Mitotic block in HeLa cells by vinblastine: ultrastructural changes in kinetochore-microtubule attachment and in centrosomes

1993 ◽  
Vol 104 (2) ◽  
pp. 261-274 ◽  
Author(s):  
K.L. Wendell ◽  
L. Wilson ◽  
M.A. Jordan
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Mitotic Spindle ◽  
Close Association ◽  
Ultrastructural Changes ◽  
Microtubule Depolymerization ◽  
Metaphase Chromosomes ◽  
Mitotic Block ◽  
Mother And Daughter ◽  
Spindle Microtubules

Previous work from this laboratory has indicated that very low concentrations of vinblastine block HeLa cells at mitosis in the presence of a full complement of microtubules and without major disruption of spindle organization. In the present study we analyzed the structural organization of mitotic spindle microtubules, chromosomes and centrosomes by electron microscopy after incubating HeLa cells for one cell cycle with 2 nM vinblastine. We found that mitotic block of HeLa cells by vinblastine was associated with alterations of the fine structure of the spindle that were subtle but profound in their apparent consequences. The cell cycle was blocked in a stage that resembled prometaphase or metaphase; chromosomes had not undergone anaphase segregation. Neither the structure of the microtubules nor the structure of the kinetochores was detectably altered by the drug. However, the number of microtubules attached to kinetochores was decreased significantly. In addition, the centrosomes were altered; the normal close association of mother and daughter centriole was lost, numerous membranous vesicles were found in the centrosomal region, and many centrioles exhibited abnormal ultrastructure and had microtubules coursing through their interiors. These findings are consistent with our previous results and indicate that inhibition of the polymerization dynamics of mitotic spindle microtubules and perhaps of centriole microtubules, rather than microtubule depolymerization, is responsible for the mitotic inhibition by vinblastine.

Effects of vinblastine, podophyllotoxin and nocodazole on mitotic spindles. Implications for the role of microtubule dynamics in mitosis

1992 ◽  
Vol 102 (3) ◽  
pp. 401-416 ◽  
Author(s):  
M.A. Jordan ◽  
D. Thrower ◽  
L. Wilson
Keyword(s):  
Hela Cells ◽  
Mitotic Arrest ◽  
Mitotic Spindles ◽  
Microtubule Depolymerization ◽  
Metaphase Chromosomes ◽  
Low Concentrations ◽  
Subtle Effect ◽  
Full Complement ◽  
Spindle Microtubules

Inhibition of mitosis by many drugs that bind to tubulin has been attributed to depolymerization of microtubules. However, we found previously that low concentrations of vinblastine and vincristine blocked mitosis in HeLa cells with little or no depolymerization of spindle microtubules, and spindles appeared morphologically normal or nearly normal. In the present study, we characterized the effects of vinblastine, podophyllotoxin and nocodazole over broad concentration ranges on mitotic spindle organization in HeLa cells. These three drugs are known to affect the dynamics of microtubule polymerization in vitro and to depolymerize microtubules in cells. We wanted to probe further whether mitotic inhibition by these drugs is brought about by a more subtle effect on the microtubules than net microtubule depolymerization. We compared the effects of vinblastine, podophyllotoxin and nocodazole on the organization of spindle microtubules, chromosomes and centrosomes, and on the total mass of microtubules. Spindle organization was examined by immunofluorescence microscopy, and microtubule polymer mass was assayed on isolated cytoskeletons by a quantitative enzyme-linked immunoadsorbence assay for tubulin. As the drug concentration was increased, the organization of mitotic spindles changed in the same way with all three drugs. The changes were associated with mitotic arrest, but were not necessarily accompanied by net microtubule depolymerization. With podophyllotoxin, mitotic arrest was accompanied by microtubule depolymerization. In contrast, with vinblastine and nocodazole, mitotic arrest occurred in the presence of a full complement of spindle microtubules. All three drugs induced a nearly identical rearrangement of spindle microtubules, an increasingly aberrant organization of metaphase chromosomes, and fragmentation of centrosomes. The data suggest that these anti-mitotic drugs block mitosis primarily by inhibiting the dynamics of spindle microtubules rather than by simply depolymerizing the microtubules.

