miR-425 deficiency promotes necroptosis and dopaminergic neurodegeneration in Parkinson's disease

Mechanistic Evaluation of miRNAs and Their Targeted Genes in the Pathogenesis and Therapeutics of Parkinson's Disease

MicroRNA (miRNA) are usually 18-25 nucleotides long non-coding RNA targeting post-transcriptional regulation of genes involved in various biological processes. The function of miRNA is essential for maintaining a homeostatic cellular condition, regulating autophagy, cellular motility, and inflammation. Dysregulation of miRNA is responsible for multiple disorders, including neurodegeneration, which has emerged as a severe problem in recent times and has verified itself as a life-threatening condition that can be understood by the continuous destruction of neurons affecting various cognitive and motor functions. Parkinson's disease (PD) is the second most common, permanently debilitating neurodegenerative disorder after Alzheimer's, mainly characterized by uncontrolled tremor, stiffness, bradykinesia or akinesia (slowness in movement), and post-traumatic stress disorder. PD is mainly caused by the demolition of the primary dopamine neurotransmitter secretory cells and dopaminergic or dopamine secretory neurons in the substantia nigra pars compacta of the midbrain, which are majorly responsible for motor functions. In this study, a systematic evaluation of research articles from year 2017 to 2022 was performed on multiple search engines, and lists of miRNA being dysregulated in PD in different body components were generated. This study highlighted miR-7, miR-124, miR-29 family, and miR-425, showing altered expression levels during PD's progression, further regulating the expression of multiple genes responsible for PD.

miR-101a-3p/ROCK2 axis regulates neuronal injury in Parkinson's disease models

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). This study focuses on deciphering the role of microRNA (miR)-101a-3p in the neuronal injury of PD and its regulatory mechanism.

METHODS

We constructed a mouse model of PD by intraperitoneal injection of 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine hydrochloride (MPTP), and used 1-methyl-4-phenylpyridinium (MPP+) to treat Neuro-2a cells to construct an in-vitro PD model. Neurological dysfunction in mice was evaluated by swimming test and traction test. qRT-PCR was utilized to examine miR-101a-3p expression and ROCK2 expression in mouse brain tissues and Neuro-2a cells. Western blot was conducted to detect the expression of α-synuclein protein and ROCK2 in mouse brain tissues and Neuro-2a cells. The targeting relationship between miR-101a-3p and ROCK2 was determined by dual-luciferase reporter gene assay. The apoptosis of neuro-2a cells was assessed by flow cytometry.

RESULTS

Low miR-101a-3p expression and high ROCK2 expression were found in the brain tissues of PD mice and MPP+-treated Neuro-2a cells; PD mice showed decreased neurological disorders, and apoptosis of Neuro-2a cells was increased after MPP+ treatment, both of which were accompanied by increased accumulation of α-synuclein protein. After miR-101a-3p was overexpressed, the neurological function of PD mice was improved, and the apoptosis of Neuro-2a cells induced by MPP+ was alleviated, and the accumulation of α-synuclein protein was reduced; ROCK2 overexpression counteracted the protective effect of miR-101a-3p. Additionally, ROCK2 was identified as the direct target of miR-101a-3p.

CONCLUSION

MiR-101a-3p can reduce neuronal apoptosis and neurological deficit in PD mice by inhibiting ROCK2 expression, suggesting that miR-101a-3p is a promising therapeutic target for PD.

Noncoding RNAs: the crucial role of programmed cell death in osteoporosis

Osteoporosis is the most common skeletal disease characterized by an imbalance between bone resorption and bone remodeling. Osteoporosis can lead to bone loss and bone microstructural deterioration. This increases the risk of bone fragility and fracture, severely reducing patients' mobility and quality of life. However, the specific molecular mechanisms involved in the development of osteoporosis remain unclear. Increasing evidence suggests that multiple noncoding RNAs show differential expression in the osteoporosis state. Meanwhile, noncoding RNAs have been associated with an increased risk of osteoporosis and fracture. Noncoding RNAs are an important class of factors at the level of gene regulation and are mainly involved in cell proliferation, cell differentiation, and cell death. Programmed cell death is a genetically-regulated form of cell death involved in regulating the homeostasis of the internal environment. Noncoding RNA plays an important role in the programmed cell death process. The exploration of the noncoding RNA-programmed cell death axis has become an interesting area of research and has been shown to play a role in many diseases such as osteoporosis. In this review, we summarize the latest findings on the mechanism of noncoding RNA-mediated programmed cell death on bone homeostasis imbalance leading to osteoporosis. And we provide a deeper understanding of the role played by the noncoding RNA-programmed cell death axis at the gene regulatory level of osteoporosis. We hope to provide a unique opportunity to develop novel diagnostic and therapeutic approaches for osteoporosis.

5-Hydroxytryptamine 4 Receptor Agonist Attenuates Diabetic Enteric Neuropathy through Inhibition of the Receptor-Interacting Protein Kinase 3 Pathway

Necroptosis, considered as a form of programmed cell death, contributes to neural loss. The 5-hydroxytryptamine 4 receptor (5-HT4R) is involved in neurogenesis in the enteric nervous system. However, whether the activation of 5-HT4R can alleviate diabetic enteric neuropathy by inhibiting receptor-interacting protein kinase 3 (RIPK3)-mediated necroptosis is unclear. This study aimed to explore the beneficial effects of 5-HT4R agonist on enteric neuropathy in a mouse model of diabetes and the mechanisms underlying these effects. Diabetes developed neural loss in the colon of mice. 5-HT4Rs localized in submucosal and myenteric plexuses were confirmed. Administration of 5-HT4R agonist attenuated diabetes-induced colonic hypomotility and neural loss of the colon in mice. Remarkably, RIPK3, phosphorylated RIPK3, and its downstream target mixed lineage kinase domain-like protein (MLKL), two key proteins regulating necroptosis, were significantly up-regulated in the colon of diabetic mice. Treatment with 5-HT4R agonist appeared to inhibit diabetes-induced elevation of RIPK3, phosphorylated RIPK3, and MLKL in the colon of mice. Diabetes-induced up-regulation of MLKL in both the mucosa and the muscularis of the colon was prevented by Ripk3 deletion. Moreover, diabetes-evoked neural loss and delayed colonic transit were significantly inhibited by Ripk3 removal. These findings suggest that activation of 5-HT4Rs could potentially provide a protective effect against diabetic enteric neuropathy by suppressing RIPK3-mediated necroptosis.

Tumor Suppressor MicroRNAs in Clinical and Preclinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases in humans. We developed the concept called the "Aberrant Cell Cycle Disease (ACCD)" due to the accumulating evidence that shows that two different diseases share the common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncoprotein activation and tumor suppressor (TS) inactivation, which are associated with both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase/oncogene inhibition and TS elevation) can be leveraged for neurological treatments. MicroRNA (miR/miRNA) provides a new style of drug-target binding. For example, a single tumor suppressor miRNA (TS-miR/miRNA) can bind to and decrease tens of target kinases/oncogenes, producing much more robust efficacy to block cell cycle re-entry than inhibiting a single kinase/oncogene. In this review, we summarize the miRNAs that are altered in both cancers and neurological disorders, with an emphasis on miRNA drugs that have entered into clinical trials for neurological treatment.

Dopaminergic neuronal death via necroptosis in Parkinson's disease: A review of the literature

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive dysfunction and loss of dopaminergic neurons of the substantia nigra pars compacta (SNc). Several pathways of programmed cell death are likely to play a role in dopaminergic neuron death, such as apoptosis, necrosis, pyroptosis and ferroptosis, as well as cell death associated with proteasomal and mitochondrial dysfunction. A better understanding of the molecular mechanisms underlying dopaminergic neuron death could inform the design of drugs that promote neuron survival. Necroptosis is a recently characterized regulated cell death mechanism that exhibits morphological features common to both apoptosis and necrosis. It requires activation of an intracellular pathway involving receptor-interacting protein 1 kinase (RIP1 kinase, RIPK1), receptor-interacting protein 3 kinase (RIP3 kinase, RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL). The potential involvement of this programmed cell death pathway in the pathogenesis of PD has been studied by analysing biomarkers for necroptosis, such as the levels and oligomerization of phosphorylated RIPK3 (pRIPK3) and phosphorylated MLKL (pMLKL), in several PD preclinical models and in PD human tissue. Although there is evidence that other types of cell death also have a role in DA neuron death, most studies support the hypothesis that this cell death mechanism is activated in PD tissues. Drugs that prevent or reduce necroptosis may provide neuroprotection for PD. In this review, we summarize the findings from these studies. We also discuss how manipulating necroptosis might open a novel therapeutic approach to reduce neuronal degeneration in PD.

