The long ß2,3-sheets encoded by redundant sequences play an integral role in the channel function of P2X7 receptors.

P2X receptors are a class of nonselective cation channels widely distributed in the immune and nervous systems, and their dysfunction is a significant cause of tumors, inflammation, leukemia, and immune diseases. P2X7 is a unique member of the P2X receptor family with many properties that differ from other subtypes in terms of primary sequence, the architecture of N- and C-terminals, and channel function. Here, we suggest that the observed lengthened ß2- and ß3-sheets and their linker (loop ß2,3), encoded by redundant sequences, play an indispensable role in the activation of the P2X7 receptor. We show that deletion of this longer structural element leads to the loss of P2X7 function. Furthermore, by combining mutagenesis, chimera construction, surface expression, and protein stability analysis, we found that the deletion of the longer ß2,3-loop affects P2X7 surface expression but, more importantly, that this loop affects channel gating of P2X7. We propose that the longer ß2,3-sheets may have a negative regulatory effect on a loop on the head domain and on the structural element formed by E171 and its surrounding regions. Understanding the role of the unique structure of the P2X7 receptor in the gating process will aid in the development of selective drugs targeting this subtype.

GSK1702934A and M085 directly activate TRPC6 via a mechanism of stimulating the extracellular cavity formed by the pore helix and transmembrane helix S6.

Transient receptor potential canonical (TRPC) channels, as important membrane proteins regulating intracellular calcium (Ca2+i) signaling, are involved in a variety of physiological and pathological processes. Activation and regulation of TRPC are more dependent on membrane or intracellular signals. However, how extracellular signals regulate TRPC6 function remains to be further investigated. Here, we suggest that two distinct small molecules, M085 and GSK1702934A, directly activate TRPC6, both through a mechanism of stimulation of extracellular sites formed by the pore helix (PH) and transmembrane (TM) helix S6. In silico docking scanning of TRPC6 identified three extracellular sites that can bind small molecules, of which only mutations on residues of PH and S6 helix significantly reduced the apparent affinity of M085 and GSK1702934A and attenuated the maximal response of TRPC6 to these two chemicals by altering channel gating of TRPC6. Combing metadynamics, molecular dynamics simulations, and mutagenesis, we revealed that W679, E671, E672, and K675 in the PH and N701 and Y704 in the S6 helix constitute an orthosteric site for the recognition of these two agonists. The importance of this site was further confirmed by covalent modification of amino acid residing at the interface of the PH and S6 helix. Given that three structurally distinct agonists M085, GSK1702934A, and AM-0883, act at this site, as well as the occupancy of lipid molecules at this position found in other TRP subfamilies, it is suggested that the cavity formed by the PH and S6 has an important role in the regulation of TRP channel function by extracellular signals.

The Signaling Pathways and Targets of Natural Compounds from Traditional Chinese Medicine in Treating Ischemic Stroke.

Ischemic stroke (IS) is a common neurological disorder associated with high disability rates and mortality rates. At present, recombinant tissue plasminogen activator (r-tPA) is the only US(FDA)-approved drug for IS. However, due to the narrow therapeutic window and risk of intracerebral hemorrhage, r-tPA is currently used in less than 5% of stroke patients. Natural compounds have been widely used in the treatment of IS in China and have a wide range of therapeutic effects on IS by regulating multiple targets and signaling pathways. The keywords "ischemia stroke, traditional Chinese Medicine, Chinese herbal medicine, natural compounds" were used to search the relevant literature in PubMed and other databases over the past five years. The results showed that JAK/STAT, NF-κB, MAPK, Notch, Nrf2, and PI3K/Akt are the key pathways, and SIRT1, MMP9, TLR4, HIF-α are the key targets for the natural compounds from traditional Chinese medicine in treating IS. This study aims to update and summarize the signaling pathways and targets of natural compounds in the treatment of IS, and provide a base of information for the future development of effective treatments for IS.

Interaction between smoking and CYP2C19*3 polymorphism increased risk of lung cancer in a Chinese population.

