Cerebral Dopamine Neurotrophic Factor: A Potential Therapeutic Agent for Parkinson's Disease

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.

STAT4 targets KISS1 to inhibit the oxidative damage, inflammation and neuronal apoptosis in experimental PD models by inactivating the MAPK pathway

BACKGROUND

Oxidative stress and neuroinflammation are proven to play critical roles in the pathogenesis of Parkinson's disease (PD). As reported, patients with PD have lower level of STAT4 compared with healthy subjects. However, the biological functions and mechanisms of STAT4 in PD pathogenesis remain uncertain. This study aimed to investigate the roles and related mechanisms of STAT4 in PD development.

METHODS

The intraperitoneal injection of MPTP (20 mg/kg) dissolved in physiological saline was performed to mimic PD-like conditions in vivo. MPP + solution was prepared for cell model of PD. Cell viability was measured by CCK-8. Griess reaction was conducted to measure NO concentrations. The mRNA and protein levels were evaluated by RT-qPCR and western blotting. ROS generation was assessed by DCFH-DA. The levels of inflammatory cytokines were measured by ELISA. Cell apoptosis was examined by flow cytometry and western blotting. Moreover, the SH-SY5Y cells were treated with conditioned medium from LPS-stimulated microglia and subjected to CCK-8 assays and ELISA. Mechanistically, CHIP assays and luciferase reporter assays were performed to verify the binding relationship between KISS1 and STAT4. For in vivo analysis, the histological changes of midbrain tissues of mice were determined by hematoxylin and eosin staining. The expression of tyrosine hydroxylase (TH) was detected by immunohistochemistry staining. Iba-1 positive microglial cells in the striatum were assessed by immunofluorescence staining.

RESULTS

For in vitro analysis, STAT4 level was downregulated after MPP+ treatment, and STAT4 upregulation inhibited the oxidative damage, inflammation and apoptosis in SH-SY5Y cells. STAT4 bound at +215-228 region of KISS1, and KISS1 upregulation counteracted the protection of STAT4 upregulation against cell damage. Moreover, STAT4 upregulation inhibited cell viability loss and inflammation induced by conditioned medium from LPS-treated microglia, whereas KISS1 upregulation had the opposite effect. For in vivo analysis, the protective effects of STAT4 upregulation against inflammatory response, oxidative stress, dopaminergic neuronal loss and microglia activation were attenuated by KISS1 upregulation. Moreover, the inactivation of MAPK pathway caused by STAT4 upregulation was reversed by KISS1 upregulation, and MAPK inhibition attenuated the MPP+-induced inflammation, oxidative stress and apoptosis in SH-SY5Y cells.

CONCLUSION

STAT4 inhibits KISS1 to attenuate the oxidative damage, inflammation and neuronal apoptosis in PD by inactivating the MAPK pathway.

Cortistatin as a Novel Multimodal Therapy for the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a complex disorder characterized by the impairment of the dopaminergic nigrostriatal system. PD has duplicated its global burden in the last few years, becoming the leading neurological disability worldwide. Therefore, there is an urgent need to develop innovative approaches that target multifactorial underlying causes to potentially prevent or limit disease progression. Accumulating evidence suggests that neuroinflammatory responses may play a pivotal role in the neurodegenerative processes that occur during the development of PD. Cortistatin is a neuropeptide that has shown potent anti-inflammatory and immunoregulatory effects in preclinical models of autoimmune and neuroinflammatory disorders. The goal of this study was to explore the therapeutic potential of cortistatin in a well-established preclinical mouse model of PD induced by acute exposure to the neurotoxin 1-methil-4-phenyl1-1,2,3,6-tetrahydropyridine (MPTP). We observed that treatment with cortistatin mitigated the MPTP-induced loss of dopaminergic neurons in the substantia nigra and their connections to the striatum. Consequently, cortistatin administration improved the locomotor activity of animals intoxicated with MPTP. In addition, cortistatin diminished the presence and activation of glial cells in the affected brain regions of MPTP-treated mice, reduced the production of immune mediators, and promoted the expression of neurotrophic factors in the striatum. In an in vitro model of PD, treatment with cortistatin also demonstrated a reduction in the cell death of dopaminergic neurons that were exposed to the neurotoxin. Taken together, these findings suggest that cortistatin could emerge as a promising new therapeutic agent that combines anti-inflammatory and neuroprotective properties to regulate the progression of PD at multiple levels.