Identification of necroptosis-associated miRNA signature for predicting prognosis and immune landscape in stomach adenocarcinoma

PURPOSE

This study aims to identify the potential necroptosis related genes (NRGs)-associated miRNAs signature and explore the impact on the prognosis of stomach adenocarcinoma (STAD).

METHODS

Employing rigorous methodologies, we utilized univariate Cox, Lasso and multivariate Cox regression analyses to develop a prognostic signature. Kaplan-Meier (K-M) and ROC curves were applied to assess the prognostic value of signature in a training group and an independent test group. Furthermore, we conducted Gene Set Enrichment Analysis (GSEA) for enrichment of tumor-related pathways. The risk score was calculated for each patient based on the expression of miRNAs which were enrolled in the signature. Patients were stratified into high- and low-risk groups. The immune cell infiltration and immunotherapy were compared between the two groups. Finally, the diagnostic potential of the miRNA was explored by RT-qPCR.

RESULTS

We constructed a prognostic model based on 6 NRGs-associated miRNAs. K-M plots underscored superior survival outcomes in the low-risk group. GSEA results revealed the enrichment of several tumor-related pathways in the high-risk group. Notably, CD8+ T cells, Tregs and activated memory CD4+ T cells exhibited negative correlations with the risk score. Additionally, a few immune checkpoint genes, such as CTLA4, PD1 and PD-L1, were significantly upregulated in the low-risk group. Furthermore, the serum expression levels of all these 6 miRNAs were significantly elevated in STAD patients.

CONCLUSIONS

Our study identified a robust risk score derived from a signature of 6 NRGs-associated miRNAs, demonstrating high efficacy for prognosis of STAD. These results not only contributed to our understanding of STAD pathogenesis, but also held promise for potential clinical applications, particularly in the realm of personalized immunotherapy for STAD patients.

MicroRNA-218-5p-Ddx41 axis restrains microglia-mediated neuroinflammation through downregulating type I interferon response in a mouse model of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic (DA) neurons in the substantia nigra (SN). Microglia-mediated neuroinflammation has been largely considered one of main factors to the PD pathology. MicroRNA-218-5p (miR-218-5p) is a microRNA that plays a role in neurodevelopment and function, while its potential function in PD and neuroinflammation remains unclear.

METHODS

We explore the involvement of miR-218-5p in the PD in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model. The miR-218-5p agomir used for overexpression was delivered into the substantia nigra (SN) by bilateral stereotaxic infusions. The loss of dopaminergic (DA) neurons and microglial inflammation in the SN was determined using Western blotting and immunofluorescence. Motor function was assessed using the rotarod test. RNA sequencing (RNA-seq) was performed to explore the pathways regulated by miR-218-5p. The target genes of miR-218-5p were predicted using TargetScan and confirmed using dual luciferase reporter assays. The effects of miR-218-5p on microglial inflammation and related pathways were verified in murine microglia-like BV2 cells. To stimulate BV2 cells, SH-SY5Y cells were treated with 1-methyl-4-phenylpyridinium (MPP+) and the conditioned media (CM) were collected.

RESULTS

MiR-218-5p expression was reduced in both the SN of MPTP-induced mice and MPP+-treated BV2 cells. MiR-218-5p overexpression significantly alleviated MPTP-induced microglial inflammation, loss of DA neurons, and motor dysfunction. RNA sequence and gene set enrichment analysis showed that type I interferon (IFN-I) pathways were upregulated in MPTP-induced mice, while this upregulation was reversed by miR-218-5p overexpression. A luciferase reporter assay verified that Ddx41 was a target gene of miR-218-5p. In vitro, miR-218-5p overexpression or Ddx41 knockdown inhibited the IFN-I response and expression of inflammatory cytokines in BV2 cells stimulated with MPP+-CM.

CONCLUSIONS

MiR-218-5p suppresses microglia-mediated neuroinflammation and preserves DA neurons via Ddx41/IFN-I. Hence, miR-218-5p-Ddx41 is a promising therapeutic target for PD.

Tracheal epithelial cell-exosome-derived MiR-21-5p inhibits alveolar macrophage pyroptosis to resist pulmonary bacterial infection through PIK3CD-autophagy pathway

AIMS

Structural cells play an important role in regulating immune cells during infection. Our aim was to determine whether structural porcine tracheal epithelial cells (PTECs) can regulate alveolar macrophages (AMs) to prevent bacterial pneumonia, explore the underlying mechanism(s) and therapeutic target.

MATERIALS AND METHODS

Actinobacillus pleuropneumoniae (APP) was used as the model strain for infection studies. Small RNA sequencing was used to identify differentially abundant exosome-derived miRNAs. The role of PTECs exosome-derived miR-21-5p in regulating AMs autophagy, pyroptosis, reactive oxygen species (ROS) was determined using RT-qPCR, western-blotting, flow cytometry, immunohistochemistry. Luciferase reporter assays were conducted to identify potential binding targets of miR-21-5p. The universality of miR-21-5p action on resistance to bacterial pulmonary infection was demonstrated using Klebsiella pneumoniae or Staphylococcus aureus in vitro and in vivo infection models.

KEY FINDINGS

MiR-21-5p was enriched in PETCs-derived exosomes, which protected AMs against pulmonary bacterial infection. Mechanistically, miR-21-5p targeted PIK3CD, to promote autophagy of AMs, which reduced the pyroptosis induced by APP infection via inhibiting the over-production of ROS, which in turn suppressed the over-expression of pro-inflammatory cytokines, and increased bacterial clearance. Importantly, the protective effect and mechanism of miR-21-5p were universal as they also occurred upon challenge with Klebsiella pneumoniae and Staphylococcus aureus.

SIGNIFICANCE

Our data reveals miR-21-5p can promote pulmonary resistance to bacterial infection by inhibiting pyroptosis of alveolar macrophages through the PIK3CD-autophagy-ROS pathway, suggesting PIK3CD may be a potential therapeutic target for bacterial pneumonia.

Unraveling the role of miRNAs in the diagnosis, progression, and therapeutic intervention of Parkinson's disease

Parkinson's disease (PD) is a debilitating neurological disorder characterized by the impairment of the motor system, resulting in symptoms such as resting tremor, cogwheel rigidity, bradykinesia, difficulty with gait, and postural instability. The occurrence of striatal dopamine insufficiency can be attributed to a notable decline in dopaminergic neurons inside the substantia nigra pars compacta. Additionally, the development of Lewy bodies serves as a pathological hallmark of PD. While current therapy approaches for PD aim to preserve dopaminergic neurons or replenish dopamine levels in the brain, it is important to acknowledge that achieving complete remission of the condition remains elusive. MicroRNAs (miRNAs, miR) are a class of small, non-coding ribonucleic acids involved in regulating gene expression at the post-transcriptional level. The miRNAs play a crucial part in the underlying pathogenic mechanisms of several neurodegenerative illnesses, including PD. The aim of this review is to explore the role of miRNAs in regulating genes associated with the onset and progression of PD, investigate the potential of miRNAs as a diagnostic tool, assess the effectiveness of targeting specific miRNAs as an alternative therapeutic strategy to impede disease advancement, and discuss the utilization of newly developed nanoparticles for delivering miRNAs as neurodegenerative therapies.

