Kazufumi Mochizuki

Picture of the Group Leader Kazufumi Mochizuki

Small RNA-directed DNA elimination in Tetrahymena

  • Transposable elements are molecular parasites that are able to move from one genome position to another. Cells in our body have a mechanism to silence these potentially harmful elements: locking transposable element into a closed form chromatin, called heterochromatin. Chemically, both transposable elements and the other parts of the genome are just stretches of DNA. So, how can cells distinguish junk from precious DNA? Evidence suggests that small RNAs, ~20-30 nucleotides in length, act as security guards to identify transposable elements. However, many remains unknown about how these small RNAs are produced, how they patrol the genome, and how they induce heterochromatin. Our group studies how short RNAs lock transposable elements into heterochromatin using the tiny-hairy protozoan Tetrahymena as a model. Moreover, Tetrahymena is able to eliminate heterochromatinized transposable elements from the genome. We are trying to understand how this special ability has been evolved.

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    Kazufumi Mochizuki
    Group Leader
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Selected Publications

Vogt, A., Mochizuki, K. (2013). A domesticated PiggyBac transposase interacts with heterochromatin and catalyzes reproducible DNA elimination in Tetrahymena. PLoS Genet. 9(12):e1004032 (abstract)
Schoeberl, UE., Kurth, HM., Noto, T., Mochizuki, K. (2012). Biased transcription and selective degradation of small RNAs shape the pattern of DNA elimination in Tetrahymena. Genes Dev. 26(15):1729-42 (abstract)
Noto, T., Kurth, HM., Kataoka, K., Aronica, L., DeSouza, LV., Siu, KW., Pearlman, RE., Gorovsky, MA., Mochizuki, K. (2010). The Tetrahymena argonaute-binding protein Giw1p directs a mature argonaute-siRNA complex to the nucleus. Cell. 140(5):692-703 (abstract)
Kurth, HM., Mochizuki, K. (2009). 2'-O-methylation stabilizes Piwi-associated small RNAs and ensures DNA elimination in Tetrahymena. RNA. 15(4):675-85 (abstract)
Aronica, L., Bednenko, J., Noto, T., DeSouza, LV., Siu, KW., Loidl, J., Pearlman, RE., Gorovsky, MA., Mochizuki, K. (2008). Study of an RNA helicase implicates small RNA-noncoding RNA interactions in programmed DNA elimination in Tetrahymena. Genes Dev. 22(16):2228-41 (abstract)


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