Down-Regulation of miRNA-30a Alleviates Cerebral Ischemic Injury Through Enhancing Beclin 1-Mediated Autophagy

Critical role of microRNAs in cellular quality control during brain aging and neurological disorders: Interplay between autophagy and proteostasis

A decline in cellular quality control mechanisms is one of the processes of brain aging. Autophagy and proteostasis are two regulatory mechanisms that maintain cellular component turnover to preserve cellular homeostasis, optimal function, and neuronal health by eliminating damaged and aggregated proteins and preventing neurodegenerative disorders (NDDs). Impaired autophagy and proteostasis are significant hallmarks of aging and many age-related NDDs. MicroRNAs are noncoding RNA molecules that have recently been shown to be essential for regulating several biological processes, such as autophagy, proteostasis, cellular differentiation, and development by targeting mRNA's 3'untranslated region (3'UTR). During brain aging, miRNAs have been shown to dysregulate proteostasis and autophagy, resulting in abnormal cellular activity and protein aggregation, a characteristic of age-related NDDs. This review highlights the complex interactions of miRNAs in the orchestration of proteostasis and autophagy. This dysregulation impairs autophagic flux and proteostasis and accelerates age-related disorders, neuroinflammation, and neurodegeneration. Understanding the complex interactions among miRNAs, autophagy, and proteostasis in the aging brain is essential for novel therapeutics development for age-related NDDs.

Targeting intracellular autophagic process for the treatment of post-stroke ischemia/reperfusion injury

Cerebral ischemia/reperfusion (I/R) injury is an important pathophysiological condition of ischemic stroke that involves a variety of physiological and pathological cell death pathways, including autophagy, apoptosis, necroptosis, and phagoptosis, among which autophagy is the most studied. We have reviewed studies published in the past 5 years regarding the association between autophagy and cerebral I/R injury. To the best of our knowledge, this is the first review article summarizing potential candidates targeting autophagic pathways in the treatment of I/R injury post ischemic stroke. The findings of this review may help to better understand the pathogenesis and mechanisms of I/R events and bridge the gap between basic and translational research that may lead to the development of novel therapeutic approaches for I/R injury.

Nattokinase's Neuroprotective Mechanisms in Ischemic Stroke: Targeting Inflammation, Oxidative Stress, and Coagulation

Aims: Nattokinase (NK), a potent serine endopeptidase, has exhibited a variety of pharmacological effects, including thrombolysis, anti-inflammation, and antioxidative stress. Building on previous research highlighting NK's promise in nerve regeneration, our study investigated whether NK exerted protective effects in transient middle cerebral artery occlusion (tMCAO)-induced cerebral ischemia-reperfusion injury and the underlying mechanisms. Results: The rats were administered NK (5000, 10000, 20000 FU/kg, i.g., 7 days before surgery, once daily). We showed that NK treatment dose dependently reduced the infarction volume and improved neurological symptoms, decreased the proinflammatory and coagulation cytokines levels, and attenuated reactive oxygen species (ROS) in the infarcted area of tMCAO rats. We also found that NK could exert neuroprotective effects in a variety of vitro models, including the microglia inflammation model and neuronal oxygen-glucose deprivation/reperfusion (OGD/R) model. Notably, NK effectively countered OGD/R-induced neuron death, modulating diverse pathways, including autophagy, apoptosis, PARP-dependent death, and endoplasmic reticulum stress. Furthermore, the neuroprotection of NK was blocked by phenylmethylsulfonyl fluoride (PMSF), a serine endopeptidase inhibitor. We revealed that heat-inactive NK was unable to protect against tMCAO injury and other vitro models, suggesting NK attenuated ischemic injury by its enzymatic activity. We conducted a proteomic analysis and found inflammation and coagulation were involved in the occurrence of tMCAO model and in the therapeutic effect of NK. Innovation and Conclusion: In conclusion, these data demonstrated that NK had multifaceted neuroprotection in ischemic brain injury, and the therapeutic effect of NK was related with serine endopeptidase activity. Antioxid. Redox Signal. 42, 228-248.

Non-coding RNAs in acute ischemic stroke: from brain to periphery

Acute ischemic stroke is a clinical emergency and a condition with high morbidity, mortality, and disability. Accurate predictive, diagnostic, and prognostic biomarkers and effective therapeutic targets for acute ischemic stroke remain undetermined. With innovations in high-throughput gene sequencing analysis, many aberrantly expressed non-coding RNAs (ncRNAs) in the brain and peripheral blood after acute ischemic stroke have been found in clinical samples and experimental models. Differentially expressed ncRNAs in the post-stroke brain were demonstrated to play vital roles in pathological processes, leading to neuroprotection or deterioration, thus ncRNAs can serve as therapeutic targets in acute ischemic stroke. Moreover, distinctly expressed ncRNAs in the peripheral blood can be used as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. In particular, ncRNAs in peripheral immune cells were recently shown to be involved in the peripheral and brain immune response after acute ischemic stroke. In this review, we consolidate the latest progress of research into the roles of ncRNAs (microRNAs, long ncRNAs, and circular RNAs) in the pathological processes of acute ischemic stroke-induced brain damage, as well as the potential of these ncRNAs to act as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. Findings from this review will provide novel ideas for the clinical application of ncRNAs in acute ischemic stroke.

MAM-mediated mitophagy and endoplasmic reticulum stress: the hidden regulators of ischemic stroke

Ischemic stroke (IS) is the predominant subtype of stroke and a leading contributor to global mortality. The mitochondrial-associated endoplasmic reticulum membrane (MAM) is a specialized region that facilitates communication between the endoplasmic reticulum and mitochondria, and has been extensively investigated in the context of neurodegenerative diseases. Nevertheless, its precise involvement in IS remains elusive. This literature review elucidates the intricate involvement of MAM in mitophagy and endoplasmic reticulum stress during IS. PINK1, FUNDC1, Beclin1, and Mfn2 are highly concentrated in the MAM and play a crucial role in regulating mitochondrial autophagy. GRP78, IRE1, PERK, and Sig-1R participate in the unfolded protein response (UPR) within the MAM, regulating endoplasmic reticulum stress during IS. Hence, the diverse molecules on MAM operate independently and interact with each other, collectively contributing to the pathogenesis of IS as the covert orchestrator.

Simvastatin exerts neuroprotective effects post-stroke by ameliorating endoplasmic reticulum stress and regulating autophagy/apoptosis balance through pAMPK/LC3B/ LAMP2 axis

Statins have evident neuroprotective role in acute ischemic stroke(AIS). The pleiotropic effect by which statin exerts neuroprotective effects, needs to be explored for considering it as one of the future adjunctive therapies in AIS. Endoplasmic reticulum(ER) assists cellular survival by reducing protein aggregates during ischemic conditions. ER-stress mediated apoptosis and autophagy are predominant reasons for neuronal death in AIS. Statin exerts both anti-apoptotic and anti-autophagic effect in neurons under ischemic stress. Although the influence of statin on autophagic neuroprotection has been reported with contradictory results. Thus, in our study we have attempted to understand its influence on autophagic protection while inhibiting upregulation of autophagic death(autosis). Previously we reported, statin can alleviate apoptosis via modulating cardiolipin mediated mitochondrial dysfunction. However, the clearance of damaged mitochondria is essential for prolonged cell survival. In our study, we tried to decipher the mechanism by which statin leads to neuronal survival by the mitophagy mediated cellular clearance. Simvastatin was administered to Sprague Dawley(SD) rats both as prophylaxis and treatment. The safety and efficacy of the statin was validated by assessment of infarct size and functional outcome. A reduction in oxidative and ER-stress were observed in both the prophylactic and treatment groups. The influence of statin on autophagy/apoptosis balance was evaluated by molecular assessment of mitophagy and cellular apoptosis. Statin reduces the post-stroke ER-stress and predominantly upregulated autophagolysosome mediated mitophagy than apoptotic cell death by modulating pAMPK/LC3B/LAMP2 axis. Based on the above findings statin could be explored as an adjunctive therapy for AIS in future.

