Synaptic plasticity and depression: the role of miRNAs dysregulation

Serum exosomal hsa-miR-142-5p, hsa-miR-1908-5p, and hsa-miR-450b-5p as candidate biomarkers for recurrent depressive disorder diagnosis and ECT treatment response: A preliminary investigation

PURPOSE

This study investigated the differential expression of serum exosomal miRNAs in female patients with recurrent depressive disorder (RDD) before and after non-convulsive electroconvulsive therapy (ECT), aiming to explore potential diagnostic and therapeutic biomarkers.

METHOD

Serum samples were collected from three groups: healthy female volunteers aged 30-50, female patients with RDD prior to ECT, and female patients post-ECT who had achieved remission. Exosomes were isolated from serum, identified through transmission electron microscopy, nanoparticle tracking analysis, and Western blot analysis of exosomal markers. Total RNA was extracted from exosomes, and miRNA sequencing was conducted to identify differentially expressed miRNAs. Gene target prediction, Gene Ontology, and KEGG pathway enrichment analyses were also performed.

RESULTS

miRNA sequencing revealed significant differences in exosomal miRNA profiles among the three groups. Compared to controls, 69 miRNAs were upregulated and 98 downregulated in the model group, while the recovery group showed 41 upregulated and 51 downregulated miRNAs compared to the model group. Furthermore, the recovery group exhibited 35 upregulated and 59 downregulated miRNAs compared to controls. Analysis identified hsa-miR-142-5p, hsa-miR-1908-5p, and hsa-miR-450b-5p as potential biomarkers for RDD diagnosis and ECT treatment response, with functional roles likely related to inflammation, neurotransmission, and synaptic plasticity.

CONCLUSION

Serum exosomal miRNAs, particularly hsa-miR-142-5p, hsa-miR-1908-5p, and hsa-miR-450b-5p, emerged as promising candidates for further investigation as biomarkers for RDD diagnosis and treatment monitoring. Larger, multi-center studies are warranted to validate these findings.

Targeted miRNA Delivery in Epilepsy: Mechanisms, Advances, and Therapeutic Potential

Epilepsy, a neurological disorder characterized by recurrent seizures, presents significant therapeutic challenges, with roughly 30% of individuals demonstrating resistance to antiepileptic drugs. Drug-resistant epilepsy diminishes patients' quality of life and underscores the critical need for innovative therapeutic approaches. MicroRNAs, small non-coding RNA molecules, have emerged as key regulators in the pathogenesis of epilepsy, influencing neuronal excitability, synaptic plasticity, and neuroinflammatory processes. By targeting multiple genes and pathways involved in epileptogenesis, miRNAs offer promising opportunities for precision medicine. This review explores the dual roles of specific miRNAs in epilepsy, acting as both promoters and inhibitors of pathogenic pathways, and highlights recent advancements in miRNA-based therapeutic delivery systems. State-of-the-art approaches, including lipid nanoparticles, viral vectors, and exosome-based systems, are being developed to address challenges such as blood-brain barrier penetration, targeted delivery, and minimizing systemic side effects. These advancements lay the groundwork for more effective and personalized treatment strategies.

MicroRNA signatures in neuroplasticity, neuroinflammation and neurotransmission in association with depression

Depression is a multifactorial disorder that occurs mainly on account of the dysregulation of neuroplasticity, neurotransmission and neuroinflammation in the brain. In addition to environmental /lifestyle factors, the pathogenesis of disease has been associated with genetic and epigenetic factors that affect the reprogramming of normal brain function. MicroRNA (miRNAs), a type of non-coding RNAs, are emerging as significant players that play a vital role in the regulation of gene expression and have been extensively explored in neurodegenerative disorders. Recent studies have also shown the role of gut microbiota that forms a complex bidirectional network with gut brain axis, impacting neuroinflammation in case of Parkinson's disease and depression. Translating targeted miRNA-based therapies for the treatment of neurological disorders including depression, into clinical practice remains challenging due to the ineffective delivery of the therapeutic molecules and off-target effects of the specific miRNAs. This review provides significant insights into how miRNAs are emerging as vital players in the development of depression, especially the ones involved in three important processes including neuroplasticity, neurotransmission and neuroinflammation. In this review, the current status of miRNAs as biomarkers for therapeutic interventions in the case of depression has been discussed along with an overview of future perspectives, like use of nanotechnology and gene editing, keeping in view other multifactorial disorders where such interventions by mimics and inhibitors have already reached clinical trials. The challenges for targeting the specific miRNAs for therapeutic outcomes have also been highlighted.

