Adiponectin Upregulates MiR-133a in Cardiac Hypertrophy through AMPK Activation and Reduced ERK1/2 Phosphorylation

LDHA contributes to nicotine induced cardiac fibrosis through autophagy flux impairment

Cardiac fibrosis is a typical feature of cardiac pathological remodeling, which is associated with adverse clinical outcomes and has no effective therapy. Nicotine is an important risk factor for cardiac fibrosis, yet its underlying molecular mechanism remains poorly understood. This study aimed to identify its potential molecular mechanism in nicotine-induced cardiac fibrosis. Our results showed nicotine exposure led to the proliferation and transformation of cardiac fibroblasts (CFs) into myofibroblasts (MFs) by impairing autophagy flux. Through the use of drug affinity responsive target stability (DARTS) assay, cellular thermal shift assay (CETSA), and surface plasmon resonance (SPR) technology, it was discovered that nicotine directly increased the stability and protein levels of lactate dehydrogenase A (LDHA) by binding to it. Nicotine treatment impaired autophagy flux by regulating the AMPK/mTOR signaling pathway, impeding the nuclear translocation of transcription factor EB (TFEB), and reducing the activity of cathepsin B (CTSB). In vivo, nicotine treatment exacerbated cardiac fibrosis induced in spontaneously hypertensive rats (SHR) and worsened cardiac function. Interestingly, the absence of LDHA reversed these effects both in vitro and in vivo. Our study identified LDHA as a novel nicotine-binding protein that plays a crucial role in mediating cardiac fibrosis by blocking autophagy flux. The findings suggest that LDHA could potentially serve as a promising target for the treatment of cardiac fibrosis.

Tamoxifen induced cardiac damage via the IL-6/p-STAT3/PGC-1α pathway

Tamoxifen (TAM) is an effective anticancer drug for breast and ovarian cancer. However, increased risk of cardiotoxicity is a long-term clinical problem associated with TAM, while the underlying mechanisms remain unclear. Here, we performed experiments in cardiomyocytes and tumor-bearing or nontumor-bearing mice, and demonstrated that TAM induced cardiac injury via the IL-6/p-STAT3/PGC-1α/IL-6 feedback loop, which is responsible for reactive oxygen species (ROS) accumulation. Compared with non-tumor bearing mice, tumor-bearing mice showed stronger cardiac toxicity after TAM injection, although there was no significant difference. In vitro experiments demonstrated STAT3 phosphorylation inhibitor can increase PGC-1α expression and protect cardiomyocyte via decreasing ROS. Since tumor has higher STAT3 phosphorylation and IL-6 expression level, our research results indicated combining TAM and STAT3 inhibitor might be an effective treatment strategy which can provide both tumor killing and cardioprotective function. Further in vivo research is needed to fully elucidate the effect and mechanisms of the combination therapy of TAM and STAT3 inhibitor.

Adiponectin, the adiponectin paradox, and Alzheimer's Disease: Is this association biologically plausible?

Dementia, especially Alzheimer's Disease (AD) and vascular dementia, is a major public health problem that continues to expand in both economically emerging and hegemonic countries. In 2017, the World Alzheimer Report estimated that over 50 million people were living with dementia globally. Metabolic dysfunctions of brain structures such as the hippocampus and cerebral cortex have been implicated as risk factors for dementia. Several well-defined metabolic risk factors for AD include visceral obesity, chronic inflammation, peripheral and brain insulin resistance, type 2 diabetes mellitus (T2DM), hypercholesterolemia, and others. In this review, we describe the relationship between the dysmetabolic mechanisms, although still unknown, and dementia, particularly AD. Adiponectin (ADPN), the most abundant circulating adipocytokine, acts as a protagonist in the metabolic dysfunction associated with AD, with unexpected and intriguing dual biological functions. This contradictory role of ADPN has been termed the adiponectin paradox. Some evidence suggests that the adiponectin paradox is important in amyloidogenic evolvability in AD. We present cumulative evidence showing that AD and T2DM share many common features. We also review the mechanistic pathways involving brain insulin resistance. We discuss the importance of the evolvability of amyloidogenic proteins (APs), defined as the capacity of a system for adaptive evolution. Finally, we describe potential therapeutic strategies in AD, based on the adiponectin paradox.

Role of Adiponectin in Cardiovascular Diseases Related to Glucose and Lipid Metabolism Disorders

Lifestyle changes have led to increased incidence of cardiovascular disease (CVD); therefore, potential targets against CVD should be explored to mitigate its risks. Adiponectin (APN), an adipokine secreted by adipose tissue, has numerous beneficial effects against CVD related to glucose and lipid metabolism disorders, including regulation of glucose and lipid metabolism, increasing insulin sensitivity, reduction of oxidative stress and inflammation, protection of myocardial cells, and improvement in endothelial cell function. These effects demonstrate the anti-atherosclerotic and antihypertensive properties of APN, which could aid in improving myocardial hypertrophy, and reducing myocardial ischemia/reperfusion (MI/R) injury and myocardial infarction. APN can also be used for diagnosing and predicting heart failure. This review summarizes and discusses the role of APN in the treatment of CVD related to glucose and lipid metabolism disorders, and explores future APN research directions and clinical application prospects. Future studies should elucidate the signaling pathway network of APN cardiovascular protective effects, which will facilitate clinical trials targeting APN for CVD treatment in a clinical setting.

Natural AMPK Activators in Cardiovascular Disease Prevention

Cardiovascular diseases (CVD), as a life-threatening global disease, is receiving worldwide attention. Seeking novel therapeutic strategies and agents is of utmost importance to curb CVD. AMP-activated protein kinase (AMPK) activators derived from natural products are promising agents for cardiovascular drug development owning to regulatory effects on physiological processes and diverse cardiometabolic disorders. In the past decade, different therapeutic agents from natural products and herbal medicines have been explored as good templates of AMPK activators. Hereby, we overviewed the role of AMPK signaling in the cardiovascular system, as well as evidence implicating AMPK activators as potential therapeutic tools. In the present review, efforts have been made to compile and update relevant information from both preclinical and clinical studies, which investigated the role of natural products as AMPK activators in cardiovascular therapeutics.

Nicotine Causes Mitochondrial Dynamics Imbalance and Apoptosis Through ROS Mediated Mitophagy Impairment in Cardiomyocytes

Nicotine contained in traditional cigarettes, hookahs, and e-cigarettes is an important risk factor for cardiovascular disease. Our previous study showed that macroautophagic flux impairment occurred under nicotine stimulation. However, whether nicotine influences mitochondrial dynamics in neonatal rat ventricular myocytes (NRVMs) is unclear. The purpose of this study was to explore the effects and potential mechanism of nicotine on mitophagy, mitochondrial dynamics, apoptosis, and the relationship between these processes in NRVMs. Our results showed that nicotine exposure increased mitochondria-derived superoxide production, decreased mitochondrial membrane potential, and impaired PINK1/Parkin-mediated mitophagic flux in NRVMs. Interestingly, nicotine significantly promoted dynamin-related protein 1 (Drp1)-mediated mitochondrial fission and suppressed mitofusin (MFN)-mediated fusion, which was also observed in the bafilomycin A1-treated group. These results suggest that mitophagic flux impairment may contribute to Drp-1-mediated mitochondrial fission. Finally, nicotine caused excessive mitochondrial fission and contributed to apoptosis, which could be alleviated by mdivi-1, an inhibitor of Drp1. In addition to CTSB, as we previously reported, the enzyme activity of cathepsin L (CTSL) was also decreased in lysosomes after stimulation with nicotine, which may be the main cause of the hindered mitophagic flux induced by nicotine in NRVMs. Pretreatment with Torin 1, which is an inhibitor of mTOR, activated CTSL and ameliorated nicotine-induced mTOR activation and mitophagy impairment, decreased mitochondria-derived superoxide production, and blunted mitochondrial fission and apoptosis. Pretreatment with the ROS scavenger N-acetyl-cysteine (NAC) or inhibitors of p38 and JNK, which could also alleviate mitophagy impairment, exhibited similar effects as Torin1 on mitochondria. Taken together, our study demonstrated that nicotine treatment may lead to an increase in Drp1-mediated mitochondrial fission by blocking mitophagic flux by weakening the enzyme activity of CTSL and activating the ROS/p38/JNK signaling pathway. Excessive mitochondrial fission induced by nicotine ultimately leads to apoptosis. Torin1 restored the decreased CTSL enzyme activity by removing excessive ROS and alleviated the effects of nicotine on mitophagic flux, mitochondrial dynamics, and apoptosis. These results may provide new evidence on the relationship between mitophagic flux and mitochondrial dynamics and new perspectives on nicotine’s effects on mitochondrial dynamics in cardiomyocytes.

