Atsushi Kaida

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Although oxygen is required for functional chromophore formation during the maturation process of fluorescent proteins, the effects of hypoxia on their fluorescence have rarely been studied in mammalian cells. We recently reported that severe hypoxia (pO(2)<0.1%) abrogates fluorescence from the fluorescent ubiquitination-based cell cycle indicator (Fucci)(More)
Fucci (fluorescent ubiquitination-based cell cycle indicator) is able to visualize dynamics of cell cycle progression in live cells; G1- and S-/G2-/M-phase cells expressing Fucci emit red and green fluorescence, respectively. This system could be applied to cell kinetic analysis of tumour cells in the field of cancer therapy; however, it is still unclear(More)
Fluorescent proteins are widely used for the direct visualization of events such as gene expression and subcellular localization in mammalian cells. It is well established that oxygen is required for formation of functional chromophore; however, the effect of hypoxia on fluorescence emission has rarely been studied. For this purpose, under hypoxic(More)
Plinabulin (NPI-2358) is a novel microtubule-depolymerizing agent. In HeLa cells, plinabulin arrests the cell-cycle at M phase and subsequently induces mitotic catastrophe. To better understand the effects on this compound on the cell-cycle, we used the fluorescent ubiquitination-based cell cycle indicator (Fucci), which normally enables G1 and S/G2/M cells(More)
The mitotic shake-off method revealed the remarkable variation of radiosensitivity of HeLa cells during the cell cycle: M phase shows the greatest radiosensitivity and late S phase the greatest radioresistance. This method harvests all M-phase cells with a round shape, making it impossible to further subdivide M-phase cells. Recently, the fluorescent(More)
The effect of ionizing radiation on cell cycle kinetics in solid tumors remains largely unknown because of technical limitations and these tumors' complicated structures. In this study, we analyzed intratumoral cell cycle kinetics after X-irradiation of tumor xenografts derived from HeLa cells expressing the fluorescent ubiquitination-based cell cycle(More)
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(More)
In this study, we visualized the effect of tumor microenvironments on radiation-induced tumor cell kinetics. For this purpose, we utilized a multicellular spheroid model, with a diameter of ∼500 μm, consisting of HeLa cells expressing the fluorescent ubiquitination-based cell-cycle indicator (Fucci). In live spheroids, a confocal laser scanning microscope(More)
Hypoxia induces G1 arrest in many cancer cell types. Tumor cells are often exposed to hypoxia/reoxygenation, especially under acute hypoxic conditions in vivo. In this study, we investigated cell-cycle kinetics and clonogenic survival after hypoxia/reoxygenation in HeLa cells expressing fluorescent ubiquitination-based cell cycle indicator (Fucci). Hypoxic(More)
Chk1 inhibitor acts as a potent radiosensitizer in p53-deficient tumor cells by abrogating the G2/M checkpoint. However, the effects of Chk1 inhibitor on the duration of G2 arrest have not been precisely analyzed. To address this issue, we utilized a cell-cycle visualization system, fluorescent ubiquitination-based cell-cycle indicator (Fucci), to analyze(More)