Recent work suggests extensive adaptation of transposable elements (TEs) for host gene regulation. However, high numbers of integrations typical of TEs, coupled with sequence divergence within ...families, have made systematic interrogation of the regulatory contributions of TEs challenging. Here, we employ CARGO, our recent method for CRISPR gRNA multiplexing, to facilitate targeting of LTR5HS, an ape-specific class of HERVK (HML-2) LTRs that is active during early development and present in ~700 copies throughout the human genome. We combine CARGO with CRISPR activation or interference to, respectively, induce or silence LTR5HS en masse, and demonstrate that this system robustly targets the vast majority of LTR5HS insertions. Remarkably, activation/silencing of LTR5HS is associated with reciprocal up- and down-regulation of hundreds of human genes. These effects require the presence of retroviral sequences, but occur over long genomic distances, consistent with a pervasive function of LTR5HS elements as early embryonic enhancers in apes.
Direct lineage reprogramming is a promising approach for human disease modeling and regenerative medicine, with poorly understood mechanisms. Here, we reveal a hierarchical mechanism in the direct ...conversion of fibroblasts into induced neuronal (iN) cells mediated by the transcription factors Ascl1, Brn2, and Myt1l. Ascl1 acts as an “on-target” pioneer factor by immediately occupying most cognate genomic sites in fibroblasts. In contrast, Brn2 and Myt1l do not access fibroblast chromatin productively on their own; instead, Ascl1 recruits Brn2 to Ascl1 sites genome wide. A unique trivalent chromatin signature in the host cells predicts the permissiveness for Ascl1 pioneering activity among different cell types. Finally, we identified Zfp238 as a key Ascl1 target gene that can partially substitute for Ascl1 during iN cell reprogramming. Thus, a precise match between pioneer factors and the chromatin context at key target genes is determinative for transdifferentiation to neurons and likely other cell types.
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•Ascl1 has pioneer activity, accessing closed chromatin to allow other factors to bind•Unlike other pioneer factors, Ascl1 binds its physiologic neural targets in fibroblasts•A trivalent chromatin domain predicts iN reprogramming ability in other cell types•Zfp238 is a direct Ascl1 target and critical mediator of iN cell reprogramming
Of three transcription factors that together convert different cell types into induced neuronal (iN) cells, Ascl1 leads the way as the “pioneer factor,” followed by Brn2 and Myt1l. A trivalent chromatin state at Ascl1 target genes predicts which types of cells will respond to reprogramming by these factors.
Somatic cell nuclear transfer, cell fusion, or expression of lineage-specific factors have been shown to induce cell-fate changes in diverse somatic cell types. We recently observed that forced ...expression of a combination of three transcription factors, Brn2 (also known as Pou3f2), Ascl1 and Myt1l, can efficiently convert mouse fibroblasts into functional induced neuronal (iN) cells. Here we show that the same three factors can generate functional neurons from human pluripotent stem cells as early as 6 days after transgene activation. When combined with the basic helix-loop-helix transcription factor NeuroD1, these factors could also convert fetal and postnatal human fibroblasts into iN cells showing typical neuronal morphologies and expressing multiple neuronal markers, even after downregulation of the exogenous transcription factors. Importantly, the vast majority of human iN cells were able to generate action potentials and many matured to receive synaptic contacts when co-cultured with primary mouse cortical neurons. Our data demonstrate that non-neural human somatic cells, as well as pluripotent stem cells, can be converted directly into neurons by lineage-determining transcription factors. These methods may facilitate robust generation of patient-specific human neurons for in vitro disease modelling or future applications in regenerative medicine.
