Biology subjects

Castro, J.

Publications and source records attributed to Castro, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Odor representations are structured by heterogeneous tuning and concentration-dependence of functionally distinct olfactory sensory neuron subpopulations.

Olfactory stimuli (odorants) are represented by combinatorial patterns of olfactory sensory neuron (OSN) activation that are translated into spatially-organized glomerular maps at their input to the CNS. How glomerular maps relate to odorant features - including chemical structure and concentration - remains a key question in understanding the neural mechanisms of odor coding. Here, we compared glomerular response maps for the same 59 odorants across three concentration regimes, using GCaMP6 imaging from OSN axon terminals in the olfactory bulb (OB) of the anesthetized mouse. At the lowest regime, in which concentrations were chosen to distinguish the most sensitive glomeruli for each odorant, glomeruli were exceptionally narrowly tuned and responses across glomeruli were extremely sparse. We then compared responses at two higher-concentration regimes, 'low' and 'high', differing by 25-fold from each other and 2 - 5 log units higher than the 'most-sensitive' regime. Increasing concentration broadened tuning of OSN inputs; this broadening was heterogeneous across chemical space and was well-described by classifying glomeruli into several subpopulations with distinct consensus tuning profiles. Each subpopulation was selectively tuned to one or a few odorant chemical classes and spatially clustered in a manner consistent with the projection patterns of receptor-defined OSN classes. Glomerular subpopulations retained distinct tuning and spatial localization even at the highest concentrations. OSN subpopulations thus sample chemical space nonuniformly across a large concentration range. These results suggest a lower-dimensional structure in the representation of odorant information that largely reflects OSN subpopulations which, in turn, map to olfactory receptor subfamilies. This organization may enable distinct odor coding strategies for different OSN classes and for parts of chemical feature space with distinct ethological relevance.

neuroscience↗

bioRxiv2026

Adaptations of the pregnant murine heart to pre-existing hypertension

2-5% of pregnancies are complicated by chronic hypertension [1], increasing the risk of peripartum cardiomyopathy and maternal morbidity [2, 3]. Hypertension reduces stroke volume, whereas pregnancy increases stroke volume. The combined impact of these opposing loads on cardiac function and strain remains unclear. We used a mouse model of pregnancy with pre-existing hypertension to characterize cardiac remodeling. We hypothesized that pregnancy may counteract hypertension-related reductions in cardiac function. Nulliparous female C57Bl6/J mice (7-11 weeks old) were assigned into pregnant (PREG, n=11), angiotensin II-treated (ANGII, n=7), and ANGII+PREG (n=8) groups. Hypertension was induced with subcutaneous angII infusion (1000 ng/kg/min). Cardiac function was measured with high-frequency ultrasound. Ejection fraction (EF) was maintained in PREG animals at 65% but decreased significantly by day 36 in ANGII animals (44.85{+/-}3.27%). In ANGII+PREG mice, EF initially decreased but trended towards PREG values on postpartum day 1. Left ventricle strain was lower in ANGII and ANGII+PREG groups compared to PREG. ANGII and ANGII+PREG animals showed decreased early longitudinal diastolic strain rate at mid-pregnancy compared to baseline (0.82{+/-}0.09% ANGII; 0.73{+/-}0.09% ANGII+PREG), while increasing in PREG (1.76{+/-}0.14%). Minimal physiologically relevant fibrosis was noted across groups via immunohistochemistry. Heart mass-to-body mass was lowest in PREG (6.20{+/-}0.22 mg/g), greatest in ANGII (8.95{+/-}0.39 mg/g), and intermediate in ANGII+PREG (6.92{+/-}0.25 mg/g). Cardiomyocyte cross-sectional area was similar between groups. Overall, pregnancy altered the functional and hypertrophic response to elevated blood pressure. Findings from this work set the foundation for future efforts that may eventually improve cardiovascular care for pregnant patients.

