Roles of neuronal lysosomes in the etiology of Parkinson's disease.

Therapeutic progress in neurodegenerative conditions such as Parkinson's disease has been hampered by a lack of detailed knowledge of its molecular etiology. The advancements in genetics and genomics have provided fundamental insights into specific protein players and the cellular processes involved in the onset of disease. In this respect, the autophagy-lysosome system has emerged in recent years as a strong point of convergence for genetics, genomics, and pathologic indications, spanning both familial and idiopathic Parkinson's disease.

The small GTPase Rit2 modulates LRRK2 kinase activity, is required for lysosomal function and protects against alpha-synuclein neuropathology.

In Parkinson's disease (PD) misfolded alpha-synuclein (aSyn) accumulates in the substantia nigra, where dopaminergic neurons are progressively lost. The mechanisms underlying aSyn pathology are still unclear, but they are hypothesized to involve the autophagy-lysosome pathway (ALP). LRRK2 mutations are a major cause of familial and sporadic PD, and LRRK2 kinase activity has been shown to be involved in pS129-aSyn inclusion modulation.

Lysosomal Pathogenesis of Parkinson's Disease: Insights From LRRK2 and GBA1 Rodent Models.

The discovery of mutations in LRRK2 and GBA1 that are linked to Parkinson's disease provided further evidence that autophagy and lysosome pathways are likely implicated in the pathogenic process. Their protein products are important regulators of lysosome function. LRRK2 has kinase-dependent effects on lysosome activity, autophagic efficacy and lysosomal Ca signaling.

Modeling Parkinson's disease in LRRK2 mice: focus on synaptic dysfunction and the autophagy-lysosomal pathway.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are associated with familial and sporadic forms of Parkinson's disease (PD), for which the LRRK2 locus itself represents a risk factor. Idiopathic and LRRK2-related PD share the main clinical and neuropathological features, thus animals harboring the most common LRRK2 mutations, i.e.

LRRK2 along the Golgi and lysosome connection: a jamming situation.

Parkinson's disease (PD) is an age-related neurodegenerative disorder, clinically characterized by bradykinesia, rigidity, and resting tremor. Leucine-Rich Repeat Kinase 2 (LRRK2) is a large, multidomain protein containing two enzymatic domains. Missense mutations in its coding sequence are amongst the most common causes of familial PD.

Neuron-autonomous susceptibility to induced synuclein aggregation is exacerbated by endogenous mutations and ameliorated by genetic knock-out.

Neuronal aggregates containing α-synuclein are a pathological hallmark of several degenerative diseases; including Parkinson's disease, Parkinson's disease with dementia and dementia with Lewy bodies. Understanding the process of α-synuclein aggregation, and discovering means of preventing it, may help guide therapeutic strategy and drug design. Recent advances provide tools to induce α-synuclein aggregation in neuronal cultures.

Alpha-Synuclein and LRRK2 in Synaptic Autophagy: Linking Early Dysfunction to Late-Stage Pathology in Parkinson's Disease.

The lack of effective disease-modifying strategies is the major unmet clinical need in Parkinson´s disease. Several experimental approaches have attempted to validate cellular targets and processes. Of these, autophagy has received considerable attention in the last 20 years due to its involvement in the clearance of pathologic protein aggregates and maintenance of neuronal homeostasis.

Application of CRISPR/Cas9 editing and digital droplet PCR in human iPSCs to generate novel knock-in reporter lines to visualize dopaminergic neurons.

Human induced pluripotent stem cells (hiPSCs) have become indispensable for disease modelling. They are an important resource to access patient cells harbouring disease-causing mutations. Derivation of midbrain dopaminergic (DAergic) neurons from hiPSCs of PD patients represents the only option to model physiological processes in a cell type that is not otherwise accessible from human patients.

A new hypothesis for Parkinson's disease pathogenesis: GTPase-p38 MAPK signaling and autophagy as convergence points of etiology and genomics.

The combination of genetics and genomics in Parkinson´s disease has recently begun to unveil molecular mechanisms possibly underlying disease onset and progression. In particular, catabolic processes such as autophagy have been increasingly gaining relevance as post-mortem evidence and experimental models suggested a participation in neurodegeneration and alpha-synuclein Lewy body pathology. In addition, familial Parkinson´s disease linked to LRRK2 and alpha-synuclein provided stronger correlation between etiology and alterations in autophagy.

Cryopreservation of Primary Mouse Neurons: The Benefit of Neurostore Cryoprotective Medium.

Primary neuronal culture from rodents is a well-established model to investigate cellular neurobiology . However, for this purpose cell cultures need to be generated expressly, requiring extensive animal handling. Furthermore, often the preparation of fresh culture generates an excess of cells that are ultimately wasted.

Initial elevations in glutamate and dopamine neurotransmission decline with age, as does exploratory behavior, in LRRK2 G2019S knock-in mice.

LRRK2 mutations produce end-stage Parkinson's disease (PD) with reduced nigrostriatal dopamine, whereas, asymptomatic carriers have increased dopamine turnover and altered brain connectivity. LRRK2 pathophysiology remains unclear, but reduced dopamine and mitochondrial abnormalities occur in aged G2019S mutant knock-in (GKI) mice. Conversely, cultured GKI neurons exhibit increased synaptic transmission.

CADPS2 gene expression is oppositely regulated by LRRK2 and alpha-synuclein.

The Ca-dependent activator protein for secretion 2 (CADPS2) is a member of the CAPS/CADPS protein family that plays crucial roles in synaptic vesicle dynamics. Genomic variability in the CADPS2 gene has been associated to autism spectrum disorders and Alzheimer's disease, both characterized by altered neurotransmission. Biological evidence also linked CADPS2 to Parkinson's disease (PD), as a disease-causing mutation in leucine-rich repeat kinase 2 (LRRK2) was reported to increase CADPS2 gene and protein expression.

