Xtr, a plural tudor domain-containing protein, coexists with FRGY2 both in cytoplasmic mRNP particle and germ plasm in Xenopus embryo: Its possible role in translational regulation of maternal mRNAs

Authors

  • Md. Golam Mostafa,

    1. Department of Life and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami
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  • Tetsuharu Sugimoto,

    1. Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555
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  • Masateru Hiyoshi,

    1. Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811
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  • Hiroshi Kawasaki,

    1. Supramolecular Biology, International Graduate School of Arts and Sciences, Yokohama City University, 1-7-29 Suehiro-cho, Yokohama 230-0045
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  • Hideo Kubo,

    1. Department of Medical Biology, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Tokyo 156-8506
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  • Ken Matsumoto,

    1. Laboratory of Cellular Biochemistry, RIKEN, 2-1 Hirosawa, Saitama 351-0198
    2. PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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  • Shin-Ichi Abe,

    1. Department of Life and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami
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  • Kazufumi Takamune

    Corresponding author
    1. Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555
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*Author to whom all correspondence should be addressed.
Email: takamune@gpo.kumamoto-u.ac.jp

Abstract

Xtr is present exclusively in early embryonic and germline cells. We have previously shown that loss-of-function of the Xtr in embryos causes arrest of karyokinesis progression. Since Xtr contains plural tudor domains, which are known to associate with target proteins directly, we examined Xtr-interacting proteins by immunoprecipitation with an anti-Xtr monoclonal antibody and detected a few RNA-binding proteins such as FRGY2, a component of messenger ribonucleoprotein (mRNP) particle. The coexistence of Xtr with FRGY2 by constituting an mRNP particle was further confirmed by gel filtration assay. Search of mRNAs in the immunoprecipitate with Xtr suggested that the Xtr-associated molecules included several mRNAs, of which translational products were known to play crucial roles in karyokinesis progression (RCC1, XRHAMM, and so on) and in germ cell development (XDead end). Immunohistochemical observation clearly showed the co-localization of Xtr with FRGY2 also in germ plasm, in which XDead end mRNA has been shown to be localized specifically. Taken together, we proposed the possible role of Xtr in translational activation of the maternal mRNAs repressed in mRNP particle.

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