Worms find PEZO-1’s function easy to swallow

JGP study finds that the C. elegans orthologue of the PIEZO family is a mechanosensitive ion channel that regulates pharyngeal pumping and food sensation.

C. elegans PEZO-1 is a mechanosensitive ion channel involved in food sensation

PIEZO channels are force sensors essential for physiological processes, including baroreception and proprioception. The Caenorhabditis elegans genome encodes an orthologue gene of the Piezo family, pezo-1, which is expressed in several tissues, including the pharynx. This myogenic pump is an essential component of the C. elegans alimentary canal, whose contraction and relaxation are modulated by mechanical stimulation elicited by food content. Whether pezo-1 encodes a mechanosensitive ion channel and contributes to pharyngeal function remains unknown. Here, we leverage genome editing, genetics, microfluidics, and electropharyngeogram recording to establish that pezo-1 is expressed in the pharynx, including in a proprioceptive-like neuron, and regulates pharyngeal function. Knockout (KO) and gain-of-function (GOF) mutants reveal that pezo-1 is involved in fine-tuning pharyngeal pumping frequency, as well as sensing osmolarity and food mechanical properties. Using pressure-clamp experiments in primary C. elegans embryo cultures, we determine that pezo-1 KO cells do not display mechanosensitive currents, whereas cells expressing wild-type or GOF PEZO-1 exhibit mechanosensitivity. Moreover, infecting the Spodoptera frugiperda cell line with a baculovirus containing the G-isoform of pezo-1 (among the longest isoforms) demonstrates that pezo-1 encodes a mechanosensitive channel. Our findings reveal that pezo-1 is a mechanosensitive ion channel that regulates food sensation in worms.

The mechanosensitive channel Piezo1 cooperates with Semaphorin to control neural crest migration

Cells are permanently exposed to a multitude of different kind of signals; however how cells respond to simultaneous extracellular signals within a complex in vivo environment is poorly understood. Here, we studied the role of the mechanosensitive ion channel Piezo1 on the migration of the neural crest (NC), a multipotent embryonic cell population. We identify that Piezo1 is required for the migration of Xenopus cephalic NC. We show that loss of Piezo1 promotes focal adhesion turnover and cytoskeletal dynamics by controlling Rac1 activity, leading to increased speed of migration. Moreover, overactivation of Rac1, due to Piezo1 inhibition, counteracts cell migration inhibitory signals by Semaphorins 3A and 3F, generating aberrant neural crest invasion in vivo. Thus, we find that, for directional migration in vivo, neural crest cells require a tight regulation of Rac1, by Semaphorins and Piezo1. We reveal here that a balance between a myriad of signals through Rac1 dictates cell migration in vivo, a mechanism that is likely to be conserved in other cell migration processes.

The Mechanosensitive Ion Channel MSL10 Modulates Susceptibility to Pseudomonas syringae in Arabidopsis thaliana

Plants sense and respond to molecular signals associated with the presence of pathogens and their virulence factors. Mechanical signals generated during pathogenic invasion may also be important, but their contributions have rarely been studied. Here we investigate the potential role of a mechanosensitive ion channel, MscS-Like (MSL)10, in defense against the bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana. We previously showed that overexpression of MSL10-GFP, phospho-mimetic versions of MSL10, and the gain-of-function allele msl10-3G all produce dwarfing, spontaneous cell death, and the hyperaccumulation of reactive oxygen species. These phenotypes are shared by many autoimmune mutants and are frequently suppressed by growth at high temperature in those lines. Here, we found that the same was true for all three MSL10 hypermorphs. In addition, we show that the SGT1/RAR1/HSP90 co-chaperone complex was required for dwarfing and ectopic cell death, PAD4 and SID2 were partially required, and the immune regulators EDS1 and NDR1 were dispensable. All MSL10 hypermorphs exhibited reduced susceptibility to infection by P. syringae strain Pto DC3000, Pto DC3000 expressing the avirulence genes avrRpt2 or avrRpm1, but not Pto DC3000 hrpL, and showed an accelerated induction of PR1 expression compared to wild-type plants. Null msl10-1 mutants were delayed in PR1 induction and displayed modest susceptibility to infection by COR-deficient Pst. Finally, stomatal closure was reduced in msl10-1 loss-of-function mutants in response to Pst COR−. These data show that MSL10 modulates pathogen responses and begin to address the possibility that mechanical signals are exploited by the plant for pathogen perception.

Cryo-electron microscopy revealed TACAN is extensively and specifically associated with membrane lipids

TACAN is not a mechanosensitive ion channel but significantly linked to the mechanical hyperalgesia. In this study, we show that the human TACAN is a homodimer with each monomer consisting of a body, a spring and a blade domains. The body domain contains six transmembrane helices that forms an independent channel. The spring domain adapts a loop-helix-loop configuration with the helix running within and parallel to the membrane. The blade domain is composed of two cytoplasmic helices. In addition, we found that all the helices of the body and the spring domains are specifically associated with membrane lipids. Particularly, a lipid core, residing within a cavity formed by the two body and spring domains, contacts with the helices from the body and spring domains and extends to reach two symmetrically arranged lipid clusters. These results extremely imply that the membrane lipids coordinate with the membrane-embedded protein to sense and transduce the mechanic signal.