bioengineering↗

bioRxiv2026

Enhanced Pathogenicity and Contact Transmissibility of Human-origin Avian Influenza H5N1 Clade 2.3.4.4b Genotype B3.13 Compared to D1.1 in Ferrets

Since its emergence in 2020, multiple genotypes of the H5N1 clade 2.3.4.4b have been identified, with B3.13 and D1.1 emerging in the USA as two major and concerning genotypes. However, their relative pathogenicity and transmissibility in mammals have not been fully elucidated. We compared the pathogenicity and transmissibility of the first two human H5N1 clade 2.3.4.4b cases caused by B3.13 in Texas (A/Texas/37/2024; HPhTX B3.13) and D1.1 in Louisiana (A/Louisiana/12/2024; HPhLA D1.1) in a ferret model of infection and transmission. HPhTX B3.13 infection resulted in more severe clinical disease and enhanced viral shedding, with evidence of increased transmission relative to HPhLA D1.1. Histopathological analysis revealed more extensive lung pathology in animals infected with HPhTX B3.13, consistent with increased viral loads and inflammatory responses. Importantly, both genotypes showed no significant differences in reactivity to ferret sera raised against candidate vaccine virus (CVV) strains, receptor binding properties, or neuraminidase (NA) activity and thermostability. Whole-genome sequencing revealed no adaptive mutations in HPhTX B3.13 following infection or transmission. In contrast, HPhLA D1.1 showed rapid acquisition of the mammalian-adaptive mutation E627K in infected ferrets and both E627K and Q194K in the only fatal contact animal. Both mutations were associated with enhanced polymerase activity and computational analyses suggested that they enhance interactions with the mammalian host factors ANP32A and B. Our findings indicate that B3.13 is already well adapted for mammalian infection and transmission whereas D1.1 retains evolutionary potential through the rapid acquisition of adaptive mutations, highlighting important genotype-specific differences relevant to zoonotic risk assessment and pandemic preparedness. SignificanceInfluenza H5N1 viruses continue to diversify genetically while expanding into mammalian hosts, increasing opportunities for viral adaptation and zoonotic transmission, including humans. However, whether the predominant clade 2.3.4.4b genotype differs in its capacity to infect, transmit, and evolve in mammals remains poorly understood. Using the ferret model of influenza infection and transmission, we demonstrated that the currently circulating B3.13 and D1.1 genotypes exhibit distinct pathogenic and transmission characteristics despite retaining similar receptor-binding characteristics, NA functions, and antigenic profiles. While B3.13 readily infects and transmits in ferrets and does not develop further adaptive mutations associated with increased replication and transmission, D1.1 rapidly acquires mammalian-adaptive mutations after a single infection and/or transmission event, highlighting its evolutionary potential. These findings show that genotype-specific biological properties can influence zoonotic risk independently of antigenic similarity and emphasize the importance of integrating phenotypic characterization with genomic surveillance to improve pandemic preparedness and guide public health risk assessment.

microbiology↗

bioRxiv2026

Census and genetic analysis of the United States marmoset population

The common marmoset (Callithrix jacchus), a small monkey native to Brazil, has been used as a biomedical model in the United States (US) since the 1950s, yet the origins, genomic diversity, and population structure of current colonies remain poorly defined. Through the NIH Marmoset Coordinating Center, we registered and sampled most US research marmosets ([~]2,300 living animals) and assembled pedigrees and historical records for >10,000 individuals. We present a resource of >800 whole-genome sequences, largely from US colonies. These data reveal an unexpected population structure that predates the establishment of research colonies. Indeed, this population structure mirrors variation found in marmosets across Brazil. Leveraging sequenced families, we generate the first pedigree-based recombination map and improved estimates of de novo mutation processes for this species. Our insights into genetic diversity, structure, and inbreeding will guide colony management, inform disease modelling and strengthen the marmosets standing as a biomedical model. Further, this work demonstrates how coordinated efforts across colonies can enable a self-sustaining "living laboratory", supporting data sharing and well-powered studies beyond the reach of single institutions.

