Intra-channel bi-epitopic crosslinking unleashes ultrapotent antibodies targeting NaV1.7 for pain alleviation.

Crucial for cell activities, ion channels are key drug discovery targets. Although small-molecule and peptide modulators dominate ion channel drug discovery, antibodies are emerging as an alternative modality. However, challenges persist in generating potent antibodies, especially for channels with limited extracellular epitopes. We herein present a bi-epitopic crosslinking strategy to overcome these challenges, focusing on NaV1.7, a potential analgesic target. Aiming to crosslink two non-overlapping epitopes on voltage-sensing domains II and IV, we construct bispecific antibodies and ligand-antibody conjugates. Enhanced affinity and potency are observed in comparison to the monospecific controls. Among them, a ligand-antibody conjugate (1080-PEG7-ACDTB) displays a two-orders-of-magnitude improvement in potency (IC50 of 0.06 ± 0.01 nM) and over 1,000-fold selectivity for NaV1.7. Additionally, this conjugate demonstrates robust analgesic effects in mouse pain models. Our study introduces an approach to developing effective antibodies against NaV1.7, thereby initiating a promising direction for the advancement of pain therapeutics.

Reconstitution of Arp2/3-nucleated actin assembly with proteins CP, V-1, and CARMIL.

Actin polymerization is often associated with membrane proteins containing capping-protein-interacting (CPI) motifs, such as capping protein, Arp2/3, myosin I linker (CARMIL), CD2AP, and WASHCAP/Fam21. CPI motifs bind directly to actin-capping protein (CP), and this interaction weakens the binding of CP to barbed ends of actin filaments, lessening the ability of CP to functionally cap those ends. The protein V-1/myotrophin binds to the F-actin-binding site on CP and sterically blocks CP from binding barbed ends. CPI-motif proteins also weaken the binding between V-1 and CP, which decreases the inhibitory effects of V-1, thereby freeing CP to cap barbed ends. Here, we address the question of whether CPI-motif proteins on a surface analogous to a membrane lead to net activation or inhibition of actin assembly nucleated by Arp2/3 complex. Using reconstitution with purified components, we discovered that CARMIL at the surface promotes and enhances actin assembly, countering the inhibitory effects of V-1 and thus activating CP. The reconstitution involves the presence of an Arp2/3 activator on the surface, along with Arp2/3 complex, V-1, CP, profilin, and actin monomers in solution, recreating key features of cell physiology.

Characterization and phylogenetic analysis of vomeronasal receptors in the female muskrat (Ondatra zibethicus).

Vomeronasal receptors (VRs) play a crucial role in recognizing pheromones, which are essential for social chemical communication. The male muskrat (Ondatra zibethicus) secretes musk, which contains pheromones as a reproductive signal, and the female can recognize it through the VNO to mediate social communication behavior. This study aimed to identify the genomic information of VRs (OzVRs) in the female muskrat and elucidate their physicochemical properties and evolutionary relationship. Six predominantly expressed OzVR genes were identified using the RACE technique, and a comprehensive analysis was conducted on their gene structure, subcellular distribution, functional predictions, and mRNA levels, revealed that all OzVRs were transmembrane proteins. Phylogenetic analysis clustered OzVR genes into two clades (V1Rs: OzV1R21, OzV1R81, OzV1R105; V2Rs: OzV2R33, OzV2R44, OzV2R60). Physiochemically, OzV1Rs were basic proteins, while OzV2Rs exhibited weakly acidic character. Among them, OzV1R81 and OzV2R44 were identified as hydrophobicitystable proteins, with the remainder categorized as hydrophobicity-unstable proteins. Promoters analysis revealed the involvement of transcription factors and complexes, including Ahr::Arnt, Runx1, Arnt, and TFAP2A, in regulating the expression of the OzVR genes. Conserved domain and motif analyses demonstrated a high conservation of the VRs superfamily in rodents, with many conserved domains linked to pheromone binding. Functional predictions confirmed that OzVRs were associated with pheromones detection. Finally, the expression patterns of OzVR genes in different tissues and seasons indicated that OzVRs have the highest level of expression in the vomeronasal organ, and OzV1Rs notably higher in the breeding season than that in the non-breeding season, however the expression levels of OzV2Rs were higher in the non-breeding season. This study provided insights into the phylogenetic relationships, gene structure, physicochemical properties, promoter binding sites, functions and gene expression patterns of OzVRs, offering a theoretical reference for further examination of VR gene functions and a foundation for understanding chemical signaling mechanisms in the muskrat.

