MicroRNA-122 promotes cardiomyocyte hypertrophy via targeting FoxO3

Isoliquiritigenin alleviates myocardial ischemia-reperfusion injury by regulating the Nrf2/HO-1/SLC7a11/GPX4 axis in mice

Ischemia-reperfusion (I/R) injury, a multifaceted pathological process, occurs when the prolongation of reperfusion duration triggers ferroptosis-mediated myocardial damage. Isoliquiritigenin (ISL), a single flavonoid from licorice, exhibits a wide range of pharmacological impacts, but its function in ferroptosis caused by myocardial I/R injury remains unclear. This study delved into the protective effect of ISL on myocardial I/R injury-induced ferroptosis and its mechanism. Neonatal mouse cardiomyocytes (NMCM) underwent hypoxia/reoxygenation (H/R) to simulate the pathological process of myocardial I/R. ISL significantly attenuated H/R-triggered production of reactive oxygen species in NMCM, reduced the expression of malondialdehyde and the activity of lactate dehydrogenase, enhanced superoxide dismutase and catalase activity, and increased the expression of nuclear factor E2-related factor 2 (Nrf2) and its downstream heme oxygenase 1 (HO-1), thereby mitigating oxidative stress damage. CCK8 experiment revealed that the ferroptosis inhibitor Ferrostatin-1 significantly improved myocardial cell viability after 24 h of reoxygenation, and ISL treatment showed a similar effect. ISL reduced intracellular free iron accumulation, up-regulated glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) expression, and inhibited lipid peroxidation accumulation, thereby alleviating ferroptosis. The Nrf2-specific inhibitor ML385 counteracted ISL's defensive role against H/R-triggered oxidative stress damage and ferroptosis. In vivo experiments further confirmed that by regulating the translocation of Nrf2 into the nucleus, ISL treatment increased the levels of HO-1, GPX4, and SLC7A11, inhibited the expression of ACSL4, Drp1 to exert the antioxidant role, alleviated mitochondrial damage, and ferroptosis, ultimately reducing myocardial infarction area and injury induced by I/R. ML385 nearly abolished ISL's protective impact on the I/R model by inhibiting Nrf2 function. In summary, ISL is capable of mitigating oxidative stress, mitochondrial damage, and cardiomyocyte ferroptosis caused by I/R, thereby reducing myocardial injury. A key mechanism includes triggering the Nrf2/HO-1/SLC7A11/GPX4 pathway to prevent oxidative stress damage and cardiomyocyte ferroptosis caused by I/R.

Current Concepts in the Epigenetic Regulation of Cardiac Fibrosis

Cardiac fibrosis is a significant driver of congestive heart failure, a syndrome that continues to affect a growing patient population globally. Cardiac fibrosis results from a constellation of complex processes at the transcription, receptor, and signaling axes levels. Various mediators and signaling cascades, such as the transformation growth factor-beta pathway, have been implicated in the pathophysiology of cardiac tissue fibrosis. Our understanding of these markers and pathways has improved in recent years as more advanced technologies and assays have been developed, allowing for better delineation of the crosstalk between specific factors. There is mounting evidence suggesting that epigenetic modulation plays a pivotal role in the progression of cardiac fibrosis. Transcriptional regulation of key pro- and anti-fibrotic pathways can accentuate or blunt the rate and extent of fibrosis at the tissue level. Exosomes, micro-RNAs, and long non-coding RNAs all belong to factors that can impact the epigenetic signature in cardiac fibrosis. Herein, we comprehensively review the latest literature about exosomes, their contents, and cardiac fibrosis. In doing so, we highlight the specific transcriptional factors with pro- or anti-fibrotic properties. We also assimilate the data supporting these mediators' potential utility as diagnostic or prognostic biomarkers. Finally, we offer insight into where further work can be done to fill existing gaps to translate pre-clinical findings better and improve clinical outcomes.

Dronedarone Attenuates Ang II-Induced Myocardial Hypertrophy Through Regulating SIRT1/FOXO3/PKIA Axis

BACKGROUND AND OBJECTIVES

Long-term pathological myocardial hypertrophy (MH) seriously affects the normal function of the heart. Dronedarone was reported to attenuate left ventricular hypertrophy of mice. However, the molecular regulatory mechanism of dronedarone in MH is unclear.

