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

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.

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

Development ◽  
2001 ◽  
Vol 128 (21) ◽  
pp. 4349-4359 ◽  
Author(s):  
Mike Boxem ◽  
Sander van den Heuvel

We have investigated the regulation of cell-cycle entry in C. elegans, taking advantage of its largely invariant and completely described pattern of somatic cell divisions. In a genetic screen, we identified mutations in cyd-1 cyclin D and cdk-4 Cdk4/6. Recent results indicated that during Drosophila development, cyclin D-dependent kinases regulate cell growth rather than cell division. However, our data indicate that C. elegans cyd-1 primarily controls G1 progression. To investigate whether cyd-1 and cdk-4 solely act to overcome G1 inhibition by retinoblastoma family members, we constructed double mutants that completely eliminate the function of the retinoblastoma family and cyclin D-Cdk4/6 kinases. Inactivation of lin-35 Rb, the single Rb-related gene in C. elegans, substantially reduced the DNA replication and cell-division defects in cyd-1 and cdk-4 mutant animals. These results demonstrate that lin-35 Rb is an important negative regulator of G1/S progression and probably a downstream target for cyd-1 and cdk-4. However, as the suppression by lin-35 Rb is not complete, cyd-1 and cdk-4 probably have additional targets. An additional level of control over G1 progression is provided by Cip/Kip kinase inhibitors. We demonstrate that lin-35 Rb and cki-1 Cip/Kip contribute non-overlapping levels of G1/S inhibition in C. elegans. Surprisingly, loss of cki-1, but not lin-35, results in precocious entry into S phase. We suggest that a rate limiting role for cki-1 Cip/Kip rather than lin-35 Rb explains the lack of cell-cycle phenotype of lin-35 mutant animals.


Author(s):  
Ye Hong ◽  
Hongtao Zhang ◽  
Anton Gartner

Accurate chromosome segregation requires the removal of all chromatin bridges, which link chromosomes before cell division. When chromatin bridges fail to be removed, cell cycle progression may halt, or cytokinesis failure and ensuing polyploidization may occur. Conversely, the inappropriate severing of chromatin bridges leads to chromosome fragmentation, excessive genome instability at breakpoints, micronucleus formation, and chromothripsis. In this mini-review, we first describe the origins of chromatin bridges, the toxic processing of chromatin bridges by mechanical force, and the TREX1 exonuclease. We then focus on the abscission checkpoint (NoCut) which can confer a transient delay in cytokinesis progression to facilitate bridge resolution. Finally, we describe a recently identified mechanism uncovered in C. elegans where the conserved midbody associated endonuclease LEM-3/ANKLE1 is able to resolve chromatin bridges generated by various perturbations of DNA metabolism at the final stage of cell division. We also discuss how LEM-3 dependent chromatin bridge resolution may be coordinated with abscission checkpoint (NoCut) to achieve an error-free cleavage, therefore acting as a “last chance saloon” to facilitate genome integrity and organismal survival.


2003 ◽  
Vol 160 (7) ◽  
pp. 1093-1103 ◽  
Author(s):  
Joseph J. Tasto ◽  
Jennifer L. Morrell ◽  
Kathleen L. Gould

Anillin is a conserved protein required for cell division (Field, C.M., and B.M. Alberts. 1995. J. Cell Biol. 131:165–178; Oegema, K., M.S. Savoian, T.J. Mitchison, and C.M. Field. 2000. J. Cell Biol. 150:539–552). One fission yeast homologue of anillin, Mid1p, is necessary for the proper placement of the division site within the cell (Chang, F., A. Woollard, and P. Nurse. 1996. J. Cell Sci. 109(Pt 1):131–142; Sohrmann, M., C. Fankhauser, C. Brodbeck, and V. Simanis. 1996. Genes Dev. 10:2707–2719). Here, we identify and characterize a second fission yeast anillin homologue, Mid2p, which is not orthologous with Mid1p. Mid2p localizes as a single ring in the middle of the cell after anaphase in a septin- and actin-dependent manner and splits into two rings during septation. Mid2p colocalizes with septins, and mid2Δ cells display disorganized, diffuse septin rings and a cell separation defect similar to septin deletion strains. mid2 gene expression and protein levels fluctuate during the cell cycle in a sep1- and Skp1/Cdc53/F-box (SCF)–dependent manner, respectively, implying that Mid2p activity must be carefully regulated. Overproduction of Mid2p depolarizes cell growth and affects the organization of both the septin and actin cytoskeletons. In the presence of a nondegradable Mid2p fragment, the septin ring is stabilized and cell cycle progression is delayed. These results suggest that Mid2p influences septin ring organization at the site of cell division and its turnover might normally be required to permit septin ring disassembly.


Development ◽  
2000 ◽  
Vol 127 (23) ◽  
pp. 5071-5082 ◽  
Author(s):  
E.T. Kipreos ◽  
S.P. Gohel ◽  
E.M. Hedgecock

In multicellular eukaryotes, a complex program of developmental signals regulates cell growth and division by controlling the synthesis, activation and degradation of G(1) cell cycle regulators. Here we describe the lin-23 gene of Caenorhabditis elegans, which is required to restrain cell proliferation in response to developmental cues. In lin-23 null mutants, all postembryonic blast cells undergo extra divisions, creating supernumerary cells that can differentiate and function normally. In contrast to the inability to regulate the extent of blast cell division in lin-23 mutants, the timing of initial cell cycle entry of blast cells is not affected. lin-23 encodes an F-box/WD-repeat protein that is orthologous to the Saccharomyces cerevisiae gene MET30, the Drosophila melanogaster gene slmb and the human gene betaTRCP, all of which function as components of SCF ubiquitin-ligase complexes. Loss of function of the Drosophila slmb gene causes the growth of ectopic appendages in a non-cell autonomous manner. In contrast, lin-23 functions cell autonomously to negatively regulate cell cycle progression, thereby allowing cell cycle exit in response to developmental signals.


2014 ◽  
Author(s):  
Chandrika Gowda ◽  
Chunhua Song ◽  
Mansi Sachdev ◽  
Xiaokang Pan ◽  
Yali Ding ◽  
...  

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