Aging-Related Protein Alterations in the Brain

Aging is an intrinsic aspect of an organism's life cycle and is characterized by progressive physiological decline and increased susceptibility to mortality. Many age-associated disorders, including neurological disorders, are most commonly linked with the aging process, such as Alzheimer's disease (AD). This review aims to provide a comprehensive overview of the effects of aging and AD on the molecular pathways and levels of different proteins in the brain, including metalloproteins, neurotrophic factors, amyloid proteins, and tau proteins. AD is caused by the aggregation of amyloid proteins in the brain. Factors such as metal ions, protein ligands, and the oligomerization state of amyloid precursor protein significantly influence the proteolytic processing of amyloid-β protein precursor (AβPP). Tau, a disordered cytosolic protein, serves as the principal microtubule-associated protein in mature neurons. AD patients exhibit decreased levels of nerve growth factor within their nervous systems and cerebrospinal fluid. Furthermore, a significant increase in brain-derived neurotrophic factor resulting from the neuroprotective effect of glial cell line-derived neurotrophic factor suggests that the synergistic action of these proteins plays a role in inhibiting neuronal degeneration and atrophy. The mechanism through which Aβ and AβPP govern Cu2+ transport and their influence on Cu2+ and other metal ion pools requires elucidation in future studies. A comprehensive understanding of the influence of aging and AD on molecular pathways and varying protein levels may hold the potential for the development of novel diagnostic and therapeutic methods for the treatment of AD.

Key Subdomains of Cerebral Dopamine Neurotrophic Factor Regulate Its Protective Function in 6-Hydroxydopamine-Lesioned PC12 Cells

Cerebral dopamine neurotrophic factor (CDNF) is a unique neurotrophic factor (NTF) that has shown significant neuroprotective and neurorestorative functions on midbrain dopaminergic neurons. The secondary structure of human CDNF protein contains eight α-helices. We previously found that two key helices, α1 and α7, regulated the intracellular trafficking and secretion of CDNF protein in different manners. The α1 mutation (M1) induced most CDNF proteins to reside in the endoplasmic reticulum and little be secreted extracellularly, while the α7 mutation (M7) caused the majority of CDNF proteins to be secreted out of the cells and little reside in the cells. However, the regulation of the two mutants on the function of CDNF remains unclear. In this study, we investigated the effects of M1 and M7 on the protective activity of CDNF in PC12 cells, which were treated with 6-hydroxydopamine (6-OHDA) to mimic Parkinson's disease. We found that both M1 and M7 could promote survival and inhibit apoptosis more effectively than Wt in 6-OHDA-lesioned PC12 cells. Therefore, these findings will advance our understanding of the important regulation of subdomains on the function of NTFs.

Current Treatments and New, Tentative Therapies for Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative pathology, the origin of which is associated with the death of neuronal cells involved in the production of dopamine. The prevalence of PD has increased exponentially. The aim of this review was to describe the novel treatments for PD that are currently under investigation and study and the possible therapeutic targets. The pathophysiology of this disease is based on the formation of alpha-synuclein folds that generate Lewy bodies, which are cytotoxic and reduce dopamine levels. Most pharmacological treatments for PD target alpha-synuclein to reduce the symptoms. These include treatments aimed at reducing the accumulation of alpha-synuclein (epigallocatechin), reducing its clearance via immunotherapy, inhibiting LRRK2, and upregulating cerebrosidase (ambroxol). Parkinson’s disease continues to be a pathology of unknown origin that generates a significant social cost for the patients who suffer from it. Although there is still no definitive cure for this disease at present, there are numerous treatments available aimed at reducing the symptomatology of PD in addition to other therapeutic alternatives that are still under investigation. However, the therapeutic approach to this pathology should include a combination of pharmacological and non-pharmacological strategies to maximise outcomes and improve symptomatological control in these patients. It is therefore necessary to delve deeper into the pathophysiology of the disease in order to improve these treatments and therefore the quality of life of the patients.

Identification of candidate biomarkers and pathways associated with type 1 diabetes mellitus using bioinformatics analysis

Type 1 diabetes mellitus (T1DM) is a metabolic disorder for which the underlying molecular mechanisms remain largely unclear. This investigation aimed to elucidate essential candidate genes and pathways in T1DM by integrated bioinformatics analysis. In this study, differentially expressed genes (DEGs) were analyzed using DESeq2 of R package from GSE162689 of the Gene Expression Omnibus (GEO). Gene ontology (GO) enrichment analysis, REACTOME pathway enrichment analysis, and construction and analysis of protein–protein interaction (PPI) network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network, and validation of hub genes were performed. A total of 952 DEGs (477 up regulated and 475 down regulated genes) were identified in T1DM. GO and REACTOME enrichment result results showed that DEGs mainly enriched in multicellular organism development, detection of stimulus, diseases of signal transduction by growth factor receptors and second messengers, and olfactory signaling pathway. The top hub genes such as MYC, EGFR, LNX1, YBX1, HSP90AA1, ESR1, FN1, TK1, ANLN and SMAD9 were screened out as the critical genes among the DEGs from the PPI network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network. Receiver operating characteristic curve (ROC) analysis confirmed that these genes were significantly associated with T1DM. In conclusion, the identified DEGs, particularly the hub genes, strengthen the understanding of the advancement and progression of T1DM, and certain genes might be used as candidate target molecules to diagnose, monitor and treat T1DM.

