Inhibition of UV-induced DNA Damage of Cells by Hydrostatic Pressure

Abstract

Kaoru UESUGI, Kenya SATO and Kazuaki NAGAYAMA Cells are affected by various mechanical stimulations and change their mechanical and physiological properties. Recently, we found that mechanical stress possibly inhibits the ultraviolet (UV)-induced DNA damage of cells. Thus, in this study, the morphological change and the UV damage of nuclear DNA of cultured cells exposed to hydrostatic pressure were evaluated. First, a hydrostatic pressure-imposing experimental setup was constructed and morphological change of rat smooth muscle cell’s (A7r5) nucleus was evaluated. The results showed that the shape of the nucleus of cells exposed to hydrostatic pressure came close circle and the projected area and the volume decreased. The height of the nucleus did not change significantly. Then, the UV damage of nuclear DNA of A7r5 cells exposed to hydrostatic pressure was evaluated. An evaluation of breakage of DNA with γ-H2AX shown that the UV damage of cells exposed to hydrostatic pressure was inhibited. An evaluation using nuclear staining was shown that the UV damage of cells exposed to hydrostatic pressure was more decreased than that of cells unexposed, simultaneously with intranuclear DNA aggregations. These results mean that the DNA aggregation that occurred by a decrease of nuclear shape may work as a physical barrier against UV irradiation.