Karyokinesis

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Agneta Onfelt - One of the best experts on this subject based on the ideXlab platform.

Anna Renglin - One of the best experts on this subject based on the ideXlab platform.

Kazufumi Takamune - One of the best experts on this subject based on the ideXlab platform.

  • Xtr, a plural tudor domain-containing protein, is involved in the translational regulation of maternal mRNA during oocyte maturation in Xenopus laevis.
    Development Growth & Differentiation, 2012
    Co-Authors: Hiroki Ohgami, Golam Mostafa, Masateru Hiyoshi, Hideo Kubo, Kazufumi Takamune
    Abstract:

    Xtr in the fertilized eggs of Xenopus has been demonstrated to be a member of a messenger ribonucleoprotein (mRNP) complex that plays a crucial role in Karyokinesis during cleavage. Since the Xtr is also present both in oocytes and spermatocytes and its amount increases immediately after spematogenic cells enter into the meiotic phase, this protein was also predicted to act during meiotic progression. Taking advantage of Xenopus oocytes’ large size to microinject anti-Xtr antibody into them for inhibition of Xtr function, we examined the role of Xtr in meiotic progression of oocytes. Microinjection of anti-Xtr antibody into immature oocytes followed by reinitiation of oocyte maturation did not affect germinal vesicle break down and the oscillation of Cdc2/cyclin B activity during meiotic progression but caused abnormal spindle formation and chromosomal alignment at meiotic metaphase I and II. Immunoprecipitation of Xtr showed the association of Xtr with FRGY2 and mRNAs such as RCC1 and XL-INCENP mRNAs, which are involved in the progression of Karyokinesis. When anti-Xtr antibody was injected into oocytes, translation of XL-INCENP mRNA, which is known to be repressed in immature oocytes and induced after reinitiation of oocyte maturation, was inhibited even if the oocytes were treated with progesterone. A similar translational regulation was observed in oocytes injected with a reporter mRNA, which was composed of an enhanced green fluorescent protein open reading frame followed by the 3′ untranslational region (3′UTR) of XL-INCENP mRNA. These results indicate that Xtr regulates the translation of XL-INCENP mRNA through its 3′UTR during meiotic progression of oocyte.

  • 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
    Development Growth & Differentiation, 2009
    Co-Authors: Golam Mostafa, Tetsuharu Sugimoto, Masateru Hiyoshi, Hiroshi Kawasaki, Hideo Kubo, Ken Matsumoto, Kazufumi Takamune
    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.

  • involvement of xtr xenopus tudor repeat in microtubule assembly around nucleus and Karyokinesis during cleavage in xenopus laevis
    Development Growth & Differentiation, 2005
    Co-Authors: Masateru Hiyoshi, Nobushige Nakajo, Kazufumi Takamune
    Abstract:

    We have previously shown that the transcriptional product of the novel gene, Xenopus tudor repeat (Xtr), occurred exclusively in germline cells and early embryonic cells and that the putative Xtr contained plural tudor domains which are thought to play a role in the protein–protein interactions. To understand the role of Xtr, we produced an antibody against a polypeptide containing Xtr tudor domains as an antigen and investigated the distribution and the function of the Xtr. Immunoprecipitation/Western blot and immunohistochemical analyses indicated a similar occurrence of the Xtr to the mRNA except for a slightly different profile of its amount during spermatogenesis. In spite of a large amount of Xtr mRNA at late-secondary spermatogonial stage, the amount of Xtr was kept at a low level until this stage and increased after entering into the meiotic phase. Depletion of the Xtr function in the activated eggs by injection of the anti-Xtr antibody caused the inhibition both of microtubule assembly around nucleus and of Karyokinesis progression after prophase, but not of the oscillation of H1 kinase activity. These results suggest that the Karyokinesis of at least early embryonic cells are regulated by unique mechanisms in which the Xtr is involved.

John E Eriksson - One of the best experts on this subject based on the ideXlab platform.

Annsofi Harmalabrasken - One of the best experts on this subject based on the ideXlab platform.

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