CHARGE syndrome is a multiple anomaly disorder in which patients present with a variety of phenotypes, including ocular coloboma, heart defects, choanal atresia, retarded growth and development, ...genitourinary hypoplasia and ear abnormalities. Despite 70-90% of CHARGE syndrome cases resulting from mutations in the gene CHD7, which encodes an ATP-dependent chromatin remodeller, the pathways underlying the diverse phenotypes remain poorly understood. Surprisingly, our studies of a knock-in mutant mouse strain that expresses a stabilized and transcriptionally dead variant of the tumour-suppressor protein p53 (p53(25,26,53,54)), along with a wild-type allele of p53 (also known as Trp53), revealed late-gestational embryonic lethality associated with a host of phenotypes that are characteristic of CHARGE syndrome, including coloboma, inner and outer ear malformations, heart outflow tract defects and craniofacial defects. We found that the p53(25,26,53,54) mutant protein stabilized and hyperactivated wild-type p53, which then inappropriately induced its target genes and triggered cell-cycle arrest or apoptosis during development. Importantly, these phenotypes were only observed with a wild-type p53 allele, as p53(25,26,53,54)(/-) embryos were fully viable. Furthermore, we found that CHD7 can bind to the p53 promoter, thereby negatively regulating p53 expression, and that CHD7 loss in mouse neural crest cells or samples from patients with CHARGE syndrome results in p53 activation. Strikingly, we found that p53 heterozygosity partially rescued the phenotypes in Chd7-null mouse embryos, demonstrating that p53 contributes to the phenotypes that result from CHD7 loss. Thus, inappropriate p53 activation during development can promote CHARGE phenotypes, supporting the idea that p53 has a critical role in developmental syndromes and providing important insight into the mechanisms underlying CHARGE syndrome.
The aim of this study was to analyze the effect of performing different type of passing triangulations in the own half on the ball possession and progression in professional football. A total of ...70,653 triangulations in the own half that took place during 380 matches from the Spanish La Liga 2018/2019 were analyzed by using event data provided by StatsPerform. All triangulations were classified into two groups: (i) one with triangulations involving a side lane repetition and (ii) a second group with those triangulations without a side lane repetition. Considering this classification, we conducted two complementary analyses: one differentiating these two types of triangulations and another considering what kind of plays contained lateral lane repetitions, paying special attention to plays that ended in the loss of the ball. In both analyses, results show the same conclusion: a triangulation in which side lane is repeated or a play in which at least one side lane repetition is included have a greater tendency to finish with a turnover than other types of triangulations or plays in which this type of side lane repetition does not appear.
Normal differentiation and induced reprogramming require the activation of target cell programs and silencing of donor cell programs. In reprogramming, the same factors are often used to reprogram ...many different donor cell types. As most developmental repressors, such as RE1-silencing transcription factor (REST) and Groucho (also known as TLE), are considered lineage-specific repressors, it remains unclear how identical combinations of transcription factors can silence so many different donor programs. Distinct lineage repressors would have to be induced in different donor cell types. Here, by studying the reprogramming of mouse fibroblasts to neurons, we found that the pan neuron-specific transcription factor Myt1-like (Myt1l) exerts its pro-neuronal function by direct repression of many different somatic lineage programs except the neuronal program. The repressive function of Myt1l is mediated via recruitment of a complex containing Sin3b by binding to a previously uncharacterized N-terminal domain. In agreement with its repressive function, the genomic binding sites of Myt1l are similar in neurons and fibroblasts and are preferentially in an open chromatin configuration. The Notch signalling pathway is repressed by Myt1l through silencing of several members, including Hes1. Acute knockdown of Myt1l in the developing mouse brain mimicked a Notch gain-of-function phenotype, suggesting that Myt1l allows newborn neurons to escape Notch activation during normal development. Depletion of Myt1l in primary postmitotic neurons de-repressed non-neuronal programs and impaired neuronal gene expression and function, indicating that many somatic lineage programs are actively and persistently repressed by Myt1l to maintain neuronal identity. It is now tempting to speculate that similar 'many-but-one' lineage repressors exist for other cell fates; such repressors, in combination with lineage-specific activators, would be prime candidates for use in reprogramming additional cell types.
ACTIVIDAD ANTIOXIDANTE, HIPOLIPEMIANTE Y ANTIPLAQUETARIA DEL TOMATE (Solanum lycopersicum L.) Y EL EFECTO DE SU PROCESAMIENTO Y ALMACENAJE Palomo G, Iván(Universidad de Talca Facultad de Ciencias de la Salud Departamento de Bioquímica Clínica e Inmunohematología); Fuentes Q, Eduardo(Universidad de Talca Facultad de Ciencias de la Salud Departamento de Bioquímica Clínica e Inmunohematología); Carrasco S, Gilda(Universidad de Talca Facultad de Ciencias Agrarias Departamento de Horticultura) ...
