Neuron. Xiao Bailong/Li Xueming collaboration reveals the "gate plug and latch" gate dissenion mechanism of the mechanical gated Piezo ion channel.

Mechanical gated piezo ion channels are a class of important ion channels that can quickly respond to mechanical stimulation and mediate cation influx into cells, thus inducing cell excitation and signal transduction. In mammalian cells, piezo1 and piezo2 are two members (Coste et al., science 2010; Coste, Xiao et al., nature 2012).piezo1 has been found to be involved in the regulation of vascular and lymphatic vessel development, blood pressure homeostasis, bone formation and remodeling and many other functions in a variety of cell tissues, while piezo2 mediates the mechanical perception of touch, proprioception (such as posture balance perception) and visceral sense (such as lung contraction and expansion, blood pressure perception and heart rate regulation) in mammals.piezo gene mutations have been found to cause a variety of human genetic diseases, including red blood cell atrophy syndrome, lymphedema, distal joint contracture, and tactile loss.the human body carrying the piezo2 functional deletion mutation not only showed tactile and proprioceptive defects, but also lost the mechanical hypersensitivity pain perception in pathological state, which confirmed that piezo2 channel can be an important target for the development of new analgesic drugs.in recent years, the research group of Dr. Xiao Bailong of Tsinghua University has comprehensively used the biochemical structure, electrophysiological patch clamp, high-throughput drug screening, transgenic mouse model and human genetics and other multidisciplinary research methods, focusing on how the mechanically gated piezo channel converts mechanical stimulation into electrochemical signal, and how it uses its own mechanical sensitivity and channel characteristics to determine the correlation We are committed to developing new drugs and technologies targeting piezo channel.three dimensional structure analysis of piezo channel so far (nature 2015, In this study, we analyzed the molecular mechanism (neuron 2016; nature communications 2017), discovery of small molecule drugs (nature communications 2018), and exploration of physiological and pathological functions (cell reports 2019; eLife 2019) (see bioart report: cell report for details)| During the Spring Festival, a series of important research achievements have been made in the following aspects: first, a series of important research achievements have been made in the aspects of eLife Li Yingxian / Xiao Bailong's cooperation in revealing the new mechanism of bone tissue sensing mechanical signals.Dr. Xiao Bailong was invited to write an annual review of 2020 annual review of pharmacology and Toxicology (2020 Jan 6; 60:195-218), which systematically introduced the important research progress of piezo channel in recent 10 years and its important prospects and strategies as a new drug target for drug development.the project team of Xiao Bailong and Li Xueming worked together in 2018 and 2019| In nature, the trefoil helix structure and working mechanism of full-length piezo1 and piezo2 were reported in the journal Nature by Xiao Bailong / Li Xueming cooperation group of Tsinghua University. It was revealed that they assembled into a large membrane protein complex containing the most transmembrane helix region in a total of 114 times by trimers The unique structural basis provides accurate parameters for the analysis of the thermodynamic process of the channel opening caused by mechanical force stimulation, and innovatively puts forward the leverage mechanism hypothesis and double gate mechanism hypothesis of the mechanical gating.they believe that there are two switch gates in the ion permeability path of piezo channel, in which the switch gate in the transmembrane region is controlled by the rotation of the extracellular cap area directly above the channel, while the switch gate in the cytoplasmic region may be controlled by the similar leverage principle through the paddle blade and the long rod structure inside the cell (Fig. a).however, the exact ion permeability pathway, gate switching site and gating mechanism of piezo channel are not clear.on March 5, 2020, a plug-and-latch mechanism for gating the mechanosensitive piezo was published by Xiao Bailong, School of pharmacy, Tsinghua University, and Li Xueming, School of life In this paper, a novel piezo 1 shear variant subtype with mechanical hypersensitivity due to the absence of "gate" structural elements was identified.the research results not only greatly promote our understanding of how mechanical force stimulation can be transformed into electrochemical signals, but also help to modify and intervene the functional properties of piezo channels, and lay a foundation for the final realization of biotechnology development, drug discovery and disease treatment based on piezo pathway.in the latest neuron paper, three lateral ion permeability pathways in the inner side of piezo channel were determined by using site directed mutagenesis based on structural analysis, electrophysiological function of patch clamp and identification of novel shear variants Portal), lateral plug gate (lateral plug gate) that physically blocks the lateral ion permeability path, and latch element (latch) that controls the lateral plug (Fig. a).combined with the functional research of these key elements, they