||Matsuda S, Yasukawa T*, Sakaguchi S, Ichiyanagi K, Unoki M, Gotoh K, Fukuda K, Sasaki H, Suzuki T, Kang D., Accurate estimation of 5-methylcytosine in mammalian mitochondrial DNA, Sci. Rep., 8, 5801, [*corresponding author], 2018.04.
||Moss, C.F., Dalla Rosa, I., Hunt, L.E., Yasukawa, T., Young, R., Jones, A.W.E., Reddy, K., Desai, R., Virtue, S., Elgar, G., Voshol, P., Taylor, M.S., Holt I.J., Reijns, M.A.M., Spinazzola, A., Aberrant ribonucleotide incorporation and multiple deletions in mitochondrial DNA of the murine MPV17 disease model, Nucleic Acids Res., 45, 22, 12808-12815, 2017.11, All DNA polymerases misincorporate ribonucleotides
despite their preference for deoxyribonucleotides,
and analysis of cultured cells indicates
that mammalian mitochondrial DNA (mtDNA) tolerates
such replication errors. However, it is not clear
to what extent misincorporation occurs in tissues,
or whether this plays a role in human disease.
Here, we show that mtDNA of solid tissues contains
many more embedded ribonucleotides than that
of cultured cells, consistent with the high ratio of
ribonucleotide to deoxynucleotide triphosphates
in tissues, and that riboadenosines account for
three-quarters of them. The pattern of embedded
ribonucleotides changes in a mouse model of Mpv17
deficiency, which displays a marked increase in
rGMPs in mtDNA. However, while the mitochondrial
dGTP is low in the Mpv17?/? liver, the brain shows
no change in the overall dGTP pool, leading us
to suggest that Mpv17 determines the local concentration
or quality of dGTP. Embedded rGMPs
are expected to distort the mtDNA and impede its
replication, and elevated rGMP incorporation is
associated with early-onset mtDNA depletion in
liver and late-onset multiple deletions in brain of
Mpv17?/? mice. These findings suggest aberrant
ribonucleotide incorporation is a primary mtDNA
abnormality that can result in pathology..
||Akman, G., Desai, R., Bailey, L.J., Yasukawa, T., Dalla Rosa, I., Durigon, R., Holmes, J.B., Moss, C.F., Mennuni, M., Houlden, H., Crouch, R.J., Hanna, M.G., Pitceathly, R.D., Spinazzola, A., Holt I.J., Pathological ribonuclease H1 causes R-loop depletion and aberrant DNA segregation in mitochondria, Proc. Natl. Acad. Sci. USA., 113, 30, E4276-E4285, 2016.07, The genetic information in mammalian mitochondrial DNA is denselypacked; there are no introns and only one sizeable noncoding, orcontrol, region containing key cis-elements for its replication andexpression. Many molecules of mitochondrial DNA bear a thirdstrand of DNA, known as “7S DNA,” which forms a displacement(D-) loop in the control region. Here we show that many other moleculescontain RNA as a third strand. The RNA of these R-loops mapsto the control region of the mitochondrial DNA and is complementaryto 7S DNA. Ribonuclease H1 is essential for mitochondrial DNAreplication; it degrades RNA hybridized to DNA, so the R-loop is apotential substrate. In cells with a pathological variant of ribonucleaseH1 associated with mitochondrial disease, R-loops are of lowabundance, and there is mitochondrial DNA aggregation. These findingsimplicate ribonuclease H1 and RNA in the physical segregationof mitochondrial DNA, perturbation of which represents a previouslyunidentified disease mechanism..
||Qu, J., Yasukawa, T.*, Kang, D., Suppression of mitochondrial transcription initiation complexes changes the balance of replication intermediates of mitochondrial DNA and reduces 7S DNA in cultured human cells, J. Biochem., doi:10.1093/jb/mvw010, [*corresponding author], 2016.02, [2017年日本生化学会JB論文賞受賞].
||Reyes, A., Kazak, L., Wood, S.R., Yasukawa, T., Jacobs, H.T., Holt I.J., Mitochondrial DNA replication proceeds via a ‘bootlace’ mechanism involving the incorporation of processed transcripts, Nucleic Acids Res., 10.1093/nar/gkt196, 41(11):5837-5850, 2013.06.
||Ruhanen, H., Ushakov, K., Yasukawa, T.* [*corresponding author], Involvement of DNA ligase III and ribonuclease H1 in mitochondrial DNA replication in cultured human cells, Biochim. Biophys. Acta, 1813, 2000-2007, 2011.12.
||Ruhanen, H., Borrie, S., Szabadkai, G., Tyynismaa, H., Jones, A. W. E., Kang, D., Taanman, J.-W., Yasukawa, T.* [*corresponding author], Mitochondrial single-stranded DNA binding protein is required for maintenance of mitochondrial DNA and 7S DNA but is not required for mitochondrial nucleoid organization, Biochim. Biophys. Acta, 1803, 931-939, 2010.08.
||Yasukawa, T., Reyes, A., Cluett, T. J., Yang, M. Y., Bowmaker, M., Jacobs, H. T., Holt, I. J., Replication of vertebrate mitochondrial DNA entails transient ribonucleotide incorporation throughout the lagging strand, EMBO J., 25, 5358-5371, 2006.10.
||Yasukawa, T., Yang, M. Y., Jacobs, H. T., Holt, I. J., A bidirectional origin of replication maps to the major noncoding region of human mitochondrial DNA, Mol. Cell, 18, 651-662, 2005.06.
||Yasukawa, T., Suzuki, T., Ishii, N., Ohta, S., Watanabe, K., Wobble modification defect in tRNA disturbs codon-anticodon interaction in a mitochondrial disease, EMBO J., 20, 4794-4802, 2001.09.