Decreased cold-sensing function of the transient receptor potential channel TRPM8 from tailed amphibians.

Sensing environmental temperature is a complex process involving an array of channels expressed by nociceptive sensory neurons but is critical to allow animals to move away from suboptimal environments and find environments with ideal temperatures. Focusing on one such channel (the transient receptor potential channel TRPM8), we have investigated the function of this channel across four tailed amphibians, which prefer cooler environments, studied behavioral responses to cold temperature, and characterized their TRPM8 function. Unlike frogs, which are known to prefer warmer climates, we observed that tailed amphibians do not show escaping behavior to avoid cold temperatures. Examination of the temperature-response profiles of TRPM8 channels across these species demonstrated that tailed amphibian TRPM8 commonly has diminished cold sensitivity compared to frog TRPM8. Furthermore, we identify that eight amino acids at the N terminus of the TRPM8 protein determine the low-temperature sensitivity of the channel. While further work is necessary to understand how these amino acids regulate the cold-induced opening of the TRPM8 channel, these results represent key findings highlighting the role of TRPM8 in environmental temperature sensing.