A functional analysis of MELK in cell division reveals a transition in the mode of cytokinesis during Xenopus development.

J Cell Sci

UMR 6061 CNRS Université de Rennes 1, IFR140 GFAS, Equipe Développement et Polarité Cellulaires, 2 avenue du Professeur Léon Bernard, CS 34317, 35043 Rennes CEDEX, France.

Published: March 2011

MELK is a serine/threonine kinase involved in several cell processes, including the cell cycle, proliferation, apoptosis and mRNA processing. However, its function remains elusive. Here, we explored its role in the Xenopus early embryo and show by knockdown that xMELK (Xenopus MELK) is necessary for completion of cell division. Consistent with a role in cell division, endogenous xMELK accumulates at the equatorial cortex of anaphase blastomeres. Its relocalization is highly dynamic and correlates with a conformational rearrangement in xMELK. Overexpression of xMELK leads to failure of cytokinesis and impairs accumulation at the division furrow of activated RhoA - a pivotal regulator of cytokinesis. Furthermore, endogenous xMELK associates and colocalizes with the cytokinesis organizer anillin. Unexpectedly, our study reveals a transition in the mode of cytokinesis correlated to cell size and that implicates xMELK. Collectively, our findings disclose the importance of xMELK in cytokinesis during early development and show that the mechanism of cytokinesis changes during Xenopus early development.

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http://dx.doi.org/10.1242/jcs.069567DOI Listing

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