Biology subjects

Maciel, P.

Publications and source records attributed to Maciel, P..

10 recordsLinked to original sources

bioRxiv2026

PRO-FitS: a novel phenotypic assay to identify enhancers of proteostasis in C. elegans

The prevalence of neurodegenerative diseases (NDs) continues to rise with the aging of populations worldwide, representing a pressing need for the establishment of therapeutic strategies. Maintaining proteostasis is crucial for healthy aging, as the accumulation of misfolded and aggregated proteins is a key contributor to age-related cellular dysfunction and disease. This study introduces a novel phenotypic assay using Caenorhabditis elegans to screen for small molecule enhancers of proteostasis, aiming at mitigating the proteotoxic stress associated with NDs. This new methodology- PRO-FitS- uses C. elegans motor activity as a proxy for the PROteome Fitness State upon a noxious protein-denaturating stimulus, while allowing a fast and experimenter-free readout. We demonstrate the efficacy of the assay by validating the role of pharmacological mTOR inhibition and serotonergic signaling activation in reducing heat shock-induced proteotoxic damage at the whole-organism level. PRO-FitS will allow the identification of novel compounds that alleviate protein aggregation disorders, potentially revealing new pathways and cellular targets not previously implicated in proteotoxicity. Significance StatementNeurodegenerative diseases remain without effective cures, in part due to the lack of scalable methods to identify compounds that improve proteostasis. We developed PRO-FitS, a whole-organism, automated phenotypic assay in C. elegans that uses motor activity recovery as a proxy for proteome fitness after proteotoxic stress. This platform enables rapid, unbiased screening of small molecules and genetic modifiers, bridging the gap between cellular assays and complex animal models. By demonstrating the assays robustness in both wild-type and disease-relevant contexts, we establish PRO-FitS as a versatile tool for discovering therapeutic candidates and uncovering novel pathways relevant to protein aggregation disorders.

neuroscience↗

bioRxiv2026

Understanding corticosterone fluctuations and HPA-axis regulation in a mouse model of Spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) or Machado-Joseph Disease (MJD) is a neurodegenerative disease caused by a CAG triplet expansion in the ATXN3 gene, primarily characterized by motor impairments. However, SCA3/MJD also includes mood-related comorbidities that affect both patients and their caregivers. Current treatments focus on symptom management and supportive care, as no disease-modifying therapies are available. Previously, we have demonstrated decreased glucocorticoid receptor (GR) expression in post-mortem SCA3 human and mouse brains and elevated peripheral corticosterone (CORT) levels in SCA3 mice at late disease stages. Impaired GR signaling is typically associated with hypothalamic-pituitary-adrenal (HPA) axis dysfunction, common in stress-related psychiatric diseases. Our study aimed to dissect the HPA-axis (dys)function and the effect of stress exposure on SCA3/MJD progression. Using the CMVMJD135 mouse model, we evaluated HPA-axis regulation in SCA3/MJD by measuring CORT levels throughout disease progression (6 to 34 weeks of age) under basal conditions and after acute stress. At week 35, these mice underwent a dexamethasone injection to challenge the HPA-axis, and the CORT levels were measured at different timepoints to evaluate the axis response. Additionally, we applied a 6-week chronic unpredictable stress (CUS) protocol in another cohort of mice starting at an early symptomatic stage to assess stress effects on the progression of motor impairments. Our findings indicate that serum CORT levels in SCA3 mice begin to rise between 26 to 30 weeks of age, with no impairment in the physiological response to acute stress. SCA3 mice were also able to normalize CORT levels after dexamethasone challenge, suggesting normal HPA-axis function. While CUS exposure had a transient negative impact on the motor phenotype, this effect did not persist throughout disease progression. In conclusion, stressful events, either acute or chronic, do not seem to be major determinants of disease severity in SCA3 mice.

neuroscience↗

bioRxiv2025

The 5-HT1A receptor agonist NLX-112 rescues motor swimming deficits in Spinocerebellar Ataxia type 3 mice

