Biology subjects

Maldonado, R.

Publications and source records attributed to Maldonado, R..

At least 19 recordsLinked to original sources

bioRxiv2026

Streptomyces sp. N2A promotes tomato (Solanum lycopersicum L.) vegetative growth and yield by modifying fruit morphology

Tomato production, yield and fruit quality face major challenges due to several factors, including the complex polygenic inheritance of agronomically relevant traits, biotic and abiotic stresses, and increasingly stringent regulations limiting the use of phytosanitary products. In this context, bioinoculants have emerged as a sustainable strategy capable of enhancing yield without compromising fruit quality, conferring protection against different stresses and exerting a minimal or no impact on environment and human health. In this study, we evaluated the effects and the underlying mechanisms by which Streptomyces sp. N2A, an actinobacteria isolated from soybean rhizosphere, promotes seed germination, vegetative growth and yield in tomato, without modifying fruit quality. The obtained results demonstrated that the bacterial treatment significantly improved seedlin[g]s emergence and growth and development in vegetative stage. At harvest, yield was also significantly enhanced, mainly driven by increased individual fruit weight, which was positively correlated with a thicker pericarp in fruits from N2A-treated plants. Transcriptional analysis during fruit development revealed a coordinated induction of auxin and cytokinin signaling pathways before and after anthesis, providing a hormonal framework that underlies the promotion of pericarp growth. This study provides evidence of the beneficial effect of inoculation with Streptomyces sp. N2A on tomato yield and constitutes the first report describing the modification of fruit morphology and expression of genes involved in phytohormonal modulation during early growth and development, induced by a plant growth-promoting Streptomyces.

plant biology↗

bioRxiv2026

Distinct Glutamatergic Inputs to the Nucleus Accumbens Differentially Regulate Vulnerability to Cannabinoid Addiction

Cannabis use disorder (CUD) is a chronic relapsing disorder characterized by compulsive drug seeking, persistent drug use despite adverse consequences, and a high risk of relapse. Although the nucleus accumbens (NAc) is a central hub in the neural circuitry underlying addiction, the specific glutamatergic inputs regulating vulnerability to cannabinoid addiction remain poorly understood. Here, we investigated the contribution of two major limbic glutamatergic projections to the NAc, the dorsal hippocampus (dHPC) to NAc and basolateral amygdala (BLA) to NAc pathways, using a validated mouse model of WIN55,212-2 intravenous self-administration combined with projection-specific chemogenetic inhibition. Male C57BL/6J mice received combinatorial viral vector delivery of inhibitory hM4Di DREADDs selectively targeting either the dHPC to NAc or the BLA to NAc pathway. Chronic pathway inhibition was achieved by continuous administration of deschloroclozapine through osmotic minipumps during the development of cannabinoid addiction-like behavior. Animals were evaluated using a multidimensional behavioral paradigm assessing the three-core addiction-like criteria of persistence of drug seeking, motivation, and compulsive-like behavior, as well as craving-related behaviors and phenotypic vulnerability traits. Chronic inhibition of either the dHPC to NAc or the BLA to NAc pathway significantly increased the proportion of mice developing an addiction-like phenotype. Both manipulations enhanced persistence of drug seeking during periods of drug unavailability, identifying persistence as a shared behavioral consequence of disrupting glutamatergic signaling to the NAc. In contrast, the two pathways differentially regulated other addiction-related behaviors. Inhibition of the dHPC to NAc pathway increased motivation to obtain WIN55,212-2, impulsivity, reward sensitivity, and resistance to extinction, whereas inhibition of the BLA to NAc pathway selectively enhanced cue-induced drug seeking. Neither manipulation altered compulsive-like responding, locomotor activity, or body weight. These findings demonstrate that distinct glutamatergic afferents to the NAc differentially regulate vulnerability to cannabinoid addiction-like behavior while converging on persistence as a common circuit-level mechanism. Our results establish the NAc as an integrative hub coordinating complementary contextual and emotional information during the transition to cannabinoid addiction and provide a circuit-based framework for understanding the neural mechanisms underlying Cannabis Use Disorder.

