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1.
Commun Biol ; 7(1): 529, 2024 May 04.
Artículo en Inglés | MEDLINE | ID: mdl-38704509

RESUMEN

Intra-organism biodiversity is thought to arise from epigenetic modification of constituent genes and post-translational modifications of translated proteins. Here, we show that post-transcriptional modifications, like RNA editing, may also contribute. RNA editing enzymes APOBEC3A and APOBEC3G catalyze the deamination of cytosine to uracil. RNAsee (RNA site editing evaluation) is a computational tool developed to predict the cytosines edited by these enzymes. We find that 4.5% of non-synonymous DNA single nucleotide polymorphisms that result in cytosine to uracil changes in RNA are probable sites for APOBEC3A/G RNA editing; the variant proteins created by such polymorphisms may also result from transient RNA editing. These polymorphisms are associated with over 20% of Medical Subject Headings across ten categories of disease, including nutritional and metabolic, neoplastic, cardiovascular, and nervous system diseases. Because RNA editing is transient and not organism-wide, future work is necessary to confirm the extent and effects of such editing in humans.


Asunto(s)
Desaminasas APOBEC , Citidina Desaminasa , Edición de ARN , Humanos , Citidina Desaminasa/metabolismo , Citidina Desaminasa/genética , Polimorfismo de Nucleótido Simple , Citosina/metabolismo , Desaminasa APOBEC-3G/metabolismo , Desaminasa APOBEC-3G/genética , Uracilo/metabolismo , Proteínas/genética , Proteínas/metabolismo , Citosina Desaminasa/genética , Citosina Desaminasa/metabolismo
2.
Nat Commun ; 15(1): 4002, 2024 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-38734692

RESUMEN

Precise genome editing is crucial for establishing isogenic human disease models and ex vivo stem cell therapy from the patient-derived hPSCs. Unlike Cas9-mediated knock-in, cytosine base editor and prime editor achieve the desirable gene correction without inducing DNA double strand breaks. However, hPSCs possess highly active DNA repair pathways and are particularly susceptible to p53-dependent cell death. These unique characteristics impede the efficiency of gene editing in hPSCs. Here, we demonstrate that dual inhibition of p53-mediated cell death and distinct activation of the DNA damage repair system upon DNA damage by cytosine base editor or prime editor additively enhanced editing efficiency in hPSCs. The BE4stem system comprised of p53DD, a dominant negative p53, and three UNG inhibitor, engineered to specifically diminish base excision repair, improves cytosine base editor efficiency in hPSCs. Addition of dominant negative MLH1 to inhibit mismatch repair activity and p53DD in the conventional prime editor system also significantly enhances prime editor efficiency in hPSCs. Thus, combined inhibition of the distinct cellular cascades engaged in hPSCs upon gene editing could significantly enhance precise genome editing in these cells.


Asunto(s)
Sistemas CRISPR-Cas , Daño del ADN , Reparación del ADN , Edición Génica , Proteína p53 Supresora de Tumor , Edición Génica/métodos , Humanos , Proteína p53 Supresora de Tumor/metabolismo , Proteína p53 Supresora de Tumor/genética , Línea Celular , Homólogo 1 de la Proteína MutL/genética , Homólogo 1 de la Proteína MutL/metabolismo , Citosina/metabolismo
3.
Nat Commun ; 15(1): 3635, 2024 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-38688903

RESUMEN

Although intratumoral heterogeneity has been established in pediatric central nervous system tumors, epigenomic alterations at the cell type level have largely remained unresolved. To identify cell type-specific alterations to cytosine modifications in pediatric central nervous system tumors, we utilize a multi-omic approach that integrated bulk DNA cytosine modification data (methylation and hydroxymethylation) with both bulk and single-cell RNA-sequencing data. We demonstrate a large reduction in the scope of significantly differentially modified cytosines in tumors when accounting for tumor cell type composition. In the progenitor-like cell types of tumors, we identify a preponderance differential Cytosine-phosphate-Guanine site hydroxymethylation rather than methylation. Genes with differential hydroxymethylation, like histone deacetylase 4 and insulin-like growth factor 1 receptor, are associated with cell type-specific changes in gene expression in tumors. Our results highlight the importance of epigenomic alterations in the progenitor-like cell types and its role in cell type-specific transcriptional regulation in pediatric central nervous system tumors.


