argue these mutations promote myeloma survival by reducing cellular stress, thereby distancing plasma cells from the apoptotic threshold, potentially explaining their high frequency in myeloma.


Assuntos
Estresse do Retículo Endoplasmático , GTP Fosfo-Hidrolases/metabolismo , Proteínas de Membrana/metabolismo , Mieloma Múltiplo/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Proto-Oncogênicas B-raf/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Apoptose/efeitos dos fármacos , Bortezomib/farmacologia , Estresse do Retículo Endoplasmático/efeitos dos fármacos , GTP Fosfo-Hidrolases/genética , Humanos , Proteínas de Membrana/genética , Mieloma Múltiplo/genética , Mieloma Múltiplo/fisiopatologia , Mutação , Complexo de Endopeptidases do Proteassoma/genética , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas p21(ras)/genética
6.
Euro Surveill ; 28(45)2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37943503

RESUMO

BackgroundThe earliest recognised infections by the SARS-CoV-2 Omicron variant (Pango lineage B.1.1.529) in Belgium and Switzerland suggested a connection to an international water polo tournament, held 12-14 November 2021 in Brno, Czechia.AimTo study the arrival and subsequent spread of the Omicron variant in Belgium and Switzerland, and understand the overall importance of this international sporting event on the number of infections in the two countries.MethodsWe performed intensive forward and backward contact tracing in both countries, supplemented by phylogenetic investigations using virus sequences of the suspected infection chain archived in public databases.ResultsThrough contact tracing, we identified two and one infected athletes of the Belgian and Swiss water polo teams, respectively, and subsequently also three athletes from Germany. In Belgium and Switzerland, four and three secondary infections, and three and one confirmed tertiary infections were identified. Phylogenetic investigation demonstrated that this sporting event played a role as the source of infection, but without a direct link with infections from South Africa and not as a superspreading event; the virus was found to already be circulating at that time in the countries involved.ConclusionThe SARS-CoV-2 Omicron variant started to circulate in Europe several weeks before its identification in South Africa on 24 November 2021. Accordingly, it can be assumed that travel restrictions are usually implemented too late to prevent the spread of newly detected SARS-CoV-2 variants to other regions. Phylogenetic analysis may modify the perception of an apparently clear result of intensive contact tracing.


Assuntos
COVID-19 , Esportes Aquáticos , Humanos , SARS-CoV-2/genética , Bélgica/epidemiologia , Suíça/epidemiologia , República Tcheca , Filogenia , COVID-19/epidemiologia , Alemanha
7.
Mol Biol Evol ; 38(4): 1608-1613, 2021 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-33316043

RESUMO

Since the start of the COVID-19 pandemic, an unprecedented number of genomic sequences of SARS-CoV-2 have been generated and shared with the scientific community. The unparalleled volume of available genetic data presents a unique opportunity to gain real-time insights into the virus transmission during the pandemic, but also a daunting computational hurdle if analyzed with gold-standard phylogeographic approaches. To tackle this practical limitation, we here describe and apply a rapid analytical pipeline to analyze the spatiotemporal dispersal history and dynamics of SARS-CoV-2 lineages. As a proof of concept, we focus on the Belgian epidemic, which has had one of the highest spatial densities of available SARS-CoV-2 genomes. Our pipeline has the potential to be quickly applied to other countries or regions, with key benefits in complementing epidemiological analyses in assessing the impact of intervention measures or their progressive easement.


Assuntos
COVID-19/transmissão , COVID-19/virologia , Genoma Viral , Filogeografia , SARS-CoV-2/genética , Bélgica , COVID-19/epidemiologia , Evolução Molecular , Genômica , Humanos , Funções Verossimilhança , Mutação , Isolamento de Pacientes , Filogenia , Distanciamento Físico , Análise Espaço-Temporal , Fluxo de Trabalho
8.
Adv Exp Med Biol ; 1389: 295-315, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36350515

RESUMO

The modification of DNA bases is a classic hallmark of epigenetics. Four forms of modified cytosine-5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine-have been discovered in eukaryotic DNA. In addition to cytosine carbon-5 modifications, cytosine and adenine methylated in the exocyclic amine-N4-methylcytosine and N6-methyladenine-are other modified DNA bases discovered even earlier. Each modified base can be considered a distinct epigenetic signal with broader biological implications beyond simple chemical changes. Since 1994, several crystal structures of proteins and enzymes involved in writing, reading, and erasing modified bases have become available. Here, we present a structural synopsis of writers, readers, and erasers of the modified bases from prokaryotes and eukaryotes. Despite significant differences in structures and functions, they are remarkably similar regarding their engagement in flipping a target base/nucleotide within DNA for specific recognitions and/or reactions. We thus highlight base flipping as a common structural framework broadly applied by distinct classes of proteins and enzymes across phyla for epigenetic regulations of DNA.


