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Theoretical Biology & Medical Modelling Feb 2014Nanoscale electrostatic microtubule disassembly forces between positively charged molecules in kinetochores and negative charges on plus ends of microtubules have been...
Nanoscale electrostatic microtubule disassembly forces between positively charged molecules in kinetochores and negative charges on plus ends of microtubules have been implicated in poleward chromosome motions and may also contribute to antipoleward chromosome movements. We propose that chromosome congression can be understood in terms of antipoleward nanoscale electrostatic microtubule assembly forces between negatively charged microtubule plus ends and like-charged chromosome arms, acting in conjunction with poleward microtubule disassembly forces. Several other aspects of post-attachment prometaphase chromosome motions, as well as metaphase oscillations, are consistently explained within this framework.
Topics: Chromosomes; Nanotechnology; Static Electricity
PubMed: 24564840
DOI: 10.1186/1742-4682-11-12 -
Molecular Cancer Therapeutics Apr 2007Diallyl trisulfide (DATS), a cancer chemopreventive constituent of garlic, inhibits growth of cancer cells by interfering with cell cycle progression, but the mechanism...
Activation of a novel ataxia-telangiectasia mutated and Rad3 related/checkpoint kinase 1-dependent prometaphase checkpoint in cancer cells by diallyl trisulfide, a promising cancer chemopreventive constituent of processed garlic.
Diallyl trisulfide (DATS), a cancer chemopreventive constituent of garlic, inhibits growth of cancer cells by interfering with cell cycle progression, but the mechanism is not fully understood. Here, we show the existence of a novel ataxia-telangiectasia mutated and Rad3 related (ATR)/checkpoint kinase 1 (Chk1)-dependent checkpoint partially responsible for DATS-mediated prometaphase arrest in cancer cells, which is different from the recently described gamma irradiation-induced mitotic exit checkpoint. The PC-3 human prostate cancer cells synchronized in prometaphase by nocodazole treatment and released to DATS-containing medium remained arrested in prometaphase, whereas the cells released to normal medium exited mitosis and resumed cell cycle. The mitotic arrest was maintained even after 4 h of culture of DATS-treated cells (4-h treatment) in drug-free medium. The DATS-arrested mitotic cells exhibited accumulation of anaphase-promoting complex/cyclosome (APC/C) substrates cyclin A and cyclin B1 and hyperphosphorylation of securin, which was accompanied by increased phosphorylation of the APC/C regulatory subunits Cdc20 and Cdh1. The DATS-mediated accumulation of cyclin B1 and hyperphosphorylation of securin, Cdc20, and Cdh1 were partially but markedly attenuated by knockdown of Chk1 or ATR protein. The U2OS osteosarcoma cells expressing doxycycline-inducible kinase dead ATR were significantly more resistant not only to DATS-mediated prometaphase arrest but also to the accumulation of cyclin B1 and hyperphosphorylation of securin, Cdc20, and Cdh1 compared with cells expressing wild-type ATR. However, securin protein knockdown failed to rescue cells from DATS-induced prometaphase arrest. In conclusion, the present study describes a novel signaling pathway involving ATR/Chk1 in the regulation of DATS-induced prometaphase arrest.
Topics: Allyl Compounds; Anaphase-Promoting Complex-Cyclosome; Antineoplastic Agents; Ataxia Telangiectasia Mutated Proteins; Cdc20 Proteins; Cell Cycle Proteins; Cell Line, Tumor; Checkpoint Kinase 1; Chemoprevention; Dose-Response Relationship, Drug; Enzyme Activation; Garlic; Humans; Kinetics; Models, Biological; Neoplasm Proteins; Neoplasms; Phosphorylation; Prometaphase; Protein Kinases; Protein Serine-Threonine Kinases; Securin; Sulfides; Time Factors; Ubiquitin-Protein Ligase Complexes
PubMed: 17406033
DOI: 10.1158/1535-7163.MCT-06-0477 -
The Journal of Cell Biology Aug 2000We have investigated the intracellular roles of an Xklp2-related kinesin motor, KRP(180), in positioning spindle poles during early sea urchin embryonic cell division...
We have investigated the intracellular roles of an Xklp2-related kinesin motor, KRP(180), in positioning spindle poles during early sea urchin embryonic cell division using quantitative, real-time analysis. Immunolocalization reveals that KRP(180) concentrates on microtubules in the central spindle, but is absent from centrosomes. Microinjection of inhibitory antibodies and dominant negative constructs suggest that KRP(180) is not required for the initial separation of spindle poles, but instead functions to transiently position spindle poles specifically during prometaphase.
Topics: Amino Acid Sequence; Animals; Calcium-Binding Proteins; Cell Cycle Proteins; Dimerization; Embryo, Nonmammalian; Fluorescent Antibody Technique; Kinesins; Metaphase; Microtubule-Associated Proteins; Models, Biological; Molecular Motor Proteins; Molecular Sequence Data; Muscle Proteins; Sea Urchins; Sequence Homology, Amino Acid; Spindle Apparatus; Xenopus Proteins
PubMed: 10931863
DOI: 10.1083/jcb.150.3.499 -
The Journal of Heredity 1987R-banded prometaphase karyotypes of the goat are presented using both fluorescent and light staining techniques. A model for the standardization of the R-banded...
