MicroRNA-499-5p inhibits transforming growth factor-β1-induced Smad2 signaling pathway and suppresses fibroblast proliferation and collagen synthesis in rat by targeting TGFβ-R1

BACKGROUND

Artial fibrosis has been recognized as a typical pathological change in atrial fibrillation. Although present evidence suggests that microRNA-499-5p (miR-499-5p) plays an important role in the development of atrial fibrosis, the specific mechanism is not fully understood. Therefore, this study attempted to assess the influence of miR-499-5p on atrial fibroblasts and explore the potential molecular mechanism.

METHODS

Atrial fibroblasts from sprague dawley rat were respectively transfected with miR-499-5p mimic, miR-499-5p negative control and miR-499-5p inhibitor, atrial fibroblasts without any treatment were also established. Cell counting kit-8 assay and transwell assay were used to detect the proliferation and migration of atrial fibroblasts in each group. Expressions of miR-499-5p, TGF-β1, smad2, α-SMA, collagen-I and TGFβ-R1 in mRNA and protein level were subsequently detected via quantitative real-time polymerase chain reaction and western blot. Furthermore, the prediction of the binding sites of miR-499-5p and TGFβ-R1 was performed via the bioinformatics online software TargetScan and verified by dual luciferase reporter.

RESULTS

By utilizing miR-499-5p-transfected atrial fibroblasts model, expression of miR-499-5p in the miR-499-5p mimic group was upregulated, while it was downregulated in the miR-499-5p inhibitors group. Upregulated miR-499-5p expression led to to a significant decrease in the proliferative and migratory ability of cultured atrial fibroblasts, while downregulated miR-499-5p expression led to a significant increase in the proliferative and migratory ability of cultured atrial fibroblasts. Additionally, upregulated miR-499-5p expression made a significant rise in TGF-β1-induced mRNA and protein expression of TGF-β1, TGFβ-R1, smad2, α-SMA and collagen-I in atrial fibroblasts. Furthermore, results from the dual luciferase reporter conformed that miR-499-5p may repress TGFβ-R1 by binding the 3'UTR of TGFβ-R1 directly.

CONCLUSIONS

miR-499-5p is able to inhibit the activation of transforming growth factor β-induced Smad2 signaling and eventually suppressed the proliferation, migration and invasion of atrial fibroblasts and collagen synthesis by targeting TGFβ-R1.

MicroRNA-499-5p promotes vascular smooth muscle cell proliferation and migration via inhibiting SOX6

Atherosclerosis (AS) is the primary etiology of cardiovascular disease, which is considered the leading cause of death all over the world. MicroRNA miR-499-5p was involved in the functional regulation of myocardial and skeletal muscle, whereas its role in atherosclerosis, especially in vascular smooth muscle cells (VSMCs), remains unclear. Our study aims to investigate the effects of miR-499-5p in the proliferation and migration of VSMCs and potential mechanisms. We used mouse aortic vascular smooth muscle cells (MOVAS) and ApoE^-/- mice to establish the models of AS in vitro and in vivo, respectively. RT-PCR was performed to detect the expression level of miR-499-5p. Subsequently, Cell Counting Kit-8 (CCK-8) assays, Transwell assays, and wound-healing assays were used to evaluate cell proliferation and migration. Dual-luciferase reporter assay was performed to validate the interaction between miR-499-5p and SOX6. miR-499-5p significantly increased in aorta tissues of mice in AS tissues and vascular smooth muscle cells treated with ox-LDL. miR-499-5p overexpression could promote the proliferation and migration of MOVAS. Bioinformatics analysis predicted and further experiments verified that miR-499-5p could directly bind to the 3'-untranslated region (UTR) region of SOX6. Further, miR-499-5p induced an increased expression of smooth muscle proliferation and migration-related genes, PCNA, cyclin D1, and matrix metalloproteinase (MMP2), as well as the decreased expression of proliferation inhibiting factor p21, which was significantly reversed by SOX6 overexpression. miR-499-5p boosts the proliferation and migration of smooth muscle cells by binding and inhibiting SOX6 expression. The miR-499-5p/SOX6 axis may present a promising therapeutic implication for the prevention and treatment of cardiovascular diseases.