The Impact of microRNAs in Renin-Angiotensin-System-Induced Cardiac Remodelling

Current knowledge on the renin-angiotensin system (RAS) indicates its central role in the pathogenesis of cardiovascular remodelling via both hemodynamic alterations and direct growth and the proliferation effects of angiotensin II or aldosterone resulting in the hypertrophy of cardiomyocytes, the proliferation of fibroblasts, and inflammatory immune cell activation. The noncoding regulatory microRNAs has recently emerged as a completely novel approach to the study of the RAS. A growing number of microRNAs serve as mediators and/or regulators of RAS-induced cardiac remodelling by directly targeting RAS enzymes, receptors, signalling molecules, or inhibitors of signalling pathways. Specifically, microRNAs that directly modulate pro-hypertrophic, pro-fibrotic and pro-inflammatory signalling initiated by angiotensin II receptor type 1 (AT1R) stimulation are of particular relevance in mediating the cardiovascular effects of the RAS. The aim of this review is to summarize the current knowledge in the field that is still in the early stage of preclinical investigation with occasionally conflicting reports. Understanding the big picture of microRNAs not only aids in the improved understanding of cardiac response to injury but also leads to better therapeutic strategies utilizing microRNAs as biomarkers, therapeutic agents and pharmacological targets.

Tissue-specific role and associated downstream signaling pathways of adiponectin

According to the World Health Organization, metabolic syndrome (MetS) can be defined as a pathological condition characterized by abdominal obesity, insulin resistance, hypertension, and hyperlipidemia. The incidence of MetS keeps rising, as at least 35% of the USA population suffers from MetS. One of the worst comorbidities of metabolic syndrome are cardiovascular diseases that significantly amplifies the mortality associated with this syndrome. There is an urgent need to understand the pathophysiology of MetS to find novel diagnosis, treatment and management to mitigate the MetS and associated complications. Altered circulatory adiponectin levels have been implicated in MetS. Adiponectin has numerous biologic functions including antioxidative, anti-nitrative, anti-inflammatory, and cardioprotective effects. Being a pleiotropic hormone of multiple tissues, tissue-specific key signaling pathways of adiponectin will help finding specific target/s to blunt the pathophysiology of metabolic syndrome and associated disorders. The purpose of this review is to elucidate tissue-specific signaling pathways of adiponectin and possibly identify potential therapeutic targets for MetS as well as to evaluate the potential of adiponectin as a biomarker/therapeutic option in MetS.

Comprehensive Analysis of Genes Associated With Sudden Infant Death Syndrome

Background: Sudden infant death syndrome (SIDS) is a tragic incident which remains a mystery even after post-mortem investigation and thorough researches. Methods: This comprehensive review is based on the genes reported in the molecular autopsy studies conducted on SIDS so far. A total of 20 original studies and 7 case reports were identified and included in this analysis. The genes identified in children or adults were not included. Most of the genes reported in these studies belonged to cardiac channel and cardiomyopathy. Cardiac channel genes in SIDS were scrutinized for further analysis. Results: After screening and removing the duplicates, 42 unique genes were extracted. When the location of these genes was assessed, it was observed that most of these belonged to Chromosomes 11, 1 and 3 in sequential manner. The pathway analysis shows that these genes are involved in the regulation of heart rate, action potential, cardiac muscle cell contraction and heart contraction. The protein-protein interaction network was also very big and highly interactive. SCN5A, CAV3, ALG10B, AKAP9 and many more were mainly found in these cases and were regulated by many transcription factors such as MYOG C2C1 and CBX3 HCT11. Micro RNA, "hsa-miR-133a-3p" was found to be prevalent in the targeted genes. Conclusions: Molecular and computational approaches are a step forward toward exploration of these sad demises. It is so far a new arena but seems promising to dig out the genetic cause of SIDS in the years to come.

