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Results for “Pathology”

Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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At least 163 records · Page 9Linked to original sources

bioRxiv2024

Autoimmune antibody-induced neuronal hyperactivity triggers pathological Tau in IgLON5 disease

Anti-IgLON5 disease is an autoimmune disease, in which autoantibodies (AABs) against the neuronal cell surface protein IgLON5 lead to profound brain dysfunction and Tau pathology. How -IgLON5 AABs cause neuronal Tau protein pathology and neurodegeneration remains unclear. We find that patient-derived -IgLON5 AABs cluster IgLON5 proteins with other cell surface proteins, leading to neuronal hyperactivity that triggers pathological Tau missorting and phosphorylation, typically observed early in Tau-related neurodegenerative diseases. In wildtype mice, -IgLON5 AABs induce hippocampal Tau phosphorylation and neuroinflammatory responses. Our findings establish a causal link between the -IgLON5 AABs and Tau pathology in anti-IgLON5 disease patients, and highlight the role of neuronal hyperactivity as a disease-overarching driver of Tau pathology and provide a potential target for therapeutic intervention. Teaser-IgLON5 autoantibodies induce clustering of neuronal cell surface proteins, leading to acute neuronal hyperactivity and Tau missorting.

neuroscience↗

bioRxiv2024

Virus-like particle (VLP)-based vaccine targeting tau phosphorylated at Ser396/Ser404 (PHF1) site outperforms phosphorylated S199/S202 (AT8) site in reducing tau pathology and restoring cognitive deficits in the rTg4510 mouse model of tauopathy.

Tauopathies, including Alzheimers disease (AD) and Frontotemporal Dementia (FTD), are histopathologically defined by the aggregation of hyperphosphorylated pathological tau (pTau) as neurofibrillary tangles in the brain. Site-specific phosphorylation of tau occurs early in the disease process and correlates with progressive cognitive decline, thus serving as targetable pathological epitopes for immunotherapeutic development. Previously, we developed a vaccine (Q{beta}-pT181) displaying phosphorylated Thr181 tau peptides on the surface of a Q{beta} bacteriophage virus-like particle (VLP) that induced robust antibody responses, cleared pathological tau, and rescued memory deficits in a transgenic mouse model of tauopathy. Here we report the characterization and comparison of two additional Q{beta} VLP-based vaccines targeting the dual phosphorylation sites Ser199/Ser202 (Q{beta}-AT8) and Ser396/Ser404 (Q{beta}-PHF1). Both Q{beta}-AT8 and Q{beta}-PHF1 vaccines elicited high-titer antibody responses against their pTau epitopes. However, only Q{beta}-PHF1 rescued cognitive deficits, reduced soluble and insoluble pathological tau, and reactive microgliosis in a 4-month rTg4510 model of FTD. Both sera from Q{beta}-AT8 and Q{beta}-PHF1 vaccinated mice were specifically reactive to tau pathology in human AD post-mortem brain sections. These studies further support the use of VLP-based immunotherapies to target pTau in AD and related tauopathies and provide potential insight into the clinical efficacy of various pTau epitopes in the development of immunotherapeutics.

neuroscience↗

bioRxiv2024

Aquaporin-4 mis-localization slows glymphatic clearance of α-synuclein and promotes α-synuclein pathology and aggregate propagation

The appearance of misfolded and aggregated proteins is a pathological hallmark of numerous neurodegenerative diseases including Alzheimers disease and Parkinsons disease. Sleep disruption is proposed to contribute to these pathological processes and is a common early feature among neurodegenerative disorders. Synucleinopathies are a subclass of neurodegenerative conditions defined by the presence of -synuclein aggregates, which may not only enhance cell death, but also contribute to disease progression by seeding the formation of additional aggregates in neighboring cells. The mechanisms driving intercellular transmission of aggregates remains unclear. We propose that disruption of sleep-active glymphatic function, caused by loss of precise perivascular AQP4 localization, inhibits -synuclein clearance and facilitates -synuclein propagation and seeding. We examined human post-mortem frontal cortex and found that neocortical -synuclein pathology was associated with AQP4 mis-localization throughout the gray matter. Using a transgenic mouse model lacking the adapter protein -syntrophin, we observed that loss of perivascular AQP4 localization impairs the glymphatic clearance of -synuclein from intersititial to cerebrospinal fluid. Using a mouse model of -synuclein propogation, using pre-formed fibril injection, we observed that loss of perivascular AQP4 localization increased -synuclein aggregates. Our results indicate -synuclein clearance and propagation are mediated by glymphatic function and that AQP4 mis-localization observed in the presence of human synucleinopathy may contribute to the development and propagation of Lewy body pathology in conditions such as Lewy Body Dementia and Parkinsons disease. SummaryIn a human postmortem case series, we observe that neocortical Lewy body pathology is associated with mis-localization of the astroglial water channel aquaporin-4 (AQP4). In mice, -synuclein is cleared from the brain along perivascular pathways, while loss of perivascular AQP4 localization impairs glymphatic -synuclein clearance to the CSF. Furthermore, loss of perivascular AQP4 localization promotes the development and propagation of -synuclein aggregates.

neuroscience↗

bioRxiv2024

Reduction of RAD23A extends lifespan and mitigates pathology in TDP-43 mice

Protein misfolding and aggregation are cardinal features of neurodegenerative disease (NDD) and they contribute to pathophysiology by both loss-of-function (LOF) and gain-of-function (GOF) mechanisms. This is well exemplified by TDP-43 which aggregates and mislocalizes in several NDDs. The depletion of nuclear TDP-43 leads to reduction in its normal function in RNA metabolism and the cytoplasmic accumulation of TDP-43 leads to aberrant protein homeostasis. A modifier screen found that loss of rad23 suppressed TDP-43 pathology in invertebrate and tissue culture models. Here we show in a mouse model of TDP-43 pathology that genetic or antisense oligonucleotide (ASO)-mediated reduction in rad23a confers benefits on survival and behavior, histological hallmarks of disease and reduction of mislocalized and aggregated TDP-43. This results in improved function of the ubiquitin-proteasome system (UPS) and correction of transcriptomic alterations evoked by pathologic TDP-43. RAD23A-dependent remodeling of the insoluble proteome appears to be a key event driving pathology in this model. As TDP-43 pathology is prevalent in both familial and sporadic NDD, targeting RAD23A may have therapeutic potential.

neuroscience↗

bioRxiv2024

Proteostasis dysregulation in p.A53T-α-Synuclein iPSC-derived astrocytes exacerbates neurodegeneration in a Parkinson's disease model with Lewy-like pathology

Alpha-Synuclein (Syn) plays a central role in Parkinsons disease (PD) and the p.A53T mutation causes an early-onset familial form of PD with severe manifestations. The pathological effects of the p.A53T-Syn mutation have been extensively investigated in neurons, yet the consequences on astrocytes and astrocytic contribution to PD pathology are understudied. Here, we differentiated induced pluripotent stem cells from PD patients carrying the p.A53T-Syn mutation to astrocytes, which uncovered cell-intrinsic phenotypes, including calcium dyshomeostasis and accumulation of protein aggregates. Proteomic profiling and functional analyses revealed perturbed protein catabolic processes, involving the proteasome and autophagy, associated with lysosomal malfunction. Dopamine neurons co-cultured with p.A53T-Syn astrocytes displayed exacerbated neurodegeneration with hallmark Lewy-like pathologies, reversed by control astrocytes at least due to their ability to resolve neuronal Syn aggregates by endocytic clearance. Our findings underscore a critical impact of p.A53T-Syn on astrocytic protein quality control mechanisms, positioning astrocytes as important contributors to PD neuropathology. HighlightsO_LIiPSC-derived astrocytes from PD patients with the p.A53T-Syn mutation display cell-autonomous pathological phenotypes and toxic Syn accumulation C_LIO_LIProteome and functional analyses reveal failure of major proteostasis mechanisms in p.A53T-Syn astrocytes, largely related to lysosomal malfunction C_LIO_LIInherent Lewy-like pathological features are identified in p.A53T-Syn astrocyte-neuron co-cultures C_LIO_LIp.A53T-Syn astrocytes induce PD-relevant neuropathology to healthy neurons C_LIO_LIControl but not p.A53T-Syn astrocytes alleviate neuropathology in co-cultured neurons C_LI