Study on the mechanism of miR-7562 regulating ATG5 and ATG12 genes in Penaeus monodon under Vibrio harveyi infection

MicroRNAs (miRNAs) play a fundamental role in the post-transcriptional regulation of genes and are pivotal in modulating immune responses in marine species, particularly during pathogen assaults. This study focused on the function of miR-7562 and its regulatory effects on autophagy against Vibrio harveyi infection in the black tiger shrimp (Penaeus monodon), an economically important aquatic species. We successfully cloned and characterized two essential autophagy-related genes (ATGs) from P. monodon, PmATG5 and PmATG12, and then identified the miRNAs potentially involved in co-regulating these genes, which were notably miR-7562, miR-8485, and miR-278. Subsequent bacterial challenge experiments and dual-luciferase reporter assays identified miR-7562 as the principal regulator of both genes, particularly by targeting the 3'UTR of each gene. By manipulating the in vivo levels of miR-7562 using mimics and antagomirs, we found significant differences in the expression of PmATG5 and PmATG12, which corresponded to alterations in autophagic activity. Notably, miR-7562 overexpression resulted in the downregulation of PmATG5 and PmATG12, leading to a subdued autophagic response. Conversely, miR-7562 knockdown elevated the expression levels of these genes, thereby enhancing autophagic activity. Our findings further revealed that during V. harveyi infection, miR-7562 continued to influence the autophagic pathway by specifically targeting the ATG5-ATG12 complex. This research not only sheds light on the miRNA-dependent mechanisms governing autophagic immunity in shrimp but also proposes miR-7562 as a promising target for therapeutic strategies intended to strengthen disease resistance within the crustacean aquaculture industry.

Spinal Cord Injury: From MicroRNAs to Exosomal MicroRNAs

Spinal cord injury (SCI) is an unfortunate experience that may generate extensive sensory and motor disabilities due to the destruction and passing of nerve cells. MicroRNAs are small RNA molecules that do not code for proteins but instead serve to regulate protein synthesis by targeting messenger RNA's expression. After SCI, secondary damage like apoptosis, oxidative stress, inflammation, and autophagy occurs, and differentially expressed microRNAs show a function in these procedures. Almost all animal and plant cells release exosomes, which are sophisticated formations of lipid membranes. These exosomes have the capacity to deliver significant materials, such as proteins, RNAs and lipids, to cells in need, regulating their functions and serving as a way of communication. This new method offers a fresh approach to treating spinal cord injury. Obviously, the exosome has the benefit of conveying the transported material across performing regulatory activities and the blood-brain barrier. Among the exosome cargoes, microRNAs, which modulate their mRNA targets, show considerable promise in the pathogenic diagnosis, process, and therapy of SCI. Herein, we describe the roles of microRNAs in SCI. Furthermore, we emphasize the importance of exosomal microRNAs in this disease.

Therapeutic Potential of Hydrogen Sulfide in Ischemia and Reperfusion Injury

Ischemia-reperfusion (I/R) injury, a prevalent pathological condition in medical practice, presents significant treatment challenges. Hydrogen sulfide (H2S), acknowledged as the third gas signaling molecule, profoundly impacts various physiological and pathophysiological processes. Extensive research has demonstrated that H2S can mitigate I/R damage across multiple organs and tissues. This review investigates the protective effects of H2S in preventing I/R damage in the heart, brain, liver, kidney, intestines, lungs, stomach, spinal cord, testes, eyes, and other tissues. H2S provides protection against I/R damage by alleviating inflammation and endoplasmic reticulum stress; inhibiting apoptosis, oxidative stress, and mitochondrial autophagy and dysfunction; and regulating microRNAs. Significant advancements in understanding the mechanisms by which H2S reduces I/R damage have led to the development and synthesis of H2S-releasing agents such as diallyl trisulfide-loaded mesoporous silica nanoparticles (DATS-MSN), AP39, zofenopril, and ATB-344, offering a new therapeutic avenue for I/R injury.

Silencing of LINC00707 Alleviates Brain Injury by Targeting miR-30a-5p to Regulate Microglia Inflammation and Apoptosis

The role of microglia in traumatic brain injury (TBI) has gained considerable attention. The present study aims to elucidate the potential mechanisms of Long intergenic non-protein coding RNA 707 (LINC00707) in TBI-induced microglia activation and inflammatory factor release. An in vivo model of rat TBI and in vitro microglia model was established using Controlled cortex injury (CCI) and lipopolysaccharide (LPS) stimulation. RT-qPCR to detect LINC00707 levels in rat cerebral cortex or cells. Modified Neurological Impairment Score (mNSS) and Morris Water Maze test was conducted to assess the neurological deficits and cognitive impairment. ELISA analysis of pro-inflammatory factors levels. CCK-8 and flow cytometry for cell viability and apoptosis levels. Dual-luciferase report and RIP assay to validate the targeting relationship between LINC00707 and miR-30a-5p. LINC00707 was elevated in the TBI rat cerebral cortex and LPS-induced microglia, while miR-30a-5p was noticeably decreased (P < 0.05). Increased mNSS, cognitive dysfunction, and brain edema in TBI rats were all prominently reversed by silencing of LINC00707, but this reversal was partially abrogated by decreasing miR-30a-5p (P < 0.05). Inhibition of LINC00707 suppressed the overproduction of inflammatory factors in TBI rats (P < 0.05). LPS decreased microglial cell viability, increased apoptosis, and promoted inflammatory overproduction than control, but the silencing of LINC00707 reversed its effect. Suppression of miR-30a-5p attenuated this reversal (P < 0.05). miR-30a-5p was the target miRNA of LINC00707. All in all, the results suggested that inhibiting LINC00707/miR-30a-5p axis could alleviate the progression of TBI by suppressing the inflammation and apoptosis of microglia cells.

MicroRNA Profiles in Critically Ill Patients

The use of biomarkers to expedite diagnosis, prognostication, and treatment could significantly improve patient outcomes. The early diagnosis and treatment of critical illnesses can greatly reduce mortality and morbidity. Therefore, there is great interest in the discovery of biomarkers for critical illnesses. Micro-ribonucleic acids (miRNAs) are a highly conserved group of non-coding RNA molecules. They regulate the expression of genes involved in several developmental, physiological, and pathological processes. The characteristics of miRNAs suggest that they could be versatile biomarkers. Assay panels to measure the expression of several miRNAs could facilitate clinical decision-- making for a range of diseases. We have, in this paper, reviewed the current understanding of the role of miRNAs as biomarkers in critically ill patients.

TSPO exacerbates acute cerebral ischemia/reperfusion injury by inducing autophagy dysfunction

Autophagy is considered a double-edged sword, with a role in the regulation of the pathophysiological processes of the central nervous system (CNS) after cerebral ischemia-reperfusion injury (CIRI). The 18-kDa translocator protein (TSPO) is a highly conserved protein, with its expression level in the nervous system closely associated with the regulation of pathophysiological processes. In addition, the ligand of TSPO reduces neuroinflammation in brain diseases, but the potential role of TSPO in CIRI is largely undiscovered. On this basis, we investigated whether TSPO regulates neuroinflammatory response by affecting autophagy in microglia. In our study, increased expression of TSPO was detected in rat brain tissues with transient middle cerebral artery occlusion (tMCAO) and in BV2 microglial cells exposed to oxygen-glucose deprivation or reoxygenation (OGD/R) treatment, respectively. In addition, we confirmed that autophagy was over-activated during CIRI by increased expression of autophagy activation related proteins with Beclin-1 and LC3B, while the expression of p62 was decreased. The degradation process of autophagy was inhibited, while the expression levels of LAMP-1 and Cathepsin-D were significantly reduced. Results of confocal laser microscopy and transmission electron microscopy (TEM) indicated that autophagy flux was disordered. In contrast, inhibition of TSPO prevented autophagy over-activation both in vivo and in vitro. Interestingly, suppression of TSPO alleviated nerve cell damage by reducing reactive oxygen species (ROS) and pro-inflammatory factors, including TNF-α and IL-6 in microglia cells. In summary, these results indicated that TSPO might affect CIRI by mediating autophagy dysfunction and thus might serve as a potential target for ischemic stroke treatment.

