Long non-coding RNA MEG3 regulates autophagy after cerebral ischemia/reperfusion injury

Long non-coding RNAs in cardiac hypertrophy and heart failure: functions, mechanisms and clinical prospects

The surge in reports describing non-coding RNAs (ncRNAs) has focused attention on their possible biological roles and effects on development and disease. ncRNAs have been touted as previously uncharacterized regulators of gene expression and cellular processes, possibly working to fine-tune these functions. The sheer number of ncRNAs identified has outpaced the capacity to characterize each molecule thoroughly and to reliably establish its clinical relevance; it has, nonetheless, created excitement about their potential as molecular targets for novel therapeutic approaches to treat human disease. In this Review, we focus on one category of ncRNAs - long non-coding RNAs - and their expression, functions and molecular mechanisms in cardiac hypertrophy and heart failure. We further discuss the prospects for this specific class of ncRNAs as novel targets for the diagnosis and treatment of these conditions.

Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases

Autophagy is a dynamic self-renovation biological process that maintains cell homeostasis and is responsible for the quality control of proteins, organelles, and energy metabolism. The E1-like ubiquitin-activating enzyme autophagy-related gene 7 (ATG7) is a critical factor that initiates classic autophagy reactions by promoting the formation and extension of autophagosome membranes. Recent studies have identified the key functions of ATG7 in regulating the cell cycle, apoptosis, and metabolism associated with the occurrence and development of multiple diseases. This review summarizes how ATG7 is precisely programmed by genetic, transcriptional, and epigenetic modifications in cells and the relationship between ATG7 and aging-related diseases.

Exosomal OIP5-AS1 attenuates cerebral ischemia-reperfusion injury by negatively regulating TXNIP protein stability and inhibiting neuronal pyroptosis

BACKGROUND

Cerebral ischemia-reperfusion injury (CIRI) can cause neuronal apoptosis and lead to irreversible brain injury. Numerous lncRNAs have been reported to play important roles in CIRI, but it is unclear whether these lncRNAs can function through exosomes.

METHODS

In this study, we utilized the middle cerebral artery occlusion/reperfusion (MCAO/R) animal model and the oxygen-glucose deprivation/ reoxygenation (OGD/R) cell model. RNA sequencing was performed to screen for differentially expressed lncRNAs in M2 microglia-derived exosomes (M2-Exos). RNA pull-down, RNA immunoprecipitation, co-immunoprecipitation and ubiquitination assays were used to explore the molecular mechanism of OIP5-AS1 in alleviating CIRI.

RESULTS

M2-Exos could alleviate nerve injury and pyroptosis after CIRI in vitro and in vivo. OIP5-AS1 was found to be significantly up-regulated in M2-Exos and down-regulated in OGD/R neurons, MCAO/R mice and ischemic stroke patients. In MCAO/R mice, OIP5-AS1 could reduce cerebral infarct size, cerebral edema and mNSS scores, and inhibit the expression levels of pyroptosis-related proteins in brain tissue. TXNIP was confirmed to be a reliable binding protein of OIP5-AS1. OIP5-AS1 overexpression significantly attenuated MCAO/R-induced upregulation of TXNIP at the protein level, but not at the mRNA level. OIP5-AS1 promoted the TXNIP degradation process and increased the ubiquitination of TXNIP. ITCH could bind to TXNIP. ITCH overexpression or knockdown did not alter the mRNA level of TXNIP, but negatively regulated TXNIP expression at the protein level. ITCH accelerated the degradation and ubiquitination of TXNIP, which could be attenuated by OIP5-AS1 knockdown. OIP5-AS1 could improve neuronal damage and inhibit neuronal pyroptosis through TXNIP.

CONCLUSIONS

M2-Exo-derived OIP5-AS1 can induce TXNIP ubiquitination and degradation by recruiting ITCH, negatively regulate TXNIP protein stability, inhibit neuronal pyroptosis, and attenuate CIRI.

