Biology subjects

Lechner, S. G.

Publications and source records attributed to Lechner, S. G..

9 recordsLinked to original sources

bioRxiv2026

State-dependent binding of the wedge domain controls inactivation of the mechanosensitive ion channel PIEZO1

The mechanically activated ion channel PIEZO1 transduces membrane tension into intracellular calcium signals and is critical for a wide range of physiological processes. Recent structural and functional studies have established a detailed framework for PIEZO1 activation, but the molecular mechanisms governing its rapid inactivation remain incompletely understood. Here, we examined the contribution of the intracellular wedge domain to PIEZO1 inactivation using site-directed mutagenesis, electrophysiological recordings and MINFLUX nanoscopy. We show that wedge deletion and disruption of specific {pi}-{pi} and cation-{pi} interactions between the wedge 1-helix and the pore module abolishes inactivation without impairing channel activation. Moreover, MINFLUX nanoscopy reveals that the wedge stabilizes a flat inactivated conformation of PIEZO1 and suggests that wedge dissociation is required for recovery from inactivation. Together, our data support a ball-and-chain-like mechanism with the wedge acting as a state-dependent inactivation particle that docks to the pore module to terminate channel activity during sustained mechanical stimulation.

physiology↗

bioRxiv2025

3D-MINFLUX nanoscopy reveals distinct allosteric mechanisms for activation and modulation of PIEZO1 by Yoda1

PIEZO1 underpins numerous physiological processes by which cells detect and respond to mechanical stimuli. The small molecule Yoda1 has become an indispensable tool that is frequently used for dissecting the role of PIEZO1 in physiological and pathological contexts, yet its mode of action remains incompletely understood. Here, using site-directed mutagenesis, electrophysiology, computational modelling and 3D-MINFLUX nanoscopy, we demonstrate that mutation of the previously proposed Yoda1 binding site, solely abolishes Yoda1-induced activation and channel flattening but preserves modulation of mechanically-evoked PIEZO1 currents, whereas mutation of F1715, which lines a transient binding cavity accessible only in the flattened PIEZO1 conformation, eliminated modulation without affecting Yoda-induced calcium entry. Thus, our data support a two-site induced-fit-like mechanism where Yoda first engages binding site-1 to promote blade flattening and pore opening and then transitions to a deeper binding site to modulate the mechanical activation threshold and inactivation kinetics. This revised model distinguishes discrete allosteric pathways for PIEZO1 activation versus modulation and provides a framework for the design of next-generation use-dependent PIEZO1 modulators.

pharmacology and toxicology↗

bioRxiv2024

Cluster nanoarchitecture and structural diversity of PIEZO1 in intact cells

The force-gated ion channel PIEZO1 confers mechanosensitivity to many cell types. While the structure and physiological roles of PIEZO1 are well-described, the subcellular distribution and the impact of the cellular microenvironment on PIEZO1 conformation and function are poorly understood. Here, using MINFLUX nanoscopy we demonstrate that PIEZO1 channels collectively deform the membrane into pit-shaped invaginations, thereby creating mechano-responsive microdomains capable of amplifying mechanical stimuli via subtle changes in their topology. Moreover, by measuring intramolecular distances in individual PIEZO1 channels with nanometer precision, we reveal subcellular compartment-specific differences in PIEZO1 conformation at rest and during activation that correlate with differences in PIEZO1 function and are possibly caused by differences in cytoskeletal architecture. Together, our data provide previously unrecognized insights into the complex interplay of forces that determine how PIEZO1 alters membrane shape and, vice versa, how the membrane together with the cytoskeleton affect the conformation and function of individual PIEZO1 channels. TeaserMINFLUX nanoscopy reveals subcellular distribution and conformational diversity of PIEZO1 channels in intact cells.

