scholarly journals Albatross/FBF1 contributes to both centriole duplication and centrosome separation

2018 ◽  
Vol 23 (12) ◽  
pp. 1023-1042 ◽  
Author(s):  
Akihito Inoko ◽  
Tomoki Yano ◽  
Tatsuo Miyamoto ◽  
Shinya Matsuura ◽  
Tohru Kiyono ◽  
...  
Keyword(s):  
Centriole Duplication ◽  
Centrosome Separation

scholarly journals Cdk2 and Cdk4 Regulate the Centrosome Cycle and Are Critical Mediators of Centrosome Amplification in p53-Null Cells

2009 ◽  
Vol 30 (3) ◽  
pp. 694-710 ◽  
Author(s):  
Arsene M. Adon ◽  
Xiangbin Zeng ◽  
Mary K. Harrison ◽  
Stacy Sannem ◽  
Hiroaki Kiyokawa ◽  
...  
Keyword(s):  
Gene Knockout ◽  
Chromosome Instability ◽  
Phosphorylation Site ◽  
Centrosome Amplification ◽  
Mutant Form ◽  
Embryonic Fibroblasts ◽  
Centriole Duplication ◽  
Centrosome Separation ◽  
Cdk Phosphorylation ◽  
Duplication Cycle

ABSTRACT The two mitotic centrosomes direct spindle bipolarity to maintain euploidy. Centrosome amplification—the acquisition of ≥3 centrosomes—generates multipolar mitoses, aneuploidy, and chromosome instability to promote cancer biogenesis. While much evidence suggests that Cdk2 is the major conductor of the centrosome cycle and that it mediates centrosome amplification induced by various altered tumor suppressors, the role played by Cdk4 in a normal or deregulated centrosome cycle is unknown. Using a gene knockout approach, we report that Cdk2 and Cdk4 are critical to the centrosome cycle, since centrosome separation and duplication are premature in Cdk2 − / − mouse embryonic fibroblasts (MEFs) and are compromised in Cdk4 − / − MEFs. Additionally, ablation of Cdk4 or Cdk2 abrogates centrosome amplification and chromosome instability in p53-null MEFs. Absence of Cdk2 or Cdk4 prevents centrosome amplification by abrogating excessive centriole duplication. Furthermore, hyperactive Cdk2 and Cdk4 deregulate the licensing of the centrosome duplication cycle in p53-null cells by hyperphosphorylating nucleophosmin (NPM) at Thr199, as evidenced by observations that ablation of Cdk2, Cdk4, or both Cdk2 and Cdk4 abrogates that excessive phosphorylation. Since a mutant form of NPM lacking the G1 Cdk phosphorylation site (NPMT199A) prevents centrosome amplification to the same extent as ablation of Cdk2 or Cdk4, we conclude that the Cdk2/Cdk4/NPM pathway is a major guardian of centrosome dysfunction and genomic integrity.

scholarly journals Drosophila centrocortin is dispensable for centriole duplication but contributes to centrosome separation

2021 ◽  
Author(s):  
Dipen S. Mehta ◽  
Pearl V. Ryder ◽  
Jina Lee ◽  
Hala Zein-Sabatto ◽  
Dorothy A. Lerit
Keyword(s):  
Mitotic Spindle ◽  
Time Lapse ◽  
Prior Work ◽  
Microtubule Organizing Centers ◽  
Centriole Duplication ◽  
Centrosome Separation ◽  
Control Versus ◽  
Kinetics Of

Centrosomes are microtubule-organizing centers that duplicate exactly once to organize the bipolar mitotic spindle required for error-free mitosis. Prior work indicated that Drosophila centrocortin ( cen ) is required for normal centrosome separation, although a role in centriole duplication was not closely examined. Through time-lapse recordings of rapid syncytial divisions, we monitored centriole duplication and the kinetics of centrosome separation in control versus cen null embryos. Our data suggest that although cen is dispensable for centriole duplication, it contributes to centrosome separation.

scholarly journals Drosophila centrocortin is dispensable for centriole duplication but contributes to centrosome separation

2021 ◽  
Author(s):  
Dipen S Mehta ◽  
Hala Zein-Sabatto ◽  
Pearl V Ryder ◽  
Jina Lee ◽  
Dorothy A Lerit
Keyword(s):  
Mitotic Spindle ◽  
Time Lapse ◽  
Prior Work ◽  
Microtubule Organizing Centers ◽  
Centriole Duplication ◽  
Centrosome Separation ◽  
Kinetics Of

Abstract Centrosomes are microtubule-organizing centers that duplicate exactly once to organize the bipolar mitotic spindle required for error-free mitosis. Prior work indicated that Drosophila centrocortin (cen) is required for normal centrosome separation, although a role in centriole duplication was not closely examined. Through time-lapse recordings of rapid syncytial divisions, we monitored centriole duplication and the kinetics of centrosome separation in control vs. cen null embryos. Our data suggest that although cen is dispensable for centriole duplication, it contributes to centrosome separation.

