Selective distribution and dynamic modulation of miRNAs in the synapse and its possible role in Alzheimer's Disease

MicroRNAs as Diagnostic Biomarkers and Predictors of Antidepressant Response in Major Depressive Disorder: A Systematic Review

Despite the hardships of major depressive disorder (MDD), biomarkers for the diagnosis and pharmacological management of this condition are lacking. MicroRNAs are epigenetic mechanisms that could provide promising MDD biomarkers. Our aim was to summarize the findings and provide validation for the selection and use of specific microRNAs as biomarkers in the diagnosis and treatment of MDD. A systematic review was conducted using the PubMed/Medline, Cochrane, PsycINFO, Embase, and LILACS databases from March 2022 to November 2023, with clusters of terms based on "microRNA" and "antidepressant". Studies involving human subjects, animal models, and cell cultures were included, whereas those that evaluated herbal medicines, non-pharmacological therapies, or epigenetic mechanisms other than miRNA were excluded. The review revealed differences in the expression of various microRNAs when considering the time of assessment (before or after antidepressant treatment) and the population studied. However, due to the heterogeneity of the microRNAs investigated, the limited size of the samples, and the wide variety of antidepressants used, few conclusions could be made. Despite the observed heterogeneity, the following microRNAs were determined to be important factors in MDD and the antidepressant response: mir-1202, mir-135, mir-124, and mir-16. The findings indicate the potential for the use of microRNAs as biomarkers for the diagnosis and treatment of MDD; however, more homogeneous studies are needed.

Identification of potential therapeutic and diagnostic characteristics of Alzheimer disease by targeting the miR-132-3p/FOXO3a-PPM1F axis in APP/PS1 mice

Alzheimer disease (AD) is a neurodegenerative disorder, which is characterized by progressive impairment of memory and cognition. Early diagnosis and treatment of AD has become a leading topic of research. In this study, we explored the effects of the miR-132-3p/FOXO3a-PPM1F axis on the onset of AD for possible early diagnosis and therapy. We found that miR-132-3p levels in the hippocampus and blood were drastically decreased in APP/PS1 mice from 9 months of age, and bi-directional manipulation of miR-132-3p levels induced magnified effects on learning memory behaviors, and manifestation of AD-related pathological characteristics and inflammatory cytokines in APP/PS1 mice of relevant ages. The hippocampal PPM1F expression levels were significantly elevated in APP/PS1 mice from 3 months of age, which was correlated with miR-132-3p levels at different ages. Overexpression of PPM1F remarkably accelerated the progression of learning memory deficits and associated pathological factors in APP/PS1 mice. Further, we showed that miR-132-3p modulated the expression of PPM1F via FOXO3a in HT22 cells. Finally, using peripheral blood samples of human study participants, we found that the miR-132-3p and PPM1F expression levels in patients with AD were also altered with prominent correlations. In conclusion, miR-132-3p indirectly regulates PPM1F expression by targeting FOXO3a, which could play an extensive role in contributing to the establishment of early diagnosis, treatment, and pathogenesis of AD.

Epigenetic marks in suicide: a review

Suicide is a complex phenomenon and a global public health problem that involves several biological factors that could contribute to the pathophysiology of suicide. There is evidence that epigenetic factors influence some psychiatric disorders, suggesting a predisposition to suicide or suicidal behavior. Here, we review studies of molecular mechanisms of suicide in an epigenetic perspective in the postmortem brain of suicide completers and peripheral blood cells of suicide attempters. Besides, we include studies of gene-specific DNA methylation, epigenome-wide association, histone modification, and interfering RNAs as epigenetic factors. This review provides an overview of the epigenetic mechanisms described in different biological systems related to suicide, contributing to an understanding of the genetic regulation in suicide. We conclude that epigenetic marks are potential biomarkers in suicide, and they could become attractive therapeutic targets due to their reversibility and importance in regulating gene expression.

The Association Between Circulating Klotho and Dipeptidyl Peptidase-4 Activity and Inflammatory Cytokines in Elderly Patients With Alzheimer Disease

Introduction:

Klotho and Dipeptidyl Peptidase-4 (DPP4) are two proteins that modulate inflammatory pathways. We investigated the association between circulating klotho and DPP4 activity and their relationship with inflammatory cytokines, miR-29a, and miR-195 in Alzheimer Disease (AD).

