Biology subjects

Magalhaes, A.

Publications and source records attributed to Magalhaes, A..

12 recordsLinked to original sources

bioRxiv2026

A 3D Tumor-on-a-chip Platform to Identify Drugs that Block Breast Cancer Cell Intravasation

Metastasis is the leading cause of death in breast cancer patients, yet there are no drugs specifically designed to block cancer cell intravasation, an early step of the metastatic cascade that originates circulating tumour cells (CTCs). A major challenge in developing anti-intravasation drugs is the scarcity of relevant in vitro platforms suitable for predictable drug discovery. Intravasation is a fundamental step of metastasis and involves the crossing of cancer cells through an endothelial barrier to enter the blood circulation. Here we developed an intravasation-on-a-chip model with controlled extracellular matrix composition, fluid flow and shear stress, which mimics the dynamic tumour-endothelium interface. The systems allows real-time imaging of intravasation and the isolation and quantification of intravasated cancer cells. As a proof-of-concept for drug testing, we show that perfusion with the PI3K/mTOR inhibitor Dactolisib, significantly reduced intravasation without compromising endothelial cell viability. The system also provides the capability to evaluate inhibitor on-target activity via imaging analysis. This intravasation-on-a-chip model offers a powerful, scalable, and imaging-compatible platform for discovering and evaluating anti-intravasation compounds.

cancer biology↗

bioRxiv2025

Meningeal γδ T cells facilitate bacterial entry into the brain in neonatal meningitis and trigger long-term behavioural sequelae

Neonatal bacterial meningitis is a life-threatening condition and a leading cause of neurodevelopmental impairment among survivors. Despite its prevalence, the role of meningeal immunity on disease pathology during early life remains largely unexplored. Using a clinically relevant mouse model of neonatal group B streptococcal meningitis and single-cell RNA sequencing, we observed that IL-17A (IL-17)-producing {gamma}{delta} T cells ({gamma}{delta}17 T cells) accumulate in the meninges during the acute phase of infection and persist throughout the lifespan. Importantly, mice deficient in {gamma}{delta} T cells or in IL-17 show a significantly lower bacterial colonisation in the brain parenchyma, and IL-17 neutralisation in the cerebrospinal fluid leads to a similar phenotype. Reduced blood-brain barrier permeability in the absence of {gamma}{delta} T cells results in decreased bacterial invasion and diminished microglia activation. Wild-type but not {gamma}{delta} T cell-deficient mice surviving infection exhibit increased hyperactivity and open space anxiety during early adulthood, a behavioural profile that may reflect attention deficit and hyperactivity (ADHD)-like tendencies. Altogether, these findings establish a pathogenic role for meningeal {gamma}{delta}17 T cells in early life, uncovering a key mechanism that drives long-term sequelae in GBS neonatal meningitis.

immunology↗

bioRxiv2025

Give It Time: Green Anacondas Show Prolonged Behavioral Responses to Enclosure Enhancements

Information about green anacondas (Eunectes murinus) in human care is limited, especially concerning their behavior, welfare, and overall well-being. To help bridge this knowledge gap, this study evaluated how exhibit design enhancements influence E. murinus behavior. The aim was to assess immediate behavioral changes following enclosure modifications and investigate potential habituation over time, ultimately evaluating the effectiveness and longevity of the behavioral changes induced by the improved environment. Systematic observations were divided into three phases: before enclosure improvements, immediately after these modifications, and three weeks later. Enclosure modifications focused on areas less frequented by the anacondas during Phase 1. Results revealed decreased inactivity in Phase 2 and more balanced space use in Phase 3, with anacondas occupying previously underutilized areas, including the terrariums vertical dimension. Interaction with exhibit enhancement items increased in the studys final phase, where a decrease in engagement would be anticipated due to habituation. These results suggested the anacondas required additional time to acclimate to the modifications, even though environmental factors may have contributed to these changes. This study highlights how enclosure enhancements may benefit green anacondas welfare while underlining the importance of providing sufficient acclimation time to accurately evaluate the animals complete behavioral response. Simple SummaryGreen anacondas (Eunectes murinus) remain largely understudied, particularly in terms of their behavior and welfare in human care. To address this knowledge gap, improvements were made to the enclosure of green anacondas in captivity, and their behaviors were observed before and after the modifications. The observations were divided into three phases: before the changes (Phase 1), immediately after (Phase 2), and approximately three weeks later (Phase 3). The modifications focused on areas that were rarely utilized during Phase 1. After the improvements, the anacondas became more active and used their enclosure more evenly, including at varying heights. The anacondas interacted more with the new enclosure features after the three weeks, when increased disinterest would have been expected, although environmental conditions may have influenced these changes. These findings show how enclosure modifications may help enhance the welfare of green anacondas and emphasize the need for research that allows enough time for the animals to fully adjust, ensuring a complete understanding of their response.

