Cardiac Hypertrophy is Positively Regulated by MicroRNA‑24 in Rats

KLF9 aggravates the cardiomyocyte hypertrophy in hypertrophic obstructive cardiomyopathy through the lncRNA UCA1/p27 axis

Cardiac hypertrophy refers to an abnormal increase in the thickness of the heart muscle. Our study explores the role of Krüppel-like factor 9 (KLF9) in hypertrophic obstructive cardiomyopathy (HOCM)-induced cardiomyocyte hypertrophy, providing new targets for the treatment of HOCM. Cardiomyocytes were treated with isoproterenol (ISO). The levels of natriuretic peptide B (BNP)/natriuretic peptide A (ANP)/KLF9/long non-coding RNA urothelial carcinoma-associated 1 (lncRNA UCA1)/p27 were measured. Cell surface area and protein/DNA ratio were tested. The binding between KLF9 and the lncRNA UCA1 promoter and between zeste homologue 2 (EZH2) and lncRNA UCA1 was verified. The enrichment of histone H3 lysine 27 tri-methylation (H3K27me3) and EZH2 on the p27 promoter was analysed. ISO treatment increased KLF9 and lncRNA UCA1 expression and decreased p27 expression in cardiomyocytes. KLF9 knockdown inhibited ISO-induced cardiomyocyte hypertrophy, reduced ANP and BNP expression, and alleviated cardiomyocyte damage. KLF9 activated lncRNA UCA1 expression. LncRNA UCA1 recruited EZH2 to the p27 promoter region, increasing the enrichment of H3K27me3, thereby epigenetically suppressing p27 expression. LncRNA UCA1 overexpression or p27 downregulation reduced the protective effect of KLF9 downregulation on cardiomyocyte hypertrophy. In conclusion, KLF9 activates lncRNA UCA1 expression, and lncRNA UCA1 epigenetically suppresses p27 expression, thereby exacerbating cardiomyocyte hypertrophy in HOCM.

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.

Non-coding RNAs to regulate cardiomyocyte proliferation: A new trend in therapeutic cardiac regeneration

Cardiovascular diseases remain the leading cause of death worldwide, particularly ischemic heart disease (IHD). It is also classified as incurable given the irreversible damage it causes to cardiomyocytes. Thus, myocardial tissue rejuvenation following ischemia is one of the global primary research concerns for scientists. Interestingly, the mammalian heart thrives after an injury during the embryonic or neonatal period; however, this ability disappears with increasing age. Previous studies have found that specific non-coding (nc) RNAs play a pivotal role in this process. Hence, the review herein summarizes the research on cardiomyocyte regenerative medicine in recent years and sets forth the biological functions and mechanisms of the micro (mi)RNA, long non-coding (lnc)RNA, and circular (circ)RNA in the posttranscriptional regulation of cardiomyocytes. In addition, this review summarizes the roles of ncRNAs in specific species while enumerating potential therapeutic strategies for myocardial infarction.

Traditional Chinese Medicine Shen-Yuan-Dan (SYD) Improves Hypoxia-Induced Cardiomyocyte Apoptosis in Neonatal Rats by Upregulating miR-24/Bim Pathway

Background: Acute myocardial infarction (AMI) is the leading cause of malignant arrhythmia, heart failure, and sudden death. However, safe and effective drugs for the treatment of AMI are unavailable to date. The present study aimed to investigate the role of traditional Chinese medicine shen-yuan-dan (SYD) in hypoxia-induced cardiomyocyte apoptosis in neonatal rats. In addition, the study explored the possible mechanism through which SYD could reduce myocardial ischemia apoptosis and regulate the expression of the miR-24/Bim pathway. Methods: Hypoxia-induced neonatal rat cardiomyocytes were used for the experiments. These cardiomyocytes were transfected with an miR-24 mimic and an miR-24 inhibitor and then cocultured with SYD-containing serum. MTT and lactate dehydrogenase (LDH) assays, AnnexinV/PI double staining, flow cytometry, and TUNEL staining were used to determine the cell viability and apoptosis under hypoxic conditions. Furthermore, the expression level of Bim in the hypoxia-induced cardiomyocytes was determined through western blotting and quantitative real-time polymerase chain reaction. Results: After 48 h of hypoxia, LDH and creatine phosphokinase (CPK) activities increased, cell viability decreased, and miR-24 expression upregulated in the cardiomyocytes. SYD alleviated hypoxia-induced cardiomyocyte injury, decreased LDH and CPK activities, increased cell viability, and reduced apoptosis in the neonatal rat cardiomyocytes. Moreover, SYD could upregulate miR-24 expression and downregulate Bim expression. Upregulation of miR-24 expression significantly enhanced the effect of SYD, thereby improving myocardial cell apoptosis. Dual-luciferase reporter assay and western blot analysis confirmed that Bim was a direct target of miR-24. Conclusion: SYD treatment reduces hypoxia-induced myocardial apoptosis by upregulating miR-24 expression. This study provides new insights into the molecular mechanism underlying the therapeutic potential of SYD in promoting the recovery of myocardial function and delaying the incidence of heart failure.

The Role of METTL3-Mediated N6-Methyladenosine (m6A) of JPH2 mRNA in Cyclophosphamide-Induced Cardiotoxicity

Cyclophosphamide (CYP)-induced cardiotoxicity is a common side effect of cancer treatment. Although it has received significant attention, the related mechanisms of CYP-induced cardiotoxicity remain largely unknown. In this study, we used cell and animal models to investigate the effect of CYP on cardiomyocytes. Our data demonstrated that CYP-induced a prolonged cardiac QT interval and electromechanical coupling time courses accompanied by JPH2 downregulation. Moreover, N6-methyladenosine (m6A) methylation sequencing and RNA sequencing suggested that CYP induced cardiotoxicity by dysregulating calcium signaling. Importantly, our results demonstrated that CYP induced an increase in the m6A level of JPH2 mRNA by upregulating methyltransferases METTL3, leading to the reduction of JPH2 expression levels, as well as increased field potential duration and action potential duration in cardiomyocytes. Our results revealed a novel mechanism for m6A methylation-dependent regulation of JPH2, which provides new strategies for the treatment and prevention of CYP-induced cardiotoxicity.

Role of miR-24 in Multiple Endocrine Neoplasia Type 1: A Potential Target for Molecular Therapy

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited multiple cancer syndrome of neuroendocrine tissues. Tumors are caused by an inherited germinal heterozygote inactivating mutation of the MEN1 tumor suppressor gene, followed by a somatic loss of heterozygosity (LOH) of the MEN1 gene in target neuroendocrine cells, mainly at parathyroids, pancreas islets, and anterior pituitary. Over 1500 different germline and somatic mutations of the MEN1 gene have been identified, but the syndrome is completely missing a direct genotype-phenotype correlation, thus supporting the hypothesis that exogenous and endogenous factors, other than MEN1 specific mutation, are involved in MEN1 tumorigenesis and definition of individual clinical phenotype. Epigenetic factors, such as microRNAs (miRNAs), are strongly suspected to have a role in MEN1 tumor initiation and development. Recently, a direct autoregulatory network between miR-24, MEN1 mRNA, and menin was demonstrated in parathyroids and endocrine pancreas, showing a miR-24-induced silencing of menin expression that could have a key role in initiation of tumors in MEN1-target neuroendocrine cells. Here, we review the current knowledge on the post-transcriptional regulation of MEN1 and menin expression by miR-24, and its possible direct role in MEN1 syndrome, describing the possibility and the potential approaches to target and silence this miRNA, to permit the correct expression of the wild type menin, and thereby prevent the development of cancers in the target tissues.

G6PD, bond by miR-24, regulates mitochondrial dysfunction and oxidative stress in phenylephrine-induced hypertrophic cardiomyocytes

AIMS

Pathological cardiac hypertrophy (CH) is one of the main risk factors for heart failure and cardiac death. Mitochondrial dysfunction and oxidative stress often occur in hypertrophic cardiomyocytes. It was recently proposed that deficiency or decreased activity of glucose-6-phosphate dehydrogenase (G6PD) may be related to the development of CH. This study aimed to investigate the expression of G6PD in CH and its regulatory role in mitochondrial dysfunction and oxidative stress of CH cells.

MAIN METHODS

Phenylephrine (PE) was used to create an in vitro model of CH. Using RT-qPCR and western blotting, the expression levels of target mRNAs and proteins were measured. ELISA assays and commercial kits based on spectrophotometry or colorimetry were used to measure mitochondrial function and oxidative stress. TargetScan and luciferase reporter gene assays were utilized for combination prediction and validation. CCK-8 and TUNEL kit were used to determine cell viability and apoptosis.

KEY FINDINGS

The results showed that G6PD overexpression attenuated the decreases of mitochondrial respiration, ATP, ATP synthetase and mitochondrial membrane potential induced by PE, as well as the increases of LDH release and apoptosis. Besides, PE elevated ROS activity, NO and MDA contents, and reduced SOD, CAT levels and cell viability. These effects were hindered by G6PD overexpression. MiR-24 was found to directly bind to G6PD at the motif of CUGAGCC and regulated its expression, furtherly, influenced the G6PD-mediated mitochondrial dysfunction and oxidative stress of CH cells.

