BACKGROUND: Mutations in the human Cu, Zn-superoxide dismutase(SOD1) gene have been identified in some cases of familial amyotrophic lateral sclerosis(ALS). The aim of this study is to delineate the effect of the SOD1 mutation on neural differentiation, and to investigate the mechanism of neuronal death. METHODS: We studied motorneuron-neurob-lastoma hybrid cells(VSC 4.1) expressing wild type or mutant SOD1(G93A, A4V) during differentiation by dibutyryl cAMP and aphidicolin. RESULTS: Mutant cells(G93A) revealed a decreased viability compared with the control cells, mainly in the early stage ofdifferentiation. The release of cytochrome c and increased nuclear fragmentation were observed. However, cell death was not protected by nonselective caspase inhibitor(z-VAD-fmk), but by the antioxi-dant( Trolox). CONCLUSIONS: The results suggest that oxidative stress may be the main mechanism of neuronal death, particularly in the early stage of differentiation.
Aphidicolin ; Cell Death ; Cytochromes c ; Humans ; Motor Neurons* ; Neurons ; Oxidative Stress

BACKGROUND: Mutations in the human Cu, Zn-superoxide dismutase (SOD1) gene have been identified in some cases of familial amyotrophic lateral sclerosis (ALS). Neuronal cells with mutant SOD1 gene promoted cell death during differentiation by dibutyryl cAMP and aphidicolin. The aim of this study is to delineate if there is an impairment of the neural differentiation process in mutant SOD1 cells. METHODS: We studied the motoneuron-neuroblastoma hybrid cells (VSC 4.1) expressing wild-type or mutant SOD1 (G93A) during the differentiation by dibutyryl cAMP and aphidicolin. RESULTS: Mutant SOD1 cell (G93A) showed an impairment in the neurite formation. Western blot analysis revealed that the amount of neurofilament decreased before differentiation. A decrease in the amount of MAP-2 is observed during differentiation. CONCLUSIONS: Our results suggest that the impairment in the neurite formation of mutant SOD1 cell (G93A) is a differentiation failure and is associated with neuronal cell death.
Amyotrophic Lateral Sclerosis ; Aphidicolin ; Blotting, Western ; Cell Death ; Humans ; Hybrid Cells ; Neurites* ; Neurons

To investigate fragile sites induced by aphidicolin which is a specific inhibitor of eukaryotic DNA polymerase a which is primarily associated with chromosomal DNA replication in human lymphocytes, HaCat cells (human keratinocytes) and MRC-5 cells (human embryonic lung fibroblast), we cultured each cells in RPMI 1640 with 10% fetal calf serum and 2% PHA. Treatment of the cells with aphidicolin was generally carried out for the last 24 hours of culturing. The drug was dissolved in DMSO and used at final concentrations of 0.05~0.15 mg/ml, corresponding to a maximum DMSO concentration of 0.028%. Karyotypes of each cells were performed by routine method, and 50 metaphases were scored for each culture for analysis of breakage rate. Experimental cells treated with APC showed a dose dependent sensitivity and the amounts of chromosome breakage induced by APC are the highest in concentration of 0.15 mg/ml. The frequency of fragile sites on each cells appeared in MRC-5 cells, lymphocytes and HaCat cells in order. The common fragile sites on all experiments was 16q23, and the common fragile sites on embryonic cells was 1p31. It can be concluded that gene or nucleic acid which is located on 16q23 is the most important factor to induce chromosomal breakage with sensitivity to aphidicolin and 1p31 is important site to induce chromosomal breakage in embryonal cells.
Aphidicolin* ; Chromosome Breakage ; Dimethyl Sulfoxide ; DNA ; DNA Replication ; Humans ; Karyotype ; Lung ; Lymphocytes* ; Metaphase