Cilostazol alleviate nicotine induced cardiomyocytes hypertrophy through modulation of autophagy by CTSB/ROS/p38MAPK/JNK feedback loop

Nicotine is proved to be an important factor for cardiac hypertrophy. Autophagy is important cell recycling system involved in the regulation of cardiac hypertrophy. Cilostazol, which is often used in the management of peripheral vascular disease. However, the effects of cilostazol on nicotine induced autophagy and cardiac hypertrophy are unclear. Here, we aim to determine the role and molecular mechanism of cilostazol in alleviating nicotine-induced cardiomyocytes hypertrophy through modulating autophagy and the underlying mechanisms. Our results clarified that nicotine stimulation caused cardiomyocytes hypertrophy and autophagy flux impairment significantly in neonatal rat ventricular myocytes (NRVMs), which were evidenced by augments of LC3-II and p62 levels, and impaired autophagosomes clearance. Interestingly, cathepsin B (CTSB) activity decreased dramatically after stimulation with nicotine in NRVMs, which was crucial for substrate degradation in the late stage of autophagy process, and cilostazol could reverse this effect dramatically. Intracellular ROS levels were increased significantly after nicotine exposure. Meanwhile, p38MAPK and JNK were activated after nicotine treatment. By using ROS scavenger N-acetyl-cysteine (NAC) could reverse the effects of nicotine by down-regulation the phosphorylation of p38MAPK and JNK pathways, and pretreatment of specific inhibitors of p38MAPK and JNK could restore the autophagy impairment and cardiomyocytes hypertrophy induced by nicotine. Moreover, CTSB activity of lysosome regained after the treatment with cilostazol. Cilostazol also inhibited the ROS accumulation and the activation of p38MAPK and JNK, which providing novel connection between lysosome CTSB and ROS/p38MAPK/JNK related oxidative stress pathway. This is the first demonstration that cilostazol could alleviate nicotine induced cardiomyocytes hypertrophy through restoration of autophagy flux by activation of CTSB and inhibiting ROS/p38/JNK pathway, exhibiting a feedback loop on regulation of autophagy and cardiomyocytes hypertrophy.

MiR-103 inhibiting cardiac hypertrophy through inactivation of myocardial cell autophagy via targeting TRPV3 channel in rat hearts

Cardiac hypertrophy is a common pathological change frequently accompanied by chronic hypertension and myocardial infarction. Nevertheless, the pathophysiological mechanisms of cardiac hypertrophy have never been elucidated. Recent studies indicated that miR-103 expression was significantly decreased in heart failure patients. However, less is known about the role of miR-103 in cardiac hypertrophy. The present study was designed to investigate the relationship between miR-103 and the mechanism of pressure overload-induced cardiac hypertrophy. TRPV3 protein, cardiac hypertrophy marker proteins (BNP and β-MHC) and autophagy associated proteins (Beclin-1 and LC3-II) were up-regulated, as well as, miR-103 expression and autophagy associated proteins (p62) were down-regulated in cardiac hypertrophy models in vivo and in vitro respectively. Further results indicated that silencing TRPV3 or forcing overexpression of miR-103 could dramatically inhibit cell surface area, relative fluorescence intensity of Ca2+ signal and the expressions of BNP, β-MHC, Beclin-1 and LC3-II, but promote p62 expression. Moreover, TRPV3 protein was decreased in neonatal rat ventricular myocyte transfected with miR-103, but increased by AMO-103. Co-transfection of the miR-103 with the luciferase reporter vector into HEK293 cells caused a sharp decrease in luciferase activity compared with transfection of the luciferase vector alone. The miR-103-induced depression of luciferase activity was rescued by an AMO-103. These findings suggested that TRPV3 was a direct target of miR-103. In conclusion, miR-103 could attenuate cardiomyocyte hypertrophy partly by reducing cardiac autophagy activity through the targeted inhibition of TRPV3 signalling in the pressure-overloaded rat hearts.

