Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.25.353904v1?rss=1 Authors: Li, F., Park, T. H., Sankin, G., Gilchrist, C., Liao, D., Chan, C. U., Mao, Z., Hoffman, B. D., Zhong, P. Abstract: Ultrasound or shockwave-induced cavitation is used therapeutically to stimulate neural and muscle tissue, but the mechanisms underlying this mechanotransduction are unclear. Intracellular calcium signaling is one of the earliest events in mechanotransduction. In this study, we investigate the mechanism of calcium signaling in individual HEK293T cells stimulated by single cavitation bubbles. Calcium responses are rare at cell-bubble distance that avoids membrane poration, even with overexpression of the mechanosensitive ion channel Piezo1, but could be increased in frequency to 42% of cells by attaching RGD beads to the apical surface of the cells. By using Piezo1 knockout and Piezo1-expressing cells, integrin-blocking antibodies, and inhibitors of P2X ion channels, key molecular players are identified in the RGD bead-enhanced calcium response: increased integrin ligation by substrate ECM triggers ATP release and activation of P2X-but not Piezo1-ion channels. These molecular players have not been examined previously in cavitation-induced calcium signaling. The resultant calcium influx causes dynamic changes in cell spread area. This approach to eliciting a calcium response with cavitation microbubbles without cell injury, and the uncovered mechanotransduction mechanism by which increased integrin-ligation mediates ATP release and calcium signaling will inform new strategies to stimulate tissues with ultrasound and shockwaves. Copy rights belong to original authors. Visit the link for more info