RESUMEN
To mechanistically characterize the microevolutionary processes active in altering transcription factor (TF) binding among closely related mammals, we compared the genome-wide binding of three tissue-specific TFs that control liver gene expression in six rodents. Despite an overall fast turnover of TF binding locations between species, we identified thousands of TF regions of highly constrained TF binding intensity. Although individual mutations in bound sequence motifs can influence TF binding, most binding differences occur in the absence of nearby sequence variations. Instead, combinatorial binding was found to be significant for genetic and evolutionary stability; cobound TFs tend to disappear in concert and were sensitive to genetic knockout of partner TFs. The large, qualitative differences in genomic regions bound between closely related mammals, when contrasted with the smaller, quantitative TF binding differences among Drosophila species, illustrate how genome structure and population genetics together shape regulatory evolution.
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Evolución Molecular , Ratones/clasificación , Ratones/genética , Factores de Transcripción/genética , Animales , Drosophila/genética , Hígado/metabolismo , Ratones/metabolismo , Ratones Endogámicos , Ratones Noqueados , Ratas/genética , Factores de Transcripción/metabolismoRESUMEN
A comprehensive catalog of cancer driver mutations is essential for understanding tumorigenesis and developing therapies. Exome-sequencing studies have mapped many protein-coding drivers, yet few non-coding drivers are known because genome-wide discovery is challenging. We developed a driver discovery method, ActiveDriverWGS, and analyzed 120,788 cis-regulatory modules (CRMs) across 1,844 whole tumor genomes from the ICGC-TCGA PCAWG project. We found 30 CRMs with enriched SNVs and indels (FDR < 0.05). These frequently mutated regulatory elements (FMREs) were ubiquitously active in human tissues, showed long-range chromatin interactions and mRNA abundance associations with target genes, and were enriched in motif-rewiring mutations and structural variants. Genomic deletion of one FMRE in human cells caused proliferative deficiencies and transcriptional deregulation of cancer genes CCNB1IP1, CDH1, and CDKN2B, validating observations in FMRE-mutated tumors. Pathway analysis revealed further sub-significant FMREs at cancer genes and processes, indicating an unexplored landscape of infrequent driver mutations in the non-coding genome.
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Biomarcadores de Tumor/genética , Cromatina/metabolismo , Redes Reguladoras de Genes , Mutación , Neoplasias/genética , Neoplasias/patología , Secuencias Reguladoras de Ácidos Nucleicos , Proliferación Celular , Cromatina/genética , Biología Computacional/métodos , Análisis Mutacional de ADN , Genoma Humano , Células HEK293 , HumanosRESUMEN
CTCF-binding locations represent regulatory sequences that are highly constrained over the course of evolution. To gain insight into how these DNA elements are conserved and spread through the genome, we defined the full spectrum of CTCF-binding sites, including a 33/34-mer motif, and identified over five thousand highly conserved, robust, and tissue-independent CTCF-binding locations by comparing ChIP-seq data from six mammals. Our data indicate that activation of retroelements has produced species-specific expansions of CTCF binding in rodents, dogs, and opossum, which often functionally serve as chromatin and transcriptional insulators. We discovered fossilized repeat elements flanking deeply conserved CTCF-binding regions, indicating that similar retrotransposon expansions occurred hundreds of millions of years ago. Repeat-driven dispersal of CTCF binding is a fundamental, ancient, and still highly active mechanism of genome evolution in mammalian lineages.
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Evolución Molecular , Proteínas Represoras/metabolismo , Retroelementos , Secuencia de Aminoácidos , Animales , Factor de Unión a CCCTC , Inmunoprecipitación de Cromatina , Genoma , Genoma Humano , Humanos , Datos de Secuencia Molecular , Unión Proteica , Alineación de Secuencia , Factores de Transcripción/metabolismoRESUMEN
In this issue of Molecular Cell, Gothe, Maman et al. and Canela et al. demonstrate that type II topoisomerase (TOP2B/TOP2A)-mediated DNA breaks, and the oncogenic translocations they generate, are dependent on transcription and governed by chromatin architecture.
