Biology subjects

Caceres, A.

Publications and source records attributed to Caceres, A..

13 recordsLinked to original sources

bioRxiv2026

Kappa Opioid-Oxytocin Interactions During Long-Term Partner Separation: Insights from PET Imaging in Titi Monkeys (Plecturocebus cupreus)

Social bonds are fundamental to health and well-being, and their disruption through partner separation is associated with significant physiological and psychological consequences. The kappa opioid receptor (KOR) system has been proposed as a key modulator of oxytocin (OT) release during partner separation, with prolonged separation hypothesized to trigger KOR downregulation in the paraventricular nucleus of the hypothalamus that disinhibits OT release over time (Bales & Rogers, 2022). However, this model has been difficult to assess non-invasively in primates. The present study used positron emission tomography (PET) with the KOR-selective radiotracer [11C]GR103545 to examine KOR availability in vivo across brain regions implicated in social bonding and separation distress in 16 pair-bonded titi monkeys using a within-subject two-week separation paradigm. Plasma OT, cerebrospinal fluid OT, and plasma cortisol were collected at each scan as complementary indices of peripheral and central OT signaling and physiological stress. We hypothesized that long-term separation would downregulate KORs in the hypothalamus and pituitary, indexed by reduced non-displaceable binding potential (BPND), consistent with the Bales and Rogers model, and increase plasma OT consistent with KOR downregulation disinhibiting OT release. Partner separation significantly elevated plasma cortisol in both sexes, confirming the physiological stress of the manipulation. A significant Condition x Sex interaction was observed for plasma OT, reflecting a crossover pattern in which males, who had significantly higher plasma OT than females at baseline, showed a significant decrease during separation while females showed a non-significant increase, though the sex difference during separation did not reach significance. KOR availability was significantly reduced in the nucleus accumbens during separation, with a non-significant trend toward reduction in the anterior cingulate cortex, while no significant condition effects were observed in the remaining a priori chosen regions. No significant sex effects or Condition x Sex interactions were observed in any a priori chosen PET region. Together, these findings provide the first in vivo neuroimaging evidence of KOR system engagement during partner separation in a pair-bonded primate species, and reveal a sex-dependent OT response to separation that extends and adds nuance to the Bales and Rogers (2022) framework.

neuroscience↗

bioRxiv2026

Brain Kappa Opioid Receptor Availability Across Stress and Social Buffering Conditions: A Positron Emission Tomography Study in Coppery Titi Monkeys

Social connectedness strongly influences health and longevity, and adult pair bonds provide psychological benefits distinct from other social relationships. Oxytocin (OT), corticotropin-releasing hormone (CRH), and opioids, play an important role in the formation and maintenance of pair bonds. Evidence suggests that OT modulates the stress response via the hypothalamic-pituitary-adrenal (HPA) axis, while the kappa ({kappa}) opioid system interacts with and may modulate OT signaling in contexts of stress and separation. In this study 20 coppery titi monkeys were exposed to a physical stressor under three social conditions: baseline (no stressor, partner present), stress (stressor, no partner present) and buffering (stressor, partner present). We predicted stress-induced dynorphin release would reduce {kappa}-opioid receptor availability measured via [{superscript 1}{superscript 1}C]GR103545 Positron Emission Tomography (PET) and lower cerebrospinal fluid (CSF) OT, whereas partner presence would mitigate dynorphin release and increase CSF OT, with reduced dynorphin inferred from higher {kappa}-opioid receptor radioligand binding. Our results show condition-dependent differences in [{superscript 1}{superscript 1}C]GR103545 binding in several brain regions, including the amygdala and hippocampus, with altered binding in both the stress and social buffering conditions. Cortisol levels were elevated in the stress condition compared to baseline. Females exhibited lower CSF OT levels during stress than at baseline, whereas plasma OT levels did not differ across conditions or between sexes. Spearman correlations revealed no significant associations between plasma and CSF OT. Together, these findings highlight the complex interaction between {kappa}-opioid signaling, OT, and HPA axis activity in the context of social relationships and highlight neuroendocrine mechanisms underlying stress regulation in pair-bonded species.