neuroscience↗

bioRxiv2024

Quantifying Pathological Progression from Single-Cell Data

The surge in single-cell datasets and reference atlases has enabled the comparison of cell states across conditions, yet a gap persists in quantifying pathological shifts from healthy cell states. To address this gap, we introduce single-cell Pathological Shift Scoring (scPSS) which provides a statistical measure for how much a "query" cell from a diseased sample has been shifted away from a reference group of healthy cells. In scPSS, The distance of a query cell to its k-th nearest reference cell is considered as its pathological shift score. Euclidean distances in the top n principal component space of the gene expressions are used to measure distances between cells. The p-value of a query pathological shift score belonging to the null distribution of intra-reference cell shift scores provides a statistical significance measure of the query cell being in the reference cell group. This makes our method both simple and statistically rigorous. Comparative evaluations against a state-of-the-art contrastive variational inference model, modified for shift scores, demonstrate our methods accuracy and efficiency. Additionally, we have also shown that the aggregation of cell-level pathological scores from scPSS can be used to predict health conditions at the individual level.

genomics↗

bioRxiv2024

Dissecting the differential role of C-terminal truncations in the regulation of aSyn pathology formation and the biogenesis of Lewy bodies

Alpha-synuclein (aSyn) post-translational modifications (PTMs), particularly phosphorylation at serine 129 and C-terminal truncations, are highly enriched in Lewy bodies (LBs), Lewy neurites, and other types of aSyn pathological aggregates in the brain of patients with Parkinsons disease (PD) and other synucleinopathies. However, our knowledge about the precise role of PTMs in regulating the different stages of pathology formation, neurodegeneration, and aSyn pathology spreading remains incomplete. In this work, we applied a systematic approach to address this knowledge gap with an emphasis on mapping and elucidating the role of post-fibrillization C-terminal aSyn truncations in regulating the uptake, processing, seeding activity, and formation of LB-like inclusions and maturations in a well-established neuronal seeding model that recapitulates all the stages leading to LB formation and neurodegeneration. Our work shows that C-terminal cleavage of aSyn fibrils at multiple sites is a conserved process that occurs rapidly after and during the formation of intracellular LB-like aSyn inclusions in all neuronal seeding models. Interestingly, blocking the cleavage of internalized fibrils does not influence their seeding activity, whereas inhibiting the enzymes that regulate the cleavage of newly formed fibrils (e.g., calpains 1 and 2) significantly alters the formation of LB-like inclusions. We also show that C-terminal truncations, in combination with other PTMs, play a crucial role in regulating the interactome and remodeling of newly formed aSyn fibrils, including their shortening, lateral association, and packing during LB formation and maturation. Altogether, our results demonstrate that post-fibrillization C-terminal truncations have a differential role at different stages of aSyn aggregation and pathology formation. These insights, combined with the abundance of truncated aSyn species in LBs, have significant implications in understanding aSyn pathological diversity and developing therapeutic strategies targeting the C-terminus of aSyn or its proteolytic processing.

neuroscience↗

bioRxiv2025

An MRI-informed histo-molecular analysis implicates ependymal cells in the pathogenesis of periventricular pathology in multiple sclerosis