Transcriptomic and bioinformatics analysis of the mechanism by which erythropoietin promotes recovery from traumatic brain injury in mice

Recent studies have found that erythropoietin promotes the recovery of neurological function after traumatic brain injury. However, the precise mechanism of action remains unclear. In this study, we induced moderate traumatic brain injury in mice by intraperitoneal injection of erythropoietin for 3 consecutive days. RNA sequencing detected a total of 4065 differentially expressed RNAs, including 1059 mRNAs, 92 microRNAs, 799 long non-coding RNAs, and 2115 circular RNAs. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses revealed that the coding and non-coding RNAs that were differentially expressed after traumatic brain injury and treatment with erythropoietin play roles in the axon guidance pathway, Wnt pathway, and MAPK pathway. Constructing competing endogenous RNA networks showed that regulatory relationship between the differentially expressed non-coding RNAs and mRNAs. Because the axon guidance pathway was repeatedly enriched, the expression of Wnt5a and Ephb6, key factors in the axonal guidance pathway, was assessed. Ephb6 expression decreased and Wnt5a expression increased after traumatic brain injury, and these effects were reversed by treatment with erythropoietin. These findings suggest that erythropoietin can promote recovery of nerve function after traumatic brain injury through the axon guidance pathway.

circ-Gucy1a2 Protects Mice from Cerebral Ischemia-Reperfusion Injury by Attenuating Neuronal Apoptosis and Mitochondrial Membrane Potential Loss

Cerebral ischemia-reperfusion (I/R) injury (CI/RI) is a severe problem in patients with cerebral ischemia. The current study explored the influences of circular (circ)-Gucy1a2 on neuronal apoptosis and mitochondrial membrane potential (MMP) in the brain tissue of CI/RI mice. Forty-eight mice were randomized into the sham group, transient middle cerebral artery occlusion (tMCAO) group, lentivirus negative control (LV-NC) group, and LV-Gucy1a2 group. Mice were first injected with lentivirus loaded with LV-Gucy1a2 or LV-NC via lateral ventricle, followed by the establishment of CI/RI models 2 weeks later. Twenty-four hours after CI/RI, the neurological impairment of mice was assessed using a 6-point scoring system. The cerebral infarct volume and brain histopathological changes were determined in CI/RI mice through histological staining. In vitro, pcDNA3.1-NC and pcDNA3.1-Gucy1a2 were transfected into mouse primary cortical neurons for 48 hours, followed by the establishment of oxygen-glucose deprivation/reoxygenation (OGD/R) models. The levels of circ-Gucy1a2 in mouse brain tissues and neurons were examined using RT-qPCR. Neuronal proliferation and apoptosis, MMP loss, and oxidative stress (OS)-related indexes in neurons were detected using CCK-8 assay, flow cytometry, JC-1 staining, and H2DFFDA staining. CI/RI mouse models and OGD/R cell models were successfully established. After CI/RI, neurons in mice were impaired and the cerebral infarction volume was increased. circ-Gucy1a2 was poorly expressed in CI/RI mouse brain tissues. Overexpression of circ-Gucy1a2 increased OGD/R-induced neuronal proliferation and mitigated apoptosis, MMP loss, and OS. Overall, circ-Gucy1a2 was down-regulated in brain tissues of CI/RI mice, and overexpression of circ-Gucy1a2 can protect mice from CI/RI.

Inhibition of ERK downregulates autophagy via mitigating mitochondrial fragmentation to protect SH-SY5Y cells from OGD/R injury

BACKGROUND

Cerebral ischemia-reperfusion injury (CIRI) is the main cause leading to high mortality and neurological disability in patients with cardiac arrest/cardiopulmonary resuscitation (CA/CPR). Our previous study found that extracellular signal-regulated kinase (ERK) activation, dynamin-related protein1 (Drp1)/Mitofusin2 (Mfn2)-dependent mitochondrial dynamics imbalance, and excessive autophagy were involved in the mechanism of nerve injury after CA/CPR. However, the specific pathological signaling pathway is still unknown. This study aimed to explore the molecular function changes of ERK-Drp1/Mfn2-autophagy signaling pathway in SH-SY5Y cell oxygen-glucose deprivation/reoxygenation (OGD/R) model, to further clarify the pathophysiological mechanism of CIRI, and to provide a new strategy for cerebral protection after CIRI.