neuroscience↗

bioRxiv2026

Sex-specific vulnerability to cannabinoid addiction-like behavior and associated miRNA signatures in a WIN 55,212-2 self-administration mouse model

Cannabis is one of the most widely used psychoactive substances worldwide, and cannabis use disorder (CUD) is increasingly recognized as a major public health concern. Clinical evidence indicates that women may be particularly vulnerable to developing addiction, exhibiting a faster transition from initial drug use to loss of control and increased relapse vulnerability. However, females remain underrepresented in both preclinical and clinical research, limiting our understanding of the neurobiological mechanisms underlying this susceptibility. Here, we investigated sex differences in behavioral and epigenetic susceptibility to cannabinoid addiction using a mouse operant self-administration model with the synthetic cannabinoid agonist WIN 55,212-2. Female mice displayed increased addiction-like behavior, characterized by greater persistence of responding during drug-free periods and enhanced compulsive-like drug seeking compared to males. miRNA profiling in the medial prefrontal cortex (mPFC) identified a female-specific epigenetic signature associated with the addiction-like phenotype, including downregulation of mmu-miR-669j, mmu-miR-7036b-5p, mmu-miR-878-3p, and mmu-miR-7017-3p, together with upregulation of mmu-miR-3092-5p in addicted females. Functional enrichment analyses of predicted target genes revealed pathways related to synaptic organization, axon guidance, neurotransmission, and structural plasticity. Together, these findings demonstrate sex-dependent differences in vulnerability to cannabinoid addiction-like behavior and identify a specific miRNA signature in the mPFC associated with this phenotype, highlighting potential targets for the development of sex-specific therapeutic strategies.

neuroscience↗

bioRxiv2026

β-Hydroxybutyrate elicits divergent metabolic responses between MCF-7 and T47D ER+ breast cancer cells under glucose restriction

BackgroundThe ketogenic diet is being explored as an adjuvant intervention in breast cancer because it lowers circulating glucose and elevates ketone bodies such as {beta}-hydroxybutyrate (BHB), but how individual ER+ breast cancer subtypes adapt to these conditions remains poorly characterized. We examined metabolic responses to BHB supplementation under glucose restriction in two ER+ breast cancer cell lines, asking whether metabolic adaptation patterns differ between models. MethodsMCF-7 and T47D cells were cultured under high glucose, glucose-restricted (5% of standard), or glucose-restricted with 10 mM BHB conditions and profiled by comprehensive two-dimensional gas chromatography-mass spectrometry (GCxGC-MS). Pairwise Welchs t-tests with Benjamini-Hochberg false discovery rate (FDR) correction were applied to identify treatment-responsive metabolites. Targeted assays quantified intracellular glycine, SHMT1 protein, and total branched-chain amino acid (BCAA) concentrations across a BHB dose range (2.5-15 mM). Patient tumor transcriptomic data from TCGA (n=1,084) and paired tumor-normal samples from GSE58135 (n=20) were analyzed for genes involved in one-carbon, ketone body, and BCAA metabolism. ResultsMCF-7 and T47D cells exhibited markedly divergent metabolic responses to BHB. In MCF-7 cells, BHB supplementation produced a broad pattern-level metabolic shift: 75% of detected metabolites trended upward when BHB was added to glucose-restricted cultures (C vs. B comparison), with 1,4-butanediol reaching nominal significance (FC=2.35, p=0.016) and a 4.1-fold trend increase in lactic acid (p=0.11), although no individual metabolite survived FDR correction. T47D cells showed essentially no metabolic response to BHB at the global level. Targeted assays detected an elevation in glycine at 5 mM BHB in both cell lines that did not follow a monotonic dose response and was not accompanied by changes in SHMT1 protein expression. Total BCAA levels were elevated by BHB in T47D cells but remained unchanged in MCF-7 cells. In paired patient samples, OXCT1 (log2FC = -1.41), SHMT1 (log2FC = -1.31), and ACAT1 (log2FC = -1.07) were significantly downregulated in ER+ tumors relative to matched normal tissue (adjusted p < 0.001 for all three). ConclusionsER+ breast cancer cell lines show heterogeneous metabolic responses to BHB supplementation under glucose restriction. The broad pattern of metabolite elevation in MCF-7 but not T47D cells suggests that capacity to utilize ketone bodies as metabolic substrate varies between ER+ models. The downregulation of OXCT1, ACAT1, and SHMT1 in ER+ tumors compared to normal tissue identifies these enzymes as candidate biomarkers that may help stratify which patients are likely to benefit from ketogenic interventions. Findings related to individual metabolites should be regarded as exploratory and require validation in larger, adequately powered cohorts.

