scholarly journals The C. elegans RSA Complex Localizes Protein Phosphatase 2A to Centrosomes and Regulates Mitotic Spindle Assembly

Cell ◽  
2007 ◽  
Vol 128 (1) ◽  
pp. 115-127 ◽  
Author(s):  
Anne-Lore Schlaitz ◽  
Martin Srayko ◽  
Alexander Dammermann ◽  
Sophie Quintin ◽  
Natalie Wielsch ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Spindle Assembly ◽  
C Elegans ◽  
Phosphatase 2A ◽  
Mitotic Spindle Assembly

scholarly journals Centrosome Maturation and Mitotic Spindle Assembly in C. elegans Require SPD-5, a Protein with Multiple Coiled-Coil Domains

2002 ◽  
Vol 3 (5) ◽  
pp. 673-684 ◽  
Author(s):  
Danielle R. Hamill ◽  
Aaron F. Severson ◽  
J.Clayton Carter ◽  
Bruce Bowerman
Keyword(s):  
Mitotic Spindle ◽  
Coiled Coil ◽  
Spindle Assembly ◽  
C Elegans ◽  
Mitotic Spindle Assembly

scholarly journals Multiple pools of Protein Phosphatase 2A-B56 function to antagonize spindle assembly, promote kinetochore attachments and maintain cohesion in Drosophila Oocytes

2020 ◽  
Author(s):  
Janet K. Jang ◽  
Amy C. Gladstein ◽  
Arunika Das ◽  
Zachary L. Sisco ◽  
Kim S. McKim
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Spindle Assembly ◽  
Meiotic Spindle ◽  
Aurora B ◽  
Microtubule Organizing Center ◽  
Chromosomal Passenger ◽  
Organizing Center ◽  
Phosphatase 2A ◽  
Meiosis I

AbstractMeiosis in female oocytes lack centrosomes, the major microtubule-organizing center, which makes them especially vulnerable to aneuploidy. In the acentrosomal oocytes of Drosophila, meiotic spindle assembly depends on the chromosomal passenger complex (CPC). Aurora B is the catalytic component of the CPC while the remaining subunits regulate its localization. Using an inhibitor of Aurora B activity, Binucleine 2, we found that continuous Aurora B activity is required to maintain the oocyte spindle during meiosis I, and this activity is antagonized by phosphatases acting on spindle associated proteins such as kinesins. Protein Phosphatase 2A (PP2A) exists in two varieties, B55 and B56. While both antagonize Aurora B, B55 has only minor roles in meiosis I spindle function. The B56 subunit is encoded by two partially redundant paralogs in the Drosophila genome, wdb and wrd. Knocking down both paralogs showed that the B56 subunit is critical for maintaining sister chromatid cohesion, establishing end-on microtubule attachments, and the metaphase I arrest in oocytes. We found that WDB recruitment to the centromeres depends on BUBR1, MEI-S332, and kinetochore protein SPC105R. While BUBR1 has been shown previously to stabilize microtubule attachments in Drosophila oocytes, only SPC105R is required for cohesion maintenance during meiosis I. We propose that SPC105R promotes cohesion maintenance by recruiting two proteins that recruit PP2A, MEI-S332, and the Soronin homolog Dalmatian.

scholarly journals Localized accumulation of tubulin during semi-open mitosis in the Caenorhabditis elegans embryo

2012 ◽  
Vol 23 (9) ◽  
pp. 1688-1699 ◽  
Author(s):  
Hanako Hayashi ◽  
Kenji Kimura ◽  
Akatsuki Kimura
Keyword(s):  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Mitotic Spindle ◽  
Fluorescence Recovery After Photobleaching ◽  
Spindle Assembly ◽  
Small Gtpase ◽  
Microtubule Assembly ◽  
C Elegans ◽  
Nuclear Envelope Breakdown ◽  
Mitotic Spindle Assembly

The assembly of microtubules inside the cell is controlled both spatially and temporally. During mitosis, microtubule assembly must be activated locally at the nascent spindle region for mitotic spindle assembly to occur efficiently. In this paper, we report that mitotic spindle components, such as free tubulin subunits, accumulated in the nascent spindle region, independent of spindle formation in the Caenorhabditis elegans embryo. This accumulation coincided with nuclear envelope permeabilization, suggesting that permeabilization might trigger the accumulation. When permeabilization was induced earlier by knockdown of lamin, tubulin also accumulated earlier. The boundaries of the region of accumulation coincided with the remnant nuclear envelope, which remains after nuclear envelope breakdown in cells that undergo semi-open mitosis, such as those of C. elegans. Ran, a small GTPase protein, was required for tubulin accumulation. Fluorescence recovery after photobleaching analysis revealed that the accumulation was accompanied by an increase in the immobile fraction of free tubulin inside the remnant nuclear envelope. We propose that this newly identified mechanism of accumulation of free tubulin—and probably of other molecules—at the nascent spindle region contributes to efficient assembly of the mitotic spindle in the C. elegans embryo.

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