Anatomical and molecular development of the human primary visual cortex.

The human primary visual cortex (V1) development is pivotal to understanding cortical maturation and neuroplasticity. Theories on V1 development range from early maturation models, which emphasize the early peak of synapses in infancy, to those suggesting an extended developmental timeline where key plasticity mechanisms continue to mature well into adulthood. Classic histological approaches have supported early development, while recent molecular studies highlight prolonged or multiple windows of plasticity, indicating that V1 remains susceptible to experience-dependent modifications beyond childhood. This review consolidates findings from both anatomical and molecular studies, tracing the development of V1 from prenatal stages through aging. The evidence reveals that human V1 develops across multiple timescales, with some aspects maturing early and others gradually changing across the lifespan. Reflecting on Cajal's early work, this review underscores the importance of methodological advancements in revealing the intricate details of V1's development.

Standardized intermittent shoreline boat electrofishing for slow-flowing rivers in Sweden.

Electrofishing is a common method for sampling fish in rivers. In Sweden, electrofishing has a long history, dating back to the 1950s, but the vast majority of surveys have been conducted by wading in shallow river stretches, leaving a data gap for non-wadable rivers. Boat electrofishing allows for surveys in deeper river sections, but limited numbers of operational electrofishing boats have led to standardisation of methods not being prioritized within Swedish water management. This method protocol describes the first Swedish standardised method for boat electrofishing, based on intermittent shoreline sampling in larger slow-flowing rivers. The paper describes:•General methodology for boat electrofishing operation•Data collection protocols•Discussion of current caveats for the methodIn the future, the methodology will be amended to cover a wider array of river types (e.g. faster flowing river sections). Hence, readers are advised to look for updates to the protocol.

Paleopteran molecular clock: Time drift and recent acceleration.

Applying BEAST v1.10.4, we constructed a Bayesian Inference tree comprising 322 taxa, primarily representing Paleoptera (Odonata and Ephemeroptera; Pterygota), Zygentoma and Archaeognatha (Apterygota; paraphyly), and Neoptera (Plecoptera; Pterygota), based on a 2685 bp sequence dataset. Our analyses revealed that robust dating required the incorporation of both Quaternary and pre-Quaternary dates. To achieve this, our dating incorporated a 1.55 Ma (Quaternary) geological event (the formation of the Ryukyu Islands) and a set of chronologically well-founded fossil dates, spanning from up to 400 Ma (Devonian) for the stem Archaeognatha, 320 Ma (Carboniferous) for the crown of Paleoptera, 300 Ma (Carboniferous) for the crown Ephemeroptera, and 280 Ma (Permian) for the crown Odonata, down to 1.76 Ma (Quaternary) for Calopteryx japonica, encompassing a total of 22 calibration points (events: 6, fossils: 16; Quaternary: 7, pre-Quaternary: 15). The resulting dated tree aligns with previous research, albeit with some dates being overestimated. This overestimation was mainly due to the lack of Quaternary calibration and the exclusive dependence on pre-Quaternary calibration, though the application of maximum age constraints also played a role. Our minimum age dating demonstrates that the molecular clock did not uniformly progress, rendering rate dating an inapplicable approach. We observed that the base substitution rate is time-dependent, with an exponential increase evident from around 20 Ma (Miocene) to the present time, exceeding an order of magnitude. The extensive radiation and speciation of Insecta and Paleoptera, potentially resulting from the severe climatic changes associated with the Quaternary, including the commencement of glacial and interglacial cycles, may have significantly contributed to this increase in base substitution rates. Additionally, we identified a potential peak in base substitution rates during the Carboniferous period, around 320 million years ago, possibly corresponding to the Late Paleozoic Ice Age.

Unveiling the intricate role of S100A1 in regulating RyR1 activity: A commentary on "Structural insights into the regulation of RyR1 by S100A1".

S100A1, a calcium-binding protein, plays a crucial role in regulating Ca2+ signaling pathways in skeletal and cardiac myocytes via interactions with the ryanodine receptor (RyR) to affect Ca2+ release and contractile performance. Biophysical studies strongly suggest that S100A1 interacts with RyRs but have been inconclusive about both the nature of this interaction and its competition with another important calcium-binding protein, calmodulin (CaM). Thus, high-resolution cryo-EM studies of RyRs in the presence of S100A1, with or without additional CaM, were needed. The elegant work by Weninger et al. demonstrates the interaction between S100A1 and RyR1 through various experiments and confirms that S100A1 activates RyR1 at sub-micromolar Ca2+ concentrations, increasing the open probability of RyR1 channels.

