scholarly journals APC/CFZR-1 Controls SAS-5 Levels to Regulate Centrosome Duplication in Caenorhabditis elegans

2017 ◽  
Author(s):  
Jeffrey C. Medley ◽  
Lauren E. DeMeyer ◽  
Megan M. Kabara ◽  
Mi Hye Song
Keyword(s):  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Ubiquitin Proteasome System ◽  
Mitotic Cell ◽  
Early Embryo ◽  
Negative Regulator ◽  
Centrosome Duplication ◽  
Microtubule Organizing Center ◽  
Protein Levels ◽  
And Function

ABSTRACTAs the primary microtubule-organizing center, centrosomes play a key role in establishing mitotic bipolar spindles that secure correct transmission of genomic content. For the fidelity of cell division, centrosome number must be strictly controlled by duplicating only once per cell cycle. Proper levels of centrosome proteins are shown to be critical for normal centrosome number and function. Overexpressing core centrosome factors leads to extra centrosomes, while depleting these factors results in centrosome duplication failure. In this regard, protein turnover by the ubiquitin-proteasome system provides a vital mechanism for the regulation of centrosome protein levels. Here, we report that FZR-1, the Caenorhabditis elegans homolog of Cdh1/Hct1/Fzr, a co-activator of the anaphase promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase, functions as a negative regulator of centrosome duplication in the Caenorhabditis elegans embryo. During mitotic cell division in the early embryo, FZR-1 is associated with centrosomes and enriched at nuclei. Loss of fzr-1 function restores centrosome duplication and embryonic viability to the hypomorphic zyg-1(it25) mutant, in part, through elevated levels of SAS-5 at centrosomes. Our data suggest that the APC/CFZR-1 regulates SAS-5 levels by directly recognizing the conserved KEN-box motif, contributing to proper centrosome duplication. Together, our work shows that FZR-1 plays a conserved role in regulating centrosome duplication in Caenorhabditis elegans.

scholarly journals The UNC-45 chaperone mediates sarcomere assembly through myosin degradation in Caenorhabditis elegans

2007 ◽  
Vol 177 (2) ◽  
pp. 205-210 ◽  
Author(s):  
Megan L. Landsverk ◽  
Shumin Li ◽  
Alex H. Hutagalung ◽  
Ayaz Najafov ◽  
Thorsten Hoppe ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Proteasome Inhibition ◽  
Thick Filament ◽  
Ubiquitin Proteasome System ◽  
Loss Of Function ◽  
Cellular Processes ◽  
Ubiquitin Proteasome ◽  
Myosin Motors ◽  
And Function ◽  
Sarcomere Assembly

Myosin motors are central to diverse cellular processes in eukaryotes. Homologues of the myosin chaperone UNC-45 have been implicated in the assembly and function of myosin-containing structures in organisms from fungi to humans. In muscle, the assembly of sarcomeric myosin is regulated to produce stable, uniform thick filaments. Loss-of-function mutations in Caenorhabditis elegans UNC-45 lead to decreased muscle myosin accumulation and defective thick filament assembly, resulting in paralyzed animals. We report that transgenic worms overexpressing UNC-45 also display defects in myosin assembly, with decreased myosin content and a mild paralysis phenotype. We find that the reduced myosin accumulation is the result of degradation through the ubiquitin/proteasome system. Partial proteasome inhibition is able to restore myosin protein and worm motility to nearly wild-type levels. These findings suggest a mechanism in which UNC-45–related proteins may contribute to the degradation of myosin in conditions such as heart failure and muscle wasting.

scholarly journals Vaccinia-Related Kinase 2 Controls the Stability of the Eukaryotic Chaperonin TRiC/CCT by Inhibiting the Deubiquitinating Enzyme USP25

2015 ◽  
Vol 35 (10) ◽  
pp. 1754-1762 ◽  
Author(s):  
Sangjune Kim ◽  
Dohyun Lee ◽  
Juhyun Lee ◽  
Haengjin Song ◽  
Hyo-Jin Kim ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Ubiquitin Proteasome System ◽  
Mutant Protein ◽  
Critical Pathway ◽  
Interacting Protein ◽  
Protein Levels ◽  
Functional Regulation ◽  
The Stability ◽  
And Function ◽  
Polyglutamine Protein

Molecular chaperones monitor the proper folding of misfolded proteins and function as the first line of defense against mutant protein aggregation in neurodegenerative diseases. The eukaryotic chaperonin TRiC is a potent suppressor of mutant protein aggregation and toxicity in early stages of disease progression. Elucidation of TRiC functional regulation will enable us to better understand the pathological mechanisms of neurodegeneration. We have previously shown that vaccinia-related kinase 2 (VRK2) downregulates TRiC protein levels through the ubiquitin-proteasome system by recruiting the E3 ligase COP1. However, although VRK2 activity was necessary in TRiC downregulation, the phosphorylated substrate was not determined. Here, we report that USP25 is a novel TRiC interacting protein that is also phosphorylated by VRK2. USP25 catalyzed deubiquitination of the TRiC protein and stabilized the chaperonin, thereby reducing accumulation of misfolded polyglutamine protein aggregates. Notably, USP25 deubiquitinating activity was suppressed when VRK2 phosphorylated the Thr680, Thr727, and Ser745residues. Impaired USP25 deubiquitinating activity after VRK2-mediated phosphorylation may be a critical pathway in TRiC protein destabilization.

scholarly journals Casein Kinase II is Required for Proper Cell Division and Acts as a Negative Regulator of Centrosome Duplication in C. elegans Embryos