The MicroRNA Family Both in Normal Development and in Different Diseases: The miR-17-92 Cluster

An increasing number of research studies over recent years have focused on the function of microRNA (miRNA) molecules which have unique characteristics in terms of structure and function. They represent a class of endogenous noncoding single-strand small molecules. An abundance of miRNA clusters has been found in the genomes of various organisms often located in a polycistron. The miR-17-92 family is among the most famous miRNAs and has been identified as an oncogene. The functions of this cluster, together with the seven individual molecules that it comprises, are most related to cancers, so it would not be surprising that they are considered to have involvement in the development of tumors. The miR-17-92 cluster is therefore expected not only to be a tumor marker, but also to perform an important role in the early diagnosis of those diseases and possibly also be a target for tumor biotherapy. The miR-17-92 cluster affects the development of disease by regulating many related cellular processes and multiple target genes. Interestingly, it also has important roles that cannot be ignored in disease of the nervous system and circulation and modulates the growth and development of bone. Therefore, it provides new opportunities for disease prevention, clinical diagnosis, prognosis, and targeted therapy. Here we review the role of the miR-17-92 cluster that has received little attention in relation to neurological diseases, cardiac diseases, and the development of bone and tumors.

Adiponectin attenuates lipopolysaccharide-induced cell injury of H9c2 cells by regulating AMPK pathway

Adiponectin, an adipokine synthesized and secreted majorly by adipose tissue, is reported to exert cardioprotective properties via anti-inflammation and antiapoptosis. Lipopolysaccharide (LPS) is a common inflammation and apoptosis inducer of cardiomyocytes. However, few studies have reported the roles of adiponectin on LPS-induced inflammation as well as apoptosis of H9c2 cells, and the possible mechanisms of these effects. In the present study, we found that adiponectin significantly relieved LPS-induced cytotoxicity including decreased viability and elevated LDH release, inhibited LPS-triggered inflammation, which is evidenced by increases in release of TNF-α, IL-1β as well as IL-6, and attenuated the enhanced rates of apoptotic cells as well as increased caspase-3 activity caused by LPS in H9c2 cells. In addition, our data demonstrated that adiponectin upregulated AMP-activated protein kinase (AMPK) activation of H9c2 cells with or without LPS administration. Moreover, we found that blocking AMPK pathway by compound c attenuated the protective effects of adiponectin against the cytotoxicity, inflammatory response, and apoptosis of H9c2 cells resulted from LPS. Our observations bring novel insights for understanding the mediatory role of AMPK pathway implicated in the protective effects of adiponectin against LPS-induced cardiotoxicity.

Adipokines Regulate the Expression of Tumor-Relevant MicroRNAs

BACKGROUND

Increasing prevalence of obesity requires the investigation of respective comorbidities, including tumor diseases like colorectal, renal, post-menopausal breast, prostate cancer, and leukemia. To date, molecular mechanisms of the malignant transformation of these peripheral tissues induced by obesity remain unclear. Adipose tissue secretes factors with hormone-like functions, the adipokines, and is therefore categorized as an endocrine organ. Current research demonstrates the ability of adipose tissue to alter DNA methylation and gene expression in peripheral tissues, probably affecting microRNA (miR) expression.

METHODS

Literature was analyzed for adipokine-regulated miRs. Many of these adipokine upregulated or downregulated miRs exert either oncogenic or anti-tumoral potential.

RESULTS

The three selected and analyzed adipokines, adiponectin, leptin, and resistin, induce more strongly oncogenic miRs and simultaneously reduce anti-tumoral miRs than vice versa. This effect is not only true for the pure number of regulated miRs, it is also the case by consideration of the abundance of the respective miR expression based on actual data sets derived from next-generation sequencing.

CONCLUSION

The link of obesity and cancer is analyzed under the aspect of adipokine-regulated miRs. At the same time the impact of miR abundance is considered as a regulatory variable. This context offers new strategies for tumor therapy and diagnostics.

Examining the Potential of Developing and Implementing Use of Adiponectin-Targeted Therapeutics for Metabolic and Cardiovascular Diseases

Cardiometabolic diseases encompass those affecting the heart and vasculature as well as other metabolic problems, such as insulin resistance, diabetes, and non-alcoholic fatty liver disease. These diseases tend to have common risk factors, one of which is impaired adiponectin action. This may be due to reduced bioavailability of the hormone or resistance to its effects on target tissues. A strong negative correlation between adiponectin levels and cardiometabolic diseases has been well-documented and research shown that adiponectin has cardioprotective, insulin sensitizing and direct beneficial metabolic effects. Thus, therapeutic approaches to enhance adiponectin action are widely considered to be desirable. The complexity of adiponectin structure and function has so far made progress in this area less than ideal. In this article we will review the effects and mechanism of action of adiponectin on cardiometabolic tissues, identify scenarios where enhancing adiponectin action would be of clinical value and finally discuss approaches via which this can be achieved.