animal behavior and cognition↗

bioRxiv2025

Patient-derived organoids to study glycosylation dynamics during gastric disease

BACKGROUND AND AIMSAberrant cellular glycosylation remains a key event that accompanies and actively sustains gastric neoplastic transformation. Patient-derived organoids (PDOs) have recently emerged as a promising ex vivo model to study human gastric disorders. Since the PDOs glycosylation landscape remains unknown, this study aims to evaluate PDOs as potential avatars of in vivo tissue glycosylation profiles in the gastric context. METHODSFresh gastric mucosa samples derived from non-tumoral obese patients (n=11), adjacent tumor mucosa samples (n=29), and tumor tissue samples derived from gastric cancer (GC) patients (n=30) were used to establish a biobank of gastric PDOs (n=56). The N- and O-glycophenotypes of normal, adjacent, and tumor PDOs and respective in vivo tissues were thoroughly characterized by immunostaining. Additionally, a comparative glycan analysis was performed over time, upon PDO biobanking and xenografting in mice. The binding of two Helicobacter pylori (H. pylori) isogenic strains with distinct glycan-binding affinities was assessed in parental gastric mucosa tissues and compared with the respective PDOs before and after modulation of their glycan landscape. RESULTSOur results show that PDOs mimic different phenotypes of the carcinogenic cascade and recapitulate parental gastric tissues glycosylation profile. Tumor PDOs recapitulate the inter- and intra-heterogeneity features observed in GC, which is maintained over time, upon biobanking and xenografting. We demonstrated that the expression of type I and type II Lewis antigens is dynamically controlled by PDOs differentiation status, which results in differential binding to H. pylori strains displaying distinct glycan-binding adhesins, mirroring the gastric epithelium tissue interactions. CONCLUSIONSThis study established PDOs as invaluable ex vivo tools to study the complex glycan dynamics in both gastric physiological and pathological settings.

cell biology↗

bioRxiv2023

Prefrontal cortex proteomic alteration after social instability stress in adolescents rats

Early life stress can have significant effects on the developing brain and lead to changes in the structure and function of brain regions involved in stress regulation, emotion and cognitive control. Here, we used the social instability stress (SIS) protocol to understand the impact of social stress during mild (PND30) and late (PND45) adolescence. Our results revealed that SIS can compromise the dominance-subordination coping strategy but does not affect social recognition and motivation in rats. Moreover, SIS can lead to subtle modifications at the molecular level that hamper normal development of the prefrontal cortex in a sex- and age-dependent manner. Understanding the impact of early life stress on brain organization is crucial for developing effective prevention and intervention strategies. By identifying those who are most vulnerable to the effects of stress and providing targeted support and resources, it may be possible to mitigate the negative consequences of early adversity and promote healthy brain development.

neuroscience↗

bioRxiv2021

Microglia remodel the synaptic signaling required for context-dependent cognitive performance

