Electron cryo-microscopy structure of the mechanotransduction channel NOMPC.

Mechanosensory transduction for senses such as proprioception, touch, balance, acceleration, hearing and pain relies on mechanotransduction channels, which convert mechanical stimuli into electrical signals in specialized sensory cells. How force gates mechanotransduction channels is a central question in the field, for which there are two major models. One is the membrane-tension model: force applied to the membrane generates a change in membrane tension that is sufficient to gate the channel, as in the bacterial MscL channel and certain eukaryotic potassium channels. The other is the tether model: force is transmitted via a tether to gate the channel. The transient receptor potential (TRP) channel NOMPC is important for mechanosensation-related behaviours such as locomotion, touch and sound sensation across different species including Caenorhabditis elegans, Drosophila and zebrafish. NOMPC is the founding member of the TRPN subfamily, and is thought to be gated by tethering of its ankyrin repeat domain to microtubules of the cytoskeleton. Thus, a goal of studying NOMPC is to reveal the underlying mechanism of force-induced gating, which could serve as a paradigm of the tether model. NOMPC fulfils all the criteria that apply to mechanotransduction channels and has 29 ankyrin repeats, the largest number among TRP channels. A key question is how the long ankyrin repeat domain is organized as a tether that can trigger channel gating. Here we present a de novo atomic structure of Drosophila NOMPC determined by single-particle electron cryo-microscopy. Structural analysis suggests that the ankyrin repeat domain of NOMPC resembles a helical spring, suggesting its role of linking mechanical displacement of the cytoskeleton to the opening of the channel. The NOMPC architecture underscores the basis of translating mechanical force into an electrical signal within a cell.

Enhanced Photocatalytic Coupling of Benzylamine to N-Benzylidene Benzylamine over the Organic-Inorganic Composites F70-TiO2 Based on Fullerenes Derivatives and TiO2.

The organic-inorganic composites F70-TiO2, based on fullerene with carboxyl group derivatives and TiO2 semiconductor, have been designed and constructed to become an optical-functional photocatalyst via the facile sol-gel method. The composite photocatalyst obtained shows excellent photocatalytic activity for the high-efficiency conversion of benzylamine (BA) to N-benzylidene benzylamine (NBBA) with air pressure at a normal temperature under visible light irradiation. By optimizing the composition, the composites with the 1:15 mass ratio of F70 and TiO2, denoted as F70-TiO2(1:15), demonstrated the highest reaction efficiency for benzylamine (>98% conversion) to N-benzylidene benzylamine (>93% selectivity) in this study. However, pure TiO2 and fullerene derivatives (F70) exhibit decreased conversion (56.3% and 89.7%, respectively) and selectivity (83.8% and 86.0%, respectively). The UV-vis diffuse reflectance spectra (DRS) and Mott-Schottky experiment's results indicate that the introduction of fullerene derivatives into anatase TiO2 would greatly broaden the visible light response range and adjust the energy band positions of the composites, enhancing the sunlight utilization and promoting the photogenerated charge (e--h+) separation and transfer. Specifically, a series of results on the in situ EPR tests and the photo-electrophysical experiment indicate that the separated charges from the hybrid could effectively activate benzylamine and O2 to accelerate the formation of active intermediates, and then couple with free BA molecules to form the desired production of N-BBA. The effective combination, on a molecular scale, between fullerene and titanium dioxide has provided a profound understanding of the photocatalysis mechanism. This work elaborates and makes clear the relationship between the structure and the performance of functional photocatalysts.

[Medication rules of Chinese herbal compound prescriptions for treating angina in national patent database based on multiple data mining].