Cytochrome P450 (CYP) 2C19 is expressed in vascular endothelium and metabolizes arachidonic acid to biologically active epoxyeicosatrienoic acids (EETs), which play a crucial role in either the detoxification or inactivation of potential carcinogens, or the bioactivation of some environmental procarcinogens to reactive DNA-binding metabolites. And smoking is a major risk factor for lung cancer. The purpose of this study is to explore the relationship between the interaction of CYP2C19*3 polymorphism and smoking and lung cancer in a Chinese population. In a Chinese case-control study of lung cancer patients (n=420) and healthy controls (n=420), we investigated the roles of CYP2C19*3 polymorphism in lung cancer risk using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. We found that the frequency of CYP2C19 (*)3 (AG + AA) genotype was significantly higher in lung cancer patients than that in control subjects (14.28 % versus 4.76 %; P<0.001). Multivariable logistic regression analysis showed that after adjustment of other risk factors, the A allele of CYP2C19*3 remains significantly associated with lung cancer. We also found that there was a significant interaction between CYP2C19 (*)3 and smoking in increasing the risk for lung cancer (OR 5.121, 95 % confidence interval [CI] 4.321-10.124; P=0.001). The interaction between CYP2C19 (*)3 polymorphism and smoking plays an important role in the mechanism of lung cancer in Chinese population.

Comparison of Computed Tomography and Clinical Features Between Patients Infected with the SARS-CoV-2 Omicron Variant and the Original Strain.

Purpose: To investigate potential differences in clinical and computed tomography (CT) features between patients with the SARS-CoV-2 Omicron variant and the original strain. Patients and Methods: This retrospective study included 69 hospitalized patients infected with Omicron variant from November to December 2022, and 96 hospitalized patients infected with the original strain from February to March 2020 in Chongqing, China. The clinical features, CT manifestations, degrees of lung involvement in different stages on CT, and imaging changes after the reverse-transcription polymerase chain reaction (RT-PCR) results turned negative were compared between the two groups. Results: For clinical features, patients with Omicron were predominantly old people and females, without manifestation of any clinical symptoms, who had low serum levels of C-reactive protein and procalcitonin. Shorter interval from symptoms onset to initial CT scan was observed in Omicron patients compared to patients with the original strain (all P < 0.05). For CT features, patients with Omicron were more likely to present with round-like opacities and tree-in-bud pattern (all P < 0.05), but less likely to exhibit a diffuse distribution, patchy and linear opacities, as well as vascular enlargement pattern (all P < 0.05). The Omicron group was more susceptible to exhibiting lower CT involvement scores in each stage (all P < 0.05) and imaging progression after the RT-PCR results turned negative (P < 0.001). Conclusion: Patients infected with the Omicron variant exhibited less severe changes on chest CT compared to those infected with the original strain. Furthermore, imaging progression under low viral load conditions was more common in patients with Omicron than in those with the original strain.

Clinical and non-contrast computed tomography characteristics and disease development in patients with benign pulmonary subsolid nodules with a solid component ≤ 5 mm.

OBJECTIVES: To evaluate the clinical and non-contrast computed tomography (CT) features of patients with benign pulmonary subsolid nodules (SSNs) with a solid component ≤ 5 mm and their development trends via follow-up CT. METHODS: We retrospectively collected 436 data from patients who had SSNs with a solid component ≤ 5 mm, including 69 with absorbable benign SSNs (AB-SSNs), 70 with nonabsorbable benign SSNs (NB-SSNs), and 297 with malignant SSNs (M-SSNs). Models 1, 2, and 3 for distinguishing the different types of SSNs were then developed and validated. RESULTS: Patients with AB-SSNs were younger and exhibited respiratory symptoms more frequently than those with M-SSNs. The frequency of nodules detected during follow-up CT was in the following order: AB-SSNs > NB-SSNs > M-SSNs. NB-SSNs were smaller than M-SSNs, and ill-defined margins were more frequent in AB-SSNs than in NB-SSNs and M-SSNs. Benign SSNs exhibited irregular shape, target sign, and lower CT values more frequently compared to M-SSNs, whereas the latter demonstrated bubble lucency more commonly compared to the former. Furthermore, AB-SSNs showed more thickened interlobular septa and satellite lesions than M-SSNs and M-SSNs had more pleural retraction than AB-SSNs (all p < 0.017). The three models had AUCs ranging 0.748-0.920 and 0.790-0.912 in the training and external validation cohorts, respectively. A follow-up CT showed nodule progression in four benign SSNs. CONCLUSIONS: The three SSN types have different clinical and imaging characteristics, with some benign SSNs progressing to resemble malignancy. CRITICAL RELEVANCE STATEMENT: A good understanding of the imaging features and development trends of benign SSNs may help reduce unnecessary follow-up or interventions. This retrospective study explores the CT characteristics of benign SSNs with a solid component ≤ 5 mm by comparing AB-SSNs, NB-SSNs, and M-SSNs and delineates their development trends via follow-up CT. KEY POINTS: 1. Different subsolid nodule types exhibit distinct clinical and imaging features. 2. A miniscule number of benign subsolid nodules can progress to resemble malignancy. 3. Knowing the clinical and imaging features and development trends of benign subsolid nodules can improve management.

