MicroRNA-20b-5p aggravates neuronal apoptosis induced by β-Amyloid via down-regulation of Ras homolog family member C in Alzheimer's disease

Regulation of Apoptotic Pathways by MicroRNAs: A Therapeutic Strategy for Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder marked by a gradual decline in memory and cognitive functions. It is characterized by the presence of senile plaques, neurofibrillary tangles, and neuronal degeneration, affecting a significant portion of the human population. A key feature of various nervous system disorders, including AD, is extensive cellular death caused by apoptosis, which affects not only neurons but also glial cells. While apoptosis plays a vital role in eliminating certain cells and supporting normal development, alterations or disruptions in apoptotic pathways can lead to harmful neurodegenerative conditions such as AD. Thus, targeting apoptosis presents a promising therapeutic approach for these diseases. MicroRNAs (miRNAs), a class of non-coding RNA, play diverse roles in cellular functions, including proliferation, gene expression regulation, programmed cell death, intercellular communication, and angiogenesis. By modulating regulatory genes, miRNAs can influence apoptosis, either promoting or inhibiting it. Aberrant expression of miRNAs can impact multiple apoptotic pathways, potentially driving the progression of AD and related health issues. This review summarizes recent research on miRNAs and their dual role in exacerbating or protecting against neural cell damage in AD by altering apoptotic pathways. The regulation of apoptosis by miRNAs offers a prospective therapeutic strategy for Alzheimer's disease.

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

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

NcRNAs: A synergistically antiapoptosis therapeutic tool in Alzheimer's disease

AIMS

The aim of this review is to systematically summarize and analyze the noncoding RNAs (ncRNAs), especially microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), in the cell apoptosis among Alzheimer's disease (AD) in recent years to demonstrate their value in the diagnosis and treatment of AD.

METHODS

We systematically summarized in vitro and in vivo studies focusing on the ncRNAs in the regulation of cell apoptosis among AD in PubMed, ScienceDirect, and Google Scholar.

RESULTS

We discover three patterns of ncRNAs (including 'miRNA-mRNA', 'lncRNA-miRNA-mRNA', and 'circRNA-miRNA-mRNA') form the ncRNA-based regulatory networks in regulating cell apoptosis in AD.

CONCLUSIONS

This review provides a future diagnosis and treatment strategy for AD patients based on ncRNAs.

Effects of a High-Fat Diet on Insulin-Related miRNAs in Plasma and Brain Tissue in APPSwe/PS1dE9 and Wild-Type C57BL/6J Mice

Insulin resistance (IR)-related miRNAs have been associated with the development and progression of Alzheimer's disease (AD). The dietary modulation of these miRNAs could become a potential strategy to manage AD. The aim of this study was to evaluate the effect of a high-fat diet (HFD), which aggravates AD-related pathogenic processes, on serum, cortex and hippocampus IR-related miRNA expression. C57BL/6J WT and APPSwe/PS1dE9 mice were fed either an HFD or a conventional diet till 6 months of age. The mice fed with the HFD showed a significant increase in body weight and worsening glucose and insulin metabolism. miR-19a-3p was found to be up-regulated in the cortex, hippocampus and serum of APP/PS1 mice and in the serum and hippocampus of WT mice fed with the HFD. miR-34a-5p and miR-146a-5p were up-regulated in the serum of both groups of mice after consuming the HFD. Serum miR-29c-3p was overexpressed after consuming the HFD, along with hippocampal miR-338-3p and miR-125b-5p, only in WT mice. The HFD modulated the expression of peripheral and brain miRNAs related to glucose and insulin metabolism, suggesting the potential role of these miRNAs not only as therapeutic targets of AD but also as peripheral biomarkers for monitoring AD.

Beyond CSF and Neuroimaging Assessment: Evaluating Plasma miR-145-5p as a Potential Biomarker for Mild Cognitive Impairment and Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia. New strategies for the early detection of MCI and sporadic AD are crucial for developing effective treatment options. Current techniques used for diagnosis of AD are invasive and/or expensive, so they are not suitable for population screening. Cerebrospinal fluid (CSF) biomarkers such as amyloid β1-42 (Aβ1-42), total tau (T-tau), and phosphorylated tau181 (P-tau181) levels are core biomarkers for early diagnosis of AD. Several studies have proposed the use of blood-circulating microRNAs (miRNAs) as potential novel early biomarkers for AD. We therefore applied a novel approach to identify blood-circulating miRNAs associated with CSF biomarkers and explored the potential of these miRNAs as biomarkers of AD. In total, 112 subjects consisting of 28 dementia due to AD cases, 63 MCI due to AD cases, and 21 cognitively healthy controls were included. We identified seven Aβ1-42-associated plasma miRNAs, six P-tau181-associated plasma miRNAs, and nine Aβ1-42-associated serum miRNAs. These miRNAs were involved in AD-relevant biological processes, such as PI3K/AKT signaling. Based on this signaling pathway, we constructed an miRNA-gene target network, wherein miR-145-5p has been identified as a hub. Furthermore, we showed that miR-145-5p performs best in the prediction of both AD and MCI. Moreover, miR-145-5p also improved the prediction performance of the mini-mental state examination (MMSE) score. The performance of this miRNA was validated using different datasets including an RT-qPCR dataset from plasma samples of 23 MCI cases and 30 age-matched controls. These findings indicate that blood-circulating miRNAs that are associated with CSF biomarkers levels and specifically plasma miR-145-5p alone or combined with the MMSE score can potentially be used as noninvasive biomarkers for AD or MCI screening in the general population, although studies in other AD cohorts are necessary for further validation.

