To identify the component(s) involved in cell cycle control in the protozoan Giardia lamblia, cells arrested at the G1/S- or G2-phase by treatment with nocodazole and aphidicolin were prepared from the synchronized cell cultures. RNA-sequencing analysis of the 2 stages of Giardia cell cycle identified several cell cycle genes that were up-regulated at the G2-phase. Transcriptome analysis of cells in 2 distinct cell cycle stages of G. lamblia confirmed previously reported components of cell cycle (PcnA, cyclin B, and CDK) and identified additional cell cycle components (NEKs, Mad2, spindle pole protein, and CDC14A). This result indicates that the cell cycle machinery operates in this protozoan, one of the earliest diverging eukaryotic lineages.
Aphidicolin ; Cell Culture Techniques ; Cell Cycle ; Cell Cycle Checkpoints ; Cyclin B ; Gene Expression Profiling ; Genes, cdc ; Giardia lamblia ; Giardia ; Nocodazole ; Spindle Poles

Hyperhomocysteinemia (HHcy) accelerates atherosclerosis by increasing proliferation and stimulating cytokine secretion in T cells. However, whether homocysteine (Hcy)-mediated T cell activation is associated with metabolic reprogramming is unclear. Here, our in vivo and in vitro studies showed that Hcy-stimulated splenic T-cell activation in mice was accompanied by increased levels of mitochondrial reactive oxygen species (ROS) and calcium, mitochondrial mass and respiration. Inhibiting mitochondrial ROS production and calcium signals or blocking mitochondrial respiration largely blunted Hcy-induced T-cell interferon γ (IFN-γ) secretion and proliferation. Hcy also enhanced endoplasmic reticulum (ER) stress in T cells, and inhibition of ER stress with 4-phenylbutyric acid blocked Hcy-induced T-cell activation. Mechanistically, Hcy increased ER-mitochondria coupling, and uncoupling ER-mitochondria by the microtubule inhibitor nocodazole attenuated Hcy-stimulated mitochondrial reprogramming, IFN-γ secretion and proliferation in T cells, suggesting that juxtaposition of ER and mitochondria is required for Hcy-promoted mitochondrial function and T-cell activation. In conclusion, Hcy promotes T-cell activation by increasing ER-mitochondria coupling and regulating metabolic reprogramming.
Animals ; Calcium ; metabolism ; Cell Proliferation ; drug effects ; Cells, Cultured ; Endoplasmic Reticulum ; metabolism ; Endoplasmic Reticulum Stress ; drug effects ; Endoribonucleases ; metabolism ; Female ; Homocysteine ; toxicity ; Interferon-gamma ; analysis ; Metabolic Engineering ; Mice ; Mice, Inbred C57BL ; Mitochondria ; drug effects ; metabolism ; Nocodazole ; pharmacology ; Phenylbutyrates ; pharmacology ; Protein-Serine-Threonine Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Reactive Oxygen Species ; metabolism ; T-Lymphocytes ; cytology ; drug effects ; metabolism ; eIF-2 Kinase ; metabolism

OBJECTIVETo investigate the changes of drug sensitivity of spindle poison-induced polyploid tumor cells to chemotherapeutic agents and its possible mechanism.

METHODSNocodazole in a dose of 100 ng/ml was used to induce polyploidization in a breast cancer cell line MDA-MB-231 cells. The polyploid cells (T-MDA-MB-231) were sorted by flow cytometry. The morphological changes and proliferation of T-MDA-MB-231 cells were compared with that of MDA-MB-231 cells. The cell growth inhibition was assessed by MTT assay. The cells were treated with paclitaxel, docetaxel, vincristine, epirubicin, 5-Fu, VP16 and oxaliplatin, respectively. Those cells were labeled with annexin V-FITC/PI and analyzed by flow cytometry. Bcl-2 was knocked down in T-MDA-MB-231 cells using SiRNA and their growth inhibition was evaluated by MTT assay to evaluate the reversing effect of Bcl-2-silencing on drug resistance.

