MicroRNA-326 Inhibits Apoptosis and Promotes Proliferation of Dopaminergic Neurons in Parkinson's Disease Through Suppression of KLK7-Mediated MAPK Signaling Pathway

Emerging role of Nrf2 in Parkinson's disease therapy: a critical reassessment

Parkinson's disease (PD) is the neurodegenerative disorder characterized by the progressive degeneration of nigrostriatal dopaminergic neurons, leading to the range of motor and non-motor symptoms. There is mounting evidence suggesting that oxidative stress, neuroinflammation and mitochondrial dysfunction play pivotal roles in the pathogenesis of PD. Current therapies only alleviate perturbed motor symptoms. Therefore, it is essential to find out new therapies that allow us to improve not only motor symptoms, but non-motor symptoms like cognitive impairment and modulate disease progression. Nuclear factor erythroid 2-related factor 2 (Nrf2) is transcription factor that regulates the expression of numerous anti-oxidants and cytoprotective genes can counteract oxidative stress, neuroinflammation and mitochondrial dysfunction, thereby potentially ameliorating PD-associated pathology. The current review discusses about the Nrf2 structure and function with special emphasis on various molecular signalling pathways involved in positive and negative modulation of Nrf2, namely Glycogen synthase kinase-3β, Phosphoinositide-3-kinase, AMP-activated protein kinase, Mitogen activated protein kinase, nuclear factor-κB and P62. Furthermore, this review highlights the various Nrf2 activators as promising therapeutic agents for slowing down the progression of PD.

Non-coding RNAs as therapeutic targets in Parkinson's Disease: A focus on dopamine

Parkinson's Disease is a highly complicated neurological disorder, with a key manifestation of loss of dopaminergic neurons. Despite the plethora of medicines that alleviate the symptoms, there is an urgent need for new treatments acting on the fundamental pathology of PD. Non-coding RNAs are becoming increasingly important in gene regulation and various cellular processes and are found to play a role in PD pathophysiology. This review analyzes the cross-talk of distinct ncRNAs with dopamine signaling. We attempt to constrain the various ncRNA networks that can activate dopamine production. First, we describe the deregulation of miRNAs that target dopamine receptors and have been implicated in PD. Next, we turn to the functions of lncRNAs in dopaminergic neurons and the connections to susceptibility genes for PD. Finally, we will analyze the novel circRNAs, such as ciRS-7, which may modulate dopamine-linked processes and serve as possible PD biomarkers. In this review, we describe recent progress in dopamine neuron revival to treat PD and the therapeutic potential of ncRNA. This review critically evaluates the available data, and we predict the role of some ncRNAs, such as PTBP1, to become candidate treatment targets in the future. Thus, this review aims to summarize the molecular causes for the deficit in dopamine signaling in PD and point to novel ncRNAs-linked therapeutic directions in neuroscience.

Parkinson's Disease and MicroRNAs: A Duel Between Inhibition and Stimulation of Apoptosis in Neuronal Cells

Parkinson's disease (PD) is one of the most prevalent diseases of central nervous system that is caused by degeneration of the substantia nigra's dopamine-producing neurons through apoptosis. Apoptosis is regulated by initiators' and executioners' caspases both in intrinsic and extrinsic pathways, further resulting in neuronal damage. In that context, targeting apoptosis appears as a promising therapeutic approach for treating neurodegenerative diseases. Non-coding RNAs-more especially, microRNAs, or miRNAs-are a promising target for the therapy of neurodegenerative diseases because they are essential for a number of cellular processes, including signaling, apoptosis, cell proliferation, and gene regulation. It is estimated that a substantial portion of coding genes (more than 60%) are regulated by miRNAs. These small regulatory molecules can have wide-reaching consequences on cellular processes like apoptosis, both in terms of intrinsic and extrinsic pathways. Furthermore, it was recommended that a disruption in miRNA expression levels could also result in perturbation of typical apoptosis pathways, which may be a factor in certain diseases like PD. The latest research on miRNAs and their impact on neural cell injury in PD models by regulating the apoptosis pathway is summarized in this review article. Furthermore, the importance of lncRNA/circRNA-miRNA-mRNA network for regulating apoptosis pathways in PD models and treatment is explored. These results can be utilized for developing new strategies in PD treatment.

Non-Coding RNAs and Neurodegenerative Diseases: Information of their Roles in Apoptosis

Apoptosis can be known as a key factor in the pathogenesis of neurodegenerative disorders. In disease conditions, the rate of apoptosis expands and tissue damage may become apparent. Recently, the scientific studies of the non-coding RNAs (ncRNAs) has provided new information of the molecular mechanisms that contribute to neurodegenerative disorders. Numerous reports have documented that ncRNAs have important contributions to several biological processes associated with the increase of neurodegenerative disorders. In addition, microRNAs (miRNAs), circular RNAs (circRNAs), as well as, long ncRNAs (lncRNAs) represent ncRNAs subtypes with the usual dysregulation in neurodegenerative disorders. Dysregulating ncRNAs has been associated with inhibiting or stimulating apoptosis in neurodegenerative disorders. Therefore, this review highlighted several ncRNAs linked to apoptosis in neurodegenerative disorders. CircRNAs, lncRNAs, and miRNAs were also illustrated completely regarding the respective signaling pathways of apoptosis.

