scholarly journals The careful control of Polo kinase by APC/C-Ube2C ensures the intercellular transport of germline centrosomes during Drosophila oogenesis

Open Biology ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 200371
Author(s):  
Alexis Leah Braun ◽  
Francesco Meghini ◽  
Gema Villa-Fombuena ◽  
Morgane Guermont ◽  
Elisa Fernandez-Martinez ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Cell Cycle Control ◽  
Underlying Mechanism ◽  
Anaphase Promoting Complex ◽  
Microtubule Nucleation ◽  
Novel Mutations ◽  
Intercellular Transport ◽  
Ubiquitin Ligase Complex ◽  
Nucleation Activity ◽  
Inhibitory Regulation

A feature of metazoan reproduction is the elimination of maternal centrosomes from the oocyte. In animals that form syncytial cysts during oogenesis, including Drosophila and human, all centrosomes within the cyst migrate to the oocyte where they are subsequently degenerated. The importance and the underlying mechanism of this event remain unclear. Here, we show that, during early Drosophila oogenesis, control of the Anaphase Promoting Complex/Cyclosome (APC/C), the ubiquitin ligase complex essential for cell cycle control, ensures proper transport of centrosomes into the oocyte through the regulation of Polo/Plk1 kinase, a critical regulator of the integrity and activity of the centrosome. We show that novel mutations in the APC/C-specific E2, Vihar/Ube2c, that affect its inhibitory regulation on APC/C cause precocious Polo degradation and impedes centrosome transport, through destabilization of centrosomes. The failure of centrosome migration correlates with weakened microtubule polarization in the cyst and allows ectopic microtubule nucleation in nurse cells, leading to the loss of oocyte identity. These results suggest a role for centrosome migration in oocyte fate maintenance through the concentration and confinement of microtubule nucleation activity into the oocyte. Considering the conserved roles of APC/C and Polo throughout the animal kingdom, our findings may be translated into other animals.

scholarly journals From Rabbit Reticulocytes to Clam Oocytes: In Search of the System That Targets Mitotic Cyclins for Degradation

2010 ◽  
Vol 21 (10) ◽  
pp. 1645-1647 ◽  
Author(s):  
Avram Hershko
Keyword(s):  
Cell Cycle ◽  
Ubiquitin Ligase ◽  
Cell Cycle Control ◽  
Anaphase Promoting Complex ◽  
Free System ◽  
Ubiquitin Ligase Complex ◽  
Reticulocyte Lysates ◽  
A Cell ◽  
Specific Degradation ◽  
Rabbit Reticulocytes

By the late 1980s, the basic biochemistry of ubiquitin-mediated protein degradation had already been elucidated by studies that used reticulocyte lysates. However, the scope and biological functions of this system remained largely obscure. Therefore, I became interested at that time in the mechanisms by which mitotic cyclins are degraded in exit from mitosis. Using a cell-free system from clam oocytes that faithfully reproduced cell cycle stage–specific degradation of cyclins, we identified in 1995 a large ubiquitin ligase complex that targets mitotic cyclins for degradation. Subsequent studies in many laboratories showed that this ubiquitin ligase, now called the anaphase-promoting complex/cyclosome, has centrally important roles in many aspects of cell cycle control.

scholarly journals Centrosomal Microtubule Nucleation Activity Is Inhibited by BRCA1-Dependent Ubiquitination

2005 ◽  
Vol 25 (19) ◽  
pp. 8656-8668 ◽  
Author(s):  
Satish Sankaran ◽  
Lea M. Starita ◽  
Aaron C. Groen ◽  
Min Ji Ko ◽  
Jeffrey D. Parvin
Keyword(s):  
Ubiquitin Ligase ◽  
Functional Assay ◽  
Breast Cancers ◽  
Microtubule Nucleation ◽  
Brca1 Protein ◽  
Truncation Mutant ◽  
Lysine Residues ◽  
Nucleation Activity ◽  
Carboxy Terminal

ABSTRACT In this study we find that the function of BRCA1 inhibits the microtubule nucleation function of centrosomes. In particular, cells in early S phase have quiescent centrosomes due to BRCA1 activity, which inhibits the association of γ-tubulin with centrosomes. We find that modification of either of two specific lysine residues (Lys-48 and Lys-344) of γ-tubulin, a known substrate for BRCA1-dependent ubiquitination activity, led to centrosome hyperactivity. Interestingly, mutation of γ-tubulin lysine 344 had a minimal effect on centrosome number but a profound effect on microtubule nucleation function, indicating that the processes regulating centrosome duplication and microtubule nucleation are distinct. Using an in vitro aster formation assay, we found that BRCA1-dependent ubiquitination activity directly inhibits microtubule nucleation by centrosomes. Mutant BRCA1 protein that was inactive as a ubiquitin ligase did not inhibit aster formation by the centrosome. Further, a BRCA1 carboxy-terminal truncation mutant that was an active ubiquitin ligase lacked domains critical for the inhibition of centrosome function. These experiments reveal an important new functional assay regulated by the BRCA1-dependent ubiquitin ligase, and the results suggest that the loss of this BRCA1 activity could cause the centrosome hypertrophy and subsequent aneuploidy typically found in breast cancers.