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ADN-Topoisomerasas de Tipo II/genética , Proteínas de Unión al ADN/genética , Cromatina , Cromosomas , ADN , Daño del ADNRESUMEN
Targeting bromodomains (BRDs) of the bromo-and-extra-terminal (BET) family offers opportunities for therapeutic intervention in cancer and other diseases. Here, we profile the interactomes of BRD2, BRD3, BRD4, and BRDT following treatment with the pan-BET BRD inhibitor JQ1, revealing broad rewiring of the interaction landscape, with three distinct classes of behavior for the 603 unique interactors identified. A group of proteins associate in a JQ1-sensitive manner with BET BRDs through canonical and new binding modes, while two classes of extra-terminal (ET)-domain binding motifs mediate acetylation-independent interactions. Last, we identify an unexpected increase in several interactions following JQ1 treatment that define negative functions for BRD3 in the regulation of rRNA synthesis and potentially RNAPII-dependent gene expression that result in decreased cell proliferation. Together, our data highlight the contributions of BET protein modules to their interactomes allowing for a better understanding of pharmacological rewiring in response to JQ1.
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Antineoplásicos/farmacología , Azepinas/farmacología , Terapia Molecular Dirigida/métodos , Neoplasias/tratamiento farmacológico , Proteínas Nucleares/antagonistas & inhibidores , Mapas de Interacción de Proteínas/efectos de los fármacos , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas de Unión al ARN/antagonistas & inhibidores , Factores de Transcripción/antagonistas & inhibidores , Triazoles/farmacología , Antineoplásicos/química , Azepinas/química , Proteínas de Ciclo Celular , Proliferación Celular/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica , Células HEK293 , Células HeLa , Humanos , Células K562 , Modelos Moleculares , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Unión Proteica , Conformación Proteica , Dominios y Motivos de Interacción de Proteínas , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Proteómica/métodos , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Transducción de Señal/efectos de los fármacos , Relación Estructura-Actividad , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Triazoles/químicaRESUMEN
Genome sequencing (GS) is a powerful test for the diagnosis of rare genetic disorders. Although GS can enumerate most non-coding variation, determining which non-coding variants are disease-causing is challenging. RNA sequencing (RNA-seq) has emerged as an important tool to help address this issue, but its diagnostic utility remains understudied, and the added value of a trio design is unknown. We performed GS plus RNA-seq from blood using an automated clinical-grade high-throughput platform on 97 individuals from 39 families where the proband was a child with unexplained medical complexity. RNA-seq was an effective adjunct test when paired with GS. It enabled clarification of putative splice variants in three families, but it did not reveal variants not already identified by GS analysis. Trio RNA-seq decreased the number of candidates requiring manual review when filtering for de novo dominant disease-causing variants, allowing for the exclusion of 16% of gene-expression outliers and 27% of allele-specific-expression outliers. However, clear diagnostic benefit from the trio design was not observed. Blood-based RNA-seq can facilitate genome analysis in children with suspected undiagnosed genetic disease. In contrast to DNA sequencing, the clinical advantages of a trio RNA-seq design may be more limited.
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Familia , Enfermedades Raras , Humanos , Niño , Secuencia de Bases , Análisis de Secuencia de ADN , Secuenciación del Exoma , Enfermedades Raras/genética , Análisis de Secuencia de ARNRESUMEN
The question of how the heart develops, and the genetic networks governing this process have become intense areas of research over the past several decades. This research is propelled by classical developmental studies and potential clinical applications to understand and treat congenital conditions in which cardiac development is disrupted. Discovery of the tinman gene in Drosophila, and examination of its vertebrate homolog Nkx2.5, along with other core cardiac transcription factors has revealed how cardiac progenitor differentiation and maturation drives heart development. Careful observation of cardiac morphogenesis along with lineage tracing approaches indicated that cardiac progenitors can be divided into two broad classes of cells, namely the first and second heart fields, that contribute to the heart in two distinct waves of differentiation. Ample evidence suggests that the fate of individual cardiac progenitors is restricted to distinct cardiac structures quite early in development, well before the expression of canonical cardiac progenitor markers like Nkx2.5. Here we review the initial specification of cardiac progenitors, discuss evidence for the early patterning of cardiac progenitors during gastrulation, and consider how early gene expression programs and epigenetic patterns can direct their development. A complete understanding of when and how the developmental potential of cardiac progenitors is determined, and their potential plasticity, is of great interest developmentally and also has important implications for both the study of congenital heart disease and therapeutic approaches based on cardiac stem cell programming.