The mechanistic view of non-coding RNAs as a regulator of inflammatory pathogenesis of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor and non-motor symptoms. Emerging evidence suggests that inflammation plays a crucial role in the pathogenesis of PD, with the NLRP3 inflammasome implicated as a key mediator. Nfon-coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), have recently garnered attention for their regulatory roles in various biological processes, including inflammation. This review aims to provide a mechanistic insight into how ncRNAs function as regulators of inflammatory pathways in PD, with a specific focus on the NLRP3 inflammasome. We discuss the dysregulation of miRNAs and lncRNAs in PD pathogenesis and their impact on neuroinflammation through modulation of NLRP3 activation, cytokine production, and microglial activation. Additionally, we explore the crosstalk between ncRNAs, alpha-synuclein pathology, and mitochondrial dysfunction, further elucidating the intricate network underlying PD-associated inflammation. Understanding the mechanistic roles of ncRNAs in regulating inflammatory pathways may offer novel therapeutic targets for the treatment of PD and provide insights into the broader implications of ncRNA-mediated regulation in neuroinflammatory diseases.

CircHIVEP2 alleviates Parkinson's nerve damage and inflammatory response by targeting miR-485-3p

OBJECTIVE

Dysregulation of covalently closed circular RNAs (circRNAs) has been associated with neurological disorders, the role of circHIVP2 in Parkinson's disease (PD) and its molecular mechanism is not well understood.

METHODS

127 patients with PD and 85 healthy people were enrolled. RT-qPCR was employed to examine the levels of circHIVEP2. ROC curve to explore the diagnostic. Mpp+ induced the SH-SY5Y to construct an in vitro PD cell model. Cell viability, apoptosis, and secretion levels of inflammatory factors were analyzed by CCK-8, flow cytometry, and ELISA assay. CircHIVEP2 targets miRNA predicted by bioinformatics database and validated by the dual luciferase reporter and RIP assays.

RESULTS

CircHIVEP2 was typically lower in PD patients than in controls. CircHIVEP2 has certain specificity and sensitivity to recognize PD patients from healthy individuals. miR-485-3p, a target miRNA of circHIVEP2, was significantly elevated in PD patients. Additionally, MPP+ induction reduced cell viability and promoted apoptosis and inflammatory factor overproduction. However, overexpression of circHIVEP2 significantly inhibited the effects of MPP+, but this inhibition was significantly attenuated by elevated miR-485-3p.

CONCLUSION

circHIVEP2 is a potential diagnostic biomarker for PD, and its upregulation mitigated MPP+-induced nerve damage and inflammation and this may be through targeted by the miR-485-3p.

ncRNAs: an unexplored cellular defense mechanism in leprosy

Leprosy is an infectious disease primarily caused by the obligate intracellular parasite Mycobacterium leprae. Although it has been considered eradicated in many countries, leprosy continues to be a health issue in developing nations. Besides the social stigma associated with it, individuals affected by leprosy may experience nerve damage leading to physical disabilities if the disease is not properly treated or early diagnosed. Leprosy is recognized as a complex disease wherein socioenvironmental factors, immune response, and host genetics interact to contribute to its development. Recently, a new field of study called epigenetics has emerged, revealing that the immune response and other mechanisms related to infectious diseases can be influenced by noncoding RNAs. This review aims to summarize the significant advancements concerning non-coding RNAs in leprosy, discussing the key perspectives on this novel approach to comprehending the pathophysiology of the disease and identifying molecular markers. In our view, investigations on non-coding RNAs in leprosy hold promise and warrant increased attention from researches in this field.

Mechanism and Therapeutic Prospect of miRNAs in Neurodegenerative Diseases

MicroRNAs (miRNAs) are the smallest class of noncoding RNAs, which widely exist in animals and plants. They can inhibit translation or overexpression by combining with mRNA and participate in posttranscriptional regulation of genes, resulting in reduced expression of target proteins, affecting the development, growth, aging, metabolism, and other physiological and pathological processes of animals and plants. It is a powerful negative regulator of gene expression. It mediates the information exchange between different cellular pathways in cellular homeostasis and stress response and regulates the differentiation, plasticity, and neurotransmission of neurons. In neurodegenerative diseases, in addition to the complex interactions between genetic susceptibility and environmental factors, miRNAs can serve as a promising diagnostic tool for diseases. They can also increase or reduce neuronal damage by regulating the body's signaling pathways, immune system, stem cells, gut microbiota, etc. They can not only affect the occurrence of diseases and exacerbate disease progression but also promote neuronal repair and reduce apoptosis, to prevent and slow down the development of diseases. This article reviews the research progress of miRNAs on the mechanism and treatment of neurodegenerative diseases in the nervous system. This trial is registered with NCT01819545, NCT02129452, NCT04120493, NCT04840823, NCT02253732, NCT02045056, NCT03388242, NCT01992029, NCT04961450, NCT03088839, NCT04137926, NCT02283073, NCT04509271, NCT02859428, and NCT05243017.

