Jaspersen, S. L. et al. A late mitotic regulatory network controlling cyclin destruction in Saccharomyces cerevisiae. Mol. Biol. Cell 9, 2803-2817

Department of Physiology, University of California, San Francisco, California 94143-0444, USA.
Molecular Biology of the Cell (Impact Factor: 4.55). 11/1998; 9(10):2803-17. DOI: 10.1091/mbc.9.10.2803
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ABSTRACT Exit from mitosis requires the inactivation of mitotic cyclin-dependent kinase-cyclin complexes, primarily by ubiquitin-dependent cyclin proteolysis. Cyclin destruction is regulated by a ubiquitin ligase known as the anaphase-promoting complex (APC). In the budding yeast Saccharomyces cerevisiae, members of a large class of late mitotic mutants, including cdc15, cdc5, cdc14, dbf2, and tem1, arrest in anaphase with a phenotype similar to that of cells expressing nondegradable forms of mitotic cyclins. We addressed the possibility that the products of these genes are components of a regulatory network that governs cyclin proteolysis. We identified a complex array of genetic interactions among these mutants and found that the growth defect in most of the mutants is suppressed by overexpression of SPO12, YAK1, and SIC1 and is exacerbated by overproduction of the mitotic cyclin Clb2. When arrested in late mitosis, the mutants exhibit a defect in cyclin-specific APC activity that is accompanied by high Clb2 levels and low levels of the anaphase inhibitor Pds1. Mutant cells arrested in G1 contain normal APC activity. We conclude that Cdc15, Cdc5, Cdc14, Dbf2, and Tem1 cooperate in the activation of the APC in late mitosis but are not required for maintenance of that activity in G1.

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Available from: Sue Jaspersen, Feb 15, 2014
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    • "It associates with the cytoplasmic face of the SPB, which is embedded in the nuclear envelope (Winey and Bloom 2012). Nud1 recruits other components of the MEN to the SPB, and this localization is critical for MEN activation (Jaspersen et al. 1998; Cenamor et al. 1999; Shou et al. 1999; Visintin and Amon 2001; Molk et al. 2004; Rock and Amon 2011; Valerio-Santiago and Monje-Casas 2011). In fact, Cdc15 regulation of the Mob1–Dbf2 complex is probably mediated by co-association on Nud1 at the SPB. "
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    ABSTRACT: Productive cell proliferation involves efficient and accurate splitting of the dividing cell into two separate entities. This orderly process reflects coordination of diverse cytological events by regulatory systems that drive the cell from mitosis into G1. In the budding yeast Saccharomyces cerevisiae, separation of mother and daughter cells involves coordinated actomyosin ring contraction and septum synthesis, followed by septum destruction. These events occur in precise and rapid sequence once chromosomes are segregated and are linked with spindle organization and mitotic progress by intricate cell cycle control machinery. Additionally, critical paarts of the mother/daughter separation process are asymmetric, reflecting a form of fate specification that occurs in every cell division. This chapter describes central events of budding yeast cell separation, as well as the control pathways that integrate them and link them with the cell cycle.
    Genetics 12/2012; 192(4):1165-202. DOI:10.1534/genetics.112.145516 · 4.87 Impact Factor
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    • "To examine the phosphorylation of Cin8 as a function of cell cycle progression, we used cells expressing Myc-tagged Cin8 that were arrested at different stages of the cell cycle. Fractionation of the cell extracts by SDS-PAGE followed by western blot analysis demonstrated that in cells arrested at late anaphase by any one of several temperature-sensitive mutations [cdc15-2, cdc14-1 (Jaspersen et al., 1998) and cdc5-7 (Park et al., 2003)], Cin8 exhibits a slow-migrating form (Fig. 1A), indicative of protein phosphorylation. This band-shift was observed for Cin8 produced either from a CEN (centromere) or 2 m plasmid tagged with the Myc epitope either at its N-or C-terminus (Fig. 1) and for Cin8– BCP (Gheber et al., 1999) (data not shown). "
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    • "Mitotic exit in budding yeast is driven by a signal transduction cascade called the mitotic exit network (MEN) (Figure 1A) (Jaspersen et al, 1998). Activation of the small GTPase Tem1 is the most upstream event in the initiation of MEN (Lee et al, 2001). "
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    ABSTRACT: The orientation of the mitotic spindle with respect to the polarity axis is crucial for the accuracy of asymmetric cell division. In budding yeast, a surveillance mechanism called the spindle position checkpoint (SPOC) prevents exit from mitosis when the mitotic spindle fails to align along the mother-to-daughter polarity axis. SPOC arrest relies upon inhibition of the GTPase Tem1 by the GTPase-activating protein (GAP) complex Bfa1-Bub2. Importantly, reactions signaling mitotic exit take place at yeast centrosomes (named spindle pole bodies, SPBs) and the GAP complex also promotes SPB localization of Tem1. Yet, whether the regulation of Tem1 by Bfa1-Bub2 takes place only at the SPBs remains elusive. Here, we present a quantitative analysis of Bfa1-Bub2 and Tem1 localization at the SPBs. Based on the measured SPB-bound protein levels, we introduce a dynamical model of the SPOC that describes the regulation of Bfa1 and Tem1. Our model suggests that Bfa1 interacts with Tem1 in the cytoplasm as well as at the SPBs to provide efficient Tem1 inhibition.
    Molecular Systems Biology 05/2012; 8:582. DOI:10.1038/msb.2012.15 · 14.10 Impact Factor
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