Novel BDNF-regulatory microRNAs in neurodegenerative disorders pathogenesis: An in silico study

Genetic and epigenetic targets of natural dietary compounds as anti-Alzheimer's agents

Alzheimer's disease is a progressive neurodegenerative disorder and the most common cause of dementia that principally affects older adults. Pathogenic factors, such as oxidative stress, an increase in acetylcholinesterase activity, mitochondrial dysfunction, genotoxicity, and neuroinflammation are present in this syndrome, which leads to neurodegeneration. Neurodegenerative pathologies such as Alzheimer's disease are considered late-onset diseases caused by the complex combination of genetic, epigenetic, and environmental factors. There are two main types of Alzheimer's disease, known as familial Alzheimer's disease (onset < 65 years) and late-onset or sporadic Alzheimer's disease (onset ≥ 65 years). Patients with familial Alzheimer's disease inherit the disease due to rare mutations on the amyloid precursor protein (APP), presenilin 1 and 2 (PSEN1 and PSEN2) genes in an autosomal-dominantly fashion with closely 100% penetrance. In contrast, a different picture seems to emerge for sporadic Alzheimer's disease, which exhibits numerous non-Mendelian anomalies suggesting an epigenetic component in its etiology. Importantly, the fundamental pathophysiological mechanisms driving Alzheimer's disease are interfaced with epigenetic dysregulation. However, the dynamic nature of epigenetics seems to open up new avenues and hope in regenerative neurogenesis to improve brain repair in Alzheimer's disease or following injury or stroke in humans. In recent years, there has been an increase in interest in using natural products for the treatment of neurodegenerative illnesses such as Alzheimer's disease. Through epigenetic mechanisms, such as DNA methylation, non-coding RNAs, histone modification, and chromatin conformation regulation, natural compounds appear to exert neuroprotective effects. While we do not purport to cover every in this work, we do attempt to illustrate how various phytochemical compounds regulate the epigenetic effects of a few Alzheimer's disease-related genes.

Long non coding RNA COX10-DT promotes the progression of breast cancer via the COX10-DT/miR-206/BDNF axis

Long noncoding RNAs (lncRNAs) are emerging as critical regulators in the biological development of breast cancer. In this study, we aimed to determine the roles and mechanisms of the lncRNA COX10 divergent transcript (COX10-DT) in breast cancer progression. The relative expression level of COX10-DT was calculated in matched breast cancer tissues and adjacent normal tissues using quantitative real-time PCR. Gain-of-function and loss-of-function approaches further revealed the functions and mechanisms of COX10-DT in breast cancer cells. Clinically, we found that the lncRNA COX10-DT was commonly overexpressed in breast cancer tissues compared to paired peritumoural tissues. Functionally, the lncRNA COX10-DT might promote the proliferation and migration of breast cancer cells. Mechanistically, the lncRNA COX10-DT did not play a role by regulating the expression of its divergent gene COX10 but acted as a competitive endogenous RNA (ceRNA) by directly sponging miR-206, which further regulated the expression of brain-derived neurotrophic factor (BDNF). Taken together, our results proved that the lncRNA COX10-DT could function via the COX10-DT/miR-206/BDNF axis, thereby promoting the development of breast cancer. These findings indicated that the lncRNA COX10-DT might be a potential biomarker and therapeutic target for breast cancer.

miR-182-5p combined with brain-derived neurotrophic factor assists the diagnosis of chronic heart failure and predicts a poor prognosis

Objective

Chronic heart failure (CHF) is a general progressive disorder with high morbidity and poor prognosis. This study analyzed the serum expression and clinical value of miR-182-5p and brain-derived neurotrophic factor (BDNF) in CHF patients.

Methods

A total of 82 CHF patients were selected as the study subjects (15 cases in NYHA stage I, 29 cases in stage II, 27 cases in stage III, and 11 cases in stage IV), with another 78 healthy people as the controls. The expression of serum miR-182-5p was detected by RT-qPCR. BDNF expression was measured by ELISA. Furthermore, the Pearson coefficient was used to analyze the correlation of miR-182-5p/BDNF with BNP and LVEF. ROC curve was employed to assess the potential of miR-182-5p or/and BDNF for the diagnosis of CHF. Kaplan–Meier survival curve was implemented to evaluate the prognostic value of miR-182-5p and BDNF.

Results

Serum miR-182-5p level was elevated and BDNF expression was lowered in CHF patients. Serum miR-182-5p in CHF patients was positively-related with BNP and inversely-correlated with LVEF, while serum BDNF was negatively-linked with BNP and positively-correlated with LVEF. ROC curve indicated the diagnostic value of serum miR-182-5p and BDNF for CHF and the diagnostic accuracy of miR-182-5p combined with BDNF was improved. Kaplan–Meier analysis unveiled that miR-182-5p low expression and BDNF high expression could predict the overall survival in CHF patients.