cell biology↗

bioRxiv2022

PRE-INJURY MECHANORECEPTOR ABLATION REDUCES NOCICEPTOR-DRIVEN SPINAL CORD INJURY-INDUCED NEUROPATHIC PAIN

Evidence from previous studies supports the concept that spinal cord injury (SCI) induced neuropathic pain (NP) has its neural roots in the peripheral nervous system. There is uncertainty about how and to which degree nociceptors and mechanoreceptors contribute. Sensorimotor activation-based interventions (e.g. treadmill training) have been shown to reduce NP following experimental SCI, suggesting transmission of pain-alleviating signals through mechanoreceptors. At the same time, nociceptors have been shown to become hyperexcitable early after SCI and peptidergic axons sprout into deeper laminae of the below injury level dorsal horn. The aim of the present study is to comprehensively understand the relative contribution of each pathway in respect to NP presentation in a moderate mouse contusion SCI model. After genetic ablation of tropomyosin receptor kinase B (TrkB) expressing mechanoreceptors before SCI mechanical allodynia was reduced. The identical genetic ablation after SCI did not yield any change in pain behavior. CGRP sprouting into lamina III/IV below injury level as a consequence of SCI was not altered by either mechanoreceptor ablation. Moreover, detection of hyperexcitability in nociceptors, not in mechanoreceptors, in skin-nerve preparations of contusion SCI mice 7 days after injury makes a substantial direct contribution of mechanoreceptors to NP maintenance unlikely. SNS reporter mice allowing specific visualization of the entire nociceptor population confirmed significant sprouting of respective neurons into laminae III/IV as early as 5 days post-injury. Genetic ablation of SNS-Cre mice severely affected their overall health condition, which precluded them to undergo experimental SCI and subsequent further analysis. Complementing animal data, quantitative sensory testing in human SCI subjects indicated reduced mechanical pain thresholds, whereas the mechanical detection threshold was not altered. Taken together, early mechanoreceptor ablation modulates pain behavior, most likely through indirect mechanisms. Hyperexcitable nociceptors with consecutive peptidergic fiber sprouting in the dorsal horn are confirmed as the likely main driver of SCI-induced NP. Future studies need to focus on injury-derived factors triggering early onset nociceptor hyperexcitability, which could serve as targets for more effective therapeutic interventions.

neuroscience↗

bioRxiv2022

The molecular mechanism and physiological role of silent nociceptor activation

Silent nociceptors are sensory afferents that are insensitive to noxious mechanical stimuli under normal conditions but become sensitized to such stimuli during inflammation. Using RNA-sequencing and quantitative RT-PCR we demonstrate that inflammation selectively upregulates the expression of the transmembrane protein TMEM100 in silent nociceptors and electrophysiology revealed that over-expression of TMEM100 is required and sufficient to un-silence silent nociceptors. Moreover, we show that mice lacking TMEM100 do not develop secondary allodynia - i.e. pain hypersensitivity that spreads beyond the site of inflammation - in a mouse model of knee joint inflammation and that AAV-mediated overexpression of TMEM100 in articular afferents in the absence of inflammation is sufficient to induce allodynia in remote skin regions without causing knee joint pain. Thus, our work identifies TMEM100 as a key regulator of silent nociceptor un-silencing and reveals a physiological role for this hitherto enigmatic afferent subclass in triggering spatially remote secondary allodynia during inflammation.

neuroscience↗

bioRxiv2021

An intrinsically disordered intracellular domain of PIEZO2 is required for force-from-filament activation of the channel

A central question in mechanobiology is how mechanical forces acting in or on a cell are transmitted to mechanically-gated PIEZO channels that convert these forces into biochemical signals. Here we show that PIEZO2 is sensitive to force-transmission via the membrane (force-from-lipids) as well as force transmission via the cytoskeleton (force-from-filament) and demonstrate that the latter requires the intracellular linker between the transmembrane helices nine and ten (IDR5). Moreover, we show that rendering PIEZO2 insensitive to force-from-filament by deleting IDR5 abolishes PIEZO2-mediated inhibition of neurite outgrowth, which relies on the detection of cellgenerated traction forces, while it only partially affects its sensitivity to cell indentation and does not at all alter its sensitivity to membrane stretch. Hence, we propose that PIEZO2 is a polymodal mechanosensor that detects different types of mechanical stimuli via different force transmission pathways, which highlights the importance of utilizing multiple complementary assays when investigating PIEZO channel function.

