Overexpression of miR-200a protects cardiomyocytes against hypoxia-induced apoptosis by modulating the kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2 signaling axis

The mechanism of Se in regulating the proliferation and apoptosis of sheep Leydig cells through the miR-200a/NRF2 pathway

This study aimed to investigate the mechanism by which Se in regulates the proliferation and apoptosis of sheep Leydig cells via the miR-200a/NRF pathway. The cells were isolated and purified from the testes of 8-month-old sheep via a Percoll density gradient. After the cells were treated with different concentrations of Se (0, 2.0, 4.0, 6.0, and 8.0 μmol/L of Se) for 18 h, the miR-200a levels was detected. MiR-200a mimics and inhibitors were transfected into the cells, resulting in five groups (control, NC mimics, miR-200a mimics, NC inhibitor and miR-200a inhibitor). Cell viability and antioxidant status were measured via CCK8 and antioxidant assays, respectively. The abundances of pro-apoptotic (BAX, CASPASE 3 and CASPASE 8), cell cycle (P21, P27 and CDK1), and NRF2-related (NRF2, HO-1, NQO1 and KEAP1) genes were detected by real-time PCR and Western blot analysis. The results revealed that miR-200a mimics group presented greater (P < 0.05) abundances of NRF2, HO-1 and NQO1 mRNA transcripts and proteins. Compared with those both in the NC mimics and the miR-200a inhibitor groups, the activities of GSH-Px and SOD, as well as cell viability in the miR-200a mimics group were significantly greater (P < 0.05). In contrast, the ROS levels, MDA content and abundances of KEAP1, P21, P27 and apoptosis-related genes mRNA transcripts and proteins were decreased (P < 0.05). The highest (P < 0.05) miR-200a expression level was detected in the Se6.0 group. Compared with that in the Se (6.0 μmol/L) group, cell viability in the Se + miR-200a inhibitor group was lower (P < 0.05). The abundances of NRF2, HO-1 and NQO1 in the Se + miR-200a inhibitor group were lower (P < 0.05) than those in the Se (6.0 μmol/L) group but greater (P < 0.05) than those in the inhibitor group, while KEAP1 displayed the opposite trend (P < 0.05). These results indicate that Se can activate the NRF2 antioxidant signaling pathway to regulate the proliferation and apoptosis of sheep Leydig cells and that miR-200a plays a vital role in this process. The regulatory effect of Se on male reproduction and spermatogenesis may be related to the number of Leydig cells. This study aimed to provide experimental data for Se regulation of spermatogenesis.

Shear-Sensitive circRNA-LONP2 Promotes Endothelial Inflammation and Atherosclerosis by Targeting NRF2/HO1 Signaling

Hemodynamic shear stress is a frictional force that acts on vascular endothelial cells and is essential for endothelial homeostasis. Physiological laminar shear stress (LSS) suppresses endothelial inflammation and protects arteries from atherosclerosis. Herein, we screened differentially expressed circular RNAs (circRNAs) that were significantly altered in LSS-stimulated endothelial cells and found that circRNA-LONP2 was involved in modulating the flow-dependent inflammatory response. Furthermore, endothelial circRNA-LONP2 overexpression promoted endothelial inflammation and atherosclerosis in vitro and in vivo. Mechanistically, circRNA-LONP2 competitively sponged miR-200a-3p and subsequently promoted Kelch-like ECH-associated protein 1, Yes-associated protein 1, and enhancer of zeste homolog 2 expression, thereby inactivating nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling, promoting oxidative stress and endothelial inflammation, and accelerating atherosclerosis. LSS-induced down-regulation of circRNA-LONP2 suppresses endothelial inflammation, at least in part, by activating the miR-200a-3p-mediated nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway. CircRNA-LONP2 may serve as a new therapeutic target for atherosclerosis.

Nrf2 for a key member of redox regulation: A novel insight against myocardial ischemia and reperfusion injuries

Nuclear factor erythroid-2 related factor 2 (Nrf2), a nuclear transcription factor, modulates genes responsible for antioxidant responses against toxic and oxidative stress to maintain redox homeostasis and participates in varieties of cellular processes such as metabolism and inflammation during myocardial ischemia and reperfusion injuries (MIRI). The accumulation of reactive oxygen species (ROS) from damaged mitochondria, xanthine oxidase, NADPH oxidases, and inflammation contributes to depraved myocardial ischemia and reperfusion injuries. Considering that Nrf2 played crucial roles in antagonizing oxidative stress, it is reasonable to delve into the up or down-regulated molecular mechanisms of Nrf2 in the progression of MIRI to provide the possibility of new therapeutic medicine targeting Nrf2 in cardiovascular diseases. This review systematically describes the generation of ROS, the regulatory metabolisms of Nrf2 as well as several natural or synthetic compounds activating Nrf2 during MIRI, which might provide novel insights for the anti-oxidative stress and original ideas targeting Nrf2 for the prevention and treatment in cardiovascular diseases.

The Role of Epicardial Adipose Tissue-Derived MicroRNAs in the Regulation of Cardiovascular Disease: A Narrative Review

Cardiovascular diseases have been leading cause of death worldwide for many decades, and obesity has been acknowledged as a risk factor for cardiovascular diseases. In the present review, human epicardial adipose tissue-derived miRNAs reported to be differentially expressed under pathologic conditions are discussed and summarized. The results of the literature review indicate that some of the epicardial adipose tissue-derived miRNAs are believed to be cardioprotective, while some others show quite the opposite effects depending on the underlying pathologic conditions. Furthermore, they suggest that that the epicardial adipose tissue-derived miRNAs have great potential as both a diagnostic and therapeutic modality. Nevertheless, mainly due to highly limited availability of human samples, it is very difficult to make any generalized claims on a given miRNA in terms of its overall impact on the cardiovascular system. Therefore, further functional investigation of a given miRNA including, but not limited to, the study of its dose effect, off-target effects, and potential toxicity is required. We hope that this review can provide novel insights to transform our current knowledge on epicardial adipose tissue-derived miRNAs into clinically viable therapeutic strategies for preventing and treating cardiovascular diseases.

Evaluation of Fermented Turmeric Milk by Lactic Acid Bacteria to Prevent UV-Induced Oxidative Stress in Human Fibroblast Cells

The nutrition enhancement of turmeric using lactic acid bacteria (LAB) was studied. Among the 23 different LAB strains, Levilactobacillus brevis BCRC12247 was chosen due to its robustness. The fermentation of a turmeric drink from L. brevis significantly improved DPPH antioxidant activity (from 71.57% to 75.87%) and total reducing capacity (2.94 ± 0.03 mM Trolox/g dw) compared to the unfermented product. The fermented turmeric samples were subjected to liquid–liquid partition, producing four different fractions. An in vitro study was conducted by treating the fractions on human fibroblast cells (Hs68). The results indicated that hexane (Hex) and water residual (WA) samples could significantly attenuate UVA (15 J/cm2)-induced reactive oxygen species (ROS), reducing the oxidative damage from 16.99 ± 3.86 to 3.42 ± 2.53 and 3.72 ± 1.76 times, respectively. Real-time polymerase chain reaction (qPCR) results showed that Hex and WA inhibited the expression of c-jun and c-fos and lowered the mmp-1 value compared to the negative control group (by 2.72 and 2.58 times, respectively). Moreover, the expressions of Nrf2 and downstream antioxidant-related genes were significantly elevated in the Hex fraction. Therefore, fermentation using L. brevis can be an effective method to elevate the nutritional values of turmeric, protecting fibroblast cells from UVA-induced photoaging and oxidative stress.