Combined surface functionalization of MSC membrane and PDA inhibits neurotoxicity induced by Fe3O4 in mice based on apoptosis and autophagy through the ASK1/JNK signaling pathway

The extensive utilization of iron oxide nanoparticles in medical and life science domains has led to a substantial rise in both occupational and public exposure to these particles. The potential toxicity of nanoparticles to living organisms, their impact on the environment, and the associated risks to human health have garnered significant attention and come to be a prominent area in contemporary research. The comprehension of the potential toxicity of nanoparticles has emerged as a crucial concern to safeguard human health and facilitate the secure advancement of nanotechnology. As nanocarriers and targeting agents, the biocompatibility of them determines the use scope and application prospects, meanwhile surface modification becomes an important measure to improve the biocompatibility. Three different types of iron oxide nanoparticles (Fe3O4, Fe3O4@PDA and MSCM-Fe3O4@PDA) were injected into mice through the tail veins. The acute neurotoxicity of them in mice was evaluated by measuring the levels of autophagy and apoptosis in the brain tissues. Our data revealed that iron oxide nanoparticles could cause nervous system damage by regulating the ASK1/JNK signaling pathway. Apoptosis and autophagy may play potential roles in this process. Exposure to combined surface functionalization of mesenchymal stem cell membrane and polydopamine showed the neuroprotective effect and may alleviate brain nervous system disorders.

The Neuroepigenetic Landscape of Vertebrate and Invertebrate Models of Neurodegenerative Diseases

Vertebrate and invertebrate models of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, have been paramount to our understanding of the pathophysiology of these conditions; however, the brain epigenetic landscape is less well established in these disease models. DNA methylation, histone modifications, and microRNAs are among commonly studied mechanisms of epigenetic regulation. Genome-wide studies and candidate studies of specific methylation marks, histone marks, and microRNAs have demonstrated the dysregulation of these mechanisms in models of neurodegenerative diseases; however, the studies to date are scarce and inconclusive and the implications of many of these changes are still not fully understood. In this review, we summarize epigenetic changes reported to date in the brain of vertebrate and invertebrate models used to study neurodegenerative diseases, specifically diseases affecting the aging population. We also discuss caveats of epigenetic research so far and the use of disease models to understand neurodegenerative diseases, with the aim of improving the use of model organisms in this context in future studies.

The Role of Non-Coding RNAs in the Pathogenesis of Parkinson’s Disease: Recent Advancement

Parkinson’s disease (PD) is a prevalent neurodegenerative aging disorder that manifests as motor and non-motor symptoms, and its etiopathogenesis is influenced by non-coding RNAs (ncRNAs). Signal pathway and gene sequence studies have proposed that alteration of ncRNAs is relevant to the occurrence and development of PD. Furthermore, many studies on brain tissues and body fluids from patients with PD indicate that variations in ncRNAs and their target genes could trigger or exacerbate neurodegenerative pathogenesis and serve as potential non-invasive biomarkers of PD. Numerous ncRNAs have been considered regulators of apoptosis, α-syn misfolding and aggregation, mitochondrial dysfunction, autophagy, and neuroinflammation in PD etiology, and evidence is mounting for the determination of the role of competing endogenous RNA (ceRNA) mechanisms in disease development. In this review, we discuss the current knowledge regarding the regulation and function of ncRNAs as well as ceRNA networks in PD pathogenesis, focusing on microRNAs, long ncRNAs, and circular RNAs to increase the understanding of the disease and propose potential target identification and treatment in the early stages of PD.

lncRNA NEAT1 promotes autophagy of neurons in mice by impairing miR-107-5p

This work focused on the exploration of NEAT1 in Parkinson’s disease (PD) and aimed to explore its effects on PD and related molecular mechanisms. Two experimental models were initially constructed, including MPTP-induced mice in vivo and the MPP+-induced SH-SY5Y cell line in vitro. Immunofluorescence assays were conducted to determine the TH+ positive cell rate. Pole tests and rotarod tests were also performed for the visualization of behavioral changes in mice. Cellular apoptosis was determined using MTT and flow cytometry assays. Changes in the number of autophagosomes were obtained under a transmission electron microscope. The content of dopamine was confirmed by high performance liquid chromatography. The targeted interrelationship between miR-107-5p and NEAT1 was clarified via dual-luciferase reporter gene assays. Meanwhile, mRNA and protein expressions were also detected using qRT-PCR and Western blot respectively. Furthermore, the level of NEAT1 was positively correlated with MPP+ concentration. Interfering with NEAT1 in the present study promoted cellular proliferation and mediated SH-SY5Y cell apoptosis and autophagy treated with MPP+. An increase was discovered in TH positive neurons and suppressive autophagy in PD mice. miR-107-5p was then considered as a NEAT1 putative target involving apoptosis and autophagy of SH-SY5Y cells. Interfering with NEAT1 efficiently facilitated the viability of SH-SY5Y cells and drastically suppressed autophagy and apoptosis of PD mice induced by MPTP- via elevating miR-107-5p level, which indicated that lncRNA NEAT1 acted as a latent therapeutic factor for PD treatment.