R-banded prometaphase karyotypes of the goat are presented using both fluorescent and light staining techniques. A model for the standardization of the R-banded prometaphase goat karyotype is suggested.
Topics: Animals; Cells, Cultured; Chromosome Banding; Chromosomes; DNA Replication; Female; Goats; Karyotyping; Male; Metaphase
PubMed: 3624843
DOI: 10.1093/oxfordjournals.jhered.a110371 -
Journal of Medical Genetics Dec 1991A single lymphocyte culture system is described which produces both reliable fragile X expression and elongated chromosomes for prometaphase analysis. This system, which...
A single lymphocyte culture system is described which produces both reliable fragile X expression and elongated chromosomes for prometaphase analysis. This system, which is based on that described by Wheater and Roberts in 1987, involves the deoxycytidine release of a thymidine block. Eight fragile X positive subjects had an average expression level of 26%, with a range of 12% to 45%, using the thymidine/deoxycytidine protocol. This was comparable to the levels obtained in parallel cultures treated with thymidine alone or fluorodeoxyuridine.
Topics: Adolescent; Adult; Cells, Cultured; Child; Child, Preschool; Chromosome Fragility; Deoxycytidine; Female; Fragile X Syndrome; Gene Expression; Humans; Lymphocytes; Male; Metaphase; Middle Aged; Thymidine; X Chromosome
PubMed: 1757959
DOI: 10.1136/jmg.28.12.837 -
American Journal of Human Genetics Oct 1986Controversy continues to exist concerning the proportion of individuals with Prader-Willi syndrome who have a chromosome 15 deletion and concerning the reliability with...
Controversy continues to exist concerning the proportion of individuals with Prader-Willi syndrome who have a chromosome 15 deletion and concerning the reliability with which a cytogenetic service laboratory can accurately perform the appropriate analysis. Blind prometaphase cytogenetic study of 13 individuals from a Prader-Willi syndrome clinic and seven controls has revealed that approximately 70% of accurately diagnosed clinically typical patients with this disorder have an evident deletion of at least 15q12. Blind analysis of panels of chromosome 15 pairs from all cases in this study by the directors of four independent cytogenetic service laboratories demonstrated substantial interobserver consistency in interpretation of results. The possibility of euploid mosaicism for del 15q was investigated, but remains unresolved.
Topics: Adolescent; Adult; Child; Chromosome Deletion; Chromosomes, Human, Pair 15; Female; Genetic Markers; Humans; Karyotyping; Lymphocytes; Male; Metaphase; Prader-Willi Syndrome
PubMed: 3464201
DOI: No ID Found -
Journal of Cellular Physiology Nov 2002Mitotic cells show a tenfold increase in immunoreactive P2P-R protein. During mitosis, the distribution of P2P-R protein also changes from a primary nucleolar...
Mitotic cells show a tenfold increase in immunoreactive P2P-R protein. During mitosis, the distribution of P2P-R protein also changes from a primary nucleolar localization in interphase cells to the periphery of chromosome in mitotic cells. These findings suggest that P2P-R might serve a functional role in mitosis. To test this possibility, human Saos2 cells were stably transfected with P2P-R DNA constructs and the biological effects of P2P-R overexpression were evaluated. Overexpression of near full-length P2P-R was found to have paradoxical effects on the relationship between proliferation and mitosis in the nine Saos2 cell clones that were studied. A significant repression in the population doubling rates was observed in all nine clones even though a significant increase in the frequency of easily detached cells with a mitotic morphology was apparent. Flow cytometric analysis confirmed that greater than two thirds of the cells with a mitotic morphology had a 4n DNA content. Confocal microscopy further established that 85% of the mitotic cell population had prometaphase characteristics suggesting that P2P-R overexpression restricts mitotic progression at prometaphase. Many cells with a mitotic morphology also showed signs of apoptosis with prominent cell surface blebs. Confocal microscopy confirmed that 25-40% of such mitotic cells were apoptotic with chromosomal abnormalities and cell surface blebbing. In association with mitotic apoptosis, P2P-R protein appears to dissociate from the periphery of chromosomes and localize in the cytoplasm and in cell surface blebs. The presence of P2P-R in cell surface blebs was confirmed by analysis of highly enriched populations of apoptotic cell surface blebs wherein Western blotting documented the presence of 250 kDa P2P-R. These results therefore suggest that P2P-R overexpression promotes both prometaphase arrest in mitosis and mitotic apoptosis.