Remote Health Management via WeChat to Improve the Quality of Life of Patients After PCI.

OBJECTIVES: The purpose of this research was to assess the effect of telehealth management via WeChat on improving the quality of life of patients after percutaneous coronary intervention (PCI). METHODS: In this study, we retrospectively collected the clinical data of 118 patients who underwent PCI and received remote health management from our hospital via WeChat from June 2021 to September 2021 (WeChat group). The clinical data of 114 patients who underwent PCI but did not receive remote health management from our hospital from September 2020 to December 2020 were also collected (conventional group). Anxiety, depression, and quality of life scale scores were compared between the 2 groups at 6 months postdischarge. RESULTS: Six months postdischarge, patients in the WeChat group had significantly lower Self-rating Anxiety Scale (SAS) (55.7 ± 7.2 vs 58.8 ± 6.4, P = .001) and Self-rating Depression Scale (SDS) (56.0 ± 5.9 vs 58.2 ± 6.2, P = .007) scores than did those in the conventional group. Compared to those in the conventional group, the patients in the WeChat group had significantly greater 6 months post-discharge The World Health Organization Quality of Life - BREF scores in the following domains: physical (14.3 ± 1.7 vs 13.1 ± 1.7, P < .001 psychological (15.2 ± 1.3 vs 13.5 ± 1.5, P < .001 social relationship (12.9 ± 1.7 vs 12.3 ± 1.8, P = .01) and environmental (12.7 ± 2.0 vs 12.0 ± 1.9, P = .006). CONCLUSION: The use of WeChat to carry out remote health management for patients who underwent PCI can be an effective way to provide high-quality hospital medical services to patients' families and can effectively alleviate patients' anxiety and depression and enhance their quality of life.

Flotillin-2 is associated with breast cancer progression and poor survival outcomes.

BACKGROUND: Flotillin-2 (FLOT2) has been implicated in several signaling pathways in tumor cells. Our study aimed to investigate the expression pattern and clinicopathological significance of FLOT2 in patients with breast cancer. METHODS: The expression level of FLOT2 in normal breast epithelial cells, breast cancer cell lines, and four breast cancer biopsies paired with adjacent noncancerous tissues were quantified using real-time RT-PCR and Western blotting. FLOT2 protein expression was analyzed in 171 archived paraffin-embedded breast cancer samples using immunohistochemistry (IHC). Statistical analyses were performed to evaluate the clinicopathological significance of FLOT2 expression. RESULTS: FLOT2 was significantly upregulated in breast cancer cell lines and tissue samples compared with normal cells and adjacent noncancerous breast tissues, respectively. IHC analysis revealed high expression levels of FLOT2 in 82 of 171 (48.0%) breast cancer specimens. Statistical analysis revealed that FLOT2 expression was significantly correlated with clinical stage (P < 0.001), T classification (P < 0.001), M classification (P < 0.001), histological differentiation (P = 0.005) and ErbB2 expression (P = 0.003). Patients with higher levels of FLOT2 expression had a shorter overall survival duration than patients with lower FLOT2 expression levels. Multivariate analysis suggested that FLOT2 expression was an independent prognostic marker for survival in patients with breast cancer. CONCLUSIONS: The current results demonstrated that high FLOT2 protein expression was associated with poor outcomes in patients with breast cancer. FLOT2 could be used as a prognostic biomarker for breast cancer progression.

Emerging roles of RNA binding proteins in intervertebral disc degeneration and osteoarthritis.