RESULTSThe polyploid T-MDA-MB-231 cells grew in vitro continuously and maintained constant DNA content. They had a larger cell size, and grew more slowly than MDA-MB-231 cells. The IC(50(s)) of T-MDA-MB-231 cells were significantly higher than that of the MDA-MB-231 cells: paclitaxel: (6.37 ± 0.07) vs. (2.05 ± 0.83) µmol/L; docetaxel: (32.98 ± 1.48) vs. (11.95 ± 0.98) µmol/L; vincristine: (35.28 ± 1.66) vs. (14.58 ± 0.94) µmol/L; oxaliplatin: (19.07 ± 0.45) vs. (9.75 ± 1.05) µmol/L; 5-Fu: (85.49 ± 3.21) vs. (31.35 ± 1.51) µmol/L; and epirubicin: (0.53 ± 0.06) vs. (0.15 ± 0.01) µmol/L, (all P < 0.05). The IC(50(s)) of VP16 in T-MDA-MB-231 cells was (2.85 ± 0.50)µmol/L, significantly lower than the (12.20 ± 1.55) µmol/L in MDA-MB-231 cells (P < 0.05), and that of T-MDA-MB-231 cells after Bcl-2-knocked down by siRNA was (19.59 ± 0.48) µmol/L, significantly higher than the (12.20 ± 1.55) µmol/L in the MDA-MB-231 cells (P < 0.05). The IC(50(s)) of docetaxel of T-MDA-MB-231 cells after Bcl-2-knocked down by siRNA was (21.52 ± 0.68) µmol/L, significantly decreased and lower than that before Bcl-2 silencing (32.98 ± 1.48) µmol/L.

CONCLUSIONSOur results indicate that polyploid tumor cells induced by spindle poison Nocodazole are more resistant to most of chemotherapeutic drugs. Downregulation of Bcl-2 increases the sensitivity of polyploid cells to docetaxel. The high expression of Bcl-2 may be one of the drug resistance mechanisms of polyploid tumor cells. The polyploid tumor cells are relatively sensitive to VP16, suggesting that VP16 might be an effective candidate drug for treatment of chemoresistant polyploid tumors.

Antineoplastic Agents ; pharmacology ; Antineoplastic Agents, Phytogenic ; pharmacology ; Apoptosis ; drug effects ; Breast Neoplasms ; genetics ; metabolism ; pathology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Down-Regulation ; Drug Resistance, Neoplasm ; Epirubicin ; pharmacology ; Etoposide ; pharmacology ; Female ; Fluorouracil ; pharmacology ; Gene Knockdown Techniques ; Humans ; Inhibitory Concentration 50 ; Nocodazole ; pharmacology ; Organoplatinum Compounds ; pharmacology ; Paclitaxel ; pharmacology ; Polyploidy ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; Taxoids ; pharmacology ; Vincristine ; pharmacology

Endochondral bone formation of the developing cranial base is a complex process. This mechanism requires precise orchestration of many cellular events and cartilage matrix metabolism, such as proliferation, becoming round in shape, termination of proliferation, hypertrophic size-increase, and finally programmed cell death. Active formation and degradation of cartilage matrix take place, in which microtubules are involved for intracellular events; bone apposition follows these events. However, the involvement of microtubules during these changes in the developing cranial base has not been identified yet. Thus, we investigated the involvement of microtubules in the regulation of endochondral bone formation during cranial base development. Using tubulin-binding drug nocodazole, we examined the effects of altering the structure and function of microtubules during in vivo organ culture of the mouse cranial base. Cultured specimens were analyzed with HE staining, immunohistochemistry, and cell counting in order to study the morphological and molecular changes that occurred in the tissues. Disruption of the microtubular array by nocodazole reduced cells expressing proliferation marker Ki67, osteogenic marker BSP, and BMP4 within the sphenooccipital synchondrosis region; chondrocyte hypertrophy was ceased in the hypertrophic zone; degeneration of cartilage matrix and bone matrix apposition was inhibited in the ossification center of the basooccipital cranial base. Our data demonstrated that disruption of microtubules by nocodazole have multiple inhibitory effects on the sequential changes that occur during endochondral bone formation, suggesting the importance of normal microtubule-polymerization in cranial base development.
Animals ; Bone Matrix ; Bone Morphogenetic Protein 4 ; Cartilage ; Cell Count ; Cell Death ; Chondrocytes ; Durapatite ; Hypertrophy ; Hypogonadism ; Immunohistochemistry ; Mice ; Microtubules ; Mitochondrial Diseases ; Nocodazole ; Ophthalmoplegia ; Organ Culture Techniques ; Osteogenesis ; Skull Base