The Xenopus protein kinase pEg2 associates with the centrosome in a cell cycle-dependent manner, binds to the spindle microtubules and is involved in bipolar mitotic spindle assembly

1998 ◽  
Vol 111 (5) ◽  
pp. 557-572 ◽  
Author(s):  
C. Roghi ◽  
R. Giet ◽  
R. Uzbekov ◽  
N. Morin ◽  
I. Chartrain ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Mitotic Spindle ◽  
Cultured Cells ◽  
Dependent Manner ◽  
Egg Extracts ◽  
Pericentriolar Material ◽  
Spindle Microtubules ◽  
Cycle Dependent

By differential screening of a Xenopus laevis egg cDNA library, we have isolated a 2,111 bp cDNA which corresponds to a maternal mRNA specifically deadenylated after fertilisation. This cDNA, called Eg2, encodes a 407 amino acid protein kinase. The pEg2 sequence shows significant identity with members of a new protein kinase sub-family which includes Aurora from Drosophila and Ipl1 (increase in ploidy-1) from budding yeast, enzymes involved in centrosome migration and chromosome segregation, respectively. A single 46 kDa polypeptide, which corresponds to the deduced molecular mass of pEg2, is immunodetected in Xenopus oocyte and egg extracts, as well as in lysates of Xenopus XL2 cultured cells. In XL2 cells, pEg2 is immunodetected only in S, G2 and M phases of the cell cycle, where it always localises to the centrosomal region of the cell. In addition, pEg2 ‘invades’ the microtubules at the poles of the mitotic spindle in metaphase and anaphase. Immunoelectron microscopy experiments show that pEg2 is located precisely around the pericentriolar material in prophase and on the spindle microtubules in anaphase. We also demonstrate that pEg2 binds directly to taxol stabilised microtubules in vitro. In addition, we show that the presence of microtubules during mitosis is not necessary for an association between pEg2 and the centrosome. Finally we show that a catalytically inactive pEg2 kinase stops the assembly of bipolar mitotic spindles in Xenopus egg extracts.

The role of gamma-tubulin in mitotic spindle formation and cell cycle progression in Aspergillus nidulans

1997 ◽  
Vol 110 (5) ◽  
pp. 623-633 ◽  
Author(s):  
M.A. Martin ◽  
S.A. Osmani ◽  
B.R. Oakley
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
Cell Cycle Progression ◽  
Spindle Pole ◽  
Microtubule Assembly ◽  
Cytoplasmic Microtubule ◽  
Cycle Progression ◽  
Spindle Microtubules ◽  
Gamma Tubulin

gamma-Tubulin has been hypothesized to be essential for the nucleation of the assembly of mitotic spindle microtubules, but some recent results suggest that this may not be the case. To clarify the role of gamma-tubulin in microtubule assembly and cell-cycle progression, we have developed a novel variation of the gene disruption/heterokaryon rescue technique of Aspergillus nidulans. We have used temperature-sensitive cell-cycle mutations to synchronize germlings carrying a gamma-tubulin disruption and observe the phenotypes caused by the disruption in the first cell cycle after germination. Our results indicate that gamma-tubulin is absolutely required for the assembly of mitotic spindle microtubules, a finding that supports the hypothesis that gamma-tubulin is involved in spindle microtubule nucleation. In the absence of functional gamma-tubulin, nuclei are blocked with condensed chromosomes for about the length of one cell cycle before chromatin decondenses without nuclear division. Our results indicate that gamma-tubulin is not essential for progression from G1 to G2, for entry into mitosis nor for spindle pole body replication. It is also not required for reactivity of spindle pole bodies with the MPM-2 antibody which recognizes a phosphoepitope important to mitotic spindle formation. Finally, it does not appear to be absolutely required for cytoplasmic microtubule assembly but may play a role in the formation of normal cytoplasmic microtubule arrays.

scholarly journals Centrioles in the cell cycle. I. Epithelial cells.

1982 ◽  
Vol 93 (3) ◽  
pp. 938-949 ◽  
Author(s):  
I A Vorobjev ◽  
Chentsov YuS
Keyword(s):  
Cell Cycle ◽  
Mitotic Cycle ◽  
Spindle Pole ◽  
Pig Kidney ◽  
Spindle Poles ◽  
Mother And Daughter ◽  
Mother Centriole ◽  
Spindle Microtubules ◽  
S Period ◽  
Number Of Cells

