Abstract
ABSTRACTThe timing of cell division is controlled by the coupled regulation of growth and division. The target of rapamycin (TOR) signalling network synchronises these processes with the environmental setting. Here, we describe a novel interaction of the fission yeast TOR complex 2 (TORC2) with the cytokinetic actomyosin ring (CAR), and a novel role for TORC2 in regulating the timing and fidelity of cytokinesis. Disruption of TORC2 or its localisation results in defects in CAR morphology and constriction. We provide evidence that the myosin II protein Myp2 and the myosin V protein Myo51 play roles in recruiting TORC2 to the CAR. We show that Myp2 and TORC2 are co-dependent upon each other for their normal localisation to the cytokinetic machinery. We go on to show that TORC2-dependent phosphorylation of actin-capping protein 1 (Acp1, a known regulator of cytokinesis) controls CAR stability, modulates Acp1–Acp2 (the equivalent of the mammalian CAPZA–CAPZB) heterodimer formation and is essential for survival upon stress. Thus, TORC2 localisation to the CAR, and TORC2-dependent Acp1 phosphorylation contributes to timely control and the fidelity of cytokinesis and cell division.
Highlights
Target of rapamycin (TOR) signalling plays a key role in modulating the spatial and temporal control of cell growth in response to different environmental conditions
TOR complex 2 (TORC2) controls the integrity of the cytokinetic actomyosin ring (CAR) In order to examine the potential roles that TORC2 might have during actin-dependent cell growth and division (Lancaster and Baum, 2014), we undertook a phenotypic analysis of fission yeast cells lacking RICTORSte20, the core TORC2specific component
Here, we describe a novel TORC2 recruitment to the CAR that plays a role in maintaining the fidelity of cytokinesis in fission yeast
Summary
Target of rapamycin (TOR) signalling plays a key role in modulating the spatial and temporal control of cell growth in response to different environmental conditions. The TOR kinase forms two functionally distinct protein complexes, TOR complex 1 (TORC1) and TORC2 (Laplante and Sabatini, 2012). TORC1 and TORC2 are defined by unique components that are highly conserved across species. TORC1 contains regulatory associated protein of mTOR (RAPTOR, known as RPTOR), and TORC2 contains Sin and rapamycin-insensitive companion of mTOR (RICTOR) (Wullschleger et al, 2006).
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