MicroRNA Alteration, Application as Biomarkers, and Therapeutic Approaches in Neurodegenerative Diseases

MicroRNAs (miRNAs) are essential post-transcriptional gene regulators involved in various neuronal and non-neuronal cell functions and play a key role in pathological conditions. Numerous studies have demonstrated that miRNAs are dysregulated in major neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, or Huntington’s disease. Hence, in the present work, we constructed a comprehensive overview of individual microRNA alterations in various models of the above neurodegenerative diseases. We also provided evidence of miRNAs as promising biomarkers for prognostic and diagnostic approaches. In addition, we summarized data from the literature about miRNA-based therapeutic applications via inhibiting or promoting miRNA expression. We finally identified the overlapping miRNA signature across the diseases, including miR-128, miR-140-5p, miR-206, miR-326, and miR-155, associated with multiple etiological cellular mechanisms. However, it remains to be established whether and to what extent miRNA-based therapies could be safely exploited in the future as effective symptomatic or disease-modifying approaches in the different human neurodegenerative disorders.

Effects of miRNAs in exosomes derived from α-synuclein overexpressing SH-SY5Y cells on autophagy and inflammation of microglia

Our previous study has revealed that GFP-α-synuclein overexpressing SH-SY5Y cells-derived exosomes (GFP-SNCA Exo) decrease autophagy in microglia via their load of miRNAs. However, it is unclear whether GFP-SNCA Exo can affect microglial inflammation via modulation of autophagy. In order to investigate the effects of miRNAs carried by GFP-SNCA Exo on autophagy and inflammation of microglia. SH-SY5Y cells were transfected with lentivirus expressing α-synuclein and then their exosomes were collected. Western blot and laser confocal images showed that α-synuclein transferred between SH-SY5Y cells and microglia through exosomes. Differentially expressed miRNAs between GFP-SNCA Exo and the vector exosomes were detected by microarray analysis. After bioinformatics analysis of the differentially expressed miRNAs, we found that their target genes were enriched in the MAPK and autophagy-associated signaling pathway. The expression of P62, p-JNK/JNK, and p-ERK/ERK and the release of IL-6 significantly increased whereas LC3 II/I decreased in microglia exposed to GFP-SNCA Exo for 48 h when compared to the control group. But rapamycin could reverse the increasing expression of p-JNK/JNK, p-ERK/ERK and the release of IL-6 induced by GFP-SNCA Exo. Dual immunofluorescence staining for LC3B and LAMP1 showed that the fluorescence density of LC3B decreased and the fluorescence of LC3B and LAMP1 were not co-located in microglia after 48 h co-culture with GFP-SNCA Exo compared with the control group, which indicated that these exosomes decreased autophagy and impaired the autophagy flux in recipient microglia. Taken together, our results indicate that GFP-SNCA Exo activate the MAPK signaling pathway and inflammation by decreasing autophagy in microglia.

Hypoxic preconditioning rejuvenates mesenchymal stem cells and enhances neuroprotection following intracerebral hemorrhage via the miR-326-mediated autophagy

BACKGROUND

Intracerebral hemorrhage (ICH) is a major public health concern, and mesenchymal stem cells (MSCs) hold great potential for treating ICH. However, the quantity and quality of MSCs decline in the cerebral niche, limiting the potential efficacy of MSCs. Hypoxic preconditioning is suggested to enhance the survival of MSCs and augment the therapeutic efficacy of MSCs in ICH. MicroRNAs (miRNAs) are known to mediate cellular senescence. However, the precise mechanism by which miRNAs regulate the senescence of hypoxic MSCs remains to be further studied. In the present study, we evaluated whether hypoxic preconditioning enhances the survival and therapeutic effects of olfactory mucosa MSC (OM-MSC) survival and therapeutic effects in ICH and investigated the mechanisms by which miRNA ameliorates hypoxic OM-MSC senescence.

METHODS

In the in vivo model, ICH was induced in mice by administration of collagenase IV. At 24 h post-ICH, 5 × 10⁵ normoxia or hypoxia OM-MSCs or saline was administered intracerebrally. The behavioral outcome, neuronal apoptosis, and OM-MSC survival were evaluated. In the in vitro model, OM-MSCs were exposed to hemin. Cellular senescence was examined by evaluating the expressions of P16INK4A, P21, P53, and by β-galactosidase staining. Microarray and bioinformatic analyses were performed to investigate the differences in the miRNA expression profiles between the normoxia and hypoxia OM-MSCs. Autophagy was confirmed using the protein expression levels of LC3, P62, and Beclin-1.

RESULTS

In the in vivo model, transplanted OM-MSCs with hypoxic preconditioning exhibited increased survival and tissue-protective capability. In the in vitro model, hypoxia preconditioning decreased the senescence of OM-MSCs exposed to hemin. Bioinformatic analysis identified that microRNA-326 (miR-326) expression was significantly increased in the hypoxia OM-MSCs compared with that of normoxia OM-MSCs. Upregulation of miR-326 alleviated normoxia OM-MSC senescence, whereas miR-326 downregulation increased hypoxia OM-MSC senescence. Furthermore, we showed that miR-326 alleviated cellular senescence by upregulating autophagy. Mechanistically, miR-326 promoted the autophagy of OM-MSCs via the PI3K signaling pathway by targeting polypyrimidine tract-binding protein 1 (PTBP1).