obtained a series of experimental data to help them put forward for the first time the ingenious molecular mechanism of piezo channel using these key functional elements to regulate the closing and opening of lateral ion permeability pathway in a physical way similar to "plug and latch".first of all, structural analysis suggested that there might be two possible ion permeability pathways in the inner side of piezo channel (Fig. a).through site directed mutagenesis of 9 amino acid sites in the lateral ion permeability pathway, the cation selective piezo1 channel was completely transformed into an anion selective channel.however, the mutation of amino acids in the vertical direction did not change the ion selectivity. these results support that the piezo1 channel uses three intracellular lateral portals to transport cations. secondly, through structural analysis, they found that the openings of the three lateral pathways were physically blocked by an amino acid sequence (Fig. a). electrophysiological study found that if the amino acids were removed, the single channel conductance and mechanical sensitivity would be significantly increased, and the calcium ion permeability would also be changed. based on these structural and functional analysis results, they proposed that this amino acid sequence forms a lateral plug gate to regulate the opening and closing of the lateral ion permeability pathway. interestingly, the researchers identified a novel piezo1 shear variant that was expressed in a variety of cell tissues. The missing segment of the piezo1 splicing variant just contained the lateral plug structure sequence. They named this splice variant piezo1.1 (Fig. b). electrophysiological study showed that piezo1.1 shear mutant had higher single channel conductance and more sensitive mechanical sensitivity than the mutant without lateral plug structure sequence. piezo1.1 is a member of piezo channel family which is most sensitive to mechanical force. to their surprise, they further found that a splicing variant of piezo2 just missed the conserved sequence of lateral gate structure, suggesting that both piezo1 and piezo2 genes regulate the key domain of lateral gating by selective splicing to regulate the channel properties. schematic diagram of "plug and latch" gating mechanism of mechanical gated piezo ion channel (a) schematic diagram of key structural elements of piezo channel. (b) when piezo is open, the tmgate can be opened by the rotating motion of the cap structure element directly above it, and the lateral plug element may be partially opened by the mechanical force transmitted by the blade beam structure element in a way similar to pulling the door plug, resulting in the cation flow in the lateral ion permeability path. (C-E) when the lateral plug is removed (c) or the gate is not coordinated due to sudden change (D, e), the change of the gate control mode of the lateral plug leads to the change of channel characteristics. the red dotted line and the red solid line in the figure represent the closing and opening of the ion permeability pathway respectively. in order to prove that the functional change of piezo1.1 shear variant is caused by the absence of lateral plug structure, they analyzed the three-dimensional structure of piezo1.1 shear variant under freeze electron microscope. consistent with their hypothesis, the piezo1.1 shear variant lacks the lateral plug structure, resulting in a fully open opening of the lateral ion permeability path. the researchers further explored how the three lateral ion permeability pathways are regulated by three lateral plugs. structural analysis found that three lateral plug structures were anchored to the central axis of piezo1 channel cell by the structure sequence located in the front and rear segments, forming a latch like structure to control the three plug structures in coordination (Fig. a). single channel recording found that the mutation that destroyed piezo1 assembly resulted in subconductance opening. Interestingly, the size of subconductance was exactly one-third of the total conductance, indicating that the three permeability pathways were open in a quantized rather than synergistic manner (Fig. C, d). the above studies reveal the fine structure and assembly mode of piezo channel, as well as the delicate mechanism of mechanical gating, as well as the subtle regulation of this structure and mechanism by natural evolution. it is reported that Dr. Xiao Bailong and Dr. Li Xueming, School of pharmacy, Tsinghua University are co authors of this paper. Geng Jie, postdoctoral student of School of pharmacy, Tsinghua University (now working in Beijing University of traditional Chinese Medicine), Liu Wenhao, 2016 doctoral student, Zhou Heng, 2015 doctoral student, Xiao Bailong research group, Dr. Zhang Tingxin (now postdoctoral of MD Anderson Cancer Center in the United States), and Wang Li, postdoctoral student of pharmaceutical college, are the first author in parallel. in addition, Dr. Zhang Mingmin (now a postdoctoral student of the University of Michigan) of Xiao Bailong's research group, Li Jianran, a doctoral student, and Shen Pu of the Li Xueming research group also participated in part of the work. postdoctoral recruitment: Dr. Xiao Bailong's laboratory recruits excellent postdoctors with neuroscience, physiology and ion channel research background all year round. please contact: xbailong@mail.tsinghua.edu.cn Link to the original text: