Publications by authors named "Eisuke Sumiyoshi"

6 Publications

  • Page 1 of 1

Tubulin isotype substitution revealed that isotype combination modulates microtubule dynamics in embryos.

J Cell Sci 2017 05 16;130(9):1652-1661. Epub 2017 Mar 16.

Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan

Microtubules (MTs) are polymers composed of α- and β-tubulin heterodimers that are generally encoded by genes at multiple loci. Despite implications of distinct properties depending on the isotype, how these heterodimers contribute to the diverse MT dynamics remains unclear. Here, by using genome editing and depletion of tubulin isotypes following RNAi, we demonstrate that four tubulin isotypes (hereafter referred to as α1, α2, β1 and β2) cooperatively confer distinct MT properties in early embryos GFP insertion into each isotype locus reveals their distinct expression levels and MT incorporation rates. Substitution of isotype coding regions demonstrates that, under the same isotype concentration, MTs composed of β1 have higher switching frequency between growth and shrinkage compared with MTs composed of β2. Lower concentration of β-tubulins results in slower growth rates, and the two α-tubulins distinctively affect growth rates of MTs composed of β1. Alteration of ratio and concentration of isotypes distinctively modulates both growth rate and switching frequency, and affects the amplitude of mitotic spindle oscillation. Collectively, our findings demonstrate that MT dynamics are modulated by the combination (ratio and concentration) of tubulin isotypes with distinct properties, which contributes to create diverse MT behaviors .
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http://dx.doi.org/10.1242/jcs.200923DOI Listing
May 2017

Caenorhabditis elegans Aurora A kinase is required for the formation of spindle microtubules in female meiosis.

Mol Biol Cell 2015 Nov 16;26(23):4187-96. Epub 2015 Sep 16.

Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan

In many animals, female meiotic spindles are assembled in the absence of centrosomes, the major microtubule (MT)-organizing centers. How MTs are formed and organized into meiotic spindles is poorly understood. Here we report that, in Caenorhabditis elegans, Aurora A kinase/AIR-1 is required for the formation of spindle microtubules during female meiosis. When AIR-1 was depleted or its kinase activity was inhibited in C. elegans oocytes, although MTs were formed around chromosomes at germinal vesicle breakdown (GVBD), they were decreased during meiotic prometaphase and failed to form a bipolar spindle, and chromosomes were not separated into two masses. Whereas AIR-1 protein was detected on and around meiotic spindles, its kinase-active form was concentrated on chromosomes at prometaphase and on interchromosomal MTs during late anaphase and telophase. We also found that AIR-1 is involved in the assembly of short, dynamic MTs in the meiotic cytoplasm, and these short MTs were actively incorporated into meiotic spindles. Collectively our results suggest that, after GVBD, the kinase activity of AIR-1 is continuously required for the assembly and/or stabilization of female meiotic spindle MTs.
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http://dx.doi.org/10.1091/mbc.E15-05-0258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4642853PMC
November 2015

Cell polarity: centrosomes release signals for polarization.

Curr Biol 2012 Apr;22(8):R281-3

Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.

New findings reveal that, in Caenorhabditis elegans embryos, the centrosome provides signals that induce cell polarization, independently of its function as the microtubule-organizing center.
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http://dx.doi.org/10.1016/j.cub.2012.03.009DOI Listing
April 2012

The β-catenin HMP-2 functions downstream of Src in parallel with the Wnt pathway in early embryogenesis of C. elegans.

Dev Biol 2011 Jul 6;355(2):302-12. Epub 2011 May 6.

Genome Biology Laboratory, National Institute of Genetics, 1111 Yata, Mishima, 411-8540, Japan.