Assuntos
5-Metilcitosina , Metilação de DNA , DNA , 5-Metilcitosina/química , Citosina/química , DNA/metabolismo , Epigênese Genética , Eucariotos/genética , Eucariotos/metabolismo
9.
Proc Natl Acad Sci U S A ; 115(44): 11226-11231, 2018 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30262649

RESUMO

Accurate translation of the genetic code is critical to ensure expression of proteins with correct amino acid sequences. Certain tRNAs can cause a shift out of frame (i.e., frameshifting) due to imbalances in tRNA concentrations, lack of tRNA modifications or insertions or deletions in tRNAs (called frameshift suppressors). Here, we determined the structural basis for how frameshift-suppressor tRNASufA6 (a derivative of tRNAPro) reprograms the mRNA frame to translate a 4-nt codon when bound to the bacterial ribosome. After decoding at the aminoacyl (A) site, the crystal structure of the anticodon stem-loop of tRNASufA6 bound in the peptidyl (P) site reveals ASL conformational changes that allow for recoding into the +1 mRNA frame. Furthermore, a crystal structure of full-length tRNASufA6 programmed in the P site shows extensive conformational rearrangements of the 30S head and body domains similar to what is observed in a translocation intermediate state containing elongation factor G (EF-G). The 30S movement positions tRNASufA6 toward the 30S exit (E) site disrupting key 16S rRNA-mRNA interactions that typically define the mRNA frame. In summary, this tRNA-induced 30S domain change in the absence of EF-G causes the ribosome to lose its grip on the mRNA and uncouples the canonical forward movement of the tRNAs during elongation.


Assuntos
Mutação da Fase de Leitura/genética , Mudança da Fase de Leitura do Gene Ribossômico/genética , RNA de Transferência/genética , Ribossomos/genética , Bactérias/genética , Códon/genética , Fator G para Elongação de Peptídeos/genética , Biossíntese de Proteínas/genética , RNA Mensageiro/genética , RNA Ribossômico 16S/genética , Fases de Leitura/genética
10.
Emerg Infect Dis ; 26(12): 3034-3038, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33219795

RESUMO

Multidrug-resistant Salmonella enterica subspecies enterica 4,[5],12:i:- sequence type 34 represents a worldwide public health risk. To determine its origin in the United States, we reconstructed a time-scaled phylogeny with a discrete trait geospatial model. The clone in the United States was introduced from Europe on multiple occasions in the early 2000s.


Assuntos
Salmonelose Animal , Salmonella enterica , Animais , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Europa (Continente)/epidemiologia , Testes de Sensibilidade Microbiana , Salmonella enterica/genética , Estados Unidos/epidemiologia
11.
Artigo em Inglês | MEDLINE | ID: mdl-30745386

RESUMO

Nontyphoidal Salmonella enterica (NTS) poses a major public health risk worldwide that is amplified by the existence of antimicrobial-resistant strains, especially those resistant to quinolones and extended-spectrum cephalosporins (ESC). Little is known on the dissemination of plasmids harboring the acquired genetic determinants that confer resistance to these antimicrobials across NTS serotypes from livestock in the United States. NTS isolates (n = 183) from U.S. swine clinical cases retrieved during 2014 to 2016 were selected for sequencing based on their phenotypic resistance to enrofloxacin (quinolone) or ceftiofur (3rd-generation cephalosporin). De novo assemblies were used to identify chromosomal mutations and acquired antimicrobial resistance genes (AARGs). In addition, plasmids harboring AARGs were identified using short-read assemblies and characterized using a multistep approach that was validated by long-read sequencing. AARGs to quinolones [qnrB15, qnrB19, qnrB2, qnrD, qnrS1, qnrS2, and aac(6')Ib-cr] and ESC (blaCMY-2, blaCTX-M-1, blaCTX-M-27, and blaSHV-12) were distributed across serotypes and were harbored by several plasmids. In addition, chromosomal mutations associated with resistance to quinolones were identified in the target enzyme and efflux pump regulation genes. The predominant plasmid harboring the prevalent qnrB19 gene was distributed across serotypes. It was identical to a plasmid previously reported in S. enterica serovar Anatum from swine in the United States (GenBank accession number KY991369.1) and similar to Escherichia coli plasmids from humans in South America (GenBank accession numbers GQ374157.1 and JN979787.1). Our findings suggest that plasmids harboring AARGs encoding mechanisms of resistance to critically important antimicrobials are present in multiple NTS serotypes circulating in swine in the United States and can contribute to resistance expansion through horizontal transmission.


