Biology subjects

Volpicelli-Daley, L. A.

Publications and source records attributed to Volpicelli-Daley, L. A..

6 recordsLinked to original sources

bioRxiv2026

α-Synuclein aggregates in corticostriatal terminals impair glutamatergic transmission in the absence of neurodegeneration

Substantia nigra pars compacta dopamine neuron loss and Lewy pathology, aggregates of -synuclein, characterize Parkinsons disease and Dementia with Lewy Bodies. Lewy pathology localizes to cortical neurons, and is found as Lewy neurites in the striatum, but its effects on excitatory synaptic function are just beginning to be understood. Corticostriatal projections regulate motor and cognitive behaviors impaired in these disorders. Here, -synuclein aggregation was induced in mouse M2 cortex, a vulnerable region in human disease. Early after initiation, aggregates localized to corticostriatal vesicular glutamate transporter 1 (vGLUT1)-positive terminals, with sparing of spiny projection neuron (SPN) soma, and dopamine terminals and neurons. Corticostriatal presynaptic aggregates significantly impaired glutamatergic transmission, without overt cortical neuron loss, and were associated with decreased synaptic density and volume. Thus, formation of presynaptic -synuclein aggregates impairs corticostriatal function without degeneration of cortical neurons or striatal dopamine terminals, suggesting pathologic -synuclein is sufficient for synaptic loss. Our findings also point to early synaptic dysfunction as a therapeutic target in Lewy body diseases.

neuroscience↗

bioRxiv2026

Neural cell state modulation by PARK2 and dopaminergic neuroprotection by small molecule Parkin agonism

Parkin, an E3 ubiquitin ligase encoded by PARK2, plays a key role in both hereditary and sporadic Parkinsons disease (PD), yet there are no therapies currently available that can target this important pathway. Here, we show that Parkin is critical for successful neuronal differentiation and survival, and we develop small-molecule Parkin agonists that can protect dopaminergic neurons. Upon differentiation of neural progenitor cells, loss of Parkin results in a reduced capacity to maintain neuronal cell state, dopaminergic neuronal phenotypes, and stress resistance. Moreover, Parkin loss disrupted cell morphology and the stability of neurites. Transcriptional and single-cell analyses reveal that Parkin controls critical pathways regulating stem-like cell transitions and is needed for stable neuronal maturation. We also examined the effects of FB231, a small molecule enhancer of Parkin E3 ligase activity, in models of PD. FB231 reduced pathological -synuclein and enhanced cell survival in human iPSC-derived dopaminergic neurons treated with -synuclein preformed fibrils. Furthermore, FB231 attenuated -synuclein pathology and dopaminergic neurodegeneration in a gut -synuclein murine model of PD. Our findings support that Parkin plays a crucial role in maintaining neuronal homeostasis and that pharmacologic activation of Parkin may be a promising strategy to attenuate neurodegeneration in PD.

neuroscience↗

bioRxiv2024

Cortical synaptic vulnerabilities revealed in a α-synuclein aggregation model of Parkinson's disease

-Synuclein aggregates characterize -synucleinopathies, including Parkinsons disease and Dementia with Lewy bodies. A majority of people with these disorders experience cognitive decline, and its extent correlates with cortical -synuclein pathology. Mechanisms by which pathology targets cortical circuits remain to be understood so that the debilitating non-motor impairments can be addressed. Overt neuronal loss is not a major feature of cortical pathology, but a reduction of presynaptic sites has been reported at late stages of PD. We here define excitatory synapses as neuronal loci affected by -synuclein aggregation, showing that they are progressively lost, and identify temporal and spatial patterns of synaptic vulnerability. Results were obtained in a mouse model using intrastriatal injection of pre-formed -synuclein fibrils to template the aggregation of endogenous -synuclein in cortical neurons. Lewy neurite-like aggregates were predominantly observed in axons. Super-resolved imaging showed -synuclein aggregation within cortical synapses and revealed that synaptic aggregation is most severe proximal to Lewy neurite-like structures and linked to the earliest detectable loss of excitatory synapses. Excitatory synapses also exhibited ultrastructural aberrations, including a redistribution of pre- and post-synaptic protein clusters away from contact sites and reduced synaptic vesicle size. As pathology advanced, VGLUT1-positive intracortical synapses, enriched in -synuclein, were progressively vulnerable in this striatal seeding model, while VGLUT2-positive long-range synapses with minimal -synuclein were spared. Inhibitory synapses were not affected. In agreement with a disruptive role of synaptic -synuclein aggregation, super-resolved mesoscale imaging determined that synaptic but not non-synaptic -synuclein pathology is correlated with excitatory synapse loss. Physiological recordings confirmed impaired excitatory neurotransmission. Pathology propagation tracked cortical connectivity, with intra-column synapse loss correlated between interconnected layers V and II/III. Contralateral areas receiving projections from pathologic layer V also exhibited synapse loss. These findings reveal synapses as principal cellular loci of -synuclein pathology and define how molecular and circuit-based mechanisms underlie the cortical progression of synaptic pathology in -synucleinopathies.

neuroscience↗

bioRxiv2022

Neuronopathic GBA1 L444P mutation accelerates glucosylsphingosine levels and formation of hippocampal alpha-synuclein inclusions

