Biology subjects

Trovo, L.

Publications and source records attributed to Trovo, L..

6 recordsLinked to original sources

bioRxiv2025

Neuronal compartmentalization results in impoverished axonal mitochondria

Mitochondria differ depending on their location within a neuron. Morphological heterogeneity between somatic, dendritic, and axonal mitochondria is well established. Emerging evidence suggests that further specialization is needed to meet the unique demands of different neuronal compartments. However, the molecular and functional diversity of mitochondria within a neuron remains poorly understood. Here, we utilized proteomics in MitoTag mice to profile somatodendritic and axonal mitochondria across four distinct neuron types, thereby generating a compendium of intracellular mitochondrial diversity. Combining proteomics, functional, and immunofluorescence analyses, we demonstrated that axonal mitochondria are not defined by the presence of unique proteins, but rather by the selective loss or preservation of specific pathways compared to their somatodendritic counterparts. This results in "impoverished" axonal mitochondria, which are characterized by diminished mtDNA expression and impaired oxidative phosphorylation yet retain other pathways, such as fatty acid metabolism. Bioinformatic analyses of multiomic data identified local translation as one mechanism underlying compartment-specific diversity. Together, these findings provide a comprehensive in vivo framework for understanding mitochondrial specialization across neuronal compartments.

neuroscience↗

bioRxiv2025

Prenatal Acetaminophen Exposure Does Not Disrupt Human Fetal Brain Development in Cortical Organoid Models

Acetaminophen (APAP) is the most widely used analgesic during pregnancy, yet its effects on prenatal human brain development remain incompletely understood. Epidemiological studies have reported inconsistent associations between prenatal APAP exposure and later neurodevelopmental outcomes, underscoring the need for mechanistic evaluation in human-relevant developmental models. Here, we examined how APAP influences early cortical development using induced pluripotent stem cell-derived cortical organoids (COs) generated from six independent lines. Organoids were exposed to physiologically relevant APAP concentrations (25, 50, and 100 M) for 5 days beginning at day 21 of differentiation, corresponding to late first-trimester cortical development. We assessed organoid growth, apoptosis, differentiation, synaptic maturation, transcriptomic profiles using bulk and single-nucleus RNA sequencing (snRNA-seq), and functional network activity using multielectrode array recordings up to 4 months. APAP exposure did not affect organoid size, cytoarchitecture, or viability. Neuronal and progenitor cell proportions, as well as synaptic puncta density were unchanged. Bulk RNA-seq revealed subtle transcriptional changes only at the highest dose (16 differentially expressed genes at 100 M), enriched for neurodevelopmental pathways. In contrast, snRNA-seq at 3 months revealed no changes in cell type composition or gene expression. Consistent with these findings, electrophysiological measures including firing rate, burst frequency, and network synchrony, were indistinguishable from controls. Together, these results indicate that exposure to therapeutic APAP concentrations during a critical window of early cortical development produces minimal molecular perturbations without detectable consequences. This study provides mechanistic evidence indicating that, in this human organoid model, recommended APAP exposure is not associated with detectable disruptions in pathways implicated in brain development.

neuroscience↗

bioRxiv2023

Targeting the TCA cycle can ameliorate widespread axonal energy deficiency in neuroinflammatory lesions

Inflammation in the central nervous system (CNS) can impair the function of neuronal mitochondria and contributes to axon degeneration in the common neuroinflammatory disease multiple sclerosis (MS). Here we combine cell type-specific mitochondrial proteomics with in vivo biosensor imaging to dissect how inflammation alters the molecular composition and functional capacity of neuronal mitochondria. We show that neuroinflammatory lesions in the mouse spinal cord cause widespread and persisting axonal ATP deficiency, which precedes mitochondrial oxidation and calcium overload. This axonal energy deficiency is associated with impaired electron transport chain function, but also an upstream imbalance of tricarboxylic acid (TCA) cycle enzymes, with several, including key rate-limiting, enzymes being depleted in neuronal mitochondria in experimental models and in MS lesions. Notably, viral overexpression of individual TCA enzymes can ameliorate the axonal energy deficits in neuroinflammatory lesions, suggesting that TCA cycle dysfunction in MS may be amendable to therapy.

