The α-synuclein seed amplification assay: Interpreting a test of Parkinson's pathology.

The α-synuclein seed amplification assay (αSyn-SAA) sensitively detects Lewy pathology, the amyloid state of α-synuclein, in the cerebrospinal fluid (CSF) of patients with Parkinson's disease (PD). The αSyn-SAA harnesses the physics of seeding, whereby a superconcentrated solution of recombinant α-synuclein lowers the thermodynamic threshold (nucleation barrier) for aggregated α-synuclein to act as a nucleation catalyst ("seed") to trigger the precipitation (nucleation) of monomeric α-synuclein into pathology. This laboratory setup increases the signal for identifying a catalyst if one is present in the tissue examined.

The effects of chemogenetic targeting of serotonin-projecting pathways on L-DOPA-induced dyskinesia and psychosis in a bilateral rat model of Parkinson's disease.

Introduction: Parkinson's disease (PD) is commonly characterized by severe dopamine (DA) depletion within the substantia nigra (SN) leading to a myriad of motor and non-motor symptoms. One underappreciated and prevalent non-motor symptom, Parkinson's disease-associated psychosis (PDAP), significantly erodes patient and caregiver quality of life yet remains vastly understudied. While the gold standard pharmacotherapy for motor symptoms Levodopa (LD) is initially highly effective, it can lead to motor fluctuations like LD-induced dyskinesia (LID) and non-motor fluctuations such as intermittent PDAP.

Engineered AAV capsid transport mutants overcome transduction deficiencies in the aged CNS.

Adeno-associated virus (AAV)-based gene therapy has enjoyed great successes over the past decade, with Food and Drug Administration-approved therapeutics and a robust clinical pipeline. Nonetheless, barriers to successful translation remain. For example, advanced age is associated with impaired brain transduction, with the diminution of infectivity depending on anatomical region and capsid.

ENGINEERED NANOBODIES WITH PROGRAMMABLE TARGET ANTIGEN PROTEOLYSIS (PTAP) FUSIONS REGULATE INTRACELLULAR ALPHA-SYNUCLEIN IN VITRO AND IN VIVO.

Alpha-synuclein (αSyn) aggregation and the formation of Lewy pathology (LP) is a foundational pathophysiological phenomenon in synucleinopathies. Delivering therapeutic single-chain and single-domain antibodies that bind pathogenic targets can disrupt intracellular aggregation. The fusion of antibody fragments to a negatively-charged proteasomal targeting motif (PEST) creates bifunctional constructs that enhance both solubility and turnover.

Quinpirole inhibits levodopa-induced dyskinesias at structural and behavioral levels: Efficacy negated by co-administration of isradipine.

Dopamine depletion associated with parkinsonism induces plastic changes in striatal medium spiny neurons (MSN) that are maladaptive and associated with the emergence of the negative side-effect of standard treatment: the abnormal involuntary movements termed levodopa-induced dyskinesia (LID). Prevention of MSN dendritic spine loss is hypothesized to diminish liability for LID in Parkinson's disease. Blockade of striatal CaV1.

A comparison of machine learning approaches for the quantification of microglial cells in the brain of mice, rats and non-human primates.

Microglial cells are brain-specific macrophages that swiftly react to disruptive events in the brain. Microglial activation leads to specific modifications, including proliferation, morphological changes, migration to the site of insult, and changes in gene expression profiles. A change in inflammatory status has been linked to many neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease.

Downregulation of striatal Ca1.3 inhibits the escalation of levodopa-induced dyskinesia in male and female parkinsonian rats of advanced age.

In the past 25 years, the prevalence of Parkinson's disease (PD) has nearly doubled. Age remains the primary risk factor for PD and as the global aging population increases this trend is predicted to continue. Even when treated with levodopa, the gold standard dopamine (DA) replacement therapy, individuals with PD frequently develop therapeutic side effects.

Gene Therapy to Modulate Alpha-Synuclein in Synucleinopathies.

The protein alpha-Synuclein (α-Syn) is a key contributor to the etiology of Parkinson's disease (PD) with aggregation, trans-neuronal spread, and/or depletion of α-Syn being viewed as crucial events in the molecular processes that result in neurodegeneration. The exact succession of pathological occurrences that lead to neuronal death are still largely unknown and are likely to be multifactorial in nature. Despite this unknown, α-Syn dose and stability, autophagy-lysosomal dysfunction, and inflammation, amongst other cellular impairments, have all been described as participatory events in the neurodegenerative process.

