Biology subjects

Portugal, C. C.

Publications and source records attributed to Portugal, C. C..

6 recordsLinked to original sources

bioRxiv2024

Increasing the vitamin C transporter SVCT2 in microglia improves synaptic plasticity and restrains memory impairments in Alzheimer's disease models

Alzheimers Disease (AD) is characterized by progressive cognitive decline and synaptic dysfunction, often associated with amyloid-beta accumulation and microglial alterations. Here, we investigate the role of the Sodium-dependent Vitamin C Transporter 2 (SVCT2) in microglia to modulate AD-like pathology in mice. Using a combination of RNA sequencing, advanced quantitative proteomics, electrophysiology, behavioral tests, high-throughput imaging, and microglial viral gene delivery, we explore the interplay between SVCT2 expression in microglia, amyloid-beta load, synaptic proteome changes, and synaptic plasticity. Our results demonstrate that SVCT2 expression in microglia decreases with age in the 5xFAD mice, correlating with memory deficits and alterations in synaptic mitochondrial proteome. Importantly, overexpression of SVCT2 in microglia leads to enhanced clearance of amyloid plaques and reconfiguration of the mitochondrial proteome landscape in the synapses, improving synaptic long-term plasticity (LTP) and memory performance. Our findings underscore the SVCT2 overexpression in microglia as a potent strategy to simultaneously decrease amyloid pathology and enhance synaptic plasticity and memory performance, offering new avenues for therapeutic interventions in AD.

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↗

bioRxiv2019

Alcohol intake triggers aberrant synaptic pruning leading to synapse loss and anxiety-like behavior

Alcohol use adversely impacts the life of millions of people worldwide. Deficits in synaptic transmission and in microglial function are common findings in human alcohol users and in animal models of alcohol intoxication. Here, we show that alcohol intake over ten consecutive days resulted in substantial loss of excitatory synapse in the prefrontal cortex, a consequence of aberrant synaptic pruning, which led to increased anxiety-like behavior. Mechanistically, these effects of alcohol intake were mediated by a detrimental increase of microglia engulfment capacity via Src-dependent activation of NFkB and consequent TNF production. Accordingly, pharmacological blockade of Src activation or TNF production by microglia, genetic ablation of TNF, or diphtheria toxin-mediated conditional ablation of microglia attenuated aberrant synaptic pruning preventing excitatory synapse loss and anxiety-like behavior. Overall, our data suggest that aberrant pruning of excitatory synapses by microglia might disrupt synaptic transmission during alcohol use.

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↗