neuroscience↗

bioRxiv2022

Soluble amyloid-β precursor peptide does not regulate GABAB receptor activity

Amyloid-{beta} precursor protein (APP) regulates neuronal activity through the release of secreted APP (sAPP) acting at cell-surface receptors. APP and sAPP were reported to bind to the extracellular sushi domain 1 (SD1) of GABAB receptors (GBRs). A 17 amino-acid peptide (APP17) derived from APP was sufficient for SD1 binding and shown to mimic the inhibitory effect of sAPP on neurotransmitter release and neuronal activity. The functional effects of APP17 and sAPP were similar to those of the GBR agonist baclofen and blocked by a GBR antagonist. These experiments led to the proposal that sAPP activates GBRs to exert its neuronal effects. However, whether APP17 and sAPP indeed influence classical GBR signaling pathways in heterologous cells was not analyzed. Here, we confirm that APP17 binds to GBRs with nanomolar affinity. However, biochemical and electrophysiological assays indicate that APP17 does not influence GBR activity in heterologous cells. Moreover, we found no evidence for APP17 regulating K+ currents in cultured neurons, neurotransmitter release in brain slices, or neuronal activity in vivo. Our results show that APP17 is not a functional GBR ligand and indicate that sAPP exerts neuronal effects through receptors other than GBRs.

neuroscience↗

bioRxiv2022

Glutathione in the nucleus accumbens regulates motivation to exert reward-incentivized effort

Emerging evidence is implicating mitochondrial function and metabolism in the nucleus accumbens in motivated performance. However, the brain is vulnerable to excessive oxidative insults resulting from neurometabolic processes and whether antioxidant levels in the nucleus accumbens contribute to motivated performance is not known. Here, we identify a critical role for glutathione (GSH), the most important endogenous antioxidant in the brain, in motivation. Using proton magnetic resonance spectroscopy (1H-MRS) at ultra-high field in both clinical and preclinical populations, we establish that higher accumbal GSH levels are highly predictive of better, and particularly steady performance over time in effort-related tasks. Causality was established in preclinical in vivo experiments that, first, showed that down-regulating GSH levels through micro-injections of the GSH synthesis inhibitor buthionine sulfoximine in the nucleus accumbens impaired effort-based reward-incentivized performance. In addition, systemic treatment with the GSH precursor N-acetyl-cysteine (NAC) increased accumbal GSH levels and led to improved performance, potentially mediated by a cell-type specific shift in glutamatergic inputs to accumbal medium spiny neurons. Our data indicate a close association between accumbal GSH levels and individuals capacity to exert reward-incentivized effort over time. They also suggest that improvement of accumbal antioxidant function may be a feasible approach to boost motivation.

neuroscience↗

bioRxiv2018

Profound functional and molecular diversity of mitochondria revealed by cell type-specific profiling in vivo

Mitochondria vary in morphology and function in different tissues, however little is known about their molecular diversity among cell types. To investigate mitochondrial diversity in vivo, we developed an efficient protocol to isolate cell type-specific mitochondria based on a new MitoTag mouse. We profiled the mitochondrial proteome of three major neural cell types in cerebellum and identified a substantial number of differential mitochondrial markers for these cell types in mice and humans. Based on predictions from these proteomes, we demonstrate that astrocytic mitochondria metabolize long-chain fatty acids more efficiently than neurons. Moreover, we identified Rmdn3 as a major determinant of ER-mitochondria proximity in Purkinje cells. Our novel approach enables exploring mitochondrial diversity on the functional and molecular level in many in vivo contexts.

cell biology↗