This study explored the medication rules of Chinese herbal compound prescriptions for the treatment of angina based on the Chinese herbal compound patents in the patent database of the China National Intellectual Property Administration. The data of eligible Chinese herbal compound patents for the treatment of angina were collected from the patent database of the China National Intellectual Property Administration from database inception to November 10, 2022, and subjected to data modeling, analysis of main syndromes, medication frequency analysis, cluster analysis, association rule analysis, and data visualization by using Excel 2021, IBM SPSS Statistics 26.0, IBM SPSS Modeler 18.0, Cytoscape 3.9.1, and Rstudio R 4.2.2.2 to explore the medication rules for angina. The study included 636 pieces of patent data for angina that met the inclusion criteria, involving 815 drugs, with a total frequency of 6 586. The most common main syndromes were blood stasis obstructing the heart syndrome(222, 34.91%) and Qi deficiency and blood stasis syndrome(112, 17.61%). The top 10 most frequently used drugs were Salviae Miltiorrhizae Radix et Rhizoma, Chuanxiong Rhizoma, Notoginseng Radix et Rhizoma, Astragali Radix, Angelicae Sinensis Radix, Carthami Flos, Glycyrrhizae Radix et Rhizoma, Ginseng Radix et Rhizoma, Borneolum Syntheticum, and Corydalis Rhizoma. High-frequency drugs included blood-activating and stasis-resolving drugs(1 197, 18.17%) and deficiency-tonifying drugs(809, 12.28%). Cluster analysis identified eight drug combinations, including five new prescriptions suitable for clinical use and new drug development, and three drug pairs. The core drug combination of Salviae Miltiorrhizae Radix et Rhizoma-Chuanxiong Rhizoma-Carthami Flos was identified through the complex co-occurrence network analysis of Chinese medicines. Association rule analysis yielded a total of 17 rules, including 13 drug pairs and 4 tripartite combinations. Common drug pairs included Salviae Miltiorrhizae Radix et Rhizoma-Chuanxiong Rhizoma(support degree 25.79%, confidence coefficient 69.49%, lift 1.30) and Salviae Miltiorrhizae Radix et Rhizoma-Notoginseng Radix et Rhizoma(support degree 22.01%, confidence coefficient 61.95%, lift 1.16). Common tripartite combinations included Salviae Miltiorrhizae Radix et Rhizoma-Chuanxiong Rhizoma-Astragali Radix(support degree 10.85%, confidence coefficient 73.40%, lift 1.37) and Salviae Miltiorrhizae Radix et Rhizoma-Chuanxiong Rhizoma-Notoginseng Radix et Rhizoma(support degree 10.69%, confidence coefficient 79.07%, lift 1.48). The results showed that the underlying pathogenesis of angina involved blood stasis obstructing the heart and Qi deficiency and blood stasis. The overall nature of the disease was characterized as asthenia in origin and sthenia in superficiality. In the prescription formulation, blood-activating and stasis-resolving drugs, such as Salviae Miltiorrhizae Radix et Rhizoma, Chuanxiong Rhizoma, and Carthami Flos were often used to resolve the excess manifestation, which were combined with tonifying drugs such as Astragali Radix, Angelicae Sinensis Radix, Glycyrrhizae Radix et Rhizoma, and Ginseng Radix et Rhizoma to reinforce the deficiency. The syndrome, pathogenesis, disease nature, and medication were consistent with clinical practice. Additionally, the new compound prescriptions and drug combinations derived from the multiple data mining in this study could provide references and insights for the clinical diagnosis and treatment of angina and the development of new drugs.

Transmembrane channel-like (tmc) gene regulates Drosophila larval locomotion.

Drosophila larval locomotion, which entails rhythmic body contractions, is controlled by sensory feedback from proprioceptors. The molecular mechanisms mediating this feedback are little understood. By using genetic knock-in and immunostaining, we found that the Drosophila melanogaster transmembrane channel-like (tmc) gene is expressed in the larval class I and class II dendritic arborization (da) neurons and bipolar dendrite (bd) neurons, both of which are known to provide sensory feedback for larval locomotion. Larvae with knockdown or loss of tmc function displayed reduced crawling speeds, increased head cast frequencies, and enhanced backward locomotion. Expressing Drosophila TMC or mammalian TMC1 and/or TMC2 in the tmc-positive neurons rescued these mutant phenotypes. Bending of the larval body activated the tmc-positive neurons, and in tmc mutants this bending response was impaired. This implicates TMC's roles in Drosophila proprioception and the sensory control of larval locomotion. It also provides evidence for a functional conservation between Drosophila and mammalian TMCs.

Drosophila TMEM63 and mouse TMEM63A are lysosomal mechanosensory ion channels.

Cells sense physical forces and convert them into electrical or chemical signals, a process known as mechanotransduction. Whereas extensive studies focus on mechanotransduction at the plasma membrane, little is known about whether and how intracellular organelles sense mechanical force and the physiological functions of organellar mechanosensing. Here we identify the Drosophila TMEM63 (DmTMEM63) ion channel as an intrinsic mechanosensor of the lysosome, a major degradative organelle. Endogenous DmTMEM63 proteins localize to lysosomes, mediate lysosomal mechanosensitivity and modulate lysosomal morphology and function. Tmem63 mutant flies exhibit impaired lysosomal degradation, synaptic loss, progressive motor deficits and early death, with some of these mutant phenotypes recapitulating symptoms of TMEM63-associated human diseases. Importantly, mouse TMEM63A mediates lysosomal mechanosensitivity in Neuro-2a cells, indicative of functional conservation in mammals. Our findings reveal DmTMEM63 channel function in lysosomes and its physiological roles in vivo and provide a molecular basis to explore the mechanosensitive process in subcellular organelles.

