Biology subjects

Gaspar, R.

Publications and source records attributed to Gaspar, R..

6 recordsLinked to original sources

bioRxiv2026

BCKDK Inhibitors Directly Antagonize Angiotensin II Type 1 Receptor and Induce Vasodilation Independently of BCAA Catabolism or BCKDK

Branched-chain amino acids (BCAA) have been implicated in diabetes and heart failure, leading to ongoing clinical trials with inhibitors of BCKDK, a key regulator of BCAA catabolism. We have previously shown that these inhibitors promote vasodilation and lower blood pressure, well-known cardioprotective effects, but how this occurs remained unclear. We show here, using explanted vessels, in vivo hemodynamics and telemetry, and genetically modified mice, that the vasodilatory effect of BCKDK inhibitors is direct, rapid, independent of nitric oxide, independent of BCAA catabolism, and most strikingly, independent of BCKDK itself. Instead, we demonstrate, using structural and biochemical studies, that BCKDK inhibitors directly antagonize the angiotensin II type I receptor (AT1R) and consequent angiotensin-mediated vasoconstriction. These data demonstrate a strong off-target effect of BCKDK inhibitors, independent of BCAA or BCKDK, which may explain their cardioprotective effects but also questions if this protection would be additive to existing AT1R blockers.

physiology↗

bioRxiv2025

Micronuclear collapse under oxidative stress drives amphisome-mediated export of DNA in Parkinson disease

The diversity of extracellular vesicle (EV) subpopulations and their impact on intercellular communication are increasingly recognized, but how organelle dysfunction shapes EV content in neurodegenerative diseases remains unclear. Mitochondrial and lysosomal functional defects are hallmarks of Parkinsons disease (PD). Here we uncover a novel pathway linking this dysfunctional axis to EV remodeling and immune activation. We show that mitochondrial reactive oxygen species (ROS) induce genomic instability and micronuclei formation in PD fibroblasts, with ruptured micronuclei being sequestered into amphisomes and exported through small EVs. These EVs are enriched in oxidized mitochondrial and nuclear DNA, which potently stimulate microglial inflammatory responses. Mechanistically, this work identifies micronuclei not as passive byproducts of genome instability but as active intermediates in EV cargo loading. Importantly, treatment with the mitochondria-targeted antioxidant AntiOxCIN4 elicited a mitohormetic response, enhancing ATM-mediated DNA damage repair, restoring mitochondrial dynamics, and improving lysosomal function. This reduced the incorporation of oxidized DNA into EVs and blunted their pro-inflammatory activity. Together, our findings reveal a previously unrecognized mechanism by which mitochondrial-lysosomal dysfunction drives the release of DNA-enriched EVs that fuel neuroinflammation in a neurodegenerative context. Targeting mitochondrial quality control to limit oxidized cargo in EVs emerges as a potential strategy to mitigate early inflammatory events in PD.

neuroscience↗

bioRxiv2025

Genetic variance in spider mites reveals trade-offs: lines with higher growth rate suffer stronger competition but exert stronger reproductive interference

O_LIWithin-species individual variation has been gaining increased attention in ecological studies of species interactions. Yet, these studies rarely consider genetic variation and potential genetic correlations among traits. Moreover, traits beyond those associated with trophic interactions are mostly overlooked. Filling these gaps is important to fully understand the relevance of trait variation in both the ecology and evolution of species interactions. C_LIO_LIWe addressed this using inbred lines of Tetranychus cinnabarinus, a spider mite species that often engages in antagonistic interactions with its congeneric T. urticae. Specifically, we measured (a) the intrinsic growth rate and the sex ratio in the absence of food competition and reproductive interference; (b) food competition against a density gradient of con- or heterospecific competitors in absence of reproductive interference; (c) reproductive interference in absence of food competition; and (d) the body size of adult females and males. C_LIO_LIWe found significant genetic variance (i.e., broad-sense heritability) among lines for all variables except for the effect of T. cinnabarinus on its heterospecific competitor via food competition. Moreover, we showed that lines with higher intrinsic growth were more sensitive to intra- and inter-specific competition for food but exerted stronger reproductive interference on heterospecifics. In addition, the higher the proportion of sons produced by a line, the more resilient it was to reproductive interference but also the lower its growth rate. No genetic correlations were found between any variable and body size. C_LIO_LIOur results indicate that considering the genetic correlations among traits involved in both trophic and sexual interactions is key to understanding the role of individual variation in species interactions and their evolution. C_LI