Effect of miR-499-5p/SOX6 axis on atrial fibrosis in rats with atrial fibrillation

Atrial fibrosis is involved in the progression of atrial fibrillation (AF). miR-499-5p is the most downregulated microRNA in arrhythmogenic cardiomyopathy hearts. Sry-related high-mobility-group box 6 (SOX6) is associated with apoptosis, inflammatory responses, and fibrosis. This study investigated the mechanism of miR-499-5p in ameliorating AF rats by regulating SOX6. AF rat models were established by injecting Ach-CaCl₂ mixture, and the rats were treated with Lv-miR-499-5p/oe-SOX6/si-SOX6 before modeling. AF duration was recorded using electrocardiogram. miR-499-5p and SOX6 expression levels in the myocardium were determined by reverse transcription-quantitative polymerase chain reaction. The binding of miR-499-5p and SOX6 was validated. The atrial fibrosis degree and cardiomyocyte apoptosis were assessed using the Masson and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining methods. Levels of SOX6, atrial fibrosis markers (collage I/α-SMA/TGFβ1), cell cycle-related proteins (p21/CDC25/Cyclin B1), and cell senescence markers (SA-β-gal/γ-H2AX) were measured using Western blotting and immunohistochemistry. miR-499-5p was downregulated and SOX6 was upregulated in AF rats. miR-499-5p overexpression shortened the AF duration, alleviated atrial fibrosis, and decreased collage I/α-SMA/TGFβ1. miR-499-5p targeted SOX6 to ameliorate atrial fibrosis. AF rats exhibited increased p21/CDC25/Cyclin B1/SA-β-gal/γ-H2AX levels and raised cardiomyocyte apoptosis. SOX6 silencing downregulated p21 and alleviated cardiomyocyte cycle arrest, cell senescence, and apoptosis in AF rats. Shortly, miR-499-5p suppresses atrial fibrosis and cardiomyocyte senescence by targeting SOX6 and downregulating p21, thus mitigating AF in rats.

Tanshinone IIA improves cardiac function via regulating miR-499-5p dependent angiogenesis in myocardial ischemic mice

BACKGROUND/AIMS

Myocardial ischemia-reperfusion injury leads to aggravated cardiac remodeling and heart failure. After myocardial infarction (MI), angiogenesis plays a vital role in the repair and regeneration of tissue. The purpose of the current study was to determine the effect of Tanshinone IIA (Tan IIA) on angiogenesis and elucidate its related mechanism.

METHODS

The C57BL/6 mice MI model was established to evaluate the therapeutic effect of Tan IIA in vivo. MicroRNA (miRNA) microarray and bioinformatics analysis were performed to determine the differential expressions of miRNAs after Tan IIA administration. Cell proliferation, migration, and angiogenesis capacity were detected by EdU, Transwell, and Tube formation assay in vitro, respectively. The relationship between miR-499-5p (miR-499) and paired phosphate and tension homolog deleted on chromosome ten (PTEN) was confirmed by using a Dual-luciferase reporter assay.

RESULTS

Our results showed that Tan IIA administration improved cardiac function after MI by activating angiogenesis. Further miRNA microarray and bioinformatics analysis revealed that miR-499 was significantly down-regulated, while PTEN was remarkably upregulated after Tan IIA administration post-MI. In addition, we found that miR-499 knock-down effectively promotes cell proliferation, migration, and tube formation ability of HUVECs. Dual-luciferase reporter assay demonstrated that PTEN contains a direct binding site for miR-499-5p.

CONCLUSION

Tan IIA improves cardiac function post-MI by inducing angiogenesis. In terms of the mechanism, Tan IIA promotes therapeutic angiogenesis by regulating miR-499-5p/PTEN signaling pathway.

Circulating miR-499a-5p Is a Potential Biomarker of MYH7-Associated Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited myocardial disease with significant genetic and phenotypic heterogeneity. To search for novel biomarkers, which could increase the accuracy of HCM diagnosis and improve understanding of its phenotype formation, we analyzed the levels of circulating miRNAs—stable non-coding RNAs involved in post-transcriptional gene regulation. Performed high throughput sequencing of miRNAs in plasma of HCM patients and controls pinpointed miR-499a-5p as one of 35 miRNAs dysregulated in HCM. Further investigation on enlarged groups of individuals showed that its level was higher in carriers of pathogenic/likely pathogenic (P/LP) variants in MYH7 gene compared to controls (fold change, FC = 8.9; p < 0.0001). Just as important, carriers of variants in MYH7 gene were defined with higher miRNA levels than carriers of variants in the MYBPC3 gene (FC = 14.1; p = 0.0003) and other patients (FC = 4.1; p = 0.0008). The receiver operating characteristic analysis analysis showed the ability of miR-499a-5p to identify MYH7 variant carriers with the HCM phenotype with area under the curve value of 0.95 (95% confidence interval: 0.88−1.03, p = 0.0004); sensitivity and specificity were 0.86 and 0.91 (cut-off = 0.0014). Therefore, miR-499a-5p could serve as a circulating biomarker of HCM, caused by P/LP variants in MYH7 gene.