It is now widely recognized that the cerebrospinal fluid (CSF)-adjacent brain surfaces - namely the subpial cortical region and the ependyma-adjacent periventricular region - are uniquely susceptible to a distinct, diffuse form of pathology in multiple sclerosis. So-called surface-in gradients of pathology predict future disease relapses independent of classical white matter lesions and are thought to occur as a result of cytotoxic factors in the CSF. Given the underlying mechanisms driving surface-in gradients appear to be distinct, they represent a novel treatment target. However, exactly how cytotoxic factor entry into the brain is regulated at these CSF-facing borders is not understood, particularly at the ventricular interface. Indeed, although studies have indicated that ependymal cells may be damaged in MS, there has yet to be a comprehensive assessment of cell health in the disease. We employed ultra-high-field MRI-guided immunohistochemistry, electron microscopy, and multiomic single nucleus RNA/ATAC sequencing to deeply phenotype human ependymal cells in MS. Our data revealed that ependymal cell pathology is a direct correlate of periventricular surface-in gradients of pathology in MS, and that the immune-responsive, reactive state assumed by ependymal cells is associated with widespread transporter and junctional protein gene dysregulation. We then further defined the gene regulatory networks underpinning the MS ependymal state, predicted ligands known to be enriched in MS CSF that could drive the emergence of this state, and tested one candidate in vivo. We found that IFN{gamma} increased murine ependymal permeability and that conditional knockout of ependymal interferon gamma receptor 1 (Ifngr1) was sufficient to reverse this effect. Our data directly implicate ependymal cell dysregulation in the emergence of periventricular pathology in MS. More widely, we denote the modulatory capacity of CSF ligands on ependymal cell function and how this may influence the inflammatory status of the periventricular region. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=146 SRC="FIGDIR/small/633055v2_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@d76aadorg.highwire.dtl.DTLVardef@9cb480org.highwire.dtl.DTLVardef@e4805org.highwire.dtl.DTLVardef@19a50b4_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Repeated blood-brain barrier opening using low-intensity pulsed ultrasound mitigates amyloid pathology

BackgroundThe delivery of large molecules to the pathological brain is one of the main obstacles in the development of disease-modifying drugs. This is partly due to the presence of the blood-brain barrier (BBB), which blocks the free passage of lipophobic molecules and those larger than 400 Da. One strategy to bypass this natural barrier is to use low intensity pulsed ultrasound (LIPU) to oscillate circulating micro-sized microbubbles which then exert mechanical stress on the vessel walls. This procedure allows for temporary disruption of the BBB and enhanced local delivery of therapeutics from the blood to the brain parenchyma. In this study, the effect of repeated BBB opening on neuroinflammation in a healthy mouse model was first explored followed by the effect of repeated opening on amyloid pathology in a model for Alzheimers disease. MethodsA cohort of wildtype mice was used to determine the effect of a single BBB opening session mediated by ultrasound/microbubbles (US/MB) on the inflammatory profile, using RT-Q-PCR on brain extracts at 2-, 4-, 8- and 15-days post opening. A second cohort of ARTE10 mice, a mouse model for amyloid pathology, was treated with a different sequence of repeated US/MB mediated BBB opening to explore the effect on the pathology. Tissues were also analyzed for immune cell infiltration, microglia and astrocyte activation, and inflammatory response. ResultsOur results demonstrate that the opening of the BBB leads to a mild inflammatory response in wild-type animals. However, repeated opening of the BBB in the ARTE10 model resulted in a mild decrease in amyloid pathology, along with a mild increase of growth factor. ConclusionsAltogether, this study suggests that sonication is not only a safe method to deliver therapeutics to the brain but could also have synergistic effects in the treatment of neurodegenerative diseases.

neuroscience↗

bioRxiv2025

Tau pathology reprograms glucose metabolism to support glutamatergic activity and excitatory imbalance

