Cytoskeleton Dependent Activation of Tentonin3/TMEM150C, a Novel Mechanosensitive Channel

Abstract

Tentonin 3/TMEM150C (TTN3) has been recently discovered as a novel mechanosensitive (MS) channel. It is activated by mechanical stimuli followed by slow inactivation in the heterologous system, distinct from Piezo1 or 2 that has a rapid inactivation. However, the activation mechanism of TTN3 has been challenged. Because TTN3 fails to show MS currents in Piezo1-deficient HEK (HEK-P1KO) cells, TTN3 is considered to be a regulatory protein controlling Piezo1 activity. To address this issue, we hypothesized that mechanosensitivity of TTN3 depends on the cytoskeleton integrity of the cell. Here, we found that loss of TTN3 MS current in HEK-P1KO is highly correlated with the focal adhesion (FA) complex. When the F-actin assembly is strengthened after jasplakinolide-treatment, mechanical stimuli robustly evoked MS currents in Ttn3-transfected HEK-P1KO cells. HEK-P1KO cells showed dramatic loss of FA proteins and knockdown of FA proteins in HEK cells also reduced the TTN3-dependent MS currents. Thus, we conclude that mechanosensitivity of TTN3 is dependent on the cytoskeleton integrity. This finding supports the idea that TTN3 is an essential component of the slowly inactivating MS channel complex.