The etiology of intervertebral disc degeneration (IDD) and osteoarthritis (OA) is complex and multifactorial. Both predisposing genes and environmental factors are involved in the pathogenesis of IDD and OA. Moreover, epigenetic modifications affect the development of IDD and OA. Dysregulated phenotypes of nucleus pulposus (NP) cells and OA chondrocytes, including apoptosis, extracellular matrix disruption, inflammation, and angiogenesis, are involved at all developmental stages of IDD and OA. RNA binding proteins (RBPs) have recently been recognized as essential post-transcriptional regulators of gene expression. RBPs are implicated in many cellular processes, such as proliferation, differentiation, and apoptosis. Recently, several RBPs have been reported to be associated with the pathogenesis of IDD and OA. This review briefly summarizes the current knowledge on the RNA-regulatory networks controlled by RBPs and their potential roles in the pathogenesis of IDD and OA. These initial findings support the idea that specific modulation of RBPs represents a promising approach for managing IDD and OA.

Calcium carbonate-gold nanocluster hybrid spheres: synthesis and versatile application in immunoassays.

Fluorescent gold nanoclusters (AuNCs) were incorporated into porous calcium carbonate spheres through electrostatic interaction. The resulting CaCO(3)/AuNCs hybrid material exhibited interesting properties, such as porous structure, excellent biocompatibility, good water solubility, and degradability. These properties make the CaCO(3)/AuNCs hybrid material a promising template to assemble horseradish peroxidase/antibody conjugates (HRP-Ab(2)). By using CaCO(3)/AuNCs/HRP-Ab(2) bioconjugates as probes, a versatile immunosensor was developed for fluorescent and electrochemical detection of the cancer biomarker neuron-specific enolase (NSE). The detection limits of the sensor were 2.0 and 0.1 pg mL(-1) for fluorescent and electrochemical detection, respectively. The immunosensor shows high sensitivity and offers an alternative strategy for the detection of other proteins and DNA.

[Reconstruction of anterior talofibular ligament and calcaneofibular ligament with autologous peroneus brevis tendon in the treatment of chronic lateral ankle instability].

OBJECTIVE: To explore the clinical efficacy of reconstruction the anterior talofibular ligament and calcaneofibular ligament with autologous peroneus brevis tendon for the treatment of chronic lateral ankle instability. METHODS: The clinical data of 42 patients with chronic lateral ankle instability treated by anatomical reconstruction of anterior talofibular ligament and calcaneofibular ligament with autologous peroneus brevis tendon from July 2016 to July 2019 was retrospectively analyzed. Including 30 males and 12 females, age ranged from 25 to 46 years old with an average of (37.6±12.4) years. There were 15 cases of left foot and 27 cases of right foot, the time from injury to operation was 3 to 12 months with a mean of (7.4±2.8) months. And 14 patients had tenderness in lateral collateral ligament area, 28 patients complained of multiple ankle sprains while walking on the flat ground. At 12 months after operation, the talar tilt angle and visual analogue scale(VAS)were observed, ankle joint varus stress and anterior drawer test were performed to check the mechanical stability of the ankle joint, American Orhopaedic Foot and Ankle Society(AOFAS) was used to score the ankle and hindfoot functions and evaluate the curative effect. RESULTS: Forty patients were followed up for 12 to 48 months with an average of (28.3±10.0) months, 2 cases were lost. The VAS decreased from(4.50±0.93) scores before surgery to (1.10±0.30) scores at 12 months after surgery;the talar tilt angle was reduced from (12.26±1.13)° before operation to (4.60±0.45)° at 12 months after operation;the AOFAS score increased from (65.10±7.50)scores before surgery to (84.40±3.95) scores at 12 months after surgery;all the differences were statically significant(P<0.05). According to the AOFAS score, 27 cases got excellent results, 7 good, 5 fair, and 1 poor. One patient had the symptoms of sural nerve injury after operation, and the symptoms were relieved after oral Mecobalamin for 3 months. The remaining patients had no complications such as nerve injury, infection, and skin necrosis. There was no instability of ankle joint, and both ankle varus stress test and drawer test were negative. CONCLUSION: Autologous peroneal brevis tendon with double bone channel pass through the tendon (modified Chrisman-Snook operation) can anatomically reconstruct the anterior talofibular ligament and the calcaneofibular ligament, restore the stability of the patient's ankle joint, reduce postoperative complications, and restore ankle joint function well.

Multi-Omics Approaches in Colorectal Cancer Screening and Diagnosis, Recent Updates and Future Perspectives.