MicroRNA-specific targets for neuronal plasticity, neurotransmitters, neurotrophic factors, and gut microbes in the pathogenesis and therapeutics of depression

Depression is of great concern because of the huge burden, and it is impacted by various epigenetic modifications, e.g., histone modification, covalent modifications in DNA, and silencing mechanisms of non-coding protein genes, e.g., microRNAs (miRNAs). MiRNAs are a class of endogenous non-coding RNAs. Alternations in specific miRNAs have been observed both in depressive patients and experimental animals. Also, miRNAs are highly expressed in the central nervous system and can be delivered to different tissues via tissue-specific exosomes. However, the mechanism of miRNAs' involvement in the pathological process of depression is not well understood. Therefore, we summarized and discussed the role of miRNAs in depression. Conclusively, miRNAs are involved in the pathology of depression by causing structural and functional changes in synapses, mediating neuronal regeneration, differentiation, and apoptosis, regulating the gut microbes and the expression of various neurotransmitters and BDNF, and mediating inflammatory and immune responses. Moreover, miRNAs can predict the efficacy of antidepressant medications and explain the mechanism of action of antidepressant drugs and aerobic exercise to prevent and assist in treating depression.

Circ-Bptf Ameliorates Learning and Memory Impairments via the miR-138-5p/p62 Axis in APP/PS1 Mice

Alzheimer's disease (AD) is a common age-associated progressive neurodegenerative disorder that is implicated in the aberrant regulation of numerous circular RNAs (circRNAs). Here, we reported that circ-Bptf, a conserved circRNA derived from the Bptf gene, showed an age-dependent decrease in the hippocampus of APP/PS1 mice. Overexpression of circ-Bptf significantly reversed dendritic spine loss and learning and memory impairment in APP/PS1 mice. Moreover, we found that circ-Bptf was predominantly localized to the cytoplasm and upregulated p62 expression by binding to miR-138-5p. Furthermore, the miR-138-5p mimics reversed the decreased expression of p62 induced by the silencing of circ-Bptf. Together, our findings suggested that circ-Bptf ameliorated learning and memory impairments via the miR-138-5p/p62 axis in APP/PS1 mice. It may act as a potential player in AD pathogenesis and therapy.

CRISPR-Cas13a-Triggered DNAzyme Signal Amplification-Based Colorimetric miRNA Detection Method and Its Application in Evaluating the Anxiety

The development of a bio-sensing strategy based on CRISPR/Cas that is exceptionally sensitive is crucial for the identification of trace molecules. Colorimetric miRNA detection utilizing CRISPR/Cas13a-triggered DNAzyme signal amplification was described in this article. The developed strategy was implemented for miRNA-21 detection as a proof of concept. The cleavage activity of Cas13a was triggered when the target molecule bonded to the Cas13a-crRNA complex and cleaved uracil ribonucleotides (rU) in the substrate probe. As a consequence, the S chain was liberated from the T chain that had been modified on magnetic beads (MB). The G-rich sections were then exposed when the catalytic hairpin assembly between the H1 and H2 probes was activated by the released T@MB. G-rich section can fold into G-quadruplex. By catalyzing the formation of green ABTS3- via HRP-mimicking G-quadruplex/hemin complexes, colorimetric measurements of miRNA can be achieved visually through DNAzyme-mediated signal amplification. The method demonstrated a low limit of detection of 27 fM and a high selectivity towards target miRNA eventually. As a result, the developed strategy provides a clinical application platform for the detection of miRNAs that is both ultrasensitive and extremely specific.

