Biology subjects

Mora, S.

Publications and source records attributed to Mora, S..

9 recordsLinked to original sources

bioRxiv2025

Effect of Age and Sex on BCAA Metabolism in Mice

Increased plasma levels of branched-chain amino acids (BCAA) have been implicated in insulin resistance. This condition worsens with age, but plasma BCAA levels are downregulated in old men. The effect of age and/ sex on BCAA metabolism has been rarely studied. Thus, the objective of this study was to analyze how age and sex affect BCAA levels and their metabolism in mouse tissues. Male and female young (4-month) and old (18-months) CD2F1 mice were used. BCAA levels and relevant BCAA metabolic enzymes abundance/activity in plasma, muscle, liver, adipose tissue, and heart were analyzed. Old males exhibited greater plasma BCAA concentrations compared to young males and old females, but plasma branched-chain ketoacid (BCKA) levels were lower in old mice in both sexes. Intracellular BCAA levels were lower in skeletal muscle and heart from old mice independent of sex. There was an age-sex interaction in the lever in that reduced total BCAA was seen only in old male animals. In adipose tissue, total BCKA levels were higher in old male animals. Skeletal muscle abundance of the BCAA transporter LAT1 was reduced in old females compared to young females. In the liver, female mice had higher levels of LAT1 than male mice independent of age, while total BCKD was reduced in old females compared to old males. Pp2Cm levels were reduced in old animals independent of sex. In conclusion, while there were some changes in plasma and tissue BCAA/BCKA levels in response to age/sex, such changes were largely not consistent with changes in tissue BCAA catabolic enzyme abundance/activity. This suggests that protein levels of BCAA catabolic enzymes are preserved in aging in healthy animals and likely only become dysregulated in disease states.

physiology↗

bioRxiv2025

Sex Differences in Cachexia Outcomes and Branched-Chain Amino Acid Metabolism Following Chemotherapy in Aged Mice

Cachexia is a complex muscle wasting syndrome that affects majority of hospitalized cancer patients receiving chemotherapy. It is often unresponsive to nutritional interventions, including provision of branched-chain amino acids (BCAA: leucine, isoleucine and valine). BCAA are anabolic for skeletal muscle. We wondered whether their ineffectiveness in managing cachexia might be related to altered metabolism of these amino acids, a subject that has received minimal attention. Because estrogen limits BCAA catabolism, we hypothesized that the effects of chemotherapy on cachexia in old mice would be worse in males compared to females, and that this would be related to greater tissue release of BCAA in males. To better reflect age population for which cachexia is an issue, we treated aged male and female mice (18{+/-}2 months) with the chemotherapy drug cocktail FOLFIRI (50mg/kg 5-fluorouracil (5FU), 90mg/kg Leucovorin, and 24mg/kg CPT11) or vehicle twice per week for 6 weeks. This cocktail is used in treating colon cancer. Metabolism and concentrations of the BCAA and their metabolites were measured in plasma and tissues. There was a main effect of chemotherapy, reflected in reduced body weight, skeletal muscle, myofibrillar protein content, anabolic signalling and protein synthesis. In response to chemotherapy, males showed worsened outcomes for skeletal muscle weight and ubiquitinated proteins; they also had higher total plasma BCAA but reduced muscle BCAA. There was a main effect of chemotherapy in reducing the expression of the BCAA transporter LAT1. In response to chemotherapy, gastrocnemius muscle of males but not females had reduced inhibitory phosphorylation of BCKD-E1ser293, corresponding with increased activity of this enzyme. Chemotherapy reduced muscle and liver ketoacids of the BCAA only in females. These data suggest that sex differences in BCAA catabolism may be linked to the severity of chemotherapy-induced muscle damage and interventions against cachexia need to take this into account.

physiology↗

bioRxiv2025

Myofibrillar protein accumulation but reduced protein synthesis in PDCD4-depleted myotubes

Skeletal muscle is critical to whole-body functionality and homeostasis. The mammalian/mechanistic target of rapamycin complex 1 (mTORC1) is a nutrient/growth-factor sensitive positive regulator of skeletal muscle mass. Amongst other substrates, mTORC1 phosphorylates the ribosomal protein S6 kinase (S6K1). Activated S6K1 acts through multiple effectors, including programmed cell death 4 (PDCD4), to activate mRNA translation and protein synthesis. Much of what is known about PDCD4 is in non-muscle cells. We previously demonstrated that the effect of PDCD4 differs between myoblasts and myotubes. Here, we showed that PDCD4 depletion in L6 and C2C12 myotubes enhanced myotube diameter (+36%) and accumulation of myofibrillar proteins (+163 - 237%). These effects occurred along with increased phosphorylation of AKTser473 (+85%) and of the mTORC1 substrate S6K1thr389 (+152%), but protein synthesis was suppressed. There was increased phosphorylation of FoxO3aser253 (+250%) and a corresponding reduction in the expression of the muscle protein ubiquitin ligase MuRF1 (-44%), but there was no significant effect on measures of proteolysis or autophagy. In starved myotubes treated with the proteasome inhibitor MG132, accumulation of ubiquitinated proteins was attenuated in PDCD4-depleted cells. PDCD4 depletion did not augment measures of myotube contraction but was associated with reduced ATP and intracellular amino acid levels. Finally, AKT inhibition partially attenuated the effect of PDCD4 depletion on myofibrillar protein abundance. In summary, myofibrillar protein accumulation in PDCD 4-depleted myotubes did not lead to improved myotube function, likely due to reduced energy level. Our data point to a pivotal role for PDCD4 in regulating myotube size and metabolism.

physiology↗

bioRxiv2025

Predicting therapeutic windows for synaptic intervention in ALS

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive breakdown of neural circuits which leads to motoneuron death. Earlier work from our lab showed that dysregulation of inhibitory V1 interneurons precedes the degeneration of excitatory V2a interneurons and motoneurons and that stabilizing V1-motoneuron connections improved motor function and saved motoneurons in the SOD1G93A ALS mouse model. However, the optimal timing for this intervention remains unclear. To address this, we developed a spiking neural network model of spinal locomotor circuits to simulate healthy and ALS-like conditions. By modeling changes in network connectivity and synaptic dynamics, we predict that V1 dysregulation induces hyperexcitation in motoneurons which is preferentially observed in flexor motoneurons leading to the disruption of flexor-extensor coordination, and potentially contributing to selective vulnerability of flexor motoneurons. Stabilizing V1 synapses preserved motor output even after motoneuron loss, suggesting that therapeutic benefit is possible into symptomatic stages. However, model predictions also highlighted that after sustained synaptic loss and the development of slower synaptic dynamics within the network, synaptic stabilization leads to maladaptive extensor-biased activity, suggesting that excitatory/inhibitory balance impacts treatment effectiveness. Finally, the model indicated that V1 stabilization could lead to rescue of the V2a excitatory interneurons, a finding that we were able to confirm experimentally in the SOD1G93A ALS mouse model. By exploring different scenarios of synaptic loss and cell dysregulation during synaptic stabilization, our models provide a framework for predicting candidate time windows for spinal circuit interventions, which may guide future preclinical investigations.

neuroscience↗

bioRxiv2024

From Nutritional Patterns to Behavior: High-Fat Diet Influences on Inhibitory Control, Brain Gene Expression and Metabolomics in Rats

BackgroundImpulsive and compulsive behaviors are associated with inhibitory control deficits. Diet plays a pivotal role in normal development, impacting both physiology and behavior. However, the specific effects of high-fat diets (HFD) on inhibitory control have not received adequate attention. ObjectivesThis study aimed to explore how exposure to an HFD from postnatal day (PND) 33 to PND77 affects impulsive and compulsive behaviors. MethodsThe experiment involved 40 Wistar rats, half of which were male and subjected to the HFD or Chow diets. Several tasks were employed to assess behavior, including the Variable Delay to Signal (VDS), the Five Choice Serial Reaction Time Task (5-CSRTT), the Delay Discounting Task (DDT), and the Rodent Gambling Task (rGT). Genetic analyses were performed on the frontal cortex, and metabolomics and fatty acid profiles were examined using stool samples collected on PND298. ResultsThe study revealed that rats exposed to the HFD exhibited heightened impulsivity in the VDS and in the 5-CSRTT, suggesting an increase in motor impulsivity. Notably, no significant effect was observed in the DDT. Surprisingly, the HFD-exposed group demonstrated reduced levels of impulsive-like behaviors, and a different decision making, in the rGT. Furthermore, abnormal gene regultation linked to brain plasticity and dopamine were identified in the frontal cortex. Metabolomics analysis of stool samples, collected in adulthood, indicated lower levels of fatty acids. DiscussionThese results suggest that HFD exposure during adolescence may create a lasting vulnerability to inhibitory control deficits, specifically in terms of motor impulsivity, and in gene expression as well as in metabolomics profile.

neuroscience↗

bioRxiv2022

Stabilization of V1 interneuron-motor neuron connectivity ameliorates motor phenotype in a mouse model of ALS

Loss of connectivity between spinal V1 inhibitory inter-neurons and motor neurons is found early in disease in the SOD1G93A ALS mice. Such changes in premotor inputs can contribute to homeostatic imbalance of vulnerable motor neurons. Here, we show, for the first time, that stabilization of V1 synapses by overexpression of the Extended Synap-totagmin 1 presynaptic organizer increases motor neuron survival and ameliorates motor phenotypes, demonstrating that interneurons can be a potential target to attenuate ALS symptoms.

