Exploring molecular mechanisms of itch and touch in the mammalian somatosensory system.

Unlike other sensory systems, the somatosensory system is required for encoding information about multiple sensory modalities. Somatosensory neurons can respond to a variety of different stimuli including temperature, pressure and chemical irritants. These neurons are a heterogeneous population and utilize a variety of molecular pathways to transduce somatosensory stimuli. Because of this diversity of pathways and the diversity of sensory neuron subtypes, our understanding of transduction machinery in the somatosensory system lags behind our understanding of other sensory systems. We have worked to establish new tools for identifying new candidate molecules involved in transducing somatosensory stimuli and to test the role of these molecules in vitro and in vivo. Our work has focused on the transduction of two types of stimuli; mechanical forces that do not cause pain and chemical irritants that elicit sensations of itch. We have shown that TRPA1 is a convergence point for multiple itch causing compounds. We have also generated a new set of putative mechanotransducers by exploiting the extreme specialization of the hypertrophied epidermis of the star organ in the star-nosed mole. We have tested the role of one of these candidates, Cnga2, in somatosensation in mice. Our data suggests that Cnga2 plays a role in texture discrimination though altering the mechanical responses of somatosensory neurons.