Regulatory miRNAs in cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The desired outcome of cancer therapies is the eradication of disease. This can be achieved when therapy exposure leads to therapy-induced cancer cell death as the dominant outcome. Theoretically, a permanent therapy-induced growth arrest could also contribute to a complete response, which has the potential to lead to remission. However, preclinical models have shown that therapy-induced growth arrest is not always durable, as recovering cancer cell populations can contribute to the recurrence of cancer. Significant research efforts have been expended to develop strategies focusing on the prevention of recurrence. Recovery of cells from therapy exposure can occur as a result of several cell stress adaptations. These include cytoprotective autophagy, cellular quiescence, a reversable form of senescence, and the suppression of apoptosis and necroptosis. It is well documented that microRNAs regulate the response of cancer cells to anti-cancer therapies, making targeting microRNAs therapeutically a viable strategy to sensitization and the prevention of recovery. We propose that the use of microRNA-targeting therapies in prolonged sequence, that is, a significant period after initial therapy exposure, could reduce toxicity from the standard combination strategy, and could exploit new epigenetic states essential for cancer cells to recover from therapy exposure. In a step toward supporting this strategy, we survey the available scientific literature to identify microRNAs which could be targeted in sequence to eliminate residual cancer cell populations that were arrested as a result of therapy exposure. It is our hope that by successfully identifying microRNAs which could be targeted in sequence we can prevent disease recurrence.

Differential Expression of Vascular-Related MicroRNA in Circulating Endothelial Microvesicles in Adults With Spinal Cord Injury: A Pilot Study

Background

Spinal cord injury (SCI) is associated with an increased risk and prevalence of cardiopulmonary and cerebrovascular disease-related morbidity and mortality. The factors that initiate, promote, and accelerate vascular diseases and events in SCI are poorly understood. Clinical interest in circulating endothelial cell-derived microvesicles (EMVs) and their microRNA (miRNA) cargo has intensified due to their involvement in endothelial dysfunction, atherosclerosis, and cerebrovascular events.

Objectives

The aim of this study was to determine whether a subset of vascular-related miRNAs is differentially expressed in EMVs isolated from adults with SCI.

Methods

We assessed eight adults with tetraplegia (7 male/1 female; age: 46±4 years; time since injury: 26±5 years) and eight uninjured (6 male/2 female; age: 39±3 years). Circulating EMVs were isolated, enumerated, and collected from plasma by flow cytometry. The expression of vascular-related miRNAs in EMVs was assessed by RT-PCR.

Results

Circulating EMV levels were significantly higher (~130%) in adults with SCI compared with uninjured adults. The expression profile of miRNAs in EMVs from adults with SCI were significantly different than uninjured adults and were pathologic in nature. Expression of miR-126, miR-132, and miR-Let-7a were lower (~100-150%; p < .05), whereas miR-30a, miR-145, miR-155, and miR-216 were higher (~125-450%; p < .05) in EMVs from adults with SCI.

Conclusion

This study is the first examination of EMV miRNA cargo in adults with SCI. The cargo signature of vascular-related miRNAs studied reflects a pathogenic EMV phenotype prone to induce inflammation, atherosclerosis, and vascular dysfunction. EMVs and their miRNA cargo represent a novel biomarker of vascular risk and a potential target for intervention to alleviate vascular-related disease after SCI.

MicroRNAs in spinal cord injury: A narrative review

Spinal cord injury (SCI) is a global medical problem with high disability and mortality rates. At present, the diagnosis and treatment of SCI are still lacking. Spinal cord injury has a complex etiology, lack of diagnostic methods, poor treatment effect and other problems, which lead to the difficulty of spinal cord regeneration and repair, and poor functional recovery. Recent studies have shown that gene expression plays an important role in the regulation of SCI repair. MicroRNAs (miRNAs) are non-coding RNA molecules that target mRNA expression in order to silence, translate, or interfere with protein synthesis. Secondary damage, such as oxidative stress, apoptosis, autophagy, and inflammation, occurs after SCI, and differentially expressed miRNAs contribute to these events. This article reviews the pathophysiological mechanism of miRNAs in secondary injury after SCI, focusing on the mechanism of miRNAs in secondary neuroinflammation after SCI, so as to provide new ideas and basis for the clinical diagnosis and treatment of miRNAs in SCI. The mechanisms of miRNAs in neurological diseases may also make them potential biomarkers and therapeutic targets for spinal cord injuries.

Isoflurane Postconditioning Alleviates Ischemic Neuronal Injury Via MiR-384-5p Regulated Autophagy

The purpose of the study was to investigate the effect of isoflurane postconditioning on neuron injury in MCAO (middle cerebral artery occlusion) rats and its molecular mechanism of affecting autophagy through miR-384-5p/ATG5 (autophagy-related protein 5). HT22 cells (mouse hippocampal neuronal cell line) were exposed to 1.5% isoflurane for 30 min after OGD/R (oxygen-glucose deprivation/reoxygenation). Flow cytometry and CCK-8 kit were used to analyze changes in apoptosis and cell viability. The level of miR-384-5p was detected by qRT-PCR. Targetscan database prediction combined with dual luciferase reporter gene assay confirmed ATG5 as a target molecule downstream of miR-384-5p. In addition, western blot results confirmed that isoflurane postconditioning regulated miR-384-5p/ATG5 and significantly inhibited the expression of apoptosis-related proteins. Meanwhile, immunofluorescence staining for LC3II positivity combined with western blot results revealed that isoflurane postconditioning significantly inhibited autophagy. In vivo, MCAO induced neuronal injury for 90 min, followed by 24-h reperfusion. Isoflurane postconditioning (Iso) group underwent 1.5% isoflurane postconditioning for 60 min after reperfusion. Neurological scoring and TTC staining were used to evaluate the protective effect of isoflurane post-treatment on neurological injury, respectively. TUNEL staining and western blot results confirmed that isoflurane post-conditioning could regulate miR-384-5p and inhibit apoptosis. Immunofluorescence staining and western blot results confirmed that isoflurane post-conditioning inhibited autophagy in MCAO rats. Based on the above results, we speculated that the molecular mechanism of isoflurane post-conditioning to alleviate ischemic neuronal injury may be related to the regulation of miR-384-5p/ATG5-mediated autophagy.

PUM2 aggravates the neuroinflammation and brain damage induced by ischemia-reperfusion through the SLC7A11-dependent inhibition of ferroptosis via suppressing the SIRT1

Cerebral ischemia-reperfusion (I/R) injury occurs due to the restoration of blood perfusion after cerebral ischemia, which results in the damage of the brain structures and functions. Unfortunately, currently there are no effective methods for preventing and treating it. The pumilio 2 (PUM2) is a type of RBPs that has been reported to participate in the progression of several diseases. Ferroptosis is reported to be involved in I/R injury. Whether PUM2 modulated I/R injury through regulating ferroptosis remains to be elucidated. The cerebral I/R models including animal middle cerebral artery occlusion/reperfusion (MCAO/R) model and oxygen-glucose deprivation/reperfusion (OGD/R)-induced cortical neuron injury cell model of were established and, respectively. RT-qPCR was applied for evaluating PUM2, SIRT1 and SLC7A11 expression. Western blot was employed for measuring the protein expression levels. The viability of cortical neurons was tested by MTT assay. The histological damage of the brain tissues was assessed by H&E staining. The level of PUM2 was boosted in both the brain tissues of the MCAO model and OGD/R-induced cortical neuron injury model. Silence of PUM2 alleviated MCAO-induced brain injury and decreased the death of PC12 cell exposed to OGD/R. PUM2 also aggravated the accumulation of free iron in MCAO mice and OGD/R-induced cortical neuron injury model. In addition, PUM2 suppressed SLC7A11 via inhibiting expression of SIRT1. Rescue assays unveiled that downregulation of SLC7A11 reversed PUM2 mediated neuroinflammation and brain damage induced by I/R. PUM2 aggravated I/R-induced neuroinflammation and brain damage through the SLC7A11-dependent inhibition of ferroptosis by suppressing SIRT1, highlighting the role of PUM2 in preventing or treating cerebral I/R injury.

