Structural biology and molecular pharmacology of voltage-gated ion channels.

Voltage-gated ion channels (VGICs), including those for Na+, Ca2+ and K+, selectively permeate ions across the cell membrane in response to changes in membrane potential, thus participating in physiological processes involving electrical signalling, such as neurotransmission, muscle contraction and hormone secretion. Aberrant function or dysregulation of VGICs is associated with a diversity of neurological, psychiatric, cardiovascular and muscular disorders, and approximately 10% of FDA-approved drugs directly target VGICs. Understanding the structure-function relationship of VGICs is crucial for our comprehension of their working mechanisms and role in diseases. In this Review, we discuss how advances in single-particle cryo-electron microscopy have afforded unprecedented structural insights into VGICs, especially on their interactions with clinical and investigational drugs. We present a comprehensive overview of the recent advances in the structural biology of VGICs, with a focus on how prototypical drugs and toxins modulate VGIC activities. We explore how these structures elucidate the molecular basis for drug actions, reveal novel pharmacological sites, and provide critical clues to future drug discovery.

Dissection of the structure-function relationship of Nav channels.

Voltage-gated sodium channels (Nav) undergo conformational shifts in response to membrane potential changes, a mechanism known as the electromechanical coupling. To delineate the structure-function relationship of human Nav channels, we have performed systematic structural analysis using human Nav1.7 as a prototype. Guided by the structural differences between wild-type (WT) Nav1.7 and an eleven mutation-containing variant, designated Nav1.7-M11, we generated three additional intermediate mutants and solved their structures at overall resolutions of 2.9-3.4 Å. The mutant with nine-point mutations in the pore domain (PD), named Nav1.7-M9, has a reduced cavity volume and a sealed gate, with all voltage-sensing domains (VSDs) remaining up. Structural comparison of WT and Nav1.7-M9 pinpoints two residues that may be critical to the tightening of the PD. However, the variant containing these two mutations, Nav1.7-M2, or even in combination with two additional mutations in the VSDs, named Nav1.7-M4, failed to tighten the PD. Our structural analysis reveals a tendency of PD contraction correlated with the right shift of the static inactivation I-V curves. We predict that the channel in the resting state should have a "tight" PD with down VSDs.

NAD+ supplementation improves mitochondrial functions and normalizes glaucomatous trabecular meshwork features.

Glaucoma is characterized by pathological elevation of intraocular pressure (IOP) due to dysfunctional trabecular meshwork (TM), which is the primary cause of irreversible vision loss. There are currently no effective treatment strategies for glaucoma. Mitochondrial function plays a crucial role in regulating IOP within the TM. In this study, primary TM cells treated with dexamethasone were used to simulate glaucomatous changes, showing abnormal cellular cytoskeleton, increased expression of extracellular matrix, and disrupted mitochondrial fusion and fission dynamics. Furthermore, glaucomatous TM cell line GTM3 exhibited impaired mitochondrial membrane potential and phagocytic function, accompanied by decreased oxidative respiratory levels as compared to normal TM cells iHTM. Mechanistically, lower NAD + levels in GTM3, possibly associated with increased expression of key enzymes CD38 and PARP1 related to NAD + consumption, were observed. Supplementation of NAD + restored mitochondrial function and cellular viability in GTM3 cells. Therefore, we propose that the aberrant mitochondrial function in glaucomatous TM cells may be attributed to increased NAD + consumption dependent on CD38 and PARP1, and NAD + supplementation could effectively ameliorate mitochondrial function and improve TM function, providing a novel alternative approach for glaucoma treatment.

Targeting mechanics-induced trabecular meshwork dysfunction through YAP-TGFß Ameliorates high myopia-induced ocular hypertension.

High myopia is a risk factor for primary open angle glaucoma (POAG). The pathological mechanism of high myopia induced POAG occurrence is not fully understood. In this study, we successfully established the guinea pig model of ocular hypertension with high myopia, and demonstrated the susceptibility of high myopia for the occurrence of microbead-induced glaucoma compared with non-myopia group and the effect of YAP/TGF-ß signaling pathway in TM pathogenesis induced by high myopia. Moreover, we performed stretching treatment on primary trabecular meshwork (TM) cells to simulate the mechanical environment of high myopia. It was found that stretching treatment disrupted the cytoskeleton, decreased phagocytic function, enhanced ECM remodeling, and promoted cell apoptosis. The experiments of mechanics-induced human TM cell lines appeared the similar trend. Mechanically, the differential expressed genes of TM cells caused by stretch treatment enriched YAP/TGF-ß signaling pathway. To inhibit YAP/TGF-ß signaling pathway effectively reversed mechanics-induced TM damage. Together, this study enriches mechanistic insights of high myopia induced POAG susceptibility and provides a potential target for the prevention of POAG with high myopia.