Alzheimers disease (AD) is not only characterized by amyloid-beta (A{beta}) and tau pathology, but also by early and progressive disruptions in metabolism. Neuronal excitability is tightly coupled with metabolic demand, and aberrant excitatory activity - observed in AD patients and models - can drive changes in metabolism. While A{beta}-related metabolic impairments are well-described, less is known about how tau pathology independently contributes to altered metabolic states and excitatory tone. Therefore, we explored how tau pathology impacted whole body and CNS metabolism in mouse models of tauopathy, including the P301S PS19 and Tau4RTg2652 mice. In both models, hyperphosphorylated tau prevents the age-related decline in whole-body metabolism by preserving glucose tolerance and mitigating shifts in fuel utilization (respiratory exchange ratio; RER), suggesting the mice are "glucose needy". Tau pathology also preserves diurnal rhythms in hippocampal interstitial fluid (ISF) glucose and lactate, likely due to increased neuronal activity during the active (dark) phase. Stable isotope-resolved metabolomics following 13C-glucose administration revealed that glucose is preferentially shunted toward glutamate synthesis--at the expense of GABA--highlighting a shift in excitatory/inhibitory balance. Interestingly, these changes were not explained by a primary deficit in synaptic mitochondria but by alterations in glycolytic flux. Adaptations were time of day dependent, where ISF glutamate rises after a glucose injection in the dark period but not the light period. This suggests increased glutamatergic activity may drive metabolic demand during the dark period when mice are more active. Together, these studies fundamentally highlight the important coupling between metabolism and excitability, which is disrupted by hyperphosphorylated tau, tau aggregation, and neurodegeneration. Understanding how tau pathology and metabolism interrelate provides a novel lens for the development of therapeutic targets in late stage AD.

neuroscience↗

bioRxiv2025

Helicobacter pylori infection and α-synuclein pathology drive parallel neurodegenerative pathways in the substantia nigra

Parkinsons disease is a common neurodegenerative disease related to both genetic and environmental insults. Epidemiological studies have linked Helicobacter pylori (H. pylori) infection to Parkinsons disease risk, but the underlying mechanisms of this association remain unclear. In this study, we investigate whether chronic infection with a pathogenic H. pylori strain can induce -synuclein aggregation or neurodegeneration, and whether infection clearance mitigates these effects. We also assessed whether H. pylori infection exacerbates -synuclein pathology and neuron loss when combined with seeding of -synuclein pathology. We find that chronic H. pylori infection induces a sustained immune response in the gut and plasma that leads to mild brain inflammation and dopaminergic neuron loss, independent of -synuclein pathology. These effects are attenuated by eradication of the infection. In mice with -synuclein pathology induced by pre-formed fibrils, H. pylori did not further exacerbate the extent of pathology or neuronal death. Together, these results suggest that H. pylori infection can lead to neurodegeneration through inflammatory mechanisms independent of -synuclein aggregation. Our findings offer mechanistic insights into how pathogens influence the risk and progression of Parkinsons disease.

neuroscience↗

bioRxiv2025

An Autophagy-Inducing Compound Reduces Tau Pathology, Microglia Reactivity, and Rescues Working Memory in 3xTg AD Mice

BackgroundRecent advancements in Alzheimers disease (AD) therapeutics have validated the use of amyloid beta (A{beta})-clearing antibodies, which reduce A{beta} pathology but leave other disease hallmarks largely unaddressed. Since AD involves multiple pathological processes, additional strategies are needed to target complementary mechanisms. One such target is autophagy, a lysosomal mediated degradation pathway essential for cellular homeostasis that removes toxic protein aggregates and damaged organelles. This process is implicated in AD, as impaired lysosomal function promotes A{beta} and tau accumulation. Our laboratory recently identified a novel natural mitophagy-inducing compound (MIC) that may serve as a therapeutic intervention for AD. MethodsWe evaluated the effects of MIC in aged 3xTgAD mice, a transgenic model displaying both A{beta} and tau pathology. Mice received either standard diet or diet containing MIC beginning at age 4 months until 20 months on alternating weeks. Age-matched non-transgenic (NonTg) controls were included under standard and MIC-supplemented diets to assess compound effects during normal aging. Neuropathological changes were assessed using immunohistochemistry (IHC) for A{beta}, phosphorylated tau (pTau), and microglial reactivity. Cognitive performance was evaluated using the Morris Water Maze (MWM) to assess spatial learning and memory and the Y-maze to measure working memory. ResultsAt 20 months of age, our neuropathological assessment showed that 3xTgAD mice fed an MIC-supplemented diet had a significant reduction in pTau accumulation and microglial reactivity, although A{beta} burden remained unchanged. At 15 months, MIC diet also improved spatial learning and memory in aged NonTg controls but not in 3xTgAD mice. However, in younger 8-month-old 3xTgAD mice, MIC restored working memory performance to NonTg levels, indicating an age-dependent therapeutic response. ConclusionMIC emerges as a potential modulator of tau pathology and neuroinflammation. As a naturally derived compound, MIC offers potential for combination therapy with FDA-approved A{beta}-clearing antibodies, enabling a multimodal approach to AD treatment that addresses amyloid, tau, and microglia-related pathology.