Deciphering the role of miRNA-134 in the pathophysiology of depression: A comprehensive review

This study summarizes the significance of microRNA-134 (miRNA-134) in the pathophysiology, diagnosis, and treatment of depression, a disease still under investigation due to its complexity. miRNA-134 is an endogenous short non-coding RNA that can bind to the 3' untranslated region (3'UTR) of miRNA-134, inhibiting gene translation and showing great potential in the regulation of mood, synaptic plasticity, and neuronal function. This study included 15 articles retrieved from four English-language databases: PubMed, Embase, The Cochrane Library, and Web of Science, and three Chinese literature databases: CNKI, Wanfang, and Chinese Science and Technology Periodical Database (VIP).We evaluated each of the 15 articles using the Critical Appraisal Skills Program (CASP) tool.The standard integrates analyzes of genomic, transcriptomic, neuroimaging, and behavioral data analyses related to miRNA-134 and depression. A multidimensional framework based on standardized criteria was used for quality assessment. The main findings indicate that miRNA-134 significantly affects synaptic plasticity and neurotransmitter regulation, in particular the synthesis and release of serotonin and dopamine. miRNA-134 shows high sensitivity and specificity as a biomarker for the diagnosis of depression and has therapeutic potential for the targeted treatment of depression. miRNA-134 plays a crucial role in the pathogenesis of depression, providing valuable insights for early diagnosis and the development of targeted therapeutic strategies. This work highlights the potential of miRNA-134 as a focal point for advancing personalized medicine approaches for depression.

Deciphering Depression: Epigenetic Mechanisms and Treatment Strategies

Depression, a significant mental health disorder, is under intense research scrutiny to uncover its molecular foundations. Epigenetics, which focuses on controlling gene expression without altering DNA sequences, offers promising avenues for innovative treatment. This review explores the pivotal role of epigenetics in depression, emphasizing two key aspects: (I) identifying epigenetic targets for new antidepressants and (II) using personalized medicine based on distinct epigenetic profiles, highlighting potential epigenetic focal points such as DNA methylation, histone structure alterations, and non-coding RNA molecules such as miRNAs. Variations in DNA methylation in individuals with depression provide opportunities to target genes that are associated with neuroplasticity and synaptic activity. Aberrant histone acetylation may indicate that antidepressant strategies involve enzyme modifications. Modulating miRNA levels can reshape depression-linked gene expression. The second section discusses personalized medicine based on epigenetic profiles. Analyzing these patterns could identify biomarkers associated with treatment response and susceptibility to depression, facilitating tailored treatments and proactive mental health care. Addressing ethical concerns regarding epigenetic information, such as privacy and stigmatization, is crucial in understanding the biological basis of depression. Therefore, researchers must consider these issues when examining the role of epigenetics in mental health disorders. The importance of epigenetics in depression is a critical aspect of modern medical research. These findings hold great potential for novel antidepressant medications and personalized treatments, which would significantly improve patient outcomes, and transform psychiatry. As research progresses, it is expected to uncover more complex aspects of epigenetic processes associated with depression, enhance our comprehension, and increase the effectiveness of therapies.

Temporal changes in mouse hippocampus transcriptome after pilocarpine-induced seizures

Introduction

Status epilepticus (SE) is a seizure lasting more than 5 min that can have lethal consequences or lead to various neurological disorders, including epilepsy. Using a pilocarpine-induced SE model in mice we investigated temporal changes in the hippocampal transcriptome.

Methods

We performed mRNA-seq and microRNA-seq analyses at various times after drug treatment.

Results

At 1 h after the start of seizures, hippocampal cells upregulated transcription of immediate early genes and genes involved in the IGF-1, ERK/MAPK and RNA-PolII/transcription pathways. At 8 h, we observed changes in the expression of genes associated with oxidative stress, overall transcription downregulation, particularly for genes related to mitochondrial structure and function, initiation of a stress response through regulation of ribosome and translation/EIF2 signaling, and upregulation of an inflammatory response. During the middle of the latent period, 36 h, we identified upregulation of membrane components, cholesterol synthesis enzymes, channels, and extracellular matrix (ECM), as well as an increased inflammatory response. At the end of the latent period, 120 h, most changes in expression were in genes involved in ion transport, membrane channels, and synapses. Notably, we also elucidated the involvement of novel pathways, such as cholesterol biosynthesis pathways, iron/BMP/ferroptosis pathways, and circadian rhythms signaling in SE and epileptogenesis.

Discussion

These temporal changes in metabolic reactions indicate an immediate response to injury followed by recovery and regeneration. CREB was identified as the main upstream regulator. Overall, our data provide new insights into molecular functions and cellular processes involved at different stages of seizures and offer potential avenues for effective therapeutic strategies.

