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Parkinsonism & Related Disorders Jun 2024Among gene mutations and variants linked to an increased risk of PD, mutations of leucine-rich repeat kinase 2 gene (LRRK2) are among the most frequently associated with...
INTRODUCTION
Among gene mutations and variants linked to an increased risk of PD, mutations of leucine-rich repeat kinase 2 gene (LRRK2) are among the most frequently associated with early- and late-onset PD. Clinical and neuropathological characteristics of idiopathic-PD (iPD) and LRRK2-PD are similar, and these similarities suggest that the pathomechanisms between these two conditions are shared. LRRK2 mutations determine a gain-of-function and yield higher levels of lrrk2 across body tissues, including brain. On another side, recent animal studies supported the potential use of low dose radiation (LDR) to modify the pathomechanisms of diseases such as Alzheimer's disease (AD).
METHODS
We assessed if a single total-body LDR (sLDR) exposure in normal swine could alter expression levels of the following PD-associated molecules: alpha-synuclein (α-syn), phosphorylated-α-synuclein (pα-syn), parkin, tyrosine hydroxylase (th), lrrk2, phosphorylated-lrrk2 (pS935-lrrk2), and some LRRK2 substrates (Rab8a, Rab12) across different brain regions. These proteins were measured in frontal cortex, hippocampus, striatum, thalamus/hypothalamus, and cerebellum of 9 radiated (RAD) vs. 6 sham (SH) swine after 28 days from a sLDR of 1.79Gy exposure.
RESULTS
Western Blot analyses showed lowered lrrk2 levels in the striatum of RAD vs. SH swine (p < 0.05), with no differences across the remaining brain regions. None of the other protein levels differed between RAD and SH swine in any examined brain regions. No lrrk2 and p-lrrk2 (S935) levels differed in the lungs of RAD vs. SH swine.
CONCLUSIONS
These findings show a specific striatal lrrk2 lowering effect due to LDR and support the potential use of LDR to interfere with the pathomechanisms of PD.
PubMed: 38843617
DOI: 10.1016/j.parkreldis.2024.107024 -
Journal of Medicinal Chemistry Jun 2024Increasing research efforts focus on exploiting antibodies to inhibit the amyloid formation of neurodegenerative proteins. Nevertheless, it is challenging to discover...
Increasing research efforts focus on exploiting antibodies to inhibit the amyloid formation of neurodegenerative proteins. Nevertheless, it is challenging to discover antibodies that inhibit this process in a specific manner. Using ribosome display, we screened for synthetic single-domain antibodies, i.e., sybodies, of the P1 region of α-synuclein (residues 36-42), a protein that forms amyloid in Parkinson's disease and multiple-system atrophy. Hits were assessed for direct binding to a P1 peptide and the inhibition of amyloid formation. We discovered a sybody, named αSP1, that inhibits amyloid formation of α-synuclein at substoichiometric concentrations in a specific manner, even within highly crowded heterogeneous mixtures. Fluorescence resonance energy transfer-based binding assays and seeding experiments with and without αSP1 further demonstrate the importance of the P1 region for both primary and secondary nucleation mechanisms of amyloid assembly.
Topics: alpha-Synuclein; Humans; Amyloid; Single-Domain Antibodies; Protein Binding
PubMed: 38842931
DOI: 10.1021/acs.jmedchem.3c02408 -
Neurotoxicity Research Jun 2024Parkinson's disease with dementia (PDD) is a neurological disorder that clinically and neuropathologically overlaps with Parkinson's disease (PD) and Alzheimer's disease...