Topics: 3T3 Cells; Amino Acid Sequence; Animals; Antibodies, Monoclonal; Apoptosis; Carrier Proteins; Cell Line; Cell Membrane; Cell Nucleolus; Chromosome Aberrations; Clone Cells; Humans; Interphase; Metaphase; Mice; Mitosis; Ploidies; RNA-Binding Proteins; Transfection
PubMed: 12384997
DOI: 10.1002/jcp.10163 -
Cell Cycle (Georgetown, Tex.) Feb 2006Precisely timed ubiquitin-mediated proteolysis of mitotic regulators by the anaphase-promoting complex (APC) governs the orderly passage of cells through mitosis. The...
Precisely timed ubiquitin-mediated proteolysis of mitotic regulators by the anaphase-promoting complex (APC) governs the orderly passage of cells through mitosis. The established view is that Cdc20-activated APC (APC(Cdc20)) mediates the destruction of cyclin B and securin at the metaphase/anaphase transition, and that Cdh1-activated APC (APC(Cdh1)) has no role in this process. We recently reported that securin, but not cyclin B, is prematurely targeted for destruction by the APC in mutant mice that have low levels of the nuclear transport factors Rae1 and Nup98. We found that Rae1 and Nup98 assemble into a complex with APC(Cdh1) in prometaphase and act to delay APC(Cdh1)-mediated ubiquitination of securin until the metaphase/anaphase transition. Here we show that Rae1 and Nup98 not only form a complex with APC(Cdh1) in prometaphase but also with securin. This finding suggests that the Rae1-Nup98 complex does not inhibit early destruction of securin by preventing APC(Cdh1) from binding to securin, but by preventing ubiquitination of APC(Cdh1)-bound securin. We propose that the formation of APC(Cdh1)-securin complexes in prometaphase primes the cell for rapid securin degradation after release of the inhibitory Rae1-Nup98 complex at the metaphase/anaphase transition. We further report here that mutant mice with low levels of the Rae1-Nup98 complex are not prone to develop spontaneous tumors, despite massive aneuploidy. However, Rae1/Nup98 mutant mice are significantly more susceptible to DMBA-induced lung tumors than wild-type mice, indicating that combined Rae1/ Nup98 haplo-insufficiency does promote tumorigenesis when certain cancer-critical genes are also mutated.
Topics: Anaphase; Anaphase-Promoting Complex-Cyclosome; Aneuploidy; Animals; Carrier Proteins; Metaphase; Mice; Neoplasms; Nuclear Matrix-Associated Proteins; Nuclear Pore Complex Proteins; Nucleocytoplasmic Transport Proteins; Prometaphase; Protein Binding; Securin; Ubiquitin-Protein Ligase Complexes
PubMed: 16479161
DOI: 10.4161/cc.5.4.2483 -
Scientific Reports Apr 2018A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Author Correction: Lateral attachment of kinetochores to microtubules is enriched in prometaphase rosette and facilitates chromosome alignment and bi-orientation establishment.
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
PubMed: 29712957
DOI: 10.1038/s41598-018-25175-4 -
PloS One 2013Histone deacetylase inhibitors (HDACIs) have potent anti-cancer activity in a variety of cancer models. Understanding the molecular mechanisms involved in the...
Histone deacetylase inhibitors (HDACIs) have potent anti-cancer activity in a variety of cancer models. Understanding the molecular mechanisms involved in the therapeutic responsiveness of HDACI is needed before its clinical application. This study aimed to determine if a potent HDACI, LBH589 (Panobinostat), had differential therapeutic responsiveness towards LNCaP and PC-3 prostate cancer (PCa) cells. The former showed prometaphase arrest with subsequent apoptosis upon LBH589 treatment, while the latter was less sensitive and had late G2 arrest. The LBH589 treatment down-regulated HDAC6 and sustained ERK activation, and contributed to prometaphase arrest. Mechanistically, LBH589 inhibited HDAC6 activity, caused its dissociation from protein phosphatase PP1α, and increased 14-3-3ζ acetylation. Acetylated 14-3-3ζ released its mask effect on serine 259 of c-Raf and serine 216 of Cdc25C subsequent to de-phosphorylation by PP1α, which contributed to ERK activation. Enhanced ERK activity by LBH589 further down-regulated HDAC6 protein levels and sustained ERK activation by free-forward regulation. The sustained Cdc25C and ERK activation resulted in early M-phase (prometaphase) arrest and subsequent apoptosis in the most sensitive LNCaP cells but not in PC-3 cells. This study provides pre-clinical evidence that HDAC6 may serve as a sensitive therapeutic target in the treatment of prostate cancer with HDACI LBH589 for clinical translation. This study also posits a novel mechanism of HDAC6 participation in regulating the c-Raf-PP1-ERK signaling pathway and contributing to M phase cell-cycle transition.
Topics: 14-3-3 Proteins; Acetylation; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; G2 Phase Cell Cycle Checkpoints; Histone Deacetylase 6; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Indoles; M Phase Cell Cycle Checkpoints; Male; Panobinostat; Prostatic Neoplasms; Protein Phosphatase 1; Proto-Oncogene Proteins c-raf; Signal Transduction; cdc25 Phosphatases
PubMed: 24023871
DOI: 10.1371/journal.pone.0073401