Role of Apolipoprotein E in the Hippocampus and Its Impact following Ionizing Radiation Exposure

Apolipoprotein E (ApoE) is a lipid carrier in both the peripheral and the central nervous systems (CNSs). Lipid-loaded ApoE lipoprotein particles bind to several cell surface receptors to support membrane homeostasis and brain injury repair. In the brain, ApoE is produced predominantly by astrocytes, but it is also abundantly expressed in most neurons of the CNS. In this study, we addressed the role of ApoE in the hippocampus in mice, focusing on its role in response to radiation injury. To this aim, 8-week-old, wild-type, and ApoE-deficient (ApoE-/-) female mice were acutely whole-body irradiated with 3 Gy of X-rays (0.89 Gy/min), then sacrificed 150 days post-irradiation. In addition, age-matching ApoE-/- females were chronically whole-body irradiated (20 mGy/d, cumulative dose of 3 Gy) for 150 days at the low dose-rate facility at the Institute of Environmental Sciences (IES), Rokkasho, Japan. To seek for ApoE-dependent modification during lineage progression from neural stem cells to neurons, we have evaluated the cellular composition of the dentate gyrus in unexposed and irradiated mice using stage-specific markers of adult neurogenesis. Our findings indicate that ApoE genetic inactivation markedly perturbs adult hippocampal neurogenesis in unexposed and irradiated mice. The effect of ApoE inactivation on the expression of a panel of miRNAs with an established role in hippocampal neurogenesis, as well as its transcriptional consequences in their target genes regulating neurogenic program, have also been analyzed. Our data show that the absence of ApoE-/- also influences synaptic functionality and integration by interfering with the regulation of mir-34a, mir-29b, and mir-128b, leading to the downregulation of synaptic markers PSD95 and synaptophysin mRNA. Finally, compared to acute irradiation, chronic exposure of ApoE null mice yields fewer consequences except for the increased microglia-mediated neuroinflammation. Exploring the function of ApoE in the hippocampus could have implications for developing therapeutic approaches to alleviate radiation-induced brain injury.

AFM Imaging Reveals MicroRNA-132 to be a Positive Regulator of Synaptic Functions

The modification of synaptic and neural connections in adults, including the formation and removal of synapses, depends on activity-dependent synaptic and structural plasticity. MicroRNAs (miRNAs) play crucial roles in regulating these changes by targeting specific genes and regulating their expression. The fact that somatic and dendritic activity in neurons often occurs asynchronously highlights the need for spatial and dynamic regulation of protein synthesis in specific milieu and cellular loci. MicroRNAs, which can show distinct patterns of enrichment, help to establish the localized distribution of plasticity-related proteins. The recent study using atomic force microscopy (AFM)-based nanoscale imaging reveals that the abundance of miRNA(miR)-134 is inversely correlated with the functional activity of dendritic spine structures. However, the miRNAs that are selectively upregulated in potentiated synapses, and which can thereby support prospective changes in synaptic efficacy, remain largely unknown. Using AFM force imaging, significant increases in miR-132 in the dendritic regions abutting functionally-active spines is discovered. This study provides evidence for miR-132 as a novel positive miRNA regulator residing in dendritic shafts, and also suggests that activity-dependent miRNAs localized in distinct sub-compartments of neurons play bi-directional roles in controlling synaptic transmission and synaptic plasticity.

Neural Mechanisms of Nonauditory Effects of Noise Exposure on Special Populations

Due to the abnormal structure and function of brain neural networks in special populations, such as children, elderly individuals, and individuals with mental disorders, noise exposure is more likely to have negative psychological and cognitive nonauditory effects on these individuals. There are unique and complex neural mechanisms underlying this phenomenon. For individuals with mental disorders, there are anomalies such as structural atrophy and decreased functional activation in brain regions involved in emotion and cognitive processing, such as the prefrontal cortex (PFC). Noise exposure can worsen these abnormalities in relevant brain regions, further damaging neural plasticity and disrupting normal connections and the transmission of information between the PFC and other brain areas by causing neurotransmitter imbalances. In the case of children, in a noisy environment, brain regions such as the left inferior frontal gyrus and PFC, which are involved in growth and development, are more susceptible to structural and functional changes, leading to neurodegenerative alterations. Furthermore, noise exposure can interrupt auditory processing neural pathways or impair inhibitory functions, thus hindering children's ability to map sound to meaning in neural processes. For elderly people, age-related shrinkage of brain regions such as the PFC, as well as deficiencies in hormone, neurotransmitter, and nutrient levels, weakens their ability to cope with noise. Currently, it is feasible to propose and apply coping strategies to improve the nonauditory effects of noise exposure on special populations based on the plasticity of the human brain.