Cerebral Dopamine Neurotrophic Factor (CDNF): Structure, Functions, and Therapeutic Potential

The cerebral dopamine neurotrophic factor (CDNF) together with the mesencephalic astrocyte-derived neurotrophic factor (MANF) form a unique family of neurotrophic factors (NTFs) structurally and functionally different from other proteins with neurotrophic activity. CDNF has no receptors on the cell membrane, is localized mainly in the cavity of endoplasmic reticulum (ER), and its primary function is to regulate ER stress. In addition, CDNF is able to suppress inflammation and apoptosis. Due to its functions, CDNF has demonstrated outstanding protective and restorative properties in various models of neuropathology associated with ER stress, including Parkinson's disease (PD). That is why CDNF already passed clinical trials in patients with PD. However, despite the name, CDNF functions extend far beyond the dopamine system in the brain. In particular, there are data on participation of CDNF in the maturation and maintenance of other neurotransmitter systems, regulation of the processes of neuroplasticity and non-motor behavior. In the present review, we discuss the features of CDNF structure and functions, its protective and regenerative properties.

Glial expression of DmMANF is required for the regulation of activity, sleep and circadian rhythms in the visual system of Drosophila melanogaster

DmMANF, Drosophila melanogaster mesencephalic astrocyte-derived neurotrophic factor (DmMANF) is an evolutionarily conserved orthologue of mammalian MANF. This neurotrophic factor exerts many functions in the Drosophila brain, particularly those dependent on glial cells. As we found in our earlier study, downregulation of DmMANF in glia induces degeneration of glial cells in the first optic neuropil (lamina) where DmMANF abundance is especially high. In the present study, we observed that changes in the level of DmMANF in two types of glia, astrocyte-like glia (AlGl) and ensheathing glia (EnGl), affect activity and sleep of flies. Interestingly, a proper level of DmMANF in AlGl seems to be important in guiding processes of pigment dispersing factor (PDF)-expressing clock neurons. This is supported by our finding that DmMANF overexpression in AlGl leads to structural changes in the architecture of the PDF-positive arborization in the brain. Finally, we detected that DmMANF also affects rhythms in glia themselves, as circadian oscillations in expression of the catalytic α subunit of the sodium pump in the lamina epithelial glia were abolished after DmMANF silencing. DmMANF expressed in AlGl and EnGl seems to affect the activity of neurons leading to changes in behaviour.

Cerebral dopamine neurotrophic factor promotes the proliferation and differentiation of neural stem cells in hypoxic environments

Previous research found that cerebral dopamine neurotrophic factor (CDNF) has a protective effect on brain dopaminergic neurons, and CDNF is regarded as a promising therapeutic agent for neurodegenerative diseases. However, the effects of CDNF on the proliferation, differentiation, and apoptosis of neural stem cells (NSCs), which are very sensitive to hypoxic environments, remain unknown. In this study, NSCs were extracted from the hippocampi of fetal rats and cultured with different concentrations of CDNF. The results showed that 200 nM CDNF was the optimal concentration for significantly increasing the viability of NSCs under non-hypoxic environmental conditions. Then, the cells were cultured with 200 nM CDNF under the hypoxic conditions of 90% N2, 5% CO2, and 5% air for 6 hours. The results showed that CDNF significantly improved the viability of hypoxic NSCs and reduced apoptosis among hypoxic NSCs. The detection of markers showed that CDNF increased the differentiation of hypoxic NSCs into neurons and astrocytes. CDNF also reduced the expression level of Lin28 protein and increased the expression of Let-7 mRNA in NSCs, under hypoxic conditions. In conclusion, we determined that CDNF was able to reverse the adverse proliferation, differentiation, and apoptosis effects that normally affect NSCs in a hypoxic environment. Furthermore, the Lin28/Let-7 pathway may be involved in this regulated function of CDNF. The present study was approved by the Laboratory Animal Centre of Southeast University, China (approval No. 20180924006) on September 24, 2018.

