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IBEC Seminar: Slav Bagriantsev
Friday, November 15 @ 10:00 am–11:30 am
3D architecture and mechanism of touch detection in the Pacinian corpuscle
Slav Bagriantsev, Associate Professor of Cellular & Molecular Physiology, Yale School of Medicine, USA
Pacinian corpuscles are specialized mechanoreceptor end-organs that detect transient touch and high-frequency vibration in the skin and viscera of many vertebrates. Corpuscles have a complex cellular organization, which includes a mechanoreceptor afferent surrounded by lamellar Schwann cells (LSCs) and several layers of outer core cells. How these components contribute to the sensory tuning of Pacinian corpuscles is unclear. We used Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) to determine the detailed 3D architecture of an entire Pacinian corpuscle, including all corpuscular components, and utilized electrophysiology to reveal the contribution of each component to touch detection. In the prevailing model, the multilayered outer core serves as a mechanical filter that limits static and low-frequency stimuli from reaching the afferent terminal—the presumed sole site of touch detection in corpuscles. We show that the outer core is dispensable for the sensory tuning of Pacinian corpuscles to transient touch and high-frequency vibration; instead, these properties arise from the inner core. We show that LSCs express mechanically gated ion channels and form a gap junction-coupled syncytium around the afferent terminal. By acting as additional touch sensors, LSCs potentiate mechanosensitivity of the terminal, which detects touch via fast inactivating ion channels. We present a new model, in which the functional tuning of Pacinian corpuscles is enabled by an interplay between mechanosensitive LSCs and the afferent terminal in the inner core.