Phospholipid Homeostasis Regulates Dendrite Morphogenesis in Drosophila Sensory Neurons.

Disruptions in lipid homeostasis have been observed in many neurodevelopmental disorders that are associated with dendrite morphogenesis defects. However, the molecular mechanisms of how lipid homeostasis affects dendrite morphogenesis are unclear. We find that easily shocked (eas), which encodes a kinase with a critical role in phospholipid phosphatidylethanolamine (PE) synthesis, and two other enzymes in this synthesis pathway are required cell autonomously in sensory neurons for dendrite growth and stability. Furthermore, we show that the level of Sterol Regulatory Element-Binding Protein (SREBP) activity is important for dendrite development. SREBP activity increases in eas mutants, and decreasing the level of SREBP and its transcriptional targets in eas mutants largely suppresses the dendrite growth defects. Furthermore, reducing Ca2+ influx in neurons of eas mutants ameliorates the dendrite morphogenesis defects. Our study uncovers a role for EAS kinase and reveals the in vivo function of phospholipid homeostasis in dendrite morphogenesis.

The role of PPK26 in Drosophila larval mechanical nociception.

In Drosophila larvae, the class IV dendritic arborization (da) neurons are polymodal nociceptors. Here, we show that ppk26 (CG8546) plays an important role in mechanical nociception in class IV da neurons. Our immunohistochemical and functional results demonstrate that ppk26 is specifically expressed in class IV da neurons. Larvae with mutant ppk26 showed severe behavioral defects in a mechanical nociception behavioral test but responded to noxious heat stimuli comparably to wild-type larvae. In addition, functional studies suggest that ppk26 and ppk (also called ppk1) function in the same pathway, whereas piezo functions in a parallel pathway. Consistent with these functional results, we found that PPK and PPK26 are interdependent on each other for their cell surface localization. Our work indicates that PPK26 and PPK might form heteromeric DEG/ENaC channels that are essential for mechanotransduction in class IV da neurons.

Drosophila TRPA channel painless inhibits male-male courtship behavior through modulating olfactory sensation.

The Drosophila melanogaster TRPA family member painless, expressed in a subset of multidendritic neurons embeding in the larval epidermis, is necessary for larval nociception of noxious heat or mechanical stimuli. However, the function of painless in adult flies remains largely unknown. Here we report that mutation of painless leads to a defect in male-male courtship behavior and alteration in olfaction sensitivity in adult flies. Specific downregulation of the expression of the Painless protein in the olfactory projection neurons (PNs) of the antennal lobes (ALs) resulted in a phenotype resembling that found in painless mutant flies, whereas overexpression of Painless in PNs of painless mutant males suppressed male-male courtship behavior. The downregulation of Painless exclusively during adulthood also resulted in male-male courtship behavior. In addition, mutation of the painless gene in flies caused changes in olfaction, suggesting a role for this gene in olfactory processing. These results indicate that functions of painless in the adult central nervous system of Drosophila include modulation of olfactory processing and inhibition of male-male courtship behavior.

Precise spatiotemporal control of optogenetic activation using an acousto-optic device.

Light activation and inactivation of neurons by optogenetic techniques has emerged as an important tool for studying neural circuit function. To achieve a high resolution, new methods are being developed to selectively manipulate the activity of individual neurons. Here, we report that the combination of an acousto-optic device (AOD) and single-photon laser was used to achieve rapid and precise spatiotemporal control of light stimulation at multiple points in a neural circuit with millisecond time resolution. The performance of this system in activating ChIEF expressed on HEK 293 cells as well as cultured neurons was first evaluated, and the laser stimulation patterns were optimized. Next, the spatiotemporally selective manipulation of multiple neurons was achieved in a precise manner. Finally, we demonstrated the versatility of this high-resolution method in dissecting neural circuits both in the mouse cortical slice and the Drosophila brain in vivo. Taken together, our results show that the combination of AOD-assisted laser stimulation and optogenetic tools provides a flexible solution for manipulating neuronal activity at high efficiency and with high temporal precision.