Project description:The effects of DNASE1L3 or DNASE1 deficiency on cfDNA methylation was explored in plasma of mice deficient in these nucleases and in DNASE1L3-deficient humans. Compared to wildtype cfDNA, cfDNA in Dnase1l3-deficient mice was significantly hypomethylated, while cfDNA in Dnase1-deficient mice was hypermethylated. The cfDNA hypomethylation in Dnase1l3-deficient mice was due to increased fragmentation and representation from open chromatin regions (OCRs) and CpG islands (CGIs). These findings were absent in Dnase1-deficient mice.
Project description:The effects of DNASE1L3 or DNASE1 deficiency on cfDNA methylation was explored in plasma of mice deficient in these nucleases and in DNASE1L3-deficient humans. Compared to wildtype cfDNA, cfDNA in Dnase1l3-deficient mice was significantly hypomethylated, while cfDNA in Dnase1-deficient mice was hypermethylated. The cfDNA hypomethylation in Dnase1l3-deficient mice was due to increased fragmentation and representation from open chromatin regions (OCRs) and CpG islands (CGIs). These findings were absent in Dnase1-deficient mice.
Project description:T-cell independent type II (TI-II) antigens, such as capsular polysaccharides, have multivalent epitope, which induce B cell activation, plasma cell differentiation and antibody production by strongly cross-linking B cell receptors. However, the mechanism of B cell activation by TI-II antigens remains unclear. In this study, we demonstrate that DNA endonuclease DNase1L3 (also termed DNase g) is required for the TI-II response. The production of antigen-specific antibodies was severely diminished in DNase1L3-deficient mice upon immunization with TI-II antigens, but not with TD antigens. Bone-marrow chimeric mice and B cell transfer experiments revealed that B-cell-intrinsic DNase1L3 was required for the TI-II response. DNase1L3-deficient B cells were defective in cell proliferation and plasma cell differentiation in the TI-II response in vivo as well as in vitro, which was not rescued by co-culture with DNase1L3-sufficient B cells in vitro, disproving an involvement of a secretory DNase1L3. In vitro stimulation with TI-II antigen transiently increased expression of DNase1L3 and its translocation into the nucleus. RNA-seq analysis of ex-vivo B cells having been responded to TI-II antigen in vivo revealed a marked reduction of Myc-target gene sets in DNase1L3-deficient B cells. Expression of IRF4, the gene of which is a target of Myc, was diminished in the ex-vivo DNase1L3-deficient B cells, in which forced expression of IRF4 restored the TI-II response in vivo. These data revealed an unexpected role of DNase1L3 in a missing link between B cell receptor signaling and B cell activation in the TI-II response, giving a valuable clue to molecularly dissect this response.
Project description:The dataset contains sequencing data in wildtype, Dnase1-deficient and Dnase1l3-deficient mice. We performed 2 x 75bp paired-end whole genome bisulfite sequencing of pooled plasma cell-free DNA (cfDNA) and buffy coat genomic DNA. The effects of DNASE1L3 or DNASE1 deficiency on cfDNA methylation was explored in plasma of mice deficient in these nucleases.
Project description:Background: Cell free DNA (cfDNA) in plasma has received increasing attention and has been studied in a broad range of clinical conditions implicating inflammation, cancer, and aging. However, few studies have focused on mitochondrial DNA (mtDNA) in the cell free form. This study characterized the size distribution and sequence characteristics of plasma cell free mtDNA (cf mtDNA) in humans.Methods and Results: We optimized DNA isolation and next-generation sequencing library preparation protocols to better retain short DNA fragments from plasma, and applied these optimized methods to plasma samples from patients with sepsis. After massive parallel sequencing, we verified that our methods can retain substantially shorter DNA fragments than the standard isolation method, resulting in an average of 11.5 fold increase in short DNA fragments yield (DNA < 100bp). We report that cf mtDNA in plasma is highly enriched in short-size cfDNA (30 ~ 60 bp), which is much shorter than the value previously reported (~140 bp). Motivated by this unique size distribution, we size-selected short cfDNA fragments from the sequencing library, which further increased the mtDNA recovery rate by an average of 10.4 fold. Using this approach we detected mixtures of different mtDNA sequences, termed heteroplasmy, in plasma from 3 patients. In one patient who previously received bone marrow transplantation, different minor allele frequencies were observed between plasma and white blood cells (WBC) at heteroplasmic mtDNA sites, consistent with mixed-tissue origin for plasma DNA.Conclusion: mtDNA in plasma exists as very short fragments that exhibit mtDNA heteroplasmy distribution differences from that found in a single organ/tissue. This study is the first report of genome wide identification of mtDNA heteroplasmy in human plasma. Our optimized method can be used to investigate the potential utility of cf mtDNA fragments and heteroplasmy as biomarkers in various diseases.
Project description:We intend to establish an efficient method for plasma cfDNA extraction and Bisulfite transformation to facilitate the detection of DNA methylation status using multiplex fluorescence PCR. Meanwhile, we expect to identify several plasma methylation markers that can be highly sensitive for multi-cancer detection. Finally, we will provide a pan-cancer blood test that is easy to operate, low cost, accurate and easy to promote.