Methods:

This study was conducted on 16 AD patients and 16 healthy age-matched controls. Plasma levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β, interleukin-6 (IL-6), klotho, and DPP4 were measured by enzyme-linked immunosorbent assay. Plasma expression of miR-29a and miR-195 were also measured and compared by a real-time polymerase chain reaction.

Results:

There was a significant increase in TNF-α (p=0.006), IL-1β (p=0.012), and IL-6 (p=0.012) levels in the AD subjects compared with controls. Also, we found a decrease in plasma levels of klotho and an increase in plasma levels of DPP4 in the AD group that was not significant compared with the controls. Lower expression of miR-29a (P=0.009) and higher expression of miR-195 (P=0.003) were observed in the AD group that was significant than controls. Further analysis showed a negative correlation between klotho and plasma levels of IL-6 (r=−0.58, p=0.01). Also, there was a positive correlation between plasma DPP4 activity and TNF-α levels (r=0.50, P=0.04) and IL-1β (r=0.62, P=0.01). Likewise, plasma klotho concentration showed a negative correlation with the age of AD subjects (r=−0.56, P=0.02).

Conclusion:

TNF-α, IL-1β, and IL-6 are involved in AD pathophysiology, and dysregulation of DPP4 and klotho may be associated with the inflammatory response of AD. Down-regulation of miR-29a and up-regulation of miR-195 indicated the role of miRNAs in the AD process.

Environmental enrichment prevents Aβ oligomer-induced synaptic dysfunction through mirna-132 and hdac3 signaling pathways

As the most common cause of progressive cognitive decline in humans, Alzheimer's disease (AD) has been intensively studied, but the mechanisms underlying its profound synaptic dysfunction remain unclear. Here we confirm that exposing wild-type mice to an enriched environment (EE) facilitates signaling in the hippocampus that promotes long-term potentiation (LTP). Exposing the hippocampus of mice kept in standard housing to soluble Aβ oligomers impairs LTP, but EE can fully prevent this. Mechanistically, the key molecular features of the EE benefit are an upregulation of miRNA-132 and an inhibition of histone deacetylase (HDAC) signaling. Specifically, soluble Aβ oligomers decreased miR-132 expression and increased HDAC3 levels in cultured primary neurons. Further, we provide evidence that HDAC3 is a direct target of miR-132. Overexpressing miR-132 or injecting an HDAC3 inhibitor into mice in standard housing mimics the benefits of EE in enhancing hippocampal LTP and preventing hippocampal impairment by Aβ oligomers in vivo. We conclude that EE enhances hippocampal synaptic plasticity by upregulating miRNA-132 and reducing HDAC3 signaling in a way that counteracts the synaptotoxicity of human Aβ oligomers. Our findings provide a rationale for prolonged exposure to cognitive novelty and/or epigenetic modulation to lessen the progressive effects of Aβ accumulation during human brain aging.

Hippocampal stem cells promotes synaptic resistance to the dysfunctional impact of amyloid beta oligomers via secreted exosomes

BACKGROUND

Adult hippocampal neurogenesis plays an important role in synaptic plasticity and cogntive function. We reported that higher numbers of neural stem cells (NSC) in the hippocampus of cognitively-intact individuals with high Alzheimer's disease (AD) pathology (plaques and tangles) is associated with decreased synaptic amyloid beta oligomers (Aβο), an event linked to onset of dementia in AD. While these findings suggest a link between NSC and synaptic resistance to Aβο, the involved mechanism remains to be determined. With this goal in mind, here we investigated the ability of exosomes secreted from hippocampal NSC to promote synaptic resilience to Aβo.

METHODS

Exosomes isolated from media of hippocampus NSC (NSC-exo) or mature hippocampal neuronal (MN-exo) cultures were delivered intracerebroventricularly (ICV) to mice before assessment of Aβο-induced suppression of hippocampal long-term potentiation (LTP) and memory deficits. Aβο binding to synapses was assessed in cultured hippocampal neurons and on synaptosomes isolated from hippocampal slices from wild type mice and from an inducible mouse model of NSC ablation (Nestin-δ-HSV-TK mice) treated with exosomes. Expression of CaMKII and of AMPA and NMDA glutamate receptor subunits in synaptosomes was measured by western blot. Small RNA Deep sequencing was performed to identify microRNAs enriched in NSC-exo as compared to MN-exo. Mimics of select miRNAs were injected ICV.