MicroRNAs target the PI3K/Akt/p53 and the Sirt1/Nrf2 signaling pathways in doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is used as a chemotherapeutic agent in the treatment of solid tumors. Irreversible cardiotoxicity is the major limitation in the clinical use of DOX. Several microRNAs (miRNAs) with diversified functions are identified that participate in exacerbating or suppressing DOX-induced cardiac damage. The miRNAs are small noncoding regulatory RNAs that modify the expression of the native genes. Studies have demonstrated that miRNAs by modifying the expression of proteins such as PTEN, Akt, and survivin can affect DOX-induced cardiac apoptosis. Moreover, miRNAs can modulate cardiac oxidative stress in DOX treatment through the posttranscriptional regulation of Sirt1, p66shc, and Nrf2 expressions. This manuscript has reviewed the regulation of the PI3K/Akt/p53 and the Sirt1/Nrf2 pathways by miRNAs in DOX-induced cardiotoxicity.

Metformin Prevents Endothelial Dysfunction in Endometriosis through Downregulation of ET-1 and Upregulation of eNOS

This study aimed to evaluate if the treatment with metformin affects the morphologic structure, endothelial function, angiogenesis, inflammation and oxidation-responsive pathways in the heart of mice with surgically induced endometriosis. B6CBA/F1 mice (n = 37) were divided into four groups; Sham (S), Metformin (M), Endometriosis (E) and Metformin/Endometriosis (ME). The cross-sectional area of cardiomyocytes was assessed after Hematoxylin-Eosin staining and fibrosis after Picrosirius-Red staining. ET-1, nitric oxide synthases-iNOS and eNOS, and VEGF and VEGFR-2 were detected by immunofluorescence. Semi-quantification of ET-1, eNOS, VEGF, NF-kB, Ikβα and KEAP-1 was performed by Western blotting. MIR199a, MIR16-1, MIR18a, MIR20a, MIR155, MIR200a, MIR342, MIR24-1 and MIR320a were quantified by Real-Time qPCR. The interaction of endometriosis and metformin effects was assessed by a two-way ANOVA test. Compared with the other groups, M-treated mice presented a higher cross-sectional area of cardiomyocytes. Heart fibrosis increased with endometriosis. Treatment of endometriosis with metformin in the ME group downregulates ET-1 and upregulates eNOS expression comparatively with the E group. However, metformin failed to mitigate NF-kB expression significantly incremented by endometriosis. The expression of MIR199a, MIR16-1 and MIR18a decreased with endometriosis, whereas MIR20a showed an equivalent trend, altogether reducing cardioprotection. In summary, metformin diminished endometriosis-associated endothelial dysfunction but did not mitigate the increase in NF-kB expression and cardiac fibrosis in mice with endometriosis.

Neuroprotective Capability of Narcissoside in 6-OHDA-Exposed Parkinson's Disease Models through Enhancing the MiR200a/Nrf-2/GSH Axis and Mediating MAPK/Akt Associated Signaling Pathway

We assessed the antioxidant potential of narcissoside from Sambucus nigra flowers (elderflowers) in Parkinson's disease models in vitro and in vivo. The results showed that narcissoside lessened the 6-hydroxydopamine (6-OHDA)-induced increase in reactive oxygen species (ROS) and apoptosis in SH-SY5Y cells. In the 6-OHDA-exposed Caenorhabditis elegans model, narcissoside reduced degeneration of dopaminergic neurons and ROS generation, and also improved dopamine-related food-sensitive behavior and shortened lifespan. Moreover, NCS increased total glutathione (GSH) by increasing the expression of the catalytic subunit and modifier subunit of γ-glutamylcysteine ligase in cells and nematodes. Treatment with a GSH inhibitor partially abolished the anti-apoptotic ability of narcissoside. Furthermore, narcissoside diminished the 6-OHDA-induced phosphorylation of JNK and p38, while rising activities of ERK and Akt in resisting apoptosis. The antioxidant response element (ARE)-luciferase reporter activity analysis and electromobility gel shift assay showed that narcissoside promotes the transcriptional activity mediated by Nrf2. Finally, we found that narcissoside augmented the expression of miR200a, a translational inhibitor of the Nrf2 repressor protein Keap1. Downregulation of Nrf2 and miR200a by RNAi and anti-miR200a, respectively, reversed the neuroprotective ability of narcissoside. In summary, narcissoside can enhance the miR200a/Nrf2/GSH antioxidant pathway, alleviate 6-OHDA-induced apoptosis, and has the neuroprotective potential.

Hypoxic/Ischemic Inflammation, MicroRNAs and δ-Opioid Receptors: Hypoxia/Ischemia-Sensitive Versus-Insensitive Organs

Hypoxia and ischemia cause inflammatory injury and critically participate in the pathogenesis of various diseases in various organs. However, the protective strategies against hypoxic and ischemic insults are very limited in clinical settings up to date. It is of utmost importance to improve our understanding of hypoxic/ischemic (H/I) inflammation and find novel therapies for better prevention/treatment of H/I injury. Recent studies provide strong evidence that the expression of microRNAs (miRNAs), which regulate gene expression and affect H/I inflammation through post-transcriptional mechanisms, are differentially altered in response to H/I stress, while δ-opioid receptors (DOR) play a protective role against H/I insults in different organs, including both H/I-sensitive organs (e.g., brain, kidney, and heart) and H/I-insensitive organs (e.g., liver and muscle). Indeed, many studies have demonstrated the crucial role of the DOR-mediated cyto-protection against H/I injury by several molecular pathways, including NLRP3 inflammasome modulated by miRNAs. In this review, we summarize our recent studies along with those of others worldwide, and compare the effects of DOR on H/I expression of miRNAs in H/I-sensitive and -insensitive organs. The alternation in miRNA expression profiles upon DOR activation and the potential impact on inflammatory injury in different organs under normoxic and hypoxic conditions are discussed at molecular and cellular levels. More in-depth investigations into this field may provide novel clues for new protective strategies against H/I inflammation in different types of organs.

The Antioxidant Transcription Factor Nrf2 in Cardiac Ischemia-Reperfusion Injury

Nuclear factor erythroid-2 related factor 2 (Nrf2) is a transcription factor that controls cellular defense responses against toxic and oxidative stress by modulating the expression of genes involved in antioxidant response and drug detoxification. In addition to maintaining redox homeostasis, Nrf2 is also involved in various cellular processes including metabolism and inflammation. Nrf2 activity is tightly regulated at the transcriptional, post-transcriptional and post-translational levels, which allows cells to quickly respond to pathological stress. In the present review, we describe the molecular mechanisms underlying the transcriptional regulation of Nrf2. We also focus on the impact of Nrf2 in cardiac ischemia-reperfusion injury, a condition that stimulates the overproduction of reactive oxygen species. Finally, we analyze the protective effect of several natural and synthetic compounds that induce Nrf2 activation and protect against ischemia-reperfusion injury in the heart and other organs, and their potential clinical application.

