Downregulation of eEF1A/EFT3-4 Enhances Dopaminergic Neurodegeneration After 6-OHDA Exposure in C. elegans Model

2,4,6-trinitrotoluene induces neurotoxicity by affecting the G protein pathways in Caenorhabditis elegans

2,4,6-trinitrotoluene (TNT) is a chemical widely used to make explosives, and its use of residues can lead to potential threats to both ecosystems and human health. A thorough understanding of the various toxic effects of TNT is essential for developing effective environmental protection and health safety measures. Thus, we employed Caenorhabditis elegans (C. elegans), a typical model organism, to explore the neurotoxic effects of TNT and the signaling pathways involved. The results showed that neurotoxicity induced by 10-100ng/mL TNT was manifested in reduced behavioral capacity (head thrashes, body bends, and pharyngeal pumping rates), and inhibition of foraging behavior and ethanol avoidance behavior. Using fluorescence-labeled transgenic nematodes, it was found that TNT damaged dopaminergic and cholinergic neurons, which resulted in a significant decrease in the release of neurotransmitters and the expression of associated genes (dat-1 and unc-17). We studied the role of G protein signaling pathways and discovered that the related genes (egl-30, gsa-1, goa-1, and unc-13) were significantly down-regulated, resulting in reduced acetylcholine release, which in turn corresponded to the observed behavioral abnormality and damaged neurons in the worms. This study shed light on TNT's neurotoxic mechanisms and associated health risks.

Neuroprotective Effect of Withaferin Derivatives toward MPP+ and 6-OHDA Toxicity to Dopaminergic Neurons

Parkinson's disease is a neurodegenerative proteinopathy that primarily affects mesencephalic dopaminergic neurons. This dopaminergic depletion can be phenotypically reproduced in various experimental models through the administration of two neurotoxins: N-methyl-4-phenylpyridinium (MPP+) and 6-hydroxydopamine (6-OHDA). The mechanisms underlying the cell death processes induced by these toxins remain a subject of debate. In this context, studies suggest that oxidative-stress-related processes may contribute to the dysfunction and death of dopaminergic neurons. Therefore, investigating pharmacological compounds that can counteract these processes remains crucial for developing therapeutic strategies targeting these neuropathological mechanisms. Withania somnifera (L.) Dunal, commonly known as ashwagandha, is a plant whose roots are used in Ayurvedic medicine to treat various ailments, including those affecting the central nervous system. The active compound Withaferin-A (WFA), a steroid lactone from the withanolide group, is reported to possess antioxidant properties. In this study, we explored the potential neuroprotective effects of WFA and two of its molecular derivatives, cr-591 and cr-777, which contain, respectively, an additional cysteine or glutathione chemical group, known for their antiradical properties. We demonstrated that WFA and its two derivatives, cr-591 and cr-777, protect the integrity and function of dopaminergic neurons exposed to the neurotoxins MPP+ and 6-OHDA both in vitro, using primary mesencephalic neuron cultures from rodents, and in vivo, using the nematode Caenorhabditis elegans.

Dopaminergic neuronal regulation determines innate immunity of Caenorhabditis elegans during Klebsiella aerogenes infection

The innate immune signals are the front line of host defense against bacterial pathogens. Pathogen-induced harmful effects, such as reduced neuronal signals to the intestine, affect the host's food sensing and dwelling behavior. Here, we report that dopamine and kpc-1 signals control the intestinal innate immune responses through the p38/PMK-1 MAPK signaling pathway in C. elegans. K. aerogenes infection in C. elegans affects the food-dwelling behavior, which depends on dopamine regulation. The absence of the dopamine receptor (dop-1) and transporter (dat-1) increases attraction to the pathogen instead of avoidance. The K. aerogenes infection affects age-1 regulation through the furin-like proprotein convertase (kpc-1); the absence of kpc-1 affects environment-dependent dauer formation. In contrast, the dop-1 mutation antagonistically regulates intestinal immune regulation, while the kpc-1 mutation partially regulates the p38/PMK-1 MAPK pathway. Our findings indicate that dopamine and kpc-1signaling from the nervous system control intestinal immunity in an antagonistic and agonistic manner, respectively.