METHODS

SH-SY5Y cells were pretreated with drugs 24 h before OGD/R. The Drp1 and Mfn2 knockdown were adopted small interfering RNAs. The overexpression of p-Drp1S616 and Mfn2 were used recombinant plasmids. The expression levels of mitochondrial dynamics proteins (p-Drp1, Drp1, Mfn2, Mfn1 and Opa1) and autophagy markers (LC3, Beclin1 and p62) were measured with the Western blotting. The mRNA levels after transfection were determined by PCR. Cell injury and viability were evaluated with released LDH activity and CCK8 assay kits. Mitochondria morphology and autophagosome were observed under transmission electron microscopy. Mitochondrial function was detected by the mitochondrial permeability transition pore assay kit. The co-expression of p-ERK, p-Drp1 and LC3 was assessed with multiple immunofluorescences. One-way analysis of variance followed by least significance difference post hoc analysis (for equal homogeneity) or Dunnett's T3 test (for unequal homogeneity) were used for statistical tests.

RESULTS

ERK inhibitor-PD98059 (PD) protects SH-SY5Y cells from OGD/R-induced injury; while ERK activator-TPA had the opposite effect. Similar to autophagy inhibitor 3-MA, PD downregulated autophagy to improve cell viability; while autophagy activator-rapamycin further aggravated cell death. PD and Drp1-knockdown synergistically attenuated OGD/R-induced Drp1 activation, mPTP opening and cell injury; overexpression of Drp1S616E or ablating Mfn2 partly abolished the protective effects of PD. Multiple immunofluorescences showed that p-ERK, p-Drp1 and LC3 were co-expressed.

CONCLUSION

Inhibition of ERK downregulates autophagy via reducing Drp1/Mfn2-dependent mitochondrial fragmentation to antagonize mitochondrial dysfunction and promotes cell survival in the SH-SY5Y cells OGD/R model. Video Abstract.

The multifaceted biology of lncR-Meg3 in cardio-cerebrovascular diseases

Cardio-cerebrovascular disease, related to high mortality and morbidity worldwide, is a type of cardiovascular or cerebrovascular dysfunction involved in various processes. Therefore, it is imperative to conduct additional research into the pathogenesis and new therapeutic targets of cardiovascular and cerebrovascular disorders. Long non-coding RNAs (lncRNAs) have multiple functions and are involved in nearly all cellular biological processes, including translation, transcription, signal transduction, and cell cycle control. LncR-Meg3 is one of them and is becoming increasingly popular. By binding proteins or directly or competitively binding miRNAs, LncR-Meg3 is involved in apoptosis, inflammation, oxidative stress, endoplasmic reticulum stress, epithelial-mesenchymal transition, and other processes. Recent research has shown that LncR-Meg3 is associated with acute myocardial infarction and can be used to diagnose this condition. This article examines the current state of knowledge regarding the expression and regulatory function of LncR-Meg3 in relation to cardiovascular and cerebrovascular diseases. The abnormal expression of LncR-Meg3 can influence neuronal cell death, inflammation, apoptosis, smooth muscle cell proliferation, etc., thereby aggravating or promoting the disease. In addition, we review the bioactive components that target lncR-Meg3 and propose some potential delivery vectors. A comprehensive and in-depth analysis of LncR-Meg3’s role in cardiovascular disease suggests that targeting LncR-Meg3 may be an alternative therapy in the near future, providing new options for slowing the progression of cardiovascular disease.

