This study is reported by Dr. Qianwen Sun's group from Tsinghua University, Dr. Wei Li's group from Guangzhou Medical University, Dr. Hui Jiang's group from Peking University Third Hospital, and Wei Xu's group from Chinese Academy of Agricultural Sciences. They developed a novel technique, DNA End tailing and sequencing (DEtail-seq), for meiotic DNA double-strand break (DSB) profiling.
In eukaryotes, meiosis is a fundamental process required for sexual reproduction. During meiosis, meiotic recombination is initiated with programmed DSBs induced by Spo11, and results in the exchange of genetic material between homologous chromosomes, which is beneficial for genetic diversity. Therefore, precise mapping of meiotic DSBs is essential for understanding the mechanism of meiotic homologous recombination. Spo11-induced meiotic DSBs can be divided into three parts: upstream DNA ends, downstream DNA ends, and Spo11-bound oligos (Figure 1A). Both upstream and downstream DNA ends provide 3' overhang structures, which contain a free 3' ssDNA end (Figure 1A). There are some disadvantages of previously reported methods for meiotic DSB detection, such as low sensitivity, cumbersome operation, and low resolution. To address these problems, the authors developed the DEtail-seq technique (Figure 1B): using Adaptase, a highly efficient single-stranded DNA ligation system, the 3' end of the DNA break is directly ligated to the 1st adaptor, and then the final library is constructed through a series of steps. After sequencing and data analysis, the position of the 3' end of the DNA break was mapped. The detection of restriction endonuclease cleavage sites showed that the DEtail-seq technique had a very high resolution, at or near the single nucleotide resolution (Figure 1C).
Based on the DEtail-seq technique, the investigators profiled the meiotic DSBs in budding yeast (Figure 2A), mouse (Figure 2B), and human germ cells (Figure 2C), and identified novel features of meiotic DSBs. Analysis of the mouse data showed that the meiotic DSB signal at leptotene/zygotene stage was enriched around de novo H3K4me3 peaks at leptotene stage (Figure 2B). Analysis of the human data showed that the meiotic DSB signal was enriched in the CTCF+ enhancer regions (Figure 2C). The authors believe that the DEtail-seq technique provides a powerful tool for researching meiosis in various species.
This work was funded by grants from the National Natural Science Foundation of China and Central Public-interest Scientific Institution Basal Research Fund.
