Spontaneous signal generation by an excitable system for cell migration.

Eukaryotic cells exhibit random migration in the absence of extracellular directional cues. This random migration acts as basal motility for various migratory responses such as chemotaxis. The self-organization of random motility requires the internal signals that determine the anterior side of the migrating cell be generated spontaneously from the intrinsic activities of intracellular signaling networks. Recent studies have identified an excitable system as the mechanism of the spontaneous signal generation. Here, we discuss how the excitable system of Ras, a small G protein, regulates signaling networks in Dictyostelium discoideum as a model organism. The excitability produces a domain where an active form of Ras is enriched on the cell membrane without extracellular directional cues, such that Ras serves as the anterior signal. The typical spatiotemporal characteristics are mathematically explained by reaction-diffusion models. These models further enable a quantitative analysis of the dynamics that depends on the internal cellular states and surrounding environments. Downstream of the Ras excitable system, a phosphoinositide metabolic network composed of PI3K, PTEN, PI(3,4,5)P3 and PI(4,5)P2 exhibits bistability to discretize the anterior and posterior regions of the cell membrane. Upstream, a local excitation and global inhibition local excitation global inhibition network, which works for gradient sensing in the presence of chemoattractant gradients, spatiotemporally biases the excitability of Ras for chemotaxis. In parallel with the Ras excitable system, the cGMP signaling pathway constitutes another excitable system of its own periodicity to ensure flexible migratory dynamics. In addition to these intracellular signaling networks, an intercellular signaling network activated by secreted cAMP is coupled with the Ras excitable system for collective cell migration. Finally, we discuss how the excitable system of Ras operates as a platform of information integration by receiving multiple intrinsic and extrinsic signals to ensure spontaneous cellular activity and robust responses in eukaryotic cell migration under natural complex environments.

Left-right Myosin-Is, Myosin1C, and Myosin1D exhibit distinct single molecule behaviors on the plasma membrane of Drosophila macrophages.

Left-right (LR) asymmetry is crucial for animal development, particularly in Drosophila where LR-asymmetric morphogenesis of organs hinges on cellular-level chirality, termed cell chirality. In this species, two class I myosins, Myosin1D (Myo1D), and Myosin1C (Myo1C), respectively determine dextral (wild type) and sinistral (mirror image) cell chirality. Previous studies demonstrated Myo1D's ability to propel F-actin in leftward circles during in vitro gliding assays, suggesting its mechanochemical role in defining dextral chirality. Conversely, Myo1C propels F-actin without exhibiting LR-directional preference in this assay, suggesting at other properties governing sinistral chirality. Given the interaction of Myo1D and Myo1C with the membrane, we hypothesized that differences in their membrane behaviors might be critical in dictating their dextral or sinistral activities. In this study, employing single-molecule imaging analyses, we investigated the dynamic behaviors of Myo1D and Myo1C on the plasma membrane. Our findings revealed that Myo1C exhibits a significantly greater proportion of slow-diffusing population compared to Myo1D. Importantly, this characteristic was contingent upon both head and tail domains of Myo1C. The distinct diffusion patterns of Myo1D and Myo1C did not exert mutual influence on each other. This divergence in membrane diffusion between Myo1D and Myo1C may be crucial for dictating cell and organ chirality.

[Validation of the Qualitative Study Findings using Quantitative Analyses on the Current Status of Pharmacists in Home Health Care in Medium-Sized Areas].

Although the issue of home medical care and pharmacists remains widespread, much of the discussion has concentrated on its state in urban areas. We believe that it is necessary to consider the state of home health care in medium-sized regions, that is separate from its urban form, with a population of approximately 100000. Thus, we conducted a qualitative study in Hikone City, Shiga Prefecture, to identify factors that impede pharmacists involved in home medical care. We conducted a questionnaire-based survey in an area of the same size to verify the generality of the concepts obtained from the qualitative study and validate the concepts using quantitative analyses. Two questionnaires on the role of community health care and home health care practice based on the concepts obtained from the qualitative study was sent to 342 pharmacies located in five regions. The number of valid responses was 170, and the data collection rate was 49.4%. We identified nine factors from the former and five from the latter. The current status of pharmacists in home health care in a medium-sized region, as identified by the quantitative study, was similar to that of the conceptual picture obtained from the qualitative study. Furthermore, the high versatility of the extracted concepts was verified.