An update on the molecular mechanism and pharmacological interventions for Ischemia-reperfusion injury by regulating AMPK/mTOR signaling pathway in autophagy

AMP-activated protein kinase (5'-adenosine monophosphate-activated protein kinase, AMPK)/mammalian target of rapamycin (mTOR) is an important signaling pathway maintaining normal cell function and homeostasis in vivo. The AMPK/mTOR pathway regulates cellular proliferation, autophagy, and apoptosis. Ischemia-reperfusion injury (IRI) is secondary damage that frequently occurs clinically in various disease processes and treatments, and the exacerbated injury during tissue reperfusion increases disease-associated morbidity and mortality. IRI arises from multiple complex pathological mechanisms, among which cell autophagy is a focus of recent research and a new therapeutic target. The activation of AMPK/mTOR signaling in IRI can modulate cellular metabolism and regulate cell proliferation and immune cell differentiation by adjusting gene transcription and protein synthesis. Thus, the AMPK/mTOR signaling pathway has been intensively investigated in studies focused on IRI prevention and treatment. In recent years, AMPK/mTOR pathway-mediated autophagy has been found to play a crucial role in IRI treatment. This article aims to elaborate the action mechanisms of AMPK/mTOR signaling pathway activation in IRI and summarize the progress of AMPK/mTOR-mediated autophagy research in the field of IRI therapy.

LncRNA MEG3 activates CDH2 expression by recruitment of EP300 in valproic acid-induced autism spectrum disorder

LncRNAs partake in the biological processes contributing to development of autism spectrum disorder (ASD). The aim of the present study is to investigate the effects of lncRNA maternally expressed gene 3 (MEG3) on viability and apoptosis of hippocampal neurons from ASD rats. Rats with ASD were induced using valproic acid (VPA) with normal saline (NS) as control. We performed microarray analysis on hippocampal tissues of NS rats and ASD rats to screen the differentially expressed lncRNAs. MEG3 loss in rats alleviated the impairment of learning and memory abilities induced by VPA, and promoted neuronal viability and inhibited apoptosis. MEG3 could recruit the transcription factor E1A binding protein p300 (EP300) in the nucleus and promote the cadherin 2 (CDH2) expression. CDH2 depletion in rats ameliorated the impairment of learning and memory capacities in ASD rats. After upregulation of CDH2 in neurons with sh-MEG3, we found diminished viability and increased apoptosis in hippocampal neurons of ASD rats. Taken together, MEG3 supports activation of CDH2 via EP300, thus repressing the viability of hippocampal neurons. Therefore, MEG3 upregulation may be partially responsible for the pathogenesis of ASD.

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.

An update on the functional roles of long non‑coding RNAs in ischemic injury (Review)

Ischemic injuries result from ischemia and hypoxia in cells. Tissues and organs receive an insufficient supply of nutrients and accumulate metabolic waste, which leads to the development of inflammation, fibrosis and a series of other issues. Ischemic injuries in the brain, heart, kidneys, lungs and other organs can cause severe adverse effects. Acute renal ischemia induces acute renal failure, heart ischemia induces myocardial infarction and cerebral ischemia induces cerebrovascular accidents, leading to loss of movement, consciousness and possibly, life-threatening disabilities. Existing evidence suggests that long non-coding RNAs (lncRNAs) are regulatory sequences involved in transcription, post-transcription, epigenetic regulation and multiple physiological processes. lncRNAs have been shown to be differentially expressed following ischemic injury, with the severity of the ischemic injury being affected by the upregulation or downregulation of certain types of lncRNA. The present review article provides an extensive summary of the functional roles of lncRNAs in ischemic injury, with a focus on the brain, heart, kidneys and lungs. The present review mainly summarizes the functional roles of lncRNA MALAT1, lncRNA MEG3, lncRNA H19, lncRNA TUG1, lncRNA NEAT1, lncRNA AK139328 and lncRNA CAREL, among which lncRNA MALAT1, in particular, plays a crucial role in ischemic injury and is currently a hot research topic.