MicroRNA-24-3p regulates neuronal differentiation by controlling hippocalcin expression

Novel miRNAs, miR-937-3p, miR-4536-3p, and miR-4650-5p, can Modulate Neuronal Differentiation via the Wnt/MAPK Pathway in SH-SY5Y Cells

MicroRNAs (miRNAs) are small non-coding RNAs that regulate various biological processes, including cell differentiation. Despite their potential, their role in promoting neuronal differentiation by targeting neuronal genes and modulating signaling pathways is poorly understood. In this study, we aimed to elucidate the functions of miR-937-3p-, miR-4536-3p-, and miR-4650-5p-inhibitors in the neuronal differentiation of SH-SY5Y cells. We also aimed to determine the underlying mechanisms via qPCR, luciferase assay, immunocytochemistry, and western blotting analysis. Our findings confirmed that miRNAs participated in neuronal differentiation and regulated the Wnt/MAPK signaling pathway. Specifically, we identified Netrin1 (NTN1), Drebrin1 (DBN1), and Netrin-G1 (NTNG1) as target genes of miR-937-3p, miR-4536-3p, and miR-4650-5p, respectively. The treatment with the miRNA inhibitors increased the expression levels of neuronal markers such as TUBB3, NEFH, NEFM, NEFL, and MAP2. It also enhanced the protein expression levels of Wnt and MAPK signaling. Therefore, the inhibitors of miR-937-3p, miR-4536-3p, and miR-4650-5p could promote neuronal differentiation by targeting neuronal genes and activating the Wnt/MAPK signaling pathway.

Differentiated and mature neurons are more responsive to neurotoxicant exposure at both transcriptional and translational levels

SH-SY5Y human neuroblastoma cells have been extensively used as an in vitro model system in a diverse range of studies involving neurodevelopment, neurotoxicity, neurodegeneration, and neuronal ageing. Both naïve and differentiated phenotypes of SH-SY5Y cells are utilized to model human neurons under in vitro conditions. The process of differentiation causes extensive remodeling of neuronal cells at multiple omic levels, including the epigenome and proteome. In the present investigation, the miRNAome and proteome profiles of arsenic-treated naïve and differentiated SH-SY5Y cells were generated using the miRNA OpenArray technology and high-resolution mass spectrometry. Our findings demonstrated that differentiation dramatically affected the response of SH-SY5Y cells to toxicant exposure, as indicated by increased tolerance of differentiated cells against arsenic exposure compared to naïve cells in cell viability assay. Arsenic-exposed naïve and differentiated SH-SY5Y cells possess distinct miRNA and protein profiles with few similarities. Compared to naïve cells, differentiated cells have undergone higher deregulation in the expression of brain-enriched miRNAs and proteins and have shown a more drastic decrease in oxygen consumption rate, which is a measure of mitochondrial respiration after exposure to arsenic. Proteins identified in arsenic-treated differentiated SH-SY5Y cells were more enriched in pathways underlying multifactorial neurotoxic events. Additionally, more functional regulatory modules have been identified between the miRNAs and proteins differentially expressed in arsenic-treated differentiated SH-SY5Y cells relative to naïve cells. Collectively, our studies have shown that differentiated SH-SY5Y cells displayed alterations in the expression of a greater number of miRNAs and proteins following neurotoxicant exposure, indicating their higher responsivity.

The expression profile of brain-derived exosomal miRNAs reveals the key molecules responsible for spontaneous motor function recovery in a rat model with permanent middle cerebral artery occlusion

