A novel checkpoint pathway controls actomyosin ring constriction trigger in fission yeast.

Tomás Edreira,Yolanda Sánchez,Elvira Manjón,Rubén Celador

doi:10.7554/elife.59333

Tomás Edreira, Yolanda Sánchez + Show 2 more

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https://doi.org/10.7554/elife.59333

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Abstract

In fission yeast, the septation initiation network (SIN) ensures temporal coordination between actomyosin ring (CAR) constriction with membrane ingression and septum synthesis. However, questions remain about CAR regulation under stress conditions. We show that Rgf1p (Rho1p GEF), participates in a delay of cytokinesis under cell wall stress (blankophor, BP). BP did not interfere with CAR assembly or the rate of CAR constriction, but did delay the onset of constriction in the wild type cells but not in the rgf1Δ cells. This delay was also abolished in the absence of Pmk1p, the MAPK of the cell integrity pathway (CIP), leading to premature abscission and a multi-septated phenotype. Moreover, cytokinesis delay correlates with maintained SIN signaling and depends on the SIN to be achieved. Thus, we propose that the CIP participates in a checkpoint, capable of triggering a CAR constriction delay through the SIN pathway to ensure that cytokinesis terminates successfully.

Highlights

Cytokinesis in fission yeast, as in most eukaryotes, involves the function of a contractile ring of actin filaments and myosin-II (AR) placed between the poles of the mitotic spindle during cell division
The actomyosin ring is assembled before anaphase, whereas its constriction occurs after completion of anaphase (Wu et al, 2003)
Statistical significance was calculated by ANOVA followed by Fisher’s LSD test (n.s. p>0.05; *p

Summary

Introduction

Cytokinesis in fission yeast, as in most eukaryotes, involves the function of a contractile ring of actin filaments and myosin-II (AR) placed between the poles of the mitotic spindle during cell division. We investigate the role of Rgf1p and Rho1p in cytokinesis and show that stress affecting cell wall integrity prevents the completion of cytokinesis on time This inhibition depends on a signaling pathway that involves the Rho1p GEF, Rgf1p, the Rho-GTPase, Rho1p, the ScPkc1p orthologue Pck2p, and the MAP kinase Pmk1p, all components of the cell integrity pathway (CIP). Inactivation of this pathway in stressed cells causes defects in septation (Sengar et al, 1997; Toda et al, 1996; Zaitsevskaya-Carter and Cooper, 1997). We propose that the CIP signaling delays CAR constriction in response to cell wall perturbations to ensure that cytokinesis reaches completion only after the cell has adjusted to the new conditions

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