Colorectal cancer (CRC) is common Cancer as well as the third leading cause of mortality around the world; its exact molecular mechanism remains elusive. Although CRC risk is significantly correlated with genetic factors, the pathophysiology of CRC is also influenced by external and internal exposures and their interactions with genetic factors. The field of CRC research has recently benefited from significant advances through Omics technologies for screening biomarkers, including genes, transcripts, proteins, metabolites, microbiome, and lipidome unbiasedly. A promising application of omics technologies could enable new biomarkers to be found for the screening and diagnosis of CRC. Single-omics technologies cannot fully understand the molecular mechanisms of CRC. Therefore, this review article aims to summarize the multi-omics studies of Colorectal cancer, including genomics, transcriptomics, proteomics, microbiomics, metabolomics, and lipidomics that may shed new light on the discovery of novel biomarkers. It can contribute to identifying and validating new CRC biomarkers and better understanding colorectal carcinogenesis. Discovering biomarkers through multi-omics technologies could be difficult but valuable for disease genotyping and phenotyping. That can provide a better knowledge of CRC prognosis, diagnosis, and treatments.

Dynamic recognition of naloxone, morphine and endomorphin1 in the same pocket of µ-opioid receptors.

Morphine, the most widely used analgesic, relieves severe pain by activating the µ-opioid receptor (MOR), whereas naloxone, with only slight structural changes compared to morphine, exhibits inhibitory effect, and is used to treat opioid abuse. The mechanism by which the MOR distinguishes between the two is unclear. Molecular dynamics (MD) simulations on a 1-µs time scale and metadynamics-enhanced conformational sampling are used here to determine the different interactions of these two ligands with MOR: morphine adjusted its pose by continuously flipping deeper into the pocket, whereas naloxone failed to penetrate deeper because its allyl group conflicts with several residues of MOR. The endogenous peptide ligand endomorphin-1 (EM-1) underwent almost no significant conformational changes during the MD simulations. To validate these processes, we employed GIRK4S143T, a MOR-activated Gßγ-protein effector, in combination with mutagenesis and electrophysiological recordings. We verified the role of some key residues in the dynamic recognition of naloxone and morphine and identified the key residue I322, which leads to differential recognition of morphine and naloxone while assisting EM-1 in activating MOR. Reducing the side chain size of I322 (MORI322A) transformed naloxone from an inhibitor directly into an agonist of MOR, and I322A also significantly attenuated the potency of MOR on EM-1, confirming that binding deep in the pocket is critical for the agonistic effect of MOR. This finding reveals a dynamic mechanism for the response of MOR to different ligands and provides a basis for the discovery of new ligands for MOR at the atomic level.

Thymopentin-Mediated Inhibition of Cancer Stem Cell Stemness Enhances the Cytotoxic Effect of Oxaliplatin on Colon Cancer Cells.

Thymopentin (TP5) is an immunomodulatory pentapeptide that has been widely used in malignancy patients with immunodeficiency due to radiotherapy and chemotherapy. Here, we propose that TP5 directly inhibits the stemness of colon cancer cells HCT116 and therefore enhances the cytotoxicity of oxaliplatin (OXA) in HCT116 cells. In the absence of serum, TP5 was able to induce cancer stemness reduction in cultured HCT116 cells and significantly reduced stemness-related signals, such as the expression of surface molecular markers (CD133, CD44 and CD24) and stemness-related genes (ALDH1, SOX2, Oct-4 and Nanog), and resulted in altered Wnt/ß-catenin signaling. Acetylcholine receptors (AchRs) are implicated in this process. OXA is a common chemotherapeutic agent with therapeutic effects in various cancers. Although TP5 had no direct effect on the proliferation of HCT116, this pentapeptide significantly increased the sensitivity of HCT116 to OXA, where the effect of TP5 on the stemness of colon cancer cells through stimulation of AchRs may contribute to this process. Our results provide a promising strategy for increasing the sensitivity of colon cancer cells to chemotherapeutic agents by incorporating immunomodulatory peptides.

Prediction of the mechanism of Dachengqi Decoction treating colorectal cancer based on the analysis method of " into serum components -action target-key pathway".