RESULTS

NSC-exo, but not MN-exo, abolished Aβo-induced suppression of LTP and subsequent memory deficits. Furthermore, in hippocampal slices and cultured neurons, NSC-exo significantly decreased Aβo binding to the synapse. Similarly, transgenic ablation of endogenous NSC increased synaptic Aβo binding, which was reversed by exogenous NSC-exo. Phosphorylation of synaptic CaMKII was increased by NSC-exo, while AMPA and NMDA receptors were not affected. Lastly, we identified a set of miRNAs enriched in NSC-exo that, when injected ICV, protected the synapses from Aβo-binding and Aβo-induced LTP inhibition.

CONCLUSIONS

These results identify a novel mechanism linking NSC-exo and synaptic susceptibility to Aβo that may underscore cognitive resilience of certain individuals with increased neurogenesis in spite of AD neuropathology and unmask a novel target for the development of a new treatment concept for AD centered on promoting synaptic resilience to toxic amyloid proteins.

Differential MicroRNA Analyses of Burkholderia pseudomallei- and Francisella tularensis-Exposed hPBMCs Reveal Potential Biomarkers

Increasing evidence that microRNAs (miRNAs) play important roles in the immune response against infectious agents suggests that miRNA might be exploitable as signatures of exposure to specific infectious agents. In order to identify potential early miRNA biomarkers of bacterial infections, human peripheral blood mononuclear cells (hPBMCs) were exposed to two select agents, Burkholderia pseudomallei K96243 and Francisella tularensis SHU S4, as well as to the nonpathogenic control Escherichia coli DH5α. RNA samples were harvested at three early time points, 30, 60, and 120 minutes postexposure, then sequenced. RNAseq analyses identified 87 miRNAs to be differentially expressed (DE) in a linear fashion. Of these, 31 miRNAs were tested using the miScript miRNA qPCR assay. Through RNAseq identification and qPCR validation, we identified differentially expressed miRNA species that may be involved in the early response to bacterial infections. Based upon its upregulation at early time points postexposure in two different individuals, hsa-mir-30c-5p is a miRNA species that could be studied further as a potential biomarker for exposure to these gram-negative intracellular pathogens. Gene ontology functional analyses demonstrated that programmed cell death is the first ranking biological process associated with miRNAs that are upregulated in F. tularensis-exposed hPBMCs.

Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review

The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.

Depleted uranium induces sex- and tissue-specific methylation patterns in adult zebrafish

We examined the effects of chronic exposure to different concentrations (2 and 20 μg L(-)(1)) of environmentally relevant waterborne depleted uranium (DU) on the DNA methylation patterns both at HpaII restriction sites (5'-CCGG-3') and across the whole genome in the zebrafish brain, gonads, and eyes. We first identified sex-dependent differences in the methylation level of HpaII sites after exposure. In males, these effects were present as early as 7 days after exposure to 20 μg L(-)(1) DU, and were even more pronounced in the brain, gonads, and eyes after 24 days. However, in females, hypomethylation was only observed in the gonads after exposure to 20 μg L(-)(1) DU for 24 days. Sex-specific effects of DU were also apparent at the whole-genome level, because in males, exposure to 20 μg L(-)(1) DU for 24 days resulted in cytosine hypermethylation in the brain and eyes and hypomethylation in the gonads. In contrast, in females, hypermethylation was observed in the brain after exposure to both concentrations of DU for 7 days. Based on our current knowledge of uranium toxicity, several hypotheses are proposed to explain these findings, including the involvement of oxidative stress, alteration of demethylation enzymes and the calcium signaling pathway. This study reports, for the first time, the sex- and tissue-specific epigenetic changes that occur in a nonhuman organism after exposure to environmentally relevant concentrations of uranium, which could induce transgenerational epigenetic effects.

The biomarker and therapeutic potential of miRNA in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia. Currently, a clinical diagnosis of AD is based on evidence of both cognitive and functional decline. Progression is monitored by detailed clinical evaluations over many months to years. It is increasingly clear that to advance disease-modifying therapies for AD, patients must be identified and treated early, before obvious cognitive and functional changes. In addition, better methods are needed to sensitively monitor progression of disease and therapeutic efficacy. Therefore, considerable research has focused on characterizing biomarkers that can identify the disease early as well as accurately monitor disease progression. miRNA offer a unique opportunity for biomarker development. Here, we review research focused on characterizing miRNA as potential biomarkers and as a treatment for disease.