The massive reorganization of microtubule network involves in transcriptional regulation of several genes by controlling transcriptional factor, nuclear factor-kappa B (NF-kappaB) activity. The exact molecular mechanism by which microtubule rearrangement leads to NF-kappaB activation largely remains to be identified. However microtubule disrupting agents may possibly act in synergy or antagonism against apoptotic cell death in response to conventional chemotherapy targeting DNA damage such as adriamycin or comptothecin in cancer cells. Interestingly pretreatment of microtubule disrupting agents (colchicine, vinblastine and nocodazole) was observed to lead to paradoxical suppression of DNA damage-induced NF-kappaB binding activity, even though these could enhance NF-kappaB signaling in the absence of other stimuli. Moreover this suppressed NF-kappaB binding activity subsequently resulted in synergic apoptotic response, as evident by the combination with Adr and low doses of microtubule disrupting agents was able to potentiate the cytotoxic action through caspase-dependent pathway. Taken together, these results suggested that inhibition of microtubule network chemosensitizes the cancer cells to die by apoptosis through suppressing NF-kappaB DNA binding activity. Therefore, our study provided a possible anti-cancer mechanism of microtubule disrupting agent to overcome resistance against to chemotherapy such as DNA damaging agent.
Animals ; Antibiotics, Antineoplastic/therapeutic use ; *Apoptosis ; Caspases/metabolism ; Cell Line ; Colchicine/pharmacology ; DNA/metabolism ; *DNA Damage ; Doxorubicin/therapeutic use ; Humans ; Mice ; Microtubules/chemistry/*drug effects/metabolism ; NF-kappa B/antagonists & inhibitors/*metabolism ; Neoplasms/drug therapy ; Nocodazole/pharmacology ; Protein Binding ; Signal Transduction ; Tubulin Modulators/*pharmacology ; Vinblastine/pharmacology

The process of injury and repair in airway epithelium involves cell spreading and migration followed by cell proliferation. IQ domain GTPase-activating protein 1 (IQGAP1) acts in a series of cell processes, but has not been clarified in lung epithelial cells. In this study, a widely used model of injury and repair in vitro by scratching bronchial epithelial cells (BECs) was utilized to investigate the function of IQGAP1. The results showed that IQGAP1 was abundant in BECs of mouse, rat, pig and human. IQGAP1 was colocalized with tubulin cytoskeleton, but was destroyed by nocodazole, a microtubule disassembly reagent. IQGAP1 mRNA and protein expressions increased at 6-9 h after scratching. In addition, overexpression of IQGAP1 translocated β-catenin from the cytoplasm into the nucleus and activated the Tcf/Lef signal. Scratching altered the associations of IQGAP1 with β-catenin, adenomatous polyposis coli (APC) and cytoplasmic linker protein-170 (CLIP-170). Silencing IQGAP1 expression by small interference RNA (siRNA) blocked the wound closure. It is concluded that IQGAP1 signal is involved in the wound closure of BECs induced by scratching.
Adenomatous Polyposis Coli Protein ; metabolism ; Animals ; Bronchi ; cytology ; Cell Proliferation ; Cells, Cultured ; Cytoskeleton ; metabolism ; Epithelial Cells ; cytology ; pathology ; Humans ; Mice ; Microtubule-Associated Proteins ; metabolism ; Neoplasm Proteins ; metabolism ; Nocodazole ; pharmacology ; Rats ; Swine ; Tubulin ; metabolism ; beta Catenin ; metabolism ; ras GTPase-Activating Proteins ; metabolism

