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Cells Jul 2022Centrosome-containing cells assemble their spindles exploiting three main classes of microtubules (MTs): MTs nucleated by the centrosomes, MTs generated near the...
Centrosome-containing cells assemble their spindles exploiting three main classes of microtubules (MTs): MTs nucleated by the centrosomes, MTs generated near the chromosomes/kinetochores, and MTs nucleated within the spindle by the augmin-dependent pathway. Mammalian and cells lacking the centrosomes generate MTs at kinetochores and eventually form functional bipolar spindles. However, the mechanisms underlying kinetochore-driven MT formation are poorly understood. One of the ways to elucidate these mechanisms is the analysis of spindle reassembly following MT depolymerization. Here, we used an RNA interference (RNAi)-based reverse genetics approach to dissect the process of kinetochore-driven MT regrowth (KDMTR) after colcemid-induced MT depolymerization. This MT depolymerization procedure allows a clear assessment of KDMTR, as colcemid disrupts centrosome-driven MT regrowth but not KDMTR. We examined KDMTR in normal S2 cells and in S2 cells subjected to RNAi against conserved genes involved in mitotic spindle assembly: // (), (), (), (), (), (), (), and (). RNAi-mediated depletion of Mast/Orbit, Mei-38, Mars, Dgt6, and Eb1 caused a significant delay in KDMTR, while loss of Patronin had a milder negative effect on this process. In contrast, Asp or Klp10A deficiency increased the rate of KDMTR. These results coupled with the analysis of GFP-tagged proteins (Mast/Orbit, Mei-38, Mars, Eb1, Patronin, and Asp) localization during KDMTR suggested a model for kinetochore-dependent spindle reassembly. We propose that kinetochores capture the plus ends of MTs nucleated in their vicinity and that these MTs elongate at kinetochores through the action of Mast/Orbit. The Asp protein binds the MT minus ends since the beginning of KDMTR, preventing excessive and disorganized MT regrowth. Mei-38, Mars, Dgt6, Eb1, and Patronin positively regulate polymerization, bundling, and stabilization of regrowing MTs until a bipolar spindle is reformed.
Topics: Animals; Demecolcine; Drosophila; Drosophila Proteins; Kinesins; Kinetochores; Mammals; Microtubule-Associated Proteins; Microtubules; Mitosis; Spindle Apparatus
PubMed: 35883570
DOI: 10.3390/cells11142127 -
Foods (Basel, Switzerland) Apr 2020In this work, the phytochemical profile and the biological properties of (an unexplored Turkish cultivar belonging to Colchicaceae) have been comprehensively...
In this work, the phytochemical profile and the biological properties of (an unexplored Turkish cultivar belonging to Colchicaceae) have been comprehensively investigated for the first time. Herein, we focused on the evaluation of the in vitro antioxidant and enzyme inhibitory effects of flower, tuber, and leaf extracts, obtained using different extraction methods, namely maceration (both aqueous and methanolic), infusion, and Soxhlet. Besides, the complete phenolic and alkaloid untargeted metabolomic profiling of the different extracts was investigated. In this regard, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) allowed us to putatively annotate 285 compounds when considering the different matrix extracts, including mainly alkaloids, flavonoids, lignans, phenolic acids, and tyrosol equivalents. The most abundant polyphenols were flavonoids (119 compounds), while colchicine, demecolcine, and lumicolchicine isomers were some of the most widespread alkaloids in each extract analyzed. In addition, our findings showed that tuber extracts were a superior source of both total alkaloids and total polyphenols, being on average 2.89 and 10.41 mg/g, respectively. Multivariate statistics following metabolomics allowed for the detection of those compounds most affected by the different extraction methods. Overall, extracts showed a strong in vitro antioxidant capacity, in terms of cupric reducing antioxidant power (CUPRAC; on average 96.45 mg Trolox Equivalents (TE)/g) and ferric reducing antioxidant power (FRAP) reducing power (on average 66.86 mg TE/g). Interestingly, each methanolic extract analyzed (i.e., from tuber, leaf, and flower) was active against the tyrosinase in terms of inhibition, recording the higher values for methanolic macerated leaves (i.e., 125.78 mg kojic acid equivalent (KAE)/g). On the other hand, moderate inhibitory activities were observed against AChE and α-amylase. Strong correlations ( < 0.01) were also observed between the phytochemical profiles and the biological activities determined. Therefore, our findings highlighted, for the first time, the potential of extracts in food and pharmaceutical applications.