Expanding the Spectrum of Autosomal Dominant ATP6V1A-Related Disease: Case Report and Literature Review.

BACKGROUND: Developmental and epileptic encephalopathies (DEE) are a group of disorders often linked to de novo mutations, including those in the ATP6V1A gene. These mutations, particularly dominant gain-of-function (GOF) variants, have been associated with a spectrum of phenotypes, ranging from severe DEE and infantile spasms to milder conditions like autism spectrum disorder and language delays. METHODS: We aim to expand ATP6V1A-related disease spectrum by describing a six-year-old boy who presented with a febrile seizure, mild intellectual disability (ID), language delay, acquired microcephaly, and dysmorphic features. RESULTS: Genetic analysis revealed a novel de novo heterozygous pathogenic variant (c.82G>A, p.Val28Met) in the ATP6V1A gene. He did not develop epilepsy, and neuroimaging remained normal over five years of follow-up. Although ATP6V1A mutations have traditionally been linked to severe neurodevelopmental disorders, often with early-onset epilepsy, they may exhibit milder, non-progressive phenotypes, challenging previous assumptions about the severity of ATP6V1A-related conditions. CONCLUSIONS: This case expands the known clinical spectrum, illustrating that not all patients with ATP6V1A mutations exhibit severe neurological impairment or epilepsy and underscoring the importance of including this gene in differential diagnoses for developmental delays, especially when febrile seizures or dysmorphic features are present. Broader genotype-phenotype correlations are essential for improving predictive accuracy and guiding clinical management, especially as more cases with mild presentations are identified.

ATP6V1D drives hepatocellular carcinoma stemness and progression via both lysosome acidification-dependent and -independent mechanisms.

Metabolic reprogramming is pivotal in cancer stem cell (CSC) self-renewal. However, the intricate regulatory mechanisms governing the crosstalk between metabolic reprogramming and liver CSCs remain elusive. Here, using a metabolic CRISPR-Cas9 knockout screen, we identify ATP6V1D, a subunit of the vacuolar-type H+-translocating ATPase (V-ATPase), as a key metabolic regulator of hepatocellular carcinoma (HCC) stemness. Elevated ATP6V1D expression correlates with poor clinical outcomes in HCC patients. ATP6V1D knockdown inhibits HCC stemness and malignant progression both in vitro and in vivo. Mechanistically, ATP6V1D enhances HCC stemness and progression by maintaining macroautophagic/autophagic flux. Specifically, ATP6V1D not only promotes lysosomal acidification, but also enhances the interaction between CHMP4B and IST1 to foster ESCRT-III complex assembly, thereby facilitating autophagosome-lysosome fusion to maintain autophagic flux. Moreover, silencing CHMP4B or IST1 attenuates HCC stemness and progression. Notably, low-dose bafilomycin A1 targeting the V-ATPase complex shows promise as a potential therapeutic strategy for HCC. In conclusion, our study highlights the critical role of ATP6V1D in driving HCC stemness and progression via the autophagy-lysosomal pathway, providing novel therapeutic targets and approaches for HCC treatment.Abbreviations: 3-MA: 3-methyladenine; ANT: adjacent normal liver tissues; ATP6V1D: ATPase H+ transporting V1 subunit D; BafA1: bafilomycin A1; CHMP: charged multivesicular body protein; co-IP: co-immunoprecipitation; CSC: cancer stem cell; ESCRT: endosomal sorting complex required for transport; HCC: hepatocellular carcinoma; IF: immunofluorescence; IHC: immunohistochemical; LCSCs: liver cancer stem cells; qRT-PCR: quantitative real time PCR; V-ATPase: vacuolar-type H+- translocating ATPase; WB: western blot.

Discovery and evaluation of a novel 18F-labeled vasopressin 1a receptor PET ligand with peripheral binding specificity.