Insulin and IGF-1 extend the lifespan of Caenorhabditis elegans by inhibiting insulin/insulin-like signaling and mTOR signaling pathways: C. elegans - Focused cancer research

The mutations in Caenorhabditis elegans (C. elegans) that extend lifespan slow down aging by interfering with several signaling pathways, including the insulin/IGF-1 signaling (IIS) pathway, AMP-activated protein kinase (AMPK), and mechanistic target of rapamycin (mTOR). The tumor suppressor pRb (retinoblastoma protein) is believed to be involved in almost all human cancers. Lin-35, the C. elegans orthologue of the tumor suppressor pRb, was included in the study to explore the effects of insulin and IGF-1 because it has been linked to cancer-related pRb function in mammals and exhibits a tumor suppressor effect by inhibiting mTOR or IIS signaling. According to our results, IGF-1 or insulin increased the lifespan of lin-35 worms compared to N2 worms by increasing fertilization efficiency, also causing a significant increase in body size. It was concluded that the expression of daf-2 and rsks-1 decreased after insulin or IGF-1 administration, thus extending the lifespan of C. elegans lin-35 worms through both IIS and mTOR-dependent mechanisms. This suggests that it was mediated by the combined effect of the TOR and IIS pathways. These results, especially obtained in cancer-associated mutant lin-35 worms, will be useful in elucidating the C. elegans cancer model in the future.

eEF1α2 is required for actin cytoskeleton homeostasis in the aging muscle

The translation elongation factor eEF1α (eukaryotic elongation factor 1α) mediates mRNA translation by delivering aminoacyl-tRNAs to ribosomes. eEF1α also has other reported roles, including the regulation of actin dynamics. However, these distinct roles of eEF1α are often challenging to uncouple and remain poorly understood in aging metazoan tissues. The genomes of mammals and Drosophila encode two eEF1α paralogs, with eEF1α1 expressed ubiquitously and eEF1α2 expression more limited to neurons and muscle cells. Here, we report that eEF1α2 plays a unique role in maintaining myofibril homeostasis during aging in Drosophila. Specifically, we generated an eEF1α2 null allele, which was viable and showed two distinct muscle phenotypes. In young flies, the mutants had thinner myofibrils in indirect flight muscles that could be rescued by expressing eEF1α1. With aging, the muscles of the mutant flies began showing abnormal distribution of actin and myosin in muscles, but without a change in actin and myosin protein levels. This age-related phenotype could not be rescued by eEF1α1 overexpression. These findings support an unconventional role of Drosophila eEF1α2 in age-related homeostasis of muscle myofibers.

eEF1A1 regulates the expression and alternative splicing of genes associated with Parkinson's disease in U251 cells

BACKGROUND

Eukaryotic elongation factor 1A1 (eEF1A1) is an RNA-binding protein that is associated with PARK2 activity in cells, suggesting a possible role in Parkinson's disease (PD).

OBJECTIVE

To clear whether eEF1A1 plays a role in PD through transcriptional or posttranscriptional regulation.

METHODS

The GSE68719 dataset was downloaded from the GEO database, and the RNA-seq data of all brain tissue autopsies were obtained from 29 PD patients and 44 neurologically normal control subjects. To inhibit eEF1A1 from being expressed in U251 cells, siRNA was transfected into those cells, and RNA-seq high-throughput sequencing was used to determine the differentially expressed genes (DEGs) and differentially alternative splicing events (ASEs) resulting from eEF1A1 knockdown.

RESULTS

eEF1A1 was significantly overexpressed in PD brain tissue in the BA9 area. GO and KEGG enrichment analyses revealed that eEF1A1 knockdown significantly upregulated the expression of the genes CXCL10, NGF, PTX3, IL6, ST6GALNAC3, NUPR1, TNFRSF21, and CXCL2 and upregulated the alternative splicing of the genes ACOT7, DDX10, SHMT2, MYEF2, and NDUFAF5. These genes were enriched in pathways related to PD pathogenesis, such as apoptosis, inflammatory response, and mitochondrial dysfunction.