Therapeutic innovation in Parkinson's disease: a 2020 update on disease-modifying approaches

INTRODUCTION

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting more than 10 million patients worldwide. Despite increasing improvements in disease management, a huge medical need still exists as its relentless progression cannot be delayed by current treatments. Therefore, scientists, clinicians, and pharmaceutical companies are hunting new drugs with 'disease-modifying' properties.

AREAS COVERED

This review concentrates on new therapeutics - excluding cell and gene therapies - under investigation for PD with 'disease-modifying' potential. This is a global, comprehensive picture of the current innovative drug pipeline, where the main preclinical and clinical data available are provided. Drug candidates presented include α-synuclein modulating agents, neuroprotective agents and neuroinflammation modulators, kinase modulators, neurotrophic factors, and drugs acting on emerging targets.

EXPERT OPINION

There is excitement for agents with 'disease-modifying' properties and the authors found more than 130 assets, not including cell and gene therapies under investigation - most of them still in preclinical development - meaning that the science is progressing multiple, diverse new opportunities. Many limitations hamper the successful development of these drug candidates such as the translational accuracy of preclinical models, the current clinical development paradigm as well as the lack of biomarkers to be used in diagnosis and therapy management.

Conditioned Medium of Human Menstrual Blood-Derived Endometrial Stem Cells Protects Against MPP+-Induced Cytotoxicity in vitro

Mesenchymal stem cells (MSCs) showed the potential to treat Parkinson’s disease (PD). However, it is unknown whether the conditioned medium of human menstrual blood-derived endometrial stem cells (MenSCs-CM) has the function to alleviate syndromes of PD. In this study, human neuroblastoma SH-SY5Y cells were exposed to neurotoxicant 1-methyl-4-phenylpyridinium (MPP⁺) for inducing a range of response characteristics of PD. After culturing this cell model with 24 h/48 h collected MenSCs-CM for different days, cell viability, pro-inflammation cytokines, mitochondrial membrane potential (ΔΨm), oxidative stress, and cell apoptosis were detected. Finally, protein assay was performed to detect 12 kinds of neurotrophic factors inside MenSCs-CM. Our results showed that MPP⁺ caused SH-SY5Y cell viability reduction as an increasing dose and time dependent manner. MPP⁺ treatment resulted in inflammation, mitochondrial dysfunction, reactive oxygen species (ROS) production accumulation, and apoptosis of SH-SY5Y at its IC50 concentration. Forty-eight hours-collected MenSCs-CM and culturing with the MPP⁺-treated SH-SY5Y for 2 days are the optimized condition to increase cell viability. Besides, MenSCs-CM was efficacious against MPP⁺ induced inflammation, ΔΨm loss, ROS generation, and it could significantly decrease cells numbers in late apoptosis stage. What’s more, protein assay showed that MenSCs-CM contained various neuroprotective factors. Our study provided the first evidence that MenSCs-CM has a protective effect on MPP⁺-induced cytotoxicity in various aspects, and firstly showed that MenSCs can release at least 12 kinds of neurotrophic factors to medium, which may contribute to the protective function of MenSCs-CM to treat PD. This research enlightening that MenSCs-CM is beneficial in the therapy for PD and probably also for other neurodegenerative diseases.

Effect of cerebral dopamine neurotrophic factor on endogenous neural progenitor cell migration in a rat model of Parkinson's disease

This study investigated the ability of intra-subventricular zone (SVZ) administration of cerebral dopamine neurotrophic factor (CDNF) on neural progenitor cells (NPCs) attraction from the SVZ toward the 6-hydroxydopamine (6-OHDA)-lesioned striatum and improvement of motor dysfunctions in Parkinsonian rats. Male Wistar rats were assigned to four groups of the sham model (Sham), 6-OHDA-lesioned (OH), 6-OHDA-lesioned plus CDNF vehicle (OH+Vehicle), and 6-OHDA-lesioned plus CDNF (OH+CDNF). The animal model of Parkinson's disease (PD) was induced by unilateral intra-striatal infusion of 6-OHDA. Rats in the treatment groups received an intra-SVZ injection of CDNF or the vehicle of CDNF two weeks after PD model induction and were then subjected to the beam and bar tests on days 7, 14, and 21 after CDNF injection. Bromodeoxyuridine (BrdU) was intraperitoneally injected to label newly generated cells. Migration and proliferation of NPCs were assessed by BrdU/doublecortin (DCX) double immunofluorescence method on days 7, 14, and 21 after CDNF infusion. 6-OHDA in the OH group induced catalepsy and increased elapsed time in the beam test compared to the Sham group. However, administration of CDNF improved the motor performance and increased the number of DCX expressing neuroblasts in the SVZ as compared to the OH and OH+Vehicle groups. CDNF also enhanced cell proliferation and increased the number of migrated BrdU- and DCX-positive cells toward the lesioned striatum in the OH+CDNF group. These results suggest that CDNF enhances the proliferation and migration of neural stem cells (NSCs) toward the lesioned striatum accompanied by improvement of PD-induced motor dysfunctions.