Insights into role of microRNA in Alzheimer's disease: From contemporary research to bedside perspective

One of the most prevalent neurodegenerative disorders is Alzheimer's disease (AD). Despite the pervasiveness of AD being considerable, the rates of both diagnosis and therapy are comparatively less and still lacking. For the treatment of AD, acetylcholinesterase inhibitors and NMDA receptor antagonists (Memantine) have received clinical approval. The approved drugs are only capable of mitigating the symptoms; however, halting the progression of the disease remains a matter of substantial concern. MicroRNAs (miRs) are a subclass of non-coding single-stranded RNA molecules that target mRNAs to control the expression of genes in certain tissues. Dysregulation in the expression and function of miRs contributes to a neurodegeneration-like pathogenesis seen in Alzheimer's disease (AD), featuring hallmark characteristics such as Aβ aggregation, hyper-phosphorylation of Tau proteins, mitochondrial dysfunction, neuroinflammation, and apoptosis. These factors collectively underpin the cognitive deterioration and learning disabilities associated with AD. According to the research, numerous miRs have considerably different expression patterns in AD patients compared to healthy people. Due to these attributes, miRs prove to be effective diagnostic and therapeutic agents for AD. This review will examine clinical and preclinical data concerning the potential of miRs as diagnostic and therapeutic agents, utilizing various techniques (such as miR antagonists or inhibitors, miR agonists or mimics, miR sponges, and miR antisense oligonucleotides) to target specific pathogenic mechanisms in AD.

siRNA drug delivery across the blood-brain barrier in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with a few FDA-approved drugs that provide modest symptomatic benefits and only two FDA-approved disease-modifying treatments for AD. The advancements in understanding the causative genes and non-coding sequences at the molecular level of the pathophysiology of AD have resulted in several exciting research papers that employed small interfering RNA (siRNA)-based therapy. Although siRNA is being sought by academia and biopharma industries, several challenges still need to be addressed. We comprehensively report the latest advances in AD pathophysiology, druggable targets, ongoing clinical trials, and the siRNA-based approaches across the blood-brain barrier for addressing AD. This review describes the latest delivery systems employed to address this barrier. Critical insights and future perspectives on siRNA therapy for AD are also provided.

The Role of Caspases in Alzheimer's Disease: Pathophysiology Implications and Pharmacologic Modulation

Alzheimer's disease (AD) is the most common neurodegenerative disorder worldwide. Although the main cause of the onset and development of AD is not known yet, neuronal death due to pathologic changes such as amyloid-β (Aβ) deposition, tau aggregation, neuroinflammation, oxidative stress, and calcium dyshomeostasis are considered to be the main cause. At the present, there is no cure for this insidious disorder. However, accurate identification of molecular changes in AD can help provide new therapeutic goals. Caspases are a group of proteases which are known because of their role in cellular apoptosis. In addition, different caspases are involved in other cellular responses to the environment, such as induction of inflammation. Emerging evidence suggest that these proteases play a central role in AD pathophysiology due to their role in the processing of amyloid-β protein precursor, tau cleavage, and neuroinflammation. Therefore, it seems that targeting caspases may be a suitable therapeutic option to slow the progression of AD. This review focuses on the role of caspases in AD pathophysiology and introduce results from studies targeted caspases in different models of AD.

The emerging role of miR-20b in human cancer and other disorders: Pathophysiology and therapeutic implications

miR-20b is a microRNA with diverse and somehow contradictory roles in the pathogenesis of human disorders, especially cancers. It has been known to be a tumor suppressor in colon cancer, renal cell carcinoma, prostate cancer, osteosarcoma and papillary thyroid cancer. In lung cancer and breast cancers, both tumor suppressor and oncogenic effects have been identified for this miRNA. Finally, in T cell leukemia, hepatocellular carcinoma, esophageal squamous cell carcinoma and cervical and gastric cancers, miR-20b is regarded as an oncogenic miRNA. In several types of cancer, dysregulation of miR-20b has been recognized as a predictive marker for patients' survival. Dysregulation of miR-20b has also been recognized in Alzheimer's disease, diabetic retinopathy, myocardial ischemia/infarction, chronic hepatitis B and multiple sclerosis. In the current review, we have summarized the miR-20b targets and related cellular processes. We have also provided a review of participation of this miRNA in different human disorders.

