The septation initiation network (SIN) is a signalling cascade in Schizosaccharomyces pombe that originates from the spindle pole body (SPB), and is required for cytokinesis during vegetative growth and for spore formation in meiosis. The regulation of SIN during mitosis is fairly well understood and includes the GTPase Spg1p, which is kept in an inactive GDP-bound state during interphase; during mitosis it interacts with Cdc7, thereby activating the downstream SIN kinases Sid1p and Sid2p. However, much less is known with regard to SIN regulation during meiosis. In this study (p. 3149), Andrea Krapp and Viesturs Simanis demonstrate that there are significant differences between mitotic and meiotic regulation of the SIN. First, the GTPase cycle of Spg1p is not sufficient to recruit the SIN kinases to the SPB; instead, elimination of the GTPase-activating protein (GAP) scaffolding factor Byr4p is required to initiate SIN signalling. Furthermore, the authors reveal that several of the core SIN proteins are degraded at different stages of meiosis. The ubiquitin ligase Dma1p is required for degradation of some but not all SIN components and, in addition, has other targets. This suggests that SIN during meiosis is regulated in part through proteolysis, whereas during mitosis, only the degradation of Byr4p has been described. Taken together, the results indicate a complex interplay between phosphorylation and degradation to ensure appropriate activation and silencing of the SIN in order to coordinate spore formation and nuclear division.
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IN THIS ISSUE| 15 July 2014
New insights into SIN in meiosis
Online Issn: 1477-9137
Print Issn: 0021-9533
© 2014. Published by The Company of Biologists Ltd
J Cell Sci (2014) 127 (14): e1404.
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New insights into SIN in meiosis. J Cell Sci 15 July 2014; 127 (14): e1404. doi:
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