Biology subjects

Shepilov, D.

Publications and source records attributed to Shepilov, D..

3 recordsLinked to original sources

bioRxiv2025

Regional patterns of neurodegeneration in a mouse model of proteinopathy

The aggregation of misfolded proteins is a hallmark of many neurodegenerative diseases, suggesting shared pathological mechanisms. However, the pathways by which protein misfolding in these proteinopathies lead to neuronal death remain unclear. Proteinopathies can be modelled in transgenic animals by expressing disease-causing mutations that promote protein aggregation, or in wild-type animals by injecting misfolded proteins (e.g. RML scrapie) that spread in a prion-like manner and recapitulate key neurodegenerative features, including gliosis, ER stress, and neuronal loss. Here, we map region-specific histopathological features of scrapie-induced neurodegeneration in the hippocampus, thalamus, cortex, and cerebellum during early (12 weeks post-inoculation) and late (20 weeks) stages of disease. Using a streamlined time-efficient protocol, we achieve reproducible paired sample collection and high-quality immunohistochemistry that is compatible with best practice in decontamination and containment. We found that among the tested markers of early pathology, thalamic astrocytic activation and spongiform degeneration were the most sensitive. By the late stage, there was widespread upregulation of IBA1+ microglia and GFAP+ astrocytes, accompanied by strong immunoreactivity of lysosomal marker LAMP1. LAMP1 expression in healthy brains was largely neuronal, but by 20 weeks it was significantly upregulated in astrocytes, suggesting their involvement in lysosomal pathology. The ER stress marker p-PERK was elevated in CA1/CA3 pyramidal neurons but minimal in the thalamus and cerebellum, where neuronal loss was most pronounced, suggesting region-specific mechanisms of degeneration. Overall, the thalamus and hippocampal CA1/CA3 areas exhibited the greatest pathological burden. Our shorter time-course, new pathological insights and safe handling protocols, and improved welfare, supports broader adoption of the RML scrapie model for resource-efficient studies of neurodegeneration and its prevention.

neuroscience↗

bioRxiv2024

Unbiased preclinical phenotyping reveals neuroprotective properties of pioglitazone

Animal models are essential for assessing the preclinical efficacy of candidate drugs, but animal data often fails to replicate in human clinical trials. This translational gulf is due in part to the use of models that do not accurately replicate human disease processes and phenotyping strategies that do not capture sensitive, disease-relevant measures. To address these challenges with the aim of validating candidate neuroprotective drugs, we combined a mouse prion (RML scrapie) model that recapitulates the key common features of human neurodegenerative disease including bona fide neuronal loss, with unbiased and machine learning-assisted behavioural phenotyping. We found that this approach measured subtle, stereotyped, and progressive changes in motor behaviour over the disease time course that correlated with the earliest detectable histopathological changes in the mouse brain. To validate the utility of this model system, we tested whether the anti-diabetic drug pioglitazone could slow prion disease progression. Pioglitazone crosses the blood-brain-barrier and has been shown to reduce neurodegenerative disease severity in other mouse models. We found that in addition to significantly slowing the emergence of early-stage clinical signs of neurodegeneration, pioglitazone significantly improved motor coordination throughout the disease time course and reduced neuronal endoplasmic reticulum stress. Together, these findings suggest that pioglitazone could have neuroprotective properties in humans, confirm the utility of the scrapie mouse model of neurodegeneration, and provide generalisable experimental and analysis methods for the generation of data-rich behavioural data to accelerate and improve preclinical validation.

neuroscience↗

bioRxiv2024

GLP1R agonists activate human POMC neurons

Drugs like semaglutide (a.k.a. Ozempic/Wegovy) that activate the glucagon-like peptide-1 receptor (GLP-1R) are a promising therapy for obesity and type 2 diabetes (T2D). Animal studies suggest that these drugs likely function by stimulating GLP-1R on appetite-suppressing neuron populations in the brain, but it is still unclear how they act to reduce food intake in humans. We therefore generated appetite-regulatory hypothalamic neurons from human pluripotent stem cells (hPSCs) to study their responses to GLP-1R agonists by calcium imaging and electrophysiology. We found that hPSC-derived proopiomelanocortin (POMC) and other hypothalamic neuron subtypes expressed GLP1R mRNA, and many of these neurons robustly responded to GLP-1R agonists by membrane depolarization, increased action potential firing, and extracellular calcium influx that persisted long after agonist withdrawal. The observed GLP-1R-induced response was likely mediated by the activation of PKA and L-type calcium channels, and led to significant changes in gene expression. These findings provide mechanistic insight into how GLP-1R agonists may suppress appetite in humans.

neuroscience↗