PubMed: 32276367
DOI: 10.3390/foods9040457 -
Reproduction, Nutrition, Development 2006The objective of this study was to investigate the possible effect of demecolcine, a microtubule-disrupting reagent, on induced enucleation (IE) of sheep meiotically...
The objective of this study was to investigate the possible effect of demecolcine, a microtubule-disrupting reagent, on induced enucleation (IE) of sheep meiotically maturing oocytes. Immunofluorescent staining with anti-tubulin antibodies was used to examine the spindle status of the oocytes. When the oocytes with intact germinal vesicles (GV) were cultured in the medium containing various concentrations of demecolcine (0.01 to 0.4 microg.mL-1) for 20 to 22 h, the spindle microtubule organization and first polar body (PB1) extrusion were inhibited by demecolcine in a dose-dependent manner. The highest IE rate (58.1%) was from the treatment with 0.04 microg.mL-1 demecolcine. Demecolcine treatment applied after germinal vesicle breakdown (GVBD) or at metaphase (M) yielded a PB1 extrusion rate and IE efficiency similar to the treatment applied at the onset of maturation. Analysis by immunofluorescence showed that both nonspindle microtubules and spindle microtubules were significantly disorganized by demecolcine. Combination treatment with demecolcine and cycloheximide (CHX) or 6-dimethylaminopurine (6-DMAP) led to single pronuclear formation rather than PB1 extrusion. When demecolcine-treated oocytes were transferred into demecolcine-free medium, the ability to extrude PB1 was quickly restored and a 72.1% IE rate was obtained following such treatment. These results demonstrate that demecolcine can be used as a potential reagent for induced enucleation of sheep meiotically maturing oocytes and may greatly facilitate research in nuclear transfer.
Topics: Animals; Cell Nucleus; Cells, Cultured; Demecolcine; Dose-Response Relationship, Drug; Embryo, Mammalian; Female; Immunohistochemistry; Meiosis; Microtubules; Nuclear Transfer Techniques; Oocytes; Sheep
PubMed: 16597428
DOI: 10.1051/rnd:2006002 -
Scientific Reports May 2021The knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in...
The knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell's cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.
Topics: Actins; Biomechanical Phenomena; Breast Neoplasms; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Demecolcine; Female; Fibronectins; Heterocyclic Compounds, 4 or More Rings; Humans; MCF-7 Cells; Magnetic Iron Oxide Nanoparticles; Microtubules; Temperature; Thiazolidines
PubMed: 34031462
DOI: 10.1038/s41598-021-90173-y -
The Journal of Reproduction and... Apr 2008The present study was carried out to examine whether demecolcine and sucrose affect the formation of a cytoplasmic protrusion containing chromosomes in pig oocytes...
The present study was carried out to examine whether demecolcine and sucrose affect the formation of a cytoplasmic protrusion containing chromosomes in pig oocytes independently or in combination. In the presence of 20 mM sucrose, the rates of oocytes with a cytoplasmic protrusion after culture for 60 min with 0.2-1.0 microg/ml demecolcine were significantly higher than those with 0.01-0.05 microg/ml demecolcine. When oocytes were cultured for 15 min in the presence of 0.2 microg/ml demecolcine and 20 mM sucrose, 35.1% of them extruded a cytoplasmic protrusion; this rate was significantly lower than those of oocytes cultured for 30-90 min. In the presence of 0.2 microg/ml demecolcine, significantly fewer oocytes extruded a cytoplasmic protrusion after culture for 30 min with 160 mM sucrose than with 0-80 mM sucrose. Significantly more oocytes extruded a cytoplasmic protrusion after culture for 30 min with 0.2 microg/ml demecolcine than without it, regardless of the presence or absence of 20 mM sucrose. In 88.9-100% of the oocytes, the cytoplasmic protrusions contained chromosomes with no significant differences among the different concentrations of demecolcine and sucrose and among the different treatment times. The results of the present study show that the cytoplasmic protrusion containing chromosomes in the pig oocyte is attributable to demecolcine, but sucrose does not affect its formation.
Topics: Animals; Chromosomes; Cloning, Organism; Cytoplasm; Demecolcine; Embryo Transfer; Female; Models, Biological; Nuclear Transfer Techniques; Oocytes; Sucrose; Swine; Time Factors; Tubulin Modulators
PubMed: 18239352
DOI: 10.1262/jrd.19142 -
BMC Biology Dec 2021The integrity of microtubule filament networks is essential for the roles in diverse cellular functions, and disruption of its structure or dynamics has been explored as...