Suppression of MALAT1 alleviates neurocyte apoptosis and reactive oxygen species production through the miR-499-5p/SOX6 axis in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH), a common devastating cerebrovascular accident, is a great threat to human health and life. Exploration of the potential therapeutic target of SAH is urgently needed. Previous studies showed that long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) promotes cell apoptosis in various diseases, while its role in SAH remains unclear. In our study, we established a mouse model of SAH and used the oxyhemoglobin (OxyHb) to induce neuronal injury in vitro. Interestingly, MALAT1 was found upregulated in brain tissues of SAH mice and OxyHb-stimulated neurons. In addition, knockdown of MALAT1 attenuated apoptosis and decreased reactive oxygen species (ROS) production in OxyHb-stimulated neurons. Mechanistically, we demonstrated that MALAT1 bound with miR-499-5p. Furthermore, our findings indicated that miR-499-5p bound to SOX6 3' untranslated region (UTR) and negatively regulated SOX6 mRNA and protein levels. Rescue assays suggested that SOX6 overexpression counteracted the effects of MALAT1 knockdown on neurocyte apoptosis, and ROS production in OxyHb-stimulated neurons. The in vivo assays indicated that knockdown of MALAT1 improved brain injury of SAH mice. Our study demonstrates that silencing of MALAT1 alleviates neurocyte apoptosis and reduces ROS production through the miR-499-5p/SOX6 axis after SAH injury.

Inhibition of long non-coding RNA TUG1 protects against diabetic cardiomyopathy induced diastolic dysfunction by regulating miR-499-5p

Reportedly, several long non-coding RNAs (lncRNAs) have been involved in the regulation of cardiac hypertrophy induced by diabetic cardiomyopathy (DCM), causing cardiac dysfunction and subsequent failure. Although lncRNA taurine upregulated gene 1 (TUG1) is associated with myocardial injury, the expression profile and potential role of TUG1 in DCM-related cardiac hypertrophy remain unknown. This study elucidated the functions of TUG1 in DCM and its underlying mechanisms. Our results demonstrated that the expression of TUG1 was upregulated in db/db mice cardiomyocytes. Inhibition of TUG1 by lentivirus si-TUG1 indicated no effect on systolic function; however, it effectively improved DCM-induced diastolic dysfunction in db/db mice. TUG1 silencing demonstrated no influence on the metabolic characteristics of DCM, including blood glucose and lipid levels. Notably, TUG1 knockdown significantly decreased cardiac hypertrophy and reduced the fibrotic area, in vivo. To further investigate the underlying mechanism, miR-499-5p was predicted as the targeted TUG1 microRNA. The RT-qPCR and luciferase activity results confirmed that TUG1 negatively regulated miR-499-5p in cardiomyocytes. Furthermore, the overexpression of miR-499-5p abated the inhibitory effects of TUG1 silencing on high glucose-mediated cardiac hypertrophy, in vitro. Collectively, our study suggested that TUG1 knockdown attenuated DCM-induced cardiac hypertrophy and diastolic dysfunction by upregulating miR-499-5p. lncRNA TUG1 may be a novel potential target for DCM therapy.

Stat-3 signaling promotes cell proliferation and metastasis of gastric cancer through PDCD4 downregulation

The present study explored a new downstream regulator of Stat-3 signaling, miR-499-5p and its target gene programmed cell death 4 (PDCD4) in cell survival and metastasis of gastric cancer. Our results showed that miR-499-5p is significantly upregulated in human gastric cancer cell line SGC-7901. We further demonstrated that miR-499-5p promotes gastric cancer cell proliferation and invasion in vitro. Mechanistically, we demonstrated that upregulation of miR-499-5p expression associated with inhibition of PDCD4; STAT3 transcriptional activation by IL-6 is crucial for the upregulation of miR-499-5p expression. These results indicate that the STAT3-miR-499-5p-PDCD4 signaling axis plays an important role in gastric cancer progression and a potentially therapeutic target for gastric cancer treatment.

miR-499-5p Attenuates Mitochondrial Fission and Cell Apoptosis via p21 in Doxorubicin Cardiotoxicity