CONCLUSION

The results suggesting that eEF1A1 involved in the development of PD by regulating the differential expression and alternative splicing of genes, providing a theoretical basis for subsequent research.

The eEF1A protein in cancer: Clinical significance, oncogenic mechanisms, and targeted therapeutic strategies

Eukaryotic elongation factor 1A (eEF1A) is among the most abundant proteins in eukaryotic cells. Evolutionarily conserved across species, eEF1A is in charge of translation elongation for protein biosynthesis as well as a plethora of non-translational moonlighting functions for cellular homeostasis. In malignant cells, however, eEF1A becomes a pleiotropic driver of cancer progression via a broad diversity of pathways, which are not limited to hyperactive translational output. In the past decades, mounting studies have demonstrated the causal link between eEF1A and carcinogenesis, gaining deeper insights into its multifaceted mechanisms and corroborating its value as a prognostic marker in various cancers. On the other hand, an increasing number of natural and synthetic compounds were discovered as anticancer eEF1A-targeting inhibitors. Among them, plitidepsin was approved for the treatment of multiple myeloma whereas metarrestin was currently under clinical development. Despite significant achievements in these two interrelated fields, hitherto there lacks a systematic examination of the eEF1A protein in the context of cancer research. Therefore, the present work aims to delineate its clinical implications, molecular oncogenic mechanisms, and targeted therapeutic strategies as reflected in the ever expanding body of literature, so as to deepen mechanistic understanding of eEF1A-involved tumorigenesis and inspire the development of eEF1A-targeted chemotherapeutics and biologics.

Potential Therapeutic Effects of Policosanol from Insect Wax on Caenorhabditis elegans Models of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. The standard treatments for PD focus on symptom relief rather than attempting to address the underlying degenerative processes completely. This study aimed to evaluate the potential therapeutic effects of policosanol derived from insect wax (PIW) by investigating improvements in disease symptoms represented in Caenorhabditis elegans models of PD. For our assessments, we used the following three models: NL5901, which is a transgenic model for α-synuclein aggregation; wild-type N2 induced with 6-hydroxydopamine (6-OHDA); and 6-OHDA-induced BZ555 as a model for loss of dopaminergic neurons (DNs). Specifically, we examined the effects of PIW treatment on α-synuclein aggregation, the loss of DNs, lipid abundance, and the lifespan of treated organisms. Further, we examined treatment-related changes in the levels of reactive oxygen species (ROS), malondialdehyde (MDA), adenosine triphosphate (ATP), glutathione S-transferase (GST), and superoxide dismutase (SOD), as well as the mRNA production profiles of relevant genes. A 10 µg/mL dose of PIW reduced the aggregation of α-synuclein in NL5901 and suppressed the loss of DNs in 6-OHDA-induced BZ555. Overall, PIW treatment decreased ROS and MDA levels, restored lipid abundance, and prolonged the lifespans of worms in all the three models, which may be associated with changes in the expression profiles of genes related to cell survival and oxidative stress response pathways. Our findings show that PIW alleviated the symptoms of PD in these models, possibly by regulating the stress responses initiated by injuries such as α-synuclein aggregation or 6-OHDA treatment.

