Efficient Purification and LC-MS/MS-based Assay Development for Ten-Eleven Translocation-2 5-Methylcytosine Dioxygenase

Research progress of human key DNA and RNA methylation-related enzymes assay

Gene methylation-related enzymes (GMREs) are disfunction and aberrantly expressed in a variety of cancers, such as lung, gastric, and pancreatic cancers and have important implications for human health. Therefore，it is critical for early diagnosis and therapy of tumor to develop strategies that allow rapid and sensitive quantitative and qualitative detection of GMREs. With the development of modern analytical techniques and the application of various biosensors, there are numerous methods have been developed for analysis of GMREs. Therefore, this paper provides a systematic review of the strategies for level and activity assay of various GMREs including methyltransferases and demethylase. The detection methods mainly involve immunohistochemistry, colorimetry, fluorescence, chemiluminescence, electrochemistry, etc. Then, this review also addresses the coordinated role of various detection probes, novel nanomaterials, and signal amplification methods. The aim is to highlight potential challenges in the present field, to expand the analytical application of GMREs detection strategies, and to meet the urgent need for future disease diagnosis and intervention.

Positive/negative ion-switching-based LC-MS/MS method for quantification of cytosine derivatives produced by the TET-family 5-methylcytosine dioxygenases

Cytosine methylation at carbon-5 (5mC) in DNA plays crucial roles in epigenetic transcriptional regulation during metazoan development. The iron (II), 2-oxoglutarate-dependent Ten-Eleven Translocation (TET)-family dioxygenases initiate active demethylation of 5mC. TET2 oxidizes 5mC in nucleic acids into 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine by iterative oxidation. Mutations in the TET2 gene are frequently detected in myeloid malignancies. Despite the established and emerging roles of TET oxygenases in health and diseases, in vitro characterization of these enzymes and their mutants is still in rudimentary stages. Here, we describe an improved positive/negative ion-switching-based liquid chromatography-tandem mass spectrometry (LC–MS/MS) method that can separate and quantify modified cytosine bases produced by TET-family 5-methylcytosine dioxygenases. This method will help in further elucidate the function of epigenetically important cytosine modifications. To the best of our knowledge, this is the first study reporting ion-switching-based LC–MS/MS method to analyse cytosine variants produced in TET catalysed reactions.