METHODS

Angiotensin II (Ang II) was used to induce cell hypertrophy of H9C2 cells. Transverse aortic constriction (TAC) surgery was performed to establish a rat model of MH. Cell size was evaluated using crystal violet staining and rhodamine phalloidin staining. Reverse transcription quantitative polymerase chain reaction and western blot were performed to detect the mRNA and protein expressions of genes. JASPAR and luciferase activity were conducted to predict and validate interaction between forkhead box O3 (FOXO3) and protein kinase inhibitor alpha (PKIA) promoter.

RESULTS

Ang II treatment induced cell hypertrophy and inhibited sirtuin 1 (SIRT1) expression, which were reversed by dronedarone. SIRT1 overexpression or PKIA overexpression enhanced dronedarone-mediated suppression of cell hypertrophy in Ang II-induced H9C2 cells. Mechanistically, SIRT1 elevated FOXO3 expression through SIRT1-mediated deacetylation of FOXO3 and FOXO3 upregulated PKIA expression through interacting with PKIA promoter. Moreover, SIRT1 silencing compromised dronedarone-mediated suppression of cell hypertrophy, while PKIA upregulation abolished the influences of SIRT1 silencing. More importantly, dronedarone improved TAC surgery-induced MH and impairment of cardiac function of rats via affecting SIRT1/FOXO3/PKIA axis.

CONCLUSIONS

Dronedarone alleviated MH through mediating SIRT1/FOXO3/PKIA axis, which provide more evidences for dronedarone against MH.

Mycn ameliorates cardiac hypertrophy-induced heart failure in mice by mediating the USP2/JUP/Akt/β-catenin cascade

BACKGROUND

Pathological cardiac hypertrophy is associated with cardiac dysfunction and is a key risk factor for heart failure and even sudden death. This study investigates the function of Mycn in cardiac hypertrophy and explores the interacting molecules.

METHODS

A mouse model of cardiac hypertrophy was induced by isoproterenol (ISO). The cardiac dysfunction was assessed by the heart weight-to-body weight ratio (HW/BW), echocardiography assessment, pathological staining, biomarker detection, and cell apoptosis. Transcriptome alteration in cardiac hypertrophy was analyzed by bioinformatics analysis. Gain- or loss-of-function studies of MYCN proto-oncogene (Mycn), ubiquitin specific peptidase 2 (USP2), and junction plakoglobin (JUP) were performed. The biological functions of Mycn were further examined in ISO-treated cardiomyocytes. The molecular interactions were verified by luciferase assay or immunoprecipitation assays.

RESULTS

Mycn was poorly expressed in ISO-treated mice, and its upregulation reduced HW/BW, cell surface area, oxidative stress, and inflammation while improving cardiac function of mice. It also reduced apoptosis of cardiomyocytes in mice and those in vitro induced by ISO. Mycn bound to the USP2 promoter to activate its transcription. USP2 overexpression exerted similar myocardial protective functions. It stabilized JUP protein by deubiquitination modification, which blocked the Akt/β-catenin pathway. Knockdown of JUP restored phosphorylation of Akt and β-catenin protein level, which negated the protective effects of USP2.

CONCLUSION

This study demonstrates that Mycn activates USP2 transcription, which mediates ubiquitination and protein stabilization of JUP, thus inactivating the Akt/β-catenin axis and alleviating cardiac hypertrophy-induced heart failure.

MicroRNAs (miRNAs) role in hypertension: pathogenesis and promising therapeutics

Background

MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a crucial role in regulating various cellular processes, including cell proliferation, differentiation, apoptosis, and disease development. Recent studies have highlighted the importance of miRNAs in the development and progression of essential hypertension, a common form of high blood pressure that affects millions of individuals worldwide. The molecular mechanisms by which miRNAs regulate hypertension are complex and multifaceted. MiRNAs target the 3' untranslated regions of mRNA molecules, thereby regulating the synthesis of specific proteins involved in cardiovascular function. For instance, miRNAs are known to regulate the expression of genes involved in blood vessel tone, cardiac function, and inflammation. The growing body of research on miRNAs in hypertension has highlighted their potential as therapeutic targets for managing this condition. Studies have shown that miRNA-based therapies can modulate the expression of key genes involved in hypertension, leading to improvements in blood pressure and cardiovascular function. However, more research is needed to fully understand the mechanisms of miRNA-mediated hypertension and to develop effective therapeutic strategies.

Conclusions

In summary, this review highlights the current understanding of the role of miRNAs in essential hypertension, including their molecular mechanisms and potential therapeutic applications. Further research is needed to fully understand the impact of miRNAs on hypertension and to develop new treatments for this common and debilitating condition.

MiR-378 Inhibits Angiotensin II-Induced Cardiomyocyte Hypertrophy by Targeting AKT2

Cardiomyocyte hypertrophy plays a crucial role in heart failure development, potentially leading to sudden cardiac arrest and death. Previous studies suggest that micro-ribonucleic acids (miRNAs) show promise for the early diagnosis and treatment of cardiomyocyte hypertrophy.To investigate the miR-378 expression in the cardiomyocyte hypertrophy model, reverse transcription-polymerase chain reaction (RT-qPCR), Western blot, and immunofluorescence tests were conducted in angiotensin II (Ang II)-induced H9c2 cells and Ang II-induced mouse model of cardiomyocyte hypertrophy. The functional interaction between miR-378 and AKT2 was studied by dual-luciferase reporter, RNA pull-down, Western blot, and RT-qPCR assays.The results of RT-qPCR analysis showed the downregulated expression of miR-378 in both the cell and animal models of cardiomyocyte hypertrophy. It was observed that the introduction of the miR-378 mimic inhibited the hypertrophy of cardiomyocytes induced by Ang II. Furthermore, the co-transfection of AKT2 expression vector partially mitigated the negative impact of miR-378 overexpression on Ang II-induced cardiomyocytes. Molecular investigations provided evidence that miR-378 negatively regulated AKT2 expression by interacting with the 3' untranslated region (UTR) of AKT2 mRNA.Decreased miR-378 expression and AKT2 activation are linked to Ang II-induced cardiomyocyte hypertrophy. Targeting miR-378/AKT2 axis offers therapeutic opportunity to alleviate cardiomyocyte hypertrophy.

MiR-122 knockdown regulates vascular smooth muscle cells phenotypic switching through enhanced FOXO3 expression

Vascular smooth muscle cells (VSMCs) phenotypic switching is identified as enhanced dedifferentiation, proliferation, and migration ability of VSMCs, in which microRNAs have been identified as important regulators of the process. The present study is aimed to explore the pathophysiological effect of miR-122 on VSMC phenotypic modulation. Here, the result showed that the decreased miR-122 expression was found in VSMCs subjected to platelet-derived growth factor-BB (PDGF-BB) treatment. Next, we investigated the response of miR-122 knockdown in VSMCs with PDGF-BB stimulation. MiR-122 silencing showed increased proliferation and migration capability, whereas attenuated the differentiation markers expression. The above results were reversed by miR-122 overexpression. Finally, we further demonstrated that FOXO3 was an important target for miR-122. Collectively, we demonstrated that miR-122 silencing promoted VSMC phenotypic modulation partially through upregulated FOXO3 expression that indicated miR-122 may be a novel therapeutic target for neointimal formation.

miRNAs Epigenetic Tuning of Wall Remodeling in the Early Phase after Myocardial Infarction: A Novel Epidrug Approach

Myocardial infarction (MI) is one of the leading causes of death in Western countries. An early diagnosis decreases subsequent severe complications such as wall remodeling or heart failure and improves treatments and interventions. Novel therapeutic targets have been recognized and, together with the development of direct and indirect epidrugs, the role of non-coding RNAs (ncRNAs) yields great expectancy. ncRNAs are a group of RNAs not translated into a product and, among them, microRNAs (miRNAs) are the most investigated subgroup since they are involved in several pathological processes related to MI and post-MI phases such as inflammation, apoptosis, angiogenesis, and fibrosis. These processes and pathways are finely tuned by miRNAs via complex mechanisms. We are at the beginning of the investigation and the main paths are still underexplored. In this review, we provide a comprehensive discussion of the recent findings on epigenetic changes involved in the first phases after MI as well as on the role of the several miRNAs. We focused on miRNAs function and on their relationship with key molecules and cells involved in healing processes after an ischemic accident, while also giving insight into the discrepancy between males and females in the prognosis of cardiovascular diseases.