A study was made of the structure of the centrosome in the cell cycle in a nonsynchronous culture of pig kidney embryo (PE) cells. In the spindle pole of the metaphase cell there are two mutually perpendicular centrioles (mother and daughter) which differ in their ultrastructure. An electron-dense halo, which surrounds only the mother centriole and is the site where spindle microtubules converge, disappears at the end of telophase. In metaphase and anaphase, the mother centriole is situated perpendicular to the spindle axis. At the beginning of the G1 period, pericentriolar satellites are formed on the mother centriole with microtubules attached to them; the two centrioles diverge. The structures of the two centrioles differ throughout interphase; the mother centriole has appendages, the daughter does not. Replication of the centrioles occurs approximately in the middle of the S period. The structure of the procentrioles differs sharply from that of the mature centriole. Elongation of procentrioles is completed in prometaphase, and their structure undergoes a number of successive changes. In the G2 period, pericentriolar satellites disappear and some time later a fibrillar halo is formed on both mother centrioles, i.e., spindle poles begin to form. In the cells that have left the mitotic cycle (G0 period), replication of centrioles does not take place; in many cells, a cilium is formed on the mother centriole. In a small number of cells a cilium is formed in the S and G2 periods, but unlike the cilium in the G0 period it does not reach the surface of the cell. In all cases, it locates on the centriole with appendages. At the beginning of the G1 period, during the G2 period, and in nonciliated cells in the G0 period, one of the centrioles is situated perpendicular to the substrate. On the whole, it takes a mature centriole a cycle and a half to form in PE cells.

scholarly journals Cell cycle regulation of tubulin RNA level, tubulin protein synthesis, and assembly of microtubules in Physarum.

1984 ◽  
Vol 99 (1) ◽  
pp. 155-165 ◽  
Author(s):  
T Schedl ◽  
T G Burland ◽  
K Gull ◽  
W F Dove
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
Microscopic Analysis ◽  
Nucleic Acid Hybridization ◽  
Electron Microscopic ◽  
Two Dimensional Gel Electrophoresis ◽  
Spindle Microtubules ◽  
Beta 2

The temporal relationship between tubulin expression and the assembly of the mitotic spindle microtubules has been investigated during the naturally synchronous cell cycle of the Physarum plasmodium. The cell cycle behavior of the tubulin isoforms was examined by two-dimensional gel electrophoresis of proteins labeled in vivo and by translation of RNA in vitro. alpha 1-, alpha 2-, beta 1-, and beta 2-tubulin synthesis increases coordinately until metaphase, and then falls, with beta 2 falling more rapidly than beta 1. Nucleic acid hybridization demonstrated that alpha- and beta-tubulin RNAs accumulate coordinately during G2, peaking at metaphase. Quantitative analysis demonstrated that alpha-tubulin RNA increases with apparent exponential kinetics, peaking with an increase over the basal level of greater than 40-fold. After metaphase, tubulin RNA levels fall exponentially, with a short half-life (19 min). Electron microscopic analysis of the plasmodium showed that the accumulation of tubulin RNA begins long before the polymerization of mitotic spindle microtubules. By contrast, the decay of tubulin RNA after metaphase coincides with the depolymerization of the spindle microtubules.

scholarly journals Binding of E-MAP-115 to microtubules is regulated by cell cycle-dependent phosphorylation.

1995 ◽  
Vol 131 (4) ◽  
pp. 1015-1024 ◽  
Author(s):  
D Masson ◽  
T E Kreis
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Mitotic Spindle ◽  
Biochemical Characterization ◽  
Dynamic Properties ◽  
Cell Polarization ◽  
Early Prophase ◽  
Late Prophase ◽  
Mitotic Cells

Expression levels of E-MAP-115, a microtubule-associated protein that stabilizes microtubules, increase with epithelial cell polarization and differentiation (Masson and Kreis, 1993). Although polarizing cells contain significant amounts of this protein, they can still divide and thus all stabilized microtubules must disassemble at the onset of mitosis to allow formation of the dynamic mitotic spindle. We show here that binding of E-MAP-115 to microtubules is regulated by phosphorylation during the cell cycle. Immunolabeling of HeLa cells for E-MAP-115 indicates that the protein is absent from microtubules during early prophase and progressively reassociates with microtubules after late prophase. A fraction of E-MAP-115 from HeLa cells released from a block at the G1/S boundary runs with higher apparent molecular weight on SDS-PAGE, with a peak correlating with the maximal number of cells in early stages of mitosis. E-MAP-115 from nocodazole-arrested mitotic cells, which can be obtained in larger amounts, displays identical modifications and was used for further biochemical characterization. The level of incorporation of 32P into mitotic E-MAP-115 is about 15-fold higher than into the interphase protein. Specific threonine phosphorylation occurs in mitosis, and the amount of phosphate associated with serine also increases. Hyperphosphorylated E-MAP-115 from mitotic cells cannot bind stably to microtubules in vitro. These results suggest that phosphorylation of E-MAP-115 is a prerequisite for increasing the dynamic properties of the interphase microtubules which leads to the assembly of the mitotic spindle at the onset of mitosis. Microtubule-associated proteins are thus most likely key targets for kinases which control changes in microtubule dynamic properties at the G2- to M-phase transition.

