DNA methylation plays an essential role in mammalian development[1].However,how DNA methylation is inherited between generations and if there is family-specific DNA methylation pattern remains to be elucidated[2].In this study,we collect male blood samples including a big pedigree of the descendants of an ancient Chinese empire and samples from different haplogroups to study their whole genome DNA methylation pattern.We find 115 male family-specific methylation sites from three families.The difference of whole genome DNA methylation pattern correlates
Detection of circulating tumor DNAs(ct DNAs) in cancer patients is an important component of cancer precision medicine ct DNAs. Compared to the traditional physical and biochemical methods, blood-based ct DNA detection offers a non-invasive and easily accessible way for cancer diagnosis, prognostic determination, and guidance for treatment. While studies on this topic are currently underway, clinical translation of ct DNA detection in various types of cancers has been attracting much attention, due to the great potential of ct DNA as blood-based biomarkers for early diagnosis and treatment of cancers. ct DNAs are detected and tracked primarily based on tumorrelated genetic and epigenetic alterations. In this article, we reviewed the available studies on ct DNA detection and described the representative methods. We also discussed the current understanding of ct DNAs in cancer patients and their availability as potential biomarkers for clinical purposes. Considering the progress made and challenges involved in accurate detection of specific cell-free nucleic acids, ct DNAs hold promise to serve as biomarkers for cancer patients, and further validation is needed prior to their broad clinical use.
Detecting cell-free DNA(cfDNA) or circulating tumor DNA(ctDNA) in plasma or serum could serve as a "liquid biopsy", which would be useful for numerous diagnostic applications. cfDNA methylation detection is one of the most promising approaches for cancer risk assessment. Here, we reviewed the literature related to the use of serum or plasma circulating cell-free DNA for cancer diagnosis in the early stage and their power as future biomarkers.
Background:Induced pluripotent stem cells(iPSCs)and embryonic stem cells(ESCs)share many common features,including similar morphology,gene expression and in vitro differentiation profiles.However,genomic stability is much lower in iPSCs than in ESCs.In the current study,we examined whether changes in DNA damage repair in iPSCs are responsible for their greater tendency towards mutagenesis.Methods:Mouse iPSCs,ESCs and embryonic fibroblasts were exposed to ionizing radiation(4 Gy)to introduce dou-ble-strand DNA breaks.At 4 h later,fidelity of DNA damage repair was assessed using whole-genome re-sequencing.We also analyzed genomic stability in mice derived from iPSCs versus ESCs.Results:In comparison to ESCs and embryonic fibroblasts,iPSCs had lower DNA damage repair capacity,more somatic mutations and short indels after irradiation.iPSCs showed greater non-homologous end joining DNA repair and less homologous recombination DNA repair.Mice derived from iPSCs had lower DNA damage repair capacity than ESC-derived mice as well as C57 control mice.Conclusions:The relatively low genomic stability of iPSCs and their high rate of tumorigenesis in vivo appear to be due,at least in part,to low fidelity of DNA damage repair.
To prevent the damage caused by DNA strand breaks, eukaryotic cells have evolved a series of highly conserved DNA repair mechanisms. The ubiquitously expressed acetyltransferase, Tip60, plays a central role in ATM (ataxia-telangiectasia mutated) activation which is involved in DNA repair. Recent work uncovered a new mechanism of ATM activation mediated by Tip60 and demonstrated that histone methylation, specifically, trimethylation of histone H3, is a key factor in the process. Here, we review the current understanding of how Tip60 is activated and how it activates ATM in response to DNA damage.