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

miR-876-3p regulates glucose homeostasis and insulin sensitivity by targeting adiponectin

miRNA has been known to regulate diverse cellular and molecular functions. In the earlier study, we have reported that adipocytes differentiated from human mesenchymal stem cells (hMSC) on 72-h chronic insulin (CI) treatment exhibit insulin resistance (IR). Present study has further explored above model to investigate the role of early expressed miRNAs within human adipocytes to modulate differential adipokine expression as observed during IR. Our results highlight that miR-876-3p regulate glucose homeostasis and its dysregulation leads to IR. We found that miR-876-3p level is a critical determinant of adiponectin expression by virtue of its target within adiponectin 3′UTR. Regulatory effect of miR-876-3p impacts crosstalk between adiponectin and insulin signaling. Rosiglitazone treatment in CI-induced IR adipocytes drastically reduced miR-876-3p expression and increased adiponectin level. In line with this, lentiviral-mediated inhibition of miR-876-3p expression ameliorated CI and high-fat diet (HFD)-induced IR in adipocytes differentiated from hMSC and C57BL/6 mice, respectively. Our findings thus suggest that modulating miR-876-3p expression could provide novel opportunities for therapeutic intervention of obesity-associated metabolic syndrome.

Emerging Role of mTOR Signaling-Related miRNAs in Cardiovascular Diseases

Mechanistic/mammalian target of rapamycin (mTOR), an atypical serine/threonine kinase of the phosphoinositide 3-kinase- (PI3K-) related kinase family, elicits a vital role in diverse cellular processes, including cellular growth, proliferation, survival, protein synthesis, autophagy, and metabolism. In the cardiovascular system, the mTOR signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of both physiological and pathological processes. MicroRNAs (miRs), a class of short noncoding RNA, are an emerging intricate posttranscriptional modulator of critical gene expression for the development and maintenance of homeostasis across a wide array of tissues, including the cardiovascular system. Over the last decade, numerous studies have revealed an interplay between miRNAs and the mTOR signaling circuit in the different cardiovascular pathophysiology, like myocardial infarction, hypertrophy, fibrosis, heart failure, arrhythmia, inflammation, and atherosclerosis. In this review, we provide a comprehensive state of the current knowledge regarding the mechanisms of interactions between the mTOR signaling pathway and miRs. We have also highlighted the latest advances on mTOR-targeted therapy in clinical trials and the new perspective therapeutic strategies with mTOR-targeting miRs in cardiovascular diseases.

miR-133: A Suppressor of Cardiac Remodeling?

Cardiac remodeling, which is characterized by mechanical and electrical remodeling, is a significant pathophysiological process involved in almost all forms of heart diseases. MicroRNAs (miRNAs) are a group of non-coding RNAs of 20–25 nucleotides in length that primarily regulate gene expression by promoting mRNA degradation or post-transcriptional repression in a sequence-specific manner. Three miR-133 genes have been identified in the human genome, miR-133a-1, miR-133a-2, and miR-133b, which are located on chromosomes 18, 20, and 6, respectively. These miRNAs are mainly expressed in muscle tissues and appear to repress the expression of non-muscle genes. Based on accumulating evidence, miR-133 participates in the proliferation, differentiation, survival, hypertrophic growth, and electrical conduction of cardiac cells, which are essential for cardiac fibrosis, cardiac hypertrophy, and arrhythmia. Nevertheless, the roles of miR-133 in cardiac remodeling are ambiguous, and the mechanisms are also sophisticated, involving many target genes and signaling pathways, such as RhoA, MAPK, TGFβ/Smad, and PI3K/Akt. Therefore, in this review, we summarize the critical roles of miR-133 and its potential mechanisms in cardiac remodeling.