The analysis of alterations in the expression and functionality of brain-derived exosomal miRNAs within ischemic stroke lesions provides significant insights into the mechanisms that contribute to disease recovery. We assessed spontaneous motor function in a rat model of permanent middle cerebral artery occlusion (pMCAO) using motor function scores and magnetic resonance imaging (MRI). Brain-derived exosomes from the infarcted brain tissue of the animal model were extracted and high-throughput sequencing of them was performed followed by bioinformatics analysis for differentially expressed miRNAs target genes. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to measure expression levels of differentially expressed miRNAs at various time points. The oxygen-glucose deprivation (OGD) model was established to investigate gene function through the assessment of cell proliferation and apoptosis using EdU proliferation and JC-1 apoptosis assay. The rat model demonstrated a spontaneous recovery of motor function and a reduction in cerebral infarction area from day 1 to day 14 post-operation. Over the course of the recovery period, miR-24-3p, miR-129-1-3p, and miR-212-5p maintained consistent expression levels, reaching their peak on the initial day following surgery. In the cell model, EdU detection indicated that miR-129-1-3p promoted cellular proliferation, while JC-1 detection revealed its suppressive impact on cellular apoptosis. The current research findings indicated the presence of spontaneous motor function restoration in a rat model of ischemic stroke. MiR-24-3p, miR-129-1-3p, and miR-212-5p were identified as pivotal genes in this recovery process, with miR-129-1-3p potentially influencing the restoration of spontaneous motor function in ischemic stroke through the regulation of neuronal proliferation and apoptosis.

MFGE8 promotes adult hippocampal neurogenesis in rats following experimental subarachnoid hemorrhage via modifying the integrin β3/Akt signaling pathway

Subarachnoid hemorrhage (SAH) is one of the most severe type of cerebral strokes, which can cause multiple cellular changes in the brain leading to neuronal injury and neurological deficits. Specifically, SAH can impair adult neurogenesis in the hippocampal dentate gyrus, thus may affecting poststroke neurological and cognitive recovery. Here, we identified a non-canonical role of milk fat globule epidermal growth factor 8 (MFGE8) in rat brain after experimental SAH, involving a stimulation on adult hippocampal neurogenesis(AHN). Experimental SAH was induced in Sprague-Dawley rats via endovascular perforation, with the in vivo effect of MFGE8 evaluated via the application of recombinant human MFGE8 (rhMFGE8) along with pharmacological interventions, as determined by hemorrhagic grading, neurobehavioral test, and histological and biochemical analyses of neurogenesis related markers. Results: Levels of the endogenous hippocampal MFGE8 protein, integrin-β3 and protein kinase B (p-Akt) were elevated in the SAH relative to control groups, while that of hippocalcin (HPCA) and cyclin D1 showed the opposite change. Intraventricular rhMGFE8 infusion reversed the decrease in doublecortin (DCX) immature neurons in the DG after SAH, along with improved the short/long term neurobehavioral scores. rhMGFE8 treatment elevated the levels of phosphatidylinositol 3-kinase (PI3K), p-Akt, mammalian target of rapamycin (mTOR), CyclinD1, HPCA and DCX in hippocampal lysates, but not that of integrin β3 and Akt, at 24 hr after SAH. Treatment of integrin β3 siRNA, the PI3K selective inhibitor ly294002 or Akt selective inhibitor MK2206 abolished the effects of rhMGFE8 after SAH. In conclusion, MFGE8 is upregulated in the hippocampus in adult rats with reduced granule cell genesis. rhMFGE8 administration can rescue this impaired adult neurogenesis and improve neurobehavioral recovery. Mechanistically, the effect of MFGE8 on hippocampal adult neurogenesis is mediated by the activation of integrin β3/Akt pathway. These findings suggest that exogenous MFGE8 may be of potential therapeutic value in SAH management. Graphical abstract and proposed pathway of rhMFGE8 administration attenuate hippocampal injury by improving neurogenesis in SAH models. SAH caused hippocampal injury and neurogenesis interruption. Administered exogenous MFGE8, recombinant human MFGE8(rhMFGE8), could ameliorate hippocampal injury and improve neurological functions after SAH. Mechanistically, MFGE8 bind to the receptor integrin β3, which activated the PI3K/Akt pathway to increase the mTOR expression, and further promote the expression of cyclin D1, HPCA and DCX. rhMFGE8 could attenuated hippocampal injury by improving neurogenesis after SAH, however, know down integrin β3 or pharmacological inhibited PI3K/Akt by ly294002 or MK2206 reversed the neuro-protective effect of rhMFGE8.