genetics↗

bioRxiv2026

STARMAP: A 3D-informed framework for mapping functional regions in proteins to regulatory and cellular phenotypes

Artificial Intelligence (AI) has transformed biology by revealing patterns in large-scale datasets and predicting regulatory relationships. Yet even the most advanced models often fail to identify biologically meaningful mechanisms from statistical associations. This limitation arises not from algorithmic capacity but from the lack of mechanistically grounded input features. Our structure-informed framework Structure-based Topological Analysis of Regulatory and Molecular Activity Patterns (STARMAP) embeds protein three-dimensional structure and population-scale functional genomics data into a unified representation for mechanistic inference. By mapping over 1.5 million naturally occurring variants across [~]1,700 cancer cell lines onto protein structures, STARMAP was able to identify spatial clusters of variation associated with shifts in transcriptional regulatory networks and drug response phenotypes. This approach transforms natural genetic variation into a large-scale, structure-informed screen, enabling systematic discovery of regulatory relationships across the proteome and providing interpretable and testable models of cellular regulation.

genomics↗

bioRxiv2025

Spatiotemporal data integration for marine megafauna SDMs in dynamic environments: A point process approach

Species distribution models (SDMs) are widely used to predict where and when species occur, but the data available to fit them often resolve space and time unevenly. Designed surveys, such as line-transect distance-sampling surveys, provide structured spatial coverage and the detection information needed to estimate detectability, but logistical and funding constraints often limit them to short, infrequent periods. Opportunistic or citizen-science records are collected more frequently across the year, but from areas shaped by observer access and interest rather than survey design, and usually without comparable detection information. As a result, models built from either source alone tend to capture spatial structure or temporal dynamics well, but not both, limiting predictions for mobile species in dynamic environments. Here, we present a general framework, based on a log-Gaussian Cox process (LGCP) fitted using integrated nested Laplace approximations (INLA), that links multiple data sources to a shared spatiotemporal measure of species density through source-specific observation models: a detection function for survey transects, and spatial constraints reflecting the footprint of opportunistic effort. We apply the framework to cetacean line-transect surveys and whale-watching records. In a simulation with one month of survey data and twelve months of opportunistic data, the integrated model recovered spatiotemporal distribution patterns well (median correlation with the true pattern = 0.91) and estimated monthly abundance with a mean error of +10.7%, outperforming single-source models. In a case study of common dolphins (Delphinus delphis) off mainland Portugal, integration improved the spatial accuracy of predictions, although weak covariate effects limited the temporal variation the model could resolve. These results show that integration adds the most value when the two data sources resolve complementary aspects of distribution, in this case broad spatial structure from the survey and temporal replication from whale-watching, while temporal predictions remain limited when covariates carry weak seasonal signal. The framework is general and can be extended to other taxa, systems, and combinations of structured and opportunistic data by substituting the relevant observation models.

ecology↗

bioRxiv2025

Pro-endometriosis macrophage release of IL-33 is key for endometriosis pain and lesion formation

Endometriosis is a painful gynecological inflammatory disease affecting up to 10% of females. When released by sensory neurons, calcitonin gene-related peptide (CGRP) shapes immunity, a process known as neuroimmune communication. We previously showed that nociceptor-derived CGRP polarizes macrophages into pro-endometriosis macrophages (PEMs) that mediates endometrial epithelial (endo-epi) cell proliferation and pain. However, the key mediators involved in this PEM-induced cell proliferation were unknown. Using unbiased approaches, we discovered that nociceptor-derived CGRP induces PEMs to produce IL-33. IL-33 binding to its receptor ST2 is key for endometriotic lesion growth and pain during endometriosis in mice as anti-IL-33 antibody treatment reduced evoked and spontaneous pain as well as lesion size. Chemical or genetic ablation of nociceptors or macrophages also resulted in lower levels of lesion IL-33, demonstrating a neuroimmune-driven mechanism for IL-33 production during endometriosis. In humans, we found that IL-33 is correlated with increased number of glands and fibrosis in lesions and that IL-33 expression in macrophages is also associated with genetic risk of endometriosis. We also provided evidence that suggests a dual role for IL-33 in endometriosis, in which, it is initially required for lesion formation and later for lesion maintenance only, and associated pain. Therefore, targeting IL-33/ST2 signaling may effectively treat endometriosis pain.