Pathogenetic and therapeutic applications of microRNAs in major depressive disorder

As a class of noncoding RNAs, microRNAs (miRNAs) regulate gene expression by inhibiting translation of messenger RNAs. These miRNAs have been shown to play a critical role in higher brain functioning and actively participate in synaptic plasticity. Pre-clinical evidence demonstrates that expression of miRNAs is differentially altered during stress. On the other hand, depressed individuals show marked changes in miRNA expression in brain. MiRNAs are also target of antidepressants and electroconvulsive therapy. Moreover, these miRNAs are present in circulating blood and can be easily detected. Profiling of miRNAs in blood plasma/serum provides evidence that determination of miRNAs in blood can be used as possible diagnostic and therapeutic tool. In this review article, these aspects are critically reviewed and the role of miRNAs in possible etiopathogenesis and therapeutic implications in the context of major depressive disorder is discussed.

MicroRNA abundance is altered in synaptoneurosomes during prion disease

Discrepancy in synaptic structural plasticity is one of the earliest manifestations of the neurodegenerative state. In prion diseases, a reduction in synapses and dendritic spine densities is observed during preclinical disease in neurons of the cortex and hippocampus. The underlying molecular mechanisms of these alterations have not been identified but microRNAs (miRNAs), many of which are enriched at the synapse, likely regulate local protein synthesis in rapid response to stressors such as replicating prions. MiRNAs are therefore candidate regulators of these early neurodegenerative changes and may provide clues as to the molecular pathways involved. We therefore determined changes in mature miRNA abundance within synaptoneurosomes isolated from prion-infected, as compared to mock-infected animals, at asymptomatic and symptomatic stages of disease. During preclinical disease, miRNAs that are enriched in neurons including miR-124a-3p, miR-136-5p and miR-376a-3p were elevated. At later stages of disease we found increases in miRNAs that have previously been identified as deregulated in brain tissues of prion infected mice, as well as in Alzheimer's disease (AD) models. These include miR-146a-5p, miR-142-3p, miR-143-3p, miR-145a-5p, miR-451a, miR-let-7b, miR-320 and miR-150-5p. A number of miRNAs also decreased in abundance during clinical disease. These included almost all members of the related miR-200 family (miR-200a-3p, miR-200b-3p, miR-200c-3p, miR-141-3p, and miR-429-3p) and the 182 cluster (miR-182-5p and miR-183-5p).

Neuronopathic Gaucher disease: dysregulated mRNAs and miRNAs in brain pathogenesis and effects of pharmacologic chaperone treatment in a mouse model

Defective lysosomal acid β-glucosidase (GCase) in Gaucher disease causes accumulation of glucosylceramide (GC) and glucosylsphingosine (GS) that distress cellular functions. To study novel pathological mechanisms in neuronopathic Gaucher disease (nGD), a mouse model (4L;C*), an analogue to subacute human nGD, was investigated for global profiles of differentially expressed brain mRNAs (DEGs) and miRNAs (DEmiRs). 4L;C* mice displayed accumulation of GC and GS, activated microglial cells, reduced number of neurons and aberrant mitochondrial function in the brain followed by deterioration in motor function. DEGs and DEmiRs were characterized from sequencing of mRNA and miRNA from cerebral cortex, brain stem, midbrain and cerebellum of 4L;C* mice. Gene ontology enrichment and pathway analysis showed preferential mitochondrial dysfunction in midbrain and uniform inflammatory response and identified novel pathways, axonal guidance signaling, synaptic transmission, eIF2 and mammalian target of rapamycin (mTOR) signaling potentially involved in nGD. Similar analyses were performed with mice treated with isofagomine (IFG), a pharmacologic chaperone for GCase. IFG treatment did not alter the GS and GC accumulation significantly but attenuated the progression of the disease and altered numerous DEmiRs and target DEGs to their respective normal levels in inflammation, mitochondrial function and axonal guidance pathways, suggesting its regulation on miRNA and the associated mRNA that underlie the neurodegeneration in nGD. These analyses demonstrate that the neurodegenerative phenotype in 4L;C* mice was associated with dysregulation of brain mRNAs and miRNAs in axonal guidance, synaptic plasticity, mitochondria function, eIF2 and mTOR signaling and inflammation and provides new insights for the nGD pathological mechanism.