Inhibition of microRNA-122 alleviates pyroptosis by targeting dual-specificity phosphatase 4 in myocardial ischemia/reperfusion injury

Pyroptosis is a type of programmed cell death that induces myocardial ischemia-reperfusion injury (I/RI), which leads to cardiac dysfunction and even lethal reperfusion injury. MiR-122 is a liver-specific miRNA associated with coronary heart disease, but its role in pyroptosis activation in myocardial I/RI remains unclear. Thus, this study aimed to determine whether miR-122 inhibition exerts myocardial I/RI protection in in vivo and in vitro models. An I/RI model was established in vivo using C57BL/J6 male mice. MiR-122 expression was upregulated in the heart tissues from the I/RI group. Quantitative results of echocardiography parameters showed that miR-122 inhibition improved cardiac function and downregulated interleukin (IL)-1β, IL-18, caspase 1, and caspase 11. However, pretransfection with recombinant adeno-associated virus type 9 encoding a DUSP4-specific siRNA (AAV9-siDUSP4) blocked the protective effects of miR-122 inhibition. A hypoxia/reoxygenation (H/R) model was established to mimic the I/R condition in vitro using H9C2 cells. Results showed that miR-122 inhibition increased superoxide dismutase activity (SOD) and cell viability and decreased malondialdehyde (MDA) level, IL-1β, IL-18, caspase 1, caspase 11, and cell death. These protective effects were abolished by transfection with DUSP4-specific siRNA. In summary, miR-122 expression is upregulated in I/RI, and miR-122 inhibition alleviates I/RI by suppressing pyroptosis through targeting DUSP4. Thus, miR-122 may be a novel therapeutic target for treating myocardial I/RI.

Identification of microRNA Transcriptome Involved in Bovine Intramuscular Fat Deposition

Background

Intramuscular fat deposition in beef is a major determinant of carcass quality and value in the USA. The objective of this study was to examine changes in microRNA (miRNA) transcriptome that are involved with intramuscular fat deposition with time-on-concentrates (TOC). Yearling steers were individually fed a high concentrate diet and changes in intramuscular fat deposition were monitored by real-time ultrasound at 28 to 33 d intervals. Longissimus muscle biopsies collected on d 0, 92 and 124 TOC to examine changes in miRNA transcriptome that are involved in intramuscular fat deposition.

Results

Steer body weight increased (P < 0.0001) at each weigh day during TOC. Fat thickness increased (P < 0.005) from d 28 to 124. Ribeye area was larger (P < 0.001) on d 124 than d 61, which was larger than d 0 and 28. Ultrasound intramuscular fat content was greater (P < 0.001) on d 92 and 124 compared to d 0, 28 or 61. Sequencing of the muscle biopsy samples identified one miRNA, bta-miR-122, that was up-regulated (P < 0.005) at d 92 and 124 compared to d 0. At d 92 TOC, mRNA expression levels of fatty acid binding protein 4 (FABP4) and elongase 6 (ELOVL6) were up-regulated (P < 0.01) compared to d 0; whereas at d 124, lipogenic genes involved in de novo fatty acid synthesis, fatty acid transport, elongation and desaturation were highly up-regulated compared to d0.

Conclusions

Small RNA sequencing identified bta-miR-122 as a potential miRNA of interest that may be involved in intramuscular fat deposition with increasing TOC. Increased intramuscular fat content, as measured by real-time ultrasound, combined with differential gene expression suggests that preadipocyte differentiation may be stimulated first, which is followed by a global up-regulation of lipogenic genes involved in de novo fatty acid synthesis that provide fatty acids for subsequent hypertrophy.

