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Centrosome/spindle pole-associated protein regulates cytokinesis via promoting the recruitment of MyoGEF to the central spindle.

ABSTRACT: Cooperative communications between the central spindle and the contractile ring are critical for the spatial and temporal regulation of cytokinesis. Here we report that MyoGEF, a guanine nucleotide exchange factor that localizes to the central spindle and cleavage furrow, interacts with centrosome/spindle pole-associated protein (CSPP), which is concentrated at the spindle pole and central spindle during mitosis and cytokinesis. Both in vitro and in vivo pulldown assays show that MyoGEF interacts with CSPP. The C-terminus of MyoGEF and N-terminus of CSPP are required for their interaction. Immunofluorescence analysis indicates that MyoGEF and CSPP colocalize at the central spindle. Depletion of CSPP or MyoGEF by RNA-interference (RNAi) not only causes defects in mitosis and cytokinesis, such as metaphase arrest and furrow regression, but also mislocalization of nonmuscle myosin II with a phosphorylated myosin regulatory light chain (p-MRLC). Importantly, CSPP depletion by RNAi interferes with MyoGEF localization at the central spindle. Finally, MyoGEF interacts with ECT2, and RNAi-mediated depletion of MyoGEF leads to mislocalization of ECT2 and RhoA during cytokinesis. Therefore, we propose that CSPP interacts with and recruits MyoGEF to the central spindle, where MyoGEF contributes to the spatiotemporal regulation of cytokinesis.

SUBMITTER: Asiedu M

PROVIDER: S-EPMC2649278 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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Centrosome/spindle pole-associated protein regulates cytokinesis via promoting the recruitment of MyoGEF to the central spindle.

Asiedu Michael M Wu Di D Matsumura Fumio F Wei Qize Q

Molecular biology of the cell 20090107 5

Cooperative communications between the central spindle and the contractile ring are critical for the spatial and temporal regulation of cytokinesis. Here we report that MyoGEF, a guanine nucleotide exchange factor that localizes to the central spindle and cleavage furrow, interacts with centrosome/spindle pole-associated protein (CSPP), which is concentrated at the spindle pole and central spindle during mitosis and cytokinesis. Both in vitro and in vivo pulldown assays show that MyoGEF interact ...[more]

PMID: 19129481

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Project description:BackgroundMaintenance of centrosome number in cells is essential for accurate distribution of chromosomes at mitosis and is dependent on both proper centrosome duplication during interphase and their accurate distribution to daughter cells at cytokinesis. Two essential regulators of cell cycle progression are protein phosphatase 1 (PP1) and Aurora A kinase (AURKA), and their activities are each regulated by the PP1 regulatory subunit, protein phosphatase 1 regulatory subunit 2 (PPP1R2). We observed an increase in centrosome number after overexpression of these proteins in cells. Each of these proteins is found on the midbody in telophase and overexpression of PPP1R2 and its mutants increased cell ploidy and disrupted cytokinesis. This suggests that the increase in centrosome number we observed in PPP1R2 overexpressing cells was a consequence of errors in cell division. Furthermore, overexpression of PPP1R2 and its mutants increased midbody length and disrupted midbody architecture. Additionally, we show that overexpression of PPP1R2 alters activity of AURKA and PP1 and their phosphorylation state at the centrosome.ResultsOverexpression of PPP1R2 caused an increase in the frequency of supernumerary centrosomes in cells corresponding to aberrant cytokinesis reflected by increased nuclear content and cellular ploidy. Furthermore, AURKA, PP1, phospho PPP1R2, and PPP1R2 were all localized to the midbody at telophase, and PP1 localization there was dependent on binding of PPP1R2 with PP1 and AURKA as well as its phosphorylation state. Additionally, overexpression of both PPP1R2 and its C-terminal AURKA binding site altered enzymatic activity of AURKA and PP1 at the centrosome and disrupted central spindle structure.ConclusionsResults from our study reveal the involvement of PPP1R2 in coordinating PP1 and AURKA activity during cytokinesis. Overexpression of PPP1R2 or its mutants disrupted the midbody at cytokinesis causing accumulation of centrosomes in cells. PPP1R2 recruited PP1 to the midbody and interference with its targeting resulted in elongated and severely disrupted central spindles supporting an important role for PPP1R2 in cytokinesis.

Dataset Information

Centrosome/spindle pole-associated protein regulates cytokinesis via promoting the recruitment of MyoGEF to the central spindle.

Publications

Centrosome/spindle pole-associated protein regulates cytokinesis via promoting the recruitment of MyoGEF to the central spindle.

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