scholarly journals Exome sequencing of hepatoblastoma reveals novel mutations and cancer genes in the Wnt pathway and ubiquitin ligase complex

Hepatology ◽  
2014 ◽  
Vol 60 (5) ◽  
pp. 1686-1696 ◽  
Author(s):  
Deshui Jia ◽  
Rui Dong ◽  
Ying Jing ◽  
Dan Xu ◽  
Qifeng Wang ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Ubiquitin Ligase ◽  
Wnt Pathway ◽  
Cancer Genes ◽  
Novel Mutations ◽  
Ubiquitin Ligase Complex

scholarly journals Distinct Mechanisms Control the Stability of the Related S-Phase Cyclins Clb5 and Clb6

2006 ◽  
Vol 26 (6) ◽  
pp. 2456-2466 ◽  
Author(s):  
Leisa P. Jackson ◽  
Steven I. Reed ◽  
Steven B. Haase
Keyword(s):  
Ubiquitin Ligase ◽  
S Phase ◽  
Phosphorylation Sites ◽  
Anaphase Promoting Complex ◽  
Functional Differences ◽  
Ubiquitin Ligase Complex ◽  
N Terminus ◽  
Phase Progression ◽  
The Stability ◽  
Related Proteins

ABSTRACT The yeast S-phase cyclins Clb5 and Clb6 are closely related proteins that are synthesized late in G1. Although often grouped together with respect to function, Clb5 and Clb6 exhibit differences in their ability to promote S-phase progression. DNA replication is significantly slowed in clb5Δ mutants but not in clb6Δ mutants. We have examined the basis for the differential functions of Clb5 and Clb6 and determined that unlike Clb5, which is stable until mitosis, Clb6 is degraded rapidly at the G1/S border. N-terminal deletions of CLB6 were hyperstabilized, suggesting that the sequences responsible for directing the destruction of Clb6 reside in the N terminus. Clb6 lacks the destruction box motif responsible for the anaphase promoting complex-mediated destruction of Clb5 but contains putative Cdc4 degron motifs in the N terminus. Clb6 was hyperstabilized in cdc34-3 and cdc4-3 mutants at restrictive temperatures and when S/T-P phosphorylation sites in the N terminus were mutated to nonphosphorylatable residues. Efficient degradation of Clb6 requires the activities of both Cdc28 and Pho85. Finally, hyperstabilized Clb6 expressed from the CLB6 promoter rescued the slow S-phase defect exhibited by clb5Δ cells. Taken together, these findings suggest that the SCFCdc4 ubiquitin ligase complex regulates Clb6 turnover and that the functional differences exhibited by Clb5 and Clb6 arise from the distinct mechanisms controlling their stability.

scholarly journals A Subunit of the Anaphase-Promoting Complex Is a Centromere-Associated Protein in Mammalian Cells

1998 ◽  
Vol 18 (1) ◽  
pp. 468-476 ◽  
Author(s):  
Pia-Marie Jörgensen ◽  
Eva Brundell ◽  
Maria Starborg ◽  
Christer Höög
Keyword(s):  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Chinese Hamster ◽  
Separation Process ◽  
Soluble Form ◽  
Anaphase Promoting Complex ◽  
Mitotic Chromosomes ◽  
Sister Chromatids ◽  
Ubiquitin Ligase Complex ◽  
A Subunit

ABSTRACT Sister chromatids in early mitotic cells are held together mainly by interactions between centromeres. The separation of sister chromatids at the transition between the metaphase and the anaphase stages of mitosis depends on the anaphase-promoting complex (APC), a 20S ubiquitin-ligase complex that targets proteins for destruction. A subunit of the APC, called APC-α in Xenopus (and whose homologs are APC-1, Cut4, BIME, and Tsg24), has recently been identified and shown to be required for entry into anaphase. We now show that the mammalian APC-α homolog, Tsg24, is a centromere-associated protein. While this protein is detected only during the prophase to the anaphase stages of mitosis in Chinese hamster cells, it is constitutively associated with the centromeres in murine cells. We show that there are two forms of this protein in mammalian cells, a soluble form associated with other components of the APC and a centromere-bound form. We also show that both the Tsg24 protein and the Cdc27 protein, another APC component, are bound to isolated mitotic chromosomes. These results therefore support a model in which the APC by ubiquitination of a centromere protein regulates the sister chromatid separation process.