The Potential Regulation of A-to-I RNA Editing on Genes in Parkinson's Disease

Parkinson's disease (PD) is characterized by dopaminergic neurodegeneration and an abnormal accumulation of α-synuclein aggregates. A number of genetic factors have been shown to increase the risk of PD. Exploring the underlying molecular mechanisms that mediate PD's transcriptomic diversity can help us understand neurodegenerative pathogenesis. In this study, we identified 9897 A-to-I RNA editing events associated with 6286 genes across 372 PD patients. Of them, 72 RNA editing events altered miRNA binding sites and this may directly affect miRNA regulations of their host genes. However, RNA editing effects on the miRNA regulation of genes are more complex. They can (1) abolish existing miRNA binding sites, which allows miRNAs to regulate other genes; (2) create new miRNA binding sites that may sequester miRNAs from regulating other genes; or (3) occur in the miRNA seed regions and change their targets. The first two processes are also referred to as miRNA competitive binding. In our study, we found 8 RNA editing events that may alter the expression of 1146 other genes via miRNA competition. We also found one RNA editing event that modified a miRNA seed region, which was predicted to disturb the regulation of four genes. Considering the PD-related functions of the affected genes, 25 A-to-I RNA editing biomarkers for PD are proposed, including the 3 editing events in the EIF2AK2, APOL6, and miR-4477b seed regions. These biomarkers may alter the miRNA regulation of 133 PD-related genes. All these analyses reveal the potential mechanisms and regulations of RNA editing in PD pathogenesis.

The eEF1 family of mammalian translation elongation factors

The eEF1 family of mammalian translation elongation factors is comprised of the two variants of eEF1A (eEF1A1 and eEF1A2), and the eEF1B complex. The latter consists of eEF1Bα, eEF1Bβ, and eEF1Bγ subunits. The two eEF1A variants have similar translation activity but may differ with respect to their secondary, "moonlighting" functions. This variability is underlined by the difference in the spatial organization of eEF1A1 and eEF1A2, and also possibly by the differences in their post-translational modifications. Here, we review the data on the spatial organization and post-translation modifications of eEF1A1 and eEF1A2, and provide examples of their involvement in various processes in addition to translation. We also describe the structural models of eEF1B subunits, their organization in the subcomplexes, and the trimeric model of the entire eEF1B complex. We discuss the functional consequences of such an assembly into a complex as well as the involvement of individual subunits in non-translational processes.

Para-Hydroxybenzyl Alcohol Delays the Progression of Neurodegenerative Diseases in Models of Caenorhabditis elegans through Activating Multiple Cellular Protective Pathways

The traditional Chinese medicine Gastrodia elata (commonly called “Tianma” in Chinese) has been widely used in the treatment of rheumatism, epilepsy, paralysis, headache, and dizziness. Phenolic compounds, such as gastrodin, para-hydroxybenzyl alcohol (HBA), p-hydroxybenzaldehyde, and vanillin are the main bioactive components isolated from Gastrodia elata. These compounds not only are structurally related but also share similar pharmacological activities, such as antioxidative and anti-inflammatory activities, and effects on the treatment of aging-related diseases. Here, we investigated the effect of para-hydroxybenzyl alcohol (HBA) on neurodegenerative diseases and aging in models of Caenorhabditis elegans (C. elegans). Our results showed that HBA effectively delayed the progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease in models of C. elegans. In addition, HBA could increase the average lifespan of N2 worms by more than 25% and significantly improve the age-related physiological functions of worms. Moreover, HBA improved the survival rate of worms under stresses of oxidation, heat, and pathogenic bacteria. Further mechanistic investigation revealed that HBA could activate FOXO/DAF-16 and SKN-1 to regulate antioxidative and xenobiotic metabolism pathway. HBA could also activate HSF-1 to regulate proteostasis maintenance pathway, mitochondrial unfolded stress response, endoplasmic stress response and autophagy pathways. The above results suggest that HBA activated multiple cellular protective pathways to increase stress resistance and protect against aging and aging-related diseases. Overall, our study indicates that HBA is a potential candidate for future development of antiaging pharmaceutical application.