Cholesterol suppresses spontaneous activation of EGFR-mediated signal transduction.

Epidermal growth factor receptor (EGFR)-mediated signal transduction controls cell growth and proliferation. The signaling pathway is regulated so that it is activated only by external EGF stimuli, but the mechanisms that prevent EGF-independent spontaneous activation of EGFR-mediated signaling are unknown. Here we report cholesterol depletion activates EGFR-mediated signaling without EGF. We applied automated single-molecule imaging to EGFR and characterized the lateral diffusion and cluster formation on cholesterol-depleted and cholesterol-supplemented membranes. In cells in which cholesterol was depleted by methyl-ß-cyclodextrin (MßCD) treatment, EGFR exhibited a reduction in lateral diffusion, an acceleration of cluster formation, and autophosphorylation without EGF. Concurrently, extracellular signal-regulated kinase (ERK), which is regulated by EGFR-mediated signaling, exhibited phosphorylation and nuclear translocation without EGF. These cholesterol depletion-induced changes were similar, albeit less efficient, to those that occurred with EGF stimulation in normal cells without MßCD, indicating the spontaneous activation of EGFR signaling. The exogenous supplementation of cholesterol suppressed the MßCD-induced spontaneous activation of EGFR and ERK nuclear translocation. Single-molecule imaging of EGFR in a large number of cells revealed cell-to-cell heterogeneity, with a sub-population showing a high ability for spontaneous activation. These results provide evidence that EGFR-mediated signaling is properly regulated by cholesterol metabolism to prevent uncontrolled spontaneous activation.

Sulfamethoxazole-trimethoprim for pneumocystis pneumonia prophylaxis, causes of discontinuation and thrombocytopenia observed during administration: A single-center retrospective study.

INTRODUCTION: The development of pneumocystis pneumonia (PCP) has recently become a growing concern; thus, its prevention has become increasingly important. Sulfamethoxazole-trimethoprim (ST) is a cost-effective first-line and prophylactic treatment for PCP. However, ST administration criteria for PCP prophylaxis remain unclear and are often discontinued because of adverse events (AEs). In this study, we aimed to investigate the causes of ST discontinuation and the associated AEs using objective data. METHODS: We retrospectively analyzed the data of 162 patients admitted to Kansai Medical University Hospital between January 2018 and December 2020, who received ST for PCP prophylaxis. We compared clinical characteristics, laboratory data, and incidence of AEs between ST non-discontinuation and ST discontinuation groups. Additionally, we divided the patients into non-developing and developing thrombocytopenia (≥ Grade 1) groups based on the investigation results. RESULTS: No patients developed PCP while receiving ST. The most common causes of ST discontinuation were thrombocytopenia (37%), liver dysfunction (20%), and rash (18%). Multivariate analysis revealed thrombocytopenia (≥ Grade 1) as a factor significantly associated with ST discontinuation. Furthermore, we identified three factors correlated with thrombocytopenia (≥ Grade 1): age ≥50 years, lymphocyte count <1000/µL, and platelet count <180,000/µL. CONCLUSIONS: Patients with the aforementioned factors are at higher risk of developing thrombocytopenia (≥ Grade 1) during ST administration for PCP prophylaxis. Therefore, platelet count monitoring is essential to enhance safety and efficacy of ST treatment. Nonetheless, further research is warranted to explore additional implications and interventions.

Rationally-defined microbial consortia suppress multidrug-resistant proinflammatory Enterobacteriaceae via ecological control.

Persistent colonization and outgrowth of pathogenic organisms in the intestine may occur due to long-term antibiotic usage or inflammatory conditions, which perpetuate dysregulated immunity and tissue damage1,2. Gram-negative Enterobacteriaceae gut pathobionts are particularly recalcitrant to conventional antibiotic treatment3,4, though an emerging body of evidence suggests that manipulation of the commensal microbiota may be a practical alternative therapeutic strategy5-7. In this study, we rationally isolated and down-selected commensal bacterial consortia from healthy human stool samples capable of strongly and specifically suppressing intestinal Enterobacteriaceae. One of the elaborated consortia, consisting of 18 commensal strains, effectively controlled ecological niches by regulating gluconate availability, thereby reestablishing colonization resistance and alleviating antibiotic-resistant Klebsiella-driven intestinal inflammation in mice. Harnessing these microbial activities in the form of live bacterial therapeutics may represent a promising solution to combat the growing threat of proinflammatory, antimicrobial-resistant bacterial infection.