neuroscience↗

bioRxiv2025

Dysregulation of energy metabolism and calcium homeostasis in iPSC-derived neurons carrying Presenilin-1 M146L gene mutation

Impaired cellular activities, particularly in highly active cells such as neurons, are primarily supported by metabolic abnormalities and failures in Ca{superscript 2} homeostasis. Here, we provide an integrative analysis of human iPSC-derived neurons (iNs) carrying the Presenilin-1 M146L gene mutation (PS1M146L) and control cells (PS1control). PS1M146L iNs exhibited abnormal Ca{superscript 2} dynamics, a significant increase in key parameters of mitochondrial respiration, and higher intracellular ROS levels. KCl-evoked depolarisation was significantly lower in PS1M146L, suggesting a failure in maintaining the electrochemical gradient across the plasma membrane. Following thapsigargin stimulation, mitochondrial Ca{superscript 2} levels ([Ca{superscript 2}]m) were significantly reduced in PS1M146L, while [Ca{superscript 2}]m did not differ significantly between genotypes after treatment with bradykinin, suggesting that impairments in the [Ca{superscript 2}]m homeostasis are particularly evident under stress conditions and do not impact the 1,4,5-triphosphate (IP3) pathway. Since iNs of both genotypes were sensitive to the MCU-1 inhibitor, the deficits observed in PS1M146L could be the consequence of impairments in the ER-mitochondria contacts. Our results illustrate the utility of iNs carrying PS1 mutations in understanding how human neurons alter relevant pathways before neurodegeneration.

neuroscience↗

bioRxiv2025

High Glucose Diet Induces Hepatic Iron Overload Contributing to Metabolic Dysfunction

Iron is an essential biometal, critical in processes that include oxygen transport, mitochondrial respiration, and cell signaling. Iron dyshomeostasis is linked with hyperglycemia and associated metabolic disorders, but the underlying mechanisms are poorly understood. To investigate these mechanisms, we conducted a short-term, four-week, in vivo study on mice given water supplemented with glucose. The short time frame was sufficient to cause metabolic shifts in the liver towards triglyceride synthesis. We sought to comprehensively track iron trafficking by analyzing liver and serum markers of iron metabolism alongside LC-ICP-MS analysis of iron speciation, which is a new approach in this context. Glucose supplementation induced changes in iron regulation despite equal dietary iron intake between groups. Specifically, we observed increased uptake of transferrin-bound iron from the serum and an iron overload state in the liver. We developed and applied a cell-based models of this glucose-induced iron overload state and found that, on the one hand, the anti-diabetic drug metformin could restore iron regulation; on the other hand, the iron chelator, deferoxamine, could restore glucose metabolism. Taken together, our studies reveal that early hyperglycemia is sufficient to cause disruptions in iron regulations, pointing to iron overload as viable therapeutic target in metabolic dysfunction.

biochemistry↗

bioRxiv2025

Dynamic balance of H3K9me2 heterochromatin by CoREST-2 and RE-1 in growing neurons

A well-balanced chromatin dynamic is vital for the survival and physiology of all cells, including brain neurons. Heterochromatin, commonly associated with transcriptional silencing, also plays significant roles in maintaining genomic stability and facilitating DNA-repair processes. Notably, the bimethylation of histone H3 at lysine 9 (H3K9me2), a hallmark of repressive heterochromatin, supports the axonal specification of neurons. However, neuronal maintenance of H3K9me2 equilibrium remains understudied. In this work, we unveil a dynamic equilibrium of H3K9me2 regulated by the epigenetic factor CoREST-2 and RE-1 DNA motifs, sustaining axonal and dendritic outgrowth. Using primary cultures of rat hippocampal neurons and a combination of advanced imaging techniques, we observed an enriched nuclear accumulation of CoREST-2 and H3K9me2 along neuronal development. Genetic silencing of CoREST-2 induced axon-dendrite retraction, accompanied by an increase in nuclear levels of H3K9me2. To further investigate heterochromatin structure at the nanoscale, we employed STED nanoscopy and discovered that H3K9me2 is organized into small nanodomains, which were notably enlarged following the suppression of CoREST-2. In contrast, the genetic blockade of RE-1 DNA motifs led to axon-dendrite retraction alongside the disassembly of H3K9me2 nanodomains. These findings highlight that CoREST-2 and RE-1 sites actively shape neuronal H3K9me2 heterochromatin. Moreover, they uncover that maintaining a precise balance of H3K9me2 is essential for the extension of axons and dendrites, underpinning the connectivity and plasticity of brain neurons.