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Gastrulación , Mesodermo , Animales , Drosophila/genética , Regulación del Desarrollo de la Expresión Génica , CorazónRESUMEN
Plasmodium falciparum malaria remains a disease of significant public health impact today. With the risk of emerging artemisinin resistance stalling malaria control efforts, the need to deepen our understanding of the parasite's biology is dire. Extracellular vesicles (EVs) are vital to the biology of P. falciparum and play a role in the pathogenesis of malaria. Recent studies have also shown that EVs may play a role in the development of artemisinin resistance in P. falciparum. Here, we highlight evidence on EVs in P. falciparum biology and malaria pathogenesis and argue that there is sufficient ground to propose a role for EVs in the development of P. falciparum artemisinin resistance. We suggest that EVs are actively secreted functional organelles that contribute to cellular homeostasis in P. falciparum-infected red blood cells under artemisinin pressure. Further exploration of this hypothesized EVs-based molecular mechanism of artemisinin resistance will aid the discovery of novel antimalarial therapies.
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Antimaláricos , Artemisininas , Vesículas Extracelulares , Malaria Falciparum , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Artemisininas/farmacología , Artemisininas/uso terapéutico , Humanos , Malaria Falciparum/tratamiento farmacológico , Plasmodium falciparumRESUMEN
Transcription of the cystic fibrosis transmembrane conductance regulator (CFTR) gene is regulated by both ubiquitous and cell-type selective cis-regulatory elements (CREs). These CREs include extragenic and intronic enhancers that bind lineage-specific transcription factors, and architectural protein-marked structural elements. Deletion of the airway-selective -35 kb enhancer in 16HBE14o- lung epithelial cells was shown earlier to disrupt normal enhancer-promoter looping at the CFTR locus and nearly abolish its expression. Using a 16HBE14o- clone that lacks the endogenous -35 kb CRE, we explore the impact of relocating the functional core of this element to an ectopic site in intron 1. The -35 kb sequence establishes a de novo enhancer signature in chromatin at the insertion site, and augments CFTR expression, albeit not fully restoring WT levels. The relocated -35 kb enhancer also initiates de novo chromatin contacts with the CFTR promoter and other known CFTR CREs. These results are broadly relevant to therapeutic gene editing.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística , Elementos de Facilitación Genéticos , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Factores de Transcripción/genética , Regiones Promotoras Genéticas , Cromatina/genéticaRESUMEN
During gestation, uterine smooth muscle cells transition from a state of quiescence to one of contractility, but the molecular mechanisms underlying this transition at a genomic level are not well-known. To better understand these events, we evaluated the epigenetic landscape of the mouse myometrium during the pregnant, laboring, and postpartum stages. We generated gestational time point-specific enrichment profiles for histone H3 acetylation on lysine residue 27 (H3K27ac), histone H3 trimethylation of lysine residue 4 (H3K4me3), and RNA polymerase II (RNAPII) occupancy by chromatin immunoprecipitation with massively parallel sequencing (ChIP-seq), as well as gene expression profiles by total RNA-sequencing (RNA-seq). Our findings reveal that 533 genes, including known contractility-driving genes (Gap junction alpha 1 [Gja1], FBJ osteosarcoma oncogene [Fos], Fos-like antigen 2 [Fosl2], Oxytocin receptor [Oxtr], and Prostaglandin G/H synthase 2 (Ptgs2), for example), are up-regulated at day 19 during active labor because of an increase in transcription at gene bodies. Labor-associated promoters and putative intergenic enhancers, however, are epigenetically activated as early as day 15, by which point the majority of genome-wide H3K27ac or H3K4me3 peaks present in term laboring tissue is already established. Despite this early exhibited histone signature, increased noncoding enhancer RNA (eRNA) production at putative intergenic enhancers and recruitment of RNAPII to the gene bodies of labor-associated loci were detected only during labor. Our findings indicate that epigenetic activation of the myometrial genome precedes active labor by at least 4 days in the mouse model, suggesting that the myometrium is poised for rapid activation of contraction-associated genes in order to exit the state of quiescence.