Asunto(s)
Neoplasias del Sistema Nervioso Central , Metilación de ADN , Epigénesis Genética , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias del Sistema Nervioso Central/genética , Neoplasias del Sistema Nervioso Central/metabolismo , Neoplasias del Sistema Nervioso Central/patología , Niño , Histona Desacetilasas/metabolismo , Histona Desacetilasas/genética , Epigenómica/métodos , Proteínas Represoras/metabolismo , Proteínas Represoras/genética , Análisis de la Célula Individual , Transcripción Genética , Citosina/metabolismo
4.
PLoS One ; 19(4): e0297008, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38635731

RESUMEN

Methylation and hydroxymethylation of cytosine moieties in CpG islands of specific genes are epigenetic processes shown to be involved in the development of cervical (pre)neoplastic lesions. We studied global (hydroxy)methylation during the subsequent steps in the carcinogenic process of the uterine cervix by using immunohistochemical protocols for the detection of 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) in paraffin-embedded tissues of the normal epithelia and (pre)malignant lesions. This approach allowed obtaining spatially resolved information of (epi)genetic alterations for individual cell populations in morphologically heterogeneous tissue samples. The normal ectocervical squamous epithelium showed a high degree of heterogeneity for both modifications, with a major positivity for 5-mC in the basal and parabasal layers in the ectocervical region, while 5-hmC immunostaining was even more restricted to the cells in the basal layer. Immature squamous metaplasia, characterized by expression of SOX17, surprisingly showed a decrease of 5-hmC in the basal compartments and an increase in the more superficial layers of the epithelium. The normal endocervical glandular epithelium showed a strong immunostaining reactivity for both modifications. At the squamocolumnar junctions, a specific 5-hmC pattern was observed in the squamous epithelium, resembling that of metaplasia, with the typical weak to negative reaction for 5-hmC in the basal cell compartment. The reserve cells underlying the glandular epithelium were also largely negative for 5-hmC but showed immunostaining for 5-mC. While the overall methylation status remained relatively constant, about 20% of the high-grade squamous lesions showed a very low immunostaining reactivity for 5-hmC. The (pre)malignant glandular lesions, including adenocarcinoma in situ (AIS) and adenocarcinoma showed a progressive decrease of hydroxymethylation with advancement of the lesion, resulting in cases with regions that were negative for 5-hmC immunostaining. These data indicate that inhibition of demethylation, which normally follows cytosine hydroxymethylation, is an important epigenetic switch in the development of cervical cancer.


Asunto(s)
Carcinoma de Células Escamosas , Neoplasias del Cuello Uterino , Femenino , Humanos , Citosina/metabolismo , Neoplasias del Cuello Uterino/patología , Cuello del Útero/patología , 5-Metilcitosina/metabolismo , Metilación de ADN , Carcinoma de Células Escamosas/patología , Metaplasia/patología
5.
BMC Biol ; 22(1): 99, 2024 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-38679734

RESUMEN

BACKGROUND: TALE-derived DddA-based cytosine base editors (TALE-DdCBEs) can perform efficient base editing of mitochondria and chloroplast genomes. They use transcription activator-like effector (TALE) arrays as programmable DNA-binding domains and a split version of the double-strand DNA cytidine deaminase (DddA) to catalyze C•G-to-T•A editing. This technology has not been optimized for use in plant cells. RESULTS: To systematically investigate TALE-DdCBE architectures and editing rules, we established a ß-glucuronidase reporter for transient assays in Nicotiana benthamiana. We show that TALE-DdCBEs function with distinct spacer lengths between the DNA-binding sites of their two TALE parts. Compared to canonical DddA, TALE-DdCBEs containing evolved DddA variants (DddA6 or DddA11) showed a significant improvement in editing efficiency in Nicotiana benthamiana and rice. Moreover, TALE-DdCBEs containing DddA11 have broader sequence compatibility for non-TC target editing. We have successfully regenerated rice with C•G-to-T•A conversions in their chloroplast genome, as well as N. benthamiana with C•G-to-T•A editing in the nuclear genome using TALE-DdCBE. We also found that the spontaneous assembly of split DddA halves can cause undesired editing by TALE-DdCBEs in plants. CONCLUSIONS: Altogether, our results refined the targeting scope of TALE-DdCBEs and successfully applied them to target the chloroplast and nuclear genomes. Our study expands the base editing toolbox in plants and further defines parameters to optimize TALE-DdCBEs for high-fidelity crop improvement.