cancer biology↗

bioRxiv2026

Selective Shank3 Deletion in Glutamatergic Neurons of the Anterior Insular Cortex Induces Autism-Related Behavior and Circuit Dysfunction

Mutations in the synaptic scaffold protein SHANK3 represent one of the most frequent genetic causes of autism spectrum disorder (ASD), yet the circuit mechanisms through which SHANK3 dysfunction leads to behavioral alterations remain incompletely understood. The anterior insular cortex (aINS) is a key integrative hub involved in socio-emotional processing, anxiety regulation, and social cognition, a group of behaviors frequently disrupted in ASD. Here, we investigated whether selective deletion of SHANK3 signaling in glutamatergic neurons of the aINS is sufficient to produce ASD-relevant behavioral and circuit phenotypes. Using conditional Shank3flox4-22 mice combined with stereotaxic viral delivery of Cre recombinase under the CaMKII promoter, we selectively deleted Shank3 in glutamatergic neurons of the aINS. Behavioral phenotyping revealed increased anxiety-like behavior, enhanced repetitive behavior, and impaired social memory, while sociability and locomotor activity were largely preserved. These behavioral alterations were accompanied by genotype-dependent differences in neuronal activity revealed by calcium imaging, indicating disrupted activity dynamics in insular glutamatergic neurons following Shank3 deletion. To assess the broader relevance of these findings, we evaluated the behavioral profile of BTBR T+ Itpr3tf/J mice, a model of idiopathic ASD, in the same battery of behavioral tests. Several behavioral alterations observed following insular Shank3 deletion partially overlapped with those present in BTBR mice, supporting the relevance of aINS Shank3 in ASD-related phenotypes. Together, these findings identify glutamatergic neurons of the aINS as a critical locus through which Shank3 dysfunction can disrupt socio-emotional, cognitive, and repetitive behaviors. Our results highlight the aINS as a key circuit node contributing to ASD-related behavioral alterations and provide mechanistic insight into how synaptic scaffold disruption leads to circuit dysfunction and produces behavioral alterations.

neuroscience↗

bioRxiv2026

Anterior insular CB1 receptor signaling selectively regulates social novelty and anxiety-related behaviors

Several neurodevelopmental disorders (NDDs) are characterized by impairments in social behavior and affective dysregulation. Converging evidence implicates the endocannabinoid system in the control of both behaviors. However, the brain region-specific contribution of cannabinoid receptor type 1 (CB1R) signaling to these NDD-relevant phenotypes remains unclear. The anterior insular cortex (aINS) is a key integrative hub involved in socio-emotional processing and social novelty recognition. Whether CB1Rs within this region are sufficient to regulate behavioral domains disrupted in NDDs remains unclear. Here, we employed a Cre-dependent viral strategy to selectively restore CB1R mRNA expression in the aINS of global CB1R-deficient mice. Region-specific rescue of CB1R in the aINS normalized social novelty discrimination and reduced anxiety-like behavior as compared to mice lacking CB1R, while leaving basal sociability and locomotor activity unaffected. In addition, insular CB1R re-expression modulated repetitive-like behaviors without broadly altering other behavioral domains. These effects were observed in the absence of off-target expression, supporting the specificity of the genetic manipulation. Our findings demonstrate that CB1R mRNA expression within the aINS is sufficient to regulate distinct socio-emotional and repetitive behavioral domains. These results identify the aINS as a critical CB1-dependent modulatory node and provide mechanistic insight into how region-specific endocannabinoid signaling contributes to behavioral phenotypes relevant to NDDs.

neuroscience↗

bioRxiv2026

RNA-DNA triplex-forming miRNAs define an evolutionarily recent chromatin regulatory mechanism