Dysregulation of Human Somatic piRNA Expression in Parkinson's Disease Subtypes and Stages

Piwi interacting RNAs (piRNAs) are small non-coding single-stranded RNA species 20–31 nucleotides in size generated from distinct loci. In germline tissues, piRNAs are amplified via a “ping-pong cycle” to produce secondary piRNAs, which act in transposon silencing. In contrast, the role of somatic-derived piRNAs remains obscure. Here, we investigated the identity and distribution of piRNAs in human somatic tissues to determine their function and potential role in Parkinson’s disease (PD). Human datasets were curated from the Gene Expression Omnibus (GEO) database and a workflow was developed to identify piRNAs, which revealed 902 somatic piRNAs of which 527 were expressed in the brain. These were mainly derived from chromosomes 1, 11, and 19 compared to the germline tissues, which were from 15 and 19. Approximately 20% of somatic piRNAs mapped to transposon 3′ untranslated regions (UTRs), but a large proportion were sensed to the transcript in contrast to germline piRNAs. Gene set enrichment analysis suggested that somatic piRNAs function in neurodegenerative disease. piRNAs undergo dysregulation in different PD subtypes (PD and Parkinson’s disease dementia (PDD)) and stages (premotor and motor). piR-has-92056, piR-hsa-150797, piR-hsa-347751, piR-hsa-1909905, piR-hsa-2476630, and piR-hsa-2834636 from blood small extracellular vesicles were identified as novel biomarkers for PD diagnosis using a sparse partial least square discriminant analysis (sPLS-DA) (accuracy: 92%, AUC = 0.89). This study highlights a role for piRNAs in PD and provides tools for novel biomarker development.

Chemically induced models of Parkinson's disease

Environmental toxins are harmful substances detrimental to humans. Constant exposure to these fatal neurotoxins can cause various neurodegenerative disorders. Although poisonous, specific neurotoxins at optimal concentrations mimic the clinical features of neurodegenerative diseases in several animal models. Such chemically-induced model systems are beneficial in deciphering the molecular mechanisms of neurodegeneration and drug screening for these disorders. One such neurotoxin is 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a widely used chemical that recapitulates Parkinsonian features in various animal models. Apart from MPTP, other neurotoxins like 6-hydroxydopamine (6-OHDA), paraquat, rotenone also induce specific clinical features of Parkinson's disease in animal models. These chemically-induced Parkinson's disease models are playing a crucial role in understanding Parkinson's disease onset, pathology, and novel therapeutics. In this review, we provide a concise overview of various neurotoxins that can recapitulate Parkinsonian features in different in vivo and in vitro model systems specifically focusing on the different treatment methodologies of neurotoxins.

METTL14 promotes apoptosis of spinal cord neurons by inducing EEF1A2 m6A methylation in spinal cord injury

Spinal cord injury (SCI) is a devastating traumatic condition. METTL14-mediated m6A modification is associated with SCI. This study was intended to investigate the functional mechanism of RNA methyltransferase METTL14 in spinal cord neuron apoptosis during SCI. The SCI rat model was established, followed by evaluation of pathological conditions, apoptosis, and viability of spinal cord neurons. The neuronal function of primary cultured spinal motoneurons of rats was assessed after hypoxia/reoxygenation treatment. Expressions of EEF1A2, Akt/mTOR pathway-related proteins, inflammatory cytokines, and apoptosis-related proteins were detected. EEF1A2 was weakly expressed and Akt/mTOR pathway was inhibited in SCI rat models. Hypoxia/Reoxygenation decreased the viability of spinal cord neurons, promoted LDH release and neuronal apoptosis. EEF1A2 overexpression promoted the viability of spinal cord neurons, inhibited neuronal apoptosis, and decreased inflammatory cytokine levels. Silencing METTL14 inhibited m6A modification of EEF1A2 and increased EEF1A2 expression while METTL14 overexpression showed reverse results. EEF1A2 overexpression promoted viability and inhibited apoptosis of spinal cord neurons and inflammation by activating the Akt/mTOR pathway. In conclusion, silencing METTL14 repressed apoptosis of spinal cord neurons and attenuated SCI by inhibiting m6A modification of EEF1A2 and activating the Akt/mTOR pathway.