The Wnt and Src pathways are widely used signal transduction pathways in development. β-catenin is utilized in both pathways, as a signal transducer and a component of the cadherin cell adhesion complex, respectively. A C. elegans β-catenin HMP-2 is involved in cell adhesion, but its signaling role has been unknown. Here, we report that in early embryogenesis HMP-2 acts as a signaling molecule in the Src signal. During early embryogenesis in C. elegans, the Wnt and Src pathways are redundantly involved in endoderm induction at the four-cell stage and spindle orientation in an ABar blastomere. RNAi experiments demonstrated that HMP-2 functions in the Src pathway, but in parallel with the Wnt pathway in these processes. HMP-2 localized at the cell boundaries and nuclei, and its localization at cell boundaries was negatively regulated by SRC-1. In addition, HMP-2 was Tyr-phosphorylated in a SRC-1-dependent manner in vivo. Taken together, we propose that HMP-2 functions downstream of the Src signaling pathway and contribute to endoderm induction and ABar spindle orientation, in parallel with the Wnt signaling pathway.
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http://dx.doi.org/10.1016/j.ydbio.2011.04.034DOI Listing
July 2011

C. elegans CPB-3 interacts with DAZ-1 and functions in multiple steps of germline development.

Dev Biol 2006 Jul 7;295(2):689-99. Epub 2006 Apr 7.

Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.

Cytoplasmic polyadenylation element-binding proteins (CPEBs) are well-conserved RNA-binding proteins, which regulate mRNA translation mainly through control of poly(A) elongation. Here, we show that CPB-3, one of the four CPEB homologs in C. elegans, positively regulates multiple aspects of oocyte production. CPB-3 protein was highly expressed in early meiotic regions of the hermaphrodite gonad. Worms deficient in cpb-3 were apparently impaired in germ cell proliferation and differentiation including sperm/oocyte switching and progression of female meiosis. We also show that cpb-3 is likely to promote the meiotic entry in parallel with gld-3, a component of one of the redundant but essential genetic pathways for the entry to and progression through meiosis. Taken together, CPEB appears to have a conserved role in the early phase of meiosis and in the sperm/oocyte specification, in addition to its reported function during meiotic progression.
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http://dx.doi.org/10.1016/j.ydbio.2006.04.002DOI Listing
July 2006

Protein phosphatase 4 is required for centrosome maturation in mitosis and sperm meiosis in C. elegans.

J Cell Sci 2002 Apr;115(Pt 7):1403-10

Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan.

The centrosome consists of two centrioles surrounded by the pericentriolar material (PCM). In late G2 phase, centrosomes enlarge by recruiting extra PCM, and concomitantly its microtubule nucleation activity increases dramatically. The regulatory mechanisms of this dynamic change of centrosomes are not well understood. Protein phosphatase 4 (PP4) is known to localize to mitotic centrosomes in mammals and Drosophila. An involvement of PP4 in the mitotic spindle assembly has been implicated in Drosophila, but in vivo functions of PP4 in other organisms are largely unknown. Here we characterize two Caenorhabditis elegans PP4 genes, named pph-4.1 and pph-4.2. Inhibition of the function of each gene by RNA-mediated interference (RNAi) revealed that PPH-4.1 was essential for embryogenesis but PPH-4.2 was not. More specifically, PPH-4.1 was required for the formation of spindles in mitosis and sperm meiosis. However, this phosphatase was apparently dispensable for female meiotic divisions, which do not depend on centrosomes. In the cell depleted of pph-4.1 activity, localization of gamma-tubulin and a Polo-like kinase homologue to the centrosome was severely disturbed. Immunofluorescence staining revealed that PPH-4.1 was present at centrosomes from prophase to telophase, but not during interphase. These results indicate that PPH-4.1 is a centrosomal protein involved in the recruitment of PCM components to the centrosome, and is essential for the activation of microtubule nucleation potential of the centrosome. Furthermore, chiasmata between homologous chromosomes were often absent in oocytes that lacked pph-4.1 activity. Thus, besides promoting spindle formation, PPH-4.1 appears to play a role in either the establishment or the maintenance of chiasmata during meiotic prophase I.
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April 2002
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