Asunto(s)
Edición Génica , Nicotiana , Edición Génica/métodos , Nicotiana/genética , Efectores Tipo Activadores de la Transcripción/metabolismo , Efectores Tipo Activadores de la Transcripción/genética , Citidina Desaminasa/metabolismo , Citidina Desaminasa/genética , Citosina/metabolismo , Oryza/genética
6.
EMBO J ; 43(8): 1445-1483, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38499786

RESUMEN

Regulatory T (TREG) cells develop via a program orchestrated by the transcription factor forkhead box protein P3 (FOXP3). Maintenance of the TREG cell lineage relies on sustained FOXP3 transcription via a mechanism involving demethylation of cytosine-phosphate-guanine (CpG)-rich elements at conserved non-coding sequences (CNS) in the FOXP3 locus. This cytosine demethylation is catalyzed by the ten-eleven translocation (TET) family of dioxygenases, and it involves a redox reaction that uses iron (Fe) as an essential cofactor. Here, we establish that human and mouse TREG cells express Fe-regulatory genes, including that encoding ferritin heavy chain (FTH), at relatively high levels compared to conventional T helper cells. We show that FTH expression in TREG cells is essential for immune homeostasis. Mechanistically, FTH supports TET-catalyzed demethylation of CpG-rich sequences CNS1 and 2 in the FOXP3 locus, thereby promoting FOXP3 transcription and TREG cell stability. This process, which is essential for TREG lineage stability and function, limits the severity of autoimmune neuroinflammation and infectious diseases, and favors tumor progression. These findings suggest that the regulation of intracellular iron by FTH is a stable property of TREG cells that supports immune homeostasis and limits the pathological outcomes of immune-mediated inflammation.


Asunto(s)
Apoferritinas , Linfocitos T Reguladores , Animales , Humanos , Ratones , Apoferritinas/genética , Apoferritinas/metabolismo , Linaje de la Célula/genética , Citosina/metabolismo , Factores de Transcripción Forkhead , Hierro/metabolismo
7.
Anal Chem ; 96(11): 4726-4735, 2024 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-38450632

RESUMEN

DNA cytosine methylation (5-methylcytosine, 5mC) is a predominant epigenetic modification that plays a critical role in a variety of biological and pathological processes in mammals. In active DNA demethylation, the 10-11 translocation (TET) dioxygenases can sequentially oxidize 5mC to generate three modified forms of cytosine, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). Beyond being a demethylation intermediate, recent studies have shown that 5fC has regulatory functions in gene expression and chromatin organization. While some methods have been developed to detect 5fC, genome-wide mapping of 5fC at base resolution is still highly desirable. Herein, we propose a chemical labeling enrichment and deamination sequencing (CLED-seq) method for detecting 5fC in genomic DNA at single-base resolution. The CLED-seq method utilizes selective labeling and enrichment of 5fC-containing DNA fragments, followed by deamination mediated by apolipoprotein B mRNA-editing catalytic polypeptide-like 3A (APOBEC3A or A3A) and sequencing. In the CLED-seq process, while all C, 5mC, and 5hmC are interpreted as T during sequencing, 5fC is still read as C, enabling the precise detection of 5fC in DNA. Using the proposed CLED-seq method, we accomplished genome-wide mapping of 5fC in mouse embryonic stem cells. The mapping study revealed that promoter regions enriched with 5fC overlapped with H3K4me1, H3K4me3, and H3K27ac marks. These findings suggest a correlation between 5fC marks and active gene expression in mESCs. In conclusion, CLED-seq is a straightforward, bisulfite-free method that offers a valuable tool for detecting 5fC in genomes at a single-base resolution.