MLKL deficiency alleviates neuroinflammation and motor deficits in the α-synuclein transgenic mouse model of Parkinson's disease

Parkinson's disease (PD), one of the most devastating neurodegenerative brain disorders, is characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN) and deposits of α-synuclein aggregates. Currently, pharmacological interventions for PD remain inadequate. The cell necroptosis executor protein MLKL (Mixed-lineage kinase domain-like) is involved in various diseases, including inflammatory bowel disease and neurodegenerative diseases; however, its precise role in PD remains unclear. Here, we investigated the neuroprotective role of MLKL inhibition or ablation against primary neuronal cells and human iPSC-derived midbrain organoids induced by toxic α-Synuclein preformed fibrils (PFFs). Using a mouse model (Tg-Mlkl-/-) generated by crossbreeding the SNCA A53T synuclein transgenic mice with MLKL knockout (KO)mice, we assessed the impact of MLKL deficiency on the progression of Parkinsonian traits. Our findings demonstrate that Tg-Mlkl-/- mice exhibited a significant improvement in motor symptoms and reduced phosphorylated α-synuclein expression compared to the classic A53T transgenic mice. Furthermore, MLKL deficiency alleviated tyrosine hydroxylase (TH)-positive neuron loss and attenuated neuroinflammation by inhibiting the activation of microglia and astrocytes. Single-cell RNA-seq (scRNA-seq) analysis of the SN of Tg-Mlkl-/- mice revealed a unique cell type-specific transcriptome profile, including downregulated prostaglandin D synthase (PTGDS) expression, indicating reduced microglial cells and dampened neuron death. Thus, MLKL represents a critical therapeutic target for reducing neuroinflammation and preventing motor deficits in PD.

Novel, non-conventional pathways of necroptosis in the heart and other organs: Molecular mechanisms, regulation and inter-organelle interplay

Necroptosis, a cell death modality that is defined as a necrosis-like cell death depending on the receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL), has been found to underlie the injury of various organs. Nevertheless, the molecular background of this cell loss seems to also involve, at least under certain circumstances, some novel axes, such as RIPK3-PGAM5-Drp1 (mitochondrial protein phosphatase 5-dynamin-related protein 1), RIPK3-CaMKII (Ca2+/calmodulin-dependent protein kinase II) and RIPK3-JNK-BNIP3 (c-Jun N-terminal kinase-BCL2 Interacting Protein 3). In addition, endoplasmic reticulum stress and oxidative stress via the higher production of reactive oxygen species produced by the mitochondrial enzymes and the enzymes of the plasma membrane have been implicated in necroptosis, thereby depicting an inter-organelle interplay in the mechanisms of this cell death. However, the role and relationship between these novel non-conventional signalling and the well-accepted canonical pathway in terms of tissue- and/or disease-specific prioritisation is completely unknown. In this review, we provide current knowledge on some necroptotic pathways being not directly associated with RIPK3-MLKL execution and report studies showing the role of respective microRNAs in the regulation of necroptotic injury in the heart and in some other tissues having a high expression of the pro-necroptotic proteins.

Targeting epigenetic modifications in Parkinson's disease therapy

Parkinson's disease (PD) is a multifactorial disease due to a complex interplay between genetic and epigenetic factors. Recent efforts shed new light on the epigenetic mechanisms involved in regulating pathways related to the development of PD, including DNA methylation, posttranslational modifications of histones, and the presence of microRNA (miRNA or miR). Epigenetic regulators are potential therapeutic targets for neurodegenerative disorders. In the review, we aim to summarize mechanisms of epigenetic regulation in PD, and describe how the DNA methyltransferases, histone deacetylases, and histone acetyltransferases that mediate the key processes of PD are attractive therapeutic targets. We discuss the use of inhibitors and/or activators of these regulators in PD models or patients, and how these small molecule epigenetic modulators elicit neuroprotective effects. Further more, given the importance of miRNAs in PD, their contributions to the underlying mechanisms of PD will be discussed as well, together with miRNA-based therapies.

Induction Mechanism of Ferroptosis, Necroptosis, and Pyroptosis: A Novel Therapeutic Target in Nervous System Diseases

In recent years, three emerging cell deaths, ferroptosis, necroptosis and pyroptosis, have gradually attracted everyone's attention, and they also play an important role in the occurrence and development of various diseases. Ferroptosis is an idiographic iron-dependent form regulated cell death with the hallmark of accumulation of the intracellular reactive oxygen species (ROS). Necroptosis is a form of regulated necrotic cell death mediated by the receptor-interacting protein kinase 1(RIPK1) and receptor-interacting protein kinase 3RIPK3. Pyroptosis, also known as cell inflammatory necrosis, is a programmed cell necrosis mediated by Gasdermin D (GSDMD). It is manifested by the continuous swelling of the cells until the cell membrane ruptures, resulting in the release of the cell contents and the activation of a strong inflammatory response. Neurological disorders remain a clinical challenge and patients do not respond well to conventional treatments. Nerve cell death can aggravate the occurrence and development of neurological diseases. This article reviews the specific mechanisms of these three types of cell death and their relationship with neurological diseases and the evidence for the role of the three types of cell death in neurological diseases; understanding these pathways and their mechanisms is helpful for the treatment of neurological diseases.

RIPK1-Induced A1 Reactive Astrocytes in Brain in MPTP-Treated Murine Model of Parkinson's Disease

Neuroinflammation is one of the hallmarks of Parkinson's disease, including the massive activation of microglia and astrocytes and the release of inflammatory factors. Receptor-interacting protein kinase 1 (RIPK1) is reported to mediate cell death and inflammatory signaling, and is markedly elevated in the brain in PD mouse models. Here, we aim to explore the role of RIPK1 in regulating the neuroinflammation of PD. C57BL/6J mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 20 mg/kg four times/day), followed by necrostatin-1 treatment (Nec-1, RIPK1 inhibitor; 1.65 mg/kg once daily for seven days. Notably, the first Nec-1 was given 12 h before MPTP modeling). Behavioral tests indicated that inhibition of RIPK1 greatly relieved motor dysfunction and anxiety-like behaviors of PD mice. It also increased striatal TH expression, rescue the loss of dopaminergic neurons, and reduce activation of astrocytes in the striatum of PD mice. Furthermore, inhibition of RIPK1 expression reduced A1 astrocytes' relative gene expression (CFB, H2-T23) and inflammatory cytokine or chemokine production (CCL2, TNF-α, IL-1β) in the striatum of PD mice. Collectively, inhibition of RIPK1 expression can provide neuroprotection to PD mice, probably through inhibition of the astrocyte A1 phenotype, and thus RIPK1 might be an important target in PD treatment.

MicroRNAs in Age-Related Proteostasis and Stress Responses

Aging is associated with the accumulation of damaged and misfolded proteins through a decline in the protein homeostasis (proteostasis) machinery, leading to various age-associated protein misfolding diseases such as Huntington's or Parkinson's. The efficiency of cellular stress response pathways also weakens with age, further contributing to the failure to maintain proteostasis. MicroRNAs (miRNAs or miRs) are a class of small, non-coding RNAs (ncRNAs) that bind target messenger RNAs at their 3'UTR, resulting in the post-transcriptional repression of gene expression. From the discovery of aging roles for lin-4 in C. elegans, the role of numerous miRNAs in controlling the aging process has been uncovered in different organisms. Recent studies have also shown that miRNAs regulate different components of proteostasis machinery as well as cellular response pathways to proteotoxic stress, some of which are very important during aging or in age-related pathologies. Here, we present a review of these findings, highlighting the role of individual miRNAs in age-associated protein folding and degradation across different organisms. We also broadly summarize the relationships between miRNAs and organelle-specific stress response pathways during aging and in various age-associated diseases.