cell biology↗

bioRxiv2024

Tumor-derived hypoxic small extracellular vesicles promote endothelial cell migration and tube formation via ALS2/Rab5/β-catenin signaling

Tumor hypoxia has been associated with cancer progression, angiogenesis, and metastasis via modifications in the release and cargo composition of extracellular vesicles secreted by tumor cells. Indeed, hypoxic extracellular vesicles are known to trigger a variety of angiogenic responses via different mechanisms. We recently showed that hypoxia promotes endosomal signaling in tumor cells via HIF-1-dependent induction of the guanine exchange factor ALS2, which activates Rab5, leading to downstream events involved in cell migration and invasion. Since Rab5-dependent signaling is required for endothelial cell migration and angiogenesis, we explored the possibility that hypoxia promotes the release of small extracellular vesicles containing ALS2, which in turn activate Rab5 in recipient endothelial cells leading to pro-angiogenic properties. In doing so, we found that hypoxia promoted ALS2 expression and incorporation as cargo within small extracellular vesicles, leading to subsequent transfer to recipient endothelial cells, promoting cell migration, tube formation and downstream Rab5 activation. Consequently, ALS2-containing small extracellular vesicles increased early endosome size and number in recipient endothelial cells, which was followed by subsequent sequestration of components of the {beta}-catenin destruction complex within endosomal compartments, leading to stabilization and nuclear localization of {beta}-catenin. These events converged in the expression of {beta}-catenin target genes involved in angiogenesis. Knockdown of ALS2 in donor-tumor cells, which precluded its incorporation into small extracellular vesicles, prevented Rab5-downstream events and endothelial cell responses, which depended on Rab5 activity and guanine exchange factor activity of ALS2. These findings indicate that vesicular ALS2, secreted in hypoxia, promotes endothelial cell events leading to angiogenesis. Finally, these events might explain how tumor angiogenesis proceeds in hypoxic conditions.

cell biology↗

bioRxiv2024

Human neural rosettes secrete bioactive extracellular vesicles enriched in neuronal and glial cellular components

AO_SCPLOWBSTRACTC_SCPLOWExtracellular vesicles (EVs) play a critical role in the development of neural cells in the central nervous system (CNS). Human neural rosettes (hNRs) are radial cell structures that assemble from induced pluripotent stem cells (hiPSCs) and recapitulate some stages of neural tube morphogenesis. Here we show that hiPSCs and hNRs secrete EVs (hiPSC-EVs and hNR-EVs) with distinct protein cargoes. Remarkably, hNR-EVs carry neuronal and glial cellular components involved in CNS development. By in silico analysis, we found hNR-EVs protein signature is expressed in vivo and in vitro during human brain development. Importantly, hNR-EVs stimulate hiPSCs to change their cellular morphology with a significant reduction in the pluripotency regulator SOX2. Interestingly, these effects were inhibited by antibodies against an unexpected neuroglial cargo of hNR-EVs: the major proteolipid protein (PLP1). These findings show that hNRs secrete bioactive EVs containing neural components and might contribute as trophic factors during human CNS development.

cell biology↗

bioRxiv2023

Neutrophilia with damage to the blood-brain barrier and neurovascular unit following acute lung injury

