Activity of the APCCdh1 form of the anaphase-promoting complex persists until S phase and prevents the premature expression of Cdc20p

Huang, James N.; Park, Iha; Ellingson, Eric; Littlepage, Laurie E.; Pellman, David

doi:10.1083/jcb.200102007

Cited by 104 publications

(123 citation statements)

References 46 publications

Supporting

Mentioning

106

Contrasting

Unclassified

Order By: Relevance

“…Nevertheless, sporulation is normal when Cdc20 is stabilized by mutation of two consensus degradation motifs, indicating that turnover is not necessary for meiotic progression (Tan et al 2010). In vegetative cells, Cdc20 degradation in late mitosis and early G1 is important for maintaining the order of cell cycle events (Huang et al 2001). Thus, APC-Ama1-mediated degradation of Cdc20 at meiotic exit might help the spore enter or maintain a G0 or early G1 state.…”

Section: Transition To Meiotic Division: Control Of Ndt80mentioning

confidence: 99%

Sporulation in the Budding Yeast Saccharomyces cerevisiae

2011

View full text Add to dashboard Cite

In response to nitrogen starvation in the presence of a poor carbon source, diploid cells of the yeast Saccharomyces cerevisiae undergo meiosis and package the haploid nuclei produced in meiosis into spores. The formation of spores requires an unusual cell division event in which daughter cells are formed within the cytoplasm of the mother cell. This process involves the de novo generation of two different cellular structures: novel membrane compartments within the cell cytoplasm that give rise to the spore plasma membrane and an extensive spore wall that protects the spore from environmental insults. This article summarizes what is known about the molecular mechanisms controlling spore assembly with particular attention to how constitutive cellular functions are modified to create novel behaviors during this developmental process. Key regulatory points on the sporulation pathway are also discussed as well as the possible role of sporulation in the natural ecology of S. cerevisiae. TABLE OF CONTENTS Abstract 737Introduction 738

show abstract

Section: Transition To Meiotic Division: Control Of Ndt80mentioning

confidence: 99%

Sporulation in the Budding Yeast Saccharomyces cerevisiae

2011

View full text Add to dashboard Cite

show abstract

“…This process also requires Cdk1͞Clb kinases (38,39). Similarly, the combined function of both Ime2 and accumulating Cdk1͞Clb kinases may be needed for completely turning off APC Cdh1 in meiosis.…”

Section: Similarities and Differences Of Ime2 With Cdk1͞clnmentioning

confidence: 99%

Inhibition of APC-mediated proteolysis by the meiosis-specific protein kinase Ime2

Bolte

Steigemann²,

Braus³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Proteolysis triggered by the anaphase-promoting complex (APC) is needed for sister chromatid separation and the exit from mitosis. APC is a ubiquitin ligase whose activity is tightly controlled during the cell cycle. To identify factors involved in the regulation of APC-mediated proteolysis, a Saccharomyces cerevisiae GAL-cDNA library was screened for genes whose overexpression prevented degradation of an APC target protein, the mitotic cyclin Clb2. Genes encoding G1, S, and mitotic cyclins were identified, consistent with previous data showing that the cyclin-dependent kinase Cdk1 associated with different cyclins is a key factor for inhibiting APC Cdh1 activity from late-G1 phase until mitosis. In addition, the meiosis-specific protein kinase Ime2 was identified as a negative regulator of APC-mediated proteolysis. Ectopic expression of IME2 in G1 arrested cells inhibited the degradation of mitotic cyclins and of other APC substrates. IME2 expression resulted in the phosphorylation of Cdh1 in G1 cells, indicating that Ime2 and Cdk1 regulate APC Cdh1 in a similar manner. The expression of IME2 in cycling cells inhibited bud formation and caused cells to arrest in mitosis. We show further that Ime2 itself is an unstable protein whose proteolysis occurs independently of the APC and SCF (Skp1͞ Cdc53͞F-box) ubiquitin ligases. Our findings suggest that Ime2 represents an unstable, meiosis-specific regulator of APC Cdh1 .C rucial processes in the cell cycle, such as initiation of DNA replication, separation of sister chromatids, and exit from mitosis, depend on proteolytic degradation of critical regulatory proteins (1-3). Ubiquitin ligases play essential roles in these degradation processes. These enzymes catalyze the formation of chains of ubiquitin on their substrates, thereby targeting them for degradation by the 26S proteasome (4). The anaphasepromoting complex (APC), also known as cyclosome, is a multisubunit complex acting as ubiquitin ligase (5, 6). APC is essential for mitosis, and its activity is tightly cell cycle-regulated. Its activation at the metaphase͞anaphase transition requires its association with the activator protein Cdc20. APC Cdc20 triggers proteolytic degradation of the securin Pds1. Upon Pds1 proteolysis, the separase Esp1 is liberated, cleaves the cohesin subunit Scc1, and thereby triggers sister chromatid separation (7). APC Cdc20 also initiates proteolysis of the S phase cyclin Clb5 and a fraction of mitotic cyclins (8-10). APC Cdc20 activation is inhibited by the spindle assembly checkpoint, which prevents sister chromatid separation upon defects in the mitotic spindle or in the attachment of kinetochores (11).Cdh1 (also termed Hct1) is related to Cdc20 and is needed for complete degradation of mitotic cyclins (12, 13). Cdh1's potential to associate with the APC is controlled by phosphorylation (14, 15). The cyclin-dependent kinase Cdk1 phosphorylates Cdh1, thereby preventing its interaction with APC. A Cdk1-antagonizing phosphatase, Cdc14, is kept inactive in the nucleolus for most of the...

show abstract

“…[20][21][22] Compared with single mutants, the cln1 cln2 double mutant shows severe growth defects, 23,24 indicating a functional overlap between these two cyclins. In fact, the extensive work performed on these cyclins has revealed that they take part in many common functions, such as induction of growth polarization and budding, [25][26][27] SPB duplication, 28 degradation of CDK-inhibitors Far1 and Sic1, [29][30][31][32] inactivation of the APC ubiquitin-ligase complex, 33,34 repression of pheromone-induced transcription or stimulation of pseudohyphal growth. 35 However, in addition to the numerous studies that highlight the similarity between Cln1 and Cln2, several functional differences between them have also been described.…”

Section: Molecular Basis Of the Functional Distinction Between Cln1 Amentioning

confidence: 99%