IntroductionSpinocerebellar ataxia 3 (SCA3) is a rare neurodegenerative disorder which causes progressive motor disturbances. There is no approved drug treatment but selective activation of serotonin 5-HT1A receptors may be a promising therapeutic strategy to attenuate ataxia symptoms. MethodsNLX-112, a highly selective 5-HT1A full agonist, was tested in the CMVMJD135 transgenic mouse model of SCA3. NLX-112 (1.25 and 5 mg/kg/day) was administered BID intraperitoneally for 14 weeks starting when the mice were 12 weeks of age, i.e., after ataxia signs had become established. The motor swimming test (MST), where mice are required to swim to a raised platform, was used to evaluate the motor behavior of SCA3 mice and their performance was compared with that of wild-type (WT) mice. ResultsBoth doses of NLX-112 were well tolerated by the SCA3 mice, as assessed by welfare parameters. In the MST, the latency of SCA3 mice to reach the platform was significantly longer than that of WT mice. However, when SCA3 mice were treated with either 1.25 or 5 mg/kg/day of NLX-112, they showed robust improvement of motor performance, with swimming latencies which were similar to those of WT mice. This effect of NLX-112 was maintained throughout the period of the study. ConclusionsThe improved motor function of SCA3 mice when treated with NLX-112 supports its investigation as a drug candidate for the treatment of ataxia and related movement disorders. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/674027v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@f0a8e1org.highwire.dtl.DTLVardef@1df4d49org.highwire.dtl.DTLVardef@14af6a2org.highwire.dtl.DTLVardef@86096b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISpinocerebellar ataxia type 3 (SCA3) is marked by progressive motor disturbances C_LIO_LITargeting the serotonergic system is a promising strategy to treat SCA3 C_LIO_LITransgenic SCA3 mice were treated with NLX-112, a selective 5-HT1A agonist C_LIO_LIChronic NLX-112 normalized performance of mice in the motor swimming test C_LIO_LINLX-112 could constitute a drug candidate for treatment of the ataxia disorders C_LI

neuroscience↗

bioRxiv2025

Efficacy of chronic 5-HT1A receptor agonism by NLX-112 in a mouse model of Spinocerebellar Ataxia type 3

BackgroundSpinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by an elongated polyglutamine (polyQ) sequence in the ataxin-3 protein. This expansion triggers neuropathological events, leading to progressive motor disturbances. Currently, no approved therapy exists for this debilitating condition, but compelling evidence suggests that targeting the serotonergic system can significantly attenuate SCA3 disease progression in animal models. ObjectiveThis study aimed to assess the effects of NLX-112, a highly selective serotonin 1A receptor (5-HT1AR) full agonist, in the CMVMJD135 transgenic mouse model of SCA3. MethodsNLX-112 (0.625 and 5 mg/kg/day) and tandospirone (a 5-HT1AR partial agonist used as a comparator; 20 and 80 mg/kg/day) were administered chronically in drinking water for 34 weeks, starting prior to symptom onset. To evaluate the effects of the drugs on SCA3 mice, motor-related behavioral tests and neuropathological techniques were employed. ResultsTreatment with the higher dose of NLX-112 led to improvements in motor coordination and balance, and slowing of symptom deterioration as the disease progressed. These beneficial effects were not achieved with tandospirone. NLX-112 treatment also elicited neuroprotective effects, reducing dopaminergic (tyrosine hydroxylase-positive) cell loss and astrocyte reactivity in the substantia nigra. ConclusionsNLX-112 treatment, started pre-symptomatically, enhanced motor function, slowed disease progression and elicited neuroprotective effects in SCA3 mice, supporting its further development as a drug candidate for treatment of ataxia and related movement disorders. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/671624v1_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@548b2corg.highwire.dtl.DTLVardef@7d2f51org.highwire.dtl.DTLVardef@ad8ee4org.highwire.dtl.DTLVardef@80213c_HPS_FORMAT_FIGEXP M_FIG C_FIG Key findingsO_LINLX-112 attenuated motor deficits of SCA3 mice, when administered chronically prior to disease onset. C_LIO_LINLX-112 reduced neuropathological biomarkers in SCA3 mice, namely by restoring dopaminergic neuron loss and decreasing astrocyte reactivity. C_LIO_LINLX-112 is a potential candidate for addressing ataxia-related deficits in SCA3 patients. C_LI

neuroscience↗

bioRxiv2025

Allosteric Modulation of Pathological Ataxin-3 Aggregation: A Path to Spinocerebellar Ataxia Type-3 Therapies

