"Studying genes implicated in mechanosensation using Patch-Seq"
Little is known about the ion channels that account for mechanical sensitivity in sensory neurons. Indeed, mechanical stimulation of sensory neurons can elicit at least three types of excitatory mechanically-activated (MA) currents distinguishable by their adaption kinetics to prolonged stimuli. These currents result from the activation of MA ion channels. Only PIEZO2 is known to play a crucial role in innocuous touch sensing and proprioception. However, it is not involved in acute mechanical pain sensing, suggesting the existence of other(s) MA channel(s).
We combined whole-cell electrophysiological patch-clamp recordings and single cell RNA sequencing to unravel molecular components of MA channels. Following electrophysiological characterization upon mechanic stimulation, cell contents were aspirated through the patch-clamp pipette and prepared for RNA sequencing by NGS.
Based on transcriptome comparisons, in silico analysis, we showed that gene expression patterns can infer the electrophysiological properties upon mechanical stimulation. Using this approach, we provided lists of differentially expressed genes which potentially code for molecular components of MA channels. The implication of these candidate genes in the distinct types of MA currents was tested by patch-clamp recordings in freshly isolated mouse sensory neurons after siRNA-mediated knock-down.
Our data shed light on the molecular underpinning of sensory neurons diversity and could lead to the identification of new MA channel component(s) or modulator(s) and to a better understanding of mammalian mechanosensation.