Assuntos
Resistência às Cefalosporinas/genética , Cefalosporinas/farmacologia , Plasmídeos/genética , Quinolonas/farmacologia , Salmonella enterica/genética , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla/genética , Enrofloxacina/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Testes de Sensibilidade Microbiana/métodos , Salmonella enterica/efeitos dos fármacos , Sorogrupo , América do Sul , Suínos , Estados Unidos
12.
J Immunol ; 199(3): 1069-1085, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28687659

RESUMO

Inflammatory processes play a key role in pathophysiology of many neurologic diseases/trauma, but the effect of immune cells and factors on neurotransplantation strategies remains unclear. We hypothesized that cellular and humoral components of innate immunity alter fate and migration of human neural stem cells (hNSC). In these experiments, conditioned media collected from polymorphonuclear leukocytes (PMN) selectively increased hNSC astrogliogenesis and promoted cell migration in vitro. PMN were shown to generate C1q and C3a; exposure of hNSC to PMN-synthesized concentrations of these complement proteins promoted astrogliogenesis and cell migration. Furthermore, in vitro, Abs directed against C1q and C3a reversed the fate and migration effects observed. In a proof-of-concept in vivo experiment, blockade of C1q and C3a transiently altered hNSC migration and reversed astroglial fate after spinal cord injury. Collectively, these data suggest that modulation of the innate/humoral inflammatory microenvironment may impact the potential of cell-based therapies for recovery and repair following CNS pathology.


Assuntos
Astrócitos/fisiologia , Diferenciação Celular/fisiologia , Complemento C1q/biossíntese , Complemento C3a/biossíntese , Células-Tronco Neurais/fisiologia , Neutrófilos/metabolismo , Animais , Astrócitos/efeitos dos fármacos , Movimento Celular , Células Cultivadas , Complemento C1q/antagonistas & inibidores , Complemento C1q/genética , Complemento C1q/imunologia , Complemento C3a/antagonistas & inibidores , Complemento C3a/genética , Complemento C3a/imunologia , Meios de Cultivo Condicionados , Humanos , Imunidade Inata , Camundongos , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/imunologia , Neutrófilos/imunologia , Traumatismos da Medula Espinal/imunologia , Traumatismos da Medula Espinal/fisiopatologia
13.
Nucleic Acids Res ; 45(5): 2503-2515, 2017 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-28158710

RESUMO

T: Activator protein 1 (AP-1) is a transcription factor that recognizes two versions of a 7-base pair response element, either 5΄- GAG CA-3΄ or 5΄- GAG CA-3΄ (where M = 5-methylcytosine). These two elements share the feature that 5-methylcytosine and thymine both have a methyl group in the same position, 5-carbon of the pyrimidine, so each of them has two methyl groups at nucleotide positions 1 and 5 from the 5΄ end, resulting in four methyl groups symmetrically positioned in duplex DNA. Epstein-Barr Virus Zta is a key transcriptional regulator of the viral lytic cycle that is homologous to AP-1. Zta recognizes several methylated Zta-response elements, including meZRE1 (5΄- GAG C A-3΄) and meZRE2 (5΄- GAG G A-3΄), where a methylated cytosine occupies one of the inner thymine residues corresponding to the AP-1 element, resulting in the four spatially equivalent methyl groups. Here, we study how AP-1 and Zta recognize these methyl groups within their cognate response elements. These methyl groups are in van der Waals contact with a conserved di-alanine in AP-1 dimer (Ala265 and Ala266 in Jun), or with the corresponding Zta residues Ala185 and Ser186 (via its side chain carbon Cß atom). Furthermore, the two ZRE elements differ at base pair 6 (C:G versus G:C), forming a pseudo-symmetric sequence (meZRE1) or an asymmetric sequence (meZRE2). In vitro DNA binding assays suggest that Zta has high affinity for all four sequences examined, whereas AP-1 has considerably reduced affinity for the asymmetric sequence (meZRE2). We ascribe this difference to Zta Ser186 (a unique residue for Zta) whose side chain hydroxyl oxygen atom interacts with the two half sites differently, whereas the corresponding Ala266 of AP-1 Jun protein lacks such flexibility. Our analyses demonstrate a novel mechanism of 5mC/T recognition in a methylation-dependent, spatial and sequence-specific approach by basic leucine-zipper transcriptional factors.