Decoding single-cell molecular mechanisms in astrocyte-to-iN reprogramming via Ngn2- and Pax6-mediated direct lineage switching

BACKGROUND

The limited regenerative capacity of damaged neurons in adult mammals severely restricts neural repair. Although stem cell transplantation is promising, its clinical application remains challenging. Direct reprogramming, which utilizes cell plasticity to regenerate neurons, is an emerging alternative approach.

METHODS

We utilized primary postnatal cortical astrocytes for reprogramming induced neurons (iNs) through the viral-mediated overexpression of the transcription factors Ngn2 and Pax6 (NP). Fluorescence-activated cell sorting (FACS) was used to enrich successfully transfected cells, followed by single-cell RNA sequencing (scRNA-seq) using the 10 × Genomics platform for comprehensive transcriptomic analysis.

RESULTS

The scRNA-seq revealed that NP overexpression led to the differentiation of astrocytes into iNs, with percentages of 36% and 39.3% on days 4 and 7 posttransduction, respectively. CytoTRACE predicted the developmental sequence, identifying astrocytes as the reprogramming starting point. Trajectory analysis depicted the dynamic changes in gene expression during the astrocyte-to-iN transition.

CONCLUSIONS

This study elucidates the molecular dynamics underlying astrocyte reprogramming into iNs, revealing key genes and pathways involved in this process. Our research contributes novel insights into the molecular mechanisms of NP-mediated reprogramming, suggesting avenues for optimizing the efficiency of the reprogramming process.

Essential metals modified the effects of polycyclic aromatic hydrocarbons on the metabolic syndrome: Mediation effects of miRNA

Metabolic syndrome (MetS) prevalence has increased dramatically worldwide and has become a public health issue. Polycyclic aromatic hydrocarbons (PAHs) were identified as risk factors of MetS, while essential metals are integral parts of metalloenzymes catalyzing metabolic processes. However, effects of co-exposure to PAHs and essential metals have not been investigated yet. We aimed to assess whether essential metals could modify the hazard effects of PAHs on MetS, and underlying mediation effects of microRNA (miRNAs) were further explored. A cross-sectional study of 1451 males including 278 MetS cases was conducted. Internal exposure levels of 5 classes of PAH metabolites, 7 essential metals, as well as expressions of PAHs-associated 8 plasma miRNAs were assessed. Multiple exposure models, Bayesian kernel machine regression (BKMR), and quantile g-computation (QGcomp) were used simultaneously to identify MetS-related critical chemicals. Mutual effect modification between chemicals and mediation effects of miRNAs on chemical-MetS association was testified. In this study, hydroxyphenanthrene (OHPhe) and selenium (Se) were consistently identified as MetS-related key chemicals in three statistical methods. OHPhe was positively associated with MetS [OR (95 % CI) = 1.79 (1.21, 2.65), P = 0.004], while Se had a negative relationship with MetS [OR (95 % CI) = 0.61 (0.43, 0.87), P = 0.007]. Effect modification analysis observed the association between OHPhe and MetS was weakened with increased Se exposure. Only the expression of miR-24-3p was negatively associated with MetS [OR (95 % CI) = 0.81 (0.66, 0.95), P = 0.048] and could mediate 16.1 % of OHPhe-MetS association in subjects with low Se exposure (≤0.87 μg/mmol creatinine) (P = 0.019). We found a mutual effect modification between OHPhe and Se on MetS, and the positive OHPhe-MetS association was attenuated with increased Se exposure. Mediation effects of miR-24-3p on OHPhe-MetS association were dependent on Se dose. Our findings may provide new insight into the prevention and intervention of MetS.