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Epigénesis Genética , Sitios Genéticos , Trabajo de Parto/genética , Miometrio/fisiología , Contracción Uterina/genética , Animales , Secuencia de Bases , Femenino , Código de Histonas/genética , Ratones Endogámicos C57BL , Modelos Genéticos , Embarazo , Regiones Promotoras Genéticas , ARN/metabolismo , ARN Polimerasa II/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transcripción Genética , Transcriptoma/genética , Regulación hacia Arriba/genéticaRESUMEN
We have previously shown computationally that Mycolactone (MLN), a toxin produced by Mycobacterium ulcerans, strongly binds to Munc18b and other proteins, presumably blocking degranulation and exocytosis of blood platelets and mast cells. We investigated the effect of MLN on endocytosis using similar approaches, and it bound strongly to the N-terminal of the clathrin protein and a novel SARS-CoV-2 fusion protein. Experimentally, we found 100% inhibition up to 60 nM and 84% average inhibition at 30 nM in SARS-CoV-2 live viral assays. MLN was also 10× more potent than remdesivir and molnupiravir. MLN's toxicity against human alveolar cell line A549, immortalized human fetal renal cell line HEK293, and human hepatoma cell line Huh7.1 were 17.12%, 40.30%, and 36.25%, respectively. The cytotoxicity IC50 breakpoint ratio versus anti-SARS-CoV-2 activity was more than 65-fold. The IC50 values against the alpha, delta, and Omicron variants were all below 0.020 µM, and 134.6 nM of MLN had 100% inhibition in an entry and spread assays. MLN is eclectic in its actions through its binding to Sec61, AT2R, and the novel fusion protein, making it a good drug candidate for treating and preventing COVID-19 and other similarly transmitted enveloped viruses and pathogens.
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COVID-19 , Humanos , SARS-CoV-2 , Antivirales/farmacología , Células HEK293RESUMEN
The Ebola virus (EBOV) is still highly infectious and causes severe hemorrhagic fevers in primates. However, there are no regulatorily approved drugs against the Ebola virus disease (EVD). The highly virulent and lethal nature of EVD highlights the need to develop therapeutic agents. Viral protein 40 kDa (VP40), the most abundantly expressed protein during infection, coordinates the assembly, budding, and release of viral particles into the host cell. It also regulates viral transcription and RNA replication. This study sought to identify small molecules that could potentially inhibit the VP40 protein by targeting the N-terminal domain using an in silico approach. The statistical quality of AutoDock Vina's capacity to discriminate between inhibitors and decoys was determined, and an area under the curve of the receiver operating characteristic (AUC-ROC) curve of 0.791 was obtained. A total of 29,519 natural-product-derived compounds from Chinese and African sources as well as 2738 approved drugs were successfully screened against VP40. Using a threshold of -8 kcal/mol, a total of 7, 11, 163, and 30 compounds from the AfroDb, Northern African Natural Products Database (NANPDB), traditional Chinese medicine (TCM), and approved drugs libraries, respectively, were obtained after molecular docking. A biological activity prediction of the lead compounds suggested their potential antiviral properties. In addition, random-forest- and support-vector-machine-based algorithms predicted the compounds to be anti-Ebola with IC50 values in the micromolar range (less than 25 µM). A total of 42 natural-product-derived compounds were identified as potential EBOV inhibitors with desirable ADMET profiles, comprising 1, 2, and 39 compounds from NANPDB (2-hydroxyseneganolide), AfroDb (ZINC000034518176 and ZINC000095485942), and TCM, respectively. A total of 23 approved drugs, including doramectin, glecaprevir, velpatasvir, ledipasvir, avermectin B1, nafarelin acetate, danoprevir, eltrombopag, lanatoside C, and glycyrrhizin, among others, were also predicted to have potential anti-EBOV activity and can be further explored so that they may be repurposed for EVD treatment. Molecular dynamics simulations coupled with molecular mechanics Poisson-Boltzmann surface area calculations corroborated the stability and good binding affinities of the complexes (-46.97 to -118.9 kJ/mol). The potential lead compounds may have the potential to be developed as anti-EBOV drugs after experimental testing.
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Ebolavirus , Fiebre Hemorrágica Ebola , Animales , Fiebre Hemorrágica Ebola/metabolismo , Proteínas Virales/metabolismo , Simulación del Acoplamiento Molecular , Quimioinformática , Ebolavirus/metabolismoRESUMEN
Malaria affects a significant portion of the global population, with 247 million cases in 2021, primarily in Africa. However, certain hemoglobinopathies, such as sickle cell trait (SCT), have been linked to lower mortality rates in malaria patients. Hemoglobin (Hb) mutations, including HbS and HbC, can cause sickle cell disease (SCD) when both alleles are inherited (HbSS and HbSC). In SCT, one allele is inherited and paired with a normal allele (HbAS, HbAC). The high prevalence of these alleles in Africa may be attributed to their protective effect against malaria. Biomarkers are crucial for SCD and malaria diagnosis and prognosis. Studies indicate that miRNAs, specifically miR-451a and let-7i-5p, are differentially expressed in HbSS and HbAS compared to controls. Our research examined the levels of exosomal miR-451a and let-7i-5p in red blood cells (RBCs) and infected red blood cells (iRBCs) from multiple sickle Hb genotypes and their impact on parasite growth. We assessed exosomal miR-451a and let-7i-5p levels in vitro in RBC and iRBC supernatants. Exosomal miRNAs exhibited distinct expression patterns in iRBCs from individuals with different sickle Hb genotypes. Additionally, we discovered a correlation between let-7i-5p levels and trophozoite count. Exosomal miR-451a and let-7i-5p could modulate SCD and malaria severity and serve as potential biomarkers for malaria vaccines and therapies.
