Biology subjects

Seibler, P.

Publications and source records attributed to Seibler, P..

6 recordsLinked to original sources

bioRxiv2026

Single-cell resolution uncovers cell type-specific dysregulation in Parkin-deficient neuron-microglia co-cultures

BackgroundMutations in the E3 ubiquitin ligase Parkin (encoded by PRKN) are the most frequently known cause of recessively inherited Parkinsons disease. In addition to the loss of dopaminergic neurons, microglial activation is another pathological feature observed in Parkinsons disease. While postmortem brain samples show the end stage of the disease, neurons and glia derived from patients induced pluripotent stem cells (iPSCs) provide a model for detecting early pre-degenerative disease trajectories. However, mixed cell populations often confound these cultures, leading to heterogeneous disease phenotypes. MethodsHere, we tease apart the cell type-specific phenotypes underlying Parkin-linked Parkinsons disease by performing single-nucleus RNA sequencing in iPSC-derived co-cultures of dopaminergic neurons and microglia from PRKN mutation carriers and healthy controls. We validated our transcriptomic key findings through inflammatory cytokine profiling and live-cell calcium imaging. ResultsSingle-nucleus RNA sequencing identified seven major cell types composed of neuronal, glial, and precursor cells, with dopaminergic neurons accounting for the largest cell population. Pathway analysis revealed cell type-specific dysregulated biological processes in Parkin-deficient cells, including gene expression differences in dopaminergic neurons that control mitophagy and dopamine homeostasis, whereas microglia showed changes in calcium homeostasis and inflammatory signaling. Functional analysis verified elevated secretion of monocyte chemotactic protein 1 in PRKN-mutant co-cultures compared with controls, linking Parkin deficiency to increased microglial chemotactic signaling. Furthermore, lower intracellular calcium levels and diminished calcium release following treatment confirmed impaired calcium homeostasis in PRKN-mutant microglia. ConclusionsProfiling at the single-cell level resolved distinct cell subpopulations, enabling us to identify cell type-specific pathway disturbances underlying Parkin deficiency. This unique dataset provides a basis for understanding the impairment of individual cell types and the impact of cellular crosstalk in Parkinsons disease pathology.

molecular biology↗

bioRxiv2025

Micronuclear collapse under oxidative stress drives amphisome-mediated export of DNA in Parkinson disease

The diversity of extracellular vesicle (EV) subpopulations and their impact on intercellular communication are increasingly recognized, but how organelle dysfunction shapes EV content in neurodegenerative diseases remains unclear. Mitochondrial and lysosomal functional defects are hallmarks of Parkinsons disease (PD). Here we uncover a novel pathway linking this dysfunctional axis to EV remodeling and immune activation. We show that mitochondrial reactive oxygen species (ROS) induce genomic instability and micronuclei formation in PD fibroblasts, with ruptured micronuclei being sequestered into amphisomes and exported through small EVs. These EVs are enriched in oxidized mitochondrial and nuclear DNA, which potently stimulate microglial inflammatory responses. Mechanistically, this work identifies micronuclei not as passive byproducts of genome instability but as active intermediates in EV cargo loading. Importantly, treatment with the mitochondria-targeted antioxidant AntiOxCIN4 elicited a mitohormetic response, enhancing ATM-mediated DNA damage repair, restoring mitochondrial dynamics, and improving lysosomal function. This reduced the incorporation of oxidized DNA into EVs and blunted their pro-inflammatory activity. Together, our findings reveal a previously unrecognized mechanism by which mitochondrial-lysosomal dysfunction drives the release of DNA-enriched EVs that fuel neuroinflammation in a neurodegenerative context. Targeting mitochondrial quality control to limit oxidized cargo in EVs emerges as a potential strategy to mitigate early inflammatory events in PD.

neuroscience↗

bioRxiv2025

PINK1 regulates cholesterol homeostasis via SCAP phosphorylation in human dopaminergic neurons