Research progress on astrocyte autophagy in ischemic stroke

Ischemic stroke is a highly disabling and potentially fatal disease. After ischemic stroke, autophagy plays a key regulatory role as an intracellular catabolic pathway for misfolded proteins and damaged organelles. Mounting evidence indicates that astrocytes are strongly linked to the occurrence and development of cerebral ischemia. In recent years, great progress has been made in the investigation of astrocyte autophagy during ischemic stroke. This article summarizes the roles and potential mechanisms of astrocyte autophagy in ischemic stroke, briefly expounds on the crosstalk of astrocyte autophagy with pathological mechanisms and its potential protective effect on neurons, and reviews astrocytic autophagy-targeted therapeutic methods for cerebral ischemia. The broader aim of the report is to provide new perspectives and strategies for the treatment of cerebral ischemia and a reference for future research on cerebral ischemia.

Some miRNA expressions and their targets in ischemic stroke

Ischemic stroke (IS) is a global health challenge leading to life-long disabilities or the deaths of patients. IS is a complex disease where genetic and environmental factors are both concerned with the pathophysiology of the condition. Here, we aimed to investigate various microRNA (miRNA) expressions and their targets in IS. A rapid and accurate diagnosis of acute IS is important to perform appropriate treatment. Therefore, there is a need for a more rapid and simple tool to carry out an acute diagnosis of IS. miRNAs are small RNA molecules serving as precious biomarkers due to their easy detection and stability in blood samples. The present systematic review aimed to summarize previous studies investigating several miRNA expressions and their targets in IS.

Differential expression of non-coding RNAs and association with cerebral ischemic vascular disorders; diagnostic and therapeutic opportunities

BACKGROUND

Over the last few decades, research associated with the coding genome, primarily DNA and transcriptome (mRNA, rRNA, and tRNA), has changed our understanding in several aspects, including physiology, diagnostics, and therapeutics. A large proportion of the human genome that encodes proteins is essential for physiology. However, the human genome represents a significantly large proportion of non-translational, i.e., non-coding (nc) RNAs like microRNAs, siRNAs, piRNAs, lncRNAs, and circRNAs. These ncRNAs do not translate into functional proteins but are associated with several events, such as the regulation of gene expression via several mechanisms. Our understanding of ncRNAs has advanced in the last decade, such as microRNAs and siRNAs, but still, several other ncRNAs remain unexplored. The study comprehended the association of ncRNAs in cerebral ischemia.

METHODS

In this study searches utilizing multiple databases, PubMed, EMBASE, and Google Scholar were made. The literature survey was done on ncRNA including short and lncRNA associated with the onset, and progression of cerebral ischemia. The literature search was also made for the studies associated with the diagnostic and therapeutic role of ncRNAs for cerebral ischemia.

RESULTS AND DISCUSSION

Reports suggested that both short and long ncRNAs are critical players of gene expression and are hence associated with the pathophysiology of cerebral ischemia. The reports demonstrate ncRNAs precisely lncRNAs and microRNAs are not only associated with cerebral ischemia progression but also potential diagnostic and therapeutic candidates.

IN CONCLUSION

This review is certainly helpful to understand the interplay of ncRNAs in understanding gene expression profile and pathophysiology of cerebral ischemia. These ncRNAs molecules show potential for diagnostic and therapeutic development.

MicroRNA: An Emerging Predictive, Diagnostic, Prognostic and Therapeutic Strategy in Ischaemic Stroke

Stroke continues to be the third-leading cause of death and disability worldwide. The limited availability of diagnostic tools approved therapeutics and biomarkers that help monitor disease progression or predict future events remain as the major challenges in the field of stroke medicine. Hence, attempts to discover safe and efficacious therapeutics and reliable biomarkers are of paramount importance. MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. Since miRNAs also play important roles in key mechanisms associated with the pathogenesis of stroke, including energy failure, inflammation and cell death, it is possible that miRNAs may serve as reliable blood-based markers for risk prediction, diagnosis and prognosis of ischaemic stroke. Discovery of better neurological outcome and smaller cerebral infarcts in animal models of ischaemic stroke treated with miRNA agomirs or antagomirs indicate that miRNAs may also play a cerebrovascular protective role after an ischaemic stroke. Nonetheless, further evidences on the optimum time for treatment and route of administration are required before effective translation of these findings into clinical practice. Bearing these in mind, this paper reviews the current literature discussing the involvement of miRNAs in major pathologies associated with ischaemic stroke and evaluates their value as reliable biomarkers and therapeutics for ischaemic stroke.

Nicotinamide Mononucleotide Adenylyltransferase 1 Regulates Cerebral Ischemia-Induced Blood-Brain Barrier Disruption Through NAD+/SIRT1 Signaling Pathway

The molecular mechanisms of blood-brain barrier (BBB) disruption in the early stage after ischemic stroke are poorly understood. In the present study, we investigated the potential role of nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1) in ischemia-induced BBB damage using an animal middle cerebral artery occlusion (MCAO) model of ischemic stroke. Recombinant human NMNAT1 (rh-NMNAT1) was administered intranasally and Sirtuin 1 (SIRT1) siRNA was administered by intracerebroventricular injection. Our results indicate that rh-NMNAT1 reduced infarct volume, improved functional outcome, and decreased BBB permeability in mice after ischemic stroke. Furthermore, rh-NMNAT1 prevented the loss of tight junction proteins (occludin and claudin-5) and reduced cell apoptosis in ischemic microvessels. NMNAT1-mediated BBB permeability was correlated with the elevation of nicotinamide adenine dinucleotide (NAD⁺)/NADH ratio and SIRT1 level in brain microvascular endothelial cells. In addition, rh-NMNAT1 treatment significantly decreased the levels of acetylated nuclear factor-κB, acetylated p53, and matrix metalloproteinase-9 in ischemic microvessels. Moreover, the protective effects of rh-NMNAT1 could be reversed by SIRT1 siRNA. In conclusion, these findings indicate that rh-NMNAT1 protects BBB integrity after cerebral ischemia via the NAD⁺/SIRT1 signaling pathway in brain microvascular endothelial cells. NMNAT1 may be a novel potential therapeutic target for reducing BBB disruption after ischemic stroke.

Autophagy at the interface of endothelial cell homeostasis and vascular disease

Autophagy is an essential intracellular process for cellular quality control. It enables cell homeostasis through the selective degradation of harmful protein aggregates and damaged organelles. Autophagy is essential for recycling nutrients, generating energy to maintain cell viability in most tissues and during adverse conditions such as hypoxia/ischaemia. The progressive understanding of the mechanisms modulating autophagy in the vasculature has recently led numerous studies to link intact autophagic responses with endothelial cell (EC) homeostasis and function. Preserved autophagic flux within the ECs has an essential role in maintaining their physiological characteristics, whereas defective autophagy can promote endothelial pro-inflammatory and atherogenic phenotype. However, we still lack a good knowledge of the complete molecular repertoire controlling various aspects of endothelial autophagy and how this is associated with vascular diseases. Here, we provide an overview of the current state of the art of autophagy in ECs. We review the discoveries that have so far defined autophagy as an essential mechanism in vascular biology and analyse how autophagy influences ECs behaviour in vascular disease. Finally, we emphasise opportunities for compounds to regulate autophagy in ECs and discuss the challenges of exploiting them to resolve vascular disease.

Role of autophagy and transcriptome regulation in acute brain injury

Autophagy is an evolutionarily conserved intracellular system that routes distinct cytoplasmic cargo to lysosomes for degradation and recycling. Accumulating evidence highlight the mechanisms of autophagy, such as clearance of proteins, carbohydrates, lipids and damaged organelles. The critical role of autophagy in selective degradation of the transcriptome is still emerging and could shape the total proteome of the cell, and thus can regulate the homeostasis under stressful conditions. Unregulated autophagy that potentiates secondary brain damage is a key pathological features of acute CNS injuries such as stroke and traumatic brain injury. This review discussed the mutual modulation of autophagy and RNA and its significance in mediating the functional consequences of acute CNS injuries.

Effects of ischemic postconditioning and long non-coding RNAs in ischemic stroke

Stroke is a main cause of disability and death among adults in China, and acute ischemic stroke accounts for 80% of cases. The key to ischemic stroke treatment is to recanalize the blocked blood vessels. However, more than 90% of patients cannot receive effective treatment within an appropriate time, and delayed recanalization of blood vessels causes reperfusion injury. Recent research has revealed that ischemic postconditioning has a neuroprotective effect on the brain, but the mechanism has not been fully clarified. Long non-coding RNAs (lncRNAs) have previously been associated with ischemic reperfusion injury in ischemic stroke. LncRNAs regulate important cellular and molecular events through a variety of mechanisms, but a comprehensive analysis of potential lncRNAs involved in the brain protection produced by ischemic postconditioning has not been conducted. In this review, we summarize the common mechanisms of cerebral injury in ischemic stroke and the effect of ischemic postconditioning, and we describe the potential mechanisms of some lncRNAs associated with ischemic stroke.

Noncoding RNA as Diagnostic and Prognostic Biomarkers in Cerebrovascular Disease

Noncoding RNAs (ncRNAs), such as microRNAs, long noncoding RNAs, and circular RNAs, play an important role in the pathophysiology of cerebrovascular diseases (CVDs). They are effectively detectable in body fluids, potentially suggesting new biomarkers for the early detection and prognosis of CVDs. In this review, the physiological functions of circulating ncRNAs and their potential role as diagnostic and prognostic markers in patients with cerebrovascular diseases are discussed, especially in acute ischemic stroke, subarachnoid hemorrhage, and moyamoya disease.

The Regulatory Role of Non-coding RNA in Autophagy in Myocardial Ischemia-Reperfusion Injury

Following an acute myocardial infarction (AMI), thrombolysis, coronary artery bypass grafting and primary percutaneous coronary intervention (PPCI) are the best interventions to restore reperfusion and relieve the ischemic myocardium, however, the myocardial ischemia-reperfusion injury (MIRI) largely offsets the benefits of revascularization in patients. Studies have demonstrated that autophagy is one of the important mechanisms mediating the occurrence of the MIRI, while non-coding RNAs are the main regulatory factors of autophagy, which plays an important role in the autophagy-related mTOR signaling pathways and the process of autophagosome formation Therefore, non-coding RNAs may be used as novel clinical diagnostic markers and therapeutic targets in the diagnosis and treatment of the MIRI. In this review, we not only describe the effect of non-coding RNA regulation of autophagy on MIRI outcome, but also zero in on the regulation of non-coding RNA on autophagy-related mTOR signaling pathways and mitophagy. Besides, we focus on how non-coding RNAs affect the outcome of MIRI by regulating autophagy induction, formation and extension of autophagic vesicles, and the fusion of autophagosome and lysosome. In addition, we summarize all non-coding RNAs reported in MIRI that can be served as possible druggable targets, hoping to provide a new idea for the prediction and treatment of MIRI.

Long Non-coding RNAs (lncRNAs), A New Target in Stroke

Stroke has become the most disabling and the second most fatal disease in the world. It has been a top priority to reveal the pathophysiology of stroke at cellular and molecular levels. A large number of long non-coding RNAs (lncRNAs) are identified to be abnormally expressed after stroke. Here, we summarize 35 lncRNAs associated with stroke, and clarify their functions on the prognosis through signal transduction and predictive values as biomarkers. Changes in the expression of these lncRNAs mediate a wide range of pathological processes in stroke, including apoptosis, inflammation, angiogenesis, and autophagy. Based on the exploration of the functions and mechanisms of lncRNAs in stroke, more timely, accurate predictions and more effective, safer treatments for stroke could be developed.

Microwave radiation induces neuronal autophagy through miR-30a-5p/AMPKα2 signal pathway

The potential health hazards of microwaves have attracted much more attention. Our previous study found that 2856 MHz microwave radiation damaged synaptic plasticity and activated autophagy in neurons. However, the mechanisms underlying microwave-induced autophagy were still unclear. In the present study, we established neuronal damage models by exposing rat hippocampal neurons and rat adrenal pheochromocytoma (PC12) cell-derived neuron-like cells to 30 mW/cm² microwaves, which resulted in miR-30a-5p (‘miR-30a’ for short) down-regulation and autophagy activation in vivo and in vitro. Bioinformatics analysis was conducted, and Beclin1, Prkaa2, Irs1, Pik3r2, Rras2, Ddit4, Gabarapl2 and autophagy-related gene 12 (Atg12) were identified as potential downstream genes of miR-30a involved in regulating autophagy. Based on our previous findings that microwave radiation could lead to abnormal energy metabolism in neurons, Prkaa2, encoding adenosine 5′-monophosphate-activated protein kinase (AMPK) α2 (AMPKα2, an important catalytic subunit of energy sensor AMPK), was selected for further analysis. Dual-luciferase reporter assay results showed that Prkaa2 was a downstream gene of miR-30a. Moreover, microwave radiation increased the expression of AMPKα2 and the phosphorylation of AMPKα (Thr¹⁷²) both in vivo and in vitro. The transfection of PC12 cells with miR-30a mimics increased miR-30a levels, reduced AMPKα2 expression, suppressed AMPKα (Thr¹⁷²) phosphorylation, and inhibited autophagy occurrence in neuron-like cells. Importantly, miR-30a overexpression abolished microwave-activated autophagy and inhibited microwave-induced AMPKα2 up-regulation and AMPKα (Thr¹⁷²) phosphorylation. In conclusion, microwave radiation promoted the occurrence of autophagy in neurons through the miR-30a/AMPKα2 signal pathway.

Targeting the Erk1/2 and autophagy signaling easily improved the neurobalst differentiation and cognitive function after young transient forebrain ischemia compared to old gerbils

The hippocampal neurogenesis occurs constitutively throughout adulthood in mammalian species, but declines with age. In this study, we overtly found that the neuroblast proliferation and differentiation in the subgranular zone and the maturation into fully functional and integrated neurons in the granule-cell layer in young gerbils following cerebral ischemia/reperfusion was much more than those in old gerbils. The neurological function and cognitive and memory-function rehabilitation in the young gerbils improved faster than those in the old one. These results demonstrated that, during long term after cerebral ischemia/reperfusion, the ability of neurogenesis and recovery of nerve function in young animals were significantly higher than that in the old animals. We found that, after 14- and 28-day cerebral ischemia/reperfusion, the phosphorylation of MEK1/2, ERK1/2, p90RSK, and MSK1/2 protein levels in the hippocampus of young gerbils was significantly much higher than that of old gerbils. The levels of autophagy-related proteins, including Beclin-1, Atg3, Atg5, and LC3 in the hippocampus were effectively maintained and elevated at 28 days after cerebral ischemia/reperfusion in the young gerbils compared with those in the old gerbils. These results indicated that an increase or maintenance of the phosphorylation of ERK1/2 signal pathway and autophagy-related proteins was closely associated with the neuroblast proliferation and differentiation and the process of maturation into neurons. Further, we proved that neuroblast proliferation and differentiation in the dentate gyrus and cognitive function were significantly reversed in young cerebral ischemic gerbils by administering the ERK inhibitor (U0126) and autophagy inhibitor (3MA). In brief, following experimental young ischemic stroke, the long-term promotion of the neurogenesis in the young gerbil’s hippocampal dentate gyrus by upregulating the phosphorylation of ERK signaling pathway and maintaining autophagy-related protein levels, it overtly improved the neurological function and cognitive and memory function.