Neutrophil-like cell membrane-coated siRNA of lncRNA AABR07017145.1 therapy for cardiac hypertrophy via inhibiting ferroptosis of CMECs

Cardiac microvascular dysfunction is associated with cardiac hypertrophy and can eventually lead to heart failure. Dysregulation of long non-coding RNAs (lncRNAs) has recently been recognized as one of the key mechanisms involved in cardiac hypertrophy. However, the potential roles and underlying mechanisms of lncRNAs in cardiac microvascular dysfunction have not been explicitly delineated. Our results confirmed that cardiac microvascular dysfunction was related to cardiac hypertrophy and ferroptosis of cardiac microvascular endothelial cells (CMECs) occurred during cardiac hypertrophy. Using a combination of in vivo and in vitro studies, we identified a lncRNA AABR07017145.1, named as lncRNA AAB for short, and revealed that lncRNA AAB was upregulated in the hearts of cardiac hypertrophy rats as well as in the Ang II-induced CMECs. Importantly, we found that lncRNA AAB sponged and sequestered miR-30b-5p to induce the imbalance of MMP9/TIMP1, which enhanced the activation of transferrin receptor 1 (TFR-1) and then eventually led to the ferroptosis of CMECs. Moreover, we have developed a delivery system based on neutrophil membrane (NM)-camouflaged mesoporous silica nanocomplex (MSN) for inhibition of cardiac hypertrophy, indicating the potential role of silenced lncRNA AAB (si-AAB) and overexpressed miR-30b-5p as the novel therapy for cardiac hypertrophy.

MicroRNA-122-5p promotes renal fibrosis and injury in spontaneously hypertensive rats by targeting FOXO3

Hypertensive renal injury is accompanied by tubular interstitial fibrosis leading to increased risk for renal failure. This study aimed to explore the influences of miR-122-5p in hypertension-mediated renal fibrosis and damage. 14-week-old male SHR and WKY rats were randomly assigned to treat with rAAV-miR-122-5p or rAAV-GFP for 8 weeks. There were marked increases in miR-122-5p and Kim-1 levels and decreases in FOXO3 and SIRT6 levels in hypertensive rats. Transfection with rAAV-miR-122-5p triggered exacerbation of renal fibrosis, apoptosis and inflammatory injury in SHR, associated with downregulated levels of FOXO3, SIRT6, ATG5 and BNIP3 as well as upregulated expression of Kim-1, NOX4, CTGF, and TGF-β1. In cultured primary mouse renal tubular interstitial fibroblasts, exposure to angiotensin II resulted in obvious downregulation of FOXO3, SIRT6, ATG5, BNIP3 and nitric oxide levels as well as augmented cellular migration, oxidative stress, and inflammation, which were exacerbated by miR-122-5p mimic while rescued by miR-122-5p inhibitor and rhFOXO3, respectively. Notably, knockdown of FOXO3 strikingly blunted cellular protective effects of miR-122-5p inhibitor. In summary, miR-122-5p augments renal fibrosis, inflammatory and oxidant injury in hypertensive rats by suppressing the expression of FOXO3. Pharmacological inhibition of miR-122-5p has potential therapeutic significance for hypertensive renal injury and fibrosis-related kidney diseases.

Genome-wide identification of microRNA targets reveals positive regulation of the Hippo pathway by miR-122 during liver development

Liver development is a highly complex process that is regulated by the orchestrated interplay of epigenetic regulators, transcription factors, and microRNAs (miRNAs). Owing to the lack of global in vivo targets of all miRNAs during liver development, the mechanisms underlying the dynamic control of hepatocyte differentiation by miRNAs remain elusive. Here, using Argonaute (Ago) high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) in the mouse liver at different developmental stages, we characterized massive Ago-binding RNAs and obtained a genome-wide map of liver miRNA-mRNA interactions. The dynamic changes of five clusters of miRNAs and their potential targets were identified to be differentially involved at specific stages, a dozen of high abundant miRNAs and their epigenetic regulation by super-enhancer were found during liver development. Remarkably, miR-122, a liver-specific and most abundant miRNA in newborn and adult livers, was found by its targetome and pathway reporter analyses to regulate the Hippo pathway, which is crucial for liver size control and homeostasis. Mechanistically, we further demonstrated that miR-122 negatively regulates the outcomes of the Hippo pathway transcription factor TEAD by directly targeting a number of hippo pathway regulators, including the coactivator TAZ and a key factor of the phosphatase complex PPP1CC, which contributes to the dephosphorylation of YAP, another coactivator downstream of the Hippo pathway. This study identifies for the first time the genome-wide miRNA targetomes during mouse liver development and demonstrates a novel mechanism of terminal differentiation of hepatocytes regulated by the miR-122/Hippo pathway in a coordinated manner. As the Hippo pathway plays important roles in cell proliferation and liver pathological processes like inflammation, fibrosis, and hepatocellular carcinoma (HCC), our study could also provide a new insight into the function of miR-122 in liver pathology.

Circ-Zfp644 acts as a pro-hypertrophic mediator in an Ang-II induced in vitro myocardial hypertrophy model

Cardiac hypertrophy (CH) is a common risk factor for heart failure and even sudden cardiac death. Molecules have emerged as vital regulators in cardiac disorders. LIM domain kinase 1 (Limk1) is reported as a pro-fibrotic mediator in patients with permanent atrial fibrillation and it has also been suggested to aggravate cardiac dysfunction in rats with chronic heart failure. The present study observed that Limk1 was significantly upregulated in the in vitro model of CH induced by angiotensin II (Ang-II). Interestingly, silencing Limk1 led to inhibition of the hypertrophic phenotypes in Ang-II-treated cardiomyocytes. Next, through a series of mechanistic assays including RIP assay, RNA pull-down assay, and luciferase reporter assay, miR-93-5p was verified to target Limk1. Furthermore, circ-Zfp644 was validated as the sponge of miR-93-5p. Circ-Zfp644 functioned as a ceRNA to upregulate Limk1 expression via sequestering miR-93-5p in Ang-II-treated cardiomyocytes. Finally, a range of rescue assays revealed that circ-Zfp644 stimulated hypertrophic effects in Ang-II-treated cardiomyocytes via upregulating Limk1 while miR-93-5p exerted the opposite effects via its inhibition on Limk1. On the whole, the present study revealed that circ-Zfp644 aggravated CH through modulating the miR-93-5p/Limk1 axis. The findings observed on the in vitro model of CH provided new potential for developing CH treatment.

Inhibition of miR-122 reduced atherosclerotic lesion formation by regulating NPAS3-mediated endothelial to mesenchymal transition

AIMS

Endothelial to mesenchymal transition (EndMT) is closely related to atherosclerosis. Herein, we aim to determine whether miR-122 is involved in EndMT and the underlying mechanism in atherosclerosis.

MAIN METHODS

qRT-PCR was performed to detect miR-122 expression in ApoE^-/- mice and cellular EndMT model induced by H₂O₂. MiR-122 expression in vivo was modulated by lenti-virus injection and by genetic manipulation. Hematoxylin and eosin (HE) and Oil-red O staining were used to observe the plaque size and lipid accumulation in the aortic roots. F4/80 staining, elastin staining, and masson staining were used to observe the components of atherosclerotic lesions. MiR-122 expression in endothelial cells was modulated by transfection of miR-122 mimic and inhibitor. Western blotting and co-localization of endothelial markers (VE-cadherin, CD31) and mesenchymal markers (Vimentin, α-SMA) were carried out to determine EndMT.

KEY FINDINGS

MiR-122 was upregulated in the aortic intima and serum of ApoE^-/- mice induced by HFD and in cellular EndMT model. Inhibition of miR-122 repressed the atherosclerotic plaque progression and vulnerable plaque formation in ApoE^-/- mice. In vitro, endothelial cells acquired a spindle-shaped morphology accompanying decrease of the endothelial markers (VE-cadherin, CD31) and increase of the mesenchymal markers (Vimentin, α-SMA) in the presence of H₂O₂, which was inhibited by miR-122 inhibitor. Furthermore, NPAS3 functions as a target of miR-122, and NPAS3 silencing abolished the anti-EndMT effect of miR-122 inhibitor.

SIGNIFICANCE

Inhibition of miR-122 prevents atherosclerosis and regulates NPAS3-mediated EndMT, suggesting that miR-122 may be a novel target in the treatment of EndMT-associated diseases including atherosclerosis.