Sec13p has been known as an endoplasmic reticulum-Golgi transport protein. Recently, it has also been shown to be required for the formation of septation in the fission yeast Schizosaccharomyces pombe. In the present study, we focused on the role of a human homolog of Saccharomyces cerevisiae SEC13, Sec13 protein during mitosis in U2OS cells. We found that the expression of Sec13 was constant throughout the cell cycle, and localized to the kinetochores at metaphase during mitosis. By using green fluorescent protein technology, we observed that Sec13 is required for evasion of mitotic arrest in response to spindle damage, leading to G1-like phase and apoptotic cell death. In addition, cells expressing exogenous Sec13 showed giant nuclei compared to endogenous ones in the absence of nocodazole. These results demonstrate that Sec13 is involved in the regulation of the metaphase/anaphase transition and may be functionally associated with mitotic machinery to maintain genomic stability during mitosis.
Anaphase ; Antineoplastic Agents/pharmacology ; Cell Line, Tumor/drug effects/metabolism/pathology ; *G1 Phase ; *Genomic Instability ; Green Fluorescent Proteins/metabolism ; Humans ; Kinetochores/metabolism ; Membrane Proteins/*genetics/metabolism ; Metaphase ; Mitosis/*physiology ; *Mitotic Spindle Apparatus ; Nocodazole/pharmacology ; Osteosarcoma/genetics/metabolism/pathology ; Research Support, Non-U.S. Gov't

OBJECTIVES: The development of an useful method for obtaining metaphase chromosomes from a biopsied blastomere would allow differentiation between embryos with balanced and normal chromosome complements in the preimplantation genetic diagnosis for chromosomal translocations. This study was performed to evaluate the effects of microtubule depolymerizing agents (MTDAs) on the blastomeres of mouse and human preimplantation embryos, and to establish an effective method for obtaining metaphase chromosomes of biopsied blastomeres in human early embryos. MATERIALS AND MEHTODS: Early embryos (2-4 cell stage) from superovulated mice (ICR strain) were collected and treated with single or mixture MTDAs, such as vinblastine, nocodazole and colcemid. After the treatment of MTDAs for 16 hours, the metaphase aquisition (MA) rates were evaluated by the observation of chromosome status with bis-benzimide or DAPI staining. The optimal condition from the above experiment was applied to human embryos, which were developed from abnormal fertilization (3-pronuclei). Fluorescence in-situ hybridization (FISH) with whole chromosome probes was conducted on the human metaphase chromosomes by the MTDAs. RESULTS: In mouse embryos, the effective concentrations of each MTDAs for obtaining metaphase chromosomes were 1.0 micrometer of vinblastine (20.3%), 5.0 micrometer of nocodazole (28.1%) and 1.0 micrometer colcemid (55.6%), respectively. The highest MA rate (91.2%) in the mouse embryos was obtained by a mixture of vinblastine (1.0 micrometer) and nocodazole (1.0 micrometer). In the human embryos, the metaphase chromosomes of blastomeres were obtained in 44 of 113 blastomeres (38.9%) by treatment of the mixture of vinblastine and nocodazole. FISH signals of the metaphase chromosomes were successfully observed in human individual blastomeres. CONCLUSIONS: The treatment of a mixture MTDAs for obtaining metaphase chromosomes was an efficient method, and the MA rate was above 90% in the mouse embryos. However, only a relatively small proportions of the blastomeres yielded metaphase chromosomes by the MTDAs in the human embryos. The inconsistent effects of MTDAs may be related to the variation of different species and the poor developmental potency of abnormally fertilized human embryos. We should develop more reliable and efficient methods for obtaining the metaphase chromosomes in the biopsied blastomeres of human preimplantation embryos.
Animals ; Blastocyst ; Blastomeres* ; Complement System Proteins ; Demecolcine ; Embryonic Structures* ; Fertilization ; Fluorescence ; Humans* ; Metaphase* ; Mice* ; Microtubules* ; Nocodazole ; Preimplantation Diagnosis ; Translocation, Genetic ; Vinblastine