Conclusion

miR-182-5p expression is increased and BDNF level is decreased in CHF patients. miR-182-5p combined with BDNF can assist the diagnosis of CHF and predict a poor prognosis.

MicroRNA editing patterns in Huntington's disease

Huntington’s disease (HD) is a neurodegenerative disease. MicroRNAs (miRNAs) are small non-coding RNAs that mediate post-transcriptional regulation of target genes. Although miRNAs are extensively edited in human brains, the editome of miRNAs in brains of HD patients is largely unknown. By analyzing the small RNA sequencing profiles of brain tissues of 28 HD patients and 83 normal controls, 1182 miRNA editing sites with significant editing levels were identified. In addition to 27 A-to-I editing sites, we identified 3 conserved C-to-U editing sites in miRNAs of HD patients. 30 SNPs in the miRNAs of HD patients were also identified. Furthermore, 129 miRNA editing events demonstrated significantly different editing levels in prefrontal cortex samples of HD patients (HD-PC) when compared to those of healthy controls. We found that hsa-mir-10b-5p was edited to have an additional cytosine at 5’-end in HD-PC, and the edited hsa-mir-10b repressed GTPBP10 that was often downregulated in HD. The down-regulation of GTPBP10 might contribute to the progression of HD by causing gradual loss of function of mitochondrial. These results provide the first endeavor to characterize the miRNA editing events in HD and their potential functions.

The adenosine A2A receptor antagonist protects against retinal mitochondrial injury in association with an altered network of competing endogenous RNAs

Blockade of adenosine A_2A receptors (A_2ARs) protects against neuronal damage caused by various brain insults including mitochondrial toxicity, but the precise neuroprotective mechanisms are unclear. Here, we studied the effects of the A_2AR antagonist KW6002 on retinal injury induced by the mitochondrial oxidative phosphorylation uncoupler, carbonylcyanide m-chlorophenyl hydrazine (CCCP) and alterations in competing endogenous RNA (ceRNA) network. We found that KW6002 treatment partially reversed CCCP-induced reduction in retinal thickness and retinal ganglia cell number by increasing mitochondrial content and reducing retinal ganglia cells apoptosis. Furthermore, we employed whole-transcriptome sequencing to explore ceRNA network changes associated with CCCP-induced retinal injury and its reversal by KW6002. This analysis revealed that A_2AR blockade reduced the number of CCCP-induced microRNAs by ∼60%, but increased the number of CCCP-induced circular RNAs by ∼50%. Among CeRNA network changes, CCCP-induced retinal injury was associated with a possible enrichment of the tumor necrosis factor signaling pathway and its related 126 microRNAs, 237 long non-coding RNAs, 58 circular RNAs competing. Moreover, the A_2AR antagonist-mediated protection against CCCP-induced retinal injury was possibly associated with the up-regulation of mature brain-derived neurotrophic factor and its related 4 microRNAs competed by 43 long non-coding RNAs and 9 circular RNAs competing. These ceRNA network alterations by CCCP treatment and its reversal by A_2AR antagonist may contribute to understanding the transcriptome mechanism for protection against CCCP-induced retinal injury by A_2AR antagonists.

Neurobiological Highlights of Cognitive Impairment in Psychiatric Disorders

This review is focused on several psychiatric disorders in which cognitive impairment is a major component of the disease, influencing life quality. There are plenty of data proving that cognitive impairment accompanies and even underlies some psychiatric disorders. In addition, sources provide information on the biological background of cognitive problems associated with mental illness. This scientific review aims to summarize the current knowledge about neurobiological mechanisms of cognitive impairment in people with schizophrenia, depression, mild cognitive impairment and dementia (including Alzheimer's disease).The review provides data about the prevalence of cognitive impairment in people with mental illness and associated biological markers.

Huntingtin and Its Role in Mechanisms of RNA-Mediated Toxicity

Huntington’s disease (HD) is caused by a CAG-repeat expansion mutation in the Huntingtin (HTT) gene. It is characterized by progressive psychiatric and neurological symptoms in combination with a progressive movement disorder. Despite the ubiquitous expression of HTT, pathological changes occur quite selectively in the central nervous system. Since the discovery of HD more than 150 years ago, a lot of research on molecular mechanisms contributing to neurotoxicity has remained the focal point. While traditionally, the protein encoded by the HTT gene remained the cynosure for researchers and was extensively reviewed elsewhere, several studies in the last few years clearly indicated the contribution of the mutant RNA transcript to cellular dysfunction as well. In this review, we outline recent studies on RNA-mediated molecular mechanisms that are linked to cellular dysfunction in HD models. These mechanisms include mis-splicing, aberrant translation, deregulation of the miRNA machinery, deregulated RNA transport and abnormal regulation of mitochondrial RNA. Furthermore, we summarize recent therapeutical approaches targeting the mutant HTT transcript. While currently available treatments are of a palliative nature only and do not halt the disease progression, recent clinical studies provide hope that these novel RNA-targeting strategies will lead to better therapeutic approaches.