Microglial homeostatic functions are fundamental to regulate the central nervous system microenvironment. We use conditional cell-specific gene targeting, RNA-seq profiling, high-throughput proteomics, phosphoproteomics, systems biology, and animal behavior to report a critical role for the RhoGTPase Rac1 in regulating adult microglia physiology. Ablation of Rac1 in adult microglia impaired their ability to sense and interpret the brain microenvironment and affected their capacity to communicate with synapses to drive cognitive performance, both at the steady-state and during experience-dependent plasticity. Overall, our results reveal a novel and central role for Rac1 as a regulator of microglia homeostasis and a molecular driver of the microglia-synapse crosstalk required for context-dependent sociability and learning related to memory.

neuroscience↗

bioRxiv2021

Altered environmental perception by parental stress and depression vulnerability: impact on mothers and offspring

Depressive mothers often find the mother-child interaction to be challenging. Parental stress may further impair mother-child attachment, which may increase the risk of negative developmental consequences. We used rats with different vulnerability to depression (Wistar and Kyoto) to investigate the impact of stress (maternal separation-MS) on maternal behaviour and adolescent offspring cognition. MS in Kyoto dams increased pup-contact, resulting in higher oxytocin levels and lower anxiety-like behaviour after weaning, while worsening their adolescent offspring cognitive behaviour. Whereas MS in Wistar dams elicited higher quality of pup-directed behaviour, increasing Brain-Derived Neurotrophic Factor (BDNF) in the offspring, which seems to have prevented a negative impact on cognition. Hypothalamic oxytocin seems to impact the salience of the social environment cues (as negative for Kyoto) leading to different coping strategies. Our findings highlight the importance of contextual and individual factors in the understanding of the oxytocin role in modulating maternal behaviour and stress regulatory processes.

neuroscience↗

bioRxiv2021

Astrocyte-derived TNF and glutamate critically modulate microglia reactivity by methamphetamine

Methamphetamine (Meth) is a powerful illicit psychostimulant, widely used for recreational purposes. Besides disrupting the monoaminergic system and promoting oxidative brain damage, Meth also causes neuroinflammation that contributes to synaptic dysfunction and behavioral deficits. Aberrant activation of microglia, the largest myeloid cell population in the brain, is a common feature in neurological disorders linked to cognitive impairment and neuroinflammation. In this study, we investigated the mechanisms underlying the aberrant activation of microglia elicited by Meth in the adult mouse brain. We found that binge Meth exposure caused microgliosis and disrupted risk assessment behavior (a feature that usually occurs in human Meth abusers), both of which required astrocyte-to-microglia crosstalk. Mechanistically, Meth triggered a detrimental increase of glutamate exocytosis from astrocytes (in a manner dependent on TNF production and calcium mobilization), promoting microglial expansion and reactivity. Ablating TNF production or suppressing astrocytic calcium mobilization prevented microglia reactivity and abolished the behavioral phenotype elicited by Meth exposure. Overall, our data indicate that glial crosstalk is critical to relay behavioral alterations caused by acute Meth exposure. One Sentence SummaryGlial crosstalk under methamphetamine exposure

neuroscience↗

bioRxiv2021

Cofilin pathology is a new player on α-synuclein-induced spine impairment in models of hippocampal synucleinopathy

Cognitive dysfunction and dementia are presently recognized as major complications in -synucleinopathies, namely in Dementia with Lewy Bodies (DLB) and Parkinsons disease with dementia (PDD). In these disorders, -Synuclein (Syn) accumulation affects severely the hippocampus by inducing synaptic dysfunction which culminates in cognitive impairment. To characterize the mechanisms underlying Syn-induced neuronal dysfunction we analysed the effect of overexpression or extracellular administration of Syn on hippocampal neurons. We observed that Syn induces the dysregulation of the actin-binding protein cofilin and its assembly into rod structures in a mechanism mediated by the cellular prion protein (PrPC). Moreover, we unraveled cofilin pathology as mediator of Syn-induced dendritic spine impairment in hippocampal neurons. Importantly, in a synucleinopathy mouse model with cognitive impairment we validated cofilin dysregulation and synaptic dysfunction at the same age when cognitive deficits were observed. Our data supports cofilin as a novel player on hippocampal synaptic dysfunction triggered by Syn on Lewy Body dementias.