MiR-128-3p - a gray eminence of the human central nervous system

MicroRNA-128-3p (miR-128-3p) is a versatile molecule with multiple functions in the physiopathology of the human central nervous system. Perturbations of miR-128-3p, which is enriched in the brain, contribute to a plethora of neurodegenerative disorders, brain injuries, and malignancies, as this miRNA is a crucial regulator of gene expression in the brain, playing an essential role in the maintenance and function of cells stemming from neuronal lineage. However, the differential expression of miR-128-3p in pathologies underscores the importance of the balance between its high and low levels. Significantly, numerous reports pointed to miR-128-3p as one of the most depleted in glioblastoma, implying it is a critical player in the disease's pathogenesis and thus may serve as a therapeutic agent for this most aggressive form of brain tumor. In this review, we summarize the current knowledge of the diverse roles of miR-128-3p. We focus on its involvement in the neurogenesis and pathophysiology of malignant and neurodegenerative diseases. We also highlight the promising potential of miR-128-3p as an antitumor agent for the future therapy of human cancers, including glioblastoma, and as the linchpin of brain development and function, potentially leading to the development of new therapies for neurological conditions.

NLRP3/miR-223-3p axis attenuates neuroinflammation induced by chronic intermittent hypoxia

Obstructive sleep apnea (OSA) is mainly characterized by chronic intermittent hypoxia (CIH) with multiple brain injuries. Nucleotide oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is considered the most important factor inducing and maintaining inflammation. However, the role of NLRP3 and its underlying mechanism in CIH-elicited neuroinflammation remains unclear. We constructed an OSA-related CIH in vivo model and assessed the rats' cognitive behavior in the Morris water maze. The combination of miR-223-3p and NLRP3 was confirmed by the TargetScan database, double luciferase reporter gene experiment, and RNA immunoprecipitation (RIP) experiment. Western blot and ELISA assay were used to analyze the effects of miR-223-3p targeting NLRP3 on the expression of pyroptotic or inflammatory factors in vivo in CIH rats. Severe cognitive impairment was observed in rats at week 6 post-treatment, with increased inflammatory factors in the blood and hippocampus, heightened NLRP3 expression, and low miR-223-3p levels. And the good binding activity of the two was confirmed by dual luciferase reporter and RIP experiments. Next, we found that silencing NLRP3 or overexpression of miR-223-3p in the CIH model could improve cognitive deficits and reduce the level of proinflammatory factors and pyroptosis factors in rats. Finally, based on silencing NLRP3 or overexpression miR-223-3p, we confirmed that there was a regulatory relationship between miR-223-3p and NLRP3. Our results suggested that the NLRP3/ miR-223-3p axis played a role in attenuating CIH-induced neuroinflammation.

Hemispheric asymmetries in mental disorders: evidence from rodent studies

The brain is built with hemispheric asymmetries in structure and function to enable fast neuronal processing. In neuroimaging studies, several mental disorders have been associated with altered or attenuated hemispheric asymmetries. However, the exact mechanism linking asymmetries and disorders is not known. Here, studies in animal models of mental disorders render important insights into the etiology and neuronal alterations associated with both disorders and atypical asymmetry. In this review, the current literature of animal studies in rats and mice focusing on anxiety and fear, anhedonia and despair, addiction or substance misuse, neurodegenerative disorders as well as stress exposure, and atypical hemispheric asymmetries is summarized. Results indicate overall increased right-hemispheric neuronal activity and a left-sided behavioral bias associated with symptoms of anxiety, fear, anhedonia, behavioral despair as well as stress exposure. Addiction behavior is associated with right-sided bias and transgenic models of Alzheimer's disease indicate an asymmetrical accumulation of fibrillar plaques. Most studies focused on changes in the bilateral amygdala and frontal cortex. Across studies, two crucial factors influencing atypical asymmetries arose independently of the disorder modeled: sex and developmental age. In conclusion, animal models of mental disorders demonstrate atypical hemispheric asymmetries similar to findings in patients. Particularly, increased left-sided behavior and greater right-hemispheric activity were found across models applying stress-based paradigms. However, sex- and age-dependent effects on atypical hemispheric asymmetries are present that require further investigation. Animal models enable the analysis of hemispheric changes on the molecular level which may be most effective to detect early alterations.