Correlation between temporomandibular joints and craniocervical posture in patients with bilateral anterial disc displacement.

OBJECTIVE: To study the changes of temporomandibular joints and craniocervical posture in adult patients with bilateral anterior disc displacement, and to explore their correlation, which may provide some clinical value for clinical diagnosis and treatment planning. METHODS: Ninety-eight adult patients were divided into 3 groups: 29 patients in bilateral disc normal position group (BN), 33 patients in bilateral Anterior Disc Displacement With Reduction group (ADDWR) and 36 patients in bilateral Anterior Disc Displacement Without Reduction group (ADDWoR). Dolphin and Uceph software were used to measure 14 items of temporomandibular joint and 11 items of craniocervical posture for comparison and correlation analysis between groups. RESULTS: There were significant differences in bilateral joint space between three groups. Compared with the BN, the anteroposterior diameter of the condyle was significantly reduced, the condyle was significantly displaced posteriorly and superiorly in the ADDWR and ADDWoR, but the joint fossa width and joint fossa depth did not change significantly. Cervical curvature and inclination were greater in patients with anterior disc displacement than BN, indicating that the craniocervical posture of adult patients with anterior disc displacement was extended and protrusive. CONCLUSION: Anterior disc displacement of the temporomandibular joint can displace the condyle upwards and posteriorly and reduce the anteroposterior diameter of condyle, and then make the condyle closer to the wall of articular fossa to induce joint symptoms. Additionally, craniocervical postural position is significantly affected, which may be related to compensate for the effects of airway space.

Meta-analysis of combined azithromycin and inhaled budesonide treatment for Chinese pediatric patients with mycoplasma pneumonia.

BACKGROUND: Budesonide, capable of reducing vascular permeability, suppressing mucus secretion, and alleviating edema and spasms, is widely used in China for combined infectious disease treatment. This study assesses budesonide's efficacy and safety as an adjunct to azithromycin in pediatric Mycoplasma pneumonia management in China, aiming to establish a strong theoretical foundation for its clinical application. METHODS: We conducted a comprehensive search for qualifying studies across 5 English databases and 4 Chinese databases, covering publications until October 31, 2023. Endpoint analyses were performed using standard software (Stata Corporation, College Station, TX). This study was conducted in compliance with the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. RESULTS: A total of 24 randomized controlled trials were involved in the current study, including 2034 patients. Our findings indicate that the combination of budesonide with azithromycin for the treatment of pediatric Mycoplasma pneumonia delivers superior therapeutic efficacy (Intravenous: odds ratio [OR], 0.156, P < .001; Sequential: OR, 0.163, P = .001; Oral: OR, 0.139, P < .001), improved pulmonary function (Forced expiratory volume in 1 second: weighted mean differences [WMD], -0.28, P = .001; Peak expiratory flow: WMD, -0.554, P = .002; Forced vital capacity: WMD, -0.321, P < .001), diminished lung inflammation (IL-6: WMD, 4.760, P = .002; c-reactive protein: WMD, 5.520, P < .001; TNF-α: WMD, 9.124, P < .001), reduced duration of fever, faster resolution of cough and rales, all without increasing the occurrence of adverse events. CONCLUSION: The combination of budesonide and azithromycin demonstrates enhanced therapeutic effectiveness, promotes improved pulmonary function, shortens the duration of symptoms, and effectively mitigates the overexpression of inflammatory factors like c-reactive protein, TNF-α, and IL-6, all without an associated increase in adverse reactions in pediatric mycoplasma pneumonia.

Correlation between craniocervical posture and upper airway dimension in patients with bilateral anterior disc displacement.