Asunto(s)
Citidina Desaminasa , Citosina , Citosina/análogos & derivados , Epigénesis Genética , Proteínas , Animales , Ratones , Desaminación , Citosina/metabolismo , 5-Metilcitosina/metabolismo , Mapeo Cromosómico , ADN/genética , ADN/metabolismo , Metilación de ADN , Mamíferos/metabolismo
8.
Nat Commun ; 15(1): 2369, 2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38499553

RESUMEN

The APOBEC3 enzymes convert cytosines in single-stranded DNA to uracils to protect against viruses and retrotransposons but can contribute to mutations that diversify tumors. To understand the mechanism of mutagenesis, we map the uracils resulting from expression of APOBEC3B or its catalytic carboxy-terminal domain (CTD) in Escherichia coli. Like APOBEC3A, the uracilomes of A3B and A3B-CTD show a preference to deaminate cytosines near transcription start sites and the lagging-strand replication templates and in hairpin loops. Both biochemical activities of the enzymes and genomic uracil distribution show that A3A prefers 3 nt loops the best, while A3B prefers 4 nt loops. Reanalysis of hairpin loop mutations in human tumors finds intrinsic characteristics of both the enzymes, with a much stronger contribution from A3A. We apply Hairpin Signatures 1 and 2, which define A3A and A3B preferences respectively and are orthogonal to published methods, to evaluate their contribution to human tumor mutations.


Asunto(s)
Citosina , Neoplasias , Humanos , Citosina/metabolismo , Proteínas/metabolismo , Mutación , Citidina Desaminasa/metabolismo , Neoplasias/genética , Uracilo/metabolismo , Antígenos de Histocompatibilidad Menor/metabolismo
9.
J Biol Chem ; 300(4): 105786, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38401843

RESUMEN

Histone proteins can become trapped on DNA in the presence of 5-formylcytosine (5fC) to form toxic DNA-protein conjugates. Their repair may involve proteolytic digestion resulting in DNA-peptide cross-links (DpCs). Here, we have investigated replication of a model DpC comprised of an 11-mer peptide (NH2-GGGKGLGK∗GGA) containing an oxy-lysine residue (K∗) conjugated to 5fC in DNA. Both CXG and CXT (where X = 5fC-DpC) sequence contexts were examined. Replication of both constructs gave low viability (<10%) in Escherichia coli, whereas TLS efficiency was high (72%) in HEK 293T cells. In E. coli, the DpC was bypassed largely error-free, inducing only 2 to 3% mutations, which increased to 4 to 5% with SOS. For both sequences, semi-targeted mutations were dominant, and for CXG, the predominant mutations were G→T and G→C at the 3'-base to the 5fC-DpC. In HEK 293T cells, 7 to 9% mutations occurred, and the dominant mutations were the semi-targeted G → T for CXG and T → G for CXT. These mutations were reduced drastically in cells deficient in hPol η, hPol ι or hPol ζ, suggesting a role of these TLS polymerases in mutagenic TLS. Steady-state kinetics studies using hPol η confirmed that this polymerase induces G → T and T → G transversions at the base immediately 3' to the DpC. This study reveals a unique replication pattern of 5fC-conjugated DpCs, which are bypassed largely error-free in both E. coli and human cells and induce mostly semi-targeted mutations at the 3' position to the lesion.