neuroscience↗

bioRxiv2022

NLP-based tools for localization of the Epileptogenic Zone in patients with drug-resistant focal epilepsy

BackgroundDrug-resistant focal epilepsy, defined by failure of two antiepileptic drugs, affects about 30% of patients with epilepsy. Epilepsy surgery may represent an alternative options for this population. However, defining the epileptogenic zone to be surgically removed requires highly specialised medical expertise as well as advanced technologies. The aim of this work is building a cost-effective support system based on text, in particular based on the semiological descriptions of the seizures (temporal vs extratemporal lobe; right vs left hemisphere), in order to predict the localization of seizure origin. MethodsAmong a population of 121 surgically treated and seizure-free drug-resistant patients suffering with focal epilepsy, recruited at the Niguarda Hospital in Milan, we extracted a total number of 509 descriptions of seizures. After a data pre-processing phase, we used natural language processing tools to build numerical representations of the seizures descriptions, both using embedding and countbased methods. We then used machine learning models performing a binary classification into right/left and temporal/extra-temporal. ResultsAll predictive models show a better performance when using the representations relying on embedding models respect to count-based ones. Between all the combinations of representations and classifiers, the best performance obtained in terms of F1-score is 84.7% {+/-} 0.6. DiscussionThis preliminary work reached encouraging results considering both localization tasks. The main advantage is that no specific knowledge about epilepsy is used to build the models, rendering our pipeline applicable also in other scenarios. The major limitation lies in the fact that the text is highly specific to the writer.

bioengineering↗

bioRxiv2020

Scalable and accurate automated method for neuronal ensemble detection in spiking neural networks

We propose a novel, scalable, and accurate automated method for detecting neuronal ensembles from a population of spiking neurons. Our approach offers a simple yet powerful tool to study ensemble activity. It allows the participation of neurons in different ensembles, has few parameters to tune and is computationally efficient. We used spike trains of retinal ganglion cells obtained from multi-electrode array recordings under a simple ON-OFF light stimulus to test our method. We found a consistent stimuli-evoked ensemble activity intermingled with spontaneously active ensembles and irregular activity. Our results suggest that the early visual system activity is already organized in clearly distinguishable functional ensembles. To validate the performance and generality of our method, we generated synthetic data, where we found that our method accurately detects neuronal ensembles for a wide range of simulation parameters. Additionally, we found that our method outperforms current alternative methodologies. Finally, we provide a Graphic User Interface, which aims to facilitate our methods use by the scientific community. Author summaryNeuronal ensembles are strongly interconnected groups of neurons that tend to fire together (Hebb 1949). However, even when this concept was proposed more than 70 years ago, only recent advances in multi-electrode arrays and calcium imaging, statistical methods, and computing power have made it possible to record and analyze multiple neurons activities spiking simultaneously, providing a unique opportunity to study how groups of neurons form ensembles spontaneously and under different stimuli scenarios. Using our method, we found that retinal ganglion cells show a consistent stimuli-evoked ensemble activity, and, when validated with synthetic data, the method shows good performance by detecting the number of ensembles, the activation times, and the core-cells for a wide range of firing rates and number of ensembles accurately.

neuroscience↗

bioRxiv2020

Trim39 regulates neuronal apoptosis by acting as a SUMO-targeted E3 ubiquitin-ligase for the transcription factor NFATc3

NFATc3 is the predominant member of the NFAT family of transcription factor in neurons, where it plays a pro-apoptotic role. Mechanisms controlling NFAT protein stability are poorly understood. Here we identify Trim39 as an E3 ubiquitin-ligase of NFATc3. Indeed, Trim39 ubiquitinates NFATc3 in vitro and in cells, whereas silencing of endogenous Trim39 decreases NFATc3 ubiquitination. We also show that Trim17 inhibits Trim39-mediated ubiquitination of NFATc3 by reducing both the E3 ubiquitin-ligase activity of Trim39 and the NFATc3/Trim39 interaction. Moreover, mutation of SUMOylation sites in NFATc3 or SUMO-interacting motif in Trim39 reduces the NFATc3/Trim39 interaction and Trim39-induced ubiquitination of NFATc3. As a consequence, silencing of Trim39 increases the protein level and transcriptional activity of NFATc3, resulting in enhanced neuronal apoptosis. Likewise, a SUMOylation-deficient mutant of NFATc3 exhibits increased stability and pro-apoptotic activity. Taken together, these data indicate that Trim39 modulates neuronal apoptosis by acting as a SUMO-targeted E3 ubiquitin-ligase for NFATc3.

cell biology↗