Association between cerebral dopamine neurotrophic factor (CDNF) 2 polymorphisms and schizophrenia susceptibility and symptoms in the Han Chinese population

Background

Schizophrenia (SZ) is a complex polygenic psychiatric disorder caused in part by abnormal dopamine levels. Cerebral dopamine neurotrophic factor (CDNF) 2 is known to protect and repair the dopaminergic system. Dopamine dysfunction is one of the pathogenesis of SZ. However, the relationship between CDNF2 and SZ has not been previously investigated. We speculated that CDNF2 may be a susceptibility factor for SZ.

Methods

To address this issue, we carried out a study to investigate the association between CDNF2 and SZ in the total sample 1371 (670 SZ patients and 701 healthy controls) Han Chinese population. Stage 1 included 528 SZ patients and 528 healthy controls; and stage 2 included 142 SZ patients and 173 healthy controls. The allele and genotype frequencies of five single nucleotide polymorphisms (rs2577074, rs2577075, rs2249810, rs6506891, and rs2118343) of CDNF2 were compared between patients and controls.

Results

We found a significant association in allele and genotype frequencies between the two groups at rs2249810 (χ² = 4.38 and 6.45, respectively; P = 0.03 and 0.04, respectively). An association was also observed in males at rs2249810 (χ² = 8.76; P = 0.03). Haplotype TGATC differed between SZ and controls in stage 2 samples (χ² = 6.38; P = 0.01), and rs2118343 genotypes were associated with negative factor scores (F = 4.396; P = 0.01).

Conclusions

These results suggest that rs2249810 and haplotype TGATC of CDNF2 are an SZ susceptibility locus and factor, respectively, and that rs2118343 genotypes are associated with negative symptoms of SZ in the Han Chinese population.

Downregulation of DmMANF in Glial Cells Results in Neurodegeneration and Affects Sleep and Lifespan in Drosophila melanogaster

In Drosophila melanogaster, mesencephalic astrocyte-derived neurotrophic factor (DmMANF) is an evolutionarily conserved ortholog of mammalian MANF and cerebral dopamine neurotrophic factor (CDNF), which have been shown to promote the survival of dopaminergic neurons in the brain. We observed especially high levels of DmMANF in the visual system of Drosophila, particularly in the first optic neuropil (lamina). In the lamina, DmMANF was found in glial cells (surface and epithelial glia), photoreceptors and interneurons. Interestingly, silencing of DmMANF in all neurons or specifically in photoreceptors or L2 interneurons had no impact on the structure of the visual system. However, downregulation of DmMANF in glial cells induced degeneration of the lamina. Remarkably, this degeneration in the form of holes and/or tightly packed membranes was observed only in the lamina epithelial glial cells. Those membranes seem to originate from the endoplasmic reticulum, which forms autophagosome membranes. Moreover, capitate projections, the epithelial glia invaginations into photoreceptor terminals that are involved in recycling of the photoreceptor neurotransmitter histamine, were less numerous after DmMANF silencing either in neurons or glial cells. The distribution of the alpha subunit of Na+/K+-ATPase protein in the lamina cell membranes was also changed. At the behavioral level, silencing of DmMANF either in neurons or glial cells affected the daily activity/sleep pattern, and flies showed less activity during the day but higher activity during the night than did controls. In the case of silencing in glia, the lifespan of flies was also shortened. The obtained results showed that DmMANF regulates many functions in the brain, particularly those dependent on glial cells.

Transcription Factors: Potential Cell Death Markers in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease with a long preclinical phase. The continuous loss of dopaminergic (DA) neurons is one of the pathogenic hallmarks of PD. Diagnosis largely depends on clinical observation, but motor dysfunctions do not emerge until 70%-80% of the nigrostriatal nerve terminals have been destroyed. Therefore, a biomarker that indicates the degeneration of DA neurons is urgently needed. Transcription factors are sequence-specific DNA-binding proteins that regulate RNA synthesis from a DNA template. The precise control of gene expression plays a critical role in the development, maintenance, and survival of cells, including DA neurons. Deficiency of certain transcription factors has been associated with DA neuron loss and PD. In this review, we focus on some transcription factors and discuss their structure, function, mechanisms of neuroprotection, and their potential for use as biomarkers indicating the degeneration of DA neurons.