Asunto(s)
Citosina , Citosina/análogos & derivados , ADN , Escherichia coli , Mutación , Humanos , Escherichia coli/metabolismo , Escherichia coli/genética , Células HEK293 , Citosina/metabolismo , Citosina/química , ADN/metabolismo , ADN/química , Péptidos/química , Péptidos/metabolismo , Péptidos/farmacología , Replicación del ADN/efectos de los fármacos
10.
PLoS One ; 19(2): e0293894, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38381741

RESUMEN

Modifications of mRNA, especially methylation of adenosine, have recently drawn much attention. The much rarer modification, 5-hydroxymethylation of cytosine (5hmC), is not well understood and is the subject of this study. Vertebrate Tet proteins are 5-methylcytosine (5mC) hydroxylases and catalyze the transition of 5mC to 5hmC in DNA. These enzymes have recently been shown to have the same function in messenger RNAs in both vertebrates and in Drosophila. The Tet gene is essential in Drosophila as Tet knock-out animals do not reach adulthood. We describe the identification of Tet-target genes in the embryo and larval brain by mapping one, Tet DNA-binding sites throughout the genome and two, the Tet-dependent 5hmrC modifications transcriptome-wide. 5hmrC modifications are distributed along the entire transcript, while Tet DNA-binding sites are preferentially located at the promoter where they overlap with histone H3K4me3 peaks. The identified mRNAs are preferentially involved in neuron and axon development and Tet knock-out led to a reduction of 5hmrC marks on specific mRNAs. Among the Tet-target genes were the robo2 receptor and its slit ligand that function in axon guidance in Drosophila and in vertebrates. Tet knock-out embryos show overlapping phenotypes with robo2 and both Robo2 and Slit protein levels were markedly reduced in Tet KO larval brains. Our results establish a role for Tet-dependent 5hmrC in facilitating the translation of modified mRNAs primarily in cells of the nervous system.


Asunto(s)
Citosina , Dioxigenasas , Animales , Citosina/metabolismo , Drosophila/genética , Drosophila/metabolismo , Metilación de ADN , ARN Mensajero/genética , ARN Mensajero/metabolismo , Orientación del Axón , Proteínas de Unión al ADN/metabolismo , 5-Metilcitosina/metabolismo , ADN/metabolismo , Dioxigenasas/genética
11.
Nucleic Acids Res ; 52(5): e24, 2024 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-38261991

RESUMEN

Hemi-methylated cytosine dyads widely occur on mammalian genomic DNA, and can be stably inherited across cell divisions, serving as potential epigenetic marks. Previous identification of hemi-methylation relied on harsh bisulfite treatment, leading to extensive DNA degradation and loss of methylation information. Here we introduce Mhemi-seq, a bisulfite-free strategy, to efficiently resolve methylation status of cytosine dyads into unmethylation, strand-specific hemi-methylation, or full-methylation. Mhemi-seq reproduces methylomes from bisulfite-based sequencing (BS-seq & hpBS-seq), including the asymmetric hemi-methylation enrichment flanking CTCF motifs. By avoiding base conversion, Mhemi-seq resolves allele-specific methylation and associated imprinted gene expression more efficiently than BS-seq. Furthermore, we reveal an inhibitory role of hemi-methylation in gene expression and transcription factor (TF)-DNA binding, and some displays a similar extent of inhibition as full-methylation. Finally, we uncover new hemi-methylation patterns within Alu retrotransposon elements. Collectively, Mhemi-seq can accelerate the identification of DNA hemi-methylation and facilitate its integration into the chromatin environment for future studies.


Asunto(s)
Metilación de ADN , Análisis de Secuencia de ADN , Animales , Citosina/metabolismo , Metilación de ADN/genética , Mamíferos/genética , Retroelementos , Análisis de Secuencia de ADN/métodos , Sulfitos , Regulación de la Expresión Génica
12.
Chem Soc Rev ; 53(5): 2264-2283, 2024 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-38205583

RESUMEN

Epigenetic phenomena play a central role in cell regulatory processes and are important factors for understanding complex human disease. One of the best understood epigenetic mechanisms is DNA methylation. In the mammalian genome, cytosines (C) in CpG dinucleotides were long known to undergo methylation at the 5-position of the pyrimidine ring (mC). Later it was found that mC can be oxidized to 5-hydroxymethylcytosine (hmC) or even further to 5-formylcytosine (fC) and to 5-carboxylcytosine (caC) by the action of 2-oxoglutarate-dependent dioxygenases of the TET family. These findings unveiled a long elusive mechanism of active DNA demethylation and bolstered a wave of studies in the area of epigenetic regulation in mammals. This review is dedicated to critical assessment of recent data on biochemical and chemical aspects of the formation and conversion of hmC in DNA, analytical techniques used for detection and mapping of this nucleobase in mammalian genomes as well as epigenetic roles of hmC in DNA replication, transcription, cell differentiation and human disease.