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Anemia de Células Falciformes , Malaria , MicroARNs , Parásitos , Rasgo Drepanocítico , Animales , Humanos , Parásitos/metabolismo , Hemoglobinas/metabolismo , Hemoglobina Falciforme/genética , Hemoglobina Falciforme/metabolismo , MicroARNs/genética , Genotipo , Anemia de Células Falciformes/genética , Rasgo Drepanocítico/genética , Biomarcadores , Hemoglobina A/genética , Malaria/genéticaRESUMEN
The role of the microbiota-gut-brain (MGB) axis in mood regulation and depression treatment has gained attention in recent years, as evidenced by the growing number of animal and human studies that have reported the anti-depressive and associated gamma-aminobutyric acid-ergic (GABAergic) effects of probiotics developed from Lactobacillus rhamnosus bacterial strains in the gut microbiome. The depressive states attenuated by these probiotics in patients suffering from clinical depression also characterize the severe and relapse-inducing withdrawal phase of the addiction cycle, which has been found to arise from the intoxication-enabled hyperregulation of the hypothalamic-pituitary-adrenal (HPA) axis, the body's major stress response system, and a corresponding attenuation of its main inhibitory system, the gamma-aminobutyric acid (GABA) signaling system. Therefore, the use of probiotics in the treatment of general cases of depression provides hope for a novel therapeutic approach to withdrawal depression remediation. This review discusses potential therapeutic avenues by which probiotic application of Lactobacillus rhamnosus strains can be used to restore the central GABAergic activity responsible for attenuating the depression-inducing HPA axis hyperactivity in addiction withdrawal. Also, information is provided on brain GABAergic signaling from other known GABA-producing strains of gut microbiota.
RESUMEN
Diabetes mellitus is a disorder characterized by higher levels of blood glucose due to impaired insulin mechanisms. Alpha glucosidase is a critical drug target implicated in the mechanisms of diabetes mellitus and its inhibition controls hyperglycemia. Since the existing standard synthetic drugs have therapeutic limitations, it is imperative to identify new potent inhibitors of natural product origin which may slow carbohydrate digestion and absorption via alpha glucosidase. Since plant extracts from Calotropis procera have been extensively used in the treatment of diabetes mellitus, the present study used molecular docking and dynamics simulation techniques to screen its constituents against the receptor alpha glucosidase. Taraxasterol, syriogenin, isorhamnetin-3-O-robinobioside and calotoxin were identified as potential novel lead compounds with plausible binding energies of -40.2, -35.1, -34.3 and -34.3 kJ/mol against alpha glucosidase, respectively. The residues Trp481, Asp518, Leu677, Leu678 and Leu680 were identified as critical for binding and the compounds were predicted as alpha glucosidase inhibitors. Structurally similar compounds with Tanimoto coefficients greater than 0.7 were reported experimentally to be inhibitors of alpha glucosidase or antidiabetic. The structures of the molecules may serve as templates for the design of novel inhibitors and warrant in vitro assaying to corroborate their antidiabetic potential.