Overexpression of MicroRNA-122 Resists Oxidative Stress-Induced Human Umbilical Vascular Endothelial Cell Injury by Inhibition of p53

Deep venous thrombosis (DVT) constitutes a great threat to health worldwide. Endothelial cell injury and dysfunction comprise the critical contributor for the development of DVT. However, the mechanism behind it remains poorly elucidated. The study is aimed at investigating the role of microRNA-122 (miR-122) and oxidative stress on DVT. The results showed that miR-122 overexpression dampened H₂O₂-evoked cytotoxic injury in human umbilical vein endothelial cells (HUVECs) by increasing cell viability, suppressing cell apoptosis and oxidative stress injury. Notably, miR-122 overexpression attenuated provasoconstriction factor endothelin-1 (ET-1) expression in HUVECs exposed to H₂O₂ but enhanced the productions of vasodilatation factor Prostaglandin F1α (PGF1α). Moreover, inhibition of miR-122 had the opposite results. miR-122 could inhibit the expression of p53. Low expression of p53 could enhance the protection of miR-122 on HUVEC injury. This study highlights that miR-122 overexpression may restore H₂O₂-induced HUVEC injury by regulating the expression of p53.

Roles of MicroRNA-122 in Cardiovascular Fibrosis and Related Diseases

Fibrotic diseases cause annually more than 800,000 deaths worldwide, where of the majority accounts for cardiovascular fibrosis, which is characterized by endothelial dysfunction, myocardial stiffening and reduced dispensability. MicroRNAs (miRs), small noncoding RNAs, play critical roles in cardiovascular dysfunction and related disorders. Intriguingly, there is a critical link among miR-122, cardiovascular fibrosis, sirtuin 6 (SIRT6) and angiotensin-converting enzyme 2 (ACE2), which was recently identified as a coreceptor for SARS-CoV2 and a negative regulator of the rennin-angiotensin system. MiR-122 overexpression appears to exacerbate the angiotensin II-mediated loss of autophagy and increased inflammation, apoptosis, extracellular matrix deposition, cardiovascular fibrosis and dysfunction by modulating the SIRT6-Elabela-ACE2, LGR4-β-catenin, TGFβ-CTGF and PTEN-PI3K-Akt signaling pathways. More importantly, the inhibition of miR-122 has proautophagic, antioxidant, anti-inflammatory, anti-apoptotic and antifibrotic effects. Clinical and experimental studies clearly demonstrate that miR-122 functions as a crucial hallmark of fibrogenesis, cardiovascular injury and dysfunction. Additionally, the miR-122 level is related to the severity of hypertension, atherosclerosis, atrial fibrillation, acute myocardial infarction and heart failure, and miR-122 expression is a risk factor for these diseases. The miR-122 level has emerged as an early-warning biomarker cardiovascular fibrosis, and targeting miR-122 is a novel therapeutic approach against progression of cardiovascular dysfunction. Therefore, an increased understanding of the cardiovascular roles of miR-122 will help the development of effective interventions. This review summarizes the biogenesis of miR-122; regulatory effects and underlying mechanisms of miR-122 on cardiovascular fibrosis and related diseases; and its function as a potential specific biomarker for cardiovascular dysfunction.

MicroRNA and ROS Crosstalk in Cardiac and Pulmonary Diseases

Reactive oxygen species (ROS) affect many cellular functions and the proper redox balance between ROS and antioxidants contributes substantially to the physiological welfare of the cell. During pathological conditions, an altered redox equilibrium leads to increased production of ROS that in turn may cause oxidative damage. MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level contributing to all major cellular processes, including oxidative stress and cell death. Several miRNAs are expressed in response to ROS to mediate oxidative stress. Conversely, oxidative stress may lead to the upregulation of miRNAs that control mechanisms to buffer the damage induced by ROS. This review focuses on the complex crosstalk between miRNAs and ROS in diseases of the cardiac (i.e., cardiac hypertrophy, heart failure, myocardial infarction, ischemia/reperfusion injury, diabetic cardiomyopathy) and pulmonary (i.e., idiopathic pulmonary fibrosis, acute lung injury/acute respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, lung cancer) compartments. Of note, miR-34a, miR-144, miR-421, miR-129, miR-181c, miR-16, miR-31, miR-155, miR-21, and miR-1/206 were found to play a role during oxidative stress in both heart and lung pathologies. This review comprehensively summarizes current knowledge in the field.

