Biology subjects

Moechars, D.

Publications and source records attributed to Moechars, D..

6 recordsLinked to original sources

bioRxiv2025

Phagocytes as Plaque Catalysts: Human Macrophages Actively Generate Pathogenic Aβ42 Fibrils with Seeding and Cross-Seeding Potency

The prevailing view frames microglia and macrophages as guardians against amyloid beta (A{beta}) accumulation in Alzheimers disease (AD). Here, we overturn this paradigm by demonstrating that human phagocytic cells--including differentiated THP-1 macrophages and iPSC-derived microglia--are not merely passive responders but active producers of extracellular, seeding-competent A{beta}42 fibrils, the amyloid species most strongly linked to parenchymal plaque formation and neurodegeneration. These cell-generated aggregates differ structurally and functionally from synthetic fibrils, exhibiting heightened seeding activity and the ability to cross-seed tau aggregation, a key driver of AD progression. Notably, A{beta}42 fibril formation in this system requires active cellular processes and is exacerbated by loss of TREM2, a major AD risk gene. Transcriptomic profiling reveals an early inflammatory response resembling microglial states observed in human AD models, positioning this system as a tractable, human-relevant platform to dissect the interplay between A{beta} aggregation, innate immunity, and genetic susceptibility. Our findings suggest that macrophages and microglia play a dual role in AD, acting both as responders and inadvertent catalysts of pathogenic amyloid formation, with implications for early therapeutic intervention. Significance StatementHow amyloid plaques emerge and spread in Alzheimers disease remains a critical unanswered question. Here, we show that human immune cells--including brain-resident microglia--can actively generate A{beta}42 fibrils, the form of amyloid most strongly linked to neurodegeneration. These cell-produced fibrils not only seed further amyloid buildup but also trigger tau aggregation, a key event in disease progression. We further demonstrate that genetic risk factors like TREM2 amplify this process. Our findings reveal a direct link between immune cell activity, genetic susceptibility, and the earliest stages of Alzheimers pathology, offering new insights into disease mechanisms and potential intervention points.

biochemistry↗

bioRxiv2025

Data-independent acquisition (DIA) approach for comprehensive ubiquitinome profiling in targeted protein degradation

Targeted protein degradation (TPD) has emerged as a highly promising therapeutic strategy for a wide range of diseases, including cancer and neurodegenerative disorders. The ubiquitin-proteasome system, which is responsible for protein degradation, plays a critical role in this process. Gaining comprehensive insights into the ubiquitylation landscape is essential for the development of selective and efficient targeted protein degradation approaches. Recently, data-independent acquisition (DIA) has gained significant popularity as a robust and unbiased approach for quantitative proteomics. Here, we report a cutting-edge workflow that utilizes diGly antibody-based enrichment followed by an optimized Orbitrap-based DIA method for the identification of ubiquitylated peptides. We identify over 40,000 diGly precursors corresponding to more than 7,000 proteins in a single measurement from cells exposed to a proteasome inhibitor, highlighting an exceptional throughput. By applying our optimized workflow, we successfully identify ubiquitylation sites on substrate proteins with various TPD approaches. Therefore, our workflow holds tremendous potential for rapidly establishing mode of action for various TPD modalities, including PROTACs and molecular glues.

cell biology↗

bioRxiv2025

In vivo validation of novel non-invasive PHP.eB AAVs as a potential therapeutic approach for alpha-Synucleinopathies