Mesenchymal Stem Cell-Extracellular Vesicle Therapy for Stroke: Scalable Production and Imaging Biomarker Studies

A major clinical hurdle to translate MSC-derived extracellular vesicles (EVs) is the lack of a method to scale-up the production of EVs with customized therapeutic properties. In this study, we tested whether EV production by a scalable 3D-bioprocessing method is feasible and improves neuroplasticity in animal models of stroke using MRI study. MSCs were cultured in a 3D-spheroid using a micro-patterned well. The EVs were isolated with filter and tangential flow filtration and characterized using electron microscopy, nanoparticle tracking analysis, and small RNA sequencing. Compared to conventional 2D culture, the production-reproduction of EVs (the number/size of particles and EV purity) obtained from 3D platform were more consistent among different lots from the same donor and among different donors. Several microRNAs with molecular functions associated with neurogenesis were upregulated in EVs obtained from 3D platform. EVs induced both neurogenesis and neuritogenesis via microRNAs (especially, miR-27a-3p and miR-132-3p)-mediated actions. EV therapy improved functional recovery on behavioral tests and reduced infarct volume on MRI in stroke models. The dose of MSC-EVs of 1/30 cell dose had similar therapeutic effects. In addition, the EV group had better anatomical and functional connectivity on diffusion tensor imaging and resting-state functional MRI in a mouse stroke model. This study shows that clinical-scale MSC-EV therapeutics are feasible, cost-effective, and improve functional recovery following experimental stroke, with a likely contribution from enhanced neurogenesis and neuroplasticity.

MiR-24-3p/Dio3 axis is essential for BDE47 to induce local thyroid hormone disorder and neurotoxicity

BDE47 (2,2,4,4-tetrabromodiphenyl ether) is a member of the most important congeners of polybrominated diphenyl ethers (PBDEs) and has been identified as a developmental, reproductive and nervous system toxicant and endocrine system disruptor due to its frequent detection in human tissue and environmental samples. Our preliminary work suggested that high- and low-level of bromodiphenyl ethers have different effects on neuronal cells with differential targets of actions on neural tissues. In this study, we presented the underlying mechanism of BDE47 neurotoxicity from the perspective of thyroid hormone (TH) metabolism using in vitro model of human SK-N-AS neuronal cells. BDE47 could induce local TH metabolism disorder in neuronal cells by inhibiting the expression of the main enzyme, human type III iodothyronine deiodinase (Dio3). Further elucidation revealed that BDE47 effectively up-regulating miR-24-3p, which binds to the 3'-UTR of Dio3 and inhibits its expression. In addition, BDE47 could also inhibit the deiodinase activity of Dio3. Collectively, our study demonstrates the molecular mechanism of BDE47 regulating Dio3-induced TH metabolism disorder through inducing miR-24-3p, providing new clues for the role of miRNAs in neurodevelopmental toxicity mediated by environmental pollutants.

FUS Alters circRNA Metabolism in Human Motor Neurons Carrying the ALS-Linked P525L Mutation

Deregulation of RNA metabolism has emerged as one of the key events leading to the degeneration of motor neurons (MNs) in Amyotrophic Lateral Sclerosis (ALS) disease. Indeed, mutations on RNA-binding proteins (RBPs) or on proteins involved in aspects of RNA metabolism account for the majority of familiar forms of ALS. In particular, the impact of the ALS-linked mutations of the RBP FUS on many aspects of RNA-related processes has been vastly investigated. FUS plays a pivotal role in splicing regulation and its mutations severely alter the exon composition of transcripts coding for proteins involved in neurogenesis, axon guidance, and synaptic activity. In this study, by using in vitro-derived human MNs, we investigate the effect of the P525L FUS mutation on non-canonical splicing events that leads to the formation of circular RNAs (circRNAs). We observed altered levels of circRNAs in FUS^P525L MNs and a preferential binding of the mutant protein to introns flanking downregulated circRNAs and containing inverted Alu repeats. For a subset of circRNAs, FUS^P525L also impacts their nuclear/cytoplasmic partitioning, confirming its involvement in different processes of RNA metabolism. Finally, we assess the potential of cytoplasmic circRNAs to act as miRNA sponges, with possible implications in ALS pathogenesis.