Unwinding the modalities of necrosome activation and necroptosis machinery in neurological diseases

Necroptosis, a regulated form of cell death, is involved in the genesis and development of various life-threatening diseases, including cancer, neurological disorders, cardiac myopathy, and diabetes. Necroptosis initiates with the formation and activation of a necrosome complex, which consists of RIPK1, RIPK2, RIPK3, and MLKL. Emerging studies has demonstrated the regulation of the necroptosis cell death pathway through the implication of numerous post-translational modifications, namely ubiquitination, acetylation, methylation, SUMOylation, hydroxylation, and others. In addition, the negative regulation of the necroptosis pathway has been shown to interfere with brain homeostasis through the regulation of axonal degeneration, mitochondrial dynamics, lysosomal defects, and inflammatory response. Necroptosis is controlled by the activity and expression of signaling molecules, namely VEGF/VEGFR, PI3K/Akt/GSK-3β, c-Jun N-terminal kinases (JNK), ERK/MAPK, and Wnt/β-catenin. Herein, we briefly discussed the implication and potential of necrosome activation in the pathogenesis and progression of neurological manifestations, such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, traumatic brain injury, and others. Further, we present a detailed picture of natural compounds, micro-RNAs, and chemical compounds as therapeutic agents for treating neurological manifestations.

Integration of miRNA's Theranostic Potential with Nanotechnology: Promises and Challenges for Parkinson's Disease Therapeutics

Despite the wide research going on in Parkinson's disease (PD), the burden of PD still remains high and continues to increase. The current drugs available for the treatment of PD are only aimed at symptomatic control. Hence, research is mainly focused on identifying the novel therapeutic targets that can be effectively targeted in order to slow down or culminate the disease progression. Recently the role of microRNAs (miRNAs) in the regulation of various pathological mechanisms of PD has been thoroughly explored and many of them were found to be dysregulated in the biological samples of PD patients. These miRNAs can be used as diagnostic markers and novel therapeutic options to manage PD. The delivery of miRNAs to the target site in brain is a challenging job owing to their nature of degradability by endonucleases as well as poor blood brain barrier (BBB) permeability. Nanoparticles appear to be the best solution to effectively encase the miRNA in their core as well as cross the BBB to deliver them into brain. Functionalisation of these nanoparticles further enhances the site-specific delivery.

Promising biomarkers and therapeutic targets for the management of Parkinson's disease: recent advancements and contemporary research

Parkinson's disease (PD) is one of the progressive neurological diseases which affect around 10 million population worldwide. The clinical manifestation of motor symptoms in PD patients appears later when most dopaminergic neurons have degenerated. Thus, for better management of PD, the development of accurate biomarkers for the early prognosis of PD is imperative. The present work will discuss the potential biomarkers from various attributes covering biochemical, microRNA, and neuroimaging aspects (α-synuclein, DJ-1, UCH-L1, β-glucocerebrosidase, BDNF, etc.) for diagnosis, recent development in PD management, and major limitations with current and conventional anti-Parkinson therapy. This manuscript summarizes potential biomarkers and therapeutic targets, based on available preclinical and clinical evidence, for better management of PD.

Necroptosis in CNS diseases: Focus on astrocytes

In the last few years, necroptosis, a recently described type of cell death, has been reported to play an important role in the development of various brain pathologies. Necroptosis is a cell death mechanism that has morphological characteristics similar to necrosis but is mediated by fundamentally different molecular pathways. Necroptosis is initiated by signaling through the interaction of RIP1/RIP3/MLKL proteins (receptor-interacting protein kinase 1/receptor-interacting protein kinase 3/mixed lineage kinase domain-like protein). RIPK1 kinase is usually inactive under physiological conditions. It is activated by stimulation of death receptors (TNFR1, TNFR2, TLR3, and 4, Fas-ligand) by external signals. Phosphorylation of RIPK1 results in the formation of its complex with death receptors. Further, complexes with the second member of the RIP3 and MLKL cascade appear, and the necroptosome is formed. There is enough evidence that necroptosis plays an important role in the pathogenesis of brain ischemia and neurodegenerative diseases. In recent years, a point of view that both neurons and glial cells can play a key role in the development of the central nervous system (CNS) pathologies finds more and more confirmation. Astrocytes play complex roles during neurodegeneration and ischemic brain damage initiating both impair and protective processes. However, the cellular and molecular mechanisms that induce pathogenic activity of astrocytes remain veiled. In this review, we consider these processes in terms of the initiation of necroptosis. On the other hand, it is important to remember that like other types of programmed cell death, necroptosis plays an important role for the organism, as it induces a strong immune response and is involved in the control of cancerogenesis. In this review, we provide an overview of the complex role of necroptosis as an important pathogenetic component of neuronal and astrocyte death in neurodegenerative diseases, epileptogenesis, and ischemic brain damage.

RIPK1 Regulates Microglial Activation in Lipopolysaccharide-Induced Neuroinflammation and MPTP-Induced Parkinson's Disease Mouse Models

Increasing evidence suggests a pivotal role of receptor-interacting protein kinase 1 (RIPK1), an initiator of necroptosis, in neuroinflammation. However, the precise role of RIPK1 in microglial activation remains unclear. In the present study, we explored the role of RIPK1 in lipopolysaccharide (LPS)-induced neuroinflammation and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice by using RIPK1-specific inhibitors necrostatin-1 (Nec-1) and necrostatin-1 stable (Nec-1s). Nec-1/Nec-1s or RIPK1 siRNA inhibited the production of proinflammatory molecules and the phosphorylation of RIPK1-RIPK3-MLKL and cell death in LPS-induced inflammatory or LPS/QVD/BV6-induced necroptotic conditions of BV2 microglial cells. Detailed mechanistic studies showed that Nec-1/Nec-1s exerted anti-inflammatory effects by modulating AMPK, PI3K/Akt, MAPKs, and NF-κB signaling pathways in LPS-stimulated BV2 cells. Subsequent in vivo studies showed that Nec-1/Nec-1s inhibited microglial activation and proinflammatory gene expression by inhibiting the RIPK1 phosphorylation in the brains of LPS-injected mice. Furthermore, Nec-1/Nec-1s exert neuroprotective and anti-inflammatory effects in MPTP-induced PD mice. We found that p-RIPK1 is mainly expressed in microglia, and thus RIPK1 may contribute to neuroinflammation and subsequent cell death of dopaminergic neurons in MPTP-induced PD model mice. These data suggest that RIPK1 is a key regulator of microglial activation in LPS-induced neuroinflammation and MPTP-induced PD mice.

Understanding the Involvement of microRNAs in Mitochondrial Dysfunction and Their Role as Potential Biomarkers and Therapeutic Targets in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting the elderly worldwide and causing significant movement impairments. The goal of PD treatment is to restore dopamine levels in the striatum and regulate movement symptoms. The lack of specific biomarkers for early diagnosis, as well as medication aimed at addressing the pathogenic mechanisms to decelerate the progression of dopaminergic neurodegeneration, are key roadblocks in the management of PD. Various pathogenic processes have been identified to be involved in the progression of PD, with mitochondrial dysfunction being a major contributor to the disease's pathogenesis. The regulation of mitochondrial functions is influenced by a variety of factors, including epigenetics. microRNAs (miRNAs) are epigenetic modulators involved in the regulation of gene expression and regulate a variety of proteins that essential for proper mitochondrial functioning. They are found to be dysregulated in PD, as evidenced by biological samples from PD patients and in vitro and in vivo research. In this article, we attempt to provide an overview of several miRNAs linked to mitochondrial dysfunction and their potential as diagnostic biomarkers and therapeutic targets in PD.