LRRK2 mouse models: dissecting the behavior, striatal neurochemistry and neurophysiology of PD pathogenesis.

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of familial Parkinson's disease (PD), resembling the sporadic disorder. Intensive effort has been directed toward LRRK2 mouse modeling and investigation, aimed at reproducing the human disease to inform mechanistic studies of pathogenesis and design of neuroprotective therapies. The physiological function of LRRK2 is still under exploration, but a clear role in striatal neurophysiology and animal behavior has emerged.

Elevated levels of alpha-synuclein blunt cellular signal transduction downstream of Gq protein-coupled receptors.

Alpha-synuclein is central to Parkinson's disease pathogenesis and pathology, however its precise functions are still unclear. It has been shown to bind both PLCβ1 and MAPKs, but how this property influences the downstream signaling of Gq protein-coupled receptors has not been elucidated. Here we show that recombinant expression of alpha-synuclein in human neuroblastoma cells enhances cellular levels of PLCβ1 but blunts its signaling pathway, preventing the agonist-dependent rise of cytoplasmic Ca.

Insights from late-onset familial parkinsonism on the pathogenesis of idiopathic Parkinson's disease.

Disease-modifying therapies that slow or halt the progression of Parkinson's disease are an unmet clinical need. Many hypotheses have been put forward to explain the pathogenesis of the disease, but none has led to the development of disease-modifying drugs. Here we focus on familial forms of late-onset parkinsonism that most closely resemble idiopathic Parkinson's disease and present a synthesis of emerging molecular advances.

Chronic and acute LRRK2 silencing has no long-term behavioral effects, whereas wild-type and mutant LRRK2 overexpression induce motor and cognitive deficits and altered regulation of dopamine release.

Introduction: Germline silencing of the PD-related protein LRRK2 does not alter glutamate or dopamine release in adult mice, but some exploratory abnormalities have been reported with ageing. Contrastingly, high levels of human LRRK2 cause locomotor alterations and cognitive deficits accompanied by reduced striatal dopamine levels, with the latter also observed in G2019S mutant mice. Comparative cognitive and motor behavioral testing of LRRK2 KO, overexpressor and mutant overexpressor mice has not previously been reported.

LRRK2 overexpression alters glutamatergic presynaptic plasticity, striatal dopamine tone, postsynaptic signal transduction, motor activity and memory.

Mutations in leucine-rich repeat kinase 2 (Lrrk2) are the most common genetic cause of Parkinson's disease (PD), a neurodegenerative disorder affecting 1-2% of those >65 years old. The neurophysiology of LRRK2 remains largely elusive, although protein loss suggests a role in glutamatergic synapse transmission and overexpression studies show altered dopamine release in aged mice. We show that glutamate transmission is unaltered onto striatal projection neurons (SPNs) of adult LRRK2 knockout mice and that adult animals exhibit no detectable cognitive or motor deficits.

Synaptic function is modulated by LRRK2 and glutamate release is increased in cortical neurons of G2019S LRRK2 knock-in mice.

Mutations in Leucine-Rich Repeat Kinase-2 (LRRK2) result in familial Parkinson's disease and the G2019S mutation alone accounts for up to 30% in some ethnicities. Despite this, the function of LRRK2 is largely undetermined although evidence suggests roles in phosphorylation, protein interactions, autophagy and endocytosis. Emerging reports link loss of LRRK2 to altered synaptic transmission, but the effects of the G2019S mutation upon synaptic release in mammalian neurons are unknown.

Stimulation of δ opioid receptor and blockade of nociceptin/orphanin FQ receptor synergistically attenuate parkinsonism.

δ opioid peptide (DOP) receptors are considered a therapeutic target in Parkinson's disease, although the use of DOP agonists may be limited by side effects, including convulsions. To circumvent this issue, we evaluated whether blockade of nociceptin/orphanin FQ (N/OFQ) tone potentiated the antiparkinsonian effects of DOP agonists, thus allowing for reduction of their dosage. Systemic administration of the N/OFQ receptor (NOP) antagonist J-113397 [(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H benzimidazol-2-one] and the DOP receptor agonist SNC-80 [(+)-4-[(αR)-α-(2S,5R)-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxy-benzyl]-N-N-diethylbenzamide] revealed synergistic attenuation of motor deficits in 6-hydroxydopamine hemilesioned rats and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice.

Behavioral deficits and striatal DA signaling in LRRK2 p.G2019S transgenic rats: a multimodal investigation including PET neuroimaging.

Background: A major risk-factor for developing Parkinson's disease (PD) is genetic variability in leucine-rich repeat kinase 2 (LRRK2), most notably the p.G2019S mutation. Examination of the effects of this mutation is necessary to determine the etiology of PD and to guide therapeutic development.

Memory and synaptic deficits in Hip14/DHHC17 knockout mice.

Palmitoylation of neurotransmitter receptors and associated scaffold proteins regulates their membrane association in a rapid, reversible, and activity-dependent fashion. This makes palmitoylation an attractive candidate as a key regulator of the fast, reversible, and activity-dependent insertion of synaptic proteins required during the induction and expression of long-term plasticity. Here we describe that the constitutive loss of huntingtin interacting protein 14 (Hip14, also known as DHHC17), a single member of the broad palmitoyl acyltransferase (PAT) family, produces marked alterations in synaptic function in varied brain regions and significantly impairs hippocampal memory and synaptic plasticity.

DNAJC13 mutations in Parkinson disease.

A Saskatchewan multi-incident family was clinically characterized with Parkinson disease (PD) and Lewy body pathology. PD segregates as an autosomal-dominant trait, which could not be ascribed to any known mutation. DNA from three affected members was subjected to exome sequencing.