Methods in molecular biology
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Aberrations of the DNA methylome contribute to onset and progression of diseases. Whole genome bisulfite sequencing (WGBS) is the only analytical method covering the complete methylome. ⋯ In tagmentation-based WGBS (TWGBS), several DNA and time-consuming steps of the conventional WGBS library preparation are circumvented by the use of a hyperactive transposase, which simultaneously fragments DNA and appends sequencing adapters. TWGBS requires only nanogram amounts of DNA and, thus, is well suited to study precious biological specimens such as sorted cells or micro-dissected tissue samples.
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Spinal muscular atrophy (SMA), the most common gentic cause of infantile death caused by mutations in the SMN1 gene, presents a unique case in the field of splice modulation therapy, where a gene (or lack of) is responsible for causing the disease phenotype but treatment is not focused around it. Antisense therapy targeting SMN2 which leads to SMN protein expression has been at the forefront of research when it comes to developing a feasible therapy for treating SMA. ⋯ This propelled the research community to investigate new chemistries of antisense oligonucleotides (ASOs) that may be better in both treatment and cost efficiency. Here we describe two types of ASOs, phosphorodiamidate morpholino oligomers (PMOs) and locked nucleic acids (LNA)-DNA mixmers, being investigated as potential treatments for SMA, and methods used to test their efficacy, including quantitative RT-PCR, Western blotting, and immunofluorescence staining to detect SMN in nuclear gems/Cajal bodies, in type I SMA patient fibroblast cell lines.
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Esophageal and esophagogastric adenocarcinoma is highly prevalent in the Western populations and is a major cause of cancer-related morbidity and mortality worldwide. The incidence of esophageal adenocarcinoma is rapidly rising in the Western populations. The major predisposing diseases and pathogenesis (gastro-esophageal reflux disease, Barrett esophagus, and dysplasia) of the cancer are well known. There is an urgent need for works of the multidisciplinary teams (clinical, pathological, the molecular biology and translational research) for improved outcomes of patients with this cancer.
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Antisense-mediated exon skipping and exon inclusion have proven to be powerful tools for treating neuromuscular diseases. The approval of Exondys 51 (eteplirsen) and Spinraza (nusinersen) for the treatment of patients with Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA) was the most noteworthy accomplishment in 2016. Exon skipping uses short DNA-like molecules called antisense oligonucleotides (AONs) to correct the disrupted reading frame, allowing the production of functional quasi-dystrophin proteins, and ameliorate the progression of the disease. ⋯ A major challenge in exon skipping and exon inclusion is the difficulty in designing effective AONs. The mechanism of mRNA splicing is highly complex, and the efficacy of AONs is often unpredictable. We will discuss the design of effective AONs for exon skipping and exon inclusion in this chapter.
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DNA cytosine methylation is one of the most abundant epigenetic marks found in the plant nuclear genome. Bisulfite sequencing (BS-Seq) is the method of choice for profiling DNA cytosine methylation genome-wide at a single nucleotide resolution. ⋯ By deep sequencing of the bisulfite converted genomic DNA, the methylation level of each mappable cytosine position in the genome could be measured. In this chapter, we present a detailed 2-day protocol for performing a BS-Seq experiment and a simple bioinformatic workflow for wet lab biologists to visualize the methylation data.