Low-cost functional plasticity of TRPV1 supports heat tolerance in squirrels and camels

Thirteen-lined ground squirrels and Bactrian camels are capable of withstanding elevated environmental temperatures. In mammals, the polymodal transient receptor potential vanilloid 1 (TRPV1) ion channel responds to temperatures >40 °C and marks peripheral neurons responsible for detecting noxious heat. However, we find that both squirrels and camels express TRPV1 channels with dramatic decreases in thermosensitivity in the physiologically relevant range. To regain heat sensitivity, squirrel and camel TRPV1 require substitution of a single conserved amino acid. These data point to a common molecular mechanism used by camels and squirrels to adapt to high temperatures and reveal a remarkable functional plasticity of temperature activation of the TRPV1 channel.