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Effect of X-Irradiation at Different Stages in the Cell Cycle on Individual Cell-Based Kinetics in an Asynchronous Cell Population.

Tsuchida E, Kaida A, Pratama E, Ikeda MA, Suzuki K, Harada K, Miura M - PLoS ONE (2015)

Bottom Line: To visualize the cell-cycle phase, we employed the fluorescent ubiquitination-based cell cycle indicator (Fucci).The results revealed that endoreduplication rarely occurs in this cell line under the conditions we studied.The value was the largest when cells were irradiated in mid or late S phase and the smallest when they were irradiated in G1 phase.

View Article: PubMed Central - PubMed

Affiliation: Section of Oral Radiation Oncology, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan; Section of Maxillofacial Surgery, Department of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.

ABSTRACT
Using an asynchronously growing cell population, we investigated how X-irradiation at different stages of the cell cycle influences individual cell-based kinetics. To visualize the cell-cycle phase, we employed the fluorescent ubiquitination-based cell cycle indicator (Fucci). After 5 Gy irradiation, HeLa cells no longer entered M phase in an order determined by their previous stage of the cell cycle, primarily because green phase (S and G2) was less prolonged in cells irradiated during the red phase (G1) than in those irradiated during the green phase. Furthermore, prolongation of the green phase in cells irradiated during the red phase gradually increased as the irradiation timing approached late G1 phase. The results revealed that endoreduplication rarely occurs in this cell line under the conditions we studied. We next established a method for classifying the green phase into early S, mid S, late S, and G2 phases at the time of irradiation, and then attempted to estimate the duration of G2 arrest based on certain assumptions. The value was the largest when cells were irradiated in mid or late S phase and the smallest when they were irradiated in G1 phase. In this study, by closely following individual cells irradiated at different cell-cycle phases, we revealed for the first time the unique cell-cycle kinetics in HeLa cells that follow irradiation.

No MeSH data available.


Dose-dependency of prolongation of red and green phase after irradiation.(A) Schematic presentation of irradiation timing and measurement of the duration of green (a) or red (b) phase. Black square represents M phase. In panel b, the two daughter cells did not exhibit exactly the same red-phase duration; therefore, each value was separately measured and mean values were calculated. (B) Dose-dependency of prolongation of red and green phases after irradiation. Data represent means ± S.D. of values obtained from at least four different fields for each dose. Each field contained at least 10 cells. *, p < 0.05; **, p < 0.01 vs. control values at 0 Gy (one way ANOVA with post hoc Dunnett’s test).
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pone.0128090.g002: Dose-dependency of prolongation of red and green phase after irradiation.(A) Schematic presentation of irradiation timing and measurement of the duration of green (a) or red (b) phase. Black square represents M phase. In panel b, the two daughter cells did not exhibit exactly the same red-phase duration; therefore, each value was separately measured and mean values were calculated. (B) Dose-dependency of prolongation of red and green phases after irradiation. Data represent means ± S.D. of values obtained from at least four different fields for each dose. Each field contained at least 10 cells. *, p < 0.05; **, p < 0.01 vs. control values at 0 Gy (one way ANOVA with post hoc Dunnett’s test).

Mentions: To obtain individual cell–based information regarding prolongation of the red and green phases, we first set up simple experimental sequences, as depicted in Fig 2A. We examined how long the green phase was prolonged when cells in red phase were irradiated, and vice versa. The dose dependency is shown in Fig 2B. When cells in red phase were irradiated, the duration of the green phase excluding M phase (black square) increased in a dose-dependent manner. On the other hand, when cells in green phase were irradiated at doses up to 10 Gy, the duration of red phase did not significantly increase.


Effect of X-Irradiation at Different Stages in the Cell Cycle on Individual Cell-Based Kinetics in an Asynchronous Cell Population.

Tsuchida E, Kaida A, Pratama E, Ikeda MA, Suzuki K, Harada K, Miura M - PLoS ONE (2015)

Dose-dependency of prolongation of red and green phase after irradiation.(A) Schematic presentation of irradiation timing and measurement of the duration of green (a) or red (b) phase. Black square represents M phase. In panel b, the two daughter cells did not exhibit exactly the same red-phase duration; therefore, each value was separately measured and mean values were calculated. (B) Dose-dependency of prolongation of red and green phases after irradiation. Data represent means ± S.D. of values obtained from at least four different fields for each dose. Each field contained at least 10 cells. *, p < 0.05; **, p < 0.01 vs. control values at 0 Gy (one way ANOVA with post hoc Dunnett’s test).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4472673&req=5

pone.0128090.g002: Dose-dependency of prolongation of red and green phase after irradiation.(A) Schematic presentation of irradiation timing and measurement of the duration of green (a) or red (b) phase. Black square represents M phase. In panel b, the two daughter cells did not exhibit exactly the same red-phase duration; therefore, each value was separately measured and mean values were calculated. (B) Dose-dependency of prolongation of red and green phases after irradiation. Data represent means ± S.D. of values obtained from at least four different fields for each dose. Each field contained at least 10 cells. *, p < 0.05; **, p < 0.01 vs. control values at 0 Gy (one way ANOVA with post hoc Dunnett’s test).
Mentions: To obtain individual cell–based information regarding prolongation of the red and green phases, we first set up simple experimental sequences, as depicted in Fig 2A. We examined how long the green phase was prolonged when cells in red phase were irradiated, and vice versa. The dose dependency is shown in Fig 2B. When cells in red phase were irradiated, the duration of the green phase excluding M phase (black square) increased in a dose-dependent manner. On the other hand, when cells in green phase were irradiated at doses up to 10 Gy, the duration of red phase did not significantly increase.

Bottom Line: To visualize the cell-cycle phase, we employed the fluorescent ubiquitination-based cell cycle indicator (Fucci).The results revealed that endoreduplication rarely occurs in this cell line under the conditions we studied.The value was the largest when cells were irradiated in mid or late S phase and the smallest when they were irradiated in G1 phase.

View Article: PubMed Central - PubMed

Affiliation: Section of Oral Radiation Oncology, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan; Section of Maxillofacial Surgery, Department of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.

ABSTRACT
Using an asynchronously growing cell population, we investigated how X-irradiation at different stages of the cell cycle influences individual cell-based kinetics. To visualize the cell-cycle phase, we employed the fluorescent ubiquitination-based cell cycle indicator (Fucci). After 5 Gy irradiation, HeLa cells no longer entered M phase in an order determined by their previous stage of the cell cycle, primarily because green phase (S and G2) was less prolonged in cells irradiated during the red phase (G1) than in those irradiated during the green phase. Furthermore, prolongation of the green phase in cells irradiated during the red phase gradually increased as the irradiation timing approached late G1 phase. The results revealed that endoreduplication rarely occurs in this cell line under the conditions we studied. We next established a method for classifying the green phase into early S, mid S, late S, and G2 phases at the time of irradiation, and then attempted to estimate the duration of G2 arrest based on certain assumptions. The value was the largest when cells were irradiated in mid or late S phase and the smallest when they were irradiated in G1 phase. In this study, by closely following individual cells irradiated at different cell-cycle phases, we revealed for the first time the unique cell-cycle kinetics in HeLa cells that follow irradiation.

No MeSH data available.