The most common genetic risk factor for Parkinsons disease (PD) is heterozygous mutations in the GBA1 gene which encodes for the lysosomal enzyme, glucocerebrosidase (GCase). GCase impairments are associated with an accumulation of abnormal -synuclein (-syn) called Lewy pathology, which characterizes PD. PD patients heterozygous for the GBA1 L444P mutation (GBA1+/L444P) have a 5.6-fold increased risk of cognitive impairments. In this study, we used GBA1+/L444P mice to determine the effects of this severe GBA1 mutation on lipid metabolism, expression of synaptic proteins, behavior, and -syn inclusion formation. GBA1+/L444P mice showed reduced GCase activity in limbic brain regions and expressed lower levels of hippocampal vGLUT1 compared to wildtype (GBA1+/+) mice. GBA+/L444P mice also demonstrated impaired fear conditioning, but no motor deficits. We show, using mass spectrometry, that mutant GCase and age increased levels of glucosylsphingosine (GlcSph), but not glucosylceramide (GlcCer), in the brains and serum of GBA1+/L444P mice. Aged GBA1+/+ mice also showed increased levels of GlcSph, and decreased GlcCer. To model disease pathology, templated -syn pathology was used. -Syn inclusions were increased in the hippocampus of GBA1+/L444P mice compared to GBA1+/+ mice, but not in the cortex, or substantia nigra pars compacta (SNc). Pathologic -syn did not cause a loss of dopamine neurons in the SNc. Treatment with a GlcCer synthase inhibitor prevented loss of cortical -syn inclusions, but not loss of dopamine neurons. Overall, these data suggest the critical importance to evaluate the contribution of hippocampal pathologic -syn and brain and serum glucosylsphingosine in synucleinopathies. SIGNIFICANCE STATEMENTSynucleinopathies, such as Parkinsons disease (PD) and Dementia with Lewy bodies (DLB), are both pathologically characterized by abnormal -synuclein (-syn). Mutant GBA1 is a risk factor for both PD and DLB where a reduction of glucocerebrosidase (GCase) activity is seen. Collectively, this indicates the significance of evaluating mutant GCase in synucleinopathies. Our data suggest the critical importance to evaluate the contribution of hippocampal pathologic -syn and brain and serum glucosylsphingosine (GlcSph) accumulation in synucleinopathies. Moreover, these pathologic outcomes may contribute to the nonmotor symptoms clinically observed in PD and DLB. Our findings highlight the importance of GlcSph as a relevant biomarker for future therapeutics.

neuroscience↗

bioRxiv2021

Inhibition of LRRK2 kinase activity promotes anterograde axonal transport and presynaptic targeting of α-synuclein

Pathologic inclusions composed of -synuclein called Lewy pathology are hallmarks of Parkinsons Disease (PD). Dominant inherited mutations in leucine rich repeat kinase 2 (LRRK2) are the most common genetic cause of PD. Lewy pathology is found in the majority of individuals with LRRK2-PD, particularly those with the G2019S-LRRK2 mutation. Lewy pathology in LRRK2-PD associates with increased non-motor symptoms such as cognitive deficits, anxiety, and orthostatic hypotension. Thus, understanding the relationship between LRRK2 and -synuclein could be important for determining the mechanisms of non-motor symptoms. In PD models, expression of mutant LRRK2 reduces membrane localization of - synuclein, and enhances formation of pathologic -synuclein, particularly when synaptic activity is increased. -Synuclein and LRRK2 both localize to the presynaptic terminal. LRRK2 plays a role in membrane traffic, including axonal transport, and therefore may influence -synuclein synaptic localization. This study shows that LRRK2 kinase activity influences -synuclein targeting to the presynaptic terminal. We used the selective LRRK2 kinase inhibitors, MLi-2 and PF-06685360 (PF-360) to determine the impact of reduced LRRK2 kinase activity on presynaptic localization of -synuclein. Expansion microscopy (ExM) in primary hippocampal cultures and the mouse striatum, in vivo, was used to more precisely resolve the presynaptic localization of -synuclein. Live imaging of axonal transport of -synuclein-GFP was used to investigate the impact of LRRK2 kinase inhibition on -synuclein axonal transport towards the presynaptic terminal. Reduced LRRK2 kinase activity increases -synuclein overlap with presynaptic markers in primary neurons, and increases anterograde axonal transport of - synuclein-GFP. In vivo, LRRK2 inhibition increases -synuclein overlap with glutamatergic, cortico-striatal terminals, and dopaminergic nigral-striatal presynaptic terminals. The findings suggest that LRRK2 kinase activity plays a role in axonal transport, and presynaptic targeting of -synuclein. These data provide potential mechanisms by which LRRK2-mediated perturbations of -synuclein localization could cause pathology in both LRRK2-PD, and idiopathic PD.

neuroscience↗

bioRxiv2021

Alpha-synuclein alters the faecal viromes of rats in a gut-initiated model of Parkinson's disease

Parkinsons disease (PD) is a chronic neurological disorder associated with the misfolding of alpha-synuclein (-syn) into Lewy body aggregates within nerve cells that contribute to their neurodegeneration. Recent evidence suggests -syn aggregation may begin in the gut and travel to the brain along the vagus nerve, with microbes a potential trigger initiating the misfolding of -syn. However, changes in the gut virome in response to -syn alterations have not been investigated. In this study, we show longitudinal changes in the faecal virome of rats administered either monomeric or preformed fibrils (PFF) of -syn directly into their enteric nervous system. Differential changes in rat viromes were observed when comparing monomeric and PFF -syn. The virome {beta}-diversity changes after -syn treatment were compounded by the addition of LPS as an adjunct. Changes in the diversity of rat faecal viromes were observed after one month and did not resolve within the studys five month observational period. Overall, these results suggest that microbiome alterations associated with PD may, partially, be reactive to host -syn associated changes.

microbiology↗