Assuntos
Metilação de DNA , Proteínas Proto-Oncogênicas c-jun/química , Elementos de Resposta , Transativadores/química , 5-Metilcitosina/química , Pareamento de Bases , Sítios de Ligação , DNA/química , DNA/metabolismo , Humanos , Ligação Proteica , Multimerização Proteica , Proteínas Proto-Oncogênicas c-jun/metabolismo , Timina/química , Transativadores/metabolismo , Fator de Transcrição AP-1/química , Fator de Transcrição AP-1/metabolismo
14.
Clin Infect Dis ; 66(6): 877-885, 2018 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-29069323

RESUMO

Background: Salmonella 4,[5],12:i:-, a worldwide emerging pathogen that causes many food-borne outbreaks mostly attributed to pig and pig products, is expanding in the United States. Methods: Whole-genome sequencing was applied to conduct multiple comparisons of 659 S. 4,[5],12:i:- and 325 Salmonella Typhimurium from different sources and locations (ie, the United States and Europe) to assess their genetic heterogeneity, with a focus on strains recovered from swine in the US Midwest. In addition, the presence of resistance genes and other virulence factors was detected and the antimicrobial resistance phenotypes of 50 and 22 isolates of livestock and human origin, respectively, was determined. Results: The S. 4,5,12:i:- strains formed two main clades regardless of their source and geographic origin. Most (84%) of the US isolates recovered in 2014-2016, including those (48 of 51) recovered from swine in the US Midwest, were part of an emerging clade. In this clade, multiple genotypic resistance determinants were predominant, including resistance against ampicillin, streptomycin, sulfonamides, and tetracyclines. Phenotypic resistance to enrofloxacin (11 of 50) and ceftiofur (9 of 50) was found in conjunction with the presence of plasmid-mediated resistance genes (qnrB19/qnrB2/qnrS1 and blaCMY-2/blaSHV-12, respectively). Higher similarity was also found between S. 4,[5],12:i:- from the emerging clade and S. Typhimurium from Europe than with S. Typhimurium from the United States. Conclusions: Salmonella 4,[5],12:i:- currently circulating in swine in the US Midwest are likely to be part of an emerging multidrug-resistant clade first reported in Europe, and can carry plasmid-mediated resistance genes that may be transmitted horizontally to other bacteria, and thus may represent a public health concern.


Assuntos
Farmacorresistência Bacteriana Múltipla/genética , Salmonelose Animal/epidemiologia , Salmonella enterica/genética , Sorogrupo , Animais , Antibacterianos/farmacologia , Europa (Continente)/epidemiologia , Variação Genética , Genótipo , Testes de Sensibilidade Microbiana , Meio-Oeste dos Estados Unidos/epidemiologia , Fenótipo , Quinolonas/farmacologia , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/isolamento & purificação , Salmonella typhimurium/genética , Salmonella typhimurium/isolamento & purificação , Suínos/microbiologia , Fatores de Virulência/genética , Sequenciamento Completo do Genoma
15.
Adv Exp Med Biol ; 945: 321-341, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27826845

RESUMO

The modification of DNA bases is a classic hallmark of epigenetics. Four forms of modified cytosine-5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine-have been discovered in eukaryotic DNA. In addition to cytosine carbon-5 modifications, cytosine and adenine methylated in the exocyclic amine-N4-methylcytosine and N6-methyladenine-are other modified DNA bases discovered even earlier. Each modified base can be considered a distinct epigenetic signal with broader biological implications beyond simple chemical changes. Since 1994, crystal structures of proteins and enzymes involved in writing, reading, and erasing modified bases have become available. Here, we present a structural synopsis of writers, readers, and erasers of the modified bases from prokaryotes and eukaryotes. Despite significant differences in structures and functions, they are remarkably similar regarding their engagement in flipping a target base/nucleotide within DNA for specific recognitions and/or reactions. We thus highlight base flipping as a common structural framework broadly applied by distinct classes of proteins and enzymes across phyla for epigenetic regulations of DNA.