Role of miR-219a-5p in regulating NMDAR in nonylphenol-induced synaptic plasticity damage

Nonylphenol (NP) is a typical environmental endocrine disruptor with estrogenic effects. It serves as an emulsifier and as the main ingredient of detergents and has become an increasingly common pollutant in both fresh and salt water, vegetables, and fruits. This study aimed to clarify whether NP exposure could lead to cognitive dysfunction and synaptic plasticity impairment, and also explore the mechanism of microRNA (miR)- 219a-5p regulation of N-methyl-D-aspartate receptor (NMDAR) in NP-induced synaptic plasticity impairment in vivo and in vitro. In vivo, 30 male Sprague-Dawley rats were randomly divided into 2 groups: blank control group (pure corn oil) and NP-exposed group [NP 80 mg/(kg·d)], with 15 rats in each group. In vitro, the extracted hippocampal neurons were divided into 6 groups: blank control group, mimics NC group, miR-219 mimics group, NP group (70 μmol/L NP), NP + mimics NC group, and NP + miR-219 mimics group. In vivo, the content of NP in hippocampal tissues after 90 days of NP exposure was significantly higher in the NP-stained group than in the blank control group. NP exposure could lead to a decrease in the ability to learn and memory, ability to remember, and space spatial memory ability in rats. The dendrites in the NP-stained group were disordered, with few dendritic spines and significantly decreased dendritic spine density. The postsynaptic densities were loosely arranged, the thickness and length of the postsynaptic densities shortened, and the length and width of the synaptic gap increased. Glutamine (Glu) and γ-aminobutyric acid (GABA) contents in hippocampal tissues decreased in the NP-stained group. The expression of miR-219a-5p mRNA decreased in the NP-stained group after 3 months of NP exposure. The expression of NMDAR1, NMDAR2A, NMDAR2B, nerve growth-associated protein (GAP-43), and Ca/calmodulin-dependent kinase II (CaMKII) mRNA/proteins decreased in the NP-stained group. In vitro, NMDAR protein expression decreased, while GAP-43 and CaMKII protein expression increased in the miR-219 mimics group compared with the control group. The expression levels of NMDAR and GAP-43 and CaMKII proteins were higher in the NP + miR-219 mimics group compared with the NP group. The levels of neurotransmitters Glu and GABA decreased in the NP and NP + mimics NC groups compared with the blank group. Shortened synaptic active band length, decreased thickness of postsynaptic densities, and shortened length of postsynaptic densities were observed in the NP, NP + mimics NC, and NP + miR-219 mimics groups compared with the blank control group. In vivo, NP exposure reduced learning memory capacity and neurotransmitter content in rats and caused a decrease in dendritic spine density and synaptic number density and a decrease in miR-219a-5p expression. In vitro, high expression of miR-219a-5p inhibited the expression of NMDAR, thus reducing the effect of NP on synaptic plasticity impairment in hippocampal neurons. Our study provided a scientific basis for the prevention of cognitive impairment owing to NP exposure and the development of targeted drug treatment strategies.

