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

Bioinformatics-based identification of key candidate genes and signaling pathways in patients with Parkinson's disease and obstructive sleep apnea

OBJECTIVES

Existing evidence exhibits that obstructive sleep apnea (OSA) is a potential consequence of Parkinson's disease (PD) or a contributor to PD progression. This investigation aimed to detect potential critical genes and molecular mechanisms underlying interactions between PD and OSA through bioinformatics analyses.

METHODS

The Gene Expression Omnibus (GEO) database was employed to obtain the expression profiles GSE20163 and GSE135917. The identification of common genes connected to PD and OSA was performed utilizing weighted gene co-expression network analysis and the R 4.0.4 program. The Cytoscape program was utilized to generate a network of protein-protein interactions (PPI), and the CytoHubba plugin was utilized to detect hub genes. Subsequently, functional enrichment analyses of the hub genes were conducted. Markers with increased diagnostic values for PD and OSA were confirmed using the GEO datasets GSE8397 and GSE38792.

RESULTS

Typically, 57 genes that are common were identified in PD and OSA. Among these common genes, the top 10 hub genes in the PPI network were chosen. The verified datasets confirmed the presence of three important genes: CADPS, CHGA, and SCG3. Functional enrichment analysis revealed that these hub genes mostly participate in GABAergic synapses.

CONCLUSION

Our findings suggest that CADPS, CHGA, and SCG3 are key genes involved in molecular mechanisms underlying interactions between OSA and PD. Functional enrichment of hub genes indicated a link between GABAergic synapses and the shared pathogenesis of PD and OSA. These candidate genes and corresponding pathways offer novel insights regarding biological targets that underlie the transcriptional connection between OSA and PD.

Decreased levels of alpha synuclein in families with autism spectrum disorder and relationship between the disease severity

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorders that begin in early childhood. Mutations in α-synuclein (SNCA) gene have been shown to result in the accumulation of α-synuclein, which occurs in many neurodegenerative diseases. Our aim was to determine the changes in the expression profile and protein level of this gene by comparing the autistic children with their healthy siblings, their mothers and healthy controls in order to elucidate the possible contribution of the SNCA gene to the etiology of ASD. 50 autistic patients, their mothers, siblings and 25 healthy controls and their mothers were enrolled to determine SNCA gene expression and serum α-synuclein levels. It was determined that α-synuclein serum levels decreased in the autistic patients. Similarly, it was found that SNCA gene expression and serum α-synuclein levels were significantly decreased in the mothers of the patients. Significant negative correlation was observed between the SNCA gene and protein expression amounts in the 6-8 age of the patients. This family-based study is the first in the literature, with both gene expression and serum levels of α-synuclein. The relationship between ASD severity and α-synuclein level needs to be confirmed in larger-scale studies.

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. We observed selective downregulation of the novel PD risk factor RIT2 in vitro and in vivo. Rit2 overexpression in G2019S-LRRK2 cells rescued ALP abnormalities and diminished aSyn inclusions. In vivo, viral mediated overexpression of Rit2 operated neuroprotection against AAV-A53T-aSyn. Furthermore, Rit2 overexpression prevented the A53T-aSyn-dependent increase of LRRK2 kinase activity in vivo. On the other hand, reduction of Rit2 levels leads to defects in the ALP, similar to those induced by the G2019S-LRRK2 mutation. Our data indicate that Rit2 is required for correct lysosome function, inhibits overactive LRRK2 to ameliorate ALP impairment, and counteracts aSyn aggregation and related deficits. Targeting Rit2 could represent an effective strategy to combat neuropathology in familial and idiopathic PD.

Neurodegeneration cell per cell

The clinical definition of neurodegenerative diseases is based on symptoms that reflect terminal damage of specific brain regions. This is misleading as it tells little about the initial disease processes. Circuitry failures that underlie the clinical symptomatology are themselves preceded by clinically mostly silent, slowly progressing multicellular processes that trigger or are triggered by the accumulation of abnormally folded proteins such as Aβ, Tau, TDP-43, and α-synuclein, among others. Methodological advances in single-cell omics, combined with complex genetics and novel ways to model complex cellular interactions using induced pluripotent stem (iPS) cells, make it possible to analyze the early cellular phase of neurodegenerative disorders. This will revolutionize the way we study those diseases and will translate into novel diagnostics and cell-specific therapeutic targets, stopping these disorders in their early track before they cause difficult-to-reverse damage to the brain.