A dynamic partitioning mechanism polarizes membrane protein distribution.

The plasma membrane is widely regarded as the hub of the numerous signal transduction activities. Yet, the fundamental biophysical mechanisms that spatiotemporally compartmentalize different classes of membrane proteins remain unclear. Using multimodal live-cell imaging, here we first show that several lipid-anchored membrane proteins are consistently depleted from the membrane regions where the Ras/PI3K/Akt/F-actin network is activated. The dynamic polarization of these proteins does not depend upon the F-actin-based cytoskeletal structures, recurring shuttling between membrane and cytosol, or directed vesicular trafficking. Photoconversion microscopy and single-molecule measurements demonstrate that these lipid-anchored molecules have substantially dissimilar diffusion profiles in different regions of the membrane which enable their selective segregation. When these diffusion coefficients are incorporated into an excitable network-based stochastic reaction-diffusion model, simulations reveal that the altered affinity mediated selective partitioning is sufficient to drive familiar propagating wave patterns. Furthermore, normally uniform integral and lipid-anchored membrane proteins partition successfully when membrane domain-specific peptides are optogenetically recruited to them. We propose "dynamic partitioning" as a new mechanism that can account for large-scale compartmentalization of a wide array of lipid-anchored and integral membrane proteins during various physiological processes where membrane polarizes.

Sphingomyelin metabolism underlies Ras excitability for efficient cell migration and chemotaxis.

In eukaryotic motile cells, the active Ras (Ras-GTP)-enriched domain is generated in an asymmetric manner on the cell membrane through the excitable dynamics of an intracellular signaling network. This asymmetric Ras signaling regulates pseudopod formation for both spontaneous random migration and chemoattractant-induced directional migration. While membrane lipids, such as sphingomyelin and phosphatidylserine, contribute to Ras signaling in various cell types, whether they are involved in the Ras excitability for cell motility is unknown. Here we report that functional Ras excitability requires the normal metabolism of sphingomyelin for efficient cell motility and chemotaxis. The pharmacological blockade of sphingomyelin metabolism by an acid-sphingomyelinase inhibitor, fendiline, and other inhibitors suppressed the excitable generation of the stable Ras-GTP-enriched domain. The suppressed excitability failed to invoke enough basal motility to achieve directed migration under shallow chemoattractant gradients. The fendiline-induced defects in Ras excitability, motility and stimulation-elicited directionality were due to an accumulation of sphingomyelin on the membrane, which could be recovered by exogenous sphingomyelinase or phosphatidylserine without changing the expression of Ras. These results indicate a novel regulatory mechanism of the excitable system by membrane lipids, in which sphingomyelin metabolism provides a membrane environment to ensure Ras excitation for efficient cellular motility and chemotaxis.Key words: cell polarity, cell migration, Ras, excitability, sphingomyelin.

The specific core fucose-binding lectin Pholiota squarrosa lectin (PhoSL) inhibits hepatitis B virus infection in vitro.

Glycosylation of proteins and lipids in viruses and their host cells is important for viral infection and is a target for antiviral therapy. Hepatitis B virus (HBV) is a major pathogen that causes acute and chronic hepatitis; it cannot be cured because of the persistence of its covalently closed circular DNA (cccDNA) in hepatocytes. Here we found that Pholiota squarrosa lectin (PhoSL), a lectin that specifically binds core fucose, bound to HBV particles and inhibited HBV infection of a modified human HepG2 cell line, HepG2-hNTCP-C4, that expresses an HBV receptor, sodium taurocholate cotransporting polypeptide. Knockout of fucosyltransferase 8, the enzyme responsible for core fucosylation and that aids receptor endocytosis, in HepG2-hNTCP-C4 cells reduced HBV infectivity, and PhoSL facilitated that reduction. PhoSL also blocked the activity of epidermal growth factor receptor, which usually enhances HBV infection. HBV particles bound to fluorescently labeled PhoSL internalized into HepG2-hNTCP-C4 cells, suggesting that PhoSL might inhibit HBV infection after internalization. As PhoSL reduced the formation of HBV cccDNA, a marker of chronic HBV infection, we suggest that PhoSL could impair processes from internalization to cccDNA formation. Our finding could lead to the development of new anti-HBV agents.