Methods and compositions for amplification and detection of microRNAs (miRNAs) and noncoding RNAs (ncRNAs) using the signature sequence amplification method (SSAM)

The signature sequence amplification method (SSAM) described herein is an approach for amplifying noncoding RNA (ncRNA), microRNA (miRNA), and small polynucleotide sequences. A key point of the SSAM technology is the generation of signature sequences. The signature sequences include target sequences (miRNA, ncRNA, and/or any small polynucleotide sequence) flanked by two DNA fragments. Target sequences can be amplified through DNA synthesis, RNA synthesis, or the combination of DNA and RNA synthesis. The amplification of signature sequences provides an efficient and reproducible mechanism to determine the presence or absence of the target miRNAs/ncRNAs, to analyze the quantities of the miRNAs in biological samples, and for miRNA/ncRNA profiling.

The epigenetic dimension of Alzheimer's disease: causal, consequence, or curiosity?

Early-onset, familial Alzheimer's disease (AD) is rare and may be attributed to disease-causinq mutations. By contrast, late onset, sporadic (non-Mendelian) AD is far more prevalent and reflects the interaction of multiple genetic and environmental risk factors, together with the disruption of epigenetic mechanisms controlling gene expression. Accordingly, abnormal patterns of histone acetylation and methylation, as well as anomalies in global and promoter-specific DNA methylation, have been documented in AD patients, together with a deregulation of noncoding RNA. In transgenic mouse models for AD, epigenetic dysfunction is likewise apparent in cerebral tissue, and it has been directly linked to cognitive and behavioral deficits in functional studies. Importantly, epigenetic deregulation interfaces with core pathophysiological processes underlying AD: excess production of Aβ42, aberrant post-translational modification of tau, deficient neurotoxic protein clearance, axonal-synaptic dysfunction, mitochondrial-dependent apoptosis, and cell cycle re-entry. Reciprocally, DNA methylation, histone marks and the levels of diverse species of microRNA are modulated by Aβ42, oxidative stress and neuroinflammation. In conclusion, epigenetic mechanisms are broadly deregulated in AD mainly upstream, but also downstream, of key pathophysiological processes. While some epigenetic shifts oppose the evolution of AD, most appear to drive its progression. Epigenetic changes are of irrefutable importance for AD, but they await further elucidation from the perspectives of pathogenesis, biomarkers and potential treatment.

MicroRNA-138 promotes tau phosphorylation by targeting retinoic acid receptor alpha

Alzheimer's disease (AD) is a progressive neurodegenerative dementia characterized by Aβ deposition and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau. Emerging evidence shows that microRNAs (miRNAs) contribute to the pathogenesis of AD. Herein, we investigated the role of miR-138, a brain enriched miRNA, which is increased in AD patients. We found that miR-138 is increased in AD models, including N2a/APP and HEK293/tau cell lines. Overexpression of miR-138 activates glycogen synthase kinase-3β (GSK-3β), and increases tau phosphorylation in HEK293/tau cells. Furthermore, we confirm that retinoic acid receptor alpha (RARA) is a direct target of miR-138, and supplement of RARA substantially suppresses GSK-3β activity, and reduces tau phosphorylation induced by miR-138. In conclusion, our data suggest that miR-138 promotes tau phosphorylation by targeting the RARA/GSK-3β pathway.

Protective Properties of Neural Extracellular Matrix

The extracellular matrix (ECM) of the central nervous system (CNS) occupies a large part of the neural tissue. It serves a variety of functions ranging from support of cell migration and regulating synaptic transmission and plasticity to the active modulation of the neural tissue after injury. In addition, evidence for neuroprotective properties of ECM components has accumulated more recently. In contrast to other connective tissues, the central nervous ECM is mainly composed of glycosaminoglycans, which can be present unbound in the form of hyaluronan or bound to proteins, thus forming proteoglycans. A subtype of this molecular family are the chondroitin sulphate proteoglycans (CSPGs), which are composed of a core protein that carries at least one covalently bound glycosaminoglycan side chain with a certain degree of sulphation. Several studies could show neuroprotective features of CSPGs against excitotoxicity, amyloid-ß toxicity, or oxidative stress. Recently, we could provide evidence for a neuroprotective function of a specialized form of ECM, the so-called perineuronal net ensheathing a subtype of neurons. Here, we will give an overview on recently emerging aspects of neuroprotective properties of CSPGs and perineuronal nets that might be relevant for our understanding on the distribution and progression of brain pathology and future perspectives toward modifying neurodegenerative diseases.