CONCLUSIONS

Our study shows that hypoxic preconditioning delays OM-MSC senescence and augments the therapeutic efficacy of OM-MSCs in ICH by upregulating the miR-326/PTBP1/PI3K-mediated autophagy.

lncRNA NEAT1 prompts autophagy and apoptosis in MPTP-induced Parkinson's disease by impairing miR-374c-5p

Long non-coding RNAs (lncRNAs) play biological roles in brain disorder and neurodegenerative diseases. As the functions of lncRNA NEAT1 in Parkinson's disease (PD) remain unknown, in the present study, we aimed to explore the roles and underlying molecular mechanisms of NEAT1 in PD. A PD mouse model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and a cell model of SH-SY5Y induced by N-methyl-4-phenylpyridinium (MPP+) were established. The ratio of tyrosine hydroxylase (TH+) cells was determined by immunofluorescence assay, and the behavioral changes in mice were observed using pole tests and rotarod tests. The cellular viability and apoptosis of SH-SY5Y were detected by MTT assay and flow cytometric analysis, respectively, and the number of autophagosomes was subsequently measured by transmission electron microscopy. High-performance liquid chromatography was performed to detect the content of dopamine, and a dual-luciferase reporter assay was used to clarify the target of NEAT1 simultaneously. The results demonstrated that the level of NEAT1 was upregulated in the MPTP-induced PD mice, dopamine neurons, and the SH-SY5Y cells treated with MPP+, whereas the level of miR-374c-5p was downregulated. NEAT1 level was positively correlated with MPP+ in a concentration-dependent manner. NEAT1 inhibition efficiently facilitated cell proliferation but inhibited apoptosis and autophagy in the MPP+-treated SH-SY5Y cells. Additionally, silencing of NEAT1 increased the TH+ rate of neurons and suppressed autophagy greatly in PD mice. As a possible target of NEAT1, miR-374c-5p could impact on the apoptosis and autophagy of the SH-SY5Y cells. NEAT1 inhibition upregulated the expression of miR-374c-5p, enhanced SH-SY5Y cell viability, and repressed autophagy and apoptosis in MPTP-induced PD mice. These findings indicated a potential therapeutic role of NEAT1 in treating PD.

Chemical and Biological Molecules Involved in Differentiation, Maturation, and Survival of Dopaminergic Neurons in Health and Parkinson's Disease: Physiological Aspects and Clinical Implications

Parkinson’s disease (PD) is one of the most common neurodegenerative disease characterized by a specific and progressive loss of dopaminergic (DA) neurons and dopamine, causing motor dysfunctions and impaired movements. Unfortunately, available therapies can partially treat the motor symptoms, but they have no effect on non-motor features. In addition, the therapeutic effect reduces gradually, and the prolonged use of drugs leads to a significative increase in the number of adverse events. For these reasons, an alternative approach that allows the replacement or the improved survival of DA neurons is very appealing for the treatment of PD patients and recently the first human clinical trials for DA neurons replacement have been set up. Here, we review the role of chemical and biological molecules that are involved in the development, survival and differentiation of DA neurons. In particular, we review the chemical small molecules used to differentiate different type of stem cells into DA neurons with high efficiency; the role of microRNAs and long non-coding RNAs both in DA neurons development/survival as far as in the pathogenesis of PD; and, finally, we dissect the potential role of exosomes carrying biological molecules as treatment of PD.

MicroRNA Dysregulation in Parkinson's Disease: A Narrative Review

Parkinson’s disease (PD) is a severely debilitating neurodegenerative disease, affecting the motor system, leading to resting tremor, cogwheel rigidity, bradykinesia, walking and gait difficulties, and postural instability. The severe loss of dopaminergic neurons in the substantia nigra pars compacta causes striatal dopamine deficiency and the presence of Lewy bodies indicates a pathological hallmark of PD. Although the current treatment of PD aims to preserve dopaminergic neurons or to replace dopamine depletion in the brain, it is notable that complete recovery from the disease is yet to be achieved. Given the complexity and multisystem effects of PD, the underlying mechanisms of PD pathogenesis are yet to be elucidated. The advancement of medical technologies has given some insights in understanding the mechanism and potential treatment of PD with a special interest in the role of microRNAs (miRNAs) to unravel the pathophysiology of PD. In PD patients, it was found that striatal brain tissue and dopaminergic neurons from the substantia nigra demonstrated dysregulated miRNAs expression profiles. Hence, dysregulation of miRNAs may contribute to the pathogenesis of PD through modulation of PD-associated gene and protein expression. This review will discuss recent findings on PD-associated miRNAs dysregulation, from the regulation of PD-associated genes, dopaminergic neuron survival, α-synuclein-induced inflammation and circulating miRNAs. The next section of this review also provides an update on the potential uses of miRNAs as diagnostic biomarkers and therapeutic tools for PD.