Field model for multistate lateral diffusion of various transmembrane proteins observed in living Dictyostelium cells.

The lateral diffusion of transmembrane proteins on plasma membranes is a fundamental process for various cellular functions. Diffusion properties specific for individual protein species have been extensively studied, but the common features among protein species are poorly understood. Here, we systematically studied the lateral diffusion of various transmembrane proteins in the lower eukaryote Dictyostelium discoideum cells using a hidden Markov model for single-molecule trajectories obtained experimentally. As common features, all membrane proteins that had from one to ten transmembrane regions adopted three free diffusion states with similar diffusion coefficients regardless of their structural variability. All protein species reduced their mobility similarly upon the inhibition of microtubule or actin cytoskeleton dynamics, or myosin II. The relationship between protein size and the diffusion coefficient was consistent with the Saffman-Delbrück model, meaning that membrane viscosity is a major determinant of lateral diffusion, but protein size is not. These protein species-independent properties of multistate free diffusion were explained simply and quantitatively by free diffusion on the three membrane regions with different viscosities, which is in sharp contrast to the complex diffusion behavior of transmembrane proteins in higher eukaryotes.

A dynamic partitioning mechanism polarizes membrane protein distribution.

The plasma membrane is widely regarded as the hub of the signal transduction network activities that drives numerous physiological responses, including cell polarity and migration. Yet, the symmetry breaking process in the membrane, that leads to dynamic compartmentalization of different proteins, remains poorly understood. Using multimodal live-cell imaging, here we first show that multiple endogenous and synthetic lipid-anchored proteins, despite maintaining stable tight association with the inner leaflet of the plasma membrane, were unexpectedly depleted from the membrane domains where the signaling network was spontaneously activated such as in the new protrusions as well as within the propagating ventral waves. Although their asymmetric patterns resembled those of standard peripheral "back" proteins such as PTEN, unlike the latter, these lipidated proteins did not dissociate from the membrane upon global receptor activation. Our experiments not only discounted the possibility of recurrent reversible translocation from membrane to cytosol as it occurs for weakly bound peripheral membrane proteins, but also ruled out the necessity of directed vesicular trafficking and cytoskeletal supramolecular structure-based restrictions in driving these dynamic symmetry breaking events. Selective photoconversion-based protein tracking assays suggested that these asymmetric patterns instead originate from the inherent ability of these membrane proteins to "dynamically partition" into distinct domains within the plane of the membrane. Consistently, single-molecule measurements showed that these lipid-anchored molecules have substantially dissimilar diffusion profiles in different regions of the membrane. When these profiles were incorporated into an excitable network-based stochastic reaction-diffusion model of the system, simulations revealed that our proposed "dynamic partitioning" mechanism is sufficient to give rise to familiar asymmetric propagating wave patterns. Moreover, we demonstrated that normally uniform integral and lipid-anchored membrane proteins in Dictyostelium and mammalian neutrophil cells can be induced to partition spatiotemporally to form polarized patterns, by optogenetically recruiting membrane domain-specific peptides to these proteins. Together, our results indicate "dynamic partitioning" as a new mechanism of plasma membrane organization, that can account for large-scale compartmentalization of a wide array of lipid-anchored and integral membrane proteins in different physiological processes.

[Survey in Hyogo Prefecture on the Current Status of Pharmacists in Home Health Care and Exploration of Factors Causing Psychological Burden].

There is a need for pharmacists to be actively involved in home healthcare through a wide range of collaboration in healthcare and welfare. However, insufficient evidence is available to search for factors that prevent pharmacists from being proactive in home healthcare. In this study, we conducted an extensive questionnaire survey among pharmacists engaged in home pharmacy work who belong to the Hyogo Pharmaceutical Society regarding the current status of pharmacists' work in home medical care and their psychological burden; we also explored the factors that may hinder the future development of home medical care. As a result, 925 (44%) valid responses were obtained, and seven factors- "current multidisciplinary cooperation", "relationships with patients and their families", "emotional burden for home healthcare", "attitude toward patients", "ideal of multidisciplinary cooperation", "anxiety about aggressive intervention", and "anxiety about talking to and dealing with patients"- were extracted. Furthermore, it was suggested that pharmacists' mental burden and anxiety are closely related to their successful experiences in building relationships with patients and patients' families as well as with multidisciplinary cooperation in home healthcare. Therefore, to train pharmacists to be actively involved in home healthcare, it is important not only to impart knowledge and skills but also for them to gain experience practicing their contributions as pharmacists in the field of home healthcare with multiple professions, patients, and patients' families.