OBJECTIVES: The development of an useful method for obtaining metaphase chromosomes from a biopsied blastomere would allow differentiation between embryos with balanced and normal chromosome complements in the preimplantation genetic diagnosis for chromosomal translocations. This study was performed to evaluate the effects of microtubule depolymerizing agents (MTDAs) on the blastomeres of mouse and human preimplantation embryos, and to establish an effective method for obtaining metaphase chromosomes of biopsied blastomeres in human early embryos. MATERIALS AND MEHTODS: Early embryos (2-4 cell stage) from superovulated mice (ICR strain) were collected and treated with single or mixture MTDAs, such as vinblastine, nocodazole and colcemid. After the treatment of MTDAs for 16 hours, the metaphase aquisition (MA) rates were evaluated by the observation of chromosome status with bis-benzimide or DAPI staining. The optimal condition from the above experiment was applied to human embryos, which were developed from abnormal fertilization (3-pronuclei). Fluorescence in-situ hybridization (FISH) with whole chromosome probes was conducted on the human metaphase chromosomes by the MTDAs. RESULTS: In mouse embryos, the effective concentrations of each MTDAs for obtaining metaphase chromosomes were 1.0 micrometer of vinblastine (20.3%), 5.0 micrometer of nocodazole (28.1%) and 1.0 micrometer colcemid (55.6%), respectively. The highest MA rate (91.2%) in the mouse embryos was obtained by a mixture of vinblastine (1.0 micrometer) and nocodazole (1.0 micrometer). In the human embryos, the metaphase chromosomes of blastomeres were obtained in 44 of 113 blastomeres (38.9%) by treatment of the mixture of vinblastine and nocodazole. FISH signals of the metaphase chromosomes were successfully observed in human individual blastomeres. CONCLUSIONS: The treatment of a mixture MTDAs for obtaining metaphase chromosomes was an efficient method, and the MA rate was above 90% in the mouse embryos. However, only a relatively small proportions of the blastomeres yielded metaphase chromosomes by the MTDAs in the human embryos. The inconsistent effects of MTDAs may be related to the variation of different species and the poor developmental potency of abnormally fertilized human embryos. We should develop more reliable and efficient methods for obtaining the metaphase chromosomes in the biopsied blastomeres of human preimplantation embryos.
Animals ; Blastocyst ; Blastomeres* ; Complement System Proteins ; Demecolcine ; Embryonic Structures* ; Fertilization ; Fluorescence ; Humans* ; Metaphase* ; Mice* ; Microtubules* ; Nocodazole ; Preimplantation Diagnosis ; Translocation, Genetic ; Vinblastine

PURPOSE: Nocodazole, a microtubule disrupting reagent, is known to arrest cells in the M phase, To gain insight on the regulatory mechanism of H2B histone gene expression by nocodazole in HL-60 cell, the binding pattern of nuclear proteins to cis element in the human H2B histone gene promoter has been investigated with DNase I footprinting and DNA mobility shift assay. MATERIALS AND METHODS: Northern blot hybridization was performed by the method of Virca et al. A Hinc II-Sac I fragment of pSPH28 was used as probe for Northern blot analysis of H2B histone mRNA. DNase I footprinting and DNA mobility shift assay were performed by the method of Lim et al. End labeled DNA oligomer (upper strand, 5'-CTTCACCTTATTTGCATAA GCGATTC-3') for octamer binding activity was mixed with nuclear extracts in a 20 ul reaction volume containing 60 mM KC1, 12 mM HEPES, pH 7.9, 5 mM MgCl2, 0.2 mM EDTA, 0.2 mM DTT, 12% glycerol, and 2 ug of poly [dI-dC]. RESULTS: The level of H2B histone mRNA rapidly was reduced at 24 hours in nocodazole-treated HL-60 cells and the mRNA was repressed in proportion to the concentration of nocodazole. Nocodazole-dependent repression of H2B histone gene was restored by replacement with nocodazole-free media. In DNase I footprinting analysis, one nuclear factor bound at 42 bp site (octamer motif) in the absence of nocodazole. In the presence of nocodazole, the binding of nuclear factor on octamer motif partially vanished. In DNA mobility shift assay, one DNA-protein complex (Octl) was formed when octamer motif was incubated with nuclear extract of HL-60 cell. After nocodazole treatment, Octl binding activity was reduced by time dependent manner. CONCLUSION: These results suggest that nocodazole-dependent repression of H2B histone gene is correlated with reduction of Octl binding activity in HL-60 cell.
Blotting, Northern ; Cell Division ; Deoxyribonuclease I ; DNA ; Edetic Acid ; Electrophoretic Mobility Shift Assay ; Gene Expression* ; Glycerol ; HEPES ; Histones* ; HL-60 Cells* ; Humans ; Hydrogen-Ion Concentration ; Magnesium Chloride ; Microtubules ; Nocodazole* ; Nuclear Proteins ; Repression, Psychology ; RNA, Messenger