Utility of miR‑133a‑3p as a diagnostic indicator for hepatocellular carcinoma: An investigation combined with GEO, TCGA, meta‑analysis and bioinformatics

Increasing evidence has demonstrated that microRNA (miR)‑133a‑3p is an important regulator of hepatocellular carcinoma (HCC). In the present study, the diagnostic role of miR‑133a‑3p in HCC, and the potential functional pathways, were both explored based on publicly available data. Eligible microarray datasets were collected from NCBI Gene Expression Omnibus (GEO) database and ArrayExpress database. The data related to HCC and matched adjacent normal tissues were also downloaded from The Cancer Genome Atlas (TCGA). Published studies reporting the association between miR‑133a‑3p expression and HCC were reviewed from multiple databases. By combining the data derived from three sources (GEO, TCGA and published studies), the authors analyzed the comprehensive relationship between miR‑133a‑3p expression and clinicopathological features of HCC. Eventually, putative targets of miR‑133a‑3p in HCC were selected for further bioinformatics prediction. A total of eight published microarray datasets were gathered, and the pooled results demonstrated that the expression of miR‑133a‑3p in the tumor group was lower than that in normal groups [standardized mean difference (SMD)=‑0.54; 95% confidence interval (CI), ‑0.74 to ‑0.35; P<0.001]. Consistently, the level of miR‑133a‑1 in HCC was reduced markedly compared to normal tissues (P<0.001) based on TCGA data, and the AUC value of low miR‑133a‑1 expression for HCC diagnosis was 0.670 (P<0.001). Furthermore, the combined SMD of all datasets (GEO, TCGA and literature) suggested that significant difference was observed between the HCC group and the normal control group, and lower miR‑133a‑3p expression in HCC group was noted (SMD=‑0.69; 95% CI, ‑1.10 to ‑0.29; P=0.001). In addition, the authors discovered five key genes of the calcium signaling pathway (NOS1, ADRA1A, ADRA1B, ADRA1D and TBXA2R) that may probably be targeted by miR‑133a‑3p in HCC. The study reveals that miR‑133a‑3p may function as a tumor suppressor in HCC. The prospective novel pathways and key genes of miR‑133a‑3p could offer potential biomarkers for HCC; however, the predictions require further confirmation.

AMPK and cardiac remodelling

Cardiac remodelling is generally accepted as a critical process in the progression of heart failure. Myocyte hypertrophy, inflammatory responses and cardiac fibrosis are the main pathological changes associated with cardiac remodelling. AMP-activated protein kinase (AMPK) is known as an energy sensor and a regulator of cardiac metabolism under normal and ischaemic conditions. Additionally, AMPK has been shown to play roles in cardiac remodelling extending well beyond metabolic regulation. In this review, we discuss the currently defined roles of AMPK in cardiac remodelling and summarize the effects of AMPK on cardiac hypertrophy, inflammatory responses and fibrosis and the molecular mechanisms underlying these effects. In addition, we discuss some pharmacological activators of AMPK that are promising treatments for cardiac remodelling.

miR-125a, miR-139 and miR-324 contribute to Urocortin protection against myocardial ischemia-reperfusion injury

Urocortin 1 and 2 (Ucn-1 and Ucn-2) have established protective actions against myocardial ischemia-reperfusion (I/R) injuries. However, little is known about their role in posttranscriptional regulation in the process of cardioprotection. Herein, we investigated whether microRNAs play a role in urocortin-induced cardioprotection. Administration of Ucn-1 and Ucn-2 at the beginning of reperfusion significantly restored cardiac function, as evidenced ex vivo in Langendorff-perfused rat hearts and in vivo in rat subjected to I/R. Experiments using microarray and qRT-PCR determined that the addition of Ucn-1 at reperfusion modulated the expression of several miRNAs with unknown role in cardiac protection. Ucn-1 enhanced the expression of miR-125a-3p, miR-324-3p; meanwhile it decreased miR-139-3p. Similarly, intravenous infusion of Ucn-2 in rat model of I/R mimicked the effect of Ucn-1 on miR-324-3p and miR-139-3p. The effect of Ucn-1 involves the activation of corticotropin-releasing factor receptor-2, Epac2 and ERK1/2. Moreover, the overexpression of miR-125a-3p, miR-324-3p and miR-139-3p promoted dysregulation of genes expression involved in cell death and apoptosis (BRCA1, BIM, STAT2), in cAMP and Ca²⁺ signaling (PDE4a, CASQ1), in cell stress (NFAT5, XBP1, MAP3K12) and in metabolism (CPT2, FoxO1, MTRF1, TAZ). Altogether, these data unveil a novel role of urocortin in myocardial protection, involving posttranscriptional regulation with miRNAs.

CaMKIIδ meditates phenylephrine induced cardiomyocyte hypertