Kei Sadakane

Photo-control of the mitotic kinesin Eg5 using a novel photochromic inhibitor composed of a spiropyran derivative

In this study, we synthesized a novel photochromic inhibitor of the mitotic kinesin Eg5, which is composed of the photochromic compound spiropyran to photo-control the function of Eg5. The compound (S)-2, 3-dispiropyran propionic acid (DSPPA) exhibits reversible spiropyran-merocyanine photo-isomerization upon irradiation with visible or ultra-violet light. DSPPA induced reversible changes in the inhibitory effect on Eg5 ATPase and motor activities, which correlates with the spiropyran-merocyanine photo-isomerization. Microtubule-dependent ATPase activity was significantly more inhibited by the spiropyran isomer of DSPPA than by the merocyanine isomer. Additionally, an in vitro motility assay revealed that the microtubule gliding velocity was reduced more by the spiropyran isomer than by the merocyanine isomer. This indicates that the spiropyran derivative may be useful in regulating the function of the mitotic kinesin.

Glioblastoma growth inhibition by low-power laser irradiation

It has been reported that low-power laser irradiation (LLI) can modulate various biological processes including cell proliferation. Some reports suggest LLI interferes with cell cycle and inhibits cell proliferation, while others suggest LLI has a stimulatory effect. Mechanism underlying the effect of LLI remains unclear. We have reported that 808 nm (60 mW) LLI has a potential of suppressive effect on the cell proliferation of human-derived glioblastoma A-172. To reveal a wavelength dependency of such an effect, the present studies using 2 other kinds of diode laser generators (405 nm with 27 mW and 532 nm with 60 mW) were designed. The A-172 cells were cultivated in culture dishes or a 96-well plate. No irradiation was applied in control-group, whereas in experimental group, the center of dish or the selected well was irradiated for 20, 40 and 60 min, respectively. Cells were cultivated in CO2 incubator for 1 or 2 days. The dishes or wells were photographed at pre-, just post-irradiation, 24 and 48 hrs after irradiation with a digital camera. Cell countings were performed on the PC screen and the ratio of cell proliferation was measured. MTT colorimetric analysis was also applied at 48 hrs after irradiation and viable cells and cell proliferation were estimated. These analyses showed that 405 nm LLI provided a significant suppressive effect on the proliferation of A-172 cells (p < 0.05 or p < 0.01), and the effect of LLI had a dose-dependency, whereas 532 nm LLI showed a significant stimulatory effect on them (p < 0.05 or p < 0.01), and also had a dose-dependency. Taking the results of 808 nm (60 mW) application into consideration, it is concluded that LLI effects on A-172 cell proliferation have a wavelength dependency.

Effects of low-power laser irradiation on proliferation of human-derived glioblastoma A-172

N-terminal peptide of mouse Prune2. Human PRUNE2 cDNA encodes a protein that consists of 3,063 amino acids. Western blotting demonstrated the presence endogenous Prune2 protein. Quantitative RT-PCR analysis revealed that the expression of PRUNE2 in brain is the highest among human tissues examined. We demonstrated that Prune2 is a huge protein with the Prune homology domain at the N-terminus and a BCL2/adenovirus E1B interacting protein 2 (BNIP2) and Cdc42GAP homology domain at the C-terminus.