Spinocerebellar ataxia type 3 (SCA3) is a rare inherited neurodegenerative disease caused by the expansion of a polyglutamine repeat in the protease ataxin-3 (Atx3). Despite extensive knowledge of the downstream pathophysiology, no disease-modifying therapies are currently available to halt disease progression. The accumulation of protein inclusions enriched in the polyQ-expanded Atx3 in neurons suggests that inhibiting its self-assembly may yield targeted therapeutic approaches. Here it is shown that a supramolecular tweezer, CLR01, binds to a lysine residue on a positively charged surface patch of the Atx3 catalytic Josephin domain. At this site, the binding of CLR01 decreases the conformational fluctuations of the distal flexible hairpin. This results in reduced exposure of the nearby aggregation-prone region, which overlaps with the substrate ubiquitin binding site and primes Atx3 self-assembly, ultimately delaying Atx3 amyloid fibril formation and reducing the secondary nucleation rate, a process linked to fibril proliferation and toxicity. These effects translate into the reversal of synapse loss in a SCA3 cultured cortical neuron model, an improved locomotor function in a C. elegans SCA3 model, and a delay in disease onset, accompanied by reduced severity of motor symptoms in a SCA3 mouse model. This study provides critical insights into Atx3 self-assembly, revealing a novel allosteric site for designing CLR01-inspired therapies targeting pathological aggregation pathways while sparing essential functional sites. These findings emphasize that targeting allosteric sites in amyloid-forming proteins may offer unique opportunities to develop safe therapeutic strategies for various protein misfolding disorders.

biophysics↗

bioRxiv2021

MorphData: Automating the data extraction process of morphological features of microglial cells in ImageJ

Microglial cells are the first line of defense within the central nervous system, with morphological characterization being widely used to define their activation status. Most methods to evaluate microglia status are manual, and, therefore, often biased, inaccurate, and time consuming. In fact, the process to collect morphological data starts with the acquisition of photomicrographs from where images of single cells are extracted. Then, the researcher collects the morphological features that characterize each cell. However, a manual data collection process from single cells can take weeks to complete. This work describes an open-source ImageJ plugin, MorphData, which automatizes the data extraction process of morphological features of single microglial cells. The plugin collects, processes, and organizes features associated with cell complexity and ramification. In a computer with limited computing power, MorphData was able to handle 699 single cells in less than 14 minutes. The same process, if performed manually, would take almost 19 working days. Overall, MorphData significantly reduces the time taken to collect morphological data from microglial cells, which can then be used to study, understand, and characterize microglia behavior in the brain of human patients or of animal models of neurological and psychiatric diseases.

bioinformatics↗

bioRxiv2021

Cerebellar neuronal dysfunction accompanies early motor symptoms in Spinocerebellar Ataxia Type 3 and is partially alleviated upon chronic citalopram treatment

Spinocerebellar Ataxia Type 3 (SCA3) is an adult-onset, progressive ataxia. SCA3 presents with ataxia before any gross neuropathology. A feature of many cerebellar ataxias is aberrant cerebellar output that contributes to motor dysfunction. We examined whether abnormal cerebellar output was present in the CMVMJD135 SCA3 mouse model and, if so, whether it correlated with the disease onset and progression. In vivo recordings showed that the activity of deep cerebellar nuclei neurons, the main output of the cerebellum, was altered. The aberrant activity correlated with the onset of ataxia. However, although the severity of ataxia increased with age, the severity of the aberrant cerebellar output was not progressive. The abnormal cerebellar output, however, was accompanied with non-progressive abnormal activity of their upstream synaptic inputs, the Purkinje cells. In vitro recordings indicated that alterations in both intrinsic Purkinje cell pacemaking and in their synaptic inputs contributed to abnormal Purkinje cell activity. These findings implicate abnormal cerebellar physiology as an early, consistent contributor to pathophysiology in SCA3, and suggest that the aberrant cerebellar output could be an appropriate therapeutic target in SCA3. Summary StatementIn a mouse model of Spinocerebellar ataxia type 3 aberrant cerebellar physiology is apparent early in disease, before overt neuronal pathology or neuronal death.

neuroscience↗

bioRxiv2020

In vivo molecular signatures of cerebellar pathology in spinocerebellar ataxia type 3