Circ-Vps41 positively modulates Syp and its overexpression improves memory ability in aging mice

INTRODUCTION

Age is an established risk factor for neurodegenerative disorders. Aging-related cognitive decline is a common cause of memory impairment in aging individuals, in which hippocampal synaptic plasticity and hippocampus-dependent memory formation are damaged. Circular RNAs (circRNAs) have been reported in many cognitive disorders, but their role in aging-related memory impairment is unclear.Methods: In this study, we aimed to investigate the effects of circ-Vps41 on aging-related hippocampus-dependent memory impairment and explore the potential mechanisms. Here, D-galactose was used to produce a conventional aging model resulting in memory dysfunction.

RESULTS

Circ-Vps41 was significantly downregulated in D-galactose-induced aging in vitro and in vivo. The overexpression of circ-Vps41 could upregulate synaptophysin (Syp), thereby promoting the synaptic plasticity and alleviating cognitive impairment in aging mice. Mechanistically, we found that circ-Vps41 upregulated Syp expression by physically binding to miR-24-3p. Moreover, the miR-24-3p mimics reversed the circ-Vps41 overexpression-induced increase in Syp expression.

DISCUSSION

Overexpression of circ-Vps41 alleviated the synaptic plasticity and memory dysfunction via the miR-24-3p/Syp axis. These findings revealed circ-Vps41 regulatory network and provided new insights into its potential mechanisms for improving aging-related learning and memory impairment.

Dynamin-Independent Mechanisms of Endocytosis and Receptor Trafficking

Endocytosis is a fundamental mechanism by which cells perform housekeeping functions. It occurs via a variety of mechanisms and involves many regulatory proteins. The GTPase dynamin acts as a “molecular scissor” to form endocytic vesicles and is a critical regulator among the proteins involved in endocytosis. Some GTPases (e.g., Cdc42, arf6, RhoA), membrane proteins (e.g., flotillins, tetraspanins), and secondary messengers (e.g., calcium) mediate dynamin-independent endocytosis. These pathways may be convergent, as multiple pathways exist in a single cell. However, what determines the specific path of endocytosis is complex and challenging to comprehend. This review summarizes the mechanisms of dynamin-independent endocytosis, the involvement of microRNAs, and factors that contribute to the cellular decision about the specific route of endocytosis.

Xenogenic Neural Stem Cell-Derived Extracellular Nanovesicles Modulate Human Mesenchymal Stem Cell Fate and Reconstruct Metabolomic Structure

Extracellular nanovesicles, particularly exosomes, can deliver their diverse bioactive biomolecular content, including miRNAs, proteins, and lipids, thus providing a context for investigating the capability of exosomes to induce stem cells toward lineage-specific cells and tissue regeneration. In this study, it is demonstrated that rat subventricular zone neural stem cell-derived exosomes (rSVZ-NSCExo) can control neural-lineage specification of human mesenchymal stem cells (hMSCs). Microarray analysis shows that the miRNA content of rSVZ-NSCExo is a faithful representation of rSVZ tissue. Through immunocytochemistry, gene expression, and multi-omics analyses, the capability to use rSVZ-NSCExo to induce hMSCs into a neuroglial or neural stem cell phenotype and genotype in a temporal and dose-dependent manner via multiple signaling pathways is demonstrated. The current study presents a new and innovative strategy to modulate hMSCs fate by harnessing the molecular content of exosomes, thus suggesting future opportunities for rSVZ-NSCExo in nerve tissue regeneration.

