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???displayArticle.abstract??? MELK has been implicated in a large variety of functions. Because its level is elevated in cancer tissues and it is involved in cell proliferation, MELK is considered as a potential therapeutic target for cancers. In a recent, study we have shown that MELK is involved in cytokinesis in early Xenopus laevis embryos. MELK dynamically accumulates at the cell cortex including a narrow band corresponding to the presumptive division furrow shortly before cytokinesis onset. MELK co-localizes and interacts with anillin an important regulator of cytokinesis. In addition, MELK overexpression interferes with accumulation at the cleavage furrow of activated Rho GTPase another crucial regulator of cytokinesis. Interestingly, our study also revealed that a transition implying a change in the direction of asymmetric furrow ingression occurs during early development. After this transition, MELK, as well as other proteins involved in cytokinesis, do not localize anymore as a band at the equatorial cortex but still localizes at the cell cortex. Our results indicate that cortical localization is an important feature of MELK in X. laevis embryos.
Figure 1. ME LK localization in epithelial cells of Xenopus gastrula embryos. (A) Indirect immunofluorescence with anti-MELK antibodies. Endogenous
MELK is detected at the cell cortex in interphase cell (arrowhead) and further accumulates at the cell cortex at the metaphase to anaphase transition
(m: metaphase, a: anaphase). The yellow line on the scheme at the bottom indicates the position of the confocal plane relative to the cell surface. DN A
(blue) which is situated more profoundly in the cells was merged with overlaying ME LK signal. (B and C) The mRNA coding for GFP tagged ME LK inactive
mutant (GFP-MELK K/R) which does not induce cytokinesis failure was microinjected in an embryo at the two cell stage and GFP-MELK K/R was
followed in a live gastrulaembryo. Two confocal planes taken at the same time are shown. GFP-MELK K/R is localized at the cell cortex of interphase
cells (i: interphase cell, arrowhead in b and c) and further accumulates at the cell cortex in cytokinetic cell (cyt). Note that the apical domain of the
cytokinetic cell is beginning its division whereas its baso-lateral membrane is already divided. * and ** indicate the two forming daughter cells to
facilitate analysis of the original figure and the related scheme at the bottom.
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