microRNA‐874 inhibition targeting STAT3 protects the heart from ischemia–reperfusion injury by attenuating cardiomyocyte apoptosis in a mouse model

Sevoflurane attenuates myocardial ischemia/reperfusion injury by up-regulating microRNA-99a and down-regulating BRD4

PURPOSE

It has been explored that sevoflurane (Sevo) is cardioprotective in myocardial ischemia/reperfusion injury (MI/RI) and mediates microRNA (miRNA) expression that control various physiological systems. Enlightened by that, the work was programmed to decode the mechanism of Sevo and miR-99a with the participation of bromodomain-containing protein 4 (BRD4).

METHODS

MI/RImodel was established on mice. MI/RI modeled mice were exposed to Sevo or injected with miR-99a or BRD4-related vectors to identify their functions in cardiac function, pathological injury, cardiomyocyte apoptosis, inflammation, and oxidative stress in MI/RI mice. MiR-99a and BRD4 expression in myocardial tissues were tested, and their relation was further validated.

RESULTS

MiR-99a was down-regulated, and BRD4 was up-regulated in MI/RI mice. Sevo up-regulated miR-99a to inhibit BRD4 expression in myocardial tissues of MI/RI mice. Sevo improved cardiac function, relieved myocardial injury, repressed cardiomyocyte apoptosis, and alleviated inflammation and oxidative stress in mice with MI/RI. MiR-99a restoration further enhanced the positive effects of Sevo on mice with MI/RI. Overexpression of BRD4 reversed up-regulation of miR-99a-induced attenuation of MI/RI in mice.

CONCLUSIONS

The work delineated that Sevo up-regulates miR-99a to attenuate MI/RI by inhibiting BRD4.

MiR-874-5p targets VDR/NLRP3 to reduce intestinal pyroptosis and improve intestinal barrier damage in sepsis

BACKGROUND

Vitamin D receptor (VDR) is associated with intestinal barrier damage in sepsis. However, the mechanism of action of miR-874-5p/VDR/NLRP3 axis in disease has not been clearly explained. Therefore, the main content of this study is to explore the mechanism of this axis in intestinal barrier damage in sepsis.

METHODS

In order to confirm the progress of miR-874-5p regulation of VDR/NLRP3 pathway and its involvement in intestinal barrier damage in sepsis, a series of molecular biology and cell biology methods were carried out in this study. These include the establishment of cecal ligation puncture model, Western blot, RT-qPCR, hematoxylin and eosin staining, double luciferase reporting method, Fluorescence in situ hybridization, immunohistochemistry, and enzyme-linked immunosorption assay.

RESULTS

The expression level of miR-874-5p was higher and that of VDR was lower in sepsis. miR-874-5p was negatively correlated with VDR. Inhibition of miR-874-5p expression increased the expression of VDR, decreased the expression of NLRP3, reduced caspase-1 activation and IL-1β secretion, reduced pyroptosis and inflammatory response, and thus protected the intestinal barrier damage in sepsis, all of which were reversed by the downregulation of VDR.

CONCLUSIONS

This study suggested that down-regulation of miR-874-5p or up-regulation of VDR could reduce intestinal barrier damage in sepsis, which may provide potential biomarkers and therapeutic targets for intestinal barrier damage in sepsis.

The crosstalk between STAT3 and microRNA in cardiac diseases and protection

Signal transducer and activator of transcription 3 (STAT3), an important transcription factor and signaling molecule, play an important role in cardiac disease and protection. As a transcription factor, STAT3 upregulates anti-oxidative and anti-apoptotic genes but suppresses anti-inflammatory and anti-fibrotic genes in cardiac disease and protection. As a signaling molecule, STAT3 is the downstream or upstream of other molecules for signaling transduction, also activated in cardiac disease and protection. MicroRNAs (miRNAs) are endogenous short non-coding RNAs that regulate mRNA expression at the transcriptional level and prevent protein translation. Recently, STAT3 is reported to be not only the target of miRNA but also the inhibitor or inducer of miRNA to modify the mRNA expression profiles in cardiomyocytes resulting in different effects on cardiac disease and protection. We summarize the current knowledge on STAT3 regulation of individual miRNAs and the modulation of STAT3 by miRNAs in cardiac diseases and protection.

