The Greatwall-Endosulfine Switch Accelerates Autophagic Flux during the Cell Divisions Leading to G1 Arrest and Entry into Quiescence in Fission Yeast.

Entry into quiescence in the fission yeast is induced by nitrogen starvation. In the absence of nitrogen, proliferating fission yeast cells divide twice without cell growth and undergo cell cycle arrest in G1 before becoming G0 quiescent cells. Under these conditions, autophagy is induced to produce enough nitrogen for the two successive cell divisions that take place before the G1 arrest.

Nutritional Control of Cell Size by the Greatwall-Endosulfine-PP2A·B55 Pathway.

Proliferating cells adjust their cell size depending on the nutritional environment. Cells are large in rich media and small in poor media. This physiological response has been demonstrated in both unicellular and multicellular organisms.

Fission yeast TORC1 prevents eIF2α phosphorylation in response to nitrogen and amino acids via Gcn2 kinase.

Serine 51 phosphorylation of the eukaryotic initiation factor-2α (eIF2α) is an important mechanism involved in blocking general protein synthesis in response to diverse types of stress. In fission yeast, three kinases (Hri1, Hri2 and Gcn2) can phosphorylate eIF2α at serine 51. In this study, we show that Tor2, as part of the TORC1 complex, prevents the phosphorylation of eIF2α in cells growing in the presence of nitrogen and amino acids.

Slk1 is a meiosis-specific Sid2-related kinase that coordinates meiotic nuclear division with growth of the forespore membrane.

Septation and spore formation in fission yeast are compartmentalization processes that occur during the mitotic and meiotic cycles, and that are regulated by the septation initiation network (SIN). In mitosis, activation of Sid2 protein kinase transduces the signal from the spindle pole body (SPB) to the middle of the cell in order to promote the constriction of the actomyosin ring. Concomitant with ring contraction, membrane vesicles are added at the cleavage site to enable the necessary expansion of the cell membrane.