Biology subjects

Moehle, M.

Publications and source records attributed to Moehle, M..

4 recordsLinked to original sources

bioRxiv2025

M5 positive allosteric modulation alleviates parkinsonian motor deficits

Parkinsons disease is a neurodegenerative movement disorder which is characterized by cardinal motor symptoms of tremor at rest, rigidity, bradykineasia, and postural instability. Underlying these cardinal motor symptoms is thought to be death and dysfunction of nigrostriatal dopamine neurons, and the gold-standard treatment of Parkinsons disease is dopamine replacement therapy with the dopamine precursor L-DOPA. While efficacious, L-DOPA does not treat all motor symptoms and can have serious treatment-related side effects called L-DOPA induced dyskinesias, indicating an immense need for new targets to modulate dopaminergic function for anti-parkinsonian efficacy. One such potential target is the M5 muscarinic acetylcholine receptor, which has a unique expression profile where it is selectively expressed in midbrain dopaminergic neurons and their terminals in the striatum, and previous studies have indicated that M5 can modulate dopamine release and patterning of firing of dopamine neurons. Given this unique expression profile and function of M5, this receptor has an untested potential to modulate parkinsonian motor phenotypes. To test the potential for M5 to modulate Parkinsonian-like motor deficits and dyskinesia, we employed the unilateral 6-OHDA lesioned mouse model to create a hemi-parkinsonian state. Using multiple behavioral assays, including the cylinder test, forepaw adjusting steps assay, and in the Erasmus ladder, in conjunction with prototypical M5 pharmacological tool compounds, we investigated the ability of M5 to modulate parkinsonian motor deficits. Additionally, we tested the ability of M5 to modulate established L-DOPA induced dyskinesia or cause dyskinesia on its own. Overall, we found that M5 PAM alleviates forepaw asymmetry, bradykinesia, and spatial aspects of gait in the Erasmus ladder. Excitingly, M5 PAM does not cause robust dyskinesia, does not affect already established L-DOPA-induced dyskinesia, and does not affect L-DOPA motor efficacy. Taken together with previous findings, the current study suggests that M5 receptors are an exciting novel therapeutic strategy for ameliorating parkinsonian motor deficits even in late-stage models of severe PD without lessening L-DOPAs motor benefit and without affecting existing symptoms of L-DOPA-induced dyskinesia.

neuroscience↗

bioRxiv2025

Pathological α-Synuclein Perturbs Nuclear Integrity

Pathological aggregates of -synuclein are a hallmark of a group of neurodegenerative disorders collectively termed synucleinopathies. The physiological function of -synuclein, and the detrimental effects of the pathological variants of -synuclein have been widely debated, but recent evidence has suggested an emerging consensus on a critical role for -synuclein in regulating synaptic function. However, a controversial role for -synuclein in nuclear function in both normal and pathogenic states has been proposed, and the degree to which -synuclein localizes within the nucleus and subsequent impact on the nucleus are poorly understood. To begin to address this controversy, we employed synucleinopathy murine and cell culture models, as well as postmortem human Lewy Body Dementia tissue to elucidate the extent to which pathological -synuclein localizes within the nuclear compartments, and the downstream consequences of this localization. We observed pathological aggregation of -synuclein within the nucleus in both murine models and human postmortem Lewy Body Dementia cortex via quantitative super resolution microscopy. In both mouse and human brain tissue the presence of -synuclein in the nucleus correlated with abnormal morphology of nuclei. This pathological accumulation of -synuclein in the nucleus was not observed in control mice, human tissue without pathology, or control cells. We subsequently examined the mechanistic consequences of pathological accumulation of -synuclein in the nucleus. Synucleinopathy models displayed increased levels of the DNA damage marker 53BP1. Furthermore, cells with pathological -synuclein exhibited elevated markers of nuclear envelope damage and abnormal expression of nuclear envelope repair markers. Our cell culture data also suggests altered RNA localization in response to pathological -synuclein accumulation within the nucleus. Lastly, we show that nuclear Lewy-like pathology leads to increased sensitivity to nuclear targeted toxins. Taken together, these results rigorously illustrate nuclear localization of pathological -synuclein with super resolution methodology and provide novel insight into the ensuing impact on nuclear integrity and function.