The arginine-vasopressin (AVP) hormone plays a pivotal role in regulating various physiological processes, such as hormone secretion, cardiovascular modulation, and social behavior. Recent studies have highlighted the V1a receptor as a promising therapeutic target. In-depth insights into V1a receptor-related pathologies, attained through in vivo imaging and quantification in both peripheral organs and the central nervous system (CNS), could significantly advance the development of effective V1a inhibitors. To address this need, we develop a novel V1a-targeted positron emission tomography (PET) ligand, [18F]V1A-2303 ([18F]8), which demonstrates favorable in vitro binding affinity and selectivity for the V1a receptor. Specific tracer binding in peripheral tissues was also confirmed through rigorous cell uptake studies, autoradiography, biodistribution assessments. Furthermore, [18F]8 was employed in PET imaging and arterial blood sampling studies in healthy rhesus monkeys to assess its brain permeability and specificity, whole-body distribution, and kinetic properties. Our research indicated [18F]8 as a valuable tool for noninvasively studying V1a receptors in peripheral organs, and as a foundational element for the development of next-generation, brain-penetrant ligands specifically designed for the CNS.

Immune correlates analysis of the Imbokodo (HVTN 705/HPX2008) efficacy trial of a mosaic HIV-1 vaccine regimen evaluated in Southern African people assigned female sex at birth: a two-phase case-control study.

BACKGROUND: The HVTN 705 Imbokodo trial of 2636 people without HIV and assigned female sex at birth, conducted in southern Africa, evaluated a heterologous HIV-1 vaccine regimen: mosaic adenovirus 26-based vaccine (Ad26.Mos4.HIV) at Months 0, 3, 6, 12 and alum-adjuvanted clade C gp140 at Months 6, 12. Per-protocol vaccine efficacy (VE) against HIV-1 diagnosis from seven to 24 months was 14.1% (95% CI: -22.0% to 39.5%). Immune correlates analysis was performed for markers selected based on prior evidence in efficacy trials and/or nonhuman primate models. METHODS: Humoral and cellular immune response markers at Month 7 were evaluated as immune correlates of risk and of protection in a breakthrough case-control cohort (n = 52 cases, 246 non-cases). Primary markers were IgG binding to vaccine-strain gp140, IgG3 binding to diverse Env antigens (IgG3 Env breadth), IgG3 binding to diverse V1V2 antigens (IgG3 V1V2 breadth), antibody-dependent phagocytosis against the vaccine-strain gp140, Env-specific CD4+ and CD8+ T-cell responses, and multi-epitope functions. FINDINGS: No immune markers were statistically significant correlates of risk. IgG3 V1V2 breadth trended toward an inverse association: hazard ratio 0.70 (95% CI: 0.36 to 1.35; p = 0.29) per 10-fold increase and 0.51 (95% CI: 0.21 to 1.24; p = 0.14) in a Cox model with all primary markers. The VE estimate was 11.8% (95% CI: -17.9% to 34.0%) at all IgG3 V1V2 breadth values below 667 weighted geometric mean net MFI; just above this value, the VE estimate sharply increased to 62.6% (95% CI: -17.9% to 89.6%), and further increased to 80.9% (95% CI: -17.9% to 99.5%) at 1471 MFI, the 95th percentile of the marker distribution. Mediation analysis yielded a VE of 35.7% (95% CI: 15.0% to 51.3%) attributable to the vaccine's impact on this marker. INTERPRETATION: The trend in association of greater IgG3 V1V2 antibody breadth with lower likelihood of HIV acquisition is consistent with the identification of antibodies against V1V2 as immune correlates in three other HIV vaccine efficacy trials and suggests that a greater emphasis should be placed on studying this region in the HIV-1 envelope as a vaccine immunogen. FUNDING: National Institute of Allergy and Infectious Diseases and Janssen Vaccines & Prevention BV.

Exploring SCN5A variants associated with atrial fibrillation in atrial cardiomyocytes derived from human induced pluripotent stem cells: A characterization study.