The Ubiquitin-Ligase APC-Cdh1 Is Required for Maintaining Genomic Stability and Is Transcriptional Repressed by AML1/ETO.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1609-1609
Author(s):  
Ralph Waesch ◽  
Dirk Engelbert ◽  
Dominik Schnerch
Keyword(s):  
Ubiquitin Ligase ◽  
Transcriptional Repression ◽  
Genetic Instability ◽  
Kinase Inhibitor ◽  
Cell Cycle Control ◽  
Genomic Stability ◽  
Cyclin B1 ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Cyclin Dependent Kinase Inhibitor

Abstract Accurate DNA replication and chromosome segregation is essential during cell division in order to provide genomic stability and avoid malignant growth. We found that ubiquitin-dependent proteolytic cell cycle control by the E3-ubiquitin-ligase anaphase-promoting complex (APC) activated by Cdh1 (APC-Cdh1) is required for maintaining genomic integrity and viability in proliferating human cells. Lentiviral-delivered stable expression of short hairpins targeted against Cdh1 causes an apoptotic phenotype associated with p53-stabilization and p53-dependent transcriptional up-regulation of the cyclin-dependent kinase inhibitor p21. Cdh1-depleted cells enter mitosis delayed compared to controls suggesting the activation of a DNA-damage checkpoint in S- and G2-phase. Depletion of Cdh1 leads to premature accumulation of cyclin A2 and cyclin B1 in G1- and S-phase. This may interfere with loading of pre-replication-complexes onto origins of replication in G1 and cause chromosomal instability when cells progress into mitosis. In addition, stabilization of the Cdh1 target Aurora A at physiological levels is sufficient to cause centrosome overduplication and subsequent polyploidization in Cdh1 and p53 deficient cells. Genetic instability is a hallmark of cancer cells and deregulation of APC-Cdh1 may be involved, since we observe downregulation of Cdh1 in t(8;21) acute myeloid leukemia. Moreover, expression of AML1/ETO in an inducible system leads to downregulation of Cdh1 indicating transcriptional repression of Cdh1 by AML1/ETO. Consistent with these data AML1/ETO positive cell lines show numerical chromosomal aberrations. Thus, disruption of the central mitotic control machinery leads to genetic instability by several mechanisms and the APC may be an important suppressor of tumor progression in AML1/ETO positive leukemia.

scholarly journals E3 Ubiquitin Ligase APC/CCdh1 Regulation of Phenylalanine Hydroxylase Stability and Function

2020 ◽  
Vol 21 (23) ◽  
pp. 9076
Author(s):  
Apoorvi Tyagi ◽  
Neha Sarodaya ◽  
Kamini Kaushal ◽  
Arun Pandian Chandrasekaran ◽  
Ainsley Mike Antao ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Autosomal Recessive ◽  
Phenylalanine Hydroxylase ◽  
E3 Ubiquitin Ligase ◽  
Anaphase Promoting Complex ◽  
Potential Therapeutic Target ◽  
E3 Ligases ◽  
Ubiquitin Ligase Complex ◽  
Phenylalanine Metabolism ◽  
And Function

Phenylketonuria (PKU) is an autosomal recessive metabolic disorder caused by the dysfunction of the enzyme phenylalanine hydroxylase (PAH). Alterations in the level of PAH leads to the toxic accumulation of phenylalanine in the blood and brain. Protein degradation mediated by ubiquitination is a principal cellular process for maintaining protein homeostasis. Therefore, it is important to identify the E3 ligases responsible for PAH turnover and proteostasis. Here, we report that anaphase-promoting complex/cyclosome-Cdh1 (APC/C)Cdh1 is an E3 ubiquitin ligase complex that interacts and promotes the polyubiquitination of PAH through the 26S proteasomal pathway. Cdh1 destabilizes and declines the half-life of PAH. In contrast, the CRISPR/Cas9-mediated knockout of Cdh1 stabilizes PAH expression and enhances phenylalanine metabolism. Additionally, our current study demonstrates the clinical relevance of PAH and Cdh1 correlation in hepatocellular carcinoma (HCC). Overall, we show that PAH is a prognostic marker for HCC and Cdh1 could be a potential therapeutic target to regulate PAH-mediated physiological and metabolic disorders.

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