Rosiglitazone Suppresses Renal Crystal Deposition by Ameliorating Tubular Injury Resulted from Oxidative Stress and Inflammatory Response via Promoting the Nrf2/HO-1 Pathway and Shifting Macrophage Polarization

Oxidative stress and inflammatory response are closely related to nephrolithiasis. This study is aimed at exploring whether rosiglitazone (ROSI), a regulator of macrophage (Mp) polarization, could reduce renal calcium oxalate (CaOx) deposition by ameliorating oxidative stress and inflammatory response. Male C57 mice were equally and randomly divided into 7 groups. Kidney sections were collected on day 5 or day 8 after treatment. Pizzolato staining and polarized light optical microscopy were used to detect crystal deposition. PAS staining and TUNEL assay were performed to assess the tubular injury and cell apoptosis, respectively. Gene expression was assessed by immunohistochemistry, immunofluorescence, ELISA, qRT-PCR, and Western blot. The reactive oxygen species (ROS) level was assessed using a fluorescence microplate and fluorescence microscope. Hydrogen peroxide (H₂O₂), malonaldehyde (MDA), and glutathione (GSH) were evaluated to determine oxidative stress. Lactic dehydrogenase (LDH) activity was examined to detect cell injury. Adhesion of CaOx monohydrate (COM) crystals to HK-2 cells was detected by crystal adhesion assay. HK-2 cell death or renal macrophage polarization was assessed by flow cytometry. In vivo, renal crystal deposition, tubular injury, crystal adhesion, cell apoptosis, oxidative stress, and inflammatory response were significantly increased in the 7-day glyoxylic acid- (Gly-) treated group but were decreased in the ROSI-treated groups, especially in the groups pretreated with ROSI. Moreover, ROSI significantly reduced renal Mp aggregation and M1Mp polarization but significantly enhanced renal M2Mp polarization. In vitro, ROSI significantly suppressed renal injury, apoptosis, and crystal adhesion of HK-2 cells and markedly shifted COM-stimulated M1Mps to M2Mps, presenting an anti-inflammatory effect. Furthermore, ROSI significantly suppressed oxidative stress by promoting the Nrf2/HO-1 pathway in HK-2 cells. These findings indicate that ROSI could ameliorate renal tubular injury that resulted from oxidative stress and inflammatory response by suppressing M1Mp polarization and promoting M2Mp polarization. Therefore, ROSI is a potential therapeutic and preventive drug for CaOx nephrolithiasis.

Lutein exerts its cardioprotective effect against the experimental model of isoprenaline-induced myocardial infarction via MIAT/miR-200a/Nrf2/TXINP pathway

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality worldwide. Lutein (LU) possesses numerous pharmacological activities, including anti-inflammatory, antioxidant, and antiapoptotic effects. This study aimed to investigate the cardioprotective potential of LU in isoprenaline (ISO)-induced MI and to explore its molecular mechanisms of action. AMI was induced by two consecutive subcutaneous doses of ISO (65 mg/kg; s.c.). The LU group was pretreated with LU (20 mg/kg; p.o.) for 30 days followed by ISO injections on Days 29 and 30. ISO group showed elevated serum creatine kinas-MB (CK-MB) and considerable electrocardiographic changes along with reduced ejection fraction compared to the normal group. LU pretreatment could decrease serum CK-MB activity, normalize QRS and QTc intervals and restore ejection fraction compared to the untreated group. The ISO group demonstrated infarcted-like lesions, which were ameliorated in the LU-pretreated group. Immunohistochemical investigation revealed upregulated cardiac troponin T (cTn T) and desmin expressions in the LU-pretreated group. LU pretreatment also enhanced cardiac thioredoxin (Trx) and glutathione (GSH) contents as well as reduced lipid peroxidation, compared to the untreated group. Importantly, LU pretreatment could downregulate long noncoding MI associated transcript (lncRNA MIAT) and thioredoxin-interacting protein (TXNIP) and augment micro RNA (miR)-200a and nuclear factor erythroid 2-related factor 2 (Nrf2) expressions compared to the ISO group. Moreover, a significant inverse correlation between MIAT and miR-200a was observed. In conclusion, this study revealed that LU could ameliorate ISO-induced MI in rats by modulating MIAT/miR-200a/Nrf2 pathway.

MicroRNAs Involved in Oxidative Stress Processes Regulating Physiological and Pathological Responses

Oxidative stress influences several physiological and pathological cellular events, including cell differentiation, excessive growth, proliferation, apoptosis, and the inflammatory response. Therefore, oxidative stress is involved in the pathogenesis of various diseases, including pulmonary fibrosis, epilepsy, hypertension, atherosclerosis, Parkinson's disease, cardiovascular disease, and Alzheimer's disease. Recent studies have shown that several microRNAs (miRNAs) are involved in developing various diseases caused by oxidative stress and that miRNAs may be helpful to determine the inflammatory characteristics of immune responses during infection and disease. This review describes the known effects of miRNAs on reactive oxygen species to induce oxidative stress and the miRNA regulatory mechanisms involved in the uncoupling of Keap1-Nrf2 complexes. Finally, we summarized the functions of miRNAs in several antioxidant genes. Understanding the crosstalk between miRNAs and oxidative stress-inducing factors during physiological and pathological cellular events may have implications for designing more effective treatments for immune diseases.

Circular RNA PVT1 silencing prevents ischemia-reperfusion injury in rat by targeting microRNA-125b and microRNA-200a

Circular RNAs (circRNAs) are essential regulators associated with many cardiac conditions, including myocardial infarction (MI). This study aimed to explore circRNA expression during MI development in an animal model and in hypoxia/reoxygenation (H/R)-treated cardiomyocytes. Microarray and real-time quantitative PCR showed that the circRNA PVT1 (circPVT1) was expressed at high levels in MI tissues and H/R-triggered cardiomyocytes. Loss-of-function assays were utilized for examining the influence of circPVT1 on cardiac function and cardiomyocyte properties. Cardiac function was measured by echocardiography at 7 d after MI. Reduced circPVT1 expression significantly decreased MI-triggered myocardial infarct size by 60% and prevented MI-triggered reductions in fractional shortening (%FS) and ejection fraction (EF%). Results of LDH, CCK-8, EdU staining, colony formation assays, and flow cytometry showed that circPVT1 silencing restored cell viability and proliferation while decreased apoptosis. Mechanistic experiments indicated that microRNAs (miR)-125b and miR-200a associated with circPVT1. We demonstrated that circPVT1 functioned as a competitive endogenous RNA (ceRNA) to sponge both miR-125b and miR-200a. Gain-of-function assays showed that miR-125b and miR-200a upregulation partially eliminated the effects of circPVT1 on cardiomyocyte properties. In addition, we found that the previously reported p53/TRAF6, SIRT7, Keap1/Nrf2, and PDCD4 pathways were regulated by the circPVT1/miR-125b/miR-200a axis. In conclusion, our study suggests that circPVT1 protects the myocardium from MI and H/R injury by preventing miR-125b- and miR-200a-mediated apoptotic signaling.

Overexpression of STAT4 under hypoxia promotes EMT through miR-200a/STAT4 signal pathway

AIMS

Previous reports have found that STAT4 is involved in the epithelial-mesenchymal transition (EMT), thereby regulating the metastasis and invasion of ovarian cancer. However, the mechanisms underlying remain unclear.

MAIN METHODS

We first established hypoxia-induced in vivo and in vitro models. The expression levels of signal transducer and activator of transcription 4 (STAT4), the markers of EMT and microRNA-200a (miR-200a) were assessed by western blot and qRT-PCR analysis, respectively. Through the bioinformatics analysis and luciferase assay, the relationship between miR-200a and SATA4 was performed. The gain- and loss-function experiments were performed to examine the role of miR-200a/STAT4 axis.

KEY FINDINGS

The results showed that the protein level of STAT4 was significantly up-regulated in our hypoxia-exposed models, and contributed to the regulating of EMT. Besides, we found STAT4 was a direct target of miR-200a. Overexpression of miR-200a repressed the expression of STAT4, and inhibited EMT progress, whereas the silencing of miR-200a promoted the STAT4-mediated EMT regulation both in vitro and in vivo.

SIGNIFICANCE

Our results provided a potential molecular mechanism by which miR-200a involved in hypoxia-induced metastasis and invasion in ovarian cancer, suggesting a possible target for the treatment of ovarian cancer.

Regulation of Nrf2 signaling pathway in heart failure: Role of extracellular vesicles and non-coding RNAs

The balance between pro- and antioxidant molecules has been established as an important driving force in the pathogenesis of cardiovascular disease. Chronic heart failure is associated with oxidative stress in the myocardium and globally. Redox balance in the heart and brain is controlled, in part, by antioxidant proteins regulated by the transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which is reduced in the heart failure state. Nrf2 can, in turn, be regulated by a variety of mechanisms including circulating microRNAs (miRNAs) encapsulated in extracellular vesicles (EVs) derived from multiple cell types in the heart. Here, we review the role of the Nrf2 and antioxidant enzyme signaling pathway in mediating redox balance in the myocardium and the brain in the heart failure state. This review focuses on Nrf2 and antioxidant protein regulation in the heart and brain by miRNA-enriched EVs in the setting of heart failure. We discuss EV-mediated intra- and inter-organ communications especially, communication between the heart and brain via an EV pathway that mediates cardiac function and sympatho-excitation in heart failure. Importantly, we speculate how engineered EVs with specific miRNAs or antagomirs may be used in a therapeutic manner in heart failure.

MiR-200a-3p Aggravates DOX-Induced Cardiotoxicity by Targeting PEG3 Through SIRT1/NF-κB Signal Pathway

Doxorubicin (DOX) is a widely used cytotoxic drug whose application is limited by its severe side effects. Little was known regarding how to offset its side effects. Therefore this study aims to explore the role of miR-200a-3p in DOX-induced cardiotoxicity and its possible mechanism. DOX-induced myocardial injury rat models were established, which were then injected with miR-200a-3p inhibitor (miR-200a-3p suppression) to observe the effects of miR-200a-3p on cell proliferation, and apoptosis. Heart function and weights of rat models were also measured. Cardiomyocytes were induced by DOX, in which PEG3 knockdown or corresponding plasmids were transfected to assess the possible effect of PEG3 on cell activity. Dual luciferase reporter assay was applied to verify the binding of PEG3 with miR-200a-3p. Elevated levels of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) and left ventricular end-diastolic pressure (LVEDP), as well as suppressed left ventricular systolic pressure (LVSP) and ± dp/dt max were showed in myocardial injury rat models. DOX induced myocardial injury and increased miR-200a-3p expression levels. miR-200a-3p inhibitor could partially attenuate DOX-induced cardiotoxicity in rat models, while PEG3 could regulate myocardial injury in DOX-treated cell models. miR-200a-3p, by targeting PEG3 through SIRT1/NF-κB signal pathway, regulated cell proliferation, inflammation and apoptosis of myocardiocytes. The results in current study demonstrated that miR-200a-3p regulates cell proliferation and apoptosis of cardiomyocytes by targeting PEG3 through SIRT1/NF-κB signal pathway. This result may provide a potential clue for the treatment of DOX-induced cardiotoxicity.

Piceatannol inhibits pyroptosis and suppresses oxLDL-induced lipid storage in macrophages by regulating miR-200a/Nrf2/GSDMD axis

As a major bioactive compound from grapes, piceatannol (PIC) has been reported to exert anti-atherosclerotic activity in various studies. Nevertheless, the mechanism underlying the effect of piceatannol against atherosclerosis (AS) is elusive. Our study identified miR-200a/Nrf2/GSDMD signaling pathway as critical mediators in the effect of piceatannol on macrophages. In the present study, we confirmed that treatment of piceatannol repressed the oxLDL-induced lipid storage in macrophages. Compared with control group, piceatannol inhibited TG storage and the activity of caspase1. It is noting that in response to oxLDL challenge, piceatannol abated the pyroptosis in RAW264.7 cells, with a decreased expression of caspase1, gasdermin D (GSDMD), IL-18, IL-1β and NLRP3. Moreover, we investigated the role of microRNA (miR)-200a/Nrf2 signaling pathway in the effect of piceatannol. The results declared that after transfection of si-miR-200a or si-Nrf2 plasmids, the effects of piceatannol on macrophages were converted, including lipid storage and pyroptosis. Importantly, si-miR-200a plasmid reduced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), indicating that miR-200a acted as an enhancer of Nrf2 in macrophages. Collectively, our findings demonstrate that piceatannol exerts anti-atherosclerotic activity on RAW264.7 cells by regulating miR-200a/Nrf2/GSDMD signaling. The present study is the first time to identify miR-200a as a candidate target in AS and declared an association between miR-200a and pyroptosis, which provides a novel therapy for the treatment of AS.

MicroRNA mediated regulation of the major redox homeostasis switch, Nrf2, and its impact on oxidative stress-induced ischemic/reperfusion injury

Ischemia/reperfusion injury (IRI) initiates from oxidative stress caused by lack of blood supply and subsequent reperfusion. It is often associated with sterile inflammation, cell death and microvascular dysfunction, which ultimately results in myocardial, cerebral and hepatic IRIs. Reportedly, deregulation of Nrf2 pathway plays a significant role in the oxidative stress-induced IRIs. Further, microRNAs (miRNAs/miRs) are proved to regulate the expression and activation of Nrf2 by targeting either the 3'-UTR or the upstream regulators of Nrf2. Additionally, compounds (crocin, ZnSO4 and ginsenoside Rg1) that modulate the levels of the Nrf2-regulating miRNAs were found to exhibit a protective effect against IRIs of different organs. Therefore, the current review briefs the impact of ischemia reperfusion (I/R) pathogenesis in various organs, role of miRNAs in the regulation of Nrf2 and the I/R protective effect of compounds that alter their expression.

Keap1-Nrf2 Pathway Regulates ALDH and Contributes to Radioresistance in Breast Cancer Stem Cells

Tumor recurrence after radiotherapy due to the presence of breast cancer stem cells (BCSCs) is a clinical challenge, and the mechanism remains unclear. Low levels of ROS and enhanced antioxidant defenses are shown to contribute to increasing radioresistance. However, the role of Nrf2-Keap1-Bach1 signaling in the radioresistance of BCSCs remains elusive. Fractionated radiation increased the percentage of the ALDH-expressing subpopulation and their sphere formation ability, promoted mesenchymal-to-epithelial transition and enhanced radioresistance in BCSCs. Radiation activated Nrf2 via Keap1 silencing and enhanced the tumor-initiating capability of BCSCs. Furthermore, knockdown of Nrf2 suppressed ALDH+ population and stem cell markers, reduced radioresistance by decreasing clonogenicity and blocked the tumorigenic ability in immunocompromised mice. An underlying mechanism of Keap1 silencing could be via miR200a, as we observed a significant increase in its expression, and the promoter methylation of Keap1 or GSK-3β did not change. Our data demonstrate that ALDH+ BCSC population contributes to breast tumor radioresistance via the Nrf2-Keap1 pathway, and targeting this cell population with miR200a could be beneficial but warrants detailed studies. Our results support the notion that Nrf2-Keap1 signaling controls mesenchymal-epithelial plasticity, regulates tumor-initiating ability and promotes the radioresistance of BCSCs.

Protective effects of natural compounds against oxidative stress in ischemic diseases and cancers via activating the Nrf2 signaling pathway: A mini review

Oxidative stress, an imbalance between reactive oxygen species and antioxidants, has been seen in the pathological states of many disorders such as ischemic diseases and cancers. Many natural compounds (NCs) have long been recognized to ameliorate oxidative stress due to their inherent antioxidant activities. The modulation of oxidative stress by NCs via activating the Nrf2 signaling pathway is summarized in the review. Three NCs, ursolic acid, betulinic acid, and curcumin, and the mechanisms of their cytoprotective effects are investigated in myocardial ischemia, cerebral ischemia, skin cancer, and prostate cancer. To promote the therapeutic performance of NCs with poor water solubility, the formulation approach, such as the nano drug delivery system, is elaborated as well in this review.

The c.*52 A/G and c.*773 A/G Genetic Variants in the UTR'3 of the LDLR Gene Are Associated with the Risk of Acute Coronary Syndrome and Lower Plasma HDL-Cholesterol Concentration

Dyslipidemia has a substantial role in the development of acute coronary syndrome (ACS). Low-density lipoprotein receptor (LDLR) plays a critical role in plasma lipoprotein hemostasis, which is involved in the formation of atherosclerotic plaque. This study aimed to evaluate whether LDLR gene polymorphisms are significantly associated with ACS and the plasma lipids profile. Three LDLR gene polymorphisms located in the UTR′3 region (c.*52 A/G, c.*504 A/G, and c.* 773 A/G) were determined using TaqMan genotyping assays in a group of 618 ACS patients and 666 healthy controls. Plasma lipids profile concentrations were determined by enzymatic/colorimetric assays. Under co-dominant and recessive models, the c.*52 A allele of the c.*52 A/G polymorphism was associated with a higher risk of ACS (OR = 2.02, pC_Co-dom = 0.033, and OR = 2.00, pC_Res = 0.009, respectively). In the same way, under co-dominant and recessive models, the c.*773 G allele of the c.*773 A/G polymorphism was associated with a high risk of ACS (OR = 2.04, pC_Co-dom = 0.027, and OR = 2.01, pC_Res = 0.007, respectively). The “AAG” haplotype was associated with a high risk of ACS (OR = 1.22, pC = 0.016). The c.*52 AA genotype showed a lower HDL-C concentration than individuals with the GG genotype. In addition, carriers of c.*773 GG genotype carriers had a lower concentration of the high-density lipoprotein-cholesterol (HDL-C) than subjects with the AA genotype. Our data suggest the association of the LDLRc.*773 A/G and LDLR c.*52 A/G polymorphisms with both the risk of developing ACS and with a lower concentration of HDL-C in the study population.

Akebia Saponin D ameliorated kidney injury and exerted anti-inflammatory and anti-apoptotic effects in diabetic nephropathy by activation of NRF2/HO-1 and inhibition of NF-KB pathway

Diabetic nephropathy (DN), a common microvascular complication of type 2 diabetes mellitus (T2DM), causes increasing mortality and morbidity due to its high prevalence and severe consequences. Hence, it is urgent to search for effective agents that provide new insights into novel molecular therapeutic targets for DN. This study was designed to investigate the critical role of Akebia saponin D (ASD) in kidney damage, inflammation and apoptosis of renal tubular cells in DN. To probe the protective effects of ASD on DN in vivo, diabetes mellitus model was established by intraperitoneal (ip) injection of STZ (60 mg/kg) for 5 days consecutively. Besides, HG-induced human renal tubular cells (HK-2) were used to analyze the defined effects and underlying mechanism of ASD on DN in vitro. Blood glucose, insulin, serum creatinine (Scr), blood urea nitrogen (BUN), renal injury, inflammation, oxidative stress and apoptosis of renal tubular cells were respectively measured and evaluated. ASD prevented kidney damage, improved renal function and inflammatory reaction, ameliorated oxidative stress and inhibited apoptosis of renal tubular cells in DN mice via activation of NRF2/HO-1 pathway and inhibition of NF-KB pathway.

Radix Angelica Sinensis and Radix Hedysari Ultrafiltration Extract Protects against X-Irradiation-Induced Cardiac Fibrosis in Rats

Radiation-induced myocardial fibrosis (RIMF) is the main pathological change associated with radiation-induced heart toxicity after radiation therapy in patients with thoracic tumors. There is an antifibrosis effect of Radix Angelica Sinensis and Radix Hedysari (RAS-RH) ultrafiltration extract from Danggui Buxue decoction (DBD) in X-irradiation-induced rat myocardial fibrosis, and this study aimed to investigate whether that effect correlated with apoptosis and oxidative stress damage in primary rat cardiac fibroblasts; further, the potential mechanisms were also explored. In this study, we first found that the RAS-RH antifibrosis effect was associated with the upregulation of microRNA-200a and the downregulation of TGF-β1/smad3 and COL1α. In addition, we also found that the antifibrosis effect of RAS-RH was related to the induction of apoptosis in primary rat cardiac fibroblasts and to the prevention of damage caused by reactive oxygen species (ROS). Interestingly, primary rat cardiac fibroblasts exposed to X-ray radiation underwent apoptosis less frequently in the absence of RAS-RH. Therefore, RAS-RH has the ability to protect against fibrosis, which could be occurring through the induction of apoptosis and the resistance to oxidative stress in rats with X-irradiation-induced myocardial fibrosis; thus, in a model of RIMF, RAS-RH acts against X-irradiation-induced cardiac toxicity.

Cardiac miRNA Expression and their mRNA Targets in a Rat Model of Prediabetes

Little is known about the mechanism of prediabetes-induced cardiac dysfunction. Therefore, we aimed to explore key molecular changes with transcriptomic and bioinformatics approaches in a prediabetes model showing heart failure with preserved ejection fraction phenotype. To induce prediabetes, Long-Evans rats were fed a high-fat diet for 21 weeks and treated with a single low-dose streptozotocin at week 4. Small RNA-sequencing, in silico microRNA (miRNA)-mRNA target prediction, Gene Ontology analysis, and target validation with qRT-PCR were performed in left ventricle samples. From the miRBase-annotated 752 mature miRNA sequences expression of 356 miRNAs was detectable. We identified two upregulated and three downregulated miRNAs in the prediabetic group. We predicted 445 mRNA targets of the five differentially expressed miRNAs and selected 11 mRNAs targeted by three differentially expressed miRNAs, out of which five mRNAs were selected for validation. Out of these five targets, downregulation of three mRNAs i.e., Juxtaposed with another zinc finger protein 1 (Jazf1); RAP2C, member of RAS oncogene family (Rap2c); and Zinc finger with KRAB and SCAN domains 1 (Zkscan1) were validated. This is the first demonstration that prediabetes alters cardiac miRNA expression profile. Predicted targets of differentially expressed miRNAs include Jazf1, Zkscan1, and Rap2c mRNAs. These transcriptomic changes may contribute to the diastolic dysfunction and may serve as drug targets.

MiR-429/200a/200b negatively regulate Notch1 signaling pathway to suppress CoCl2-induced apoptosis in PC12 cells

Neuronal apoptosis is a central hallmark of cerebral ischemia, which is serious threats to human health. Notch1 signaling pathway and three members of miR-200 family, miR-429, miR-200a and miR-200b, are reported to have tight connection with hypoxia-induced injury. However, their mutual regulation relationship and their roles in neuronal apoptosis caused by hypoxia are rarely reported. In the present study, differentiated pheochromocytoma (PC12) cells were treated with chemical hypoxia inducer, cobalt chloride (CoCl₂) to establish in vitro neuronal hypoxia model. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, Western blot assay and Hoechst staining indicated that CoCl₂ caused apoptosis of PC12 cells along with the activation of Notch1 signallilng pathway. The treatment of N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butylester (DAPT) inhibited Notch1 signaling pathway and attenuated the apoptosis induced by CoCl₂. Real-time polymerase chain reaction (RT-PCR) showed that expressions of miR-429/200a/200b were dynamically changed during the treatment of CoCl₂, and significantly decreased after 12-hour treatment of CoCl₂. Overexpression of miR-429/200a/200b inhibited the Notch1 signaling pathway and suppressed CoCl₂-induced apoptosis in PC12 cells. These results may clarify the roles of miR-429/200a/200b and Notch1 signaling pathway in hypoxia-induced nerve injury and provide a new theoretical basis to relieve nerve injury.

Akebia Saponin D suppresses inflammation in chondrocytes via the NRF2/HO-1/NF-κB axis and ameliorates osteoarthritis in mice

Akebia Saponin D promotes the translocation of NRF2 into nucleus, activates NRF2/HO-1 pathway and inhibits NF-κB pathway in chondrocytes, and ultimately alleviates osteoarthritis development.

Targets and mechanisms of sulforaphane derivatives obtained from cruciferous plants with special focus on breast cancer - contradictory effects and future perspectives

Breast cancer is the most common type of cancer among women. Therefore, discovery of new and effective drugs with fewer side effects is necessary to treat it. Sulforaphane (SFN) is an organosulfur compound obtained from cruciferous plants, such as broccoli and mustard, and it has the potential to treat breast cancer. Hence, it is vital to find out how SFN targets certain genes and cellular pathways in treating breast cancer. In this review, molecular targets and cellular pathways of SFN are described. Studies have shown SFN inhibits cell proliferation, causes apoptosis, stops cell cycle and has anti-oxidant activities. Increasing reactive oxygen species (ROS) produces oxidative stress, activates inflammatory transcription factors, and these result in inflammation leading to cancer. Increasing anti-oxidant potential of cells and discovering new targets to reduce ROS creation reduces oxidative stress and it eventually reduces cancer risks. In short, SFN effectively affects histone deacetylases involved in chromatin remodeling, gene expression, and Nrf2 anti-oxidant signaling. This review points to the potential of SFN to treat breast cancer as well as the importance of other new cruciferous compounds, derived from and isolated from mustard, to target Keap1 and Akt, two key regulators of cellular homeostasis.

Exosomes in ischemic heart disease: novel carriers for bioinformation

The occurrence of ischemic heart disease(IHD) is a multi-step chain process from potential risk factors to overt clinical diseases. Vascular cells, blood cells, cardiomyocytes and stem cells are all involved in the pathophysiological links via continual and polynary crosstalk. Exosomes,as powerful vectors for intercellular communication,have been a hotspot for basic and clinical research. Plenty of evidence has shown that exosomes largely participate in the evolution of IHD, including endothelial dysfunction, lipid deposition, atheromatous plaque formation and rupture, myocardial ischemia-reperfusion(I/R) injury,and heart failure (HF), while the rules for detailed communication in the different stages of this continuous disease are still poorly understood. This review will systematically describe characteristics of exosomal crosstalk between different cells in the diverse periods, and also cast light on the potential and challenges for exosome application as therapeutic targets, hoping to offer supporting background for the following research.

Long Noncoding RNA MALAT1 Regulates Hepatocellular Carcinoma Growth Under Hypoxia via Sponging MicroRNA-200a

PURPOSE

Hepatocellular carcinoma (HCC) is a common cancer worldwide. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long noncoding RNA (lncRNA), has been reported to be aberrantly expressed in hypoxic cancer cells. MALAT1 plays a significant role in many malignancies, including HCC. The aim of this study was to explore the role of MALAT1 in hypoxic HCC cells and its underlying regulatory mechanism.

MATERIALS AND METHODS

Quantitative reverse transcription PCR (qRT-PCR) assay was performed to detect the mRNA levels of MALAT1 and microRNA-200a (miR-200a) in HCC cells. Cell invasion and migration ability were evaluated by Transwell assay. Starbase v2.0 and luciferase reporter assay were employed to identify the association between MALAT1 and miR-200a. Cell proliferation and apoptosis were measured by MTT assay and flow cytometry, respectively.

RESULTS

MALAT1 levels were significantly upregulated in HCC cells under hypoxia. Hypoxia promoted proliferation, migration, and invasion, and blocked apoptosis in Hep3B cells, which were weakened by knockdown of MALAT1. Starbase v2.0 showed that MALAT1 and miR-200a have a complementarity region, and luciferase reporter assay verified that MALAT1 interacted with miR-200a in Hep3B cells. Moreover, MALAT1 negatively regulated the expression of miR-200a. miR-200a levels were dramatically downregulated in HCC cells under hypoxia. Upregulation of miR-200a inhibited proliferation, migration, and invasion, and induced apoptosis in Hep3B cells under hypoxia. Interestingly, downregulation of miR-200a partially reversed the tumor-suppressive effect of knockdown of MALAT1 on Hep3B cells in hypoxic condition.

CONCLUSION

LncRNA MALAT1 was involved in proliferation, migration, invasion, and apoptosis by interacting with miR-200a in hypoxic Hep3B cells, revealing a new mechanism of MALAT1 involved in hypoxic HCC progression.

miR-200a mediates protection of thymosin β-4 in cardiac microvascular endothelial cells as a novel mechanism under hypoxia-reoxygenation injury

Thymosin β-4 (Tβ4) is a ubiquitous protein, which has been suggested to regulate multiple cell signal pathways and a variety of cellular functions. However, the role Tβ4 plays in the cardiac microvascular endothelial cells (CMECs) under myocardial ischemia/reperfusion injury is currently unknown. Here we investigated the effects of Tβ4 on hypoxia/reoxygenation (H/R) induced CMECs injury and its potential molecular mechanism. Cultured CMECs were positively identified by flow cytometry using antibody against CD31 and VWF/Factor VIII, which are constitutively expressed on the surface of CMECs. Then the reduced level of Tβ4 was detected in H/R-CMECs by a real-time quantitative polymerase chain reaction. To determine the effects of Tβ4 on H/R-CMECs, we transfected the overexpression or silence vector of Tβ4 into CMECs under H/R condition. Our results indicated that H/R treatment could reduce proliferation, increased apoptosis, adhesion, and reactive oxygen species (ROS) production in CMECs, which were attenuated by Tβ4 overexpression or aggravated by Tβ4 silencing, implying Tβ4 is able to promote CMECs against H/R-induced cell injury. Furthermore, the microRNA-200a (miR-200a) level was also increased by Tβ4 in H/R-CMECs or reduced by Tβ4 small interfering RNA. To investigated the mechanism of protective effects of Tβ4 on CMECs injury, the miR-200a inhibitor was transfected into H/R-CMECs. The results indicated that inhibition of miR-200a inversed the protection of Tβ4 on H/R-CMECs, specifically including cell proliferation, cell adhesion, cell apoptosis, and ROS production, as well as nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation. In conclusion, our results determined that Tβ4 attenuated H/R-induced CMECs injury by miR-200a-Nrf2 signaling.

Aging, Melatonin, and the Pro- and Anti-Inflammatory Networks

Aging and various age-related diseases are associated with reductions in melatonin secretion, proinflammatory changes in the immune system, a deteriorating circadian system, and reductions in sirtuin-1 (SIRT1) activity. In non-tumor cells, several effects of melatonin are abolished by inhibiting SIRT1, indicating mediation by SIRT1. Melatonin is, in addition to its circadian and antioxidant roles, an immune stimulatory agent. However, it can act as either a pro- or anti-inflammatory regulator in a context-dependent way. Melatonin can stimulate the release of proinflammatory cytokines and other mediators, but also, under different conditions, it can suppress inflammation-promoting processes such as NO release, activation of cyclooxygenase-2, inflammasome NLRP3, gasdermin D, toll-like receptor-4 and mTOR signaling, and cytokine release by SASP (senescence-associated secretory phenotype), and amyloid-β toxicity. It also activates processes in an anti-inflammatory network, in which SIRT1 activation, upregulation of Nrf2 and downregulation of NF-κB, and release of the anti-inflammatory cytokines IL-4 and IL-10 are involved. A perhaps crucial action may be the promotion of macrophage or microglia polarization in favor of the anti-inflammatory phenotype M2. In addition, many factors of the pro- and anti-inflammatory networks are subject to regulation by microRNAs that either target mRNAs of the respective factors or upregulate them by targeting mRNAs of their inhibitor proteins.

MicroRNA-503 regulates hypoxia-induced cardiomyocytes apoptosis through PI3K/Akt pathway by targeting IGF-1R

Coronary heart disease is the second highest specific cause of death. H9c2 cardiomyocytes were subjected to hypoxia (1% O₂) for 0, 6, 12, 24 and 48 h. Cell apoptosis and the activity of caspase3/7 was detected using ELISA; western blot was applied to determine the cleaved-caspase3 (c-caspase3), cleaved-PARP (c-PARP) and cytochrome C (Cyto C) expression after the inhibitor negative control (in-NC), miR-503 inhibitor, mimic negative control (mi-NC) and miR-503 mimic were transfected into cells for 48 h. Moreover, flow cytometry was applied to evaluate mitochondrial membrane potential. In addition, luciferase reporter gene assay was used for detection the relationship between miR-503 and insulin-like growth-factor-1 receptor (IGF-1R). Real-time PCR showed microRNA-503 (miR-503) was elevated in a time-dependent manner under hypoxia. MiR-503 inhibition prevented cell apoptosis and reduced caspase3/7 activity and the expression of c-caspase3 and c-PARP, prevented mitochondrial membrane potential collapse and reduced the cyto C level in cytosol. While, miR-503 overexpression showed a pro-apoptotic role and resulted in mitochondrial membrane potential loss. MiR-503 directly targets IGF-1R in H9c2 cardiomyocytes. The depletion of IGF-1R using a specific IGF-1R siRNA (siIGF-1R) abolished anti-apoptotic function of miR-503 inhibitor, and LY294002 showed a similar trend. In summary, miR-503 promoted cell apoptosis, caused mitochondrial membrane potential collapse and the emancipation of cyto C from mitochondrial through PI3K/Akt pathway via targeting IGF-1R in H9c2 cardiomyocytes.

Nrf2: Molecular and epigenetic regulation during aging

Increase in life-span is commonly related with age-related diseases and with gradual loss of genomic, proteomic and metabolic integrity. Nrf2 (Nuclear factor-erythroid 2-p45 derived factor 2) controls the expression of genes whose products include antioxidant proteins, detoxifying enzymes, drug transporters and numerous cytoprotective proteins. Several experimental approaches have evaluated the potential regulation of the transcription factor Nrf2 to enhance the expression of genes that contend against accumulative oxidative stress and promote healthy aging. Negative regulators of Nrf2 that act preventing it´s binding to DNA-responsive elements, have been identified in young and adult animal models. However, it is not clearly established if Nrf2 decreased activity in several models of aging results from disruption of that regulation. In this review, we present a compilation of evidences showing that changes in the levels or activity of Keap1 (Kelch-like ECH associated protein 1), GSK-3β (glycogen synthase kinase-3), Bach1, p53, Hrd1 (E3 ubiquitin ligase) and miRNAs might impact on Nrf2 activity during elderly. We conclude that understanding Nrf2 regulatory mechanisms is essential to develop a rational strategy to prevent the loss of cellular protection response during aging.

Polydatin prevents fructose-induced liver inflammation and lipid deposition through increasing miR-200a to regulate Keap1/Nrf2 pathway

Oxidative stress is a critical factor in nonalcoholic fatty liver disease pathogenesis. MicroRNA-200a (miR-200a) is reported to target Kelch-like ECH-associated protein 1 (Keap1), which regulates nuclear factor erythroid 2-related factor 2 (Nrf2) anti-oxidant pathway. Polydatin (3,4',5-trihydroxy-stilbene-3-β-D-glucoside), a polyphenol found in the rhizome of Polygonum cuspidatum, have anti-oxidative, anti-inflammatory and anti-hyperlipidemic effects. However, whether miR-200a controls Keap1/Nrf2 pathway in fructose-induced liver inflammation and lipid deposition and the blockade of polydatin are still not clear. Here, we detected miR-200a down-regulation, Keap1 up-regulation, Nrf2 antioxidant pathway inactivation, ROS-driven thioredoxin-interacting protein (TXNIP) over-expression, NOD-like receptor (NLR) family, pyrin domain containing 3 (NLRP3) inflammasome activation and dysregulation of peroxisome proliferator activated receptor-α (PPAR-α), carnitine palmitoyl transferase-1 (CPT-1), sterol regulatory element binging protein 1 (SREBP-1) and stearoyl-CoA desaturase-1 (SCD-1) in rat livers, BRL-3A and HepG2 cells under high fructose induction. Furthermore, the data from the treatment or transfection of miR-200a minic, Keap1 and TXNIP siRNA, Nrf2 activator and ROS inhibitor demonstrated that fructose-induced miR-200a low-expression increased Keap1 to block Nrf2 antioxidant pathway, and then enhanced ROS-driven TXNIP to activate NLRP3 inflammasome and disturb lipid metabolism-related proteins, causing inflammation and lipid deposition in BRL-3A cells. We also found that polydatin up-regulated miR-200a to inhibit Keap1 and activate Nrf2 antioxidant pathway, resulting in attenuation of these disturbances in these animal and cell models. These findings provide a novel pathological mechanism of fructose-induced redox status imbalance and suggest that the enhancement of miR-200a to control Keap1/Nrf2 pathway by polydatin is a therapeutic strategy for fructose-associated liver inflammation and lipid deposition.

lncRNA KRAL reverses 5-fluorouracil resistance in hepatocellular carcinoma cells by acting as a ceRNA against miR-141

Background

5-Fluorouracil (5-FU) has been widely applied to treat various types of cancers, including hepatocellular carcinoma (HCC). However, primary or acquired 5-FU resistance prevents the clinical application of this drug in cancer therapy. Herein, our study is the first to demonstrate that lower expression of KRAL, a long non-coding RNA (lncRNA), mediates 5-FU resistance in HCC via the miR-141/Keap1 axis.