neuroscience↗

bioRxiv2025

Single dose alum adjuvanted RBD protein vaccine provides protection against homologous challenge with SARS-CoV-2 Washington strain and heterologous rechallenge with Delta and Omicron BA.5 variants in K18 hACE2 mouse model

Most COVID-19 vaccination strategies require at least two doses-a primary vaccine followed by a booster dose with the updated variant-specific vaccine. However, vaccine and booster dose hesitancy make it challenging to administer multiple doses of vaccines in the unvaccinated and vaccinated populations, respectively. Thus, it is important to determine if vaccinated individuals exposed to SARS-CoV-2 infection develop immune responses that may protect them against emerging variants of concern (VoCs). We have developed mouse models to understand the protective efficacy of an RBD-based vaccine against challenge and rechallenge with SARS-CoV-2 VoCs. Mice were vaccinated with RBD protein vaccine formulated in 2% Alhydrogel (alum) adjuvant by subcutaneous route. To determine the efficacy of RBD vaccine, mice were challenged approximately 4 weeks post-vaccination with SARS-CoV-2 variants by intranasal route. To determine the efficacy of RBD vaccine against SARS-CoV-2 rechallenge, mice were rechallenged with SARS-CoV-2 Delta and Omicron BA.5 variants at day 14 post SARS-CoV-2 Washington (WA) strain challenge. Our data suggest that single dose alum adjuvanted RBD protein from Wuhan strain provides protection against homologous challenge with SARS-CoV-2 WA strain but failed to provide protection against heterologous challenge with Delta and Omicron BA.5 variants. Interestingly, vaccinated mice that survived homologous challenge with the WA strain showed protection against heterologous rechallenge with Delta and omicron BA.5 variants. Furthermore, infectious viral loads of Delta and Omicron BA.5 were not detected in the lung tissues collected from the rechallenged mice at 3 days post-rechallenge. The data suggest that a single dose RBD vaccine from the ancestral Wuhan strain together with survival from WA strain challenge induces protective immune responses against Delta and Omicron BA.5 variants rechallenge. These mouse models will be useful to determine the immune responses that correlate with protection against challenge and rechallenge with SARS-CoV-2 VoCs.

microbiology↗

bioRxiv2025

A Cellular Basis for Heightened Gut Sensitivity in Females

Visceral pain disorders, such as irritable bowel syndrome, exhibit a marked female prevalence. Enhanced signaling between enterochromaffin (EC) cells in the gut epithelium and mucosal sensory nerve fibers likely contributes to this sex bias. Here, we identify a novel estrogen-responsive paracrine pathway in which two enteroendocrine cell types, PYY-expressing L-cells and serotonergic EC cells, communicate to increase gut sensitivity in females. We demonstrate that ER estrogen signaling upregulates the bacterial metabolite SCFA receptor Olfr78 on colonic L-cells, increasing PYY release and their sensitivity to acetate. Elevated PYY acts on neighboring EC cells via NPY1R, thereby enhancing serotonin release and gut pain. We propose that hormonal fluctuations, in conjunction with internal (stress) or environmental (diet) factors, amplify this local estrogen-responsive colonic circuit, resulting in maladaptive gut sensitivity.

physiology↗

bioRxiv2024

The RNA from Pseudomonas aeruginosa impairs neutrophil responses favoring bacterial survival

Epithelial and endothelial cells are essential in the modulation of innate immune responses in the lung, including the arrival of neutrophils (PMN), which are crucial cells for the antibacterial host defense. These cells are exposed to prokaryotic RNA (pRNA) during bacterial infections and pRNA has been shown to promote or attenuate the inflammatory response on different immune cells. Pseudomonas aeruginosa (PAE) can cause severe pneumonia and has several immune-evading mechanisms. The aim of this study was to determine the effects of the RNA from PAE (RNAPAE) on lung epithelial, endothelial cells and PMN, and its impact on bacterial elimination. For this purpose, we purified total RNAPAE, and used it as a stimulus to evaluate different functions on Calu-6, HMEC-1 and isolated human PMN. We found that RNAPAE neither induced a pro-inflammatory response on Calu-6 or HMEC-1, as measured by ICAM-1 surface expression, or IL-6 and IL-8 secretion. Also, RNAPAE failed to activate PMN, as measured by forward-scatter (FSC) increase, CD11b surface expression, chemotaxis and IL-8 secretion. Pre-stimulation with RNAPAE diminished CD11b surface expression, chemotaxis and microbicidal activity when PMN were challenged with live bacteria. Moreover, we found that phagocytosis was affected in the presence of RNAPAE. Fragments of short RNA (<200 bp) were responsible for the PMN microbicidal attenuation during bacterial elimination. In conclusion, our results indicated that short fragments of RNAPAE diminished the immune response on PMN even in the presence of live bacteria. AUTHOR SUMMARYPseudomonas aeruginosa (PAE) pneumonia constitutes a major problem for human health. Therapies are frequently inefficient due to immune evasion mechanisms of PAE. Therefore, it is imperative to understand the relationship between PAE (or its components) with the immune system to improve therapeutic strategies. Since some bacterial RNA are immunosuppressive, our hypothesis was that the RNA from PAE (RNAPAE) might negatively modulate the immune response in a lung infection. We investigated the effects of the RNAPAE on lung epithelial, and microvascular endothelial cells, central cells that respond to PAE early during infection, and on neutrophils (PMN), the first immune cell that arrives at the site of infection. We found that RNAPAE failed to induce any response on pulmonary epithelium, endothelium, or PMN. Moreover, RNAPAE-treated PMN showed reduced migration, activation, and bactericidal response against live bacteria. Exploring deeper into this phenomenon, we found that increased bacterial survival was due to a lower phagocytic capacity of RNAPAE-treated PMN. Our results indicate that RNAPAE may act as another evasion strategy to favor PAEs survival in a pulmonary infection. Understanding the mechanisms by which PAE reduces the response of cells that participate in pulmonary immunity is crucial for planning interventions that may benefit infected patients.

immunology↗

bioRxiv2022

Modular gene interactions drive modular pan-genome evolution in bacteria.

Depending on the scale of observation, bacterial genomes are both organized and fluid. While individual bacterial genomes show signatures of organization (e.g., operons), pan-genomes reveal genome fluidity, both in terms of gene content and order (synteny). Here we ask how mutational forces (including recombination and horizontal gene transfer) combine with selection and gene interactions to shape genome organization and variation both within and across strains. We first build an evolutionary simulation model to assess the impact of gene interactions on pan-genome structure. A neutral evolutionary model can produce transient co-segregation of initially linked genes but is vulnerable on longer time-scales to perturbing mutational events. In contrast, incorporation of modular gene fitness interactions can produce sustainable clusters of linked and co-segregating genes, with the network of co-segregation recapitulating the defined simulation ground-truth network of gene interactions. To test our model predictions, we exploit the increasing number of closed genomes in model species to define gene co-segregation networks in the pan-genomes of Escherichia coli and Pseudomonas aeruginosa. Using these highly curated pan-genomes, we identify modular clusters of physically linked and co-segregating genes and show that the resulting co-segregation networks map onto underlying gene-regulatory and metabolic gene interaction networks. The results imply that co-segregation networks can contribute to accessory genome annotation, and more generally that gene interactions are the primary force shaping genome structure and operon evolution.

evolutionary biology↗

bioRxiv2022

The voltage-gated sodium channel NaV1.7 underlies endometriosis-associated chronic pelvic pain