neuroscience↗

bioRxiv2020

USH2A is a Meissner corpuscle end-organ protein necessary for vibration sensing in mice and humans

Fingertip mechanoreceptors comprise sensory neuron endings together with specialized skin cells that form the end-organ. Exquisitely sensitive vibration-sensing neurons are associated with Meissners corpuscles and Pacinian corpuscles1. Such end-organ structures have been recognized for more than 160 years, but their exact functions have remained a matter of speculation. Here we examined the role of USH2A in touch sensation in humans and mice. The USH2A gene encodes a transmembrane protein with a very large extracellular domain. Pathogenic USH2A mutations cause Usher syndrome associated with hearing loss and visual impairment2. We show that patients with biallelic pathogenic USH2A mutations also have profound impairments in vibrotactile touch perception. Similarly, mice lacking the USH2A protein showed severe deficits in a forepaw vibrotactile discrimination task. Forepaw rapidly-adapting mechanoreceptors (RAMs) recorded from Ush2a-/- mice innervating Meissners corpuscles showed profound reductions in their vibration sensitivity. However, the USH2A protein was not expressed in sensory neurons, but was found in specialized terminal Schwann cells in Meissners corpuscles. Loss of this large extracellular tether-like protein in corpuscular end-organs innervated by RAMs was sufficient to reduce the vibration sensitivity of mechanoreceptors. Thus, USH2A expressed in corpuscular end-organs associated with vibration sensing is required to properly perceive vibration. We propose that cells within the corpuscle present a tether-like protein that may link to mechanosensitive channels in sensory endings to facilitate small amplitude vibration detection essential for the perception of fine textured surfaces.

neuroscience↗

bioRxiv2020

Identification of a novel population of peripheral sensory neuron that regulates blood pressure

The vasculature is innervated by a network of peripheral afferents that sense and regulate blood flow. Here, we describe a system of non-peptidergic sensory neurons with cell bodies in the spinal ganglia that regulate vascular tone in the distal arteries. We identify a population of mechanosensitive neurons marked by TrkC and Tyrosine hydroxylase in the dorsal root ganglia that project to blood vessels. Local stimulation of these neurons decreases vessel diameter and blood flow, while systemic activation increases systolic blood pressure and heart rate variability via the sympathetic nervous system. Chemogenetic inactivation or ablation of the neurons provokes variability in local blood flow leading to a reduction in systolic blood pressure, increased heart rate variability and ultimately lethality within 48 hours. Thus, TrkC/Tyrosine hydroxylase positive sensory neurons form part of a sensory feedback mechanism that maintains cardiovascular homeostasis through the autonomic nervous system.

neuroscience↗

bioRxiv2017

Control of mechanical pain hypersensitivity through ligand-targeted photoablation of TrkB positive sensory neurons

SummaryMechanical allodynia is a major symptom of neuropathic pain whereby innocuous touch evokes severe pain. Here we identify a population of peripheral sensory neurons expressing TrkB that are both necessary and sufficient for producing pain from light touch after nerve injury. Mice in which TrkB-Cre expressing neurons are ablated are less sensitive to the lightest touch under basal conditions, and fail to develop mechanical allodynia in a model of neuropathic pain. Moreover, selective optogenetic activation of these neurons after nerve injury evokes marked nociceptive behavior. Using a phototherapeutic approach based upon BDNF, the ligand for TrkB, we perform molecule-guided laser ablation of these neurons and achieve long-term retraction of TrkB positive neurons from the skin and pronounced reversal of mechanical allodynia across multiple types of neuropathic pain. Thus we identify the peripheral neurons which transmit pain from light touch and uncover a novel pharmacological strategy for its treatment.\n\nHighlightsO_LITrkB+ neurons detect light touch under basal conditions\nC_LIO_LITrkB+ neurons convey mechanical allodynia in neuropathic pain states\nC_LIO_LIA photosensitizing derivative of BDNF allows for photoablation of TrkB+ neurons\nC_LIO_LIBDNF-guided photoablation reverses allodynia in multiple types of neuropathic pain\nC_LI

neuroscience↗