neuroscience↗

bioRxiv2020

Genome-Wide Identification of Epigenetic Regulators in Quercus suber

Modifications of DNA and histones, including methylation and acetylation, are critical for the epigenetic regulation of gene expression during plant development, particularly during environmental adaptation processes. However, information on the enzymes catalyzing all these modifications in perennial trees, such as Quercus suber, is still not available. In this study, several epigenetic modifier proteins, including eight DNA methyltransferases (DNA Mtases), three DNA demethylases (DDMEs) and ninety-one histone modifiers including thirty-five histone methyltransferases (HMTs), twenty-six histone demethylases (HDMTs), eight histone acetyltransferases (HATs) and twenty-two histone acetylases (HDACs) were identified in Q. suber. Phylogenetic analyses of the DNA and histone modifier proteins were performed using several plant species homologs, enabling the classification of the Q. suber proteins. Additional in silico analysis showed that some Q. suber DNA Mtases, DMEs and histone modifiers have the typical domains found in the plant model Arabidopsis, which might suggest a conserved functional role. A link between the expression levels of each gene in different Q. suber tissues (buds, flowers, acorns, embryos, cork and roots) with the functions already known for their closest homologs in other species was also established. Therefore, the data generated here are important for future studies exploring the role of epigenetic regulators in this economically important species.

genomics↗

bioRxiv2019

An integrated genomic approach to dissect the genetic landscape regulating the cell-to-cell transfer of a-synuclein

Neuropathological and experimental evidence suggests that the cell-to-cell transfer of a-synuclein has an important role in the pathogenesis of Parkinsons disease (PD). However, the mechanism underlying this phenomenon is not fully understood. We undertook an siRNA, genome-wide high throughput screen to identify genes regulating the cell-to-cell transfer of a-synuclein. We transiently transfected HEK cells stably overexpressing a-synuclein with a construct encoding GFP-2a-aSynuclein-RFP. The cells expressing a-synuclein-RFP through transfection were double positive for GFP and RFP fluorescence, whereas the cells receiving it through transfer were positive only for RFP fluorescence. The amount of a-synuclein transfer was quantified by high content microscopy. A series of unbiased screens confirmed the involvement of 38 genes in the regulation of a-synuclein-RFP transfer. One of those hits was ITGA8, a candidate gene recently identified through a large PD genome wide association study (GWAS). Weighted gene co-expression network analysis (WGCNA) and weighted protein-protein network interaction analysis (WPPNIA) showed that the hits clustered in networks that included known PD Mendelian and GWAS risk genes more frequently than expected than random chance. Given the genetic overlap between a-synuclein transfer and PD, those findings provide supporting evidence for the importance of the cell-to-cell transfer of a-synuclein in the pathogenesis of PD, and expand our understanding of the mechanism of a-synuclein spread.

neuroscience↗

bioRxiv2017

Genetic ablation of RhoA in adult microglia causes synapse and neuronal loss

Nervous tissue homeostasis requires regulation of microglia activity. Using conditional gene targeting in mice, we demonstrate that genetic ablation of the small GTPase Rhoa in adult microglia is sufficient to trigger spontaneous microglia activation producing a neurological phenotype (including synapse and neuron loss, impairment of LTP, formation of {beta}-amyloid plaques and memory deficits). Mechanistically, loss of Rhoa in microglia triggers Src activation and Src-mediated Tnf production, leading to excitotoxic glutamate secretion. Inhibiting Src in microglia Rhoa-deficient mice attenuates microglia dysregulation and the ensuing neurological phenotype. We also found that the Rhoa/Src signaling pathway was disrupted in microglia of the APP/PS1 mouse model of Alzheimers disease and that low doses of A{beta} oligomers triggered microglia neurotoxic polarization through the disruption of Rhoa-to-Src signaling. Overall, our results indicate that disturbing RhoGTPase signaling in microglia can directly cause neurodegeneration.

neuroscience↗