Doxorubicin (DOX) is a broad-spectrum anti-tumor drug, but its cardiotoxicity limits its clinical application. A better understanding of the molecular mechanisms underlying DOX cardiotoxicity will benefit clinical practice and remedy heart failure. Our present study observed that DOX caused cardiomyocyte (H9c2) apoptosis via the induction of abnormal mitochondrial fission. Notably, the expression levels of p21 increased in DOX-treated cardiomyocytes, and the silencing of p21 using siRNA greatly attenuated mitochondrial fission and apoptosis in cardiomyocytes. We also found that miR-499-5p could directly target p21 and attenuated DOX-induced mitochondrial fission and apoptosis. The role of the miR-499-5p-p21 axis in the prevention of DOX cardiotoxicity was also validated in the mice model. DOX treatment induced an upregulation of p21, which induced subsequent abnormal mitochondrial fission and myocardial apoptosis in mouse heart. Adenovirus-harboring miR-499-5p-overexpressing mice exhibited significantly reduced p21 expression, mitochondrial fission and myocardial apoptosis in hearts following DOX administration. The miR-499-5p-overexpressing mice also exhibited improved cardiomyocyte hypertrophy and cardiac function after DOX treatment. However, miR-499-5p was not involved in the DOX-induced apoptosis of cancer cells. Taken together, these findings reveal an emerging role of p21 in the regulation of mitochondrial fission program. miR-499-5p attenuated mitochondrial fission and DOX cardiotoxicity via the targeting of p21. These results provide new evidence for the miR-499-5p-p21 axis in the attenuation of DOX cardiotoxicity. The development of new therapeutic strategies based on the miR-499-5p-p21 axis is a promising path to overcome DOX cardiotoxicity as a chemotherapy for cancer treatment.

A polymorphism rs3746444 within the pre-miR-499 alters the maturation of miR-499-5p and its antiapoptotic function

microRNAs (miRNAs) are non‐coding RNAs that function as post‐transcriptional regulators of cardiac development and cardiovascular diseases. Single nucleotide polymorphisms (SNPs) in miRNA genes are a novel class of genetic variations in the human genome that confer the risk of cardiovascular diseases. Here, we identified a polymorphism A→G (rs3746444) in miR‐499 precursor (pre‐miR‐499) that affects the maturation of miR‐499‐5p and alters its antiapoptotic function by converting stable A‐U base pair to wobble G‐U base pair in pre‐miR‐499 secondary structure. Furthermore, our results showed that the concentrations of plasma miR‐499‐5p could be correlated with myocardial infarction (MI) and heart failure (HF) patients in comparison with control subjects and polymorphism rs3746444 in miR‐499 could influence its abundance in plasma. Finally, our results also showed that the variant of polymorphism in miR‐499 influenced the severity of the myocardial infarction significantly. This is the first report to highlight the biological significance of this polymorphism on the maturation of miR‐499‐5p and its antiapoptotic role during MI. These findings may pave a way to better understand the individual variability based on miRNA SNPs in heart diseases and may contribute to better treatment for disease severity on a personalized level.

MiR-499-5p protects cardiomyocytes against ischaemic injury via anti-apoptosis by targeting PDCD4

Recent studies have reported that miRNAs might play critical roles in acute myocardial infarction (AMI). The objective of this study is to investigate the role of miR-499-5p in AMI and its potential molecular mechanisms. The expression level of MiR-499-5p was remarkably decreased in the infarcted myocardial tissues and in the cultured neonatal rat cardiomyocytes induced by hypoxia. Overexpression or knockdown of miR-499-5p decreased or increased the apoptotic rates of cultured cardiomyocytes in vitro. In addition, ectopic overexpression of miR-499-5p in the rat AMI models with agomir reduced the myocardial infarct size through decreasing the cardiomyocytes apoptosis in the infarcted area of the rat hearts. PDCD4 (programmed cell death 4) was verified as a direct target of miR-499-5p by luciferase report assay, and ectopic overexpression or inhibition of miR-499-5p could inhibit or increase the PDCD4 expression at both the mRNA and protein levels. Furthermore, we found that ectopic overexpression of PDCD4 without miR-499-5p binding sites reversed miR-499-5p-mediated cardiomyocytes apoptosis. Together, these findings revealed the role of miR-499-5p in protecting the cardiomyocytes against apoptosis induced by AMI via its direct target PDCD4, which providing evidence for the miR-499-5p/PDCD4 pathway as a potential therapeutic target for patients with AMI.

MicroRNA-499-5p regulates porcine myofiber specification by controlling Sox6 expression

MicroRNAs (miRNAs) are a class of small non-coding RNAs that negatively regulate gene expression of target messenger RNAs (mRNAs) and miRNAs have been proven to play vital roles in skeletal muscle development. The miRNA-499-5p has been reported to be negatively related with the expression of Sox6, a critical transcription factor for the maintenance of fast-twitch skeletal muscle. In this study, we amplified a length of 2012-bp mRNA that contains a 1512-bp porcine Sox6 (pSox6) 3'UTR from skeletal muscle of a Duroc×Landrace×Yorkshire pig. By luciferase reporter assay we verified that pSox6 is a target of miR-499-5p. In extensor digitorum longus and Soleus muscles of pigs, the expression levels of miR-499-5p and pSox6 mRNA were also inversely correlated. Besides, overexpression of miR-499-5p in porcine satellite cells promoted the expression of MyHC I and MyHC IIa mRNA, along with a reduction of pSox6 mRNA. Taken together, these results indicate that miR-499-5p may facilitate the oxidative myofibers formation by downregulating pSox6 expression.