Identifying the physical stimuli for activation and sensitization of Piezo mechanosensitive ion channels

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 DESCRIPTION (provided by applicant): Mechanosensitive ion channels are essential for mechanotransduction, or the conversion of mechanical force into a biologically relevant signal. Recently, two novel membrane-spanning proteins, Piezo1 and Piezo2, were identified as pore-forming subunits of a vertebrate mechanosensitive ion channel. Piezos open in response to diverse mechanical stimuli, leading to an influx of cations; this in turn leads to depolarization o the cell membrane and initiation of downstream pathways. Piezos are required for responses to light touch in Merkel cells and normal development of the vascular system. Moreover, disruption of Piezo ion channel function is implicated in several human diseases and may contribute to hyperalgesia associated with inflammatory pathways. Piezos share little homology with other ion channels, and despite their important role in normal physiology many aspects of their function remain unknown. In particular, the specific forces on the membrane and/or channel that lead to pore opening have yet to be established. The experiments proposed here are designed to elucidate the activation mechanism of Piezos. Specifically, they test the contributions of membrane curvature and/or tension as potential physical stimuli that Piezos sense. Additionally, these experiments will examine the mechanisms by which inflammatory compounds as well as native inactivation modulate the sensitivity of Piezos to a given stimulus. Identifying the physica stimulus that activates Piezos and the means by which it can be modulated will help further the understanding of the role of these proteins in abnormal physiology, as well as inform pharmacological targeting.