Assuntos
Metilação de DNA/genética , Proteínas de Ligação a DNA/genética , DNA/química , Epigênese Genética , 5-Metilcitosina/análogos & derivados , 5-Metilcitosina/química , 5-Metilcitosina/metabolismo , Adenina/química , Adenina/metabolismo , Citosina/análogos & derivados , Citosina/química , Citosina/metabolismo , DNA/genética , DNA/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/classificação , Eucariotos/metabolismo , Células Procarióticas/metabolismo , Domínios Proteicos/genética
16.
Nucleic Acids Res ; 40(20): 10203-14, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22962365

RESUMO

The mammalian thymine DNA glycosylase (TDG) is implicated in active DNA demethylation via the base excision repair pathway. TDG excises the mismatched base from G:X mismatches, where X is uracil, thymine or 5-hydroxymethyluracil (5hmU). These are, respectively, the deamination products of cytosine, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). In addition, TDG excises the Tet protein products 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) but not 5hmC and 5mC, when paired with a guanine. Here we present a post-reactive complex structure of the human TDG domain with a 28-base pair DNA containing a G:5hmU mismatch. TDG flips the target nucleotide from the double-stranded DNA, cleaves the N-glycosidic bond and leaves the C1' hydrolyzed abasic sugar in the flipped state. The cleaved 5hmU base remains in a binding pocket of the enzyme. TDG allows hydrogen-bonding interactions to both T/U-based (5hmU) and C-based (5caC) modifications, thus enabling its activity on a wider range of substrates. We further show that the TDG catalytic domain has higher activity for 5caC at a lower pH (5.5) as compared to the activities at higher pH (7.5 and 8.0) and that the structurally related Escherichia coli mismatch uracil glycosylase can excise 5caC as well. We discuss several possible mechanisms, including the amino-imino tautomerization of the substrate base that may explain how TDG discriminates against 5hmC and 5mC.


Assuntos
Citosina/análogos & derivados , DNA/química , Pentoxil (Uracila)/análogos & derivados , Timina DNA Glicosilase/química , Biocatálise , Domínio Catalítico , Citosina/química , Citosina/metabolismo , DNA/metabolismo , Humanos , Modelos Moleculares , Pentoxil (Uracila)/química , Pentoxil (Uracila)/metabolismo , Timina DNA Glicosilase/metabolismo
17.
Am J Clin Dermatol ; 25(4): 513-525, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38635019

RESUMO

BACKGROUND: Ultrasound surveillance has become the new standard of care in stage III melanoma after the 2017 Multicenter Selective Lymphadenectomy Trial II (MSLT-II) demonstrated non-inferior 3-year survival compared with complete lymph node dissection. OBJECTIVE: We aimed to quantify diagnostic performance and adherence rates of ultrasound surveillance for melanoma locoregional metastasis, offering insights into real-world applicability. METHODS: Conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we systematically searched the Medline, Embase, Cochrane Library, CINAHL, Scopus, and Web of Science databases from inception until 11 October 2023. All primary studies that reported data on the diagnostic performance or adherence rates to ultrasound surveillance in melanoma were included. R statistical software was used for data synthesis and analysis. Sensitivity and specificity were aggregated across studies using the meta-analytic method for diagnostic tests outlined by Rutter and Gatsonis. Adherence rates were calculated as the ratio of patients fully compliant to planned follow-up to those who were not. RESULTS: A total of 36 studies including 18,273 patients were analysed, with a mean age of 56.6 years and a male-to-female ratio of 1:1.11. The median follow-up duration and frequency was 36 and 4 months, respectively. The pooled sensitivity of ultrasound examination was 0.879 (95% confidence interval [CI] 0.878-0.879) and specificity was 0.969 (95% CI 0.968-0.970), representing a diagnostic odds ratio of 224.5 (95% CI 223.1-225.9). Ultrasound examination demonstrated a substantial improvement in absolute sensitivity over clinical examination alone, with a number needed to screen (NNS) of 2.95. The overall adherence rate was 77.0% (95% CI 76.0-78.1%), with significantly lower rates in the United States [US] (p <  0.001) and retrospective studies (p <  0.001). CONCLUSION: Ultrasound is a powerful diagnostic tool for locoregional melanoma metastasis. However, the real applicability to surveillance programmes is limited by low adherence rates, especially in the US. Further studies should seek to address this adherence gap.