Parkinsons disease (PD) is characterized by the accumulation of alpha-synuclein (aSyn) aggregates in specific brain regions, which are likely to be the disease-causing entities. Herein, we employed novel, systemically administered, brain-penetrating viral vectors (PHP.eB AAVs) in order to evaluate the potential therapeutic utility of lowering the endogenous aSyn protein burden in the aSyn pre-formed fibril (PFF)-mouse model. Such vectors expressing short hairpin RNAs or micro RNAs targeting the mouse Snca transcript (or respective scrambled control sequences) were intravenously administered in adult wild-type mice and two weeks later human aSyn PFFs were injected into the dorsal striatum. Following the administration of the Snca-targeting PHP.eB AAVs, a successful widespread viral transduction was achieved throughout the brain, accompanied by an efficient reduction of endogenous aSyn protein levels within transduced dopaminergic neurons. Intrastriatal injection of human aSyn PFFs led to the formation of pSer129-aSyn-rich cytoplasmic inclusions in brain regions connected to the PFF-injection site, nigrostriatal degeneration and relevant behavioral motor deficits, at 2.5 months post PFF-injection. Importantly, PHP.eB AAV-mediated down-regulation of endogenous aSyn reduced the accumulation of pSer129-aSyn+ inclusions, mitigated nigrostriatal degeneration and alleviated motor impairments. Spread of pathology to other brain regions was also attenuated. Overall, such data highlight further the contribution of the intracellular aSyn protein load to the spread of pathology and suggest that this non-invasive delivery strategy holds promise in the research avenues for treating neurodegenerative diseases with widespread pathology, such as Synucleinopathies.

neuroscience↗

bioRxiv2025

Targeted degradation of α-synuclein prevents PFF-induced aggregation

Accumulation of misfolded -synuclein protein in intracellular inclusion bodies of dopaminergic neurons underlies the pathogenesis of Synucleinopathies, which include Parkinsons Disease (PD), Dementia with Lewy Bodies (DLB) and Multiple System Atrophy (MSA). Therefore, clearance of misfolded -synuclein from dopaminergic neurons could in principle offer a therapeutic window for Synucleinopathies, which currently remain untreatable. In this study, we employ the Affinity-directed PROtein Missile (AdPROM) system consisting of the substrate receptor of the CUL2-E3 ligase complex VHL and a nanobody selectively recognising the human -synuclein protein and demonstrate targeted degradation of endogenous -synuclein from human cell lines with remarkable selectivity. We further demonstrate that targeted degradation of -synuclein prevents the pre-formed fibril (PFF)-induced aggregation of -synuclein in primary neurons derived from rats expressing human -synuclein. This approach represents the first demonstration of nanobody-guided proteasomal degradation of all clinically relevant -synuclein variants, highlighting its potential as a therapeutic strategy against Synucleinopathies.

neuroscience↗

bioRxiv2023

Applying high-resolution spatial transcriptomics to characterise the amyloid plaque cell niche in Alzheimer's Disease

The amyloid plaque cell niche is a pivotal hallmark of Alzheimers disease (AD). Where early spatial transcriptomics (ST) technologies have provided valuable information on transcriptomic alterations in the small tissue domains overlaying with amyloid plaques, they lacked cellular resolution. Here we compare two novel high-resolution ST platforms, CosMx and Stereo-seq, in their ability to characterize the cellular response in the amyloid plaque niche in an AD mouse model. Combining the results from both techniques empowered us to survey the highly variable microglial-astrocytic response across the amyloid plaque micro-environment and provided a first insight into how these responses could relate to neuronal transcriptomic alterations. This pilot study demonstrates the great potential of high-resolution ST, while simultaneously highlighting limitations that, when addressed, will unleash the full power of these techniques to map the progression of molecular and cellular changes in the brains of AD patients.

neuroscience↗

bioRxiv2022

Astrocyte calcium dysfunction causes early network hyperactivity in Alzheimer's Disease

Dysfunctions of network activity and functional connectivity (FC) represent early events in Alzheimers disease (AD), but the underlying mechanisms remain unclear. Astrocytes regulate neuronal activity in the healthy brain, but their involvement in early network hyperactivity in AD is unknown. We show increased FC in the human cingulate cortex, several years before amyloid deposition. We found the same early cingulate FC disruption and neuronal hyperactivity in AppNL-F mice. Crucially, these network disruptions are accompanied by decreased astrocyte calcium signaling. Recovery of astroglial calcium activity normalizes neuronal hyperactivity and FC, as well as seizure susceptibility and day/night behavioral hyperactivity. In conclusion, we show for the first time that astrocytes mediate initial features of AD and drive clinically relevant phenotypes.

neuroscience↗