Diterpene glycosides from Holothuria scabra exert the α-synuclein degradation and neuroprotection against α-synuclein-Mediated neurodegeneration in C. elegans model

ETHNOPHARMACOLOGICAL RELEVANCE

Holothuria (Metriatyla) scabra Jaeger (H. scabra), sea cucumber, is the marine organism that has been used as traditional food and medicine to gain the health benefits since ancient time. Although our recent studies have shown that crude extracts from H. scabra exhibited neuroprotective effects against Parkinson's disease (PD), the underlying mechanisms and bioactive compounds are still unknown.

AIM OF THE STUDY

In the present study, we examined the efficacy of purified compounds from H. scabra and their underlying mechanism on α-synuclein degradation and neuroprotection against α-synuclein-mediated neurodegeneration in a transgenic Caenorhabditis elegans PD model.

MATERIAL AND METHODS

The H. scabra compounds (HSEA-P1 and P2) were purified and examined for their toxicity and optimal dose-range by food-clearance and lifespan assays. The α-synuclein degradation and neuroprotection against α-synuclein-mediated neurodegeneration were determined using transgenic C. elegans model, Punc-54::α-syn and Pdat-1:: α-syn; Pdat-1::GFP, respectively, and then further investigated by determining the behavioral assays including locomotion rate, basal slowing rate, ethanol avoidance, and area-restricted searching. The underlying mechanisms related to autophagy were clarified by quantitative PCR and RNAi experiments.

RESULTS

Our results showed that HSEA-P1 and HSEA-P2 significantly diminished α-synuclein accumulation, improved motility deficits, and recovered the shortened lifespan. Moreover, HSEA-P1 and HSEA-P2 significantly protected dopaminergic neurons from α-synuclein toxicity and alleviated dopamine-associated behavioral deficits, i.e., basal slowing, ethanol avoidance, and area-restricted searching. HSEA-P1 and HSEA-P2 also up-regulated autophagy-related genes, including beclin-1/bec-1, lc-3/lgg-1, and atg-7/atg-7. RNA interference (RNAi) of these genes in transgenic α-synuclein worms confirmed that lc-3/lgg-1 and atg-7/atg-7 were required for α-synuclein degradation and DAergic neuroprotection activities of HSEA-P1 and HSEA-P2. NMR and mass spectrometry analysis revealed that the HSEA-P1 and HSEA-P2 contained diterpene glycosides.

CONCLUSION

These findings indicate that diterpene glycosides extracted from H. scabra decreases α-synuclein accumulation and protects α-synuclein-mediated DAergic neuronal loss and its toxicities via lgg-1 and atg-7.

Exosomes Secreted by Adipose-Derived Stem Cells Following FK506 Stimulation Reduce Autophagy of Macrophages in Spine after Nerve Crush Injury

Macrophages emerge in the milieu around innervated neurons after nerve injuries. Following nerve injury, autophagy is induced in macrophages and affects the regulation of inflammatory responses. It is closely linked to neuroinflammation, while the immunosuppressive drug tacrolimus (FK506) enhances nerve regeneration following nerve crush injury and nerve allotransplantation with additional neuroprotective and neurotrophic functions. The combined use of FK506 and adipose-derived stem cells (ADSCs) was employed in cell therapy for organ transplantation and vascularized composite allotransplantation. This study aimed to investigate the topical application of exosomes secreted by ADSCs following FK506 treatment (ADSC-F-exo) to the injured nerve in a mouse model of sciatic nerve crush injury. Furthermore, isobaric tags for relative and absolute quantitation (iTRAQ) were used to profile the potential exosomal proteins involved in autophagy. Immunohistochemical analysis revealed that nerve crush injuries significantly induced autophagy in the dorsal root ganglia and dorsal horn of the spinal segments. Locally applied ADSC-F-exo significantly reduced autophagy of macrophages in the spinal segments after nerve crush injury. Proteomic analysis showed that of the 22 abundant exosomal proteins detected in ADSC-F-exo, heat shock protein family A member 8 (HSPA8) and eukaryotic translation elongation factor 1 alpha 1 (EEF1A1) are involved in exosome-mediated autophagy reduction.