The Mechanosensitive Ion Channel MSL10 Modulates Susceptibility to Pseudomonas syringae in Arabidopsis thaliana

Plants sense and respond to molecular signals associated with the presence of pathogens and their virulence factors. Mechanical signals generated during pathogenic invasion may also be important, but their contributions have rarely been studied. Here we investigate the potential role of a mechanosensitive ion channel, MscS-Like (MSL)10, in defense against the bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana. We previously showed that overexpression of MSL10-GFP, phospho-mimetic versions of MSL10, and the gain-of-function allele msl10-3G all produce dwarfing, spontaneous cell death, and the hyperaccumulation of reactive oxygen species. These phenotypes are shared by many autoimmune mutants and are frequently suppressed by growth at high temperature in those lines. Here, we found that the same was true for all three MSL10 hypermorphs. In addition, we show that the SGT1/RAR1/HSP90 co-chaperone complex was required for dwarfing and ectopic cell death, PAD4 and SID2 were partially required, and the immune regulators EDS1 and NDR1 were dispensable. All MSL10 hypermorphs exhibited reduced susceptibility to infection by P. syringae strain Pto DC3000, Pto DC3000 expressing the avirulence genes avrRpt2 or avrRpm1, but not Pto DC3000 hrpL, and showed an accelerated induction of PR1 expression compared to wild-type plants. Null msl10-1 mutants were delayed in PR1 induction and displayed modest susceptibility to infection by COR-deficient Pst. Finally, stomatal closure was reduced in msl10-1 loss-of-function mutants in response to Pst COR−. These data show that MSL10 modulates pathogen responses and begin to address the possibility that mechanical signals are exploited by the plant for pathogen perception.

Analysis of the Mechanosensor Channel Functionality of TACAN

Mechanosensitive ion channels mediate transmembrane ion currents activated by mechanical forces. A mechanosensitive ion channel called TACAN was recently reported. We began to study TACAN with the intent to understand how it senses mechanical forces and functions as an ion channel. Using cellular patch-recording methods we failed to identify mechanosensitive ion channel activity. Using membrane reconstitution methods we found that TACAN, at high protein concentrations, produces heterogeneous conduction levels that are not mechanosensitive and are most consistent with disruptions of the lipid bilayer. We determined the structure of TACAN using single particle cryo-EM and observe that it forms a symmetrical dimeric transmembrane protein. Each protomer contains an intracellular-facing cleft with a coenzyme-A cofactor, confirmed by mass spectrometry. The TACAN protomers are related in 3-dimensional structure to a fatty acid elongase, ELOVL. Whilst its physiological function remains unclear, we anticipate that TACAN is not a mechanosensitive ion channel.

Piezo1-Mediated Mechanotransduction Promotes Cardiac Hypertrophy by Impairing Calcium Homeostasis to Activate Calpain/Calcineurin Signaling

Hemodynamic overload induces pathological cardiac hypertrophy, which is an independent risk factor for intractable heart failure in long run. Beyond neurohumoral regulation, mechanotransduction has been recently recognized as a major regulator of cardiac hypertrophy under a myriad of conditions. However, the identification and molecular features of mechanotransducer on cardiomyocytes are largely sparse. For the first time, we identified Piezo1 (Piezo type mechanosensitive ion channel component 1), a novel mechanosensitive ion channel with preference to Ca 2+ was remarkably upregulated under pressure overload and enriched near T-tubule and intercalated disc of cardiomyocyte. By applying cardiac conditional Piezo1 knockout mice (Piezo1 fl/fl Myh6Cre+, Piezo1 Cko ) undergoing transverse aortic constriction, we demonstrated that Piezo1 was required for the development of cardiac hypertrophy and subsequent adverse remodeling. Activation of Piezo1 by external mechanical stretch or agonist Yoda1 lead to the enlargement of cardiomyocytes in vitro, which was blocked by Piezo1 silencing or Yoda1 analog Dooku1 or Piezo1 inhibitor GsMTx4. Mechanistically, Piezo1 perturbed calcium homeostasis, mediating extracellular Ca 2+ influx and intracellular Ca 2+ overload, thereby increased the activation of Ca 2+ -dependent signaling, calcineurin, and calpain. Inhibition of calcineurin or calpain could abolished Yoda1 induced upregulation of hypertrophy markers and the hypertrophic growth of cardiomyocytes in vitro. From a comprehensive view of the cardiac transcriptome, most of Piezo1 affected genes were highly enriched in muscle cell physiology, tight junction, and corresponding signaling. This study characterizes an undefined role of Piezo1 in pressure overload induced cardiac hypertrophy. It may partially decipher the differential role of calcium under pathophysiological condition, implying a promising therapeutic target for cardiac dysfunction.