Mechanosensitive Currents in Merkel Cells

Abstract

Merkel cells are mechanosensory cells known to be touch cells about 160 years ago. However, its mechanism of how transduce and encode for touch sensation is still unknown. The objective of the present study is to characterize mechanosensitive currents in Merkel cells and investigate which ion channels are related to mechanotransduction in Merkel cells. By patch-clamp technique, we characterized mechanically activated (MA) currents in cultured mouse Merkel cells from whisker hair follicles. Merkel cells displayed mixed MA currents, rapidly adapting and slowly adapting currents. We confirmed that those currents were MA currents since they were inhibited by Gadolinium (Gd3+) and GsMTx4. Piezo2 and Tentonin3 ion channels were highly expressed in cultured mouse Merkel cells. We investigated the function of Piezo2 and Tentonin3 in Merkel cells. Knockdown of Piezo2 and Tentonin3 by siRNA transfection significantly reduced amplitude of MA currents in Merkel cells. Interestingly, Tentonin3 siRNA transfected Merkel cells showed higher reduction percentage of slowly adapting currents than other current types. We proposed that Tentonin3 plays role in MA currents in Merkel cells, especially in slowly adapting currents. This study on mechanosensitive currents in Merkel cells will provide basic information of Tentonin3 and more research remains to be done to understand function of Tentonin3.