Immunomodulatory Properties of Human Breast Milk: MicroRNA Contents and Potential Epigenetic Effects

Infants who are exclusively breastfed in the first six months of age receive adequate nutrients, achieving optimal immune protection and growth. In addition to the known nutritional components of human breast milk (HBM), i.e., water, carbohydrates, fats and proteins, it is also a rich source of microRNAs, which impact epigenetic mechanisms. This comprehensive work presents an up-to-date overview of the immunomodulatory constituents of HBM, highlighting its content of circulating microRNAs. The epigenetic effects of HBM are discussed, especially those regulated by miRNAs. HBM contains more than 1400 microRNAs. The majority of these microRNAs originate from the lactating gland and are based on the remodeling of cells in the gland during breastfeeding. These miRNAs can affect epigenetic patterns by several mechanisms, including DNA methylation, histone modifications and RNA regulation, which could ultimately result in alterations in gene expressions. Therefore, the unique microRNA profile of HBM, including exosomal microRNAs, is implicated in the regulation of the genes responsible for a variety of immunological and physiological functions, such as FTO, INS, IGF1, NRF2, GLUT1 and FOXP3 genes. Hence, studying the HBM miRNA composition is important for improving the nutritional approaches for pregnancy and infant's early life and preventing diseases that could occur in the future. Interestingly, the composition of miRNAs in HBM is affected by multiple factors, including diet, environmental and genetic factors.

MiR-24-3p Attenuates Doxorubicin-induced Cardiotoxicity via the Nrf2 Pathway in Mice

OBJECTIVE

The nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) is associated with doxorubicin (DOX)-induced cardiac injury. It has been reported that microRNA-24-3p (miR-24-3p) may regulate the Keapl by mRNA degradation, whereas Keapl can suppress the activation of Nrf2. However, the role of miR-24-3p in DOX-related cardiotoxicity remains unclear.

METHODS

The mice receiving DOX were used as cardiac injury model. In this study, an adenoassociated virus 9 system was used to deliver miR-24-3p or miR-scramble to mice hearts. The echocardiographic and hemodynamic analyses were used to evaluate the effects of miR-24-3p on cardiac function under DOX stimulation. ELISA and RT-PCR were used to detect protein or mRNA expressions associated with cardiac injury, inflammation response, apoptosis and oxidative stress. Western Blot were used for quantitative analysis of the roles of miR-24-3p in regulating Nrf2 expression. H9C2 cells used to verify the role of miR-24-3p in vitro.

RESULTS

We found that miR-24-3p mRNA was significantly decreased in DOX-treated mice and cardiomyocytes. Overexpression of miR-24-3p blocked cardiac injury caused by DOX injection, as reflected by the reduction in the levels of cardiac troponin I, creatinine kinase isoenzyme MB and the N-terminal pro brain natriuretic peptide. Furthermore, miR-24-3p reduced oxidative stress and cell loss without affecting the inflammation response. As expected, we found that Nrf2 was upregulated by miR-24-3p supplementation, and that the protective efforts of miR-24-3p supplementation were abolished when Nrf2 was silenced.

CONCLUSION

The results from this study suggest that miR-24-3p protects cardiomyocytes against DOX-induced heart injury via activation of the Nrf2 pathway. miR-24-3p supplementation may be a novel strategy to counteract the cardiac side effects of DOX treatment.

Versatile role of miR-24/24-1*/24-2* expression in cancer and other human diseases