circRNA from APP Gene Changes in Alzheimer's Disease Human Brain

Alzheimer's disease (AD) is the most common cause of age-related dementia. Amyloid precursor protein (APP) is the precursor of Aβ peptides, and its role in AD has been widely investigated. Recently, it has been reported that a circular RNA (circRNA) originated from APP gene can serve as a template for Aβ synthesis, postulating it as an alternative pathway for the Aβ biogenesis. Moreover, circRNAs play important roles in brain development and in neurological diseases. Therefore, our aim was to study the expression of a circAPP (hsa_circ_0007556) and its linear cognate in AD human entorhinal cortex, a brain region most vulnerable to AD pathology. First, we confirmed the presence of circAPP (hsa_circ_0007556) in human entorhinal cortex samples using RT-PCR and Sanger sequencing of PCR products. Next, a 0.49-fold decrease in circAPP (hsa_circ_0007556) levels was observed in entorhinal cortex of AD cases compared to controls (p-value < 0.05) by qPCR. In contrast, APP mRNA expression did not show changes in the entorhinal cortex between AD cases and controls (Fold-change = 1.06; p-value = 0.81). A negative correlation was found between Aβ deposits and circAPP (hsa_circ_0007556) and APP expression levels (Rho Spearman = -0.56, p-value < 0.001 and Rho Spearman = -0.44, p-values < 0.001, respectively). Finally, by using bioinformatics tools, 17 miRNAs were predicted to bind circAPP (hsa_circ_0007556), and the functional analysis predicted that they were involved in some pathways, such as the Wnt-signaling pathway (p = 3.32 × 10^-6). Long-term potentiation (p = 2.86 × 10^-5), among others, is known to be altered in AD. To sum up, we show that circAPP (hsa_circ_0007556) is deregulated in the entorhinal cortex of AD patients. These results add to the notion that circAPP (hsa_circ_0007556) could be playing a role in the pathogenesis of AD disease.

Identification and characterization of noncoding RNAs-associated competing endogenous RNA networks in major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a common and serious mental illness. Many novel genes in MDD have been characterized by high-throughput methods such as microarrays or sequencing. Recently, noncoding RNAs (ncRNAs) were suggested to be involved in the complicated environmental-genetic regulatory network of MDD occurrence; however, the interplay among RNA species, including protein-coding RNAs and ncRNAs, in MDD remains unclear.

AIM

To investigate the RNA expression datasets downloaded from a public database and construct a network based on differentially expressed long noncoding RNA (lncRNAs), microRNAs (miRNAs), and mRNAs between MDD and controls.

METHODS

Gene expression data were searched in NCBI Gene Expression Omnibus using the search term “major depressive disorder.” Six array datasets from humans were related to the search term: GSE19738, GSE32280, GSE38206, GSE52790, GSE76826, and GSE81152. These datasets were processed for initial assessment and subjected to quality control and differential expression analysis. Differentially expressed lncRNAs, miRNAs, and mRNAs were determined, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed, and protein-protein interaction network was generated. The results were analyzed for their association with MDD.

RESULTS

After analysis, 3 miRNAs, 12 lncRNAs, and 33 mRNAs were identified in the competing endogenous RNA network. Two of these miRNAs were earlier shown to be involved in psychiatric disorders, and differentially expressed mRNAs were found to be highly enriched in pathways related to neurogenesis and neuroplasticity as per Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. The expression of hub gene fatty acid 2-hydroxylase was enriched, and the encoded protein was found to be involved in myelin formation, indicating that neurological development and signal transduction are involved in MDD pathogenesis.

CONCLUSION

The present study presents candidate ncRNAs involved in the neurogenesis and neuroplasticity pathways related to MDD.

Dissecting early life stress-induced adolescent depression through epigenomic approach

Early life stress (ELS), such as abuse and neglect during childhood, can lead to psychiatric disorders in later life. Previous studies have suggested that ELS can cause profound changes in gene expression through epigenetic mechanisms, which can lead to psychiatric disorders in adulthood; however, studies on epigenetic modifications associated with ELS and psychiatric disorders in adolescents are limited. Moreover, how these epigenetic modifications can lead to psychiatric disorders in adolescents is not fully understood. Commonly, DNA methylation, histone modification, and the regulation of noncoding RNAs have been attributed to the reprogramming of epigenetic profiling associated with ELS. Although only a few studies have attempted to examine epigenetic modifications in adolescents with ELS, existing evidence suggests that there are commonalities and differences in epigenetic profiling between adolescents and adults. In addition, epigenetic modifications are sex-dependent and are influenced by the type of ELS. In this review, we have critically evaluated the current evidence on epigenetic modifications in adolescents with ELS, particularly DNA methylation and the expression of microRNAs in both preclinical models and humans. We have also clarified the impact of ELS on psychiatric disorders in adolescents to predict the development of neuropsychiatric disorders and to prevent and recover these disorders through personalized medicine.