scholarly journals Human Survivin Is a Kinetochore-Associated Passenger Protein

2000 ◽  
Vol 151 (7) ◽  
pp. 1575-1582 ◽  
Author(s):  
Dimitrios A. Skoufias ◽  
Cristiana Mollinari ◽  
Françoise B. Lacroix ◽  
Robert L. Margolis
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Mitotic Spindle ◽  
Deletion Mutant ◽  
Microtubule Assembly ◽  
Inhibitor Of Apoptosis ◽  
Nih3t3 Cells ◽  
Cell Cleavage ◽  
Spindle Midzone ◽  
Passenger Protein

Survivin, a dimeric baculovirus inhibitor of apoptosis repeat (BIR) motif protein that is principally expressed in G2 and mitosis, has been associated with protection against apoptosis of cells that exit mitosis aberrantly. Mammalian survivin has been reported to associate with centrosomes and with the mitotic spindle. We have expressed a human hemagglutinin-tagged survivin plasmid to determine its localization, and find instead that it clearly acts as a passenger protein. In HeLa cells, survivin first associates with the kinetochores, and then translocates to the spindle midzone during anaphase and, finally, to the midbody during cell cleavage. Its localization is similar to that of TD-60, a known passenger protein. Both a point mutation in the baculovirus IAP repeat motif (C84A) and a COOH-terminal deletion mutant (Δ106) of survivin fail to localize to either kinetochores or midbodies, but neither interferes with cell cleavage. The interphase localization of survivin is cell cycle regulated since in permanently transfected NIH3T3 cells it is excluded from the nuclei until G2, where it localizes with centromeres. Survivin remains associated with mitotic kinetochores when microtubule assembly is disrupted and its localization is thus independent of microtubules. We conclude that human survivin is positioned to have an important function in the mechanism of cell cleavage.

Procentriole microtubules as drivers of centriole reduplication

2020 ◽  
Author(s):  
Alejandra Vasquez-Limeta ◽  
Catherine Sullenberger ◽  
Dong Kong ◽  
Kimberly Lukasik ◽  
Anil Shukla ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Close Association ◽  
Cellular Transformation ◽  
S Phase ◽  
Ultrastructural Changes ◽  
List Type ◽  
Maturation Process ◽  
Centriole Duplication ◽  
Mother Centriole ◽  
G2 Phase

ABSTRACTCentriole reduplication leads to the formation of supernumerary centrosomes, which promote cellular transformation, invasion and are a hallmark of tumors. A close association between a mother centriole and a procentriole (engagement), established during centriole duplication, intrinsically blocks reduplication. Premature loss of centriole association predisposes centrioles for reduplication and occurs during various types of cell cycle arrests in the presence of high Polo-like kinase 1 activity. Here we use nano-scale imaging and biochemistry to reveal the processes leading to the loss of centriole association and reduplication. We discover that centriole reduplication is driven by events occurring on procentriole microtubule walls. These events are mechanistically different from mitotic centriole separation driven by Pericentrin and Separase but are similar to the physiological process of centriole distancing occurring in unperturbed cycling G2 cells. We propose a concept in which centriole reduplication is a consequence of hijacked and amplified centriole maturation process.HighlightsSeparase-mediated Pericentrin reorganization is not required for centriole distancing and reduplication in interphase.Expression of active Plk1 in S phase leads to centrosomal ultrastructural changes resembling G2 phase.Procentrioles without microtubule walls cannot disengage.Centriole distancing is intrinsically regulated by the events occurring on procentriole microtubules.

scholarly journals Nuclear phosphatidylinositols decrease during S-phase of the cell cycle in HeLa cells.

1994 ◽  
Vol 269 (11) ◽  
pp. 7847-7850
Author(s):  
J.D. York ◽  
P.W. Majerus
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
S Phase
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