BACKGROUND
The integrity of microtubule filament networks is essential for the roles in diverse cellular functions, and disruption of its structure or dynamics has been explored as a therapeutic approach to tackle diseases such as cancer. Microtubule-interacting drugs, sometimes referred to as antimitotics, are used in cancer therapy to target and disrupt microtubules. However, due to associated side effects on healthy cells, there is a need to develop safer drug regimens that still retain clinical efficacy. Currently, many questions remain open regarding the extent of effects on cellular physiology of microtubule-interacting drugs at clinically relevant and low doses. Here, we use super-resolution microscopies (single-molecule localization and optical fluctuation based) to reveal the initial microtubule dysfunctions caused by nanomolar concentrations of colcemid.
RESULTS
We identify previously undetected microtubule (MT) damage caused by clinically relevant doses of colcemid. Short exposure to 30-80 nM colcemid results in aberrant microtubule curvature, with a trend of increased curvature associated to increased doses, and curvatures greater than 2 rad/μm, a value associated with MT breakage. Microtubule fragmentation was detected upon treatment with ≥ 100 nM colcemid. Remarkably, lower doses (< 20 nM after 5 h) led to subtle but significant microtubule architecture remodelling characterized by increased curvature and suppression of microtubule dynamics.
CONCLUSIONS
Our results support the emerging hypothesis that microtubule-interacting drugs induce non-mitotic effects in cells, and establish a multi-modal imaging assay for detecting and measuring nanoscale microtubule dysfunction. The sub-diffraction visualization of these less severe precursor perturbations compared to the established antimitotic effects of microtubule-interacting drugs offers potential for improved understanding and design of anticancer agents.
Topics: Cytoskeleton; Demecolcine; Microscopy, Fluorescence; Microtubules
PubMed: 34895240
DOI: 10.1186/s12915-021-01164-4 -
BioEssays : News and Reviews in... Sep 2012Recent studies indicate that mammalian chromosomes contain discrete cis-acting loci that control replication timing, mitotic condensation, and stability of entire... (Review)
Review
Recent studies indicate that mammalian chromosomes contain discrete cis-acting loci that control replication timing, mitotic condensation, and stability of entire chromosomes. Disruption of the large non-coding RNA gene ASAR6 results in late replication, an under-condensed appearance during mitosis, and structural instability of human chromosome 6. Similarly, disruption of the mouse Xist gene in adult somatic cells results in a late replication and instability phenotype on the X chromosome. ASAR6 shares many characteristics with Xist, including random mono-allelic expression and asynchronous replication timing. Additional "chromosome engineering" studies indicate that certain chromosome rearrangements affecting many different chromosomes display this abnormal replication and instability phenotype. These observations suggest that all mammalian chromosomes contain "inactivation/stability centers" that control proper replication, condensation, and stability of individual chromosomes. Therefore, mammalian chromosomes contain four types of cis-acting elements, origins, telomeres, centromeres, and "inactivation/stability centers", all functioning to ensure proper replication, condensation, segregation, and stability of individual chromosomes.
Topics: Animals; Aurora Kinases; Chromosomal Instability; Chromosomes; DNA Damage; DNA Replication Timing; Demecolcine; Humans; Mammals; Mitosis; Phenotype; Protein Serine-Threonine Kinases; Regulatory Sequences, Nucleic Acid; Replication Origin; X Chromosome Inactivation
PubMed: 22706734
DOI: 10.1002/bies.201200035 -
Cellular Reprogramming Dec 2013Despite its success in almost all farm and laboratory animals, somatic cell nuclear transfer (SCNT) is still a low-efficiency technique. In this investigation, we...
Despite its success in almost all farm and laboratory animals, somatic cell nuclear transfer (SCNT) is still a low-efficiency technique. In this investigation, we determined the impact of each enucleation step on oocyte viability (assessed by parthenogenetic activation): Hoechst (HO) staining, cytochalasin B, ultraviolet (UV) exposure, and demecolcine. Our data showed that of all the factors analyzed, UV exposure impaired oocyte development (cleavage, 59% for untreated oocytes vs. 8% UV exposed; blastocyst stage, 32% untreated vs. 0% UV exposed). A minor toxicity was detected following demecolcine treatment (cleavage, 62%; blastocyst stage, 13%). Next, we compared HO/UV (canonical) and demecolcine-assisted enucleation (DAE), with a straight removal of metaphase chromosomes without any chemical or physical aid (straight enucleation). DAE improved the preimplantation development of sheep cloned embryos compared to HO/UV enucleation (cleavage, 38% vs. 19%; blastocysts, 17% vs. 4%), yet straight enucleation resulted in the highest cleavage and blastocysts rates (61% and 30%, respectively). We concluded that: (1) UV exposure harms sheep oocyte and embryo development; (2) DAE may represent an alternative approach, especially for unskilled operators; and (3) straight enucleation remains, in our estimation, the most reliable and least harmful protocol for SCNT.