Specific microRNAs for Modulation of Autophagy in Spinal Cord Injury

The treatment of spinal cord injury (SCI) is currently a major challenge, with a severe lack of effective therapies for yielding meaningful improvements in function. Therefore, there is a great opportunity for the development of novel treatment strategies for SCI. The modulation of autophagy, a process by which a cell degrades and recycles unnecessary or harmful components (protein aggregates, organelles, etc.) to maintain cellular homeostasis and respond to a changing microenvironment, is thought to have potential for treating many neurodegenerative conditions, including SCI. The discovery of microRNAs (miRNAs), which are short ribonucleotide transcripts for targeting of specific messenger RNAs (mRNAs) for silencing, shows prevention of the translation of mRNAs to the corresponding proteins affecting various cellular processes, including autophagy. The number of known miRNAs and their targets continues to grow rapidly. This review article aims to explore the relationship between autophagy and SCI, specifically with the intent of identifying specific miRNAs that can be useful to modulate autophagy for neuroprotection and the improvement of functional recovery in SCI.

The dual roles of autophagy and the GPCRs-mediating autophagy signaling pathway after cerebral ischemic stroke

Ischemic stroke, caused by a lack of blood supply in brain tissues, is the third leading cause of human death and disability worldwide, and usually results in sensory and motor dysfunction, cognitive impairment, and in severe cases, even death. Autophagy is a highly conserved lysosome-dependent process in which eukaryotic cells removal misfolded proteins and damaged organelles in cytoplasm, which is critical for energy metabolism, organelle renewal, and maintenance of intracellular homeostasis. Increasing evidence suggests that autophagy plays important roles in pathophysiological mechanisms under ischemic conditions. However, there are still controversies about whether autophagy plays a neuroprotective or damaging role after ischemia. G-protein-coupled receptors (GPCRs), one of the largest protein receptor superfamilies in mammals, play crucial roles in various physiological and pathological processes. Statistics show that GPCRs are the targets of about one-fifth of drugs known in the world, predicting potential values as targets for drug research. Studies have demonstrated that nutritional deprivation can directly or indirectly activate GPCRs, mediating a series of downstream biological processes, including autophagy. It can be concluded that there are interactions between autophagy and GPCRs signaling pathway, which provides research evidence for regulating GPCRs-mediated autophagy. This review aims to systematically discuss the underlying mechanism and dual roles of autophagy in cerebral ischemia, and describe the GPCRs-mediated autophagy, hoping to probe promising therapeutic targets for ischemic stroke through in-depth exploration of the GPCRs-mediated autophagy signaling pathway.

Dexmedetomidine Restores Autophagic Flux, Modulates Associated microRNAs and the Cholinergic Anti-inflammatory Pathway upon LPS-Treatment in Rats

Infections and perioperative stress can lead to neuroinflammation, which in turn is linked to cognitive impairments such as postoperative delirium or postoperative cognitive dysfunctions. The α2-adrenoceptor agonist dexmedetomidine (DEX) prevents cognitive impairments and has organo-protective and anti-inflammatory properties. Macroautophagy (autophagy) regulates many biological processes, but its role in DEX-mediated anti-inflammation and the underlying mechanism of DEX remains largely unclear. We were interested how a pretreatment with DEX protects against lipopolysaccharide (LPS)-induced inflammation in adult male Wistar rats. We used Western blot and activity assays to study how DEX modulated autophagy- and apoptosis-associated proteins as well as molecules of the cholinergic anti-inflammatory pathway, and qPCR to analyse the expression of autophagy and inflammation-associated microRNAs (miRNA) in the spleen, cortex and hippocampus at different time points (6 h, 24 h, 7 d). We showed that a DEX pretreatment prevents LPS-induced impairments in autophagic flux and attenuates the LPS-induced increase in the apoptosis-associated protein cleaved poly(ADP-ribose)-polymerase (PARP) in the spleen. Both, DEX and LPS altered miRNA expression and molecules of the cholinergic anti-inflammatory pathway in the spleen and brain. While only a certain set of miRNAs was up- and/or downregulated by LPS in each tissue, which was prevented or attenuated by a DEX pretreatment in the spleen and hippocampus, all miRNAs were up- and/or downregulated by DEX itself - independent of whether or not they were altered by LPS. Our results indicate that the organo-protective effect of DEX may be mediated by autophagy, possibly by acting on associated miRNAs, and the cholinergic anti-inflammatory pathway. Preventive effects of DEX on LPS-induced inflammation. DEX restores the LPS-induced impairments in autophagic flux, attenuates PARP cleavage and alters molecules of the cholinergic system in the spleen. Furthermore, DEX alters and prevents LPS-induced miRNA expression changes in the spleen and brain along with LPS.

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.

Noncoding RNA crosstalk in brain health and diseases

The mammalian brain expresses several classes of noncoding RNAs (ncRNAs), including long ncRNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs). These ncRNAs play vital roles in regulating cellular processes by RNA/protein scaffolding, sponging and epigenetic modifications during the pathophysiological conditions, thereby controlling transcription and translation. Some of these functions are the result of crosstalk between ncRNAs to form a competitive endogenous RNA network. These intricately organized networks comprise lncRNA/miRNA, circRNA/miRNA, or lncRNA/miRNA/circRNA, leading to crosstalk between coding and ncRNAs through miRNAs. The miRNA response elements predominantly mediate the ncRNA crosstalk to buffer the miRNAs and thereby fine-tune and counterbalance the genomic changes and regulate neuronal plasticity, synaptogenesis and neuronal differentiation. The perturbed levels and interactions of the ncRNAs could lead to pathologic events like apoptosis and inflammation. Although the regulatory landscape of the ncRNA crosstalk is still evolving, some well-known examples such as lncRNA Malat1 sponging miR-145, circRNA CDR1as sponging miR-7, and lncRNA Cyrano and the circRNA CDR1as regulating miR-7, has been shown to affect brain function. The ability to manipulate these networks is crucial in determining the functional outcome of central nervous system (CNS) pathologies. The focus of this review is to highlights the interactions and crosstalk of these networks in regulating pathophysiologic CNS function.

Dexmedetomidine attenuates neuronal injury induced by cerebral ischemia‑reperfusion by regulating miR‑199a

As is well known, dexmedetomidine (DEX) serves a neuroprotective role in cerebral ischemia‑reperfusion (CIR) injury, and microRNA (miR)‑199a has been re‑ported to be associated with IR injury. However, the association between DEX and miR‑199a in CIR injury remains unknown. Thus, the aim of the present study was to verify whether the neuroprotective effect of DEX on cerebral ischemia‑reperfusion rats is associated with miR‑199a. A rat model of CIR was established, and the modified neurological severity score (mNSS) was evaluated. The effect of DEX on the patholog‑ical structure of the cerebral cortex in CIR rats was observed by hematoxylin and eosin and Nissl staining. Reverse transcription‑quantitative PCR was used to analyze the expression levels of miR‑199a in brain tissue following intracerebroventricular injection of miR‑199a antagomir. The co‑expression of NeuN and microtubule‑associated proteins 1A/1B light chain 3B in the cerebral cortex was analyzed by immunofluorescence staining. Western blotting and immunohistochemistry were performed to analyze the expression of autophagy‑associated proteins in the brain tissue. DEX inhibited the expression of miR‑199a, decreased the mNSS and improved pathological damage to the cerebral cortex. DEX also inhibited autophagy and expression levels of associated proteins and decreased nerve cell injury. In conclusion, DEX inhibited expression of miR‑199a and improved neurocyte injury induced by CIR.

