Biology subjects

Gilat, N.

Publications and source records attributed to Gilat, N..

3 recordsLinked to original sources

bioRxiv2022

Simultaneous global labeling (SiGL) of 5-methylcytosine and 5-hydroxymethylcytosine by DNA alkylation with a synthetic cofactor and engineered methyltransferase

5-methylcytosine and 5-hydroxymethylcytosine are epigenetic modifications involved in gene regulation and cancer. Here, we describe a new, simple, and high-throughput platform for multi-colour epigenetic analysis. The novelty of our approach is the ability to multiplex methylation and de-methylation signals in the same assay. We utilize an engineered methyltransferase enzyme that recognizes and labels all unmodified CpG sites with a fluorescent cofactor. In combination with the already established labelling of the de-methylation mark 5-hydroxymethylcytosine via enzymatic glycosylation, we obtained a robust platform for simultaneous epigenetic analysis of these marks. We assessed the global epigenetic levels in multiple samples of colorectal cancer and observed a reduction in 5-hydroxymethylcytosine levels, but no change in DNA methylation levels between sick and healthy individuals. We also measured epigenetic modifications in chronic lymphocytic leukaemia and observed a decrease in both modification levels. Our results indicate that this assay may be used for the epigenetic characterization of clinical samples for research and patient management.

genetics↗

bioRxiv2021

Genome wide mapping of DNA lesions by Repair Assisted Damage Detection sequencing - RADD-Seq

Mapping DNA damage and its repair has immense potential in understanding environmental exposures, their genotoxicity, and their impact on human health. Monitoring changes in genomic stability also aids in the diagnosis of numerous DNA-related diseases, like cancer, and assists in monitoring their progression and prognosis. However, genome-wide maps of DNA damage distribution are challenging to produce. Here we describe the localization of DNA damage and repair loci by Repair Assisted Damage Detection sequencing - RADD-Seq. Based on the enrichment of damage lesions coupled with a pull-down assay and followed by next generation sequencing, this method is easy to perform and can produce compelling results with minimal coverage. RADD-seq enables the localization of both DNA damage and repair sites for a wide range of single-strand damage types. Using this technique, we created a genome-wide map of oxidative DNA damage loci before and after repair. Oxidative lesions were heterogeneously distributed along the human genome, with less damage occurring in tight chromatin regions. Furthermore, we showed repair is prioritized for highly expressed, essential genes and in open chromatin regions. RADD-seq sheds light on cellular repair mechanisms and capable of identifying genomic hotspots prone to mutation.

genomics↗

bioRxiv2019

Global Modulation in DNA Epigenetics during Pro-Inflammatory Macrophage Activation

DNA methylation patterns create distinct gene expression profiles. These patterns are maintained after cell division, thus enabling the differentiation and maintenance of multiple cell types from the same genome sequence. The advantage of this mechanism for transcriptional control is that chemical-encoding allows to rapidly establish new epigenetic patterns \"on-demand\" through enzymatic methylation and de-methylation of DNA. Here we show that this feature is associated with the fast response of macrophages during their pro-inflammatory activation. By using a combination of mass spectroscopy and single-molecule imaging to quantify global epigenetic changes in the genomes of primary macrophages, we followed three distinct DNA marks (methylated, hydroxymethylated and unmethylated), involved in establishing new DNA methylation patterns during pro-inflammatory activation. The observed epigenetic modulation together with gene expression data generated for the involved enzymatic machinery, may suggest that de-methylation upon LPS-activation starts with oxidation of methylated CpGs, followed by excision-repair of these oxidized bases and their replacement with unmodified cytosine.

immunology↗