MPF governs the assembly and contraction of actomyosin rings by activating RhoA and MAPK during chemical-induced cytokinesis of goat oocytes.

Yan-Guang Wu,De-Li Wei,Jing-He Tan,Guo-Cheng Lan,Ping Zhou,Qing Li,Hui-Li Wang,Da Gao,Neil A Hotchin

doi:10.1371/journal.pone.0012706

Yan-Guang Wu, De-Li Wei + Show 7 more

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https://doi.org/10.1371/journal.pone.0012706

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Journal: PloS one	Publication Date: Sep 13, 2010
Citations: 35	License type: CC BY 4.0

Affiliation: Shandong Agricultural University

Abstract

The interplay between maturation-promoting factor (MPF), mitogen-activated protein kinase (MAPK) and Rho GTPase during actin-myosin interactions has yet to be determined. The mechanism by which microtubule disrupters induce the formation of ooplasmic protrusion during chemical-assisted enucleation of mammalian oocytes is unknown. Moreover, a suitable model is urgently needed for the study of cytokinesis. We have established a model of chemical-induced cytokinesis and have studied the signaling events leading to cytokinesis using this model. The results suggested that microtubule inhibitors activated MPF, which induced actomyosin assembly (formation of ooplasmic protrusion) by activating RhoA and thus MAPK. While MAPK controlled actin recruitment on its own, MPF promoted myosin enrichment by activating RhoA and MAPK. A further chemical treatment of oocytes with protrusions induced constriction of the actomyosin ring by inactivating MPF while activating RhoA. In conclusion, the present data suggested that the assembly and contraction of the actomyosin ring were two separable steps: while an increase in MPF activity promoted the assembly through RhoA-mediated activation of MAPK, a decrease in MPF activity triggered contraction of the ring by activating RhoA.

Highlights

Cytokinesis is mediated by a dynamic interplay between the microtubules of the mitotic spindle, the actomyosin cytoskeleton and membrane fusion events [1]
The results suggested that the assembly and contraction of the ring were two separable steps: while an increase in maturation-promoting factor (MPF) activities promoted the assembly through RhoA-mediated activation of mitogen-activated protein kinase (MAPK), a decrease in MPF activity induced the contraction of the ring by activating RhoA
Demecolcine induced ooplasmic protrusion by increasing MPF and MAPK activities by activating MAD2 While over 80% of the oocytes treated with demecolcine, MG132 (5-mM) or caffeine (1-mM) formed protrusions in the absence of ROS, less than 5% did in the presence of 400-mM ROS

Summary

Introduction

Cytokinesis is mediated by a dynamic interplay between the microtubules of the mitotic spindle, the actomyosin cytoskeleton and membrane fusion events [1]. While studies suggest that a local minimum of microtubule density or microtubule depolymerization induces the formation of contractile rings through activation of RhoA [2,3], how RhoA is activated has yet to be determined. Both the maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) were found to regulate actin-myosin interactions [4,5,6], interplay between these two kinases in this context has not been reported. Unlike other cell cycle events, cytokinesis has been resistant to in vitro biochemical approaches, making research progress very slow [7]. A powerful in vitro model is urgently needed to dissect out the different steps and molecules involved in cytokinesis

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