neuroscience↗

bioRxiv2025

Aggregated α-synuclein leads to corticostriatal synaptic dysfunction

Neuronal inclusions of -synuclein (-syn) are pathological hallmarks of Parkinsons disease (PD) and Dementia with Lewy Bodies (DLB). -Syn pathology accumulates in cortical neurons which project to the striatum. To begin to understand how -syn pathology effects cortico-striatal synapses, pre-formed -syn fibrils (PFF) were injected into the striatum to induce robust -syn aggregation in corticostriatal-projecting neurons. Electrophysiological recordings of striatal spiny projection neurons (SPNs) acute slices found a significant decrease in evoked corticostriatal glutamate release in mice with PFF-induced aggregates compared to monomer injected mice. Expansion microscopy, confocal microscopy and Imaris reconstructions were used to identify vGLUT1 positive presynaptic terminals juxtaposed to Homer-positive postsynaptic densities, termed synaptic foci. Quantitation of synaptic loci density revealed a loss of corticostriatal synapses. Immunoblots of the striatum show reductions in expression of pre-synaptic proteins with selective reduction in AMPA and NMDA receptor subunits in mice with -syn aggregates compared to controls. Paradoxically, a small percentage of remaining VLGUT1+ synaptic loci with small, intrasynaptic -syn aggregates showed enlarged volumes compared to nearby synapses without -syn aggregates. Our combined physiology and high-resolution imaging data point to dysfunction of corticostriatal synapses in mice harboring {square}-synuclein inclusions, which may contribute to impaired basal ganglia circuitry in PD. Highlights- Corticostriatal glutamate drive is impaired in the presence of pathological -syn - -Syn aggregation causes early loss of corticostriatal synapses - Synaptic loci positive for small -syn aggregates show volume increases - Striatal expression of select synaptic proteins are reduced in animals with -syn pathology

neuroscience↗

bioRxiv2023

Inhibition of LRRK2 kinase activity rescues deficits in striatal dopamine dynamics in VPS35 p.D620N knock-in mice

Dysregulation of dopamine neurotransmission profoundly affects motor, motivation and learning behaviors, and is often observed during the prodromal phase of Parkinsons disease (PD). However, the mechanism underlying these pathophysiological changes remains to be elucidated. Mutations in vacuolar protein sorting 35 (VPS35) and leucine-rich repeat kinase 2 (LRRK2) both lead to autosomal dominant PD, and VPS35 and LRRK2 may physically interact to govern the trafficking of synaptic cargos within the endo-lysosomal network in a kinase-dependent manner. To better understand the functional role of VPS35 and LRRK2 on dopamine physiology, we examined Vps35 haploinsufficient (Haplo) and Vps35 p.D620N knock-in (VKI) mice and how their behavior, dopamine kinetics and biochemistry are influenced by LRRK2 kinase inhibitors. We found Vps35 p.D620N significantly elevates LRRK2-mediated phosphorylation of Rab10, Rab12 and Rab29. In contrast, Vps35 haploinsufficiency reduces phosphorylation of Rab12. While striatal dopamine transporter (DAT) expression and function is similarly impaired in both VKI and Haplo mice, that physiology is normalized in VKI by treatment with the LRRK2 kinase inhibitor, MLi-2. As a corollary, VKI animals show a significant increase in amphetamine induced hyperlocomotion, compared to Haplo mice, that is also abolished by MLi-2. Taken together, these data show Vps35 p.D620N confers a gain-of-function with respect to LRRK2 kinase activation, and VPS35 and LRRK2 functionally interact to regulate DAT trafficking and striatal dopamine neurotransmission.

neuroscience↗