Homozygous CADPS2 Mutations Cause Neurodegenerative Disease with Lewy Body-like Pathology in Parrots

BACKGROUND

Several genetic models that recapitulate neurodegenerative features of Parkinson's disease (PD) exist, which have been largely based on genes discovered in monogenic PD families. However, spontaneous genetic mutations have not been linked to the pathological hallmarks of PD in non-human vertebrates.

OBJECTIVE

To describe the genetic and pathological findings of three Yellow-crowned parrot (Amazona ochrocepahala) siblings with a severe and rapidly progressive neurological phenotype.

METHODS

The phenotype of the three parrots included severe ataxia, rigidity, and tremor, while their parents were phenotypically normal. Tests to identify avian viral infections and brain imaging studies were all negative. Due to their severe impairment, they were all euthanized at age 3 months and their brains underwent neuropathological examination and proteasome activity assays. Whole genome sequencing (WGS) was performed on the three affected parrots and their parents.

RESULTS

The brains of affected parrots exhibited neuronal loss, spongiosis, and widespread Lewy body-like inclusions in many regions including the midbrain, basal ganglia, and neocortex. Proteasome activity was significantly reduced in these animals compared to a control (P < 0.05). WGS identified a single homozygous missense mutation (p.V559L) in a highly conserved amino acid within the pleckstrin homology (PH) domain of the calcium-dependent secretion activator 2 (CADPS2) gene.

CONCLUSIONS

Our data suggest that a homozygous mutation in the CADPS2 gene causes a severe neurodegenerative phenotype with Lewy body-like pathology in parrots. Although CADPS2 variants have not been reported to cause PD, further investigation of the gene might provide important insights into the pathophysiology of Lewy body disorders. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Molecular Pathways Involved in LRRK2-Linked Parkinson’s Disease: A Systematic Review

Parkinson’s disease is one of the most common neurodegenerative diseases affecting the ageing population, with a prevalence that has doubled over the last 30 years. As the mechanism of the disease is not fully elucidated, the current treatments are unable to effectively prevent neurodegeneration. Studies have found that mutations in Leucine-rich-repeat-kinase 2 (LRRK2) are the most common cause of familial Parkinson’s disease (PD). Moreover, aberrant (higher) LRRK2 kinase activity has an influence in idiopathic PD as well. Hence, the aim of this review is to categorize and synthesize current information related to LRRK2-linked PD and present the factors associated with LRRK2 that can be targeted therapeutically. A systematic review was conducted using the databases PubMed, Medline, SCOPUS, SAGE, and Cochrane (January 2016 to July 2021). Search terms included “Parkinson’s disease”, “mechanism”, “LRRK2”, and synonyms in various combinations. The search yielded a total of 988 abstracts for initial review, 80 of which met the inclusion criteria. Here, we emphasize molecular mechanisms revealed in recent in vivo and in vitro studies. By consolidating the recent updates in the field of LRRK2-linked PD, researchers can further evaluate targets for therapeutic application.

Improvement of behavioural pattern and alpha-synuclein levels in autism spectrum disorder after consumption of a beta-glucan food supplement in a randomised, parallel-group pilot clinical study

Background

Autism spectrum disorders (ASDs) are a wide range of behavioural disabilities for which there are no definite interventional modalities available. Remedial therapies remain the only option but with varying outcomes. We have evaluated the Childhood Autism Rating Scale (CARS) and alpha-synuclein levels in this parallel-group, multiple-arm pilot clinical study after supplementation with a biological response modifier beta-glucan food supplement (Nichi Glucan).

Methods

Six subjects with ASD (n=6) Gr. 1 underwent conventional treatment comprising remedial behavioural therapies and L-carnosine 500 mg per day, and 12 subjects (n=12) Gr. 2 underwent supplementation with the Nichi Glucan 0.5 g two times per day along with the conventional treatment.

Results

There was a significant decrease in the CARS score in all of the children of the Nichi Glucan Gr.2 compared with the control (p=0.034517). Plasma levels of alpha-synuclein were significantly higher in Gr. 2 (Nichi Glucan) than in the control group Gr. 1 (p=0.091701).

Conclusion

Improvement of the behavioural pattern CARS score and a correlating alpha-synuclein level, followed by a safe beta-glucan food supplement, warrants further research on other parameters, such as gut-microbiota evaluation, and relevant neuronal biomarkers which is likely to cast light on novel solutions.

Complementary Transcriptomic and Proteomic Analysis in the Substantia Nigra of Parkinson's Disease

Parkinson's disease (PD) is a disease that involves brain damage and is associated with neuroinflammation, mitochondrial damage, and cell aging. However, the pathogenic mechanism of PD is still unknown. Sequencing data and proteomic data can describe the fluctuation of molecular abundance in diseases at the mRNA level and protein level, respectively. In order to explore new targets in the pathogenesis of PD, the study analyzed molecular changes from the database by combining transcriptomic and proteomic analysis. Differentially expressed genes and differentially abundant proteins were summarized and analyzed. Enrichment and cluster analysis emphasized the importance of neurotransmitter release, mitochondrial damage, and vesicle transport. The molecular network revealed a subnetwork of 9 molecules related to SCNA and TH and revealed hub gene with differential expression at both mRNA and protein levels. It found that ACHE and CADPS could be used as new targets in PD, emphasizing that impaired nerve signal transmission and vesicle transport affect the pathogenesis of PD. Our research emphasized that the joint analysis and verification of transcriptomics and proteomics were devoted to understanding the comprehensive views and mechanism of pathogenesis in PD.

Kinase inhibition of G2019S-LRRK2 enhances autolysosome formation and function to reduce endogenous alpha-synuclein intracellular inclusions

The Parkinson's disease (PD)-associated kinase Leucine-Rich Repeat Kinase 2 (LRRK2) is a crucial modulator of the autophagy-lysosome pathway, but unclarity exists on the precise mechanics of its role and the direction of this modulation. In particular, LRRK2 is involved in the degradation of pathological alpha-synuclein, with pathogenic mutations precipitating neuropathology in cellular and animal models of PD, and a significant proportion of LRRK2 patients presenting Lewy neuropathology. Defects in autophagic processing and lysosomal degradation of alpha-synuclein have been postulated to underlie its accumulation and onset of neuropathology. Thus, it is critical to obtain a comprehensive knowledge on LRRK2-associated pathology. Here, we investigated a G2019S-LRRK2 recombinant cell line exhibiting accumulation of endogenous, phosphorylated alpha-synuclein. We found that G2019S-LRRK2 leads to accumulation of LC3 and abnormalities in lysosome morphology and proteolytic activity in a kinase-dependent fashion, but independent from constitutively active Rab10. Notably, LRRK2 inhibition was ineffective upon upstream blockade of autophagosome-lysosome fusion events, highlighting this step as critical for alpha-synuclein clearance.

A protective role for N-acylphosphatidylethanolamine phospholipase D in 6-OHDA-induced neurodegeneration