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PURPOSE: RABGAP1 is a GTPase-activating protein implicated in a variety of cellular and molecular processes, including mitosis, cell migration, vesicular trafficking, and mTOR signaling. There are no known Mendelian diseases caused by variants in RABGAP1. METHODS: Through GeneMatcher, we identified 5 patients from 3 unrelated families with homozygous variants in the RABGAP1 gene found on exome sequencing. We established lymphoblastoid cells lines derived from an affected individual and her parents and performed RNA sequencing and functional studies. Rabgap1 knockout mice were generated and phenotyped. RESULTS: We report 5 patients presenting with a common constellation of features, including global developmental delay/intellectual disability, microcephaly, bilateral sensorineural hearing loss, and seizures, as well as overlapping dysmorphic features. Neuroimaging revealed common features, including delayed myelination, white matter volume loss, ventriculomegaly, and thinning of the corpus callosum. Functional analysis of patient cells revealed downregulated mTOR signaling and abnormal localization of early endosomes and lysosomes. Rabgap1 knockout mice exhibited several features in common with the patient cohort, including microcephaly, thinning of the corpus callosum, and ventriculomegaly. CONCLUSION: Collectively, our results provide evidence of a novel neurodevelopmental syndrome caused by biallelic loss-of-function variants in RABGAP1.
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Hidrocefalia , Discapacidad Intelectual , Microcefalia , Trastornos del Neurodesarrollo , Animales , Ratones , Femenino , Humanos , Microcefalia/genética , Linaje , Discapacidad Intelectual/genética , Síndrome , Ratones Noqueados , Serina-Treonina Quinasas TOR , Trastornos del Neurodesarrollo/genéticaRESUMEN
Quebec platelet disorder (QPD) is an autosomal dominant bleeding disorder with a unique, platelet-dependent, gain-of-function defect in fibrinolysis, without systemic fibrinolysis. The hallmark feature of QPD is a >100-fold overexpression of PLAU, specifically in megakaryocytes. This overexpression leads to a >100-fold increase in platelet stores of urokinase plasminogen activator (PLAU/uPA); subsequent plasmin-mediated degradation of diverse α-granule proteins; and platelet-dependent, accelerated fibrinolysis. The causative mutation is a 78-kb tandem duplication of PLAU. How this duplication causes megakaryocyte-specific PLAU overexpression is unknown. To investigate the mechanism that causes QPD, we used epigenomic profiling, comparative genomics, and chromatin conformation capture approaches to study PLAU regulation in cultured megakaryocytes from participants with QPD and unaffected controls. QPD duplication led to ectopic interactions between PLAU and a conserved megakaryocyte enhancer found within the same topologically associating domain (TAD). Our results support a unique disease mechanism whereby the reorganization of sub-TAD genome architecture results in a dramatic, cell-type-specific blood disorder phenotype.
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Elementos de Facilitación Genéticos , Deficiencia del Factor V , Duplicación de Gen , Regulación de la Expresión Génica , Megacariocitos/metabolismo , Proteínas de la Membrana , Animales , Deficiencia del Factor V/genética , Deficiencia del Factor V/metabolismo , Deficiencia del Factor V/patología , Femenino , Humanos , Megacariocitos/patología , Proteínas de la Membrana/biosíntesis , Proteínas de la Membrana/genética , Pez CebraRESUMEN
X-linked myotubular myopathy (XLMTM) is a fatal neuromuscular disorder caused by loss of function mutations in MTM1. At present, there are no directed therapies for XLMTM, and incomplete understanding of disease pathomechanisms. To address these knowledge gaps, we performed a drug screen in mtm1 mutant zebrafish and identified four positive hits, including valproic acid, which functions as a potent suppressor of the mtm1 zebrafish phenotype via HDAC inhibition. We translated these findings to a mouse XLMTM model, and showed that valproic acid ameliorates the murine phenotype. These observations led us to interrogate the epigenome in Mtm1 knockout mice; we found increased DNA methylation, which is normalized with valproic acid, and likely mediated through aberrant 1-carbon metabolism. Finally, we made the unexpected observation that XLMTM patients share a distinct DNA methylation signature, suggesting that epigenetic alteration is a conserved disease feature amenable to therapeutic intervention.