Restored microRNA-326-5p Inhibits Neuronal Apoptosis and Attenuates Mitochondrial Damage via Suppressing STAT3 in Cerebral Ischemia/Reperfusion Injury

Studies have greatly explored the role of microRNAs (miRNAs) in cerebral ischemia/reperfusion injury (CI/RI). But the specific mechanism of miR-326-5p in CI/RI is still elusive. Hence, this study was to unmask the mechanism of miR-326-5p/signal transducer and activator of transcription-3 (STAT3) axis in CI/RI. Two models (oxygen and glucose deprivation [OGD] in primary rat cortical neurons and middle cerebral artery occlusion [MCAO] in Sprague-Dawley rats) were established to mimic CI/RI in vitro and in vivo, respectively. Loss- and gain-of function assays were performed with OGD-treated neurons and with MCAO rats. Afterward, viability, apoptosis, oxidative stress and mitochondrial membrane potential in OGD-treated neurons were tested, as well as pathological changes, apoptosis and mitochondrial membrane potential in brain tissues of MCAO rats. Mitofusin-2 (Mfn2), miR-326-5p and STAT3 expression in OGD-treated neurons and in brain tissues of MCAO rats were detected. Mfn2 and miR-326-5p were reduced, and STAT3 was elevated in OGD-treated neurons and brain tissues of MCAO rats. miR-326-5p targeted and negatively regulated STAT3 expression. Restoring miR-326-5p or reducing STAT3 reinforced viability, inhibited apoptosis and oxidative stress, increased mitochondrial membrane potential and increased Mfn2 expression in OGD-treated neurons. Up-regulating miR-326-5p or down-regulating STAT3 relieved pathological changes, inhibited apoptosis and elevated mitochondrial membrane potential and Mfn2 expression in brain tissues of rats with MCAO. This study elucidates that up-regulated miR-326-5p or down-regulated STAT3 protects against CI/RI by elevating Mfn2 expression.

The Role of Non-Coding RNAs in the Neuroprotective Effects of Glutathione

The establishment of antioxidative defense systems might have been mandatory for most living beings with aerobic metabolisms, because oxygen consumption produces adverse byproducts known as reactive oxygen species (ROS). The brain is especially vulnerable to the effect of ROS, since the brain has large amounts of unsaturated fatty acids, which are a target of lipid oxidation, as well as comparably high-energy consumption compared to other organs that results in ROS release from mitochondria. Thus, dysregulation of the synthesis and/or metabolism of antioxidants-particularly glutathione (GSH), which is one of the most important antioxidants in the human body-caused oxidative stress states that resulted in critical diseases, including neurodegenerative diseases in the brain. GSH plays crucial roles not only as an antioxidant but also as an enzyme cofactor, cysteine storage form, the major redox buffer, and a neuromodulator in the central nervous system. The levels of GSH are precisely regulated by uptake systems for GSH precursors as well as GSH biosynthesis and metabolism. The rapid advance of RNA sequencing technologies has contributed to the discovery of numerous non-coding RNAs with a wide range of functions. Recent lines of evidence show that several types of non-coding RNAs, including microRNA, long non-coding RNA and circular RNA, are abundantly expressed in the brain, and their activation or inhibition could contribute to neuroprotection through the regulation of GSH synthesis and/or metabolism. Interestingly, these non-coding RNAs play key roles in gene regulation and growing evidence indicates that non-coding RNAs interact with each other and are co-regulated. In this review, we focus on how the non-coding RNAs modulate the level of GSH and modify the oxidative stress states in the brain.

Evolutionary Changes in the Interaction of miRNA With mRNA of Candidate Genes for Parkinson's Disease

Parkinson’s disease (PD) exhibits the second-highest rate of mortality among neurodegenerative diseases. PD is difficult to diagnose and treat due to its polygenic nature. In recent years, numerous studies have established a correlation between this disease and miRNA expression; however, it remains necessary to determine the quantitative characteristics of the interactions between miRNAs and their target genes. In this study, using novel bioinformatics approaches, the quantitative characteristics of the interactions between miRNAs and the mRNAs of candidate PD genes were established. Of the 6,756 miRNAs studied, more than one hundred efficiently bound to mRNA of 61 candidate PD genes. The miRNA binding sites (BS) were located in the 5′-untranslated region (5′UTR), coding sequence (CDS) and 3′-untranslated region (3′UTR) of the mRNAs. In the mRNAs of many genes, the locations of miRNA BS with overlapping nucleotide sequences (clusters) were identified. Such clusters substantially reduced the proportion of nucleotide sequences of miRNA BS in the 5′UTRs, CDSs, and 3′UTRs. The organization of miRNA BS into clusters leads to competition among miRNAs to bind mRNAs. Differences in the binding characteristics of miRNAs to the mRNAs of genes expressed at different rates were identified. Single miRNA BS, polysites for the binding for one miRNA, and multiple BS for two or more miRNAs in one mRNA were identified. Evolutionary changes in the BS of miRNAs and their clusters in 5′UTRs, CDSs and 3′UTRs of mRNA of orthologous candidate PD genes were established. Based on the quantitative characteristics of the interactions between miRNAs and mRNAs candidate PD genes, several associations recommended as markers for the diagnosis of PD.

