APC/C-Cdh1-mediated degradation of the Polo kinase Cdc5 promotes the return of Cdc14 into the nucleolus

Abstract

In the budding yeast Saccharomyces cerevisiae, the protein phosphatase Cdc14 triggers exit from mitosis by promoting the inactivation of cyclin-dependent kinases (CDKs). Cdc14's activity is controlled by Cfi1/Net1, which holds and inhibits the phosphatase in the nucleolus from G1 until metaphase. During anaphase, two regulatory networks, the Cdc14 Early Anaphase Release (FEAR) network and the Mitotic Exit Network (MEN), promote the dissociation of Cdc14 from its inhibitor, allowing the phosphatase to reach its targets throughout the cell. The molecular circuits that trigger the return of Cdc14 into the nucleolus after the completion of exit from mitosis are not known. Here we show that activation of a ubiquitin ligase known as the Anaphase-Promoting Complex or Cyclosome (APC/C) bound to the specificity factor Cdh1 triggers the degradation of the Polo kinase Cdc5, a key factor in releasing Cdc14 from its inhibitor in the nucleolus.[Keywords: Cdc14; Cdc5; cell cycle; mitosis] Supplemental material is available at http://www.genesdev.org.

Mitotic Exit and Separation of Mother and Daughter Cells

“…One mechanistic reason for the transition between APC Cdc20 and APC Cdh1 is that activity of APC Cdc20 is optimally maintained when cyclin-CDK levels are high, while APC Cdh1 function is actually antagonized by mitotic CDK phosphorylation (Zachariae et al 1998;Yeong et al 2000;Toth et al 2007;Holt et al 2008;Pines 2011). Once mitosis is complete, APC Cdh1 helps define the G1 state: it turns off mitotic exit by targeting the polo-family protein kinase Cdc5 for destruction in late M or early G1 and destabilizes mitotic cyclins throughout G1 (Wasch and Cross 2002;Visintin et al 2008).…”

Budding Yeast Swe1 Is Involved in the Control of Mitotic Spindle Elongation and Is Regulated by Cdc14 Phosphatase during Mitosis

“…Inhibition of Cdc15 kinase activity was performed as described (21). SWE1-PK3 cdc15-as1 and SWE1-PK3 CDC14-HA3 cdc15-as1 cells were grown at 25°C, prearrested with 2 g/ml ␣-factor, and released in the presence of 5 M 1NM-PP1 for 2 h to arrest them in late mitosis (88% budded cells with separated nuclei).…”

“…To better understand whether Cdc14 could be directly involved in Swe1 regulation, we performed an immunoprecipitation experiment preparing total protein extracts from cells expressing Swe1-PK3 and Cdc14-HA3 and arrested in late mitosis because of cdc15-as1 allele, an ATP analog-sensitive allele of CDC15 (21). Importantly, Swe1 could specifically immunoprecipitate Cdc14, suggesting that Cdc14 might be the protein phosphatase that dephosphorylates Swe1 in late mitosis (Fig.…”

Protein Phosphatases Drive Mitotic Exit

“…Ptpcd-1 possesses four Plk1 consensus phosphorylation sites and its overexpression could not rescue cytokinesis failure induced by Plk1 depletion (Zineldeen et al, 2009), suggesting that it lies downstream of Plk1. In support of this idea, the yeast homolog of Plk1, Cdc5, regulates Cdc14 phosphorylation and its subcellular localization for mitotic exit (Visintin et al, 2003, Visintin et al, 2008. Based on their midbody co-localization, it is possible that this Plk1/Ptpcd-1 signalling pathway contributes to membrane abscission.…”