Role of Necroptosis in Central Nervous System Diseases

Necroptosis is a type of precisely regulated necrotic cell death activated in caspase-deficient conditions. Multiple factors initiate the necroptotic signaling pathway, including toll-like receptor 3/4, tumor necrosis factor (TNF), dsRNA viruses, and T cell receptors. Presently, TNF-induced necroptosis via the phosphorylation of three key proteins, receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, and mixed lineage kinase domain-like protein, is the best-characterized process. Necroptosis induced by Z-DNA-binding protein 1 (ZBP-1) and toll/interleukin-1 receptor (TIR)-domain-containing adapter-inducing interferon (TRIF) plays a significant role in infectious diseases, such as influenza A virus, Zika virus, and herpesvirus infection. An increasing number of studies have demonstrated the close association of necroptosis with multiple diseases, and disrupting necroptosis has been confirmed to be effective for treating (or managing) these diseases. The central nervous system (CNS) exhibits unique physiological structures and immune characteristics. Necroptosis may occur without the sequential activation of signal proteins, and the necroptosis of supporting cells has more important implications in disease development. Additionally, necroptotic signals can be activated in the absence of necroptosis. Here, we summarize the role of necroptosis and its signal proteins in CNS diseases and characterize typical necroptosis regulators to provide a basis for the further development of therapeutic strategies for treating such diseases. In the present review, relevant information has been consolidated from recent studies (from 2010 until the present), excluding the patents in this field.

miRNA and antisense oligonucleotide-based α-synuclein targeting as disease-modifying therapeutics in Parkinson's disease

α-synuclein is the synaptic protein majorly involved in neuronal dysfunction and death and it is well known for the last two decades as a hallmark of Parkinson's disease. Alpha-synuclein is involved in neurodegeneration mediated through various neurotoxic pathways, majorly including autophagy or lysosomal dysregulation, mitochondrial disruption, synaptic dysfunction, and oxidative stress. Moreover, the alpha-synuclein aggregation has been associated with the development of several neurodegenerative conditions such as various forms of Parkinson's disease. The recent discovery in oligonucleotide chemistry has developed potential alpha-synuclein targeting molecules for the treatment of neurodegenerative diseases. The present review article focuses on recent advances in the applications of oligonucleotides acting via alpha-synuclein targeting mechanisms and their implication in combating Parkinson's disease. Moreover, the article emphasizes the potential of miRNAs, and antisense oligonucleotides and the challenges associated with their use in the therapeutical management of Parkinson's disease.

MicroRNAs in the epigenetic regulation of disease progression in Parkinson’s disease

Parkinson’s disease (PD) is a multifactorial neurodegenerative condition with symptoms such as resting tremor, rigidity, bradykinesia (slowness of moment), and postural instability. Neuroinflammation plays a significant part in the onset and progression of neurodegeneration in a wide range of disorders, including PD. The loss of dopaminergic neurons in the substantia nigra (SN) is thought to be the primary cause of PD disease progression. However, other neurotransmitter systems like serotoninergic, glutamatergic, noradrenergic, adrenergic, cholinergic, tryptaminergic, and peptidergic appear to be affected as well. Epigenetic regulation of gene expression is emerging as an influencing factor in the pathophysiology of PD. In recent years, epigenetic regulation by microRNAs (miRNAs) has been discovered to play an important function in the disease progression of PD. This review explores the role of miRNAs and their signaling pathways in regulating gene expression from development through neurodegeneration and how these mechanisms are linked to the pathophysiology of PD, emphasizing potential therapeutic interventions.

Identification of Potential miRNA-mRNA Regulatory Network Contributing to Parkinson’s Disease

Parkinson's disease (PD) is a common neurodegenerative disease, and the mechanism underlying PD pathogenesis is not completely understood. Increasing evidence indicates that microRNAs (miRNAs) play a critical regulatory role in the pathogenesis of PD. This study aimed to explore the miRNA-mRNA regulatory network for PD. The differentially expressed miRNAs (DEmis) and genes (DEGs) between PD patients and healthy donors were screened from the miRNA dataset GSE16658 and mRNA dataset GSE100054 downloaded from the Gene Expression Omnibus (GEO) database. Target genes of the DEmis were selected when they were predicted by three or four online databases and overlapped with DEGs from GSE100054. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were then conducted by Database for Annotation, Visualization and Integrated Discovery (DAVID) and Metascape analytic tools. The correlation between the screened genes and PD was evaluated with the online tool Comparative Toxicogenomics Database (CTD), and protein-protein interaction (PPI) networks were built by the STRING platform. We further investigated the expression of genes in the miRNA-mRNA regulatory network in blood samples collected from PD patients and healthy donors via qRT-PCR. We identified 1505 upregulated and 1302 downregulated DEGs, and 77 upregulated and 112 downregulated DEmis were preliminarily screened from the GEO database. Further functional enrichment analysis identified 10 PD-related hub genes, including RAC1, IRS2, LEPR, PPARGC1A, CAMKK2, RAB10, RAB13, RAB27B, RAB11A, and JAK2, which were mainly involved in Rab protein signaling transduction, AMPK signaling pathway, and signaling by Leptin. A miRNA-mRNA regulatory network was then constructed with 10 hub genes, and their interacting miRNAs overlapped with DEmis, including miR-30e-5p, miR-142-3p, miR-101-3p, miR-32-3p, miR-508-5p, miR-642a-5p, miR-19a-3p, and miR-21-5p. Analysis of clinical samples verified significant upregulation of LEPR and downregulation of miR-101-3p and miR-30e-5p in PD patients as compared with healthy donors. Thus, the miRNA-mRNA regulatory network was initially constructed and has the potential to provide novel insights into the pathogenesis and treatment of PD.

Downregulated miRNAs associated with auditory deafferentation and compensatory neural plastic changes following single-sided deafness in the inferior colliculi of rats

BACKGROUND AND AIMS

Deafferentation and compensatory neural plastic changes in the inferior colliculus (IC) have been suggested following single-sided deafness (SSD). We explored related miRNA changes in the IC of SSD rats using miRNA microarray analyses.

METHODS

Eight-week-old rats were divided into control and SSD rats (n = 8 for each group). SSD rats underwent right-side cochlear ablation surgery, with the IC harvested two weeks post-surgery. miRNA microarray analysis was performed using GeneChip miRNA 4.0, microarray (Affymetrix Inc.). miRNAs whose expression levels differed between SSD and control rats with a fold-change ≥1.5 and P < 0.05 were examined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Target genes of differentially expressed miRNAs were predicted using TargetScan software. The pathways related to predicted target genes were analyzed. mRNA levels of predicted target genes were estimated using qRT-PCR.

RESULTS

The expression of miR-15b-5p, miR-202-5p, and miR-212-3p was lower in the contralateral (left) IC of SSD rats than that of control rats. In SSD rats, miRNA expression levels in the contralateral IC were 0.45-, 0.25-, and 0.50-fold lower for miR-15b-5p, miR-202-5p, and miR-212-3p, respectively (P < 0.05). The expression of predicted target genes (Spred1, Rasa1, Lsm11, and Srsf1) was higher in the contralateral IC of SSD rats than in control rats. The targets were predicted to be related with cleavage of growing transcripts in the termination region, mitogen-activated protein kinase family signaling cascades, RAF/AMP kinase cascade, regulation of RAS by GTPase activating proteins (GAPs), and RNA polymerase II transcription termination. For ipsilateral ICs, miR-425-3p, miR-199a-5p, and miR-134-3p showed lower expressions in SSD rats than in control rats, which were 0.55-, 0.61-, and 0.69-fold lower, respectively (P < 0.05). The expression of predicted target genes (Atp2b2, Grin2b, Foxp1, Ztbt20, Zfp91, and Strn) was higher in the ipsilateral IC of SSD rats; the regulation of synaptic plasticity, cAMP signaling pathway, metal ion binding, and calcium ion transport can be associated with these target genes.

CONCLUSION

Adult rats with unilateral auditory deprivation showed miRNA changes in the IC. The contralateral IC showed decreased miRNA expression predicted to be related to MAPK and RAS signaling, whereas the ipsilateral IC revealed decreased miRNA expression predicted to be associated with synaptic plasticity and calcium ion transport.

miR-494-3p Promotes Erastin-Induced Ferroptosis by Targeting REST to Activate the Interplay between SP1 and ACSL4 in Parkinson’s Disease

Background

Ferroptosis is a type of iron-dependent programmed cell death. Ferroptosis has been shown to be a significant factor for the pathogenesis of Parkinson's disease (PD). However, the mechanism involved in ferroptosis has not been fully elucidated in PD.

Methods

Repressor element-1 silencing transcription factor (REST) and specificity protein 1 (SP1) expressions were monitored by qRT-PCR. Cell viability, reactive oxygen species (ROS), and mitochondrial injury were validated by CCK-8, flow cytometry, and transmission electron microscope. The levels of neurons-related proteins and ferroptosis-associated proteins were identified by western blot and immunofluorescence assays. The interaction between miR-494-3p and REST or SP1 and ACSL4 was analyzed by luciferase, chromatin immunoprecipitation, or EMSA assay.