Assessment of the role of non-coding RNAs in the pathophysiology of Parkinson's disease

Parkinson's disease (PD) is the second main neurodegenerative disease causing motor abnormalities in the middle-aged and old individuals. In some cases, cognitive dysfunction also occurs. The clinical signs of PD are bradykinesia, rigidity and resting tremor. As these signs might be detected in other neurological conditions such as multiple systems atrophy and corticobasal degeneration, it is necessary to find specific and sensitive markers for this disorder. Non-coding RNAs are implicated in the different PD-associated features such as α-synuclein expression and Lewy body construction, mitochondrial dysfunction, apoptosis, neuroinflammation and defects in glial cell-derived neurotrophic factor. Several researches have confirmed dysregulation of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in brain tissues, plasma exosomes and leukocytes of affected individuals or animal models of PD. A number of these transcripts directly regulate the neurodegenerative process in PD. In the current study, we review the current data about dysregulation of ncRNAs and the role of their genomic variants in the pathogenesis of PD.

LncRNA BDNF-AS promotes autophagy and apoptosis in MPTP-induced Parkinson's disease via ablating microRNA-125b-5p

BACKGROUNDS

Recently, extensive evidence has indicated that the biological role of long non-coding RNAs (lncRNAs) in neurodegenerative diseases is becoming increasingly evident. The lncRNA brain-derived neurotrophic factor anti-sense (BDNF-AS) has been found to be dysregulated in Huntington's Disease. However, the function of BDNF-AS in Parkinson's disease (PD) remains unknown. The purpose of this present study was to explore the effect of BDNF-AS on PD and its underlying molecular mechanisms.

METHODS

The MPTP-induced mouse model of PD and MPP+-induced SH-SY5Y cell model were established. Immunofluorescence was performed to determine the number of TH + positive cells. Mice behavioral changes were detected by pole and rota-rod test. SH-SY5Y cells viability, apoptosis was detected by MTT assay and flow cytometry. The number of autophagosome was measured by transmission electron microscopy. Dopamine content was tested by high performance liquid chromatography. Dual-luciferase reporter gene assay was utilized to verify the correlation between BDNF-AS and miR-125b-5p. qRT-PCR and western blot were used to detect gene expression levels.

RESULTS

Our results showed that BDNF-AS was up-regulated in MPTP-induced PD model and dopamine neurons, and MPP + treated SH-SY5Y cells, while miR-125b-5p was down-regulated. The expression of BDNF-AS was positively related with the MPP + concentration. BDNF-AS knockdown could significantly promote cell proliferation, while inhibit apoptosis and autophagy in SH-SY5Y cells treated by MPP + . Silencing BDNF-AS could also increase TH positive neurons and significantly suppress the autophagy of PD mice. Additionally, miR-125b-5p, a putative target gene of BDNF-AS, was involved in the effects of BDNF-AS on SH-SY5Y cell apoptosis and autophagy.

CONCLUSIONS

Our study demonstrated that knockdown of BDNF-AS could elevate SH-SY5Y cell viability, inhibit autophagy and apoptosis in MPTP-induced PD models through regulating miR-125b-5p, suggesting that BDNF-AS might act as a potential therapeutic target for PD.

Generation of a Novel Mouse Model of Parkinson's Disease via Targeted Knockdown of Glutamate Transporter GLT-1 in the Substantia Nigra

Parkinson's disease (PD) is a common neurodegenerative disease that is characterized by pathological dopaminergic (DA) neuronal death and α-synuclein aggregation. Glutamate excitotoxicity is a well-established pathogenesis of PD that involves dysfunctional expression of glutamate transporters. Glutamate transporter-1 (GLT-1) is mainly responsible for clearance of glutamate at synapses, including DA synapses. However, the role of GLT-1 in the aberrant synaptic transmission in PD remains elusive. In the present study, we generated small-interfering RNAs (siRNAs) to knockdown GLT-1 expression in primary astrocytes, and we report that siRNA knockdown of astrocytic GLT-1 decreased postsynaptic density-95 (PSD-95) expression in neuron-astrocyte cocultures in vitro. Using adeno-associated viruses (AAVs) targeting GLT-1 short-hairpin RNA (shRNA) sequences with a glial fibrillary acidic protein (GFAP) promoter, we abolished astrocytic GLT-1 expression in the substantia nigra pars compacta (SNpc) of mice. We found that GLT-1 deficiency in the SNpc induced parkinsonian phenotypes in terms of progressive motor deficits and nigral DA neuronal death in mice. We also found that there were reactive astrocytes and microglia in the SNpc upon GLT-1 knockdown. Furthermore, we used RNA sequencing to determine altered gene expression patterns upon GLT-1 knockdown in the SNpc, which revealed that disrupted calcium signaling pathways may be responsible for GLT-1 deficiency-mediated DA neuronal death in the SNpc. Taken together, our findings provide evidence for a novel role of GLT-1 in parkinsonian phenotypes in mice, which may contribute to further elucidation of the mechanisms of PD pathogenesis.