miRNA Temporal Analyzer (mirnaTA): a bioinformatics tool for identifying differentially expressed microRNAs in temporal studies using normal quantile transformation

Background

Understanding the biological roles of microRNAs (miRNAs) is a an active area of research that has produced a surge of publications in PubMed, particularly in cancer research. Along with this increasing interest, many open-source bioinformatics tools to identify existing and/or discover novel miRNAs in next-generation sequencing (NGS) reads become available. While miRNA identification and discovery tools are significantly improved, the development of miRNA differential expression analysis tools, especially in temporal studies, remains substantially challenging. Further, the installation of currently available software is non-trivial and steps of testing with example datasets, trying with one’s own dataset, and interpreting the results require notable expertise and time. Subsequently, there is a strong need for a tool that allows scientists to normalize raw data, perform statistical analyses, and provide intuitive results without having to invest significant efforts.

Findings

We have developed miRNA Temporal Analyzer (mirnaTA), a bioinformatics package to identify differentially expressed miRNAs in temporal studies. mirnaTA is written in Perl and R (Version 2.13.0 or later) and can be run across multiple platforms, such as Linux, Mac and Windows. In the current version, mirnaTA requires users to provide a simple, tab-delimited, matrix file containing miRNA name and count data from a minimum of two to a maximum of 20 time points and three replicates. To recalibrate data and remove technical variability, raw data is normalized using Normal Quantile Transformation (NQT), and linear regression model is used to locate any miRNAs which are differentially expressed in a linear pattern. Subsequently, remaining miRNAs which do not fit a linear model are further analyzed in two different non-linear methods 1) cumulative distribution function (CDF) or 2) analysis of variances (ANOVA). After both linear and non-linear analyses are completed, statistically significant miRNAs (P < 0.05) are plotted as heat maps using hierarchical cluster analysis and Euclidean distance matrix computation methods.

Conclusions

mirnaTA is an open-source, bioinformatics tool to aid scientists in identifying differentially expressed miRNAs which could be further mined for biological significance. It is expected to provide researchers with a means of interpreting raw data to statistical summaries in a fast and intuitive manner.

The effect of neuropeptide Y on cell survival and neurotrophin expression in in-vitro models of Alzheimer's disease

Alzheimer's disease (AD) is a disorder characterized by the accumulation of abnormally folded protein fragments in neurons, i.e., β-amyloid (Aβ) and tau protein, leading to cell death. Several neuropeptides present in the central nervous system (CNS) are believed to be involved in the pathophysiology of AD. Among them, neuropeptide Y (NPY), a small peptide widely distributed throughout the brain, has generated interest because of its role in neuroprotection against excitotoxicity in animal models of AD. In addition, it has been shown that NPY modulates neurogenesis. Interestingly, these latter effects are similar to those elicited by neurotrophins, which are critical molecules for the function and survival of neurons that degenerate during the course of AD. In this review we summarize the evidence for the involvement of NPY and neurotrophins in AD pathogenesis, and the similarity between them in CNS neurons. Finally, we recapitulate our recent in-vitro evidence for the involvement of neurotrophin nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in the neuroprotective effect elicited by NPY in AD neuron-like models (neuroblastoma cells or primary cultures exposed to toxic concentrations of Aβ's pathogenic fragment 25-35), and propose a putative mechanism based on NPY-induced inhibition of voltage-dependent Ca(2+) influx in pre- and post-synaptic neurons.

Point-of-care diagnostic tools to detect circulating microRNAS as biomarkers of disease

MicroRNAs or miRNAs are a form of small non-coding RNAs (ncRNAs) of 19–22 nucleotides in length in their mature form. miRNAs are transcribed in the nucleus of all cells from large precursors, many of which have several kilobases in length. Originally identified as intracellular modulators of protein synthesis via posttranscriptional gene silencing, more recently it has been found that miRNAs can travel in extracellular human fluids inside specialized vesicles known as exosomes. We will be referring to this miRNAs as circulating microRNAs. More interestingly, the miRNA content inside exosomes changes during pathological events. In the present review we analyze the literature about circulating miRNAs and their possible use as biomarkers. Furthermore, we explore their future in point-of-care (POC) diagnostics and provide an example of a portable POC apparatus useful in the detection of circulating miRNAs.