Chronic pelvic pain (CPP) is the primary symptom of endometriosis patients, but adequate treatments are lacking. Modulation of ion channels expressed by sensory nerves innervating the viscera have shown promise for the treatment of irritable bowel syndrome and overactive bladder. However, similar therapies have not been explored for endometriosis-associated CPP. Here we examined the role of the voltage-gated sodium (NaV) channel NaV1.7 in the sensitivity of vagina-innervating sensory afferents and investigated whether NaV1.7 inhibition reduces nociceptive signals from the vagina and ameliorates endometriosis-associated CPP. The mechanical responsiveness of vagina-innervating sensory afferents was assessed with ex vivo single unit recording preparations. Pain evoked by vaginal distension (VD) was quantified by the visceromotor response (VMR) in vivo. In control mice, pharmacological activation of NaV1.7 with OD1 sensitised vagina-innervating pelvic afferents to mechanical stimuli. Using a syngeneic mouse model of endometriosis, we established that endometriosis sensitized vagina-innervating pelvic afferents to mechanical stimuli. The highly selective NaV1.7 inhibitor Tsp1a revealed that this afferent hypersensitivity occurred in a NaV1.7-dependent manner. Moreover, in vivo intra-vaginal treatment with Tsp1a reduced the exaggerated VMRs to VD that is characteristic of mice with endometriosis. Conversely, Tsp1a did not alter ex vivo afferent mechanosensitivity or in vivo VMRs to VD in Sham control mice. Collectively, these findings suggest that NaV1.7 plays a crucial role in endometriosis-induced vaginal hyperalgesia. Importantly, NaV1.7 inhibition selectively alleviated endometriosis-associated CPP without the loss of normal sensation, suggesting that selective targeting of NaV1.7 could improve the quality of life of women with endometriosis.

cell biology↗

bioRxiv2022

The evolution of two transmissible leukaemias colonizing the coasts of Europe

Transmissible cancers are malignant cell clones that spread among individuals through transfer of living cancer cells. Several such cancers, collectively known as bivalve transmissible neoplasia (BTN), are known to infect and cause leukaemia in marine bivalve molluscs. This is the case of BTN clones affecting the common cockle, Cerastoderma edule, which inhabits the Atlantic coasts of Europe and north-west Africa. To investigate the origin and evolution of contagious cancers in common cockles, we collected 6,854 C. edule specimens and diagnosed 390 cases of BTN. We then generated a reference genome for the species and assessed genomic variation in the genomes of 61 BTN tumours. Analysis of tumour-specific variants confirmed the existence of two cockle BTN lineages with independent clonal origins, and gene expression patterns supported their status as haemocyte-derived marine leukaemias. Examination of mitochondrial DNA sequences revealed several mitochondrial capture events in BTN, as well as co-infection of cockles by different tumour lineages. Mutational analyses identified two lineage-specific mutational signatures, one of which resembles a signature associated with DNA alkylation. Karyotypic and copy number analyses uncovered genomes marked by pervasive instability and polyploidy. Whole-genome duplication, amplification of oncogenes CCND3 and MDM2, and deletion of the DNA alkylation repair gene MGMT, are likely drivers of BTN evolution. Characterization of satellite DNA identified elements with vast expansions in the cockle germ line, yet absent from BTN tumours, suggesting ancient clonal origins. Our study illuminates the evolution of contagious cancers under the sea, and reveals long-term tolerance of extreme instability in neoplastic genomes.