N-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) catalyzes the cleavage of membrane NAPEs into bioactive fatty-acid ethanolamides (FAEs). Along with this precursor role, NAPEs might also serve autonomous signaling functions. Here, we report that injections of 6-hydroxydopamine (6-OHDA) into the mouse striatum cause a local increase in NAPE and FAE levels, which precedes neuronal cell death. NAPE, but not FAE, accumulation is enhanced in mice lacking NAPE-PLD, which display a substantial reduction in 6-OHDA-induced neurotoxicity, as shown by increased survival of substantia nigra dopamine neurons, integrity of striatal dopaminergic fibers, and striatal dopamine metabolite content. Reduced damage is accompanied by attenuation of the motor response evoked by apomorphine. Furthermore, NAPE-PLD silencing protects cathecolamine-producing SH-SY5Y cells from 6-OHDA-induced reactive oxygen species formation, caspase-3 activation and death. Mechanistic studies in mice suggest the existence of multiple molecular contributors to the neuroprotective effects of NAPE-PLD deletion, including suppression of Rac1 activity and attenuated transcription of several genes (Cadps, Casp9, Egln1, Kcnj6, Spen, and Uchl1) implicated in dopamine neuron survival and/or Parkinson's disease. The findings point to a previously unrecognized role for NAPE-PLD in the regulation of dopamine neuron function, which may be linked to the control of NAPE homeostasis in membranes.

An Alternative Exon of CAPS2 Influences Catecholamine Loading into LDCVs of Chromaffin Cells

The calcium-dependent activator proteins for secretion (CAPS) are priming factors for synaptic and large dense-core vesicles (LDCVs), promoting their entry into and stabilizing the release-ready state. A modulatory role of CAPS in catecholamine loading of vesicles has been suggested. Although an influence of CAPS on monoamine transporter function and on vesicle acidification has been reported, a role of CAPS in vesicle loading is disputed. Using expression of naturally occurring splice variants of CAPS2 into chromaffin cells from CAPS1/CAPS2 double-deficient mice of both sexes, we show that an alternative exon of 40 aa is responsible for enhanced catecholamine loading of LDCVs in mouse chromaffin cells. The presence of this exon leads to increased activity of both vesicular monoamine transporters. Deletion of CAPS does not alter acidification of vesicles. Our results establish a splice-variant-dependent modulatory effect of CAPS on catecholamine content in LDCVs.SIGNIFICANCE STATEMENT The calcium activator protein for secretion (CAPS) promotes and stabilizes the entry of catecholamine-containing vesicles of the adrenal gland into a release-ready state. Expression of an alternatively spliced exon in CAPS leads to enhanced catecholamine content in chromaffin granules. This exon codes for 40 aa with a high proline content, consistent with an unstructured loop present in the portion of the molecule generally thought to be involved in vesicle priming. CAPS variants containing this exon promote serotonin uptake into Chinese hamster ovary cells expressing either vesicular monoamine transporter. Epigenetic tuning of CAPS variants may allow modulation of endocrine adrenaline and noradrenaline release. This mechanism may extend to monoamine release in central neurons or in the enteric nervous system.

Significant Changes in Plasma Alpha-Synuclein and Beta-Synuclein Levels in Male Children with Autism Spectrum Disorder

Alpha-synuclein (α-synuclein) and beta-synuclein (β-synuclein) are presynaptic proteins playing important roles in neuronal plasticity and synaptic vesicle regulation. To evaluate the association of these two proteins and autism spectrum disorder (ASD), we investigated the plasma α-synuclein and β-synuclein levels in 39 male children with ASD (2 subgroups: 25 autism and 14 pervasive developmental disorder-not otherwise specified (PDD-NOS)) comparing with 29 sex- and age-matched controls by using enzyme-linked immunosorbent assay (ELISA). We first determined the levels of these two proteins in the ASD subgroups and found that there were no significant differences in both plasma α-synuclein and β-synuclein levels in the autism and PDD-NOS groups. Thus, we could combine the 2 subgroups into one ASD group. Interestingly, the mean plasma α-synuclein level was significantly lower (P < 0.001) in the ASD children (10.82 ± 6.46 ng/mL) than in the controls (29.47 ± 18.62 ng/mL), while the mean plasma β-synuclein level in the ASD children (1344.19 ± 160.26 ng/mL) was significantly higher (P < 0.05) than in the controls (1219.16 ± 177.10 ng/mL). This is the first study examining the associations between α-synuclein and β-synuclein and male ASD patients. We found that alterations in the plasma α-synuclein and β-synuclein levels might be implicated in the association between synaptic abnormalities and ASD pathogenesis.