MiR-30e-5p is sponged by Kcnq1ot1 and represses Angiotensin II-induced hypertrophic phenotypes in cardiomyocytes by targeting ADAM9

Prolonged cardiac hypertrophy, a pathological compensatory response of the heart, finally leads to heart failure. Numerous studies have illustrated the vital roles of non-coding RNAs (ncRNAs) in cardiac hypertrophy. Here, we probed into the role and probable mechanism of microRNA-30e-5p (miR-30e-5p) in Angiotensin II (Ang-II)-stimulated hypertrophic cardiomyocytes. Intriguingly, the expression of hypertrophic markers, cell surface area and protein/DNA ratio were all reduced in Ang-II-induced hypertrophic cardiomyocytes when miR-30e-5p expression was augmented. Then, ADAM9 was screened out as the target of miR-30e-5p and ADAM9 overexpression rescued the effect of miR-30e-5p upregulation in Ang-II-treated cardiomyocytes. Moreover, we identified Kcnq1ot1 as the upstream of miR-30e-5p/ADAM9 axis and verified that Kcnq1ot1 aggrandized ADAM9 expression in Ang-II-treated cardiomyocytes through absorbing miR-30e-5p. Furthermore, rescue assays confirmed that ADAM9 up-regulation abrogated the repressive effect of Kcnq1ot1 depletion on Ang-II-induced cardiac hypertrophy. In conclusion, Kcnq1ot1 sequestered miR-30e-5p to release ADAM9 to facilitate cardiac hypertrophy, indicating that Kcnq1ot1 might be used as a potentially therapeutic target for cardiac hypertrophy.

Loss of HNF1α Function Contributes to Hepatocyte Proliferation and Abnormal Cholesterol Metabolism via Downregulating miR-122: A Novel Mechanism of MODY3

PURPOSE

Mutations in hepatocyte nuclear factor 1α (HNF1α) are the cause of maturity-onset diabetes of the young type 3 (MODY3) and involved in the development of hepatocellular adenoma and abnormal lipid metabolism. Previously, we have found that the serum microRNA (miR)-122 levels in MODY3 patients were lower than those in type 2 diabetes mellitus and healthy controls. This study aimed to investigate the mechanism of decreased miR-122 levels in patients with MODY3 and whether low levels of miR-122 mediate tumorigenesis and abnormal lipid metabolism associated with HNF1α deficiency in human hepatocytes.

METHODS

The expression of miR-122 was examined by real-time PCR. Dual-luciferase reporter assay was performed to confirm the transcriptional regulation of miR-122 by HNF1α. HepG2 cells were transfected with siRNA or miRNA mimic to downregulate or upregulate the expression of HNF1α or miR-122, respectively. CCK-8 and colony formation assay were used to determine cell proliferation. Lipid accumulation was examined by Oil Red O staining and intracellular triglyceride and cholesterol quantification assays.

RESULTS

HNF1α regulated the expression of miR-122 by directly binding to its promoter. Knockdown of HNF1α in HepG2 cells reduced the expression of miR-122, increased proliferation and promoted intracellular cholesterol accumulation. Overexpression of miR-122 partially rescued the phenotypes associated with HNF1α deficiency in human hepatocytes. Mechanistically, HNF1α modulated cholesterol homeostasis via miR-122-dependent activation of sterol regulatory element-binding protein-2 (SREBP-2) and regulation of proprotein convertase subtilisin/kexin type 9 (PCSK9). Moreover, circulating miR-122 levels were associated with serum cholesterol levels.

CONCLUSION

Loss of HNF1α function led to hepatocyte proliferation and abnormal cholesterol metabolism by downregulating miR-122. Our findings revealed a novel mechanism that low levels of miR-122 mediate tumorigenesis and abnormal lipid metabolism associated with MODY3. MiR-122 may be a potential therapeutic target for the treatment of MODY3.