neuroscience↗

bioRxiv2018

Tau seeding activity anticipates phospho-tau pathology in Alzheimer’s disease

Alzheimers disease (AD) is characterized by accumulation of tau neurofibrillary tangles (NFTs) and, according to the prion model, transcellular propagation of pathological \"seeds\" may underlie its progression. Staging of NFT pathology with phospho-tau antibody is useful to classify AD and primary age-related tauopathy (PART) cases. The locus coeruleus (LC) shows the earliest phospho-tau signal, whereas other studies suggest that pathology begins in the transentorhinal/entorhinal cortices (TRE/EC). The relationship of tau seeding activity, phospho-tau pathology, and progression of neurodegeneration remains obscure. Consequently, we employed an established cellular biosensor assay to quantify tau seeding activity in fixed human tissue, in parallel with AT8 phospho-tau staining of immediately adjacent sections. We studied four brain regions from each of n=247 individuals across a range of disease stages. We detected the earliest and most robust seeding activity in the TRE/EC. The LC did not uniformly exhibit seeding activity until later NFT stages. We also detected seeding activity in the first temporal gyrus and visual cortex at stages before NFTs and/or AT8-immunopositivity were detectable. AD and putative PART cases exhibited similar patterns of seeding activity that anticipated histopathology across all NFT stages. Our findings are consistent with the prion model and suggest that pathological seeding activity begins in the TRE/EC rather than in the LC, and may offer an important addition to classical histopathology.

neuroscience↗

bioRxiv2018

Patterns of reduced cortical thickness and striatum pathological morphology in cocaine addiction.

Substance addiction is regarded as an important public health problem, perpetuated by fronto-striatal circuit pathology. A usual finding in neuroimaging human and murine studies is cortical thinning and lower volume when compared to healthy controls. In this study we wished to replicate cortical thinning findings and find if striatum morphology may explain the cortical pathology. For this we analyzed T1w neuroimaging data from an ongoing addiction Mexican dataset. This dataset includes cocaine addicts diagnosed by expert psychiatrists and healthy controls. For the analysis we used voxel-based morphometry, cortical thickness and volumetric analysis of the basal ganglia, and we correlated striatum volume with cortical thickness to find pathological patterns. Our group contrast showed cortical thinning and striatum volume differences in cocaine addicts correlated to their years of substance use, craving and age. Our correlation between striatum-cortex morphology showed higher significant correlations in healthy controls, not observed in cocaine addicts. The correlation between striatum volume and cortical thickness in healthy controls involved similar areas as those shown with less cortical thickness in cocaine addicts. We suggest that striatum morphological changes in addiction may explain the pattern of cortical thinning observed across several substances addiction studies.\n\nResearch Data Related to this SubmissionData set https://zenodo.org/record/1409808#.W5E3oCOZPIF Patterns of reduced cortical thickness and striatum pathological morphology in cocaine addiction\n\nThis dataset includes all the data and scripts needed to reproduce the analysis and results on the manuscript \"Patterns of reduced cortical thickness and striatum pathological morphology in cocaine addiction\" (link). The brain data is not raw, as T1w were not defaced. We will do so in the near future for version 2.0. Instead we include only the \"output/thickness\" files used in the final analysis. For the use of raw T1w images, please contact the main author EAGV.

