PT  - JOURNAL ARTICLE
AU  - Hayakawa, Kimihide
AU  - Tatsumi, Hitoshi
AU  - Sokabe, Masahiro
TI  - Actin stress fibers transmit and focus force to activate mechanosensitive channels
AID  - 10.1242/jcs.022053
DP  - 2008 Feb 15
TA  - Journal of Cell Science
PG  - 496--503
VI  - 121
IP  - 4
4099  - http://jcs.biologists.org/content/121/4/496.short
4100  - http://jcs.biologists.org/content/121/4/496.full
SO  - J. Cell Sci.2008 Feb 15; 121
AB  - Mechanosensitive (MS) channels are expressed in various cells in a wide range of phylogenetic lineages from bacteria to humans. Understanding the molecular and biophysical mechanisms of their activation is an important research pursuit. It is controversial whether eukaryotic MS channels need accessory proteins – typically cytoskeletal structures – for activation, because MS channel activities are modulated by pharmacological treatments that affect the cytoskeleton. Here we demonstrate that direct mechanical stimulation (stretching) of an actin stress fiber using optical tweezers can activate MS channels in cultured human umbilical vein endothelial cells (HUVECs). Furthermore, by using high-speed total internal reflection microscopy, we visualized spots of Ca2+ influx across individual MS channels distributed near focal adhesions in the basal surface of HUVECs. This study provides the first direct evidence that the cytoskeleton works as a force-transmitting and force-focusing molecular device to activate MS channels in eukaryotic cells.