MiRNAs (miRs) have been proven to be well-validated therapeutic targets. Emerging evidence has demonstrated that intricate, intrinsic and paradoxical functions of miRs are context-dependent because of their multiple upstream regulators, broad spectrum of downstream molecular targets and distinct expression in various tissues, organs and disease states. Targeted therapy has become an emerging field of research. One key for the development of successful miR-based/targeted therapy is to acquire integrated knowledge of its regulatory network and its association with disease phenotypes to identify critical nodes of the underlying pathogenesis. Herein, we systematically summarized the comprehensive role of miR-24-3p (miR-24), along with its passenger strands miR-24-1-5p* (miR-24-1) and miR-24-2-5p* (miR-24-2), emphasizing their microenvironment, intracellular targets, and associated gene networks and regulatory phenotypes in 18 different cancer types and 13 types of other disorders. MiR-24 targets and regulates numerous genes in various cancer types and enhances the expression of several oncogenes (e.g., cMyc, BCL2 and HIF1), which are challenging in terms of druggability. In contrast, several tumor suppressor proteins (p21 and p53) have been reported to be downregulated by miR-24. MiR-24 also regulates the cell cycle and is associated with numerous cancer hallmarks such as apoptosis, proliferation, metastasis, invasion, angiogenesis, autophagy, drug resistance and other diseases pathogenesis. Overall, miR-24 plays an emerging role in the diagnosis, prognosis and pathobiology of various diseases. MiR-24 is a potential target for targeted therapy in the era of precision medicine, which expands the landscape of targetable macromolecules, including undruggable proteins.

miR-223-3p and miR-24-3p as novel serum-based biomarkers for myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is the most common adult-onset muscular dystrophy, primarily characterized by muscle wasting and weakness. Many biomarkers already exist in the rapidly developing biomarker research field that aim to improve patients' care. Limited work, however, has been performed on rare diseases, including DM1. We have previously shown that specific microRNAs (miRNAs) can be used as potential biomarkers for DM1 progression. In this report, we aimed to identify novel serum-based biomarkers for DM1 through high-throughput next-generation sequencing. A number of miRNAs were identified that are able to distinguish DM1 patients from healthy individuals. Two miRNAs were selected, and their association with the disease was validated in a larger panel of patients. Further investigation of miR-223-3p, miR-24-3p, and the four previously identified miRNAs, miR-1-3p, miR-133a-3p, miR-133b-3p, and miR-206-3p, showed elevated levels in a DM1 mouse model for all six miRNAs circulating in the serum compared to healthy controls. Importantly, the levels of miR-223-3p, but not the other five miRNAs, were found to be significantly downregulated in five skeletal muscles and heart tissues of DM1 mice compared to controls. This result provides significant evidence for its involvement in disease manifestation.

Serum aberrant expression of miR-24-3p and its diagnostic value in Alzheimer's disease

Aim: This study aimed to evaluate the effect of miR-24-3p in Alzheimer's disease (AD). Materials & methods: A total of 198 participants were recruited in this study, including 104 AD patients and 94 healthy controls. Expression of miR-24-3p was detected using quantitative real-time PCR. Receiver-operating characteristic curve was used to assess the diagnostic value of miR-24-3p. In vitro AD model was established to evaluate the effect of miR-24-3p. The downstream target was detected by luciferase reporter gene assay. Results: Expression of miR-24-3p showed 1.6-fold increase in AD group compared with healthy controls, and a negative correlation of miR-24-3p with mini-mental state examination score was obtained. Receiver-operating characteristic curve showed satisfactory diagnostic accuracy. Downregulation of miR-24-3p promoted cell proliferation and inhibited cell apoptosis. KLF8 is a target gene of miR-24-3p. Conclusion: MiR-24-3p has a certain value in the diagnosis of AD and may be a potential biomarker.

Herpes simplex virus 1 evades cellular antiviral response by inducing microRNA-24, which attenuates STING synthesis

STING is a nodal point for cellular innate immune response to microbial infections, autoimmunity and cancer; it triggers the synthesis of the antiviral proteins, type I interferons. Many DNA viruses, including Herpes Simplex Virus 1 (HSV1), trigger STING signaling causing inhibition of virus replication. Here, we report that HSV1 evades this antiviral immune response by inducing a cellular microRNA, miR-24, which binds to the 3’ untranslated region of STING mRNA and inhibits its translation. Expression of the gene encoding miR-24 is induced by the transcription factor AP1 and activated by MAP kinases in HSV1-infected cells. Introduction of exogenous miR-24 or prior activation of MAPKs, causes further enhancement of HSV1 replication in STING-expressing cells. Conversely, transfection of antimiR-24 inhibits virus replication in those cells. HSV1 infection of mice causes neuropathy and death; using two routes of infection, we demonstrated that intracranial injection of antimiR-24 alleviates both morbidity and mortality of the infected mice. Our studies reveal a new immune evasion strategy adopted by HSV1 through the regulation of STING and demonstrates that it can be exploited to enhance STING’s antiviral action.