BACKGROUND: Atrial fibrillation (AF) poses a major risk for heart failure, myocardial infarction, and stroke. Several studies have linked SCN5A variants to AF, but their precise mechanistic contribution remains unclear. Human induced pluripotent stem cells (hiPSCs) provide a promising platform for modeling AF-linked SCN5A variants and their functional alterations. OBJECTIVE: The purpose of this study was to assess the electrophysiological impact of 3 AF-linked SCN5A variants (K1493R, M1875T, N1986K) identified in 3 unrelated individuals. METHODS: CRISPR-Cas9 was used to generate a new hiPSC line in which NaV1.5 was knocked out. Following differentiation into specific atrial cardiomyocyte by using retinoic acid, the adult wild-type (WT) and 3 AF variants were introduced into the NaV1.5 knockout (KO) line through transfection. Subsequent analysis including molecular biology, optical mapping, and electrophysiology were performed. RESULTS: The absence of NaV1.5 channels altered the expression of key cardiac genes. NaV1.5 KO atrial-like cardiomyocytes derived from human induced pluripotent stem cells displayed slower conduction velocities, altered action potential (AP) parameters, and impaired calcium transient propagation. The transfection of the WT channel restored sodium current density, AP characteristics and the expression of several cardiac genes. Among the AF variants, 1 induced a loss of function (N1986K) while the other 2 induced a gain of function in NaV1.5 channel activity. Cellular excitability alterations and early afterdepolarizations were observed in AF variants. CONCLUSION: Our findings suggest that distinct alterations in NaV1.5 channel properties may trigger altered atrial excitability and arrhythmogenic activity in AF. Our KO model offers an innovative approach for investigating SCN5A variants in an adult human cardiac environment.

The V-ATPase/ATG16L1 axis is controlled by the V1H subunit.

Defects in organellar acidification indicate compromised or infected compartments. Recruitment of the autophagy-related ATG16L1 complex to pathologically neutralized organelles targets ubiquitin-like ATG8 molecules to perturbed membranes. How this process is coupled to proton gradient disruption is unclear. Here, we reveal that the V1H subunit of the vacuolar ATPase (V-ATPase) proton pump binds directly to ATG16L1. The V1H/ATG16L1 interaction only occurs within fully assembled V-ATPases, allowing ATG16L1 recruitment to be coupled to increased V-ATPase assembly following organelle neutralization. Cells lacking V1H fail to target ATG8s during influenza infection or after activation of the immune receptor stimulator of interferon genes (STING). We identify a loop within V1H that mediates ATG16L1 binding. A neuronal V1H isoform lacks this loop and is associated with attenuated ATG8 targeting in response to ionophores in primary murine and human iPSC-derived neurons. Thus, V1H controls ATG16L1 recruitment following proton gradient dissipation, suggesting that the V-ATPase acts as a cell-intrinsic damage sensor.

Identifying key pathogenic mechanisms and potential intervention targets for recurrence after laryngeal cancer treatment through bioinformatics screening.

Background: Laryngeal cancer (LC), a prevalent malignant tumor of the head and neck, is characterized by a high rate of postoperative recurrence and significant treatment challenges upon recurrence, severely impacting patients' quality of life. There is a pressing need for effective biomarkers in clinical practice to predict the risk of LC recurrence and guide the development of personalized treatment plans. This study uses bioinformatics methods to explore potential biomarkers for LC recurrence, focusing on key genes and exploring their functions and mechanisms of action in LC recurrence. The aim is to provide new perspectives and evidence for clinical diagnosis, prognostic evaluation, and targeted treatment of LC. Methods: Gene expression profiles from the GSE25727 data set in the Gene Expression Omnibus database were analyzed to detect the differentially expressed genes (DEGs) between the tumor tissues of postoperative recurrent and non-recurrent early stage LC patients. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were also conducted. A protein-protein interaction (PPI) network and transcription factor (TF)-DEG-microRNA (miRNA) network were developed using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database, with key genes selected using the Molecular Complex Detection (MCODE) plugin. A Gene Set Enrichment Analysis (GSEA) was carried out to investigate the possible mechanisms of the key genes. A retrospective analysis was conducted using the clinical data of 83 LC patients. Immunohistochemical staining was used to examine the transcription level of the key genes in the LC tumor tissues and the factors affecting postoperative recurrence. Results: A total of 248 upregulated and 34 downregulated DEGs were identified in the GSE25727 data set. The PPI network analysis identified a significant module and five candidate genes (i.e., RRAGA, SLC38A9, WDR24, ATP6V1B1, and LAMTOR3). The construction of the TF-DEG-miRNA network indicated that ATP6V1B1 might be regulated by one TF and interact with 17 miRNAs. The KEGG and GSEA analyses suggested that ATP6V1B1 may influence LC recurrence through the involvement of pro-inflammatory and pro-fibrotic mediators, glutathione metabolism, matrix metalloproteinases, immune regulation, and lymphocyte interactions. The recurrence rate of the 83 LC patients included in the study was 19.3% (16/83). The immunohistochemistry results indicated that ATP6V1B1 was highly expressed in patients with recurrent LC. The univariate and multivariate logistic regression analyses revealed that tumor stage T3 (P=0.04), tumor stage T4 (P=0.01), and a high expression of ATP6V1B1 (P=0.02) were risk factors for recurrence after surgical treatment in LC patients. Conclusions: The key genes and signaling pathways identified through the bioinformatics screening provide insights into the potential mechanisms of the pathogenesis of LC. ATP6V1B1 may promote the recurrence of LC by weakening the immune phenotype. Our findings provide a theoretical basis for further research into clinical diagnostics and treatment strategies for LC.