Assuntos
Melanoma , Neoplasias Cutâneas , Ultrassonografia , Humanos , Melanoma/diagnóstico por imagem , Melanoma/patologia , Melanoma/diagnóstico , Neoplasias Cutâneas/diagnóstico por imagem , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/diagnóstico , Ultrassonografia/métodos , Ultrassonografia/estatística & dados numéricos , Sensibilidade e Especificidade , Metástase Linfática/diagnóstico por imagem , Estadiamento de Neoplasias , Cooperação do Paciente/estatística & dados numéricos , Excisão de Linfonodo/métodos
18.
medRxiv ; 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38883783

RESUMO

Phylogeographic analyses are able to exploit the location data associated with sampled molecular sequences to reconstruct the spatio-temporal dispersal history of a pathogen. Visualisation software is commonly used to facilitate the interpretation of the accompanying estimation results, as these are not always easily interpretable. spread.gl is a powerful, open-source and feature-rich browser application that enables smooth, intuitive and user-friendly visualisation of both discrete and continuous phylogeographic inference results, enabling the animation of pathogen geographic dispersal through time. spread.gl can render and combine the visualisation of several data layers, including a geographic layer (e.g., a world map), multiple layers that contain information extracted from the input phylogeny, and different types of layers that represent environmental data. As such, users can explore which environmental data may have shaped pathogen dispersal patterns, that can subsequently be formally tested through more principled statistical analyses. We showcase the visualisation features of spread.gl on several representative pathogen dispersal examples, including the smooth animation of a phylogeny encompassing over 17,000 genomic sequences resulting from a large-scale SARS-CoV-2 analysis.

19.
Res Sq ; 2024 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-38260385

RESUMO

B-cell maturation antigen (BCMA) plays a pathobiologic role in myeloma and is a validated target with five BCMA-specific therapeutics having been approved for relapsed/refractory disease. However, these drugs are not curative, and responses are inferior in patients with molecularly-defined high-risk disease, including those with deletion 17p (del17p) involving the tumor suppressor TP53, supporting the need for further drug development. Del17p has been associated with reduced copy number and gene expression of RNA polymerase II subunit alpha (POLR2A) in other tumor types. We therefore studied the possibility that HDP-101, an anti-BCMA antibody drug conjugate (ADC) with the POLR2A poison α-amanitin could be an attractive agent in myeloma, especially with del17p. HDP-101 reduced viability in myeloma cell lines representing different molecular disease subtypes, and overcame adhesion-mediated and both conventional and novel drug resistance. After confirming that del17p is associated with reduced POLR2A levels in publicly available myeloma patient databases, we engineered TP53 wild-type cells with a TP53 knockout (KO), POLR2A knockdown (KD), or both, the latter to mimic del17p. HDP-101 showed potent anti-myeloma activity against all tested cell lines, and exerted enhanced efficacy against POLR2A KD and dual TP53 KO/POLR2A KD cells. Mechanistic studies showed HDP-101 up-regulated the unfolded protein response, activated apoptosis, and induced immunogenic cell death. Notably, HDP-101 impacted CD138-positive but not-negative primary cells, showed potent efficacy against aldehyde dehydrogenase-positive clonogenic cells, and eradicated myeloma in an in vivo cell line-derived xenograft (CDX). Interestingly, in the CDX model, prior treatment with HDP-101 precluded subsequent engraftment on tumor cell line rechallenge in a manner that appeared to be dependent in part on natural killer cells and macrophages. Finally, HDP-101 was superior to the BCMA-targeted ADC belantamab mafodotin against cell lines and primary myeloma cells in vitro, and in an in vivo CDX. Together, the data support the rationale for translation of HDP-101 to the clinic, where it is now undergoing Phase I trials, and suggest that it could emerge as a more potent ADC for myeloma with especially interesting activity against the high-risk del17p myeloma subtype.

20.
medRxiv ; 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38463998

RESUMO

The dynamics of SARS-CoV-2 transmission are influenced by a variety of factors, including social restrictions and the emergence of distinct variants. In this study, we delve into the origins and dissemination of the Alpha, Delta, and Omicron variants of concern in Galicia, northwest Spain. For this, we leveraged genomic data collected by the EPICOVIGAL Consortium and from the GISAID database, along with mobility information from other Spanish regions and foreign countries. Our analysis indicates that initial introductions during the Alpha phase were predominantly from other Spanish regions and France. However, as the pandemic progressed, introductions from Portugal and the USA became increasingly significant. Notably, Galicia's major coastal cities emerged as critical hubs for viral transmission, highlighting their role in sustaining and spreading the virus. This research emphasizes the critical role of regional connectivity in the spread of SARS-CoV-2 and offers essential insights for enhancing public health strategies and surveillance measures.

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