Chapter 7 TRP Channels as Thermosensors

Abstract

Publisher Summary This chapter discusses the transient receptor potential (TRP) channels that are involved in temperature sensing, along with their biophysical properties and chemical activators. In humans, 28 different TRP genes have been identified and these can be grouped into 6 families: the classical TRP channels (TRPCs), the vanilloid receptor related TRP channels (TRPVs), the melastatin or long TRPs (TRPMs), the mucolipins(TRPMLs), the polycystins (TRPPs), and ankyrin transmembrane protein related channels (TRPA). The cloning and expression of TRP channels has revealed that TRPV1–4, TRPM8, and TRPA1 are thermosensitive with sensitivities spanning the relevant range of environmental and physiological temperatures. In addition, their expression patterns are consistent with major roles as thermosensors. Some of these TRP channels are clearly sensitive to non‐thermal stimuli and can act as polymodal receptors in sensory nerve cells and in other tissues. Following the identification of TRPV1, other TRP channels are found to encode sensitivity to hot, warm, cool, and cold temperatures. As TRPV1, TRPV2 is also activated by high temperatures over 52°C. TRPV3 shows a high degree of homology to TRPV1 and is activated by warm temperatures with a threshold of 33°C. TRPV3 is expressed in sensory neurons and keratinocytes located in close proximity to free nerve endings, indicating that the signaling of warm stimuli may involve both direct and indirect activation of sensory nerves.