Netrin-1 receptor UNC5C cleavage by active δ-secretase enhances neurodegeneration, promoting Alzheimer's disease pathologies.

Netrin-1, a family member of laminin-related secreted proteins, mediates axon guidance and cell migration during neural development. T835M mutation in netrin receptor UNC5C predisposes to the late-onset Alzheimer's disease (AD) and increases neuronal cell death. However, it remains unclear how this receptor is molecularly regulated in AD.

α-Synuclein antisense oligonucleotides as a disease-modifying therapy for Parkinson's disease.

Parkinson's disease (PD) is a prevalent neurodegenerative disease with no approved disease-modifying therapies. Multiplications, mutations, and single nucleotide polymorphisms in the SNCA gene, encoding α-synuclein (aSyn) protein, either cause or increase risk for PD. Intracellular accumulations of aSyn are pathological hallmarks of PD.

The BDNF Val66Met polymorphism (rs6265) enhances dopamine neuron graft efficacy and side-effect liability in rs6265 knock-in rats.

Prevalent in approximately 20% of the worldwide human population, the rs6265 (also called 'Val66Met') single nucleotide polymorphism (SNP) in the gene for brain-derived neurotrophic factor (BDNF) is a common genetic variant that can alter therapeutic responses in individuals with Parkinson's disease (PD). Possession of the variant Met allele results in decreased activity-dependent release of BDNF. Given the resurgent worldwide interest in neural transplantation for PD and the biological relevance of BDNF, the current studies examined the effects of the rs6265 SNP on therapeutic efficacy and side-effect development following primary dopamine (DA) neuron transplantation.

Striatal Nurr1 Facilitates the Dyskinetic State and Exacerbates Levodopa-Induced Dyskinesia in a Rat Model of Parkinson's Disease.

The transcription factor Nurr1 has been identified to be ectopically induced in the striatum of rodents expressing l-DOPA-induced dyskinesia (LID). In the present study, we sought to characterize Nurr1 as a causative factor in LID expression. We used rAAV2/5 to overexpress Nurr1 or GFP in the parkinsonian striatum of LID-resistant Lewis or LID-prone Fischer-344 (F344) male rats.

Author Correction: C/EBPβ regulates delta-secretase expression and mediates pathogenesis in mouse models of Alzheimer's disease.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Deficiency in BDNF/TrkB Neurotrophic Activity Stimulates δ-Secretase by Upregulating C/EBPβ in Alzheimer's Disease.

BDNF/TrkB neurotrophic signaling regulates neuronal development, differentiation, and survival, and deficient BDNF/TrkB activity underlies neurodegeneration in Alzheimer's disease (AD). However, exactly how BDNF/TrkB participates in AD pathology remains unclear. Here, we show that deprivation of BDNF/TrkB increases inflammatory cytokines and activates the JAK2/STAT3 pathway, resulting in the upregulation of transcription factor C/EBPβ.

Neonatal Nicotine Exposure Primes Midbrain Neurons to a Dopaminergic Phenotype and Increases Adult Drug Consumption.

Background: Nicotine intake induces addiction through neuroplasticity of the reward circuitry, altering the activity of dopaminergic neurons of the ventral tegmental area. Prior work demonstrated that altered circuit activity can change neurotransmitter expression in the developing and adult brain. Here we investigated the effects of neonatal nicotine exposure on the dopaminergic system and nicotine consumption in adulthood.

Delta-secretase-cleaved Tau antagonizes TrkB neurotrophic signalings, mediating Alzheimer's disease pathologies.

BDNF, an essential trophic factor implicated in synaptic plasticity and neuronal survival, is reduced in Alzheimer's disease (AD). BDNF deficiency's association with Tau pathology in AD is well documented. However, the molecular mechanisms accounting for these events remain incompletely understood.

Genetic silencing of striatal CaV1.3 prevents and ameliorates levodopa dyskinesia.