BackgroundThe role of neutrophils in mediating neurovascular vulnerability has been increasingly implicated in various acute inflammatory models of neuroimmune crosstalk between the periphery and the brain. Whether neurovascular vulnerability is similarly modulated in the context of frequent, but not acute, inflammatory activation in the periphery is the aim of our study. Such a model of frequent inflammatory irritation is pertinent to understanding the neurologic risk of constant exposure to aerosolized environmental hazards leading to progressive pulmonary disease. MethodsTo model repeated pulmonary inflammation, we applied a three-dose regimen of intranasal (i.n.) lipopolysaccharide (LPS) in C57BL/6J mice and studied the impact on the inflammatory environment of the brain, with a specific focus on neutrophil dynamics at the neurovascular unit (NVU). Tissue and circulatory inflammatory profiles were screened via bronchoalveolar lavage (BAL) protein content and cellularity, transcript analysis of brain tissue, and flow cytometry of peripheral blood. Intravital two-photon microscopy (2PM) of the brain vasculature identified neutrophil dynamics at the NVU. Immunofluorescence validated neutrophil dynamics and identified neuroinflammatory hallmarks and peripheral immune factor interactions at the NVU. In vivo findings were corroborated and replicated in murine and human microphysiological systems (MPS) modeling the blood-brain barrier as a proxy demonstration of the translational relevance of our findings. Results2PM of tdTomato-Ly6G+ neutrophils demonstrated increased levels of circulating neutrophils and corresponding engagement with the brain vasculature after the three-dose repeated i.n. exposure regimen. Neutrophilia at the NVU was corroborated with increased transcript levels of Ly6G and other pro-inflammatory markers. This coordination between endothelial physiology and neutrophil phenotypes was recapitulated in murine and human MPS models. System-wide neutrophilia in the lung and circulation was found to be cotemporaneous to neutrophilia at the NVU based on the cellularity of BAL and peripheral blood samples collected at the same endpoints. Immunohistochemical analysis of brain tissue implicates temporal coordination between vascular surface adhesion molecules with changes in neutrophil dynamics from adhesion, crawling, stalling, and transmigration. Extravasation of neutrophils was complemented by sustained paravascular deposition of fibrinogen and microgliosis up to 72 hours after the final i.n. dosing. Microglia-associated effector functions for synaptic pruning and regulation of neutrophil activity demonstrated distinct temporal profiles. ConclusionsOur results identify systemic levels of neutrophilia accompanied by ingress and extravascular accumulation in brain parenchyma that correlated with sustained microglial activation. This neutrophil-centric lung-brain interaction is complemented by the observation of paravascular fibrinogen deposition that alters synaptic metabolism. Thus, we propose a mechanistic role for neutrophilia and associated inflammatory dysregulation as essential mediators along the lung-brain neuroimmune axis in a generalizable model of repeated respiratory exposure to inflammatory agents. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC="FIGDIR/small/562508v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@113d747org.highwire.dtl.DTLVardef@19a8a5corg.highwire.dtl.DTLVardef@f1a1eaorg.highwire.dtl.DTLVardef@1bd23c7_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Dual spatio-temporal regulation of axon growth and microtubule dynamics by RhoA signaling pathways

RhoA plays a crucial role in neuronal polarization, where its action restraining axon outgrowth has been thoroughly studied. We now report that RhoA has not only inhibitory but also a stimulatory effect on axon development depending on when and where exerts its action and the downstream effectors involved. In cultured hippocampal neurons, FRET imaging revealed that RhoA activity selectively localizes in growth cones of undifferentiated neurites, while in developing axons it displays a biphasic pattern, being low in nascent axons and high in elongating ones. RhoA-Rho kinase (ROCK) signaling prevents axon initiation but has no effect on elongation, while formin inhibition reduces axon extension without significantly altering initial outgrowth. Besides, RhoA-mDia promotes axon elongation by stimulating growth cone microtubule stability and assembly, as opposed to RhoA-ROCK that restrains growth cone microtubule assembly and protrusion. Finally, we show that similar mechanisms might operate during axonal regeneration, with RhoA-ROCK slowing axon regrowth after axotomy and RhoA-mDia favoring extension of regenerated axons.

neuroscience↗

bioRxiv2019

Historical recombination variability contributes to deciphering the genetic basis of phenotypic traits