MicroRNAs (miRNAs) are best known for their role in post-transcriptional gene regulation in the cytoplasm. However, a subset of miRNAs has been detected in the nucleus, suggesting additional regulatory functions. Here, we systematically characterize chromatin-associated small non-coding RNAs in the human pancreatic cancer cell line PANC-1. Using chromatin RNA immunoprecipitation coupled with small RNA sequencing, we show that the chromatin-associated small RNA population differs markedly from the bulk nuclear RNA pool and is strongly enriched in miRNAs. Among these, miR-21 represents the most abundant chromatin-associated species. Sequence analyses revealed that a subset of these miRNAs fulfills the requirements for RNA-DNA triplex formation at genomic regulatory regions. Gel-shift assays further demonstrate that Argonaute2 (Ago2) directly interacts with triple-helical nucleic acid structures in vitro, suggesting a potential mechanistic link between triplexes and Ago2-chromatin engagement. Evolutionary analyses indicate that these triplex-forming chromatin-associated miRNAs are largely restricted to anthropoid primates, in contrast to broadly conserved non-triplex-forming miRNAs. Together, our results identify a population of chromatin-associated miRNAs and provide evidence for a potential structural mechanism linking miRNAs, Ago2, and chromatin.

molecular biology↗

bioRxiv2026

Evolutionary history and functional divergence of hydroxycarboxylic acid receptors in primates

Hydroxycarboxylic acid receptors (HCARs) are class A G-protein-coupled receptors that function as metabolic sensors. This receptor family includes three members (HCAR1, HCAR2, and HCAR3) expressed in metabolically active tissues and immune cells, where they link cellular metabolic status to physiological responses. This study aims to elucidate the evolutionary history of the most recently originated members of the HCAR gene family, namely HCAR2 and HCAR3, in primates. According to our phylogenetic analyses, the duplicative history of these genes involved multiple independent duplication events during ape evolution. Thus, most ape lineages possess independently originated duplicated copies, while non-ape primates retain the ancestral condition of a single-copy gene (HCAR2/3). Our analyses further indicate that this single-copy gene in non-ape primates is functionally equivalent to HCAR2, suggesting that the primary functional innovation in apes is associated with the physiological roles of HCAR3. Finally, gene expression analyses reveal that major divergence in tissue expression occurred after the initial duplication event that generated HCAR1 and the HCAR2/3 lineage, whereas HCAR2 and HCAR3 exhibit substantial overlap in their expression profiles. Thus, the more refined and context-dependent regulation of lipid metabolism that provides the HCAR3 receptor seems to have originated multiple times during the evolutionary history of apes.

evolutionary biology↗

bioRxiv2026

2-AG as a potential biomarker for predicting response to short-term fluoxetine treatment in a mouse model of depression

Major depressive disorder (MDD) is a complex psychiatric condition with significant individual and social impact and marked variability in treatment response. Identifying biomarkers that predict antidepressant efficacy remains a major challenge, and metabolomic approaches offer a powerful tool to uncover biochemical changes associated with depression and treatment outcome. The prefrontal cortex and the hippocampus are key brain regions involved in the pathophysiology of MDD and antidepressant response. Fluoxetine, one of the most commonly prescribed antidepressants, influences not only serotonergic signaling but also the endocannabinoid system. Accordingly, evaluating endocannabinoid levels in these brain regions might provide critical insight into their contribution to mood disorders and the effect of fluoxetine. To identify biomarkers associated with early antidepressant response, male mice were exposed for 5 weeks to the unpredictable chronic mild stress (UCMS) protocol, with fluoxetine treatment administered during the final week. Liquid chromatography-tandem mass spectrometry analyses of hippocampal and prefrontal cortex samples revealed that the depression-like phenotype induced by UCMS was associated with increased hippocampal anandamide (AEA) levels. Behavioral improvement following short-term fluoxetine treatment was accompanied by enhanced hippocampal 2-arachidonoylglycerol (2-AG), which was associated with reduced GABA and glutamate levels in the prefrontal cortex. These findings suggest that increased 2-AG levels may serve as a predictor of early response to fluoxetine.