Results

Erastin could dose-dependently induce neuron injury and ferroptosis of LUHMES cells. miR-494-3p overexpression induced ROS production, mitochondrial damage, ferroptosis, and neuron injury in erastin-induced LUHMES cells. Likewise, miR-494-3p inhibition had the opposite effects. We also showed that REST was a target gene of miR-494-3p and could repress erastin-induced ferroptosis, neuron injury, ROS, and mitochondrial injury via SP1 in LUHMES cells. Moreover, we demonstrated that SP1 could interact with ACSL4. We also confirmed that miR-494-3p could aggravate the pathological changes of substantia nigra and corpus striatum in the MPTP-induced PD mouse model.

Conclusion

miR-494-3p significantly promotes ferroptosis by regulating the REST/SP1/ACSL4 axis in PD. Thus, our results open potential therapeutic targets for PD.

Ethnomedicinal plants used for the treatment of neurodegenerative diseases in Himachal Pradesh, India in Western Himalaya

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants are considered as a healthcare resource and widely used by rural people in their traditional medicine system for curing neurodegenerative diseases. Neurodegenerative diseases refer to incurable and debilitating conditions that result in progressive degeneration/death of nerve cells or neurons in the human brain. This review is mainly focused on the usage of different ethnomedicinal plants in the treatment of different neurodegenerative diseases in Himachal Pradesh. Study reveals total of 73 ethnomedicinal plants, which are used for treating different neurological disorders in different areas of Himachal Pradesh. The data is compiled from the different sources that described the detailed information of plants in tabular form and highlights the significance of different phytochemicals on neuroprotective function. The present study also provides the scientific data and clinical (in-vivo and in-vitro) studies in support of ethnomedicinal use.

AIM OF THE STUDY

This review aims to provide information of ethnomedicinal plants which are used for the treatment of neurodegenerative diseases in Himachal Pradesh.

MATERIALS AND METHODS

Information on the use of ethnomedicinal plants to treat various neurological disorders has been gathered from a variety of sources, including various types of literature, books, and relevant publications in Google Scholar, Research Gate, Science Direct, Scopus, and Pub Med, among others. The collected data is tabulated, including the botanical names of plants, mode of use and the disease for which it is used for curing, etc. RESULTS: There are 73 ethnomedicinal plants that are used to cure various neurological disorders, with the most plants being used to treat epilepsy problem in Himachal Pradesh.

CONCLUSION

Numerous phytochemicals and extracts from diverse plants were found to have a protective effect against neurodegenerative diseases. Antioxidant activity is known to exist in a variety of herbal plants. The most common bioactive antioxidant chemicals having their significant impacts include flavonoids, flavones, coumarins, lignans, isoflavones, catechins, anthocyanins, and isocatechins.

Dysregulated miRNAs as Biomarkers and Therapeutical Targets in Neurodegenerative Diseases

Alzheimer’s disease (AD), Parkinson’s disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are representative neurodegenerative diseases (NDs) characterized by degeneration of selective neurons, as well as the lack of effective biomarkers and therapeutic treatments. In the last decade, microRNAs (miRNAs) have gained considerable interest in diagnostics and therapy of NDs, owing to their aberrant expression and their ability to target multiple molecules and pathways. Here, we provide an overview of dysregulated miRNAs in fluids (blood or cerebrospinal fluid) and nervous tissue of AD, PD, and ALS patients. By emphasizing those that are commonly dysregulated in these NDs, we highlight their potential role as biomarkers or therapeutical targets and describe the use of antisense oligonucleotides as miRNA therapies.

The Absence of Caspase-8 in the Dopaminergic System Leads to Mild Autism-like Behavior

In the last decade, new non-apoptotic roles have been ascribed to apoptotic caspases. This family of proteins plays an important role in the sculpting of the brain in the early stages of development by eliminating excessive and nonfunctional synapses and extra cells. Consequently, impairments in this process can underlie many neurological and mental illnesses. This view is particularly relevant to dopamine because it plays a pleiotropic role in motor control, motivation, and reward processing. In this study, we analyze the effects of the elimination of caspase-8 (CASP8) on the development of catecholaminergic neurons using neurochemical, ultrastructural, and behavioral tests. To do this, we selectively delete the CASP8 gene in cells that express tyrosine hydroxylase with the help of recombination through the Cre-loxP system. Our results show that the number of dopaminergic neurons increases in the substantia nigra. In the striatum, the basal extracellular level of dopamine and potassium-evoked dopamine release decreased significantly in mice lacking CASP8, clearly showing the low dopamine functioning in tissues innervated by this neurotransmitter. This view is supported by electron microscopy analysis of striatal synapses. Interestingly, behavioral analysis demonstrates that mice lacking CASP8 show changes reminiscent of autism spectrum disorders (ASD). Our research reactivates the possible role of dopamine transmission in the pathogenesis of ASD and provides a mild model of autism.

TNF-α derived from arsenite-induced microglia activation mediated neuronal necroptosis

Arsenic, an identified environmental toxicant, poses threats to the health of human beings through contaminated water and food. Recently, increasing reports focused on arsenic-induced nerve damage, however, the underlying mechanism remains elusive. Microglia are important immune cells in the nervous system, which produce a large number of inflammatory factors including TNF-α when activated. Recent reports indicated that TNF-α is involved in the process of necroptosis, a new type of programmed cell death discovered recently. Although there were evidences suggested that arsenic could induce both microglia activation and TNF-α production in the nervous system, the mechanism of arsenic-induced neurotoxicity due to microglia activation is rarely studied. In addition, the role of microglia-derived TNF-α in response to arsenic exposure in necroptosis has not been documented before. In this study, we found that arsenite induced microglial activation through p38 MAPK signaling pathway, leading to the production of TNF-α. Microglia-derived TNF-α further induced necroptosis in the neuronal cells. Our findings suggested that necroptosis induced by microglia-derived TNF-α upon arsenite exposure partially played a role in arsenic-induced cell death which underlie the fundamental event of arsenic-related neurotoxicity.

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.

A Novel Necroptosis-Related miRNA Signature for Predicting the Prognosis of Breast Cancer Metastasis

Objective

Necroptosis was recently identified as a form of programmed cell death that plays an essential role in breast cancer metastasis. MicroRNAs (miRNAs) have long been recognized to affect cell death and tumor growth. In this study, we aimed to screen for necroptosis-associated miRNAs that predict breast cancer metastasis.

Method

This study used The Cancer Genome Atlas (TCGA) public database to obtain miRNA expression data and associated clinical data from breast cancer patients and then retrieved miRNA data related to necrosis and apoptosis. Next, using Cox regression model analysis (univariate or multivariate) as well as a comparison analysis (differential analysis), a prognostic multi-miRNA molecular marker was established. Finally, prognosis-related miRNAs were utilized to identify target genes, and the functions of the target genes were analyzed for enrichment to investigate the probable mechanisms of the miRNAs.

Results

Ten miRNAs were screened through differential analysis to build models: hsa-miR-148a-3p, hsa-miR-223-3p, hsa-miR-331-3p, has-miR-181a-5p, hsa-miR-181b-5p, hsa-miR-181c-5p, hsa-miR-181d-5p, hsa-miR-200a-5p, hsa-miR-141-3p, and hsa-miR-425-5p. The multivariate Cox regression model was an independent prognostic factor (univariate Cox regression results: HR = 3.2642, 95%CI = 1.5773 − 6.7554, P = 0.0014; multivariate Cox regression results: HR = 3.1578, 95%CI = 1.5083 − 6, P = 0.0023). The survival curve of the risk score also revealed that patients with a high risk score had a poor prognosis (P = 2e − 04). The receiver operating characteristic (ROC) curve showed that the model has a certain prediction ability. Batch survival analysis of the miRNAs in the model was conducted and showed that hsa-miR-331-3p (P = 0.0182) was strongly associated with prognosis. Twenty-three predicted target genes were obtained, and Gene Ontology (GO) enrichment analysis showed that these target genes were strongly enriched in transcriptional initiation and cell membrane trafficking.