evolutionary biology↗

bioRxiv2022

Gut Enterochromaffin Cells are Critical Drivers of Visceral Pain and Anxiety

Gastrointestinal (GI) discomfort is a hallmark of most gut disorders and represents a significant component of chronic visceral pain 1. For the growing population afflicted by irritable bowel syndrome (IBS), GI hypersensitivity and pain persist long after signs of tissue injury have resolved 2. IBS also exhibits a strong sex bias afflicting women three-fold more than men 1. Identifying the molecules, cells, and circuits that mediate both the acute and persistent phases of visceral pain is a critical first step in understanding how environmental and endogenous factors produce long-term changes in the nervous system or associated tissues to engender chronic pain syndromes 3,4. Enterochromaffin (EC) cells within the gut epithelium are exceedingly rare sensory neuroendocrine cells that detect and transduce noxious stimuli to nearby nerve endings via serotonin. Here, we manipulate murine EC cell activity using genetic strategies to ascertain their contributions to visceral pain. We show that acute EC cell activation is sufficient to elicit hypersensitivity to gut distension and necessary for the sensitizing actions of isovalerate, a bacterially derived short-chain fatty acid irritant associated with inflammatory GI disorders. Remarkably, prolonged EC cell activation by itself is sufficient to produce persistent visceral hypersensitivity, even in the absence of an instigating inflammatory episode. Perturbing the activity of these rare EC cells led to a marked increase in anxiety-like behaviors that normalized after blocking serotonergic signaling. Sex differences were also observed accross a range of assays indicating that females have a higher baseline visceral sensitivity. Our findings validate a critical role for EC cell-mucosal afferent signaling in acute and persistent GI pain while highlighting mechanistically defined genetic models for studying visceral hypersensitivity, sex differences, and associated behaviors.

physiology↗

bioRxiv2021

Neutralizing antibody-independent immunity to SARS-CoV-2 in hamsters and hACE-2 transgenic mice immunized with a RBD/Nucleocapsid fusion protein

The nucleocapsid (N) and the receptor binding domain (RBD) of the Spike (S) proteins elicit robust antibody and T cell responses either in vaccinated or COVID-19 convalescent individuals. We generated a chimeric protein that comprises the sequences of RBD from S and N antigens (SpiN). SpiN was highly immunogenic and elicited a strong IFN{gamma} response from T cells and high levels of antibodies to the inactivated virus, but no neutralizing antibodies. Importantly, hamsters and the human Angiotensin Convertase Enzyme-2-transgenic mice immunized with SpiN were highly resistant to challenge with the wild type SARS-CoV-2, as indicated by viral load, clinical outcome, lung inflammation and lethality. Thus, the N protein should be considered to induce T-cell-based immunity to improve SARS-CoV-2 vaccines, and eventually to circumvent the immune scape by variants.

immunology↗

bioRxiv2021

Longitudinal allometry of sulcal morphology in health and schizophrenia

Scaling between subcomponents of cortical folding and total brain volume (TBV) in healthy individuals (HI) is allometric, i.e. non-linear. It is unclear whether this is also true in individuals with schizophrenia (SZ) or first-episode psychosis (FEP). The current study first confirmed normative allometric scaling norms in HI using discovery and replication samples. Cross-sectional and longitudinal diagnostic differences in folding subcomponents were then assessed using an allometric analytic framework. Structural imaging from a longitudinal (sample 1: HI and SZ, nHI Baseline = 298, nSZ Baseline = 169, nHI Follow-up = 293, nSZ Follow-up = 168, a total of 1087 images, all individuals [≥] 2 images, age 16-69 years) and a cross-sectional sample (sample 2: nHI = 61 and nFEP = 89, age 10-30 years) is leveraged to calculate global folding and its nested subcomponents: sulcation index (SI, total sulcal/cortical hull area) and determinants of sulcal area; sulcal length and sulcal depth. Scaling of the SI, sulcal area, and sulcal length with TBV in SZ and FEP was allometric and did not differ from HI. Longitudinal age trajectories demonstrated steeper loss of SI and sulcal area through adulthood in SZ. Longitudinal allometric analysis revealed that both annual change in SI and sulcal area was significantly stronger related to change in TBV in SZ compared to HI. Our results detail the first evidence of the disproportionate contribution of changes in SI and sulcal area to TBV changes in SZ. Longitudinal allometric analysis of sulcal morphology provides deeper insight into lifespan trajectories of cortical folding in SZ.

neuroscience↗

bioRxiv2020

Activation of MrgprA3 and MrgprC11 on bladder-innervating afferents induces peripheral and central hypersensitivity to bladder distension