neuroscience↗

bioRxiv2025

Involvement of the medial prefrontal cortex in food addiction: new insights from in vivo calcium Imaging

Food addiction is a multifactorial disorder characterized by a loss of control over food intake, contributing to the development of obesity. To investigate the involvement of the prelimbic (PL) medial prefrontal cortex (mPFC) in the transition to food addiction, we examined PL calcium dynamics in mice exhibiting addicted versus non-addicted behavioral phenotypes. Our behavioral results allowed the identification of two distinct subpopulations of addicted and non-addicted mice, enabling direct comparison of their neural activity profiles. Addicted and non-addicted mice showed significant differences across several PL calcium activity parameters. These findings demonstrate a strong association between PL mPFC calcium activity dynamics and key addiction criteria, highlighting a critical role of this brain region in the development of food addiction. Understanding these neurobiological differences enhances our insight into brain mechanisms underlying loss of eating control and may inform more targeted approaches for studying and ultimately treating food addiction.

neuroscience↗

bioRxiv2025

CB1 receptor inhibition in fragile X syndrome mice impacts alternative splicing alterations in hippocampal synaptoneurosomal transcriptome

BackgroundFragile X syndrome (FXS) conveys the most frequent heritable genetic cause of intellectual disability and autism. It is caused by a CGG repeat expansion in FMR1 gene that leads to the loss of fragile X messenger ribonucleoprotein 1 (FMRP). FMRP is highly abundant in synapses, where regulates mRNAs to maintain synaptic plasticity. Treatments under development significantly ameliorate neurological and behavioral landmarks in the mouse model of the disorder, the Fmr1 knockout (FX) mouse. Specifically, previous studies revealed that pharmacological and genetic inhibition of cannabinoid type-1 receptor (CB1R) restored phenotypic traits in FX mice. However, the molecular hallmarks associated with this experimental therapeutic intervention are largely unknown. MethodsFirst, we aimed to evaluate the validity of synaptoneurosomes preparations to investigate specific mRNA modifications at synapses. Afterwards, combining in silico high-throughput analysis and biochemical determinations, we analyzed the hippocampal synaptoneurosomal transcriptome after pharmacological inhibition of CB1R with the specific antagonist/inverse agonist rimonabant in FX male mice ResultsWe verified that synaptoneurosomes provide an accurate representation of synaptic composition and function. Then, we found that rimonabant treatment had a limited impact at gene expression level but produced significant modifications in transcript expression. Indeed, detailed analysis of alternative splicing events revealed a relevant number of events in which splicing was reverted from the FX form to the WT form by the treatment. LimitationsWe demonstrated that rimonabant treatment alters the AS landscape in FX hippocampal synaptoneurosomes; however, further studies are needed to elucidate if other neural components also contribute to the modifications and whether the findings are specific to rimonabant treatment or to CB1R inhibition at synapses. In addition, additional research could be required to clarify whether the changes in AS events could be affected by interindividual variability or technical protocols. ConclusionsWe determined that the AS landscape is modified in FX hippocampal synaptoneurosomes and that these changes are sensitive to rimonabant treatment which could explain the beneficial effects of this experimental therapeutic approach in FXS. Altogether, our results reveal a new level of complexity in the effect of pharmacological treatment to improve symptoms in the context of FXS.

neuroscience↗

bioRxiv2025

A serotonergic mechanism is involved in the pro-cognitive effect of AM6545 treatment in a mouse model of fragile X syndrome

