Mechanosensory calcium-selective cation channels in epidermal cells

Area of Science:

• Plant Cell Biology
• Biophysics
• Ion Channel Physiology

Background:

• Epidermal cells possess complex ion channel systems.
• Mechanosensitive ion channels play crucial roles in cellular responses to physical stimuli.
• Understanding these channels is key to deciphering cellular mechanotransduction.

Purpose of the Study:

• To investigate the properties and functions of a tension-activated, calcium-selective cation channel complex in the epidermis.
• To elucidate the regulatory mechanisms and potential in vivo roles of this mechanosensitive channel.

Main Methods:

• Electrophysiological analysis of excised plasma membrane patches.
• Application of controlled suction and varying concentrations of ions (Mg2+, Ca2+, Gd3+, La3+).
• Investigation of channel response to transmembrane voltage, temperature, and specific chemical modulators.

Main Results:

• The channel complex comprises multiple conductance units that can open synchronously.
• Channel gating is influenced by millimolar Mg2+ and regulated by transmembrane voltage and temperature.
• Specific lanthanides and ethyl-N-phenylcarbamate modulate channel activity, affecting tension sensitivity and gravitropic signaling.

Conclusions:

• The epidermal Ca(2+)-selective cation channel functions as both a mechanosensor and mechanoregulator.
• It transduces mechanical forces from cell wall-cytoskeleton-membrane interactions during turgor changes, cell expansion, and responses to gravity and touch.
• Voltage and temperature modulate this transduction, indicating the channel also senses these modalities under mechanical stress.