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Development of a global DNA methylation bio-sensing system for cancer diagnostics

Wataru YOSHIDA

Senior Assistant Professor Wataru Yoshida and Professor Isao Karube et al. from the School of Bioscience and Biotechnology and the Graduate School of Bionics developed a bio-sensing system for global DNA methylation levels that can be applied to cancer diagnostics. The paper has been published in Analytica Chimica Acta (Vol. 990, p. 168-173, 2017)1.

DNA methylation of cytosine in CpG dinucleotides has important biological roles in regulation of gene expression. In cancer cells, hypomethylation has been reported in transposable elements, which constitute approximately 45% of the human genome; therefore, global DNA methylation levels are potential biomarkers for cancer diagnostics. The research group previously developed a bio-sensing system for detecting methylated CpG content in genomic DNA based on bioluminescence resonance energy transfer (BRET) using methyl-CpG-binding domain (MBD)-fused luciferase (MBD-luciferase)2. In the system, BRET between the artificial protein and DNA intercalating dye is detected on the methylated CpG site on genomic DNA; thus, methylated CpG content can be detected by the BRET signal (Fig. 1 left). However, a calibration curve was required to quantify global DNA methylation levels since the system does not detect unmethylated CpG content.


Fig. 1 A bio-sensing system for global DNA methylation levels using CXXC- and MBD-fused luciferase.

They then constructed a new unmethyl-CpG-binding domain (MLL CXXC)-fused luciferase (CXXC-luciferase) and developed a bio-sensing system for detecting unmethylated CpG content on genomic DNA on the same platform (Fig. 1 right). They demonstrated that global DNA methylation levels can be quantified by measuring BRET signals from CXXC-luciferase and MBD-luciferase without a calibration curve. In the future, the bio-sensing system could be applied for home cancer tests.

1. Yoshida W., Baba Y., Banzawa K., Karube I. A quantitative homogeneous assay for global DNA methylation levels using CpG-binding domain- and methyl-CpG-binding domain-fused luciferase. Anal. Chim. Acta (2017) 990, 168-173
http://www.sciencedirect.com/science/article/pii/S0003267017308504?via%3Dihub

2. Yoshida W., Baba Y., Karube I. Global DNA Methylation Detection System Using MBD-Fused Luciferase Based on Bioluminescence Resonance Energy Transfer Assay. Anal. Chem. (2016) 88, 9264-9268
http://pubs.acs.org/doi/abs/10.1021/acs.analchem.6b02565

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