SIGNIFICANCE

Generally, our study demonstrated that miR-24/G6PD regulates mitochondrial dysfunction and oxidative stress in CH cells, representing a new sight for CH therapy.

MicroRNA-200a-3p Is a Positive Regulator in Cardiac Hypertrophy Through Directly Targeting WDR1 as Well as Modulating PTEN/PI3K/AKT/CREB/WDR1 Signaling

Cardiac hypertrophy is an adaptive expansion of the myocardium due to the overloaded stress of heart. Recently, emerging studies have drawn a conclusion that microRNAs (miRNAs) are involved in myocardial hypertrophy and even heart failure. To figure out the role of microRNA-200a-3p (miR-200a-3p) in cardiac hypertrophy, the in vitro cardiac hypertrophy model was established in H9c2 cells using angiotensin II (Ang-II) as previously described. First of all, we observed a significant increase of miR-200a-3p expression in Ang-II-induced hypertrophic H9c2 cells. Moreover, inhibition of miR-200a-3p dramatically reversed the Ang-II-upregulated expression of hypertrophic markers (atrial natriuretic peptide, brain natriuretic peptide, and β-MHC) and the expanded cell surface area in H9c2 cells. In addition, our results indicated that miR-200a-3p directly targeted both WDR1 and phosphatase and tensin homolog (PTEN). In this regard, miR-200a-3p further activated PI3K/AKT/CREB pathway so as to intensify its negative regulation on WDR1. At length, WDR1 silence, PTEN inhibitor, and PI3K activator recovered the repressive effect of miR-200a-3p suppression on the development of cardiac hypertrophy. Jointly, our study suggested that miR-200a-3p facilitated cardiac hypertrophy by not only directly targeting WDR1 but also through modulating PTEN/PI3K/AKT/CREB/WDR1 signaling, therefore proving novel downstream molecular pathway of miR-200a-3p in cardiac hypertrophy.

MicroRNAs in Cardiac Hypertrophy

Like other organs, the heart undergoes normal adaptive remodeling, such as cardiac hypertrophy, with age. This remodeling, however, is intensified under stress and pathological conditions. Cardiac remodeling could be beneficial for a short period of time, to maintain a normal cardiac output in times of need; however, chronic cardiac hypertrophy may lead to heart failure and death. MicroRNAs (miRNAs) are known to have a role in the regulation of cardiac hypertrophy. This paper reviews recent advances in the field of miRNAs and cardiac hypertrophy, highlighting the latest findings for targeted genes and involved signaling pathways. By targeting pro-hypertrophic genes and signaling pathways, some of these miRNAs alleviate cardiac hypertrophy, while others enhance it. Therefore, miRNAs represent very promising potential pharmacotherapeutic targets for the management and treatment of cardiac hypertrophy.

LncRNA TUG1 promotes cells proliferation and inhibits cells apoptosis through regulating AURKA in epithelial ovarian cancer cells

This study aimed to assess the effect of long noncoding RNAs (lncRNAs) taurine-upregulated gene 1 (TUG1) on cells proliferation and apoptosis as well as its targeting genes in epithelial ovarian cancer (EOC) cells.Blank mimic, lncRNA TUG1 mimic, blank inhibitor, and lncRNA TUG1 inhibitor plasmids were transfected into SK-OV-3 (SKOV3) cells. Rescue experiment was performed by the transfection of lncRNA TUG1 inhibitor and Aurora kinase A (AURKA) mimic plasmids into SKOV3 cells. Cell counting kit-8 (CKK-8), annexin V-FITC (AV)-propidium iodide (PI) (AV-PI), quantitative polymerase chain reaction (qPCR), and western blot assays were performed to detect cells proliferation, apoptosis, RNA expression, and protein expression respectively.Cells proliferation was increased in lncRNA TUG1 mimic group and decreased in lncRNA TUG1 inhibitor group than normal control (NC) groups. Cells apoptosis rate was repressed after treatment with lncRNA TUG1 mimic and promoted after treatment with lncRNA TUG1 inhibitor. AURKA expression but not CLDN3, SERPINE1, or ETS1 expression was adversely regulated by lncRNA TUG1 mimic and inhibitor. After transferring lncRNA TUG1 (-) and AURKA (+) plasmids, cells proliferation was increased, while cells apoptosis rate was decreased in AURKA mimic (+)/lncRNA TUG1 inhibitor (-) group than NC (+)/lncRNA TUG1 (-) group, which suggested lncRNA TUG1 regulated cells proliferation and cells apoptosis through targeting AURKA.LncRNA TUG1 promotes cells proliferation and inhibits cells apoptosis through regulating AURKA in EOC cells.