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Miopatías Estructurales Congénitas , Pez Cebra , Animales , Modelos Animales de Enfermedad , Epigénesis Genética , Ratones , Músculo Esquelético/metabolismo , Miopatías Estructurales Congénitas/tratamiento farmacológico , Miopatías Estructurales Congénitas/genética , Miopatías Estructurales Congénitas/metabolismo , Proteínas Tirosina Fosfatasas no Receptoras/genética , Proteínas Tirosina Fosfatasas no Receptoras/metabolismo , Ácido Valproico/metabolismo , Ácido Valproico/farmacología , Pez Cebra/metabolismoRESUMEN
RATIONALE: The development and function of the pacemaker cardiomyocytes of the sinoatrial node (SAN), the leading pacemaker of the heart, are tightly controlled by a conserved network of transcription factors, including TBX3 (T-box transcription factor 3), ISL1 (ISL LIM homeobox 1), and SHOX2 (short stature homeobox 2). Yet, the regulatory DNA elements (REs) controlling target gene expression in the SAN pacemaker cells have remained undefined. OBJECTIVE: Identification of the regulatory landscape of human SAN-like pacemaker cells and functional assessment of SAN-specific REs potentially involved in pacemaker cell gene regulation. METHODS AND RESULTS: We performed Assay for Transposase-Accessible Chromatin using sequencing on human pluripotent stem cell-derived SAN-like pacemaker cells and ventricle-like cells and identified thousands of putative REs specific for either human cell type. We validated pacemaker cell-specific elements in the SHOX2 and TBX3 loci. CRISPR-mediated homozygous deletion of the mouse ortholog of a noncoding region with candidate pacemaker-specific REs in the SHOX2 locus resulted in selective loss of Shox2 expression from the developing SAN and embryonic lethality. Putative pacemaker-specific REs were identified up to 1 Mbp upstream of TBX3 in a region close to MED13L harboring variants associated with heart rate recovery after exercise. The orthologous region was deleted in mice, which resulted in selective loss of expression of Tbx3 from the SAN and (cardiac) ganglia and in neonatal lethality. Expression of Tbx3 was maintained in other tissues including the atrioventricular conduction system, lungs, and liver. Heterozygous adult mice showed increased SAN recovery times after pacing. The human REs harboring the associated variants robustly drove expression in the SAN of transgenic mouse embryos. CONCLUSIONS: We provided a genome-wide collection of candidate human pacemaker-specific REs, including the loci of SHOX2, TBX3, and ISL1, and identified a link between human genetic variants influencing heart rate recovery after exercise and a variant RE with highly conserved function, driving SAN expression of TBX3.
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Relojes Biológicos , Elementos de Facilitación Genéticos , Frecuencia Cardíaca , Miocitos Cardíacos/metabolismo , Nodo Sinoatrial/metabolismo , Proteínas de Dominio T Box/metabolismo , Potenciales de Acción , Animales , Línea Celular , Epigénesis Genética , Femenino , Regulación del Desarrollo de la Expresión Génica , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Ratones Transgénicos , Mutación , Proteínas de Dominio T Box/genética , Pez CebraRESUMEN
BACKGROUND: Malaria related mortality is associated with significant deregulation of host inflammatory factors such as interferon-inducible protein 10, a member of the CXC or α-subfamily (CXCL10), and host angiogenic factors such as angiopoietin 1 (Ang-1) and angiopoietin 2 (Ang-2). However, detection of these factors in malaria patients requires the drawing of blood, which is invasive and increases the risk of accidental blood-borne infections. There has been an increased interest in the use of saliva as the body fluid of choice for the diagnosis of many infectious diseases including malaria. Here, saliva levels of CXCL10, Ang-1, and Ang-2 previously shown to be predictive of severe malaria in malaria patients in Ghana were assessed in malaria patients. METHODS: This study was conducted in the Shai-Osudoku District Hospital in Dodowa, Accra, Ghana and the study population comprised 119 malaria patients and 94 non-malaria subjects. The non-malaria subjects are healthy community participants with no malaria infection. Plasma and saliva levels of CXCL10, Ang-1 and Ang-2 of the study participants were measured using an enzyme-linked immunoassay. Complete blood counts of each participant were measured with a haematology autoanalyzer. Pearson correlation was used to evaluate the correlation between plasma and saliva levels of each biomarker in malaria patients. A p-value of < 0.05 was considered significant. Box plots of median biomarker concentrations were plotted. SPSS version 14.2 software was used for statistical analysis. RESULTS: The non-malaria subjects had a median age of 29 years compared to 23 years for malaria patients (p = 0.001). Among the malaria patients, there was a strong significant relationship between CXCL10 (R2 = 0.7, p < 0.0001) and Ang-1 (R2 = 0.7, p < 0.0001). Malaria patients had lower saliva levels of Ang-1 (p = 0.009) and higher saliva levels of CXCL10 (p = 0.004) and Ang-2 (p = 0.001) compared to non-malaria subjects. CONCLUSIONS: This study provides the first evidence of elevated levels of CXCL10 and Ang-2 in the saliva of malaria patients. Detection of CXCL10, Ang-1 and Ang-2 in saliva may have a potential application for non-invasive malaria diagnosis.