ETHNOPHARMACOLOGICAL RELEVANCE: Colorectal cancer (CRC) is a common digestive tract malignant tumor that its morbidity and mortality seriously affect human health. At present, Dachengqi Decoction (DCQ), a traditional Chinese medicine formula, has been clinically used as an adjuvant therapy for CRC. However, pharmacodynamic substance basis and therapeutic mechanism are still unclear. AIM OF THE STUDY: The main constituents absorbed in the blood and possible active targets after DCQ administration were explored based on the analysis method of "into serum components, action target and key pathway", which may provide reference for the study of the pharmacodynamic material basis and action mechanism of Dachengqi Decoction in the treatment of CRC. MATERIAL AND METHODS: Based on the serum pharmacochemistry of traditional Chinese medicine (TCM), the prescription prototype ingredients of DCQ in mice serum samples were identified by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry technology (UPLC-Q-TOF-MSE). Taking the prototype ingredients absorbed into serum as the research object, the possible targets and key pathways of DCQ in vivo were demonstrated by network pharmacology. Finally, using molecular docking verified the binding activity of prototype components and potential action targets. RESULTS: A total of 46 prototype components of DCQ were identified in mice serum, most of which were derived from flavonoids and anthraquinones in Citrus aurantium L. and Rheum palmatum L. Network pharmacology prediction results indicated that the drug prototype components entering the serum may mainly regulate targets including mitogen-activated protein kinase (MAPK), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), etc. and main pathways such as (phosphatidylinositol 3-kinase/protein kinase B) PI3K-AKT signaling pathway, advanced glycation end products-receptor for AGE (AGE-RAGE) signaling pathway and IL-17 signaling pathway, etc. Molecular docking showed that the prototype active components had strong binding activity to VEGF, Harvey rat sarcoma viral oncogene homolog (HRAS) and MAPK1. CONCLUSIONS: This study elucidated that most of the direct acting substances of DCQ in vivo were flavonoids and anthraquinones, which may play a role in regulating cell reproduction and apoptosis and inhibiting inflammation, providing a reference for the research of pharmacodynamic material basis and mechanism of DCQ in the treatment of CRC.

Vanilloid agonist-mediated activation of TRPV1 channels requires coordinated movement of the S1-S4 bundle rather than a quiescent state.

Transient receptor potential vanilloid1 (TRPV1) channel plays an important role in a wide range of physiological and pathological processes, and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention. Recent incredible advances in cryo-electron microscopy (cryo-EM) have yielded high-resolution structures of all TRPV subtypes (TRPV1-6) and all of them share highly conserved six transmembrane (TM) domains (S1-S6). As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist (capsaicin or resiniferatoxin), TM helicesS1 to S4 form a bundle that remains quiescent during channel activation, highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels. Here, however, we argue that the structural dynamics rather than quiescence of S1-S4 domains is necessary for capsaicin-mediated activation of TRPV1. Using fluorescent unnatural amino acid (flUAA) incorporation and voltage-clamp fluorometry (VCF) analysis, we directly observed allostery of the S1-S4 bundle upon capsaicin binding. Covalent occupation of VCF-identified sites, single-channel recording, cell apoptosis analysis, and exploration of the role of PSFL828, a novel non-vanilloid agonist we identified, have collectively confirmed the essential role of this coordinated S1-S4 motility in capsaicin-mediated activation of TRPV1. This study concludes that, in contrast to cryo-EM structural studies, vanilloid agonists are also required for S1-S4 movement during TRPV1 activation. Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.

P2X3-selective mechanism of Gefapixant, a drug candidate for the treatment of refractory chronic cough.

Gefapixant/AF-219, a selective inhibitor of the P2X3 receptor, is the first new drug other than dextromethorphan to be approved for the treatment of refractory chronic cough (RCC) in nearly 60 years. To date, seven P2X subtypes (P2X1-7) activated by extracellular ATP have been cloned, and subtype selectivity of P2X inhibitors is a prerequisite for reducing side effects. We previously identified the site and mechanism of action of Gefapixant/AF-219 on the P2X3 receptor, which occupies a pocket consisting of the left flipper (LF) and lower body (LB) domains. However, the mechanism by which AF-219 selectively acts on the P2X3 receptor is unknown. Here, we combined mutagenesis, chimera construction, molecular simulations, covalent occupation and chemical synthesis, and find that the negative allosteric site of AF-219 at P2X3 is also present in other P2X subtypes, at least for P2X1, P2X2 and P2X4. By constructing each chimera of AF-219 sensitive P2X3 and insensitive P2X2 subtypes, the insensitive P2X2 subtype was made to acquire the inhibitory properties of AF-219 and AF-353, an analog of AF-219 with higher affinity. Our results suggest that the selectivity of AF-219/AF-353 for P2X3 over the other P2X subtypes is determined by a combination of the accessibility of P2X3 binding site and the internal shape of this pocket, a finding that could provide new perspectives for drug design against P2X3-mediated diseases such as RCC, idiopathic pulmonary fibrosis, hypertension and overactive bladder disorder.