Reducing the solubility of the major birch pollen allergen Bet v 1 by particle-loading mitigates Th2 responses.

BACKGROUND: Solubility is a common feature of allergens. However, the causative relationship between this protein-intrinsic feature and sensitization capacity of allergens is not fully understood. This study aimed to proof the concept of solubility as a protein intrinsic feature of allergens. METHODS: The soluble birch pollen allergen Bet v 1 was covalently coupled to 1 µm silica particles. IgE-binding and -cross-linking capacity was assessed by inhibition ELISA and mediator release assay, respectively. Alterations in adjuvanticity by particle-loading were investigated by activation of dendritic cells, mast cells and the Toll-like receptor 4 pathway as well as by Th2 polarization in an IL-4 reporter mouse model. In BALB/c mice, particle-loaded and soluble Bet v 1 were compared in a model of allergic sensitization. Antigen uptake and presentation was analysed by restimulating human Bet v 1-specific T cell lines. RESULTS: Covalent coupling of Bet v 1 to silica particles resulted in an insoluble antigen with retained IgE-binding and -cross-linking capacity and no increase in adjuvanticity. In vivo, particle-loaded Bet v 1 induced significantly lower Bet v 1-specific (s)IgE, whereas sIgG1 and sIgG2a levels remained unaffected. The ratio of Th2 to Th1 cells was significantly lower in mice sensitized with particle-loaded Bet v 1. Particle-loading of Bet v 1 resulted in a 24-fold higher T cell activation capacity in Bet v 1-specific T cell lines, indicating more efficient uptake and presentation than of soluble Bet v 1. CONCLUSIONS: Our results show that solubility is a decisive factor contributing to the sensitization capacity of allergens. The reduction in sensitization capacity of insoluble, particle-loaded antigens results from enhanced antigen uptake and presentation compared to soluble allergens.

Is Hysteroscopic Metroplasty Advisable for U2bC2V1 Malformation?

A complete uterine septum, with a double cervix and vaginal septum, is a complex and rare congenital genital tract anomaly. The diagnosis is difficult and often challenging, requiring complex imaging investigations and diagnostic hysteroscopy. The benefit of hysteroscopic metroplasty for this uterine malformation is still the subject of dispute. However, the potential benefits of obtaining pregnancies and reducing the rate of abortions make this surgical method a desirable one. We present a series of three cases with U2bC2V1 malformation that were diagnosed via magnetic resonance imaging (MRI), in which hysteroscopic removal of the uterine septum and resection of the longitudinal vaginal septum were performed, with the preservation of the two cervixes. All patients became pregnant after the hysteroscopic intervention and reported an improvement in dyspareunia and dysmenorrhea.

V1bR enhances glucose-stimulated insulin secretion by paracrine production of glucagon which activates GLP-1 receptor.

BACKGROUND: Arginine vasopressin (AVP) has been reported to regulate insulin secretion and glucose homeostasis in the body. Previous study has shown that AVP and its receptor V1bR modulate insulin secretion via the hypothalamic-pituitary-adrenal axis. AVP has also been shown to enhance insulin secretion in islets, but the exact mechanism remains unclear. RESULTS: In our study, we unexpectedly discovered that AVP could only stimulates insulin secretion from islets, but not ß cells, and AVP-induced insulin secretion could be blocked by V1bR selective antagonist. Single-cell transcriptome analysis identified that V1bR is only expressed by the α cells. Further studies indicated that activation of the V1bR stimulates the α cells to secrete glucagon, which then promotes glucose-dependent insulin secretion from ß cells in a paracrine way by activating GLP-1R but not GCGR on these cells. CONCLUSIONS: Our study revealed a crosstalk between α and ß cells initiated by AVP/V1bR and mediated by glucagon/GLP-1R, providing a mechanism to develop new glucose-controlling therapies targeting V1bR.