Parkinson's disease with dementia (PDD) is a neurological disorder that clinically and neuropathologically overlaps with Parkinson's disease (PD) and Alzheimer's disease (AD). Although it is assumed that alpha-synuclein ( -Syn), amyloid beta (A ), and the protein Tau might synergistically induce cholinergic neuronal degeneration, presently the pathological mechanism of PDD remains unclear. Therefore, it is essential to delve into the cellular and molecular aspects of this neurological entity to identify potential targets for prevention and treatment strategies. Cholinergic-like neurons (ChLNs) were exposed to rotenone (ROT, 10 M) for 24 h. ROT provokes loss of , generation of reactive oxygen species (ROS), phosphorylation of leucine-rich repeated kinase 2 (LRRK2 at Ser) concomitantly with phosphorylation of -synuclein ( -Syn, Ser), induces accumulation of intracellular A (iA ), oxidized DJ-1 (Cys), as well as phosphorylation of TAU (Ser/Thr), increases the phosphorylation of c-JUN (Ser/Ser), and increases expression of proapoptotic proteins TP53, PUMA, and cleaved caspase 3 (CC3) in ChLNs. These neuropathological features resemble those reproduced in presenilin 1 (PSEN1) E280A ChLNs. Interestingly, anti-oxidant and anti-amyloid cannabidiol (CBD), JNK inhibitor SP600125 (SP), TP53 inhibitor pifithrin- (PFT), and LRRK2 kinase inhibitor PF-06447475 (PF475) significantly diminish ROT-induced oxidative stress (OS), proteinaceous, and cell death markers in ChLNs compared to naïve ChLNs. In conclusion, ROT induces p- -Syn, iA , p-Tau, and cell death in ChLNs, recapitulating the neuropathology findings in PDD. Our report provides an excellent in vitro model to test for potential therapeutic strategies against PDD. Our data suggest that ROT induces a neuropathologic phenotype in ChLNs similar to that caused by the mutation PSEN1 E280A.
Topics: Rotenone; Cholinergic Neurons; Animals; Parkinson Disease; alpha-Synuclein; Dementia; Phenotype; Reactive Oxygen Species; Humans; Cells, Cultured
PubMed: 38842585
DOI: 10.1007/s12640-024-00705-3 -
EMBO Molecular Medicine Jun 2024Synucleinopathies such as Parkinson's disease (PD) are defined by the accumulation and aggregation of the α-synuclein protein in neurons, glia and other tissues. We...
Synucleinopathies such as Parkinson's disease (PD) are defined by the accumulation and aggregation of the α-synuclein protein in neurons, glia and other tissues. We have previously shown that destabilization of α-synuclein tetramers is associated with familial PD due to SNCA mutations and demonstrated brain-region specific alterations of α-synuclein multimers in sporadic PD patients following the classical Braak spreading theory. In this study, we assessed relative levels of disordered and higher-ordered multimeric forms of cytosolic α-synuclein in blood from familial PD with G51D mutations and sporadic PD patients. We used an adapted in vitro-cross-linking protocol for human EDTA-whole blood. The relative levels of higher-ordered α-synuclein tetramers were diminished in blood from familial PD and sporadic PD patients compared to controls. Interestingly, the relative amount of α-synuclein tetramers was already decreased in asymptomatic G51D carriers, supporting the hypothesis that α-synuclein multimer destabilization precedes the development of clinical PD. Our data, therefore suggest that measuring α-synuclein tetramers in blood may have potential as a facile biomarker assay for early detection and quantitative tracking of PD progression.
PubMed: 38839930
DOI: 10.1038/s44321-024-00083-5 -
Neurobiology of Disease Aug 2024Multiple system atrophy (MSA) is characterized by glial cytoplasmic inclusions (GCIs) containing aggregated α-synuclein (α-syn) in oligodendrocytes. The origin of...