Asunto(s)
5-Metilcitosina , 5-Metilcitosina/análogos & derivados , Epigénesis Genética , Animales , Humanos , 5-Metilcitosina/metabolismo , Citosina/metabolismo , ADN/genética , ADN/metabolismo , Mamíferos/genética , Mamíferos/metabolismo
13.
Life Sci Alliance ; 7(4)2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38233073

RESUMEN

DNA methylation is an essential epigenetic mechanism that regulates cellular reprogramming and development. Studies using whole-genome bisulfite sequencing have revealed distinct DNA methylome landscapes in human and mouse cells and tissues. However, the factors responsible for the differences in megabase-scale methylome patterns between cell types remain poorly understood. By analyzing publicly available 258 human and 301 mouse whole-genome bisulfite sequencing datasets, we reveal that genomic regions rich in guanine and cytosine, when located near the nuclear center, are highly susceptible to both global DNA demethylation and methylation events during embryonic and germline reprogramming. Furthermore, we found that regions that generate partially methylated domains during global DNA methylation are more likely to resist global DNA demethylation, contain high levels of adenine and thymine, and are adjacent to the nuclear lamina. The spatial properties of genomic regions, influenced by their guanine-cytosine content, are likely to affect the accessibility of molecules involved in DNA (de)methylation. These properties shape megabase-scale DNA methylation patterns and change as cells differentiate, leading to the emergence of different megabase-scale methylome patterns across cell types.


Asunto(s)
Metilación de ADN , Epigenoma , Sulfitos , Humanos , Animales , Ratones , Metilación de ADN/genética , Epigenoma/genética , Citosina/metabolismo , Guanina
14.
Chem Asian J ; 19(3): e202301005, 2024 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-38206202

RESUMEN

Chemical modifications to Cytosine bases are among the most studied epigenetic markers and their detection in the human genome plays a crucial role in gaining more insights about gene regulation, prognosis of genetic disorders and unraveling genetic inheritance patterns. The Cytosine methylated at the 5th position and oxidized derivatives thereof generated in the demethylation pathways, perform separate and unique epigenetic functions in an organism. As the presence of various Cytosine modifications is associated with diverse diseases, including cancer, there has been a strong focus on developing methods, both chemical and alternative approaches, capable of detecting these modifications at a single-base resolution across the entire genome. In this comprehensive review, we aim to consolidate the various chemical methods and understanding their chemistry that have been established to date for the detection of various Cytosine modifications.


Asunto(s)
Citosina , Neoplasias , Humanos , Citosina/metabolismo , Metilación de ADN , Epigénesis Genética
15.
Neuropsychopharmacol Rep ; 44(1): 250-255, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38058257

RESUMEN

Quantifying cytosine modifications in various brain regions provides important insights into the gene expression regulation and pathophysiology of neuropsychiatric disorders. In this study, we quantified 5-methylcytosine (5-mC), 5-hydroxymethylation (5-hmC), and 5-formylcytosine (5-fC) levels in five brain regions (the frontal lobe, cerebral cortical region without frontal lobe, hippocampus, basal ganglia, and the cerebellum) and the heart at three developmental periods (12, 48, and 101 weeks). We observed significant regional variations in cytosine modification. Notably, regional variations were generally maintained throughout development, suggesting that epigenetic regulation is unique to each brain region and remains relatively stable with age. The 5-mC and 5-hmC levels were positively correlated, although the extent of the correlations seemed to differ in different brain regions. On the contrary, 5-fC levels did not correlate with 5-mC or 5-hmC levels. Additionally, we observed an age-dependent decrease in 5-fC levels in the basal ganglia, suggesting a unique epigenetic regulation mechanism. Further high-resolution studies using animal models of neuropsychiatric disorders as well as postmortem brain evaluation are warranted.