ZFP36L2 regulates myocardial ischemia/reperfusion injury and attenuates mitochondrial fusion and fission by LncRNA PVT1

Among several leading cardiovascular disorders, ischemia–reperfusion (I/R) injury causes severe manifestations including acute heart failure and systemic dysfunction. Recently, there has been increasing evidence suggesting that alterations in mitochondrial morphology and dysfunction also play an important role in the prognosis of cardiac disorders. Long non-coding RNAs (lncRNAs) form major regulatory networks altering gene transcription and translation. While the role of lncRNAs has been extensively studied in cancer and tumor biology, their implications on mitochondrial morphology and functions remain to be elucidated. In this study, the functional roles of Zinc finger protein 36-like 2 (ZFP36L2) and lncRNA PVT1 were determined in cardiomyocytes under hypoxia/reoxygenation (H/R) injury in vitro and myocardial I/R injury in vivo. Western blot and qRT-PCR analysis were used to assess the levels of ZFP36L2, mitochondrial fission and fusion markers in the myocardial tissues and cardiomyocytes. Cardiac function was determined by immunohistochemistry, H&E staining, and echocardiogram. Ultrastructural analysis of mitochondrial fission was performed using transmission electron microscopy. The mechanistic model consisting of PVT1 with ZFP36L2 and microRNA miR-21-5p with E3 ubiquitin ligase MARCH5 was assessed by subcellular fraction, RNA pull down, FISH, and luciferase reporter assays. These results identified a novel regulatory axis involving PVT1, miR-21-5p, and MARCH5 that alters mitochondrial morphology and function during myocardial I/R injury. Using an in vivo I/R injury mouse model and in vitro cardiomyocytes H/R model, we demonstrated that ZFP36L2 directly associates with PVT1 and alters mitochondrial fission and fusion. PVT1 also interactes with miR-21-5p and suppresses its expression and activity. Furthermore, we identified MARCH5 as a modifier of miR-21-5p, and its effect on mitochondrial fission and fusion are directly proportional to PVT1 expression during H/R injury. Our findings show that manipulation of PVT1-miR-21-5p-MARCH5-mediated mitochondrial fission and fusion via ZFP36L2 may be a novel therapeutic approach to regulate myocardial I/R injury.

MicroRNA-146a inhibits autophagy to maintain the intracellular survival of Burkholderia pseudomallei by targeting LIPA

Burkholderia pseudomallei is the etiological agent of melioidosis, which is an emerging infectious disease endemic to many tropical regions. Autophagy is an intrinsic cellular process that degrades cytoplasmic components and plays an important role in protecting the host against pathogens. Like many intracellular pathogens, B. pseudomallei can evade the autophagy-dependent cellular clearance. However, the underlying mechanism remains unclear. In this study, we applied a combination of multiple assays to monitor autophagy processes and found that B. pseudomallei induced an incomplete autophagic flux and eliminate autophagy clearance in macrophages by blocking autophagosome-lysosome fusion. Based on a high-throughput microarray screening, we found that LIPA (lysosomal acid LIPAse A) was downregulated during B. pseudomallei infection. MiR-146a was then identified to be specifically upregulated upon infection with B. pseudomallei and further regulated LIPA expression by interacting with 3'UTR of LIPA. Furthermore, overexpression of miR-146a contributed to the defect of autophagic flux caused by B. pseudomallei and was beneficial for the survival of B. pseudomallei in macrophages. Therefore, our findings suggest that miR-146a inhibits autophagy via posttranscriptional suppression of LIPA expression to maintain B. pseudomallei survival in macrophages.

Exogenous Hydrogen Sulfide Plays an Important Role Through Regulating Autophagy in Ischemia/Reperfusion Injury

Ischemia/reperfusion (I/R) injury is characterized by limiting blood supply to organs, then restoring blood flow and reoxygenation. It leads to many diseases, including acute kidney injury, myocardial infarction, circulatory arrest, ischemic stroke, trauma, and sickle cell disease. Autophagy is an important and conserved cellular pathway, in which cells transfer the cytoplasmic contents to lysosomes for degradation. It plays an important role in maintaining the balance of cell synthesis, decomposition and reuse, and participates in a variety of physiological and pathological processes. Hydrogen sulfide (H₂S), along with carbon monoxide (CO) and nitric oxide (NO), is an important gas signal molecule and regulates various physiological and pathological processes. In recent years, there are many studies on the improvement of I/R injury by H₂S through regulating autophagy, but the related mechanisms are not completely clear. Therefore, we summarize the related research in the above aspects to provide theoretical reference for future in-depth research.

lncRNA C2dat2 facilitates autophagy and apoptosis via the miR-30d-5p/DDIT4/mTOR axis in cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion injury (CIRI) is an important pathophysiological process of ischemic stroke associated with various physiological and pathological processes, including autophagy and apoptosis. In this study, we examined the role and mechanism of long noncoding RNA CAMK2D-associated transcript 2 (C2dat2) in regulating CIRI in vivo and in vitro. C2dat2 up-regulation facilitated neuronal autophagy and apoptosis induced by CIRI. Mechanistically, C2dat2 acts as a competing endogenous RNA (ceRNA) to negatively regulate miR-30d-5p expression. More specifically, miR-30d-5p targeted the 3′-untranslated region of DNA damage-inducible transcript 4 (DDIT4) and silenced its target mRNA DDIT4. Additionally, C2dat2 binding with heat shock cognate 70/heat shock protein 90 blocked RNA-induced silencing complex assembly to abolish the miR-30d-5p targeting of DDIT4 and inhibited miR-30d-5p to silence its target mRNA DDIT4. Further analysis showed that C2dat2 knockdown conspicuously inhibited the up-regulation of DDIT4 and Beclin-1 levels and LC3B II/I ratio and the down-regulation of P62 and phosphorylated mammalian target of rapamycin (mTOR)/mTOR and phosphorylated-P70S6K/P70S6K ratio in Neuro-2a cells after oxygen-glucose deprivation/reoxygenation. This study first revealed that C2dat2/miR-30d-5p/DDIT4/mTOR forms a novel signaling pathway to facilitate autophagy and apoptosis induced by CIRI, contributing to the better understanding of the mechanisms of CIRI and enriching the ceRNA hypothesis in CIRI.

MicroRNA-30a regulates acute cerebral ischemia-induced blood-brain barrier damage through ZnT4/zinc pathway

The mechanism of early blood-brain barrier (BBB) disruption after stroke has been intensively studied but still not fully understood. Here, we report that microRNA-30a (miR-30a) could mediate BBB damage using both cellular and animal models of ischemic stroke. In the experiments in vitro, inhibition of miR-30a decreased BBB permeability, prevented the degradation of tight junction proteins, and reduced intracellular free zinc in endothelial cells. We found that the zinc transporter ZnT4 was a direct target of negative regulation by miR-30a, and ZnT4/zinc signaling pathway contributed significantly to miR-30a-mediated BBB damage. Consistent with these in vitro findings, treatment with miR-30a inhibitor reduced zinc accumulation, increased the expression of ZnT4, and prevented the loss of tight junction proteins in microvessels of ischemic animals. Furthermore, inhibition of miR-30a, even at 90 min post onset of middle cerebral artery occlusion, prevented BBB damage, reduced infarct volume, and ameliorated neurological deficits. Together, our findings provide novel insights into the mechanisms of cerebral ischemia-induced BBB disruption and indicate miR-30a as a regulator of BBB function that can be an effective therapeutic target for ischemic stroke.