neuroscience↗

bioRxiv2018

A multiscale model of epigenetic heterogeneity reveals the kinetic routes of pathological cell fate reprogramming

The inherent capacity of somatic cells to switch their phenotypic status in response to damage stimuli in vivo might have a pivotal role in ageing and cancer. However, how the entry-exit mechanisms of phenotype reprogramming are established remains poorly understood. In an attempt to elucidate such mechanisms, we herein introduce a stochastic model of combined epigenetic regulation (ER)-gene regulatory network (GRN) to study the plastic phenotypic behaviours driven by ER heterogeneity. Furthermore, based on the existence of multiple scales, we formulate a method for stochastic model reduction, from which we derive an efficient hybrid simulation scheme that allows us to deal with such complex systems. Our analysis of the coupled system reveals a regime of tristability in which pluripotent stem-like and differentiated steady-states coexist with a third indecisive state. Crucially, ER heterogeneity of differentiation genes is for the most part responsible for conferring abnormal robustness to pluripotent stem-like states. We then formulate epigenetic heterogeneity-based strategies capable of unlocking and facilitating the transit from differentiation-refractory (pluripotent stem-like) to differentiation-primed epistates. The application of the hybrid numerical method validated the likelihood of such switching involving solely kinetic changes in epigenetic factors. Our results suggest that epigenetic heterogeneity regulates the mechanisms and kinetics of phenotypic robustness of cell fate reprogramming. The occurrence of tunable switches capable of modifying the nature of cell fate reprogramming from pathological to physiological might pave the way for new therapeutic strategies to regulate reparative reprogramming in ageing and cancer.\n\nAuthor summaryCertain modifications of the structure and functioning of the protein/DNA complex called chromatin can allow adult, fully differentiated cells to adopt a stem cell-like pluripotent state in a purely epigenetic manner, not involving changes in the underlying DNA sequence. Such reprogramming-like phenomena may constitute an innate reparative route through which human tissues respond to injury and could also serve as a novel regenerative strategy in human pathological situations in which tissue or organ repair is impaired. However, it should be noted that in vivo reprogramming would be capable of maintaining tissue homeostasis provided the acquisition of pluripotency features is strictly transient and accompanied by an accurate replenishment of the specific cell types being lost. Crucially, an excessive reprogramming to pluripotency in the absence of controlled re-differentiation would impair the repair or the replacement of damaged cells, thereby promoting pathological alterations of cell fate. A mechanistic understanding of how the degree of chromatin plasticity dictates the reparative versus pathological behaviour of in vivo reprogramming to rejuvenate aged tissues while preventing tumorigenesis is urgently needed, including especially the intrinsic epigenetic heterogeneity of the tissue resident cells being reprogrammed. We here introduce a novel method that mathematically captures how epigenetic heterogeneity is actually the driving force that governs the routes and kinetics to entry into and exit from a pathological pluripotent-like state. Moreover, our approach computationally validates the likelihood of unlocking chronic, unrestrained pluripotent states and drive their differentiation down the correct path by solely manipulating the intensity and direction of few epigenetic control switches. Our approach could inspire new therapeutic approaches based on in vivo cell reprogramming for efficient tissue regeneration and rejuvenation and cancer treatment.

systems biology↗

bioRxiv2018

Chronic corticosterone enhancement aggravates alpha-synuclein brain spreading pathology and substantia nigra neurodegeneration in mice

