Genetic variation as a tool for identifying novel transducers of itch
The mammalian somatosensory system mediates itch, the irritating sensation that elicits a desire to scratch. Millions of people worldwide suffer from chronic itch that fails to respond to current drugs and therapies. Even though recent studies have begun to elucidate the basic characteristics of the itch circuitry, we have little understanding about the molecules and signaling mechanisms that underlie detection and transduction of itch sensation, especially during chronic itch conditions. We have taken a genomic approach by harnessing natural variation in itch-evoked scratching behaviors in mice to identify novel molecular players that are involved in itch signal transduction at the level of primary sensory neurons. From our analysis, we identified numerous candidate itch genes, and further identified a serotonin receptor, HTR7 as a key transducer that is required for both development and maintenance of chronic itch. We further investigated the genetic basis of variation in itch, and identified a set of genes and regulatory pathways that may be involved in controlling itch behaviors. Our work illustrates the power of genomic studies in identifying genes and regulatory pathways involved in somatosensory behaviors, further providing resources and molecular insights into possible treatment options for chronic itch conditions.