Project description:m6A is a widespread RNA modification which plays important roles in the regulation of gene expression. Methods for the global detection of m6A rely on immunoprecipitation of methylated transcripts using m6A antibodies. However, these methods are costly and require large amounts of input RNA, making them prohibitive for many experiments. Here, we describe DART-seq, an antibody-free method for m6A detection which enables transcriptome-wide mapping of m6A residues using low amounts of input material. DART-seq can be used to obtain global m6A maps using as little as 10 nanograms of total RNA and at single-molecule resolution. This method offers several improvements over current techniques and will facilitate detection of m6A in limiting cell and tissue types.
Project description:Methylation-based liquid biopsies show promise in detecting cancer from circulating cell-free DNA, but current limitations impede clinical application. Most assays necessitate substantial DNA inputs, posing challenges. Underrepresented tumor DNA fragments may go undetected during exponential amplification steps of traditional sequencing methods. Here we report LABS (Linear Amplification based Bisulfite Sequencing), enabling linear amplification of bisulfite-treated DNA fragments in a genome-wide, unbiased fashion, detecting cancer abnormalities with sub-nanogram inputs. Applying LABS to 100 patient samples revealed cancer-specific patterns, copy number alterations, and enhanced cancer detection accuracy by identifying tissue-of-origin and immune cell composition.
Project description:Pseudouridine (Ψ) is the most abundant post-transcriptional RNA modification. Various methods have been developed to achieve locus-specific Ψ detection; however, the existing methods often involve radiolabeling of RNA, require advanced experimental skills and can be time-consuming. Herein we report a radiolabeling-free,qPCR-based method to detect locus-specific Ψs in rRNA and mRNA. This method is based on Ψ chemical adduct (Ψ-CMC) induced mutation/deletion during reverse transcription (RT), leading to qPCR products of different melting temperatures. Utilizing high-throughput sequencing, we demonstrate that such misincorporation is a general feature of Ψ-CMC adduct during our improved RT conditions. We validated this method on known Ψ sites in rRNA and showed that the melting curves correlate with the modification level. Moreover, we successfully detected Ψs in mRNA and lncRNA of different abundance, and identified Ψ synthase that targets mRNA. Our facile method takes only 1.5 days to complete, and with slight adjustment it can be applied to detect other epitranscriptomic marks in the transcriptome.
Project description:The detection of hypermethylation markers on cell-free DNA (cfDNA) in biological fluids is a promising and non-invasive approach for early diagnosis and monitoring of human diseases. However, it is challenging to detect hypermethylation markers in a high-throughput, sensitive, and cost-effective manner. Here we presented a multiplex 5-methylcytosine marker barcode counting (MMBC-seq) technique and reported its clinical application for cfDNA from peripheral plasma samples. We identified an MMBC cancer detection panel and developed a scoring system to differentiate cancer versus healthy controls. In a multiple-cancer case-control study, the panel achieved a sensitivity and specificity of 80.2% and 95.7% respectively (AUC 0.906, 95% CI 0.846-0.948). The results suggest that MMBC-seq has great potential to realize non-invasive, flexible and clinically applicable cancer detection.
Project description:We used a highly sensitive nano-5hmC-Seal method and profiled the genome-wide distribution of 5-hydroxymethylcytosine (5hmC) in plasma cell-free DNA (cfDNA) from 384 patients with bladder, breast, colorectal, kidney, lung, or prostate cancer and 221 controls. We used machine learning and developed plasma cfDNA 5hmC signatures that are highly sensitive for cancer detection and cancer origin determination. We also identified genes and signaling pathways with aberrant DNA hydroxymethylation in six cancers.