The type I interferon system is the first line of cellular antiviral innate immune response. Virus infection is recognized by various pattern recognition receptors in the infected cell and it activates the interferon system to inhibit virus replication. However, viruses have evolved various mechanisms to evade the cellular immune response and enhance viral replication. Our study uncovers an immune evasion strategy used by the Herpes Simplex virus to circumvent the cGAS/STING signaling pathway which is the pivotal innate immune response to combat DNA virus replication. miR-24 induction by HSV1 targets STING and hence, dampens Type I Immune response against the virus. The induction of miR-24 is regulated by virus induced MAPK activation, which are also required during early lytic cycles of HSV1 replication and is indispensable for HSV1 reactivation from latency in neurons; depicting a new direct co-relation between MAPK activation and HSV1 replication orchestrated through cellular miR-24. Silencing of miR-24 in mice brain curtails viral replication and disease severity. Overall, these results indicate possible therapeutic use of stable antimiR-24 against HSV1 and other diseases that are alleviated by STING.

CircRtn4 Acts as the Sponge of miR-24-3p to Promote Neurite Growth by Regulating CHD5

Circular RNAs (circRNAs) are covalently closed single-stranded RNA molecules. After derived from precursor mRNA back-splicing, circRNAs play important roles in many biological processes. Recently, it was shown that several circRNAs were enriched in the mammalian brain with unclear functions. The expression of circRtn4 in the mouse brain was increased with the differentiation of primary neurons. In our study, knockdown of circRtn4 inhibited neurite growth, while overexpression of circRtn4 significantly increased neurite length. By dual-luciferase reporter assay and RNA antisense purification assay, circRtn4 was identified as a miRNA sponge for miR-24-3p. Moreover, knockdown of miR-24-3p increased neurite length, while overexpression of miR-24-3p significantly inhibited neurite growth. Furthermore, CHD5 was confirmed to be a downstream target gene of miR-24-3p. And CHD5 silence counteracted the positive effect of circRtn4 overexpression on neurite growth. In conclusion, circRtn4 may act as the sponge for miR-24-3p to promote neurite growth by regulating CHD5.

ErbB4 mediates amyloid β-induced neurotoxicity through JNK/tau pathway activation: Implications for Alzheimer's disease

Accumulation of amyloid β (Aβ) in the brain is a hallmark of Alzheimer's disease (AD). We previously showed that ErbB4 in parvalbumin (PV)-positive interneurons was associated with Aβ-induced cognitive deficits; however, the underlying mechanism remains undetermined. Here we found that specific deletion of ErbB4 in PV neurons significantly attenuated oligomeric Aβ-induced neuronal toxicity and inhibited Aβ-induced decreases of PSD95 and synaptophysin. Moreover, specific ablation of ErbB4 in PV neurons altered activity-related protein c-Fos and decreased hippocampal PV neurons, especially in the dentate gyrus (DG) of hAPP-J20 mice. Furthermore, c-Jun N-terminal kinase (JNK), a protein downstream of ErbB4, was activated by Aβ but not ErbB4's ligand neuregulin 1 (NRG1) β1, suggesting different downstream pathways for Aβ and NRG1β1. JNK phosphorylation was inhibited by the ErbB4 inhibitor AG1478 and by pretreatment with NRG1β1. More importantly, siRNA knockdown of ErbB4 decreased JNK phosphorylation and expression, tau phosphorylation at Ser396 and Thr 205, and Bax expression. Therefore, ErbB4 might mediate Aβ-induced neuropathology through the JNK/tau pathway and represent a potential therapeutic target in patients with AD.