Effect of prior knowledge and peer evaluation ratings on final exam performance in a team-based learning chemistry course.

INTRODUCTION: Various reports have been published regarding adoption of team-based learning (TBL) in pharmacy education. However, there is insufficient published evidence on the effect of student characteristics on student learning outcomes in a TBL curriculum. The purpose of this research was to evaluate the effects of pre-study examination results and peer evaluation ratings on learning outcomes. METHODS: The TBL strategy was adopted for a basic chemistry exercise for first-year students at a private pharmacy school in Japan (2012-2019). For the analysis, students were divided into four analytical groups according to quartiles of pre-study examination results. The students were further divided into the high-peer evaluation rating group and low-peer evaluation rating group. We compared the final exam performance results between these groups. RESULTS: In all four groups by quartiles of pre-study examination results, the course final exam performance was higher for the high-peer evaluation rating students than for the low-peer evaluation rating students. CONCLUSIONS: Within the TBL framework, students with higher peer evaluation scores performed better on the final exam, regardless of the pre-study examination results.

Calcium responses to external mechanical stimuli in the multicellular stage of Dictyostelium discoideum.

Calcium acts as a second messenger to regulate many cellular functions, including cell motility. In Dictyostelium discoideum, the cytosolic calcium level oscillates synchronously, and calcium waves propagate through the cell population during the early stages of development, including aggregation. In the unicellular phase, the calcium response through Piezo channels also functions in mechanosensing. However, calcium dynamics during multicellular morphogenesis are still unclear. Here, live imaging of cytosolic calcium revealed that calcium wave propagation, depending on cAMP relay, disappeared at the onset of multicellular body (slug) formation. Later, other forms of occasional calcium bursts and their propagation were observed in both anterior and posterior regions of migrating slugs. This calcium signaling also occurred in response to mechanical stimuli. Two pathways-calcium release from the endoplasmic reticulum via IP3 receptor and calcium influx from outside the cell-were involved in calcium signals induced by mechanical stimuli. These data suggest that calcium signaling is involved in mechanosensing in both the unicellular and multicellular phases of Dictyostelium development using different molecular mechanisms.

Development of Low Molecular Weight Ligands for Integrin αvß3.

We designed and synthesized non-peptide organic molecular ligands for integrin αvß3. Candidate ligands featured amidino analog and carboxy groups as binding sites on either side of a spacer, which consisted of benzophenone or an analog, such as diphenyl sulfide, diphenyl sulfoxide, diphenyl sulfone, or diphenyl ether. Competitive binding assays to integrin αvß3 with respect to [125I]echistatin were used to determine inhibitory activity of the synthetic ligands. Ligands bearing 2-aminobenzimidazoyl and glycyl groups separated by a benzophenone spacer demonstrated more potent binding than did a linear Arg-Gly-Asp (RGD) tripeptide that represents the native integrin αvß3 binding motif. Ligands possessing 2-aminobenzimidazoyl and carboxy groups and diphenyl sulfoxide or diphenyl ether spacers inhibited binding of [125I]echistatin with IC50 values similar to that of the linear RGD tripeptide.

SRC kinase activator CDCP1 promotes hepatocyte growth factor-induced cell migration/invasion of a subset of breast cancer cells.

Cancer invasion and metastasis are the major causes of cancer patient mortality. Various growth factors, including hepatocyte growth factor (HGF), are known to promote cancer invasion and metastasis, but the regulatory mechanisms involved are not fully understood. Here, we show that HGF-promoted migration and invasion of breast cancer cells are regulated by CUB domain-containing protein 1 (CDCP1), a transmembrane activator of SRC kinase. In metastatic human breast cancer cell line MDA-MB-231, which highly expresses the HGF receptor MET and CDCP1, we show that CDCP1 knockdown attenuated HGF-induced MET activation, followed by suppression of lamellipodia formation and cell migration/invasion. In contrast, in the low invasive/nonmetastatic breast cancer cell line T47D, which had no detectable MET and CDCP1 expression, ectopic MET expression stimulated the HGF-dependent activation of invasive activity, and concomitant CDCP1 expression activated SRC and further promoted invasive activity. In these cells, CDCP1 expression dramatically activated HGF-induced membrane remodeling, which was accompanied by activation of the small GTPase Rac1. Analysis of guanine nucleotide exchange factors revealed that ARHGEF7 was specifically required for CDCP1-dependent induction of HGF-induced invasive ability. Furthermore, immunofluorescence staining demonstrated that CDCP1 coaccumulated with ARHGEF7. Finally, we confirmed that the CDCP1-SRC axis was also crucial for HGF and ARHGEF7-RAC1 signaling in MDA-MB-231 cells. Altogether, these results demonstrate that the CDCP1-SRC-ARHGEF7-RAC1 pathway plays an important role in the HGF-induced invasion of a subset of breast cancer cells.