Dominantly acting variants in ATP6V1C1 and ATP6V1B2 cause a multisystem phenotypic spectrum by altering lysosomal and/or autophagosome function.

The vacuolar H+-ATPase (V-ATPase) is a functionally conserved multimeric complex localized at the membranes of many organelles where its proton-pumping action is required for proper lumen acidification. The V-ATPase complex is composed of several subunits, some of which have been linked to human disease. We and others previously reported pathogenic dominantly acting variants in ATP6V1B2, the gene encoding the V1B2 subunit, as underlying a clinically variable phenotypic spectrum including dominant deafness-onychodystrophy (DDOD) syndrome, Zimmermann-Laband syndrome (ZLS), and deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizures (DOORS) syndrome. Here, we report on an individual with features fitting DOORS syndrome caused by dysregulated ATP6V1C1 function, expand the clinical features associated with ATP6V1B2 pathogenic variants, and provide evidence that these ATP6V1C1/ATP6V1B2 amino acid substitutions result in a gain-of-function mechanism upregulating V-ATPase function that drives increased lysosomal acidification. We demonstrate a disruptive effect of these ATP6V1B2/ATP6V1C1 variants on lysosomal morphology, localization, and function, resulting in a defective autophagic flux and accumulation of lysosomal substrates. We also show that the upregulated V-ATPase function affects cilium biogenesis, further documenting pleiotropy. This work identifies ATP6V1C1 as a new gene associated with a neurodevelopmental phenotype resembling DOORS syndrome, documents the occurrence of a phenotypic continuum between ZLS, and DDOD and DOORS syndromes, and classify these conditions as lysosomal disorders.

Neuronal and Behavioral Responses to Naturalistic Texture Images in Macaque Monkeys.

The visual world is richly adorned with texture, which can serve to delineate important elements of natural scenes. In anesthetized macaque monkeys, selectivity for the statistical features of natural texture is weak in V1, but substantial in V2, suggesting that neuronal activity in V2 might directly support texture perception. To test this, we investigated the relation between single cell activity in macaque V1 and V2 and simultaneously measured behavioral judgments of texture. We generated stimuli along a continuum between naturalistic texture and phase-randomized noise and trained two macaque monkeys to judge whether a sample texture more closely resembled one or the other extreme. Analysis of responses revealed that individual V1 and V2 neurons carried much less information about texture naturalness than behavioral reports. However, the sensitivity of V2 neurons, especially those preferring naturalistic textures, was significantly closer to that of behavior compared with V1. The firing of both V1 and V2 neurons predicted perceptual choices in response to repeated presentations of the same ambiguous stimulus in one monkey, despite low individual neural sensitivity. However, neither population predicted choice in the second monkey. We conclude that neural responses supporting texture perception likely continue to develop downstream of V2. Further, combined with neural data recorded while the same two monkeys performed an orientation discrimination task, our results demonstrate that choice-correlated neural activity in early sensory cortex is unstable across observers and tasks, untethered from neuronal sensitivity, and therefore unlikely to directly reflect the formation of perceptual decisions.

Population coding for figure-ground texture segregation in macaque V1 and V4.

Object recognition often involves the brain segregating objects from their surroundings. Neurophysiological studies of figure-ground texture segregation have yielded inconsistent results, particularly on whether V1 neurons can perform figure-ground texture segregation or just detect texture borders. To address this issue from a population perspective, we utilized two-photon calcium imaging to simultaneously record the responses of large samples of V1 and V4 neurons to figure-ground texture stimuli in awake, fixating macaques. The average response changes indicate that V1 neurons mainly detect texture borders, while V4 neurons are involved in figure-ground segregation. However, population analysis (SVM decoding of PCA-transformed neuronal responses) reveal that V1 neurons not only detect figure-ground borders, but also contribute to figure-ground texture segregation, although requiring substantially more principal components than V4 neurons to reach a 75 % decoding accuracy. Individually, V1/V4 neurons showing larger (negative/positive) figure-ground response differences contribute more to figure-ground segregation. But for V1 neurons, the contribution becomes significant only when many principal components are considered. We conclude that V1 neurons participate in figure-ground segregation primarily by defining the figure borders, and the poorly structured figure-ground information V1 neurons carry could be further utilized by V4 neurons to accomplish figure-ground segregation.