Understanding the sensory mechanisms innervating the bladder is paramount to developing efficacious treatments for chronic bladder hypersensitivity conditions. The contribution of Mas-gene-related G protein-coupled receptors (Mrgpr) to bladder signalling is currently unknown. Here we show in mice with single-cell RT-PCR that sub-populations of dorsal root ganglion (DRG) neurons innervating the mouse bladder express MrgprA3 (14%) and MrgprC11 (38%), either individually or in combination, with high levels of co-expression with Trpv1 (81-89%). Calcium imaging studies demonstrated MrgprA3 and MrgprC11 agonists (chloroquine, BAM8-22 and neuropeptide FF) activated sub-populations of bladder-innervating DRG neurons, showing functional evidence of co-expression between MrgprA3, MrgprC11 and TRPV1. In ex vivo bladder-nerve preparations chloroquine, BAM8-22 and neuropeptide FF all evoked mechanical hypersensitivity in sub-populations (20-41%) of bladder afferents. These effects were absent in recordings from Mrgpr-cluster{Delta}-/- mice. In vitro whole-cell patch clamp recordings showed that application of an MrgprA3/C11 agonist cocktail induced neuronal hyper-excitability in 44% of bladder-innervating DRG neurons. Finally, in vivo instillation of an MrgprA3/C11 agonist cocktail into the bladder of wild-type mice induced a significant activation of dorsal horn neurons within the lumbosacral spinal cord, as quantified by pERK-immunoreactivity. This MrgprA3/C11 agonist-induced activation was particularly apparent within the superficial dorsal horn and the sacral parasympathetic nuclei of wild-type, but not Mrgpr-cluster{Delta}-/- mice. This study demonstrates, for the first time, functional expression of MrgprA3 and MrgprC11 in bladder afferents. Activation of these receptors is not required for normal bladder function but does trigger hypersensitivity to distension, a critically valuable factor for therapeutic target development. Significance statementDetermining how bladder afferents become sensitized is the first step in finding effective treatments for common urological disorders such as overactive bladder and interstitial cystitis/bladder pain syndrome. Here we show that two of the key receptors, MrgprA3 and MrgprC11, that mediate itch from the skin are also expressed on afferents innervating the bladder. Activation of these receptors results in sensitization of bladder afferents, resulting in sensory signals being sent into the spinal cord that prematurely indicate bladder fullness. Targeting bladder afferents expressing MrgprA3 or MrgprC11 and preventing their sensitisation may provide a novel approach for treating overactive bladder and interstitial cystitis/bladder pain syndrome.

neuroscience↗

bioRxiv2020

Autoregulatory control of microtubule binding in the oncogene, doublecortin-like kinase 1

The microtubule-associated protein (MAP), doublecortin-like kinase 1 (DCLK1), is highly expressed in a range of cancers and is a prominent therapeutic target for the development of kinase inhibitors. However, the physiological roles of its kinase activity and how DCLK1 kinase activity is regulated remain elusive. Here we employ in vitro reconstitution with purified proteins to analyze the role of DCLK1 kinase activity in regulating microtubule binding. We find that DCLK1 autophosphorylates a single residue within its C-terminal tail to restrict its kinase activity and prevent aberrant hyperphosphorylation within its microtubule-binding domain. Removal of the C-terminal tail or mutation of this residue causes an increase in phosphorylation largely within the doublecortin 2 (DC2) domain, which dramatically reduces the microtubule affinity of DCLK1. Therefore, autophosphorylation at specific sites within DCLK1 have diametric effects on the molecules ability to associate with microtubules. Overall, our results suggest a mechanism by which DCLK1 modulates its own kinase activity to tune its microtubule binding affinity, providing molecular insights into a unique form of autoregulatory control over microtubule binding activity within the broader family of MAPs. These results provide useful molecular insights for future therapeutic efforts related to DCLK1s role in cancer development and progression.

biochemistry↗