Expression of Trichoderma viride endoglucanase III in the larvae of silkworm, Bombyx mori L. and characteristic analysis of the recombinant protein.

Endoglucanase is a part of cellulase which hydrolyzes cellulose into glucose. In this study, we cloned endoglucanase III (EG III) gene from Trichoderma viride strain AS 3.3711 using a PCR-based exon splicing method, and expressed EG III recombinant protein in both silkworm BmN cell line and silkworm larvae with an improved Bac-to-Bac/BmNPV mutant baculovirus expression system, which lacks the chiA and v-cath genes of Bombyx mori nucleopolyhedrovirus (BmNPV). The result showed that around 45 kDa protein was visualized in BmN cells at 48 h after the second generation recombinant mBacmid/BmNPV/EG III baculovirus infection. The enzymes from recombinant baculoviruses infected silkworms exhibited significant maximum enzyme activity at the environmental condition of pH 8.0 and temperature 50°C, and increased 20.94 and 19.13% compared with that from blank mBacmid/BmNPV baculoviruses infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 9.0 and at temperature range from 40 to 60°C. It provided a possibility to generate transgenic silkworms expressing bio-active cellulase, which can catabolize dietary fibers more efficiently, and it might be of great significance for sericulture industry.

Cloning and characterization of the Bombyx mori ecdysone oxidase.

The physiological titer of molting hormones in insects depends on relative activities of synthesis and degradation pathways. Ecdysone oxidase (EO) is a key enzyme in the inactivation of ecdysteroid. However, there are only a few reports on ecdysteroid inactivation and its enzymes in silkworm. In this study, we cloned and characterized the Bombyx mori EO (BmEO). The BmEO cDNA contains an ORF of 1,695 bp and the deduced protein sequence contains 564 amino acid residues. The deduced protein sequence contains two functional domains of glucose-methanol-choline oxidoreductase in N-terminal and C-terminal. Comparing the expression levels of BmEO in different tissues, high transcription was mainly present in hemocytes. Reduced expression of this enzyme is expected to lead to pathological accumulation of ecdysone in the hemolymph of silkworm larvae or pupae. Our data show that RNA inference of BmEO transcripts resulted in the accumulation of ecdysteroid and death of larvae or pupae. We infer that EO is a crucial element in the physiology of insect development.

Cloning and expression pattern of 3-dehydroecdysone 3ß-reductase (3DE 3ß-reductase) from the silkworm, Bombyx mori L.

Molting in insects is regulated by molting hormones (ecdysteroids), which are also crucial to insect growth, development, reproduction, etc. Ecdysone was inactivated to 3-dehydroecdysone (3DE) under ecdysone oxidase (EO), and followed by NAD(P)H-dependent irreversible reduction to 3-epiecdysteroid under 3DE 3a-reductase. On the other hand, 3-dehydroecdysone undergoes reversible reduction to ecdysone by 3DE 3ß-reductase in the hemolymph. In this article, we cloned and characterized 3-dehydroecdysone 3ß-reductase (3DE 3ß-reductase) in the different tissues and the developing stage from the silkworm, Bombyx mori L. The B. mori 3DE 3ß-reductase cDNA contains an ORF 972 bp and the deduced protein sequence containing 323 amino acid residues. Analysis showed that the deduced 3DE 3ß-reductase belongs to the aldo-keto reductase (AKR) superfamily, which has the NAD(P)-binding domain, indicating that the function of 3DE 3ß-reductase depends on the existence of NAD(P)H. Using Escherichia coli, a high level expression of a fusion polypeptide band of approx. 40 kDa was observed. The high transcription of 3DE 3ß-reductase was mainly observed in the genitalia and fatty bodies in the third day of the fifth-instar larvae, followed next in the head, epidermis, and hemocytes. The expression of 3DE 3ß-reductase in the early of every instar was lower than that in the late of instar. When the titer of 3DE is low, higher expression of 3DE 3ß-reductase is necessary to maintain the ecdysone titer in body through converting 3DE to ecdysone, while the 3DE titer is high, the expression of 3DE 3ß-reductase showed feedback inhibition.