An aphidicolin is a chemical agent which selectively inhibits DNA polymerase alpha in S phase of cell cycle. The purpose of this study is toinvestigate of chromosomal abnormalities including fragile sites induced by 0.2 microgram/ml and 0.4 ng/ml aphidicolin in lymphocyte cultures of six healthy individuals. The results were follows. 1. A significant decreasing in mitotic indexes in respect to control culture was observed with both aphidicolin concentrations used. 2. The cells showing chromosome aberrations and the total number of cytogeneticic alterations were significantly increased both aphidicolin treated cultures than control cultures. 3. The total numbers of chromosomal aberrations were increased in the concentration of 0.4 microgram/ml aphidicolin compared to 0.2 microgram/ml treated groups. 4. The most frequent type of chromosomal aberration is a gap. 5. A site showing a gap or break was defined as common fragile sites (c-fra) if it appeared more than 1% of cells analyzed and in at least three of six individuals studied with the same culture treatment. Using these criteria, 3p14, 4q12, 5p13, 6q16, 9p13, and 16q23 were induced in different proportions by different concentration of aphidicolin and four of these c-fras, 4q12, 5p13, 6q16, 9p13 have not been reported so far. This results support that aphidicolin induced fragile sites differently according to cultured cell or cultured conditions, and also suggest the mechanism that common fragile sites caused be closely related with the defect of DNA synthesis in the S phase of cell cycle.
Aphidicolin* ; Cell Cycle ; Cells, Cultured ; Chromosome Aberrations ; Cytogenetics ; DNA ; DNA Polymerase I ; Humans* ; Lymphocytes* ; Mitotic Index ; S Phase

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

OBJECTIVETo assess DNA repair capacity of human lymphocytes with comet assay.

METHODSFresh lymphocytes form twelve 26-year old donors (6 males, 6 females) were exposed to ultraviolet C (UVC, 254 nm) at the dose rate of 1.5 J/m(2). The lymphocytes of each donor were divided into three parts: UVC group, UVC + aphidicolin (APC) group, UVC + novobiocin (NOV) group. DNA single strand breaks were detected with comet assay in UVC-irradiated cells and unirradiated cells incubated for 30, 60, 90, 120, 180 and 240 min. DNA repair rate (DRR) was calculated and served as an indicator of DNA repair capacity.

RESULTSThe maximum average comet tail length (MTL) in three groups appeared 90 min after UVC exposure. The DRR range of UVC group was 81.84% (62.84% - 98.71%); There was no significant difference in DRR between males and females (P > 0.05). However, the average DRRs of UVC + NOV group and UVC + APC group (52.98% and 39.57% respectively) were significantly lower than that of UVC group (P < 0.01).

CONCLUSIONComet assay is a rapid and simple screening test to assess DNA repair capacity. DRR, as an indicator, may express the individual DNA repair capacity.

Aphidicolin ; pharmacology ; Comet Assay ; methods ; DNA ; drug effects ; genetics ; radiation effects ; DNA Repair ; Enzyme Inhibitors ; pharmacology ; Female ; Humans ; Lymphocytes ; drug effects ; metabolism ; radiation effects ; Male ; Novobiocin ; pharmacology ; Ultraviolet Rays

OBJECTIVEAlkaline comet assay was used to evaluate DNA repair (nucleotide excision repair, NER) capacity of human fresh lymphocytes from 12 young healthy non-smokers (6 males and 6 females).

METHODSLymphocytes were exposed to UV-C (254 nm) at the dose rate of 1.5 J/m2/sec. Novobiocin (NOV) and aphidicolin (APC), DNA repair inhibitors, were utilized to imitate the deficiency of DNA repair capacity at the incision and ligation steps of NER. Lymphocytes from each donor were divided into three grougs: UVC group, UVC plus NOV group, and UVC plus APC group. DNA single strand breaks were detected in UVC irradiated cells incubated for 0, 30, 60, 90, 120, 180, and 240 min after UVC irradiation. DNA repair rate (DRR) served as an indicator of DNA repair capacity.

RESULTSThe results indicated that the maximum DNA damage (i.e. maximum tail length) in the UVC group mainly appeared at 90 min. The ranges of DRRs in the UVC group were 62.84%-98.71%. Average DRR value was 81.84%. The DRR difference between males and females was not significant (P < 0.05). However, the average DRR value in the UVC plus NOV group and the UVC plus APC group was 52.98% and 39.57% respectively, which were significantly lower than that in the UVC group (P < 0.01).

CONCLUSIONThe comet assay is a rapid, simple and sensitive screening test to assess individual DNA repair (NER) capacity. It is suggested that the time to detect DNA single strand breaks in comet assay should include 0 (before UV irradiation), 90 and 240 min after exposure to 1.5 J x m(-2) UVC at least. The DRR, as an indicator, can represent the individual DNA repair capacity in comet assay.

Adult ; Aphidicolin ; pharmacology ; Comet Assay ; methods ; DNA Damage ; drug effects ; radiation effects ; DNA Repair ; drug effects ; genetics ; radiation effects ; Enzyme Inhibitors ; pharmacology ; Female ; Humans ; Lymphocytes ; drug effects ; metabolism ; radiation effects ; Male ; Novobiocin ; pharmacology ; Risk Assessment ; Time Factors ; Ultraviolet Rays ; adverse effects