Asunto(s)
Citosina , Epigénesis Genética , Animales , Ratones , Citosina/metabolismo , 5-Metilcitosina/metabolismo , Encéfalo/metabolismo , Cerebelo/metabolismo
16.
Nat Biotechnol ; 42(4): 638-650, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37322276

RESUMEN

Base editors have substantial promise in basic research and as therapeutic agents for the correction of pathogenic mutations. The development of adenine transversion editors has posed a particular challenge. Here we report a class of base editors that enable efficient adenine transversion, including precise A•T-to-C•G editing. We found that a fusion of mouse alkyladenine DNA glycosylase (mAAG) with nickase Cas9 and deaminase TadA-8e catalyzed adenosine transversion in specific sequence contexts. Laboratory evolution of mAAG significantly increased A-to-C/T conversion efficiency up to 73% and expanded the targeting scope. Further engineering yielded adenine-to-cytosine base editors (ACBEs), including a high-accuracy ACBE-Q variant, that precisely install A-to-C transversions with minimal Cas9-independent off-targeting effects. ACBEs mediated high-efficiency installation or correction of five pathogenic mutations in mouse embryos and human cell lines. Founder mice showed 44-56% average A-to-C edits and allelic frequencies of up to 100%. Adenosine transversion editors substantially expand the capabilities and possible applications of base editing technology.


Asunto(s)
Adenina , Edición Génica , Animales , Ratones , Humanos , Adenina/metabolismo , Mutación , Citosina/metabolismo , Adenosina , Sistemas CRISPR-Cas/genética , Mamíferos/genética
17.
Genome ; 67(1): 1-12, 2024 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-37746933

RESUMEN

Mobilization of transposable elements (TEs) is suppressed by epigenetic mechanisms involving cytosine methylation. However, few studies have focused on clarifying relationships between epigenetic influences of TEs on the adjacent DNA regions and time after insertion of TEs into the genome and/or their chromosomal location. Here we addressed these issues using soybean retrotransposon SORE-1. We analyzed SORE-1, inserted in exon 1 of the GmphyA2 gene, one of the newest insertions in this family so far identified. Cytosine methylation was detected in this element but was barely present in the adjacent regions. These results were correlated, respectively, with the presence and absence of the production of short interfering RNAs. Cytosine methylation profiles of 74 SORE-1 elements in the Williams 82 reference genome indicated that methylation frequency in the adjacent regions of SORE-1 was profoundly higher in pericentromeric regions than in euchromatic chromosome arms and was only weakly correlated with the length of time after insertion into the genome. Notably, the higher level of methylation in the 5' adjacent regions of SORE-1 coincided with the presence of repetitive elements in pericentromeric regions. Together, these results suggest that epigenetic influence of SORE-1 on the adjacent regions is influenced by its location on the chromosome.


Asunto(s)
Glycine max , Retroelementos , Glycine max/genética , Metilación de ADN , Cromosomas , Citosina/metabolismo , Elementos Transponibles de ADN
18.
ACS Nano ; 18(2): 1496-1503, 2024 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-38157484

RESUMEN

We develop a DNA origami-based internal kinetic referencing system with a colocalized reference and target molecule to provide increased sensitivity and robustness for transient binding kinetics. To showcase this, we investigate the subtle changes in binding strength of DNA oligonucleotide hybrids induced by cytosine modifications. These cytosine modifications, especially 5-methylcytosine but also its oxidized derivatives, have been increasingly studied in the context of epigenetics. Recently revealed correlations of epigenetic modifications and disease also render them interesting biomarkers for early diagnosis. Internal kinetic referencing allows us to probe and compare the influence of the different epigenetic cytosine modifications on the strengths of 7-nucleotide long DNA hybrids with one or two modified nucleotides by single-molecule imaging of their transient binding, revealing subtle differences in binding times. Interestingly, the influence of epigenetic modifications depends on their position in the DNA strand, and in the case of two modifications, effects are additive. The sensitivity of the assay indicates its potential for the direct detection of epigenetic disease markers.