Methods

Cell proliferation assays, western blot analysis, qRT-PCR, the dual-luciferase reporter assay and RNA immunoprecipitation were performed to investigate the mechanisms by which KRAL mediates 5-fluorouracil resistance in HCC cell lines.

Results

The quantitative analysis indicated that KRAL and Keap1 were significantly decreased and that Nrf2 was increased in HepG2/5-FU and SMMC-7721/5-FU cells compared with the corresponding expression levels in the respective parental cells. Overexpression of KRAL increased Keap1 expression, and inactivating the Nrf2-dependent antioxidant pathway could reverse the resistance of HepG2/5-FU and SMMC-7721/5-FU cells to 5-FU. Moreover, KRAL functioned as a competitive endogenous RNA (ceRNA) by effectively binding to the common miR-141 and then restoring Keap1 expression. These findings demonstrated that KRAL is an important regulator of Keap1; furthermore, the ceRNA network involving KRAL may serve as a treatment strategy against 5-FU resistance in hepatocellular carcinoma cells.

Conclusions

KRAL/miR-141/Keap1 axis mediates 5-fluorouracil resistance in HCC cell lines.

Need (more than) two to Tango: Multiple tools to adapt to changes in oxygen availability

Oxygen is a fundamental element for the life of a large number of living organisms allowing an efficient energetic utilization of substrates. Organisms relying on oxygen evolved complex structures for oxygen delivery and biochemical machineries dealing with its safe utilization and the ability to overcome the potentially harmful consequences of changes in oxygen availability. On fact, cells composing complex Eukaryotic organisms are set to live within an optimum narrow range of oxygen, quite specific for each cell type. Minute modifications of oxygen availability, either positive or negative, induce the expression of specific genes, the major actors of this responses being the transcription factors HIF and Nrf2 that control the attempt to cope with low oxygen (hypoxia) or to either high oxygen or to an oxygen "overflow," respectively. This review describes the interaction between these two transcription factors and their interaction with the transcription factor NF-κB acting as a pivotal determinant of final cell response. © 2018 BioFactors, 44(3):207-218, 2018.

miR-128 Is Implicated in Stress Responses by Targeting MAFG in Skeletal Muscle Cells

MAFG (v-Maf avian musculoaponeurotic fibrosarcoma oncogene homolog G) is a bZIP-type transcriptional regulator that belongs to the small MAF (sMAFs) protein family. By interacting with other bZIP transcription factors, sMAFs can form homo- and heterodimers governing either repressive or activating transcriptional functions. As heterodimeric partner of Nrf2, MAFG positively influences the ARE-dependent antioxidant/xenobiotic pathways, at least in condition of a correct MAFG:Nrf2 balance. MicroRNAs (miRs) participate to different regulatory networks being involved as fine-tuning regulators of gene expression. However, the connections between cellular surveillance to stresses mediated by MAFG:Nrf2 and miR regulations are not well understood. Here, we explored the impact of miR-128 in expression of genes related to stress response. Bioinformatic predictions coupled with functional analysis revealed the presence of miR-128 binding site in the 3′UTR of MAFG. Ectopic miR-128 expression correlated with reduced expression of endogenous MAFG-dependent genes and negatively affected ARE-mediated molecular phenotype based on Nrf2 activity. Indeed, miR-128 impairs redox-dependent pathways induced in response to oxidative stress. Moreover, in condition of hypoxia, MAFG induction correlated with reduced levels of miR-128. This lead to increased mRNA levels of HMOX-1 and x-CT for blunting stress. Overall, these findings identify MAFG as novel direct target of miR-128.

The zebrafish miR-125c is induced under hypoxic stress via hypoxia-inducible factor 1α and functions in cellular adaptations and embryogenesis

Hypoxia is a unique environmental stress. Hypoxia inducible factor-lα (HIF-lα) is a major transcriptional regulator of cellular adaptations to hypoxic stress. MicroRNAs (miRNAs) as posttranscriptional gene expression regulators occupy a crucial role in cell survival under low-oxygen environment. Previous evidences suggested that miR-125c is involved in hypoxia adaptation, but its precise biological roles and the regulatory mechanism underlying hypoxic responses remain unknown. The present study showed that zebrafish miR-125c is upregulated by hypoxia in a Hif-lα-mediated manner in vitro and in vivo. Dual-luciferase assay revealed that cdc25a is a novel target of miR-125c. An inverse correlation between miR-125c and cdc25a was further confirmed in vivo, suggesting miR-125c as a crucial physiological inhibitor of cdc25a which responds to cellular hypoxia. Overexpression of miR-125c suppressed cell proliferation, led to cell cycle arrest at the G1 phase in ZF4 cells and induced apoptotic responses during embryo development. More importantly, miR-125c overexpression resulted in severe malformation and reduction of motility during zebrafish embryonic development. Taken together, we conclude that miR-125c plays a pivotal role in cellular adaptations to hypoxic stress at least in part through the Hif-1α/miR-125c/cdc25a signaling and has great impact on zebrafish early embryonic development.

Differential microRNA expression in human placentas of term intra-uterine growth restriction that regulates target genes mediating angiogenesis and amino acid transport

Placental insufficiency leading to intrauterine growth restriction (IUGR) demonstrates perturbed gene expression affecting placental angiogenesis and nutrient transfer from mother to fetus. To understand the post-transcriptional mechanisms underlying such placental gene expression changes, our objective was to identify key non-coding microRNAs that express biological function. To this end, we initially undertook microarrays targeting microRNAs in a small sub-set of placentas of appropriate (AGA) versus small for gestational age (SGA) weight infants, and observed up-regulation of 97 miRs and down-regulation of 44 miRs in SGA versus AGA. In a larger cohort of samples (AGA, n = 21; SGA, n = 11; IUGR subset, n = 5), we validated by qRT-PCR differential expression of three specific microRNAs (miR-10b, -363 and -149) that target genes mediating angiogenesis and nutrient transfer. Validation yielded an increase in miR-10b and -363 expression of ~2.5-fold (p<0.02 each) in SGA versus AGA, and of ~3-fold (p<0.005) in IUGR versus AGA, with no significant change despite a trending increase in miR-149. To further establish a cause-and-effect paradigm, employing human HTR8 trophoblast cells, we assessed the effect of nutrient deprivation on miR expression and inhibition of endogenous miRs on target gene expression. In-vitro nutrient deprivation (~50%) increased the expression of miR-10b and miR-149 by 1.5-fold (p<0.02) while decreasing miR-363 (p<0.0001). Inhibition of endogenous miRs employing antisense sequences against miR-10b, -363 and -149 revealed an increase respectively in the expression of the target genes KLF-4 (transcription factor which regulates angiogenesis), SNAT1 and 2 (sodium coupled neutral amino acid transporters) and LAT2 (leucine amino acid transporter), which translated into a similar change in the corresponding proteins. Finally to establish functional significance we performed dual-luciferase reporter assays with 3'-insertion of miR-10b alone and observed a ~10% reduction in the 5'-luciferase activity versus the control. Lastly, we further validated by microarray and employing MirWalk software that the pathways and target genes identified by differentially expressed miRs in SGA/IUGR compared to AGA are consistent in a larger cohort. We have established the biological significance of various miRs that target common transcripts mediating pathways of importance, which are perturbed in the human IUGR placenta.