Fragile X syndrome (FXS) is the principal monogenic syndrome leading to inherited intellectual disability and autism. It is caused by the silencing of FMR1 gene that leads to the loss in the expression of its encoded protein, the fragile X messenger ribonucleoprotein 1 (FMRP). In synapses, FMRP has a key role in local mRNA modulation to maintain synaptic plasticity. The Fmr1 KO (FX) mouse model shows cognitive impairment and some of the synaptic traits present in individuals with FXS together with alterations in gut microbiota. Previous studies revealed that pharmacological and genetic cannabinoid type-1 receptor (CB1R) inhibition significantly prevented central key alterations in FX mice. Here, we aimed to evaluate the effect of a sub-chronic treatment with the largely peripherally-restricted CB1R antagonist AM6545. We found that AM6545 reduced memory deficits and restored enhanced hippocampal mGluR5-dependent long-term depression and aberrant dendritic spine density in FX mice. At the peripheral level, AM6545 modified altered FX mice fecal microbiota composition, while in the hippocampus AM6545 treatment upregulated hippocampal Htr4, the gene encoding for serotonin receptor 4 (5-HT4R) This upregulation positively correlated with memory performance. Notably, acute pharmacological blockade of 5-HT4R abolished the pro-cognitive effect produced by AM6545. Together, our results suggest that peripheral CB1R inhibition ameliorates key alterations in FX mouse model and modifies the expression of serotonergic receptors important for cognitive performance.

animal behavior and cognition↗

bioRxiv2025

An Evolutionary Novelty in TRPV1 Functional Regulation: Characterization of a Dominant-Negative Isoform Exclusive to Catarrhine Primates

TRPV1, a member of the transient receptor potential (TRP) family, is a non-selective cation channel primarily known for its role in pain perception, inflammation, and thermosensation. In mammals, it responds to noxious heat (>43{degrees}C) and chemical stimuli such as capsaicin and protons. It is widely expressed in sensory neurons, notably in the dorsal root and trigeminal ganglia. However, it is also found in some non-neuronal tissues, like the skin and bladder. The human canonical variant of TRPV1 renders a protein with 839 residues. Different splice variants have been described, and some display a dominant negative effect, partially or totally inhibiting the activity of the canonical counterpart. Here, we characterize a splice variant that encodes for a channel of 850 amino acids (TRPV1850). This variant is an evolutionary novelty of catarrhine (Old World monkeys and apes) primates, incorporating an exon of 33 bp long. Both imaging of membrane expression and electrophysiological recordings suggest that TRPV1850 alone does not reach the plasma membrane. However, in cells co-expressing the canonical and TRPV1850 variants, the latter would act as a dominant negative, preventing the canonical variant from reaching the plasma membrane and rendering smaller macroscopic currents in response to capsaicin. Thus, this new isoform of the TRPV1 ion channel represents a novel form of functional regulation only present in apes and Old World monkeys. SignificanceWe identified a novel isoform of the TRPV1 ion channel, a protein essential for detecting pain and heat stimuli unique to apes and Old World monkeys. This isoform contains an additional exonic sequence encoding eleven amino acids, which originated in the common ancestor of apes and Old World monkeys. This additional exonic sequence disrupts a specific domain in the N-terminal region of the protein, resulting in functional differences. Unlike the canonical TRPV1 isoform, this variant cannot reach the plasma membrane independently. Instead, it exerts a dominant-negative effect by interfering with the canonical TRPV1 protein, reducing its ability to localize to the cell surface and diminishing its responsiveness to capsaicin, a well-known TRPV1 activator.

evolutionary biology↗

bioRxiv2023

Sub-chronic peripheral CB1R inhibition enhances cognitive performance and induces hippocampal synaptic plasticity changes in naive mice

Background and PurposeThe peripheral contribution to brain function and cognitive performance is far from understood. Cannabinoid type-1 receptor (CB1R) is classically pictured in the central nervous system to have such a role. We previously demonstrated a novel mechanism where the acute peripheral CB1R inhibition in mice prolongs memory persistence. Here, we take advance of the repeated exposure to the peripherally-restricted CB1R antagonist to further reveal cognitive improvements and the hippocampal mechanisms involved. Experimental ApproachWe evaluated in young adult male and female mice the behavioural consequences of a sub-chronic treatment with AM6545. Moreover, an unbiased transcriptomic analysis, as well as electrophysiological and biochemical studies, were performed in the hippocampus of treated mice to elucidate the central cellular and molecular consequences of such peripheral approach. Key ResultsSub-chronic inhibition of peripheral CB1R with AM6545 resulted in enhanced memory in low and high arousal conditions. Moreover, executive function was facilitated after repeated AM6545 administration, further strengthening the cognitive improving properties of peripheral CB1R inhibition. Transcriptional analysis of hippocampal synaptoneurosomes from treated male and female mice revealed a sex-dependent modulation of synaptic transcripts by AM6545. Notably, AM6545 occluded long-term potentiation in CA3-CA1 synapses while enhancing input-output relation. This was accompanied by an increase in the hippocampal expression of Bdnf and Ngf. Conclusion and ImplicationsOur results show that peripheral CB1R inhibition contributes to the modulation of memory persistence, executive function, and hippocampal synaptic plasticity in mice, further indicating that peripheral CB1R could act as a target for a novel class of nootropic compounds. What is already known?- Acute peripheral CB1R inhibition enhances object-recognition memory persistence in mice. - Such enhancement occurs through a noradrenergic mechanism involving the vagus nerve. What does this study add?- Peripheral CB1R inhibition modifies synaptoneurosomal transcriptome in the hippocampus of mice. - No tolerance and no side effects were observed after peripheral CB1R inhibition. What is the clinical significance?- Peripheral CB1R inhibition may function as a novel strategy for cognitive improvement.