Revista chilena de nutrición,
2010, Volume:
37, Issue:
4
Journal Article
Open access
Cardiovascular diseases (CVD) are the main cause of mortality worldwide. To prevent CVD it is recommended to quit smoking, the practice of physical activity and the consumption of healthy food. In ...this context, numerous studies have shown the importance of frequent consumption of fruits and vegetables (at least5 a day). It has been described an inverse relationship between vegetables consumption and the risk of developing CVD, which is mainly explained by its antioxidant activity, and in some cases lipid-lowering and platelet effects. In this sense, the increase in regular consumption of tomato (Solanum lycopersicum L.) and related products, can improve the some cardiovascular parameters. The current lifestyle favors the consumption of processed foods, a situation that may affect the stability of tomato components and their physicochemical properties. This review addresses the antioxidant activities, lipid-lowering and antiaggregant properties of tomato, as well as the effect of processing and storage. Additionally, a summary of some patents associated with beneficial effects on health. As bibliographic source www.pubmed.org was mainly used, the terms used in the search were and platelet, tomato, and platelet, antioxidant, among others, then search the full texts of items of common interest.
Las enfermedades cardiovasculares (ECV) son la principal causa de muerte en el mundo. En su prevención tiene mucha importancia el no fumar, realizar actividad física y consumir alimentos saludables. En este contexto, numerosos estudios han demostrado la importancia del consumo frecuente de frutas y hortalizas (al menos 5 porciones al día). Se ha descrito una relación inversa entre su ingesta y el riesgo de desarrollar ECV, lo que se explica principalmente por su actividad antioxidante, hipolipemiante y en algunos casos antiplaquetaria. En ese sentido aumentar el consumo actual de tomate (Solanum lycopersicum L.) y productos del tomate, puede mejorar algunos parámetros cardiovasculares. El actual estilo de vida induce a las personas a consumir alimentos procesados, lo que podría afectar la estabilidad de sus componentes y sus propiedades fisicoquímicas. Esta revisión aborda la actividad antioxidante, hipolipemiante y antiagregante plaquetaria del tomate, como también el efecto que tiene el procesamiento y almacenaje sobre dichas actividades. Adicionalmente se resumen algunas patentes asociadas a efectos beneficiosos en la salud. Como fuentes bibliográficas se utilizó principalmente www.pubmed.org; los términos utilizados en la búsqueda fueron: antiplatelet, tomato, platelet, antioxidant, entre otros; luego se buscaron los textos completos de los artículos que interesaban.
El endotelio normal ayuda a mantener la estructura y la hemostasia vascular. Sin embargo, la exposición crónica a factores de riesgo cardiovascular (CV) produce disfunción endotelial, fenómeno que se ...caracteriza por inflamación, disminución en la biodisponibilidad de óxido nítrico (NO) y un estado protrombótico. Estudios epidemiológicos han demostrado que el consumo regular de frutas y hortalizas disminuye el riesgo CV, lo que ha causado interés en conocer los compuestos bioactivos y los mecanismos involucrados. Entre los componentes que protegen el endotelio se encuentran las moléculas antioxidantes (vitamina C, vitamina E y polifenoles) y ácidos grasos poliinsaturados. Las vitaminas C y E favorecen la vasodilatación protegiendo el NO al bloquear las especies reactivas del oxigeno (ROS). Los polifenoles mejoran la función endotelial principalmente por el aumento de los niveles de NO, y la inhibición de la angiogénesis y de la activación plaquetaria. Dietas ricas en ácidos grasos poliinsaturados han mostrado efectos beneficiosos, mediante la reducción de la expresión géni-ca de la ciclooxigenasa-2 y de la expresión de moléculas de adhesión celular. Esta revisión principalmente señala los conocimientos actuales de la disfunción endotelial y el efecto protector de las células endoteliales por componentes bioactivos de frutas y hortalizas.
Direct lineage reprogramming is a promising approach for human disease modeling and regenerative medicine with poorly understood mechanisms. Here we reveal a hierarchical mechanism in the direct ...conversion of fibroblasts into induced neuronal (iN) cells mediated by the transcription factors Ascl1, Brn2, and Myt1l. Ascl1 acts as an “on target” pioneer factor by immediately occupying most cognate genomic sites in fibroblasts. In contrast, Brn2 and Myt1l do not access fibroblast chromatin productively on their own; instead Ascl1 recruits Brn2 to Ascl1 sites genome-wide. A unique trivalent chromatin signature in the host cells predicts the permissiveness for Ascl1 pioneering activity among different cell types. Finally, we identified Zfp238 as a key Ascl1 target gene that can partially substitute for Ascl1 during iN cell reprogramming. Thus, precise match between pioneer factor and the chromatin context at key target genes is determinative for trans-differentiation to neurons and likely other cell types.
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