Multiple system atrophy (MSA) is characterized by glial cytoplasmic inclusions (GCIs) containing aggregated α-synuclein (α-syn) in oligodendrocytes. The origin of α-syn accumulation in GCIs is unclear, in particular whether abnormal α-syn aggregates result from the abnormal elevation of endogenous α-syn expression in MSA or ingested from the neuronal source. Tubulin polymerization promoting protein (TPPP) has been reported to play a crucial role in developing GCI pathology. Here, the total cell body, nucleus, and cytoplasmic area density of SNCA and TPPP transcripts in neurons and oligodendrocytes with and without various α-syn pathologies in the pontine base in autopsy cases of MSA (n = 4) and controls (n = 2) were evaluated using RNAscope with immunofluorescence. Single-nucleus RNA-sequencing data for TPPP was evaluated using control frontal cortex (n = 3). SNCA and TPPP transcripts were present in the nucleus and cytoplasm of oligodendrocytes in both controls and diseased, with higher area density in GCIs and glial nuclear inclusions in MSA. Area densities of SNCA and TPPP transcripts were lower in neurons showing cytoplasmic inclusions in MSA. Indeed, TPPP transcripts were unexpectedly found in neurons, while the anti-TPPP antibody failed to detect immunoreactivity. Single-nucleus RNA-sequencing revealed significant TPPP transcript expression predominantly in oligodendrocytes, but also in excitatory and inhibitory neurons. This study addressed the unclear origin of accumulated α-syn in GCIs, proposing that the elevation of SNCA transcripts may supply templates for misfolded α-syn. In addition, the parallel behavior of TPPP and SNCA transcripts in GCI development highlights their potential synergistic contribution to inclusion formation. In conclusion, this study advances our understanding of MSA pathogenesis, offers insights into the dynamics of SNCA and TPPP transcripts in inclusion formation, and proposes regulating their transcripts for future molecular therapy to MSA.
Topics: alpha-Synuclein; Multiple System Atrophy; Humans; Oligodendroglia; Inclusion Bodies; Aged; Female; Male; Middle Aged; Nerve Tissue Proteins; Neurons; Aged, 80 and over
PubMed: 38839023
DOI: 10.1016/j.nbd.2024.106551 -
Neurobiology of Disease Aug 2024α-Synuclein (α-syn) is a small protein that is involved in cell vesicle trafficking in neuronal synapses. A progressive aggregation of this protein is the expected...
α-Synuclein (α-syn) is a small protein that is involved in cell vesicle trafficking in neuronal synapses. A progressive aggregation of this protein is the expected molecular cause of Parkinson's disease, a disease that affects millions of people around the world. A growing body of evidence indicates that phospholipids can strongly accelerate α-syn aggregation and alter the toxicity of α-syn oligomers and fibrils formed in the presence of lipid vesicles. This effect is attributed to the presence of high copies of lysines in the N-terminus of the protein. In this study, we performed site-directed mutagenesis and replaced one out of two lysines at each of the five sites located in the α-syn N-terminus. Using several biophysical and cellular approaches, we investigated the extent to which six negatively charged fatty acids (FAs) could alter the aggregation properties of K10A, K23A, K32A, K43A, and K58A α-syn. We found that FAs uniquely modified the aggregation properties of K43A, K58A, and WT α-syn, as well as changed morphology of amyloid fibrils formed by these mutants. At the same time, FAs failed to cause substantial changes in the aggregation rates of K10A, K23A, and K32A α-syn, as well as alter the morphology and toxicity of the corresponding amyloid fibrils. Based on these results, we can conclude that K10, K23, and K32 amino acid residues play a critical role in protein-lipid interactions since their replacement on non-polar alanines strongly suppressed α-syn-lipid interactions.
Topics: alpha-Synuclein; Mutagenesis, Site-Directed; Humans; Amyloid; Fatty Acids
PubMed: 38839022
DOI: 10.1016/j.nbd.2024.106553 -
Applied Biosciences Jun 2024Synucleinopathies, typified by Parkinson's disease (PD), entail the accumulation of -synuclein (Syn) aggregates in nerve cells. Various Syn mutants, including the Syn...