The role of H3K9 acetylation and gene expression in different brain regions of Alzheimer's disease patients

Aims: To evaluate H3K9 acetylation and gene expression profiles in three brain regions of Alzheimer's disease (AD) patients and elderly controls, and to identify AD region-specific abnormalities. Methods: Brain samples of auditory cortex, hippocampus and cerebellum from AD patients and controls underwent chromatin immunoprecipitation sequencing, RNA sequencing and network analyses. Results: We found a hyperacetylation of AD cerebellum and a slight hypoacetylation of AD hippocampus. The transcriptome revealed differentially expressed genes in the hippocampus and auditory cortex. Network analysis revealed Rho GTPase-mediated mechanisms. Conclusions: These findings suggest that some crucial mechanisms, such as Rho GTPase activity and cytoskeletal organization, are differentially dysregulated in brain regions of AD patients at the epigenetic and transcriptomic levels, and might contribute toward future research on AD pathogenesis.

The Role of miR-20 in Health and Disease of the Central Nervous System

Current understanding of the mechanisms underlying central nervous system (CNS) injury is limited, and traditional therapeutic methods lack a molecular approach either to prevent acute phase or secondary damage, or to support restorative mechanisms in the nervous tissue. microRNAs (miRNAs) are endogenous, non-coding RNA molecules that have recently been discovered as fundamental and post-transcriptional regulators of gene expression. The capacity of microRNAs to regulate the cell state and function through post-transcriptionally silencing hundreds of genes are being acknowledged as an important factor in the pathophysiology of both acute and chronic CNS injuries. In this study, we have summarized the knowledge concerning the pathophysiology of several neurological disorders, and the role of most canonical miRNAs in their development. We have focused on the miR-20, the miR-17~92 family to which miR-20 belongs, and their function in the normal development and disease of the CNS.

Schizophrenia Risk Mediated by microRNA Target Genes Overlapped by Genome-Wide Rare Copy Number Variation in 22q11.2 Deletion Syndrome

The 22q11.2 deletion is associated with >20-fold increased risk for schizophrenia. The presence of gene DGCR8 in the 22q11.2 deletion region has suggested microRNA (miRNA) dysregulation as possibly contributing to this risk. We therefore investigated the role of miRNA target genes in the context of previously identified genome-wide risk for schizophrenia conveyed by additional copy number variation (CNV) in 22q11.2 deletion syndrome (22q11.2DS). Using a cohort of individuals with 22q11.2DS and documented additional rare CNVs overlapping protein coding genes, we compared those with schizophrenia (n = 100) to those with no psychotic illness (n = 118), assessing for rare CNVs that overlapped experimentally supported miRNA target genes. We further characterized the contributing miRNA target genes using gene set enrichment analyses and identified the miRNAs most implicated. Consistent with our hypothesis, we found a significantly higher proportion of individuals in the schizophrenia than in the non-psychotic group to have an additional rare CNV that overlapped one or more miRNA target genes (odds ratio = 2.12, p = 0.0138). Gene set analyses identified an enrichment of FMRP targets and genes involved in nervous system development and postsynaptic density amongst these miRNA target genes in the schizophrenia group. The miRNAs most implicated included miR-17-5p, miR-34a-5p and miR-124-3p. These results provide initial correlational evidence in support of a possible role for miRNA perturbation involving genes affected by rare genome-wide CNVs in the elevated risk for schizophrenia in 22q11.2DS, consistent with the multi-hit and multi-layered genetic mechanisms implicated in this and other forms of schizophrenia.

miR-129 Promotes the Proliferation of Alzheimer’s Neuronal Cells by Binding the 3′ Untranslated Regions (3′ UTR) of Amyloid Precursor Protein (APP)

Alzheimer’s disease (AD) is a neurodegenerative disease with memory loss and cognitive impairment. Short non-coding RNAs (miRNAs) are potential biomarkers and therapeutic targets for AD. This study aims to investigate miR-129’s role in AD. miR-129 and amyloid precursor protein (APP) expression was measured by Q-PCR, and LC3, p62, ATG5, Bcl-2, p-Tau and Caspase3 protein was detected by Western blot. Hydrogenase kits and DCFH-DA detected cell apoptosis, cytotoxicity and ROS generation. The interaction between APP and miR-129 was assessed by luciferase report experiment. HE staining and TUNEL assay evaluated hippocampal neuron damage. In AD patient serum, AD transgenic (TG) mouse brain tissue, and AB1-42-treated SH-SY5Y cells, miR-129 was downregulated but autophagy was increased. Overexpression of miR-129 reduced cell damage induced by AB1-42, and miR-129 can directly regulate APP expression by binding APP 3′-UTR. miR-129 inhibitors reversed the protective effect of shAPP on AB1-42-induced cell damage. In addition, miR-129 overexpression reduced neuronal damage through inhibiting autophagy in vivo. APP expression in AD patient and AD cell model was significantly increased compared to controls. Aβ-42 treatment caused up-regulation of APP expression, while APP knockdown inhibited neurons through autophagy. In conclusion, miR-129 overexpression can regulate autophagy by targeting APP5, thereby reducing neuronal damage in AD. These findings provide a new perspective for treating AD.