Conclusion

Our research identified a novel miRNA marker for predicting breast cancer patient prognosis and lays the groundwork for future research on necroptosis-related genes.

Role of Long Non-coding RNAs in the Pathogenesis of Alzheimer's and Parkinson's Diseases

Neurodegenerative diseases are a diverse group of diseases that are now one of the leading causes of morbidity in the elderly population. These diseases include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Amyotrophic Lateral Sclerosis (ALS), etc. Although these diseases have a common characteristic feature of progressive neuronal loss from various parts of the brain, they differ in the clinical symptoms and risk factors, leading to the development and progression of the diseases. AD is a neurological condition that leads to dementia and cognitive decline due to neuronal cell death in the brain, whereas PD is a movement disorder affecting neuro-motor function and develops due to the death of the dopaminergic neurons in the brain, resulting in decreased dopamine levels. Currently, the only treatment available for these neurodegenerative diseases involves reducing the rate of progression of neuronal loss. This necessitates the development of efficient early biomarkers and effective therapies for these diseases. Long non-coding RNAs (LncRNAs) belong to a large family of non-coding transcripts with a minimum length of 200 nucleotides. They are implied to be involved in the development of the brain, a variety of diseases, and epigenetic, transcriptional, and posttranscriptional levels of gene regulation. Aberrant expression of lncRNAs in the CNS is considered to play a major role in the development and progression of AD and PD, two of the most leading causes of morbidity among elderly populations. In this mini-review, we discuss the role of various long non-coding RNAs in neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, which can further be studied for the development of potential biomarkers and therapeutic targets for various neurodegenerative diseases.

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.

Mechanism of miR-132-3p Promoting Neuroinflammation and Dopaminergic Neurodegeneration in Parkinson's Disease

The major pathology in Parkinson’s disease (PD) is neuron injury induced by degeneration of dopaminergic neurons and the activation of microglial cells. The objective of this study is to determine the effect and mechanism of miR-132-3p in regulating neuroinflammation and the degeneration of dopaminergic neuron in PD. The expressions of miR-132-3p in brain tissues of PD patients, lipopolysaccharide (LPS)-induced BV-2 cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse models were detected. The effect of miR-132-3p and GLRX in cell viability, apoptosis and inflammation was verified in BV-2 cells. The activation of Iba1 in substantia nigra pars compacta (SNc) and the loss of tyrosine hydroxylase were detected in PD mouse models and the mobility of mouse models was assessed as well. The targeting relationship between miR-132-3p and GLRX was confirmed by RNA immunoprecipitation (RIP) and dual luciferase reporter gene assay. Elevated expression of miR-132-3p and decreased expression of GLRX were found in PD patients and cells models. Overexpression of miR-132-3p can induce activation of microglial cells, which can be reversed by GLRX overexpression. Collected evidence in both cell model and mouse models showed the effect of miR-132-3p in enhancing the activation of microglial cells and the loss of microglia cells, which was achieved by mediating GLRX.

MiR-4763-3p targeting RASD2as a Potential Biomarker and Therapeutic Target for Schizophrenia

Existing diagnostic methods are limited to observing appearance and demeanor, even though genetic factors play important roles in the pathology of schizophrenia. Indeed, no molecular-level test exists to assist diagnosis, which has limited treatment strategies. To address this serious shortcoming, we used a bioinformatics approach to identify 61 genes that are differentially expressed in schizophrenia patients compared with healthy controls. In particular, competing endogenous RNA network revealed the important role of the gene RASD2, which is regulated by miR-4763-3p. Indeed, analysis of blood samples confirmed that RASD2 is downregulated in schizophrenia patients. Moreover, positron emission tomography data collected for 44 human samples identified the prefrontal and temporal lobes as potential key brain regions in schizophrenia patients. Mechanistic studies indicated that miR-4763-3p inhibits RASD2 by base-pairing with the 3’ untranslated region of RASD2 mRNA. Importantly, RASD2 has been shown to interact with β-arrestin2, which contributes to the regulation of the DRD2-dependent CREB response element-binding protein pathway in the dopamine system. Finally, results obtained with a mouse model of schizophrenia revealed that inhibition of miR-4763-3p function alleviated anxiety symptoms and improved memory. The dopamine transporters in the striatal regions were significantly reduced in schizophrenia model mice as compared with wild-type mice, suggesting that inhibition of miR-4763-3p can lessen the symptoms of schizophrenia. Our findings demonstrate that miR-4763-3p may target RASD2 mRNA and thus may serve as a potential biomarker and therapeutic target for schizophrenia, providing a theoretical foundation for further studies of the molecular basis of this disease.

Regulated cell death: discovery, features and implications for neurodegenerative diseases

Regulated cell death (RCD) is a ubiquitous process in living organisms that is essential for tissue homeostasis or to restore biological balance under stress. Over the decades, various forms of RCD have been reported and are increasingly being found to involve in human pathologies and clinical outcomes. We focus on five high-profile forms of RCD, including apoptosis, pyroptosis, autophagy-dependent cell death, necroptosis and ferroptosis. Cumulative evidence supports that not only they have different features and various pathways, but also there are extensive cross-talks between modes of cell death. As the understanding of RCD pathway in evolution, development, physiology and disease continues to improve. Here we review an updated classification of RCD on the discovery and features of processes. The prominent focus will be placed on key mechanisms of RCD and its critical role in neurodegenerative disease. Video abstract.

Defining (and blocking) neuronal death in Parkinson's disease: Does it matter what we call it?

Parkinson's disease (PD) is the second most common neurodegenerative disease, comprised of both familial and idiopathic forms, behind only Alzheimer's disease (AD). The disease is characterized, regardless of the pathogenesis, primarily by a loss of DA neurons in the ventral midbrain as well as noradrenergic neurons of the locus coeruleus; however, by the time symptoms manifest, considerable neuronal loss in both areas has occurred. Neuroprotective strategies thus have to be paired with more sensitive and specific biomarker assays that can identify early at-risk patients in order to initiate disease-modifying therapies at an earlier stage in the disease. Complicating this is the fact that multiple forms of cell death mediate the neuronal loss; however, with a common underlying element that the cell death is considered a "regulated" form of cell death, in contrast to an un-controlled necrotic cell death process. In this review we focus our discussion on several categories of regulated cell death in the context of PD: apoptosis, necroptosis, pyroptosis, and autophagic cell death. In clinical studies as well as experimental in vivo models of PD, there is evidence for a role of each of these forms of cell death in the loss of midbrain DA neurons, and specific therapeutic strategies have been proposed and tested. What remains unclear however is the relative contributions of these distinct forms of cell death to the overall loss of DA neurons, whether they occur at different stages of the disease, or whether specific sub-regions within the midbrain are more susceptible to specific death triggers and pathways.

Parkinson's disease and microRNAs - Lessons from model organisms and human studies

Parkinson's disease (PD) is a progressive, age-associated neurodegenerative disorder that affects an estimated 10 million people worldwide. PD is characterized by proteinaceous, cytoplasmic inclusions containing α-synuclein, called Lewy Bodies, which form in dopaminergic neurons in an age-dependent manner, and are associated with the emergence of characteristic PD symptoms such as resting tremor, rigidity, slow movements and postural instability. Although considerable progress has been made in recent years in identifying genetic and environmental factors that are associated with PD, early diagnosis and therapeutic options remain severely lacking. Recently, microRNAs (miRNAs) have emerged as novel therapeutic targets in various diseases, such as cancer and neurodegenerative diseases. MiRNAs have been shown to play roles in various aging and neurodegenerative disease models across phyla. More recently, studies have identified specific roles for miRNAs and their targets in the pathogenesis and progression of PD in several model organisms. Here, we discuss the evolving field of miRNAs, their association with PD, and the outlook for the future.

