Functional diversity and evolutionary dynamics of thermoTRP channels.

Animals have evolved sophisticated physiological systems for sensing ambient temperature since changes in environmental temperatures affect various biological processes. Thermosensitive transient receptor potential (thermoTRP) channels serve as thermal sensors in diverse animal species. They are multimodal receptors that are activated by temperature as well as other physical and chemical stimuli. Since thermoTRP channels are calcium permeable non-selective cation channels, their activation leads to an influx of calcium and sodium ions into the cell and triggers downstream signal transduction. ThermoTRP channels have been characterized in diverse animal species over the past several years, illuminating the diversification of thermoTRP channels in the course of evolution. The gene repertoires of thermoTRP channels differ among animal species. Additionally, in some cases, the temperature and chemical sensitivities among orthologous thermoTRP channels vary among species. The evolutionary flexibility of thermoTRP channels enabled them to contribute to unique physiological systems such as infrared sensation in snakes and bats and seasonal adaptation in silk moth. On the other hand, the functional differences of thermoTRP channels among species have been utilized for understanding the molecular basis for their activation (or inhibition) mechanisms, and amino acid residues (or domains) responsible for the respective channel properties have been identified in various thermoTRP channels. Here we summarize the current understanding of the functional diversity and evolutionary dynamics of thermoTRP channels.