Integrated Analysis of miRNA and mRNA Expression Profiles Reveals the Molecular Mechanism of Posttraumatic Stress Disorder and Therapeutic Drugs

Purpose

Post-traumatic stress disorder (PTSD) is a result of trauma exposure and is related to psychological suffering as a long-lasting health issue. Further analysis of the networks and genes involved in PTSD are critical to the molecular mechanisms of PTSD.

Methods

In this study, we aimed to identify key genes and molecular interaction networks involved in the pathogenesis of PTSD by integrating mRNA and miRNA data.

Results

By integrating three high-throughput datasets, 5606 differentially expressed genes (DEGs) were detected, including five differentially expressed miRNAs (DEmiRNAs) and 5525 differentially expressed mRNAs (DEmRNAs). Nineteen upregulated and 46 downregulated DEmRNAs were identified in both GSE64813 and GSE89866 datasets, while five upregulated DEmiRNAs were found in the GSE87768 dataset. Functional annotations of these DEmRNAs indicated that they were mainly enriched in blood coagulation, cell adhesion, platelet activation, and extracellular matrix (ECM)-receptor interaction. Integrated protein-protein and miRNA-protein interaction networks among the DEGs were established with the help of 65 nodes and 121 interactions. Finally, 286 small molecules were obtained based on the Drug-Gene Interaction database (DGIdb). Three genes, prostaglandin-endoperoxide synthase 1 (PTGS1), beta-tubulin gene (TUBB1), and cyclin-dependent kinase inhibitor 1A (CDKN1A), were the most promising targets for PTSD therapy. Additionally, the present study also provided a higher performance diagnostic model for PTSD based on 17 DEmRNAs, which was validated in two independent datasets, GSE109409 and GSE63878.

Conclusion

Our data provides a new molecular aspect that ECM-receptor interaction and the platelet activation process could be the potential molecular mechanism of PTSD, and the genes involved in this process may be promising therapeutic targets. A higher-performance diagnostic model for PTSD has also been identified.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

Cerebrospinal Fluid MicroRNA Changes in Cognitively Normal Veterans With a History of Deployment-Associated Mild Traumatic Brain Injury

A history of traumatic brain injury (TBI) increases the odds of developing Alzheimer's disease (AD). The long latent period between injury and dementia makes it difficult to study molecular changes initiated by TBI that may increase the risk of developing AD. MicroRNA (miRNA) levels are altered in TBI at acute times post-injury (<4 weeks), and in AD. We hypothesized that miRNA levels in cerebrospinal fluid (CSF) following TBI in veterans may be indicative of increased risk for developing AD. Our population of interest is cognitively normal veterans with a history of one or more mild TBI (mTBI) at a chronic time following TBI. We measured miRNA levels in CSF from three groups of participants: (1) community controls with no lifetime history of TBI (ComC); (2) deployed Iraq/Afghanistan veterans with no lifetime history of TBI (DepC), and (3) deployed Iraq/Afghanistan veterans with a history of repetitive blast mTBI (DepTBI). CSF samples were collected at the baseline visit in a longitudinal, multimodal assessment of Gulf War veterans, and represent a heterogenous group of male veterans and community controls. The average time since the last blast mTBI experienced was 4.7 ± 2.2 years [1.5 - 11.5]. Statistical analysis of TaqMan^TM miRNA array data revealed 18 miRNAs with significant differential expression in the group comparisons: 10 between DepTBI and ComC, 7 between DepC and ComC, and 8 between DepTBI and DepC. We also identified 8 miRNAs with significant differential detection in the group comparisons: 5 in DepTBI vs. ComC, 3 in DepC vs. ComC, and 2 in DepTBI vs. DepC. When we applied our previously developed multivariable dependence analysis, we found 13 miRNAs (6 of which are altered in levels or detection) that show dependencies with participant phenotypes, e.g., ApoE. Target prediction and pathway analysis with miRNAs differentially expressed in DepTBI vs. either DepC or ComC identified canonical pathways highly relevant to TBI including senescence and ephrin receptor signaling, respectively. This study shows that both TBI and deployment result in persistent changes in CSF miRNA levels that are relevant to known miRNA-mediated AD pathology, and which may reflect early events in AD.