miR-874: An Important Regulator in Human Diseases

miR-874 is located at 5q31.2, which is frequently deleted in cancer. miR-874 is downregulated in 22 types of cancers and aberrantly expressed in 18 types of non-cancer diseases. The dysfunction of miR-874 is not only closely related to the diagnosis and prognosis of tumor patients but also plays an important role in the efficacy of tumor chemotherapy drugs. miR-874 participates in the ceRNA network of long non-coding RNAs or circular RNAs, which is closely related to the occurrence and development of cancer and other non-cancer diseases. In addition, miR-874 is also involved in the regulation of multiple signaling pathways, including the Wnt/β-catenin signaling pathway, Hippo signaling pathway, PI3K/AKT signaling pathway, JAK/STAT signaling pathway, and Hedgehog signaling pathway. This review summarizes the molecular functions of miR-874 in the biological processes of tumor cell survival, apoptosis, differentiation, and tumorigenesis, and reveal the value of miR-874 as a cancer biomarker in tumor diagnosis and prognosis. Future work is necessary to explore the potential clinical application of miR-874 in chemotherapy resistance.

Isoflurane and low-level carbon monoxide exposures increase expression of pro-survival miRNA in neonatal mouse heart

Anesthetics such as isoflurane are known to cause apoptosis in the developing mammalian brain. However, isoflurane may have protective effects on the heart via relieving ischemia and downregulating genes related to apoptosis. Ischemic preconditioning, e.g. through the use of low levels of carbon monoxide (CO), has promise in preventing ischemia-reperfusion injury and cell death. However, it is still unclear how it either triggers the stress response in neonatal hearts. For this reason, thirty-three microRNAs (miRNAs) known to be differentially expressed following anesthesia and/or ischemic or hypoxic heart damage were investigated in the hearts from neonatal mice exposed to isoflurane or low level of CO, using an air-exposed control group. Only miR-93-5p increased with isoflurane exposure, which may be associated with the suppression of cell death, autophagy, and inflammation. By contrast, twelve miRNAs were differentially expressed in the heart following CO treatment. Many miRNAs previously shown to be responsible for suppressing cell death, autophagy, and myocardial hypertrophy were upregulated (e.g., 125b-3p, 19-3p, and 21a-5p). Finally, some miRNAs (miR-103-3p, miR-1a-3p, miR-199a-1-5p) which have been implicated in regulating energy balance and cardiac contraction were also differentially expressed. Overall, this study demonstrated that CO-mediated miRNA regulation may promote ischemic preconditioning and cardioprotection based on the putative protective roles of the differentially expressed miRNAs explored herein and the consistency of these results with those that have shown positive effects of CO on heart viability following anesthesia and ischemia-reperfusion stress.

Mitochondrial quality control mechanisms as molecular targets in cardiac ischemiareperfusion injury

Mitochondrial damage is a critical contributor to cardiac ischemia/reperfusion (I/R) injury. Mitochondrial quality control (MQC) mechanisms, a series of adaptive responses that preserve mitochondrial structure and function, ensure cardiomyocyte survival and cardiac function after I/R injury. MQC includes mitochondrial fission, mitochondrial fusion, mitophagy and mitochondria-dependent cell death. The interplay among these responses is linked to pathological changes such as redox imbalance, calcium overload, energy metabolism disorder, signal transduction arrest, the mitochondrial unfolded protein response and endoplasmic reticulum stress. Excessive mitochondrial fission is an early marker of mitochondrial damage and cardiomyocyte death. Reduced mitochondrial fusion has been observed in stressed cardiomyocytes and correlates with mitochondrial dysfunction and cardiac depression. Mitophagy allows autophagosomes to selectively degrade poorly structured mitochondria, thus maintaining mitochondrial network fitness. Nevertheless, abnormal mitophagy is maladaptive and has been linked to cell death. Although mitochondria serve as the fuel source of the heart by continuously producing adenosine triphosphate, they also stimulate cardiomyocyte death by inducing apoptosis or necroptosis in the reperfused myocardium. Therefore, defects in MQC may determine the fate of cardiomyocytes. In this review, we summarize the regulatory mechanisms and pathological effects of MQC in myocardial I/R injury, highlighting potential targets for the clinical management of reperfusion.

AMPKα2 Overexpression Reduces Cardiomyocyte Ischemia-Reperfusion Injury Through Normalization of Mitochondrial Dynamics

Cardiac ischemia-reperfusion (I/R) injury is associated with mitochondrial dysfunction. Recent studies have reported that mitochondrial function is determined by mitochondrial dynamics. Here, we hypothesized that AMPKα2 functions as an upstream mediator that sustains mitochondrial dynamics in cardiac I/R injury and cardiomyocyte hypoxia-reoxygenation (H/R) in vitro. To test this, we analyzed cardiomyocyte viability and survival along with mitochondrial dynamics and function using western blots, qPCR, immunofluorescence, and ELISA. Our results indicated that both AMPKα2 transcription and translation were reduced by H/R injury in cardiomyocytes. Decreased AMPKα2 levels were associated with cardiomyocyte dysfunction and apoptosis. Adenovirus-mediated AMPKα2 overexpression dramatically inhibited H/R-mediated cardiomyocyte damage, possibly by increasing mitochondrial membrane potential, inhibiting cardiomyocyte oxidative stress, attenuating intracellular calcium overload, and inhibiting mitochondrial apoptosis. At the molecular level, AMPKα2 overexpression alleviated abnormal mitochondrial division and improved mitochondrial fusion through activation of the Sirt3/PGC1α pathway. This suggests AMPKα2 contributes to maintaining normal mitochondrial dynamics. Indeed, induction of mitochondrial dynamics disorder abolished the cardioprotective effects afforded by AMPKα2 overexpression. Thus, cardiac I/R-related mitochondrial dynamics disorder can be reversed by AMPKα2 overexpression in a manner dependent on the activation of Sirt3/PGC1α signaling.

MicroRNA-874-3p Aggravates Doxorubicin-Induced Renal Podocyte Injury via Targeting Methionine Sulfoxide Reductase B3

Clinical application of doxorubicin (Dox) is limited due to its serious side effects including nephrotoxicity, and kidney podocytes play important roles in renal diseases. MicroRNAs (miRNAs) are critical regulators associated with human diseases. The purpose of this study was to explore a novel target in adjusting Dox-induced renal podocyte injury. Through a double luciferase reporter gene experiment, it was found that miR-874-3p directly targeted methionine sulfoxide reductase B3 (MsrB3). During the tests of miR-874-3p inhibitor and MsrB3 siRNA in human podocytes or miR-874-3p antagomir in mice, we found that the expression levels of downstream oxidative stress and apoptosis-related proteins were regulated by miR-874-3p/MsrB3 signal to alleviate or aggravate renal podocyte injury. The data in the present work showed that miR-874-3p aggravated Dox-caused renal podocyte injury by promoting apoptosis and oxidative damage via inhibiting MsrB3. Therefore, miR-874-3p/MsrB3 should be considered as a new therapeutic target in controlling renal podocyte injury induced by Dox.

JLX001 improves myocardial ischemia-reperfusion injury by activating Jak2-Stat3 pathway

AIMS

To investigate the preclinical pharmacodynamics and mechanism of JLX001 against myocardial ischemia reperfusion (MI/R) for clinical application.