Synucleinopathies, typified by Parkinson's disease (PD), entail the accumulation of -synuclein (Syn) aggregates in nerve cells. Various Syn mutants, including the Syn A53T variant linked to early-onset PD, increase the propensity for Syn aggregate formation. In addition to disrupting protein homeostasis and inducing proteostatic stress, the aggregation of Syn in PD is associated with an imbalance in iron metabolism, which increases the generation of reactive oxygen species and causes oxidative stress. This study explored the impact of Syn A53T expression in transgenic hairy roots of four medicinal plants (, , , and ). In all tested plants, Syn A53T expression triggered proteotoxic stress and perturbed iron homeostasis, mirroring the molecular profile observed in human and animal nerve cells. In addition to the common eukaryotic defense mechanisms against proteostatic and oxidative stresses, a plant stress response generally includes the biosynthesis of a diverse set of protective secondary metabolites. Therefore, the hairy root cultures expressing Syn A53T offer a platform for identifying secondary metabolites that can ameliorate the effects of Syn, thereby aiding in the development of possible PD treatments and/or treatments of synucleinopathies.
PubMed: 38835931
DOI: 10.3390/applbiosci3020016 -
NPJ Parkinson's Disease Jun 2024A new Parkinson's disease (PD) subtyping model has been recently proposed based on the initial location of α-synuclein inclusions, which divides PD patients into the...
A new Parkinson's disease (PD) subtyping model has been recently proposed based on the initial location of α-synuclein inclusions, which divides PD patients into the brain-first subtype and the body-first subtype. Premotor RBD has proven to be a predictive marker of the body-first subtype. We found compared to PD patients without possible RBD (PD, representing the brain-first subtype), PD patients with possible premotor RBD (PD, representing the body-first subtype) had lower Movement Disorders Society Unified Parkinson's Disease Rating Scale part III (MDS UPDRS-III) score (p = 0.022) at baseline but presented a faster progression rate (p = 0.009) in MDS UPDRS-III score longitudinally. The above finding indicates the body-first subtype exhibited a faster disease progression in motor impairments compared to the brain-first subtype and further validates the proposed subtyping model.
PubMed: 38834646
DOI: 10.1038/s41531-024-00730-1 -
Neurobiology of Disease Aug 2024Multiple system atrophy (MSA) and Parkinson's disease (PD) are neurodegenerative disorders characterized by α-synuclein pathology, disrupted iron homeostasis and...
BACKGROUND
Multiple system atrophy (MSA) and Parkinson's disease (PD) are neurodegenerative disorders characterized by α-synuclein pathology, disrupted iron homeostasis and impaired neurochemical transmission. Considering the critical role of iron in neurotransmitter synthesis and transport, our study aims to identify distinct patterns of whole-brain iron accumulation in MSA and PD, and to elucidate the corresponding neurochemical substrates.
METHODS
A total of 122 PD patients, 58 MSA patients and 78 age-, sex-matched health controls underwent multi-echo gradient echo sequences and neurological evaluations. We conducted voxel-wise and regional analyses using quantitative susceptibility mapping to explore MSA or PD-specific alterations in cortical and subcortical iron concentrations. Spatial correlation approaches were employed to examine the topographical alignment of cortical iron accumulation patterns with normative atlases of neurotransmitter receptor and transporter densities. Furthermore, we assessed the associations between the colocalization strength of neurochemical systems and disease severity.
RESULTS
MSA patients exhibited increased susceptibility in the striatal, midbrain, cerebellar nuclei, as well as the frontal, temporal, occipital lobes, and anterior cingulate gyrus. In contrast, PD patients displayed elevated iron levels in the left inferior occipital gyrus, precentral gyrus, and substantia nigra. The excessive iron accumulation in MSA or PD correlated with the spatial distribution of cholinergic, noradrenaline, glutamate, serotonin, cannabinoids, and opioid neurotransmitters, and the degree of this alignment was related to motor deficits.
CONCLUSIONS
Our findings provide evidence of the interaction between iron accumulation and non-dopamine neurotransmitters in the pathogenesis of MSA and PD, which inspires research on potential targets for pharmacotherapy.
Topics: Humans; Multiple System Atrophy; Parkinson Disease; Male; Female; Middle Aged; Aged; Brain; Magnetic Resonance Imaging; Iron; Neurotransmitter Agents; Brain Mapping
PubMed: 38830476
DOI: 10.1016/j.nbd.2024.106549 -
Proceedings of the National Academy of... Jun 2024
PubMed: 38830111
DOI: 10.1073/pnas.2408899121