Biology subjects

Murthy, S. E.

Publications and source records attributed to Murthy, S. E..

5 recordsLinked to original sources

bioRxiv2026

PIEZOs regulate oligodendrocyte sheath formation, expansion, and myelination potential

Myelination requires precise integration of physical cues by oligodendrocyte lineage cells (OLCs), but the molecular sensors that detect these cues remain incompletely understood. Here, we demonstrate that oligodendrocyte progenitor cells (OPCs) are sensitive to sub-micron changes in membrane displacement. Based on channel properties, RNA expression, and protein abundance, we find that the mechanosensitive ion channel PIEZO1 contributes to OPC mechanosensitivity. In vivo, zebrafish with oligodendrocyte (OL)-specific disruption of piezo1 have fewer sheaths per OL. Zebrafish with OL-specific piezo2 disruption also have fewer sheaths as well as decreased total myelin capacity over time. OL-specific disruption of both piezo1 and piezo2 caused more severe phenotypes, with reduced OPC volume, and in myelinating OLs, reduced sheath number, sheath length, and total myelin output. Furthermore, piezo1/piezo2 disruption leads to sporadic sheath formation outside the normal developmental window. Our findings indicate that OLs use Piezo channels in vivo to influence sheath formation, expansion, and retractions.

neuroscience↗

bioRxiv2025

Targeting Tmem63b and Piezo2 in C-fiber low threshold mechanoreceptor: limitation of Vglut3-IRES-Cre

Peripheral somatosensory neurons in the dorsal root ganglia (DRG) transduce mechanical force in the skin and other organs into electrical signals using specialized mechanically activated (MA) ion channels that initiate neuronal activation in response to force. Increasing evidence highlights PIEZO2 as the primary transducer of low-threshold mechanical force in DRG neurons. However, in the absence of Piezo2, mice and humans still respond to noxious painful stimuli like pinch, suggesting that additional MA channel(s) likely exist in DRG neurons. Strategies to identify Cre lines and DRG subpopulations that select for non-PIEZO2 expressing neurons is therefore an ongoing effort in the field to discover unknown mechanosensors. Here, we investigated a Vglut3 labeled mouse line as a candidate to identify non-PIEZO2 MA channels in a subtype of DRG neurons called C-fiber low threshold mechanoreceptors (C-LTMRs). Our study carefully demonstrates that the Vglut3-IRES-Cre mouse line specifically and efficiently labels C-LTMR neurons of the DRG. Electrophysiological recordings using two different in vitro mechanical stimulation assays show that the genetically labelled Vglut3 neurons have robust indentation- and stretch-activated MA currents that are exclusively slowly or ultra-slowly adapting. To determine whether the Vglut3-IRES-Cre mouse line can be used to delete genes of interest and identify the underlying MA ion channels in C-LTMRs we attempted to generate a Tmem63b conditional knockout using this Cre-line but detected incomplete loss of Tmem63b transcript and lack of TMEM63B- dependent effect on C-LTMR MA currents. Together, our results emphasize that although the Vglut3-IRES-Cre line is robust in driving expression of a conditional reporter gene, it is inefficient in deleting genes like Tmem63b as well as Piezo2. Statement of SignificanceIn this study, we identify a previously uncharacterized Vglut3-IRES-Cre as a tool to uncover unknown mechanosensors in C-LTMRs of the DRG. We methodically demonstrate that the Vglut3-IRES-Cre line labels C-LTMRs and express two mechanosensors, Tmem63b and Piezo2. However, we were unable to discern which gene contributes to the MA currents due to poor knockout efficiency induced by the Vglut3-IRES-Cre. Our studies highlight the nuances and challenges associated with Cre lines and alert future investigations to exercise caution while using Cre lines to discover the contribution of specific genes to mechanosensation.

neuroscience↗

bioRxiv2024

TMEM63A, associated with hypomyelinating leukodystrophies, is an evolutionarily conserved regulator of myelination

Infantile hypomyelinating leukodystrophy 19 (HLD19) is a rare genetic disorder where patients exhibit reduced myelin in central nervous system (CNS) white matter tracts and present with varied neurological symptoms. The causative gene TMEM63A encodes a mechanosensitive ion channel whose role in myelination has not been explored. Our study shows that TMEM63A is a major regulator of OL-driven myelination in the CNS. In mouse and zebrafish, Tmem63a inactivation led to early deficits in myelination, recapitulating the HLD19 phenotype. OL-specific conditional mouse knockouts of Tmem63a exhibited transient reductions in myelin, indicating that TMEM63A regulates myelination cell-autonomously. We show that TMEM63A is present at plasma membrane and on lysosomes and modulates myelin/myelin-associated protein production. Intriguingly, HLD19-associated TMEM63A variants from patients blocked trafficking to cell membrane. Together, our results reveal an ancient role for TMEM63A in fundamental aspects of myelination in vivo and highlight two exciting new models for the development of treatments for devastating hypomyelinating leukodystrophies.

neuroscience↗

bioRxiv2021

Structural Insights into the Venus flytrap Mechanosensitive Ion Channel Flycatcher1

Flycatcher1 (FLYC1), a MscS homolog, has recently been identified as a candidate mechanosensitive (MS) ion channel involved in Venus flytrap prey recognition. FLYC1 is larger and its sequence diverges from previously studied MscS homologs, suggesting it has unique structural features that contribute to its function. Here, we characterized FLYC1 by cryo-electron microscopy, molecular dynamics simulations, and electrophysiology. Akin to bacterial MscS and plant MSL1 channels, we find that FLYC1 central core includes side portals in the cytoplasmic cage that regulate ion conduction, by identifying critical residues that modulate channel conductance. Topologically unique cytoplasmic flanking regions can adopt up or down conformations, making the channel asymmetric. Disruption of an up conformation-specific interaction severely delays channel deactivation by 40-fold likely due to stabilization of the channel open state. Our results illustrate novel structural features and likely conformational transitions that regulate mechano-gating of FLYC1.

biochemistry↗

bioRxiv2018

Cryo-EM structure of the mechanically activated ion channel OSCA1.2

Introduction Introduction Main Author Contributions Expression constructs Protein expression and... Cryo-EM sample preparation and... Cryo-EM image processing Model building and refinement Molecular dynamics simulations Generation of mutant, cell... Electrophysiology Methods Data availability References Methods References Mechanically activated (MA) ion channels underlie touch, hearing, shear-stress sensing, and response to turgor pressure1,2. Previously reported as putative ion channels sensitive to osmolality3-5, members of ...

biophysics↗