MicroRNAs as Potential Orchestrators of Alzheimer's Disease-Related Pathologies: Insights on Current Status and Future Possibilities

Alzheimer's disease (AD) is a progressive and deleterious neurodegenerative disease, strongly affecting the cognitive functions and memory of seniors worldwide. Around 58% of the affected patients live in low and middle-income countries, with estimates of increasing deaths caused by AD in the coming decade. AD is a multifactor pathology. Mitochondrial function declines in AD brain and is currently emerging as a hallmark of this disease. It has been considered as one of the intracellular processes severely compromised in AD. Many mitochondrial parameters decline already during aging; mitochondrial efficiency for energy production, reactive oxygen species (ROS) metabolism and the de novo synthesis of pyrimidines, to reach an extensive functional failure, concomitant with the onset of neurodegenerative conditions. Besides its impact on cognitive functions, AD is characterized by loss of synapses, extracellular amyloid plaques composed of the amyloid-β peptide (Aβ), and intracellular aggregates of hyperphosphorylated Tau protein, accompanied by drastic sleep disorders, sensory function alterations and pain sensitization. Unfortunately, till date, effective management of AD-related disorders and early, non-invasive AD diagnostic markers are yet to be found. MicroRNAs (miRNAs) are small non-coding nucleic acids that regulate key signaling pathway(s) in various disease conditions. About 70% of experimentally detectable miRNAs are expressed in the brain where they regulate neurite outgrowth, dendritic spine morphology, and synaptic plasticity. Increasing studies suggest that miRNAs are intimately involved in synaptic function and specific signals during memory formation. This has been the pivotal key for considering miRNAs crucial molecules to be studied in AD. MicroRNAs dysfunctions are increasingly acknowledged as a pivotal contributor in AD via deregulating genes involved in AD pathogenesis. Moreover, miRNAs have been proved to control pain sensitization processes and regulate circadian clock system that affects the sleep process. Interestingly, the differential expression of miRNA panels implies their emerging potential as diagnostic AD biomarkers. In this review, we will present an updated analysis of miRNAs role in regulating signaling processes that are involved in AD-related pathologies. We will discuss the current challenges against wider use of miRNAs and the future promising capabilities of miRNAs as diagnostic and therapeutic means for better management of AD.

A Review of miRNAs as Biomarkers and Effect of Dietary Modulation in Obesity Associated Cognitive Decline and Neurodegenerative Disorders

There has been a progressive increase in the prevalence of obesity and its comorbidities such as type 2 diabetes and cardiovascular diseases worldwide. Recent studies have suggested that the crosstalk between adipose tissue and central nervous system (CNS), through cellular mediators and signaling pathways, may causally link obesity with cognitive decline and give rise to neurodegenerative disorders. Several mechanisms have been proposed in obesity, including inflammation, oxidative stress, insulin resistance, altered lipid and cholesterol homeostasis, which may result in neuroinflammation, altered brain insulin signaling, amyloid-beta (Aβ) deposition and neuronal cell death. Since obesity is associated with functional and morphological alterations in the adipose tissues, the resulting peripheral immune response augments the development and progression of cognitive decline and increases susceptibility of neurodegenerative disorders, such as Alzheimer's Disease (AD) and Parkinson's Disease (PD). Studies have also elucidated an important role of high fat diet in the exacerbation of these clinical conditions. However, the underlying factors that propel and sustain this obesity associated cognitive decline and neurodegeneration, remains highly elusive. Moreover, the mechanisms linking these phenomena are not well-understood. The cumulative line of evidence have demonstrated an important role of microRNAs (miRNAs), a class of small non-coding RNAs that regulate gene expression and transcriptional changes, as biomarkers of pathophysiological conditions. Despite the lack of utility in current clinical practices, miRNAs have been shown to be highly specific and sensitive to the clinical condition being studied. Based on these observations, this review aims to assess the role of several miRNAs and aim to elucidate underlying mechanisms that link obesity with cognitive decline and neurodegenerative disorders. Furthermore, this review will also provide evidence for the effect of dietary modulation which can potentially ameliorate cognitive decline and neurodegenerative diseases associated with obesity.

Selenium-deficient diet induces necroptosis in the pig brain by activating TNFR1 via mir-29a-3p

Selenium (Se) deficiency is one of the crucial factors related to nervous system disease and necroptosis. MicroRNAs (miRNAs) play vital roles in regulating necroptosis. However, the mechanism of Se deficiency-induced necroptosis in the pig brain tissue and the role that miRNAs play in this process are unclear. Therefore, in this study, in vitro and pig models of Se deficiency were replicated, and electron microscopy, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assays were performed. The results showed that brain cells typically undergo necrotic changes, and that Se deficiency suppresses mir-29a-3p, which increases the levels of TNFRSF1A (TNFR1). Subsequently, a distinct increase in the necroptosis markers (RIPK1, RIPK3, and MLKL) and an evident decrease in caspase 8 was observed. And the expression of 10 selenoproteins was decreased. Moreover, the in vitro experiments showed that the expression of mir-29a-3p decreased as the Se content in the medium decreased and the application of an mir-29a-3p inhibitor increased the number of necrotic cells and the accumulation of ROS, and these effects were inhibited by necrostatin-1 (Nec-1) and N-acetyl-cysteine (NAC), respectively. Taken together, we proved that Se deficiency induced necroptosis both in vitro and in vivo through the targeted regulation of TNFR1 by mir-29a-3p in the pig brain.

Non-coding RNAs in necroptosis, pyroptosis and ferroptosis in cancer metastasis

Distant metastasis is the main cause of death for cancer patients. Recently, the newly discovered programmed cell death includes necroptosis, pyroptosis, and ferroptosis, which possesses an important role in the process of tumor metastasis. At the same time, it is widely reported that non-coding RNA precisely regulates programmed death and tumor metastasis. In the present review, we summarize the function and role of necroptosis, pyrolysis, and ferroptosis involving in cancer metastasis, as well as the regulatory factors, including non-coding RNAs, of necroptosis, pyroptosis, and ferroptosis in the process of tumor metastasis.

Downregulation of long noncoding RNA SNHG7 protects against inflammation and apoptosis in Parkinson's disease model by targeting the miR-425-5p/TRAF5/NF-κB axis

Accumulated evidence has manifested that long noncoding RNA (lncRNA) is involved in the progress of Parkinson's disease (PD). SNHG7, a novel lncRNA, has been found to be involved in tumorigenesis. However, SNHG7 expression and its functional effects on PD remain uncharted. Rotenone (Rot) was adopted to construct PD models in Sprague-Dawley (SD) rats and SH-SY5Y cells, respectively. The expression levels of caspase 3, tyrosine hydroxylase (TH), ionized calcium-binding adapter molecule 1 (Iba1) in SD rat striatum were measured via immunohistochemistry and western blot. Additionally, the expressions of inflammatory cytokines (interleukin 1β [IL-1β], IL-6, tumor necrosis factor α) and oxidative stress factors (malondialdehyde, superoxide dismutase, and glutathione peroxidase) in the brain tissues were examined using real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Moreover, the protein levels of tumor necrosis factor receptor-associated factor (TRAF5), I-κB, nuclear factor-κB (NF-κB), HO-1, Nrf2 were detected via western blot. Bioinformatics was applied to predict the targeting relationship between SNHG7, miR-425-5p, and TRAF5. Dual-luciferase activity assay and RNA immunoprecipitation assays were conducted to verify their interactions. In comparison to healthy donors, SNHG7 was found upregulated while miR-425-5p expression was downregulated in PD patients. Functional experiments confirmed that SNHG7 downregulation or miR-425-5p overexpression attenuated neuronal apoptosis in the Rot-mediated PD model, TH-positive cell loss, and microglial activation by mitigating inflammation and oxidative stress. Mechanistically, SNHG7 served as a competitive endogenous RNA by sponging miR-425-5p and promoted TRAF5 mediated inflammation and oxidative stress. Inhibition of SNHG7 ameliorated neuronal apoptosis in PD through relieving miR-425-5p/TRAF5/NF-κB signaling pathway modulated inflammation and oxidative stress, and similar results were observed in the Rot-mediated rat model of PD.