Chronic stress and associated heightened glucocorticoid levels are risk factors for depression, a common non-motor symptom in Parkinsons disease (PD). However, how heightened glucocorticoids influence PD neuropathology [alpha-synuclein (-Syn) containing Lewy pathology and neurodegeneration] and disease progression is unclear. To address this knowledge gap, we investigated the impact of chronic corticosterone administration on -Syn pathology, neurodegeneration, behavior and mitochondrial function in a mouse model of -Syn pathology spreading after intracerebral injection of -Syn preformed fibrils (PFFs). Our results demonstrate that heightened corticosterone aggravates neurodegeneration and -Syn pathology spreading, intriguingly to specific brain regions, such as the entorhinal cortex. Corticosterone-treatment abolished distinct physiological adaptations after PFF-injection and induced differential physiological and behavioral consequences. Taken together, our work points to elevated glucocorticoids as a risk factor for the development of the neuropathological hallmarks of PD. Strategies aimed at reducing glucocorticoid levels might slow down pathology spreading and disease progression in synucleinopathy.

neuroscience↗

bioRxiv2019

Characterization of pathology-inducing α-synuclein species from human diseased brain tissue

Synucleinopathies are a group of neurodegenerative diseases characterized by the presence of pathological accumulations of misfolded, phosphorylated -synuclein (Syn) protein. Multiple lines of evidence indicate that synucleinopathy disease progression is driven by a prion-like process of transmission of a pathologic form of Syn. One potential therapeutic approach to prevent cell-to-cell propagation is to target this transmissible species with selective antibodies. In this study, a rodent primary neuronal culture reporter system was developed to monitor induction of detergent-insoluble, phosphorylated (pS129) aggregates of Syn. Induction of pS129 Syn pathology was observed with both synthetic Syn fibrils (PFFs) and brain lysates from multiple system atrophy (MSA) patients but not Syn monomers or human brain lysate controls. The induction-competent species in MSA lysates could be enriched by high-speed centrifugation suggesting that it is present as a high molecular weight aggregate. Furthermore, samples derived from brain lysates from Parkinsons disease (PD) and Dementia with Lewy Bodies (DLB) patients also induced pS129 Syn pathology, but required longer incubation times. Lastly, the potential of Syn selective antibodies to immunodeplete induction-competent forms of Syn from both PFF and synucleinopathy brain samples is described. The results demonstrate that antibodies targeting the C-terminal of Syn are most effective for immunodepletion of pathology-inducing forms of Syn from samples derived from human synucleinopathy brains. Furthermore, the data support the hypothesis that antibodies that recognize a C-terminal epitope and exhibit selectivity for oligomeric forms over monomeric forms of Syn represent a desirable target for immunotherapy for synucleinopathy patients.

neuroscience↗

bioRxiv2019

Pathological Tau Induces Neurodegeneration by Sequestering and Inhibiting LSD1

Tauopathies are a class of neurodegenerative diseases associated with pathological tau. Despite many advances in our understanding of these diseases, the direct mechanism through which tau contributes to neurodegeneration remains poorly understood. Previously, our lab implicated the histone demethylase LSD1 in tau-induced neurodegeneration by showing that LSD1 localizes to pathological tau aggregates in Alzheimers disease cases, and that it is continuously required for the survival of hippocampal and cortical neurons in mice. Here, we utilize the P301S tauopathy mouse model to demonstrate that pathological tau can exclude LSD1 from the nucleus in neurons. In addition, we show that reducing LSD1 in these mice is sufficient to highly exacerbate tau-mediated neurodegeneration and tau-induced gene expression changes. Finally, we find that overexpressing LSD1 in the hippocampus of tauopathy mice, even after pathology has formed, is sufficient to significantly delay neurodegeneration and counteract tau-induced expression changes. These results suggest that inhibiting LSD1 via sequestration contributes to tau-mediated neurodegeneration. Thus, LSD1 is a promising therapeutic target for tauopathies such as Alzheimers disease. SIGNIFICANCE STATEMENTWe have made the novel discovery that pathological tau functions through the histone demethylase LSD1 in the Alzheimers disease pathway. Thus, we have identified a mechanism that links tau to the downstream neuronal dysfunction pathways. This step can potentially be targeted therapeutically, after the onset of dementia symptoms, to block the progression of dementia in Alzheimers disease patients.

neuroscience↗