Potentials of autophagy enhancing natural products in the treatment of Parkinson disease

Parkinson disease (PD) is a progressive neurodegenerative movement disorder characterized by motor and non-motor symptoms due to loss of striatal dopaminergic neurons and disruption of degradation signaling leading to the formation of Lewy bodies (aggregation of α-synuclein). Presently, there are no disease modifying therapy for PD despite improvement in the understanding of the disease pathogenesis. However, the drugs currently used in PD management provide symptomatic relieve for motor symptoms without significant improvement in non-motor complications, thus, a public health burden on caregivers and healthcare systems. There is therefore the need to discover disease modifying therapy with strong potential to halt the disease progression. Recent trend has shown that the dysfunction of lysosomal-autophagy pathway is highly implicated in PD pathology, hence, making autophagy a key player owing to its involvement in degradation and clearance of misfolded α-synuclein (a major hallmark in PD pathology). In this review, we described the current drugs/strategy in the management of PD including targeting the autophagy pathway as a novel approach that could serve as potential intervention for PD management. The discovery of small molecules or natural products capable of enhancing autophagy mechanism could be a promising strategy for PD treatment.

Potentials of autophagy enhancing natural products in the treatment of Parkinson disease

Parkinson disease (PD) is a progressive neurodegenerative movement disorder characterized by motor and non-motor symptoms due to loss of striatal dopaminergic neurons and disruption of degradation signaling leading to the formation of Lewy bodies (aggregation of α-synuclein). Presently, there are no disease modifying therapy for PD despite improvement in the understanding of the disease pathogenesis. However, the drugs currently used in PD management provide symptomatic relieve for motor symptoms without significant improvement in non-motor complications, thus, a public health burden on caregivers and healthcare systems. There is therefore the need to discover disease modifying therapy with strong potential to halt the disease progression. Recent trend has shown that the dysfunction of lysosomal-autophagy pathway is highly implicated in PD pathology, hence, making autophagy a key player owing to its involvement in degradation and clearance of misfolded α-synuclein (a major hallmark in PD pathology). In this review, we described the current drugs/strategy in the management of PD including targeting the autophagy pathway as a novel approach that could serve as potential intervention for PD management. The discovery of small molecules or natural products capable of enhancing autophagy mechanism could be a promising strategy for PD treatment.

Neurorescue Effects of Frondoside A and Ginsenoside Rg3 in C. elegans Model of Parkinson's Disease

Parkinson’s disease (PD) is a currently incurable neurodegenerative disorder characterized by the loss of dopaminergic (DAergic) neurons in the substantia nigra pars compacta and α-synuclein aggregation. Accumulated evidence indicates that the saponins, especially from ginseng, have neuroprotective effects against neurodegenerative disorders. Interestingly, saponin can also be found in marine organisms such as the sea cucumber, but little is known about its effect in neurodegenerative disease, including PD. In this study, we investigated the anti-Parkinson effects of frondoside A (FA) from Cucumaria frondosa and ginsenoside Rg3 (Rg3) from Panax notoginseng in C. elegans PD model. Both saponins were tested for toxicity and optimal concentration by food clearance assay and used to treat 6-OHDA-induced BZ555 and transgenic α-synuclein NL5901 strains in C. elegans. Treatment with FA and Rg3 significantly attenuated DAergic neurodegeneration induced by 6-OHDA in BZ555 strain, improved basal slowing rate, and prolonged lifespan in the 6-OHDA-induced wild-type strain with downregulation of the apoptosis mediators, egl-1 and ced-3, and upregulation of sod-3 and cat-2. Interestingly, only FA reduced α-synuclein aggregation, rescued lifespan in NL5901, and upregulated the protein degradation regulators, including ubh-4, hsf-1, hsp-16.1 and hsp-16.2. This study indicates that both FA and Rg3 possess beneficial effects in rescuing DAergic neurodegeneration in the 6-OHDA-induced C. elegans model through suppressing apoptosis mediators and stimulating antioxidant enzymes. In addition, FA could attenuate α-synuclein aggregation through the protein degradation process.