RTN1-C mediates cerebral ischemia/reperfusion injury via modulating autophagy

It has been widely accepted that autophagic cell death exacerbates the progression of cerebral ischemia/reperfusion (I/R). Our previous study revealed that overexpression of reticulon protein 1-C (RTN1-C) is involved in cerebral I/R injury. However, the underlying mechanisms have not been studied intensively. This study was designed to evaluate the effect of RTN1-C on autophagy under cerebral I/R. Using an in vitro oxygen-glucose deprivation followed by reoxygenation and a transient middle cerebral artery occlusion model in rats, we found that the expression of RTN1-C protein was significantly upregulated. We also revealed that RTN1-C knockdown suppressed overactivated autophagy both in vivo and in vitro, as indicated by decreased expressions of autophagic proteins. The number of Beclin-1/propidium iodide-positive cells was significantly less in the LV-shRTN1-C group than in the LV-shNC group. In addition, rapamycin, an activator of autophagy, aggravated cerebral I/R injury. RTN1-C knockdown reduced brain infarct volume, improved neurological deficits, and attenuated cell vulnerability to cerebral I/R injury after rapamycin treatment. Taken together, our findings demonstrated that the modulation of autophagy from RTN1-C may play vital roles in cerebral I/R injury, providing a potential therapeutic treatment for ischemic brain injury.

LncRNA Snhg8 attenuates microglial inflammation response and blood-brain barrier damage in ischemic stroke through regulating miR-425-5p mediated SIRT1/NF-κB signaling

Increasing studies have indicated that abnormal expressed long noncoding RNAs (lncRNAs) play a vital role in ischemic stroke. Small nucleolar RNA host gene 8 (Snhg8), a member of lncRNAs, has been found to induce neuronal apoptosis in chronic cerebral ischemia models. Here, we aim to explore the function and molecular mechanism of Snhg8 in modulating microglial inflammation as well as brain microvascular endothelial cell (BMEC) damage following ischemic injury. Our data suggested that Snhg8 was low-expressed in the brain tissues of mice that underwent middle cerebral artery occlusion (MCAO) surgery and oxygen-glucose deprivation (OGD)-treated primary microglia and BMECs. Gain- or loss-of function approaches found that Snhg8 upregulation not only attenuated ischemic induced inflammatory response in microglia but also relieved BMECs injury both in vitro and in vivo. Furthermore, we conducted a bioinformatics analysis to explore the underlying mechanism of Snhg8. The results indicated that Snhg8 served as a competitive endogenous RNA by sponging miR-425-5p, which was proved to promote microglial inflammation and BMECs injury by targeting sirtuin1 (SIRT1)-mediated nuclear factor-κB (NF-κB) pathway. Overall, these results revealed that the Snhg8/miR-425-5p/SIRT1/NF-κB axis plays a critical role in the regulation of cerebral ischemia-induced microglial inflammation and brain-blood barrier damage.

The Relation of the Brain-Derived Neurotrophic Factor with MicroRNAs in Neurodegenerative Diseases and Ischemic Stroke

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that plays a crucial role in the development of the nervous system while supporting the survival of existing neurons and instigating neurogenesis. Altered levels of BDNF, both in the circulation and in the central nervous system (CNS), have been reported to be involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), multiple sclerosis (MS), and ischemic stroke. MicroRNAs (miRNAs) are a class of non-coding RNAs found in body fluids such as peripheral blood and cerebrospinal fluid. Several different miRNAs, and their target genes, are recognized to be involved in the pathophysiology of neurodegenerative and neurovascular diseases. Thus, they present as promising biomarkers and a novel treatment approach for CNS disorders. Currently, limited studies provide viable evidence of miRNA-mediated post-transcriptional regulation of BDNF. The aim of this review is to provide a comprehensive assessment of the current knowledge regarding the potential diagnostic and prognostic values of miRNAs affecting BDNF expression and its role as a CNS disorders and neurovascular disease biomarker. Moreover, a novel therapeutic approach in neurodegenerative diseases and ischemic stroke targeting miRNAs associated with BDNF will be discussed.

Crosstalk Between Autophagy and Ferroptosis and Its Putative Role in Ischemic Stroke

Autophagy is a conserved process to maintains homeostasis via the degradation of toxic cell contents, which can either promote cell survival or accelerate cellular demise. Ferroptosis is a recently discovered iron-dependent cell death pathway associated with the accumulation of lethal reactive lipid species. In the past few years, an increasing number of studies have suggested the crosstalk between autophagy and ferroptosis. Ischemic stroke is a complex brain disease regulated by several cell death pathways, including autophagy and ferroptosis. However, the potential links between autophagy and ferroptosis in ischemic stroke have not yet been explored. In this review, we briefly overview the mechanisms of ferroptosis and autophagy, as well as their possible connections in ischemic stroke. The elucidation of crosstalk between different cell death pathways may provide insight into new future ischemic stroke therapies.

Detrimental and Beneficial Effect of Autophagy and a Potential Therapeutic Target after Ischemic Stroke

Autophagy, a physiologic mechanism that promotes energy recycling and orderly degradation through self-regulated disassembly of cellular components, helps maintain homeostasis. A series of evidences suggest that autophagy is activated as a response to ischemia and has been well-characterized as a therapeutic target. However, the role of autophagy after ischemia remains controversial. Activated-autophagy can remove necrotic substances against ischemic injury to promote cell survival. On the contrary, activation of autophagy may further aggravate ischemic injury, causing cell death. Therefore, the present review will examine the current understanding of the precise mechanism and role of autophagy in ischemia and recent neuroprotective therapies on autophagy, drug therapies, and nondrug therapies, including electroacupuncture (EA).

Autophagy regulation by microRNAs: Novel insights into osteosarcoma therapy

Osteosarcoma (OS) is a kind of primary bone cancer that is considered as the leading cause of children death. Surgery and chemotherapy are considered as common treatment approaches for OS; the rate of survival for patients is almost 60-70%. Besides the used therapeutic approaches, it seems that there is a crucial need to launch new treatments for OS. In this regard, more understanding about cellular and molecular pathways involved in OS can contribute to recovery and develop new therapeutic platforms. Autophagy is a cellular machinery that digests and degrades dysfunctional proteins and organelles, so it can regulate the cell proliferation and survival. Most of the time, OS cells use autophagy to increase their survival and proliferation and to gain the ability to resist chemotherapy. Although, there are several controversial evidences on how OS cells use autophagy. A variety of cellular and molecular pathways, that is, microRNAs (miRNAs) can modulate autophagy. MiRNAs are some endogenous, approximately 22 nucleotide RNAs that have an important role in posttranscriptional regulation of mRNAs by targeting them. There are many evidences that the various miRNA expressions in OS cells are dysregulated, so it can propel a normal cell to cancerous one by influencing the cell survival, apoptosis, and autophagy, and eventually increased chemoresitance. Hence, miRNAs can be considered as new biomarkers for OS diagnosis, and according to the role of autophagy in OS progression, miRNAs can use inhibiting or promoting autophagy agents. The present review summarizes the effects of aberrant expression of miRNAs in OS diagnosis and treatment with focus on their roles in autophagy.

MicroRNAs as major regulators of the autophagy pathway

Autophagy is a cellular stress response mechanism activation of which leads to degradation of cellular components, including proteins as well as damaged organelles in lysosomes. Defects in autophagy mechanisms were associated with several pathologies (e.g. cancer, neurodegenerative diseases, and rare genetic diseases). Therefore, autophagy regulation is under strict control. Transcriptional and post-translational mechanisms that control autophagy in cells and organisms studied in detail. Recent studies introduced non-coding small RNAs, and especially microRNAs (miRNAs) in the post-translational orchestration of the autophagic activity. In this review article, we analyzed in detail the current status of autophagy-miRNA connections. Comprehensive documentation of miRNAs that were directly involved in autophagy regulation resulted in the emergence of common themes and concepts governing these complex and intricate interactions. Hence, a better and systematic understanding of these interactions reveals a central role for miRNAs in the regulation of autophagy.