neuroscience↗

bioRxiv2023

The long non-coding RNA MALAT1 modulates NR4A1 expression through a downstream regulatory element in specific cancer-cell-types

Chromatin-associated long non-coding RNAs (lncRNAs) have been shown to define chromatin density, regulate gene expression, and are involved in the initiation and progression of various cancer types. Despite the wealth of studies describing transcriptome changes upon lncRNA modulation, little data is showing the direct effects of lncRNA on regulatory elements (REs) that drive gene expression. Here we explored the molecular mechanism of the chromatin-interacting lncRNA, MALAT1, through RNA- and ATAC-seq, using HeLa cells as a model system. Time-resolved MALAT1 knock-down assays revealed its direct regulation of a limited number of protein-coding genes. Loss of MALAT1 resulted in a substantial loss of chromatin accessibility downstream of the NR4A1 gene, associated with its down-regulation. CRISPR-i assays revealed that this region corresponds to a new downstream RE. Next, using TCGA data, we identified a direct correlation between the expression of NR4A1 and the accessibility of the downstream RE in breast cancer. The molecular mechanism was validated on estrogen receptor (ER) positive breast cancer cells (MCF7) and Pancreatic Duct Epithelioid Carcinoma (PANC1) cells, not showing this effect according to TCGA data. Indeed, MALAT1 regulates the expression of NR4A1 in a cell type-specific manner by changing the accessibility of the downstream RE. MALAT1 exhibits a molecular mechanism that fine-tunes the expression of cancer drivers, like NR4A1, in ER-positive breast cancer cells, but not in other cell types.

cell biology↗

bioRxiv2022

Prefrontal accumbens neural dynamics abnormalities in mice vulnerable to develop food addiction

Food addiction is characterized by a loss of behavioral control over food intake and is closely associated with several eating disorders, including obesity and binge eating. Despite its high prevalence, the underlying neural mechanisms of food addiction are still unresolved. We trained mice in an operant paradigm for 110 days to promote the development of food addiction. Then, we classified mice as addicted and extreme non-addicted based on three addiction criteria and recorded neural activities in the prelimbic medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) core through electrophysiology in vivo. Addicted mice presented disrupted mPFC-to-NAc signaling at high frequencies (hfo 150-200 Hz) during decision-making to obtain food. Moreover, addicted mice exhibited reduced low gamma oscillations and theta-gamma coupling in the NAc during reward expectancy. Disrupted mPFC-to-NAc connectivity and gamma synchrony in the NAc correlated with increased reinforcement levels, unraveling the functional relevance of these alterations. The cannabinoid type-1 (CB1) receptor antagonist rimonabant rescued neural alterations observed in the addicted mice.Reinforcement levels were reduced after rimonabant administration and the directionality of signals and oscillatory activity in the NAc were reversed in addicted mice during decision-making and reward expectation, respectively. These findings suggest that disrupted mPFC-NAc neural dynamics are candidate mechanisms underlying specific behavioral alterations associated with food addiction. The elucidation of these novel communication mechanisms between the mPFC and the NAc will provide advances towards future development of new therapeutic interventions for food addiction and related disorders.