BackgroundNo treatment exists for the most common dominantly inherited ataxia Machado-Joseph disease, or spinocerebellar ataxia type 3 (SCA3). Successful evaluation of candidate therapeutics will be facilitated by validated noninvasive biomarkers of aspects of disease pathology recapitulated by animal models. ObjectiveWe sought to identify shared neurochemical signatures in two mouse models of SCA3 that reflect aspects of the human disease pathology. MethodsCerebellar neurochemical concentrations in homozygous YACMJD84.2 (Q84/Q84) and hemizygous CMVMJD135 (Q135) mice were measured by magnetic resonance spectroscopy at 9.4 tesla. Motivated by the shared neurochemical abnormalities in the two models, we determined the levels of neurofilament medium (NFL, indicator of neuroaxonal integrity) and myelin basic protein (MBP, indicator of myelination) in cerebellar lysates from a subset of mice and from patients with SCA3. Finally, NFL and MBP levels were measured in cerebellar extracts of Q84/Q84 mice upon sustained silencing of the mutant ATXN3 gene from 6-8 weeks-of-age until death. ResultsBoth Q84/Q84 and Q135 mice displayed lower N-acetylaspartate than wild-type littermates, indicating neuroaxonal loss/dysfunction, and lower myo-inositol and total choline, indicating disturbances in phospholipid membrane metabolism and demyelination. Cerebellar NFL and MBP levels were accordingly lower in both models as well as in the cerebellar cortex of patients with SCA3 than controls. Furthermore, long-term sustained RNAi-mediated reduction of ATXN3 levels increased NFL and MBP in Q84/Q84 cerebella. ConclusionsN-acetylaspartate, myo-inositol and total choline levels in the cerebellum are candidate biomarkers of neuroaxonal and oligodendrocyte pathology in SCA3, which are reversible by reduction of mutant ATXN3 levels.

neuroscience↗

bioRxiv2019

Regulation of neuronal mRNA splicing and Tau isoform ratio by ATXN3 through deubiquitylation of splicing factors

The ubiquitylation/deubiquitylation balance in cells is maintained by deubiquitylating enzymes, including ATXN3. The precise role of this protein, mutated in spinocerebellar ataxia type 3 (SCA3), remains elusive, as few substrates for its deubiquitylating activity were identified. Here, we characterized the ubiquitome of neuronal cells lacking ATXN3, and found altered polyubiquitylation in a large proportion of proteins involved in RNA metabolism, including splicing factors. Using transcriptomic analysis and reporter minigenes we confirmed that splicing was globally altered in these cells. Among the candidate targets of ATXN3 was SRSF7 (9G8), a key regulator of MAPT (Tau) exon 10 splicing. Loss-of-function of ATXN3 led to reduced SRSF7 levels and a deregulation of MAPT exon 10 splicing, resulting in a decreased 4R/3R-Tau ratio. Similar alterations were found in cellular models of expanded polyQ ATXN3 and SCA3 patient brains, pointing to a relevant role of this mechanism in SCA3, and establishing a previously unsuspected link between two key proteins involved in different neurodegenerative disorders.

neuroscience↗

bioRxiv2018

Identification of rare de novo epigenetic variations in congenital disorders

Certain human traits such as neurodevelopmental disorders (NDs) and congenital anomalies (CAs) are believed to be primarily genetic in origin. With recent dramatic advances in genomic technologies, genome-wide surveys of cohorts of patients with ND/CAs for point mutations and structural variations have greatly advanced our understanding of their genetic etiologies1,2. However, even after whole genome sequencing (WGS), a substantial fraction of such disorders remain unexplained3. In contrast, the possibility that constitutive epigenetic variations (epivariations) might underlie such traits has not been well explored. We hypothesized that some cases of ND/CA are caused by aberrations of DNA methylation that lead to a dysregulation of normal genome function. By comparing DNA methylation profiles from 489 individuals with ND/CAs against 1,534 population controls, we identified epivariations as a frequent occurrence in the human genome. De novo epivariations were significantly enriched in cases when compared to controls. RNAseq data from population studies showed that epivariations often have an impact on gene expression comparable to loss-of-function mutations. Additionally, we detected and replicated an enrichment of rare sequence mutations overlapping CTCF binding sites close to epivariations. Thus, some epivariations occur secondary to cis-linked mutations in regulatory regions, providing a rationale for interpreting non-coding genetic variation. We propose that epivariations likely represent the causative genomic defect in 5-10% of patients with unexplained ND/CAs. This constitutes a yield comparable to CNV microarrays, and as such has significant diagnostic relevance.

genomics↗