Heterotrimeric Gq proteins act as a switch for GRK5/6 selectivity underlying ß-arrestin transducer bias.

Signaling-biased ligands acting on G-protein-coupled receptors (GPCRs) differentially activate heterotrimeric G proteins and ß-arrestins. Although a wealth of structural knowledge about signaling bias at the GPCR level exists (preferential engagement of a specific transducer), little is known about the bias at the transducer level (different functions mediated by a single transducer), partly due to a poor understanding of GPCR kinase (GRK)-mediated GPCR phosphorylation. Here, we reveal a unique role of the Gq heterotrimer as a determinant for GRK-subtype selectivity that regulates subsequent ß-arrestin conformation and function. Using the angiotensin II (Ang II) type-1 receptor (AT1R), we show that ß-arrestin recruitment depends on both GRK2/3 and GRK5/6 upon binding of Ang II, but solely on GRK5/6 upon binding of the ß-arrestin-biased ligand TRV027. With pharmacological inhibition or genetic loss of Gq, GRK-subtype selectivity and ß-arrestin functionality by Ang II is shifted to those of TRV027. Single-molecule imaging identifies relocation of AT1R and GRK5, but not GRK2, to an immobile phase under the Gq-inactive, AT1R-stimulated conditions. These findings uncover a previously unappreciated Gq-regulated mechanism that encodes GRK-subtype selectivity and imparts distinct phosphorylation-barcodes directing downstream ß-arrestin functions.

Structures and functions of the gut microbial lipidome.

Microbial lipids provide signals that are responsible for maintaining host health and controlling disease. The differences in the structures of microbial lipids have been shown to alter receptor selectivity and agonist/antagonist activity. Advanced lipidomics is an emerging field that helps to elucidate the complex bacterial lipid diversity. The use of cutting-edge technologies is expected to lead to the discovery of new functional metabolites involved in host homeostasis. This review aims to describe recent updates on functional lipid metabolites derived from gut microbiota, their structure-activity relationships, and advanced lipidomics technologies.

Four- and two-armed hetero porphyrin dimers: their specific recognition and self-sorting behaviours.

In this study we self-assembled the four-armed porphyrin hetero dimer capsule Cap4, stabilized through amidinium-carboxylate salt bridges, in CH2Cl2 and CHCl3. The dimer capsule Cap4 was kinetically and thermodynamically more stable than the corresponding two-armed dimer Cap2. The number of arms strongly influenced their recognition behaviour; guests possessing small aromatic faces (e.g., 1,3,5-trinitrobenzene) preferred residing in the cavity of the two-armed capsule Cap2, rather than in Cap4, both thermodynamically and kinetically; in contrast, large aromatic guests (e.g., 9,10-dibromoanthracene) were encapsulated predominantly by Cap4 because of favourable entropic effects. The number of arms enabled self-sorting behaviour of the dimer formation; complexation studies using an equimolar mixture of the four porphyrin constituents of the two capsules revealed the quantitative formation of the corresponding dimers Cap2 and Cap4. Furthermore, we examined the specific molecular recognition of Cap2 and Cap4; NMR experiments of mixtures of Cap2 and Cap4 in the presence of favourable guests for Cap2 and Cap4 revealed that these guest molecules were encapsulated selectively by their preferred hosts.

Synthesis of a Mechanically Planar Chiral and Axially Chiral [2]Rotaxane.

In this study, we synthesized a [2]rotaxane that was both mechanically planar chiral and axially chiral, comprising a symmetrical bis-crown ether featuring a biphenyl moiety (as the macrocyclic component) and a symmetrical bis-ammonium salt (as the dumbbell-shaped component).