Recombination is a main source of genetic variability. However, the potential role of the variation generated by recombination in phenotypic traits, including diseases, remains unexplored as there is currently no method to infer chromosomal subpopulations based on recombination patterns differences. We developed recombClust, a method that uses SNP-phased data to detect differences in historic recombination in a chromosome population. We validated our method by performing simulations and by using real data to accurately predict the alleles of well known recombination modifiers, including common inversions in Drosophila melanogaster and human, and the chromosomes under selective pressure at the lactase locus in humans. We then applied recombClust to the complex human 1q21.1 region, where nonallelic homologous recombination produces deleterious phenotypes. We discovered and validated the presence of two different recombination histories in these regions that significantly associated with the differential expression of ANKRD35 in whole blood and that were in high linkage with variants previously associated with hypertension. By detecting differences in historic recombination, our method opens a way to assess the influence of recombination variation in phenotypic traits.

bioinformatics↗

bioRxiv2019

A robust estimation of mosaic loss of chromosome Y from genotype-array-intensity data to improve disease risk associations and transcriptional effects

Accurate protocols and methods to robustly detect the mosaic loss of chromosome Y (mLOY) are needed given its reported role in cancer, several age-related disorders and overall male mortality. Intensity SNP-array data have been used to infer mLOY status and to determine its prominent role in male disease. However, discrepancies of reported findings can be due to the uncertainty and variability of the methods used for mLOY detection and to the differences in the tissue-matrix used. We proposed MADloy, the first publicly available software tool that incorporates previous methods and includes a new robust approach, allowing efficient calling in large studies and comparisons between methods. The new method implemented in MADloy optimizes mLOY calling by correctly modeling the underlying reference population with no-mLOY status and incorporating B-deviation information. We observed improvements in the calling accuracy with respect to previous methods, using experimentally validated samples, and an increment in the statistical power to detect associations with disease and mortality, using simulation studies and real dataset analyses. We applied MADloy to detect the increment of mLOY cellularity in blood on 18 individuals after 3 years, and to confirm that its detection in saliva was sub-optimal (41%). We illustrate the use of MADloy to detect the down-regulation genes in the chromosome Y in kidney and bladder tumors with mLOY, and to perform pathway analyses for the detection of mLOY in blood. MADloy is a new software tool implemented in R for easy and robust calling of mLOY status in men aimed to facilitate its study in large epidemiological studies.

genomics↗

bioRxiv2019

Three-dimensional total internal reflection fluorescence nanoscopy with sub-10 nm resolution

Single-molecule localization microscopy (SMLM) enables far-field imaging with lateral resolution in the range of 10 to 20 nanometres, exploiting the fact that the centre position of a single molecules image can be determined with much higher accuracy than the size of that image itself. However, attaining the same level of resolution in the axial (third) dimension remains challenging. Here, we present SIMPLER, a photometric method to decode the axial position of single molecules in a total internal reflection fluorescence (TIRF) microscope. SIMPLER requires no hardware modification whatsoever to a conventional TIRF microscope, and complements any 2D SMLM method to deliver 3D images with nearly isotropic nanometric resolution. Examples of the performance of SIMPLER include the visualization of the nuclear pore complex through dSTORM with sub-20 nm resolution and of microtubule cross-sections resolved with sub-10 nm through DNA-PAINT.

biophysics↗

bioRxiv2017

A measure of agreement to distinguish between condition levels: Reproducibility of co-expression networks across tissues

There is great interest to study how co-expression gene networks change across tissues. However, the reproducibility assessment of these studies is challenged by a lack of fully confirmatory experiments from independent researchers. While an increment in the number of studies with expression data for several tissues is expected, statistical measures are still needed to assess the reproducibility between studies. We identified a gap in the statistical literature concerning the assessment of agreement between studies that independently measure the effect of a varying condition on a population sample. The gap precluded us to test, using standard statistics, the level of agreement between the GTEX (RNAseq) and BRAINEAC (microarray) studies to distinguish the structure of co-expression networks across four brain tissues. We, therefore, generalized a classical measure of agreement, Cohens{kappa} , derived its distributional characteristics and determined its reliability properties. In the gene expression studies, we found full agreement of genome-wide networks in BRAINEAC benchmarked against GTEX, and highest agreement for brain specific pathways. Our highly interpretable measure can contribute to anticipated efforts on reproducibility research.

systems biology↗