MATERIALS AND METHODS

In vivo, SD rats were given intragastric administration for 5 days, and the MI/R model was established by ligating/releasing the left anterior descending coronary artery. In vitro, the oxygen-glucose deprivation/reperfusion (OGD/R) model was established after the drug was pre-incubated for 24 h in H9C2 cells. The infract size was determined by TTC staining. Left ventricular function of MI/R rats was detected by echocardiography. The level of histopathological score was determined by hematoxylin-eosin (HE) staining. The level of superoxide dismutase (SOD), malondialdehyde (MDA), creatine kinase (CK), lactic dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were determined by relevant kits. The level of apoptosis was measured by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Hoechst staining. The expression of p-Jak2, p-Stat3, Bax, Bcl-2, TNF-α, IL-1β protein were determined by western blot.

KEY FINDINGS

JLX001 can significantly improve left ventricular function, reduce myocardial infract size, histopathological score, the level of MDA, CK, LDH, TNF-α, IL-1β and the expression of Bax protein, significantly increase the activity of SOD, Bcl-2 protein expression, p-Jak2 protein expression, p-Stat3 protein expression in rat heart tissues and H9C2 cells. These effects can be reversed by AG490 which is a specific inhibitor of Jak2-Stat3 pathway.

SIGNIFICANCE

JLX001 can alleviate MI/R injury by inhibiting myocardial apoptosis, inflammation, and oxidative stress via Jak2-Stat3 pathway in vivo and in vitro.

Hypercholesterolemia Interferes with Induction of miR-125b-1-3p in Preconditioned Hearts

Ischemic preconditioning (IPre) reduces ischemia/reperfusion (I/R) injury in the heart. The non-coding microRNA miR-125b-1-3p has been demonstrated to play a role in the mechanism of IPre. Hypercholesterolemia is known to attenuate the cardioprotective effect of preconditioning; nevertheless, the exact underlying mechanisms are not clear. Here we investigated, whether hypercholesterolemia influences the induction of miR-125b-1-3p by IPre. Male Wistar rats were fed with a rodent chow supplemented with 2% cholesterol and 0.25% sodium-cholate hydrate for 8 weeks to induce high blood cholesterol levels. The hearts of normo- and hypercholesterolemic animals were then isolated and perfused according to Langendorff, and were subjected to 35 min global ischemia and 120 min reperfusion with or without IPre (3 × 5 min I/R cycles applied before index ischemia). IPre significantly reduced infarct size in the hearts of normocholesterolemic rats; however, IPre was ineffective in the hearts of hypercholesterolemic animals. Similarly, miR-125b-1-3p was upregulated by IPre in hearts of normocholesterolemic rats, while in the hearts of hypercholesterolemic animals IPre failed to increase miR-125b-1-3p significantly. Phosphorylation of cardiac Akt, ERK, and STAT3 was not significantly different in any of the groups at the end of reperfusion. Based on these results we propose here that hypercholesterolemia attenuates the upregulation of miR-125b-1-3p by IPre, which seems to be associated with the loss of cardioprotection.

How microRNAs affect the PD-L1 and its synthetic pathway in cancer

Programmed cell death-ligand 1 (PD-L1) is a glycoprotein that is expressed on the cell surface of both hematopoietic and nonhematopoietic cells. PD-L1 play a role in the immune tolerance and protect self-tissues from immune system attack. Dysfunction of this molecule has been highlighted in the pathogenesis of tumors, autoimmunity, and infectious disorders. MicroRNAs (miRNAs) are endogenous molecules that are classified as small non-coding RNA with approximately 20-22 nucleotides (nt) length. The function of miRNAs is based on complementary interactions with target mRNA via matching completely or incompletely. The result of this function is decay of the target mRNA or preventing mRNA translation. In the past decades, several miRNAs have been discovered which play an important role in the regulation of PD-L1 in various malignancies. In this review, we discuss the effect of miRNAs on PD-L1 expression and consider the effect of miRNAs on the synthetic pathway of PD-L1, especially during cancers.

Cardioprotective effect of isorhamnetin against myocardial ischemia reperfusion (I/R) injury in isolated rat heart through attenuation of apoptosis

In this study, we investigated the effects of isorhamnetin on myocardial ischaemia reperfusion (I/R) injury in Langendorff‐perfused rat hearts. Isorhamnetin treatment (5, 10 and 20 μg/mL) significantly alleviated cardiac morphological injury, reduced myocardial infarct size, decreased the levels of marker enzymes (LDH and CK) and improved the haemodynamic parameters, reflected by the elevated levels of the left ventricular developed pressure (LVDP), coronary flow (CF) and the maximum up/down velocity of left ventricular pressure (+dp/dt_max). Moreover, isorhamnetin reperfusion inhibited apoptosis of cardiomyocytes in the rats subjected to cardiac I/R in a dose‐dependent manner concomitant with decreased protein expression of Bax and cleaved‐caspase‐3, as well as increased protein expression of Bcl‐2. In addition, I/R‐induced oxidative stress was manifestly mitigated by isorhamnetin treatment, as showed by the decreased malondialdehyde (MDA) level and increased antioxidant enzymes activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‐Px). These results indicated that isorhamnetin exerts a protective effect against I/R‐induced myocardial injury through the attenuation of apoptosis and oxidative stress.

The lncRNA ROR/miR-124-3p/TRAF6 axis regulated the ischaemia reperfusion injury-induced inflammatory response in human cardiac myocytes

Myocardial ischaemia reperfusion injury (MIRI) is considered the primary cause of death in patients with cardiovascular diseases. Recently, long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been found to be involved in the pathogenesis of MIRI. However, whether lncRNA ROR and miR-124-3p play roles in MIRI and the underlying mechanism remain undetermined. HCMs were exposed to hypoxic conditions for 2 h followed by re-oxygenation (H/R) treatment. Expression of miR-124-3p and lncRNA ROR in HCMs was measured by qRT-PCR. TRAF6 expression was evaluated by qRT-PCR and western blotting. ELISA and qRT-PCR were conducted to assess the production of TNF-α, IL-6, and IL-1β. The interaction between miR-124-3p and TRAF6, as well as between miR-124-3p and lncRNA ROR, was verified by dual-luciferase reporter assay. Cell apoptosis was detected by flow cytometry analysis. Our data revealed that miR-124-3p was significantly downregulated, while TRAF6 and lncRNA ROR were upregulated in both MIRI rat model and H/R treated HCMs. Overexpression of miR-124-3p reversed the H/R-induced cell apoptosis and upregulation of TNF-α, IL-6, and IL-1β. Mechanistically, miR-124-3p bound and negatively regulated TRAF6 expression in HCMs. Moreover, TRAF6 overexpression significantly blocked the effects of miR-124-3p mimics on cell apoptosis and inflammatory response of HCMs, which involved the NF-κB pathway. Further analysis showed that lncRNA ROR sponged and negatively regulated miR-124-3p in HCMs. Overexpression of IL-1β was demonstrated to promote H/R induced cell apoptosis in HCMs. In addition, overexpression of ROR further enhanced the H/R-induced inflammation and cell apoptosis through its action on miR-124-3p. The lncRNA ROR/miR-124-3p/TRAF6 axis regulated the H/R-induced cell apoptosis and inflammatory response of HCMs.

Proteinase‑activated receptor 2 deficiency is a protective factor against cardiomyocyte apoptosis during myocardial ischemia/reperfusion injury

Previous studies have established that proteinase‑​activated receptor 2 (PAR2) activation protects against myocardial ischemia/reperfusion injury (MI/RI). However, the role of PAR2 deficiency in MI/RI remains unclear. The aim of the present study was to examine the effect of PAR2 deficiency on cardiomyocyte apoptosis and to clarify the potential molecular mechanisms for its protective effect against MI/RI. Using a mouse model of MI/RI, cardiac function was evaluated by echocardiography, infarct size was assessed by triphenyltetrazolium chloride staining, and myocardial cell apoptosis was measured by terminal deoxynucleotide transferase‑mediated dUTP nick end‑labeling staining. Annexin V/propidium iodide staining, and expression of Bcl‑2 and cleaved PARP were determined to assess apoptosis in myocardial H9c2 cells exposed to hypoxia/reoxygenation (H/R) injury‑simulating MI/RI. Phosphorylated ERK1/2, JNK, and p38 MAPK protein expression levels were analyzed by western blotting. The findings indicated that PAR2 deficiency markedly reduced cardiomyocyte apoptosis in the MI/RI mouse model, as well as in myocardial H9c2 cells exposed to H/R. Furthermore, PAR2 knockdown clearly prevented phosphorylation of ERK1/2 and JNK in myocardial H9c2 cells. The results revealed that PAR2 deficiency alleviated MI/RI‑associated apoptosis by inhibiting phosphorylation of ERK1/2 and JNK. Therefore, targeted PAR2 silencing may be a potential therapeutic approach for alleviation of MI/RI.

The Protective Effect of Magnesium Lithospermate B on Hepatic Ischemia/Reperfusion via Inhibiting the Jak2/Stat3 Signaling Pathway

Acute inflammation is an important component of the pathogenesis of hepatic ischemia/reperfusion injury (HIRI). Magnesium lithospermate B (MLB) has strong neuroprotective and cardioprotective effects. The purpose of this study was to determine whether MLB had underlying protective effects against hepatic I/R injury and to reveal the potential mechanisms related to the hepatoprotective effects. In this study, we first examined the protective effect of MLB on HIRI in mice that underwent 1 h ischemia followed by 6 h reperfusion. MLB pretreatment alleviated the abnormal liver function and hepatocyte damage induced by I/R injury. We found that serum inflammatory cytokines, including IL-6, IL-1β, and TNF-α, were significantly decreased by MLB during hepatic ischemia/reperfusion (I/R) injury, suggesting that MLB may alleviate hepatic I/R injury via inhibiting inflammatory signaling pathways. Second, we investigated the protein level of p-Jak2/Jak2 and p-Stat3/Stat3 using Western blotting and found that MLB could significantly inhibit the activation of the Jak2/Stat3 signaling pathway, which was further verified by AG490 in a mouse model. Finally, the effect of MLB on the Jak2/Stat3 pathway was further assessed in an in vitro model of RAW 264.7 cells; 1 µg/ml LPS induced the secretion of inflammatory mediators, including IL-6, TNF-α, and activation of the Jak2/Stat3 signaling pathway. MLB significantly inhibited the abnormal secretion of inflammatory factors and the activation of the Jak2/Stat3 signaling pathway in RAW264.7 cells. In conclusion, MLB was found for the first time to reduce inflammation induced by hepatic I/R via suppressing the Jak2/Stat3 pathway.

microRNA-193b protects against myocardial ischemia-reperfusion injury in mouse by targeting mastermind-like 1

The current study aimed to explore the functions and roles of microRNA-193b (miR-193b) in the myocardium with ischemia-reperfusion (I/R) injury and a potential therapeutic method for myocardial I/R injury. The mice were subjected to myocardial I/R with or without miR-193b pretreatment. The infarct size and myocardial enzymes were detected. The terminal deoxynucleotidyl transferase dUTP nick-end labeling assay was conducted to investigate the effect of miR-193b on cardiomyocyte apoptosis. The expression levels of miR-193b and mastermind-like 1 (MAML1) were validated by quantitative real-time polymerase chain reaction and Western blot analysis. The results suggested that the miR-193b expression level was significantly downregulated in the myocardium with I/R injury compared with control group. miR-193b overexpression is able to reduce infarct size and myocardial enzymes after myocardial I/R injury. Furthermore, overexpression of miR-193b could alleviate the apoptosis level after myocardial I/R injury. Taken together, the present study demonstrated that upregulated miRNA-193b alleviated myocardial I/R injury via targeting MAML1.