2016 ◽  
Author(s):  
Jeffrey C. Medley ◽  
Megan M. Kabara ◽  
Michael D. Stubenvoll ◽  
Lauren E. DeMeyer ◽  
Mi Hye Song
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Cycle Progression ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Negative Regulator ◽  
Centrosome Duplication ◽  
Dependent Manner ◽  
C Elegans ◽  
Mother Centriole

Summary statementThe conserved protein kinase CK2 negatively regulates centrosome assembly and is required for proper cell cycle progression and cytokinesis in early C. elegans embryos.AbstractCentrosomes are the primary microtubule-organizing centers that orchestrate microtubule dynamics during the cell cycle. The correct number of centrosomes is pivotal for establishing bipolar mitotic spindles that ensure accurate segregation of chromosomes. Thus, centrioles must duplicate once per cell cycle, one daughter per mother centriole, the process of which requires highly coordinated actions among core factors and modulators. Protein phosphorylation is shown to regulate the stability, localization and activity of centrosome proteins. Here, we report the function of Casein Kinase II (CK2) in early C. elegans embryos. The catalytic subunit (KIN-3/CK2α) of CK2 localizes to nuclei, centrosomes and midbodies. Inactivating CK2 leads to cell division defects, including chromosome missegregation, cytokinesis failure and aberrant centrosome behavior. Furthermore, depletion or inhibiting kinase activity of CK2 results in elevated ZYG-1 levels at centrosomes, restoring centrosome duplication and embryonic viability to zyg-1 mutants. Our data suggest that CK2 functions in cell division and negatively regulates centrosome duplication in a kinase-dependent manner.

scholarly journals Sufu negatively regulates both initiations of centrosome duplication and DNA replication

2021 ◽  
Vol 118 (28) ◽  
pp. e2026421118
Author(s):  
Tenghan Zhuang ◽  
Boyan Zhang ◽  
Yihong Song ◽  
Fan Huang ◽  
Wangfei Chi ◽  
...  
Keyword(s):  
Dna Replication ◽  
Negative Regulator ◽  
Centrosome Duplication ◽  
Canonical Function ◽  
Multipolar Spindle ◽  
Suppressor Of Fused ◽  
Serum Stimulation ◽  
Gli Proteins ◽  
Origin Licensing ◽  
And Function

Centrosome duplication and DNA replication are two pivotal events that higher eukaryotic cells use to initiate proliferation. While DNA replication is initiated through origin licensing, centrosome duplication starts with cartwheel assembly and is partly controlled by CP110. However, the upstream coordinator for both events has been, until now, a mystery. Here, we report that suppressor of fused protein (Sufu), a negative regulator of the Hedgehog (Hh) pathway playing a significant role in restricting the trafficking and function of glioma-related (Gli) proteins, acts as an upstream switch by facilitating CP110 phosphorylation by CDK2, promoting intranuclear Cdt1 degradation and excluding prereplication complex (pre-RC) components from chromosomes, independent of its canonical function in the Hh pathway. We found that Sufu localizes to both the centrosome and the nucleus and that knockout of Sufu induces abnormalities including centrosome amplification, increased nuclear size, multipolar spindle formation, and polyploidy. Serum stimulation promotes the elimination of Sufu from the centrosome by vesicle release at the ciliary tip and from the nucleus via protein degradation, which allows centrosome duplication and DNA replication to proceed. Collectively, this work reveals a mechanism through which Sufu negatively regulates the G1-S transition.

scholarly journals Casein kinase II is required for proper cell division and acts as a negative regulator of centrosome duplication inCaenorhabditiselegansembryos

Biology Open ◽  
2016 ◽  
Vol 6 (1) ◽  
pp. 17-28 ◽  
Author(s):  
Jeffrey C. Medley ◽  
Megan M. Kabara ◽  
Michael D. Stubenvoll ◽  
Lauren E. DeMeyer ◽  
Mi Hye Song
Keyword(s):  
Cell Division ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Negative Regulator ◽  
Centrosome Duplication

scholarly journals CRISPR/Cas9 genome editing system confirms centriolin’s role in cytokinesis

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Eric Seronick ◽  
Jae Son ◽  
Cameron Michael ◽  
Hannah Fogg ◽  
Zeynep Gromley ◽  
...  
Keyword(s):  
Cell Division ◽  
Genome Editing ◽  
Cell Cycle Progression ◽  
Primary Cilia ◽  
Effective Means ◽  
Mrna Level ◽  
Microtubule Organizing Center ◽  
Gene Encoding ◽  
Protein Levels ◽  
Organizing Center

Abstract Objective In addition to its function as the microtubule organizing center of the cell, the centrosome has functions in many other cellular processes including primary cilia formation, DNA damage checkpoints, and cell cycle progression. But the role of individual components of the centrosome in these processes remains unclear. Previous studies used siRNA (small interfering RNA) to “knock down” protein levels of the centrosome component centriolin, resulting in failed cytokinesis. Since this approach was transient, only targeting centriolin at the mRNA level, we sought to confirm these findings by permanently disrupting the gene encoding centriolin using the CRISPR/Cas9 system of genome editing. Results This study provides evidence that the CRISPR/Cas9 system is capable of effectively reducing centriolin protein levels in the cell. Furthermore, this disruption leads to a failure of cytokinesis that is reminiscent of the phenotype previously reported for the siRNA-mediated disruption of centriolin. Furthermore, no additional defects in cell division were observed, consistent with results seen with previous siRNA studies. We conclude that the CRISPR/Cas9 system is an effective means of permanently removing the cellular pools of centriolin and that the disruption of centriolin at both the mRNA level and genomic level lead to similar cell division defects.

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