evolutionary biology↗

bioRxiv2025

Liver lipid droplet cholesterol content is a key determinant of metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) represents a progressive form of steatotic liver disease which increases the risk for fibrosis and advanced liver disease. The accumulation of discrete species of bioactive lipids has been postulated to activate signaling pathways that promote inflammation and fibrosis. However, the key pathogenic lipid species is a matter of debate. We explored candidates using various dietary, molecular, and genetic models. Mice fed a choline-deficient L-amino acid-defined high-fat diet (CDAHFD) developed steatohepatitis and manifested early markers of liver fibrosis associated with increased cholesterol content in liver lipid droplets within 5 days without any changes in total liver cholesterol content. Treating mice with antisense oligonucleotides (ASOs) against Coenzyme A synthase (Cosay) or treatment with bempedoic acid or atorvastatin decreased liver lipid droplet cholesterol content and prevented CDAHFD-induced MASH and the fibrotic response. All these salutary effects were abrogated with dietary cholesterol supplementation. Analysis of human liver samples demonstrated that cholesterol in liver lipid droplets was increased in humans with MASH and liver fibrosis and was higher in PNPLA3 I148M (variants rs738409) than in HSD17B13 variants (rs72613567). Together, these data identify cholesterol in liver lipid droplets as a critical mediator of MASH and demonstrate that COASY knockdown and bempedoic acid are novel therapeutic approaches to reduce liver lipid droplet cholesterol content and thereby prevent the development of MASH and liver fibrosis. Significance StatementMetabolic dysfunction-associated steatohepatitis (MASH) is a progressive liver disease linked to fibrosis. The role of specific lipid species in its pathogenesis remains debated. Using dietary, molecular, and genetic models, we found that mice on a choline-deficient, high-fat diet (CDAHFD) developed steatohepatitis and early fibrosis, marked by increased cholesterol in liver lipid droplets within five days. Targeting COASY with antisense oligonucleotides or treating with bempedoic acid or atorvastatin reduced lipid droplet cholesterol and prevented MASH. However, dietary cholesterol supplementation negated these effects. Human liver samples confirmed elevated lipid droplet cholesterol in MASH and fibrosis, especially in PNPLA3 I148M carriers. These findings highlight cholesterol reduction as a potential MASH therapy.

pathology↗

bioRxiv2024

Dynamic representation of appetitive and aversive stimuli in nucleus accumbens shell D1- and D2-medium spiny neurons

The nucleus accumbens (NAc) is a key brain region for motivated behaviors, yet how distinct neuronal populations encode appetitive or aversive stimuli remains undetermined. Using microendoscopic calcium imaging, we tracked NAc shell D1- or D2-medium spiny neurons (MSNs) activity during exposure to stimuli of opposing valence and associative learning. Despite drift in individual neurons coding, both D1- and D2-population activity was sufficient to discriminate opposing valence unconditioned stimuli, but not predictive cues. Notably, D1- and D2-MSNs were similarly co-recruited during appetitive and aversive conditioning, supporting a concurrent role in associative learning. Conversely, when contingencies changed, there was an asymmetric response in the NAc, with more pronounced changes in the activity of D2-MSNs. Optogenetic manipulation of D2-MSNs provided causal evidence of the necessity of this population in the extinction of aversive associations. Our results reveal how NAc shell neurons encode valence, Pavlovian associations and their extinction, and unveil new mechanisms underlying motivated behaviors.

neuroscience↗

bioRxiv2022

Understanding Hybrid Lipid-Polymer Gene Delivery Nanoparticle Assembly with Fluorescence Cross Correlation Spectroscopy

Hybrid lipid-polymer-nucleic acid nanoparticles (LPNPs) provide unique delivery strategies for nonviral gene therapy. Since LPNPs consist of multiple components that can undergo different pairwise interactions between them, LPNPs are difficult to prepare and characterize. Here we demonstrate that the interaction between the polycation (polylysine) and DNA is robust through an innovative implementation of fluorescence cross-correlation spectroscopy, implying that the polycation is not displaced by cationic liposomes in the formation process. Hence, the polycation-DNA cores (polyplexes) and liposome shells must be oppositely charged to associate. Furthermore, we prove that the liposome:polyplex number ratio ({rho}N) is the primary critical parameter to predict stable LPNP formation. We establish that{rho} N [≥] 1 is required to ensure that every polyplex is enveloped by a liposome, avoiding the coexistence of oppositely charged species and thereby inhibiting aggregation. We expect our observations to be valid for the formation of many other LPNPs and composite nanomaterials.

biophysics↗