Neurotrophic Factor BDNF, Physiological Functions and Therapeutic Potential in Depression, Neurodegeneration and Brain Cancer

Brain-derived neurotrophic factor (BDNF) is one of the most distributed and extensively studied neurotrophins in the mammalian brain. BDNF signals through the tropomycin receptor kinase B (TrkB) and the low affinity p75 neurotrophin receptor (p75NTR). BDNF plays an important role in proper growth, development, and plasticity of glutamatergic and GABAergic synapses and through modulation of neuronal differentiation, it influences serotonergic and dopaminergic neurotransmission. BDNF acts as paracrine and autocrine factor, on both pre-synaptic and post-synaptic target sites. It is crucial in the transformation of synaptic activity into long-term synaptic memories. BDNF is considered an instructive mediator of functional and structural plasticity in the central nervous system (CNS), influencing dendritic spines and, at least in the hippocampus, the adult neurogenesis. Changes in the rate of adult neurogenesis and in spine density can influence several forms of learning and memory and can contribute to depression-like behaviors. The possible roles of BDNF in neuronal plasticity highlighted in this review focus on the effect of antidepressant therapies on BDNF-mediated plasticity. Moreover, we will review data that illustrate the role of BDNF as a potent protective factor that is able to confer protection against neurodegeneration, in particular in Alzheimer’s disease. Finally, we will give evidence of how the involvement of BDNF in the pathogenesis of brain glioblastoma has emerged, thus opening new avenues for the treatment of this deadly cancer.

Differential serum exosome microRNA profile in a stress-induced depression rat model

BACKGROUND

Increasing evidence has shown the important role of exosomes in the maintenance of brain function and pathogenesis of brain disease, but little is known about their association with depression. The aim of this project was to explore the miRNA profile of exosomes in the serum of rats with depression induced by chronic unpredictable mild stress (CUMS).

METHODS

A rat model of depression was replicated via CUMS. Behavioral performance was observed, and serum exosomes were isolated and identified. The protein expression levels of brain-derived neurotrophic factor (BDNF), TrkB, and synaptotagmin 1 in the hippocampus, prefrontal cortex (PFC), and serum exosomes were measured. GO and KEGG enrichment analysis of differential genes was carried out using the R package clusterProfiler.

RESULTS

The CUMS rats showed depression-like behaviors, together with decreased expression levels of BDNF, TrkB, and synaptotagmin 1 in the hippocampus, PFC, and serum exosomes. GO and KEGG enrichment analysis indicated that the differential expression of miRNAs might play an important role in the pathogenesis of stress-induced depression through the MAPK pathway, Wnt pathway, and mTOR pathway.

LIMITATIONS

The protein expression levels of BDNF, TrkB, and synaptotagmin 1 were measured only in the hippocampus and PFC. The function of the differentially expressed miRNAs was not verified in the animal model, which should be investigated in detail in future studies.

CONCLUSIONS

The miRNA profile was altered in rats with stress-induced depression, which might be considered a potential biomarker for the early diagnosis of depression.

Antagonizing effect of icaritin on apoptosis and injury of hippocampal neurocytes induced by amyloid beta via GR/BDNF signaling pathway

Purpose: Amyloid beta is the main component of senile plaques deposited in the hippocampus of people with Alzheimer's disease (AD), with neurotoxicity and pro-apoptotic characteristics. Icaritin (ICA) has been found to have the properties of plerosis, regeneration, and anti-apoptosis in the neurocytes, its effects on Aβ-induced hippocampal neurocytes were studied in this research.Methods: Different concentrations of Aβ_25-35 were used to treat mouse hippocampal neuron HT22 cells to determine the optimal concentration for constructing AD model; different concentrations of ICA were used to pretreat HT22 cells to explore their effects on cell activity. Cell injury was evaluated by measuring the viability and apoptosis of HT22 cells using MTT assay, and Annexin V/PI and Hoechst 33342 staining, respectively. Western blot and qPCR were performed to detect the expressions of glucocorticoid receptor (GR), brain-derived neurotrophic factor (BDNF), and apoptosis-related factors. Oxidative stress was assessed by the biochemical analysis of Lactate dehydrogenase (LDH) release and superoxidase dismutase (SOD) activity.Results: Aβ_25-35 inhibited the viability of HT22 cells and the expression of GR and BDNF in HT22 cells in a concentration-dependent manner. ICA at 20 µmol/L (ICA20) the most significantly increased the viability of HT22 cells and the expressions of GR and BDNF in HT22 cells. ICA20 increased viability, inhibited apoptosis and LDH release, promoted SOD activity and the expressions of GR, BDNF and Bcl-2, and inhibited the expressions of Bax and C Caspase-3 in AD. More importantly, shRNA-GR reversed the positive effects of ICA20 on AD.Conclusions: ICA protected hippocampal neurocytes against Aβ_25-35 via GR/BDNF signaling pathway.