scholarly journals Human Microcephaly Protein RTTN Is Required for Proper Mitotic Progression and Correct Spindle Position

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1441
Author(s):  
En-Ju Chou ◽  
Tang K. Tang
Keyword(s):  
Brain Size ◽  
Neurodevelopmental Disorder ◽  
Mitotic Progression ◽  
Centriole Duplication ◽  
Spindle Poles ◽  
Multipolar Spindles ◽  
Mitotic Abnormalities ◽  
Cortical Localization ◽  
Spindle Position ◽  
Autosomal Recessive Primary Microcephaly

Autosomal recessive primary microcephaly (MCPH) is a complex neurodevelopmental disorder characterized by a small brain size with mild to moderate intellectual disability. We previously demonstrated that human microcephaly RTTN played an important role in regulating centriole duplication during interphase, but the role of RTTN in mitosis is not fully understood. Here, we show that RTTN is required for normal mitotic progression and correct spindle position. The depletion of RTTN induces the dispersion of the pericentriolar protein γ-tubulin and multiple mitotic abnormalities, including monopolar, abnormal bipolar, and multipolar spindles. Importantly, the loss of RTTN altered NuMA/p150Glued congression to the spindle poles, perturbed NuMA cortical localization, and reduced the number and the length of astral microtubules. Together, our results provide a new insight into how RTTN functions in mitosis.

scholarly journals Mdm2-Mediated Downmodulation of GRK2 Restricts Centrosome Separation for Proper Chromosome Congression

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 729
Author(s):  
Clara Reglero ◽  
Belén Ortiz del Castillo ◽  
Verónica Rivas ◽  
Federico Mayor ◽  
Petronila Penela
Keyword(s):  
Hippo Pathway ◽  
Growth Factor Receptor ◽  
Receptor Kinase ◽  
Egfr Signaling ◽  
Polyubiquitin Chains ◽  
Centrosome Separation ◽  
Chromosome Congression ◽  
Epidermal Growth ◽  
The Hippo Pathway ◽  
G Protein Coupled

The timing of centrosome separation and the distance moved apart influence the formation of the bipolar spindle, affecting chromosome stability. Epidermal growth factor receptor (EGFR) signaling induces early centrosome separation through downstream G protein-coupled receptor kinase GRK2, which phosphorylates the Hippo pathway component MST2 (Mammalian STE20-like protein kinase 2), in turn allowing NIMA kinase Nek2A activation for centrosomal linker disassembly. However, the mechanisms that counterbalance centrosome disjunction and separation remain poorly understood. We unveil that timely degradation of GRK2 by the E3 ligase Mdm2 limits centrosome separation in the G2. Both knockout expression and catalytic inhibition of Mdm2 result in GRK2 accumulation and enhanced centrosome separation before mitosis onset. Phosphorylation of GRK2 on residue S670 enables a complex pattern of non-K48-linked polyubiquitin chains assembled by Mdm2, which correlate with kinase protein degradation. Remarkably, GRK2-S670A protein fails to phosphorylate MST2 despite overcoming Mdm2-dependent degradation, which results in defective centrosome separation, shorter spindles, and abnormal chromosome congression. Conversely, extra levels of wild-type kinase in the G2 cause increased inter-centrosome distances with longer spindles, also converging in congression issues. Our findings show that the signals enabling activity of the GRK2/MST2/Nek2A axis for separation also switches on Mdm2 degradation of GRK2 to ensure accurate centrosome dynamics and proper mitotic spindle functionality.

scholarly journals Drosophila Ana2 is a conserved centriole duplication factor

2010 ◽  
Vol 188 (3) ◽  
pp. 313-323 ◽  
Author(s):  
Naomi R. Stevens ◽  
Jeroen Dobbelaere ◽  
Kathrin Brunk ◽  
Anna Franz ◽  
Jordan W. Raff
Keyword(s):  
Drosophila Melanogaster ◽  
Caenorhabditis Elegans ◽  
De Novo ◽  
Protein Family ◽  
Centriole Duplication

In Caenorhabditis elegans, five proteins are required for centriole duplication: SPD-2, ZYG-1, SAS-5, SAS-6, and SAS-4. Functional orthologues of all but SAS-5 have been found in other species. In Drosophila melanogaster and humans, Sak/Plk4, DSas-6/hSas-6, and DSas-4/CPAP—orthologues of ZYG-1, SAS-6, and SAS-4, respectively—are required for centriole duplication. Strikingly, all three fly proteins can induce the de novo formation of centriole-like structures when overexpressed in unfertilized eggs. Here, we find that of eight candidate duplication factors identified in cultured fly cells, only two, Ana2 and Asterless (Asl), share this ability. Asl is now known to be essential for centriole duplication in flies, but no equivalent protein has been found in worms. We show that Ana2 is the likely functional orthologue of SAS-5 and that it is also related to the vertebrate STIL/SIL protein family that has been linked to microcephaly in humans. We propose that members of the SAS-5/Ana2/STIL family of proteins are key conserved components of the centriole duplication machinery.

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