Topics: Animals; Blastocyst; Cloning, Organism; Culture Media; Demecolcine; Female; Oocytes; Sheep
PubMed: 24219576
DOI: 10.1089/cell.2013.0051 -
Cellular Physiology and Biochemistry :... 2014Our study aims to clarify the effects of demecolcine, alone or in combination with sucrose on bovine oocyte protrusion rate, MAPK1 protein level and c-mos gene...
AIMS
Our study aims to clarify the effects of demecolcine, alone or in combination with sucrose on bovine oocyte protrusion rate, MAPK1 protein level and c-mos gene expression level.
METHODS
The effects of the demecolcine concentration, treatment duration, and synergistic effects with sucrose solution on the rate of membrane protrusions of bovine oocytes were investigated. Using real-time fluorescent quantitative PCR, western blot analysis, and immunofluorescence assays, the expression of the maternal c-mos gene, the protein level of mitogen-activated protein kinase 1 (MAPK1), and the change in the localization of spindles and nuclei during the demecolcine treatment were analyzed in bovine oocytes.
RESULTS
Treatment of bovine oocytes with both demecolcine (0.6 μg/mL) and sucrose (0.05 M) for 1 h led to the highest rate of membrane protrusions, and synergistic effects were also observed. Real-time fluorescent quantitative PCR analysis revealed that the demecolcine treatment up-regulated the expression of the maternal c-mos gene. Western blot analysis indicated that the demecolcine treatment enhanced the protein level of MAPK1 in bovine oocytes. Immunofluorescence analysis indicated that the spindles and nuclei were localized at the place of the membrane protrusions.
CONCLUSIONS
The present results suggest that demecolcine might contribute to the activation of the Mos/MAPK pathway and affect spindle structure. These results provide a reference for more efficient generation of enucleated bovine oocytes.
Topics: Animals; Cattle; Cell Nucleus; Demecolcine; Gene Expression Regulation, Developmental; Mitogen-Activated Protein Kinase 1; Oocytes; Proto-Oncogene Proteins c-mos; Spindle Apparatus; Sucrose
PubMed: 25500918
DOI: 10.1159/000366393 -
PloS One 2014Demecolcine (DEM) treatment of oocytes induces formation of a membrane protrusion containing a mass of condensed maternal chromosomes, which can be removed with minimal...
Demecolcine (DEM) treatment of oocytes induces formation of a membrane protrusion containing a mass of condensed maternal chromosomes, which can be removed with minimal damage prior to somatic cell nuclear transfer (SCNT). However, the effect of this method on the distribution of maturation-promoting factor (MPF) in porcine oocytes has not been reported. Here, the level of MPF and the distribution of cyclin B1 were assessed in porcine oocytes following DEM treatment. In addition, the efficiencies of DEM-assisted and mechanical enucleation were compared, as were the development (in vitro and in vivo) of these oocytes following SCNT. MPF was uniformly distributed in oocytes that had been treated with 0.4 μg/ml DEM for 1 h. Immunofluorescence microscopy showed that in untreated oocytes, cyclin B1, the regulatory subunit of MPF, accumulated around the spindle, and was lowly detected in the cytoplasm. DEM treatment disrupted spindle microtubules, induced chromosome condensation, and reduced the level of cyclin B1 in the nuclear region. Cyclin B1 was uniformly distributed in DEM-treated oocytes and the level of MPF was increased. The potential of embryos generated from DEM-treated oocytes to develop in vivo was significantly greater than that of embryos generated from mechanically enucleated oocytes. This is the first study to report the effects of DEM-assisted enucleation of porcine oocytes on the distribution of cyclin B1. MPF in mature oocytes is important for the development of reconstructed embryos and for efficient SCNT.
Topics: Animals; Cyclin B1; Cytoplasm; Demecolcine; Ear; Embryo Transfer; Fibroblasts; Gene Expression Regulation, Developmental; Microscopy, Fluorescence; Microtubules; Nuclear Transfer Techniques; Oocytes; Spindle Apparatus; Swine; Swine, Miniature; Tubulin Modulators
PubMed: 24626152
DOI: 10.1371/journal.pone.0091483