Background: Levodopa-induced dyskinesias are an often debilitating side effect of levodopa therapy in Parkinson's disease. Although up to 90% of individuals with PD develop this side effect, uniformly effective and well-tolerated antidyskinetic treatment remains a significant unmet need. The pathognomonic loss of striatal dopamine in PD results in dysregulation and disinhibition of striatal CaV1.

Multimodal Production of Adeno-Associated Virus.

Adeno-associated virus (AAV) is an increasingly popular tool in the research laboratory, and use of this viral vector clinically is occurring at an accelerated pace. Nevertheless, despite its popularity, AAV is a relatively cumbersome virus to produce; however, significant efforts have been invested to develop, optimize, and simplify methodology that allows the generation of high-quality AAV with significantly increased production yields. Here we describe multiple modalities for production and purification of AAV particles produced in HEK293 cell cultures using an iodixanol density gradient.

Design and Assembly of CRISPR/Cas9 Lentiviral and rAAV Vectors for Targeted Genome Editing.

Clustered regularly interspaced short palindromic repeat (CRISPR/Cas) system has emerged as an extremely useful tool for biological research and as a potential technology for gene therapy approaches. CRISPR/Cas mediated genome editing can be used to easily and efficiently modify endogenous genes in a large variety of cells and organisms. Furthermore, a modified version of the Cas9 nuclease has been developed that can be used for regulation of endogenous gene expression and labeling of genomic loci, among other applications.

Basic Concepts in Viral Vector-Mediated Gene Therapy.

Today any researcher with the desire can easily purchase a viral vector. However, despite the availability of viral vectors themselves, the requisite knowledge that is absolutely essential to conducting a gene therapy experiment remains somewhat obscure and esoteric. To utilize viral vectors to their full potential, a large number of decisions must be made, in some instances prior to even obtaining the vector itself.

Regulation of dopamine neurotransmission from serotonergic neurons by ectopic expression of the dopamine D2 autoreceptor blocks levodopa-induced dyskinesia.

Levodopa-induced dyskinesias (LID) are a prevalent side effect of chronic treatment with levodopa (L-DOPA) for the motor symptoms of Parkinson's disease (PD). It has long been hypothesized that serotonergic neurons of the dorsal raphe nucleus (DRN) are capable of L-DOPA uptake and dysregulated release of dopamine (DA), and that this "false neurotransmission" phenomenon is a main contributor to LID development. Indeed, many preclinical studies have demonstrated LID management with serotonin receptor agonist treatment, but unfortunately, promising preclinical data has not been translated in large-scale clinical trials.

BDNF inhibits neurodegenerative disease-associated asparaginyl endopeptidase activity via phosphorylation by AKT.

AEP is an age-dependent lysosomal asparaginyl endopeptidase that cleaves numerous substrates including tau and α-synuclein and mediates their pathological roles in neurodegenerative diseases. However, the molecular mechanism regulating this critical protease remains incompletely understood. Here, we show that Akt phosphorylates AEP on residue T322 upon brain-derived neurotrophic factor (BDNF) treatment and triggers its lysosomal translocation and inactivation.

α-Synuclein stimulation of monoamine oxidase-B and legumain protease mediates the pathology of Parkinson's disease.

Dopaminergic neurodegeneration in Parkinson's disease (PD) is associated with abnormal dopamine metabolism by MAO-B (monoamine oxidase-B) and intracellular α-Synuclein (α-Syn) aggregates, called the Lewy body. However, the molecular relationship between α-Syn and MAO-B remains unclear. Here, we show that α-Syn directly binds to MAO-B and stimulates its enzymatic activity, which triggers AEP (asparagine endopeptidase; legumain) activation and subsequent α-Syn cleavage at N103, leading to dopaminergic neurodegeneration.

C/EBPβ regulates delta-secretase expression and mediates pathogenesis in mouse models of Alzheimer's disease.

Delta-secretase cleaves both APP and Tau to mediate the formation of amyloid plaques and neurofibrillary tangle in Alzheimer's disease (AD). However, how aging contributes to an increase in delta-secretase expression and AD pathologies remains unclear. Here we show that a CCAAT-enhancer-binding protein (C/EBPβ), an inflammation-regulated transcription factor, acts as a key age-dependent effector elevating both delta-secretase (AEP) and inflammatory cytokines expression in mediating pathogenesis in AD mouse models.