animal behavior and cognition↗

bioRxiv2021

Long-term decreased cannabinoid type-1 receptor activity restores specific neurological phenotypes in the Ts65Dn mouse model of Down syndrome

Intellectual disability is the most prevalent and limiting hallmark of Down syndrome (DS), without any pharmacological treatment available. Neurodegeneration and neuroinflammation are relevant neurological features of DS reaching to early development of Alzheimers disease. Preclinical evidence suggests that the endocannabinoid system, an important neuromodulator on cognition and neuroinflammation, could act as beneficial target in DS. Indeed, cannabinoid type-1 receptor (CB1R) activity was enhanced in the hippocampus of young-adult trisomic Ts65Dn mice, a well-characterized surrogate model of DS. In previous studies, inhibition of CB1R, was able to restore key neurological deficits in this mouse model. To determine the possible clinical relevance of this target, it is mandatory to evaluate the long-term consequences of attenuated CB1R activity and to minimize the possible side-effects associated to this mechanism. We found that CB1R expression was significantly enhanced in the hippocampus brains of aged DS subjects. Similarly, middle-aged trisomic mice showed enhanced CB1R expression. Long-term oral administration of a low dose of the CB1R specific antagonist rimonabant was administered to male and female Ts65Dn trisomic and wild-type mice from the time of weaning to 10 months, an age when signs of neurodegeneration have been described in the model. CB1R inhibition resulted in significant cognitive improvement in novel object-recognition memory in trisomic male and female mice, reaching a similar performance to that of wild-type littermates. Interestingly, this long-term rimonabant treatment modify locomotor activity, anxiety-like behavior, body weight or survival rates. Brain analysis at 10 months of age revealed noradrenergic and cholinergic neurodegeneration signs in trisomic mice that were not modified by the treatment, although the alterations in hippocampal microglia morphology shown by vehicle-treated trisomic mice was normalized in trisomic mice exposed to rimonabant. Altogether, our results demonstrate a sustained pro-cognitive effect of CB1R inhibition at doses that do not produce major side effects that could be associated to an anti-inflammatory action, suggesting a potential interest in this target of to preserve cognitive functionality in DS.

neuroscience↗

bioRxiv2021

Auricular transcutaneous vagus nerve stimulation acutely modulates brain connectivity in mice

BackgroundBrain electrical stimulation techniques take advantage of the intrinsic plasticity of the nervous system, opening a wide range of therapeutic applications. Vagus nerve stimulation (VNS) is an approved adjuvant for drug-resistant epilepsy and depression. Its non-invasive form, auricular transcutaneous VNS (atVNS), is under investigation for applications, including cognitive improvement. ObjectiveWe aimed to study the effects of atVNS on brain connectivity, under conditions that improved memory persistence in CD-1 male mice. MethodsAcute atVNS in the cymba conchae of the left ear was performed using a standard stimulation protocol under light isoflurane anesthesia, immediately or 3 h after the training/familiarization phase of the novel object-recognition memory test (NORT). Another cohort of mice was used for bilateral c-Fos analysis after atVNS administration. Spearman correlation of c-Fos density between each pair of the thirty brain regions analyzed allowed obtaining the network of significant functional connections in stimulated and non-stimulated control brains. ResultsNORT performance was enhanced when atVNS was delivered just after, but not 3 h after, the familiarization phase of the task. No alterations in c-Fos density were associated to electrostimulation, but a significant effect of atVNS was observed on c-Fos-based functional connectivity. atVNS induced a clear reorganization of the network, increasing the inter-hemisphere connections and the connectivity of locus coeruleus. ConclusionOur results provide new insights in the effects of atVNS on memory performance and brain connectivity extending our knowledge of the biological mechanisms of bioelectronics in medicine. HighlightsO_LIatVNS, delivered immediately after NORT training phase, improves memory persistence C_LIO_LIatVNS did not promote significant changes in brain c-Fos density C_LIO_LIatVNS induced a significant reorganization of c-Fos-based functional brain network C_LIO_LIatVNS produced an enhancement in correlated activity between hemispheres C_LIO_LIatVNS did not engage the prefrontal-retrosplenial axis, characteristic of the DMN C_LI

neuroscience↗