Cholesterol is a key lipid enriched in neuronal membranes and essential for signaling and synaptic transmission. An imbalance in cholesterol levels may affect synaptic plasticity and contribute to neurodegeneration. Here, we identify in human dopaminergic neurons a mechanism linking loss of function of the Parkinsons disease (PD) gene PINK1 to altered cholesterol homeostasis. Loss of functional PINK1 impaired SCAP phosphorylation at Ser822 and Ser838, stabilizing SCAP and driving excess cholesterol biosynthesis. Cholesterol accumulated at the plasma membrane and in flotillin-rich lipid rafts, causing reduced neurotransmitter uptake and altering the distribution of dopamine transporter (DAT). Restoring PINK1 expression normalized cholesterol biosynthesis and levels. Moreover, the cholesterol-lowering drugs simvastatin and {beta}-cyclodextrin rescued DAT distribution and neurotransmitter uptake defects. These findings demonstrate that PINK1 influences cholesterol homeostasis through SCAP phosphorylation at Ser822 and Ser838 and that restoring cholesterol levels mitigates phenotypes observed in PINK1 PD neurons. These findings further highlight the cross-talk between mitochondria and lipid homeostasis in PD models, underscoring the relevance of cholesterol levels to dopaminergic functions. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/672574v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@165b4d4org.highwire.dtl.DTLVardef@42e3a2org.highwire.dtl.DTLVardef@16ea6f7org.highwire.dtl.DTLVardef@193e170_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

neuroscience↗

bioRxiv2024

Impaired neurogenesis and synaptogenesis in iPSC-derived Parkinson's patient cortical neurons with D620N VPS35 mutation

Presynaptic dysfunction is an important early process in the pathophysiology of Parkinsons disease (PD) that drives disease progression. To gain insight into the intrinsic synapse impairment in PD, we performed comprehensive electrophysiological and morphological analysis of iPSC-derived cortical neurons derived from PD patients with the VPS35-D620N mutation. Our findings reveal significant impairment in neurogenesis and synaptogenesis within individual patient neurons, culminating to synaptic dysfunction even in the absence of neuronal interactions. The neurons exhibited significantly reduced synaptic responsiveness, fewer synapse and decreased dendritic length and complexity. Thus, the VPS35-D620N mutation in human cortical neurons independently can cause pathophysiology via synaptic dysfunction. Our study highlights the urgent need to develop disease-modifying therapies aimed at preserving synaptic function in PD.

neuroscience↗

bioRxiv2019

Parkinson’s disease phenotypes in patient specific brain organoids are improved by HP-β-CD treatment

The etiology of Parkinsons disease (PD) is only partially understood despite the fact that environmental causes, risk factors, and specific gene mutations are contributors to the disease. Biallelic mutations in the PTEN-induced putative kinase 1 (PINK1) gene involved in mitochondrial homeostasis, vesicle trafficking, and autophagy, are sufficient to cause PD. By comparing PD patient-derived cells, we show differences in their energetic profile, imbalanced proliferation, apoptosis, mitophagy, and a reduced differentiation efficiency to dopaminergic neurons compared to control cells. Using CRISPR/Cas9 gene editing, correction of a patients point mutation ameliorated the metabolic properties and neuronal firing rates but without reversing the differentiation phenotype. However, treatment with 2-Hydroxypropyl-{beta}-Cyclodextrin (HP-{beta}-CD) increased the mitophagy capacity of neurons leading to an improved dopaminergic differentiation of patient specific neurons in midbrain organoids. In conclusion, we show that treatment with a repurposed compound is sufficient for restoring dopaminergic differentiation of PD patient-derived cells.

neuroscience↗

bioRxiv2019

Inhibition of Lipin lipid phosphatase hyperactivity rescues TorsinA neurological disease

TOR1A/TorsinA mutations cause poorly explained neurological diseases. A dominantly inherited mutation causes isolated dystonia, while biallelic mutations cause a recessive infant-onset syndrome with cases of lethality. Here we report an unexpected connection between lipid metabolism and these diseases. Lipin phosphatidic acid phosphatase activity was abnormally regulated in TorsinA dystonia patient cells, and in the brains of three different TorsinA disease model mice. Lipin activity was causative to symptoms given that lowering Lipin1 in vivo strongly intervened against lethality in disease mice. Furthermore, Lipin hyperactivity caused cell death in vitro, and Lipin1 deficiency suppressed neurodegeneration in vivo. In addition, it protected the striatal cholinergic interneurons that are implicated in TorsinA movement disorders, and concomitantly suppressed abnormal motor behaviors of TorsinA mice. These data establish the central role of Lipin lipid enzyme hyperactivity in TorsinA disease and show that Lipin inhibition is a therapeutic target for these incurable conditions.\n\nOne Sentence SummaryLipin inhibition rescues TorsinA neurological disease

genetics↗