Asunto(s)
Citosina , Microscopía , Citosina/química , Citosina/metabolismo , Epigénesis Genética , ADN/química , Metilación de ADN
19.
Nature ; 624(7991): 366-377, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38092913

RESUMEN

Cytosine DNA methylation is essential in brain development and is implicated in various neurological disorders. Understanding DNA methylation diversity across the entire brain in a spatial context is fundamental for a complete molecular atlas of brain cell types and their gene regulatory landscapes. Here we used single-nucleus methylome sequencing (snmC-seq3) and multi-omic sequencing (snm3C-seq)1 technologies to generate 301,626 methylomes and 176,003 chromatin conformation-methylome joint profiles from 117 dissected regions throughout the adult mouse brain. Using iterative clustering and integrating with companion whole-brain transcriptome and chromatin accessibility datasets, we constructed a methylation-based cell taxonomy with 4,673 cell groups and 274 cross-modality-annotated subclasses. We identified 2.6 million differentially methylated regions across the genome that represent potential gene regulation elements. Notably, we observed spatial cytosine methylation patterns on both genes and regulatory elements in cell types within and across brain regions. Brain-wide spatial transcriptomics data validated the association of spatial epigenetic diversity with transcription and improved the anatomical mapping of our epigenetic datasets. Furthermore, chromatin conformation diversities occurred in important neuronal genes and were highly associated with DNA methylation and transcription changes. Brain-wide cell-type comparisons enabled the construction of regulatory networks that incorporate transcription factors, regulatory elements and their potential downstream gene targets. Finally, intragenic DNA methylation and chromatin conformation patterns predicted alternative gene isoform expression observed in a whole-brain SMART-seq2 dataset. Our study establishes a brain-wide, single-cell DNA methylome and 3D multi-omic atlas and provides a valuable resource for comprehending the cellular-spatial and regulatory genome diversity of the mouse brain.


Asunto(s)
Encéfalo , Metilación de ADN , Epigenoma , Multiómica , Análisis de la Célula Individual , Animales , Ratones , Encéfalo/citología , Encéfalo/metabolismo , Cromatina/química , Cromatina/genética , Cromatina/metabolismo , Citosina/metabolismo , Conjuntos de Datos como Asunto , Factores de Transcripción/metabolismo , Transcripción Genética
20.
Sci Rep ; 13(1): 21885, 2023 12 11.
Artículo en Inglés | MEDLINE | ID: mdl-38081880

RESUMEN

Post-transcriptional modifications of RNA play a key role in performing a variety of biological processes, such as stability and immune tolerance, RNA splicing, protein translation and RNA degradation. One of these RNA modifications is m5c which participates in various cellular functions like RNA structural stability and translation efficiency, got popularity among biologists. By applying biological experiments to detect RNA m5c methylation sites would require much more efforts, time and money. Most of the researchers are using pre-processed RNA sequences of 41 nucleotides where the methylated cytosine is in the center. Therefore, it is possible that some of the information around these motif may have lost. The conventional methods are unable to process the RNA sequence directly due to high dimensionality and thus need optimized techniques for better features extraction. To handle the above challenges the goal of this study is to employ an end-to-end, 1D CNN based model to classify and interpret m5c methylated data sites. Moreover, our aim is to analyze the sequence in its full length where the methylated cytosine may not be in the center. The evaluation of the proposed architecture showed a promising results by outperforming state-of-the-art techniques in terms of sensitivity and accuracy. Our model achieve 96.70% sensitivity and 96.21% accuracy for 41 nucleotides sequences while 96.10% accuracy for full length sequences.


Asunto(s)
Metilación de ARN , ARN , ARN/genética , ARN/metabolismo , Citosina/metabolismo , Nucleótidos/metabolismo
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