MiR-326 targets MDK to regulate the progression of cardiac hypertrophy through blocking JAK/STAT and MAPK signaling pathways

Cardiac hypertrophy is a heart reaction to the increase of cardiac load, with the characteristics of increased expression of cardiac hypertrophy markers, enhanced protein synthesis, and enlarged cell area. However, molecular mechanisms in cardiac hypertrophy are still poorly substantiated. It has been reported that miRNAs can modulate human diseases, among which miR-326 has been reported as a biological regulator in human cancers, but its role in cardiac hypertrophy is rarely explored. This study focused on the exploration of the potential of miR-326 in cardiac hypertrophy. Our data revealed the downregulation of miR-326 in the TAC-induced hypertrophic mice and the Ang II-induced hypertrophic H9c2 cells. Functionally, miR-326 attenuated the effect of Ang II on cardiac hypertrophy in vitro. In addition, miR-326 negatively regulated JAK/STAT and MAPK signaling pathways. Mechanistically, miR-326 targeted and inhibited MDK to induce JAK/STAT and MAPK pathways. Rescue assays certified that miR-326 attenuated cardiac hypertrophy through targeting MDK and inhibiting JAK/STAT and MAPK signaling pathways. In brief, our study unveiled that miR-326 targets MDK to regulate the progression of cardiac hypertrophy through blocking JAK/STAT and MAPK signaling pathways, indicating that targeting miR-326 as a potential approach for cardiac hypertrophy treatment.

Functional Analysis of the 3' Untranslated Region of the Human GRIN1 Gene in Regulating Gene Expression in vitro

PURPOSE

Abnormal expression of the NR1 subunit of the N-methyl-d-aspartate (NMDA) receptor may potentially increase the susceptibility to neuropsychiatric diseases. The purpose of this study was to investigate the functional sequence of the 3'UTR of the human GRIN1 gene, which encodes the GluN1 receptor to determine the effect on the expression of GluN1 receptor.

METHODS

We transferred seven recombinant pmirGLO recombinant vectors containing the 3'UTR truncated fragment of the GRIN1 gene into HEK-293, SK-N-SH, and U87 cell lines and compared the relative fluorescence intensity of adjacent length fragments. The TargetScan database was used to predict miRNAs. Then, miRNA mimics/inhibitors were co-transfected into the three cell lines with the 3'UTR of GRIN1 (pmirGLO - GRIN1), to investigate their influence on GRIN1 gene expression.

RESULTS

Compared with the pmirGLo-Basic vector, the relative fluorescence intensity of the complete GRIN1 gene 3'UTR recombinant sequence -27 bp - +1284 bp (the next base of the stop codon is +1) was significantly decreased in all three cell lines. The relative fluorescence intensities were significantly different between -27 bp - +294 bp and -27 bp - +497 bp regions, and between -27 bp - +708 bp and -27 bp - +907 bp regions. According to the prediction of the TargetScan database and analysis, miR-212-5p, miR-324-3p and miR-326 may bind to +295 bp - +497 bp, while miR-491-5p may bind to +798 bp - +907 bp. After co-transfection of miRNA mimic/inhibitor or mimic/inhibitor NC with a recombinant vector in the 3'UTR region of GRIN1 gene, we found that has-miR-491-5p inhibited GRIN1 expression significantly in all three cell lines, while has-miR-326 inhibitor upregulated GRIN1 expression in HEK-293 and U87 cells.

CONCLUSION

miR-491-5p may bind to the 3'UTR of the GRIN1 gene (+799 bp - +805 bp, the next base of the stop codon is +1) and down-regulate gene expression in HEK-293, SK-N-SH, and U87 cell lines, which implicates a potential role of miR-491-5p in central nervous system diseases.

Apelin-36 mediates neuroprotective effects by regulating oxidative stress, autophagy and apoptosis in MPTP-induced Parkinson's disease model mice

Parkinson's disease (PD), a common human neurodegenerative disorder, is characterized by the presence of intraneuronal Lewy bodies composed principally of abnormal aggregated and post-translationally modified α-synuclein. In our previous research, we have demonstrated the neuroprotective effect of Apelin-36, a neuroendocrine peptide in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP)-lesioned PD model mice. Therefore, this study was designed to evaluate the neuroprotective mechanism of Apelin-36 against MPTP-induced neurotoxicity in mice. The results showed that MPTP-induced the depletion of dopamine in the striatum (STR) was partially reversed by Apelin-36. Apelin-36 also improved the activity of antioxidant system including superoxide dismutase (SOD) and glutathione (GSH), and decreased the overproduction of malondialdehyde (MDA) in the substantia nigra pars compacta (SNpc) and STR of MPTP-treated mice. Moreover, Apelin-36 downregulated inducible nitric oxide synthase (iNOS) and nitrated α-synuclein expression. Furthermore, Apelin-36 significantly promoted autophagy indicated by the up-regulation of LC3-II and Beclin1 and inhibition of p62 expression in the SNpc and STR of MPTP-treated mice. The protective effect of Apelin-36 was also associated with the inhibition of the apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) signaling pathway and inactivation of caspase-3. Taken together, our findings demonstrated that the neuroprotective mechanism of Apelin-36 against MPTP-induced neurotoxicity in mice might be related to decreasing the aggregation of nitrated α-synuclein and alleviating oxidative stress as well as promoting autophagy and inhibiting ASK1/JNK/caspase-3 apoptotic pathway, which provides a novel strategy for PD treatment.