Ca2+ wave as a regulatory message tool for cellular communication

Waves of concentration change of specific signal molecules play an important role in signal exchanges between cells. To response to stimulus from outside of the cellular system they might communicate each other using waves. In this study, we focus on Ca2+ functioning as second messenger within cells. Normally, Ca2+ are stored in endoplasmic reticulum (ER). In response to the environmental stimulus, the Ca2+ channels on the ER membrane could be gated and induce a repetition of temporary ups and downs of the Ca2+ concentration in a cell. This “wave”, so-called Ca2+ concentration oscillation, has been predicted to regulate various physiological functions in cells. We investigate whether this temporal oscillation arises when cells are exposed to ionizing radiation. In this study, first, we tried to establish a measurement technique to visualize the Ca2+ concentration in mammalian cells. Normal human fibroblast cells were treated with a Ca2+ specific chemical fluorescent probe, Fluo 4. Then live-cell observations were performed with a fluorescent microscope to obtain time-lapse movies. Fluorescent intensities of the cells at each time point were converted to relative values to that at the beginning time of observation. Slight changes of the fluorescence in the most cells were recognized. Furthermore, some cells transiently showed intensive ups and downs of their fluorescence, indicating the occurrence of the Ca2+ waves. Using this method, for the next step, we challenge to detect local Ca2+ concentration oscillation in cell nucleus or organelle after exposure of ionizing radiation.
第3回QST国際シンポジウム「Quantum Life Science」