OBJECTIVE: To investigate the relationship between upper airway dimension and craniocervical posture in adult patients with bilateral anterior disc displacement and to provide some references for clinical diagnosis and plan formulation in orthodontics. METHODS: Based on RDC/TMD (Research Diagnostic Criteria for Temporomandibular Disorder), 98 Patients were divided into three groups by two experienced TMJ (Temporomandibular Joint) specialists: bilateral disc normal position group (BN), bilateral anterior disc displacement with reduction group (ADDWR) and bilateral anterior disc displacement without reduction group (ADDWoR). Inter-group comparison and correlation analysis were performed after 11 craniocervical posture and 15 upper airway dimension measurements finished with Dolphin and Uceph software in Two or Three-dimensional. RESULTS: Anterior disc displacement often accompanied with extension of craniocervical posture, as ADDWR and ADDWoR groups have significantly higher cervical curvature and inclination than BN group (P < 0.05). Simultaneously anterior disc displacement often associated with constrained upper airway dimension for the total and each segment upper airway volume were significantly smaller in ADDWR and ADDWoR than BN group (P < 0.05). Correlation analysis revealed that C0-C1 (the distance from the base of the occipital bone (C0) to the posterior arch of the atlas (C1)) is significantly related to the total and each segment upper airway volume reduction (P < 0.05). CONCLUSION: There exists markedly close correlation between anterior disc displacement and craniocervical posture forward extension, which may be physiologically adaptive cervical extension to keep oropharyngeal airway unobstructed as upper airway dimension constrained by anterior disc displacement. CLINICAL RELEVANCE: These findings allow us to infer the potential consequences if the treatment of anterior disc displacement would result in an improvement of intervertebral relationships and upper airway constraint.

Structural basis for urate recognition and apigenin inhibition of human GLUT9.

Urate, the physiological form of uric acid and a potent antioxidant in serum, plays a pivotal role in scavenging reactive oxygen species. Yet excessive accumulation of urate, known as hyperuricemia, is the primary risk factor for the development of gout. The high-capacity urate transporter GLUT9 represents a promising target for gout treatment. Here, we present cryo-electron microscopy structures of human GLUT9 in complex with urate or its inhibitor apigenin at overall resolutions of 3.5 Å and 3.3 Å, respectively. In both structures, GLUT9 exhibits an inward open conformation, wherein the substrate binding pocket faces the intracellular side. These structures unveil the molecular basis for GLUT9's substrate preference of urate over glucose, and show that apigenin acts as a competitive inhibitor by occupying the substrate binding site. Our findings provide critical information for the development of specific inhibitors targeting GLUT9 as potential therapeutics for gout and hyperuricemia.

VEGF-C and 5-Fluorouracil Improve Bleb Survival in a Rabbit Glaucoma Surgery Trabeculectomy Model.

Purpose: To evaluate VEGF-C-induced lymphoproliferation in conjunction with 5-fluorouracil (5-FU) antimetabolite treatment in a rabbit glaucoma filtration surgery (GFS) model. Methods: Thirty-two rabbits underwent GFS and were assigned to four groups (n = 8 each) defined by subconjunctival drug treatment: (a) VEGF-C combined with 5-FU, (b) 5-FU, (c) VEGF-C, (d) and control. Bleb survival, bleb measurements, and IOP were evaluated over 30 days. At the end, histology and anterior segment OCT were performed on some eyes. mRNA was isolated from the remaining eyes for RT-PCR evaluation of vessel-specific markers (lymphatics, podoplanin and LYVE-1; and blood vessels, CD31). Results: Qualitatively and quantitatively, VEGF-C combined with 5-FU resulted in blebs which were posteriorly longer and wider than the other conditions: vs. 5-FU (P = 0.043 for longer, P = 0.046 for wider), vs. VEGF-C (P < 0.001, P < 0.001) and vs. control (P < 0.001, P < 0.001). After 30 days, the VEGF-C combined with 5-FU condition resulted in longer bleb survival compared with 5-FU (P = 0.025), VEGF-C (P < 0.001), and control (P < 0.001). Only the VEGF-C combined with 5-FU condition showed a negative correlation between IOP and time that was statistically significant (r = -0.533; P = 0.034). Anterior segment OCT and histology demonstrated larger blebs for the VEGF-C combined with 5-FU condition. Only conditions including VEGF-C led to increased expression of lymphatic markers (LYVE-1, P < 0.001-0.008 and podoplanin, P = 0.002-0.011). Expression of CD31 was not different between the groups (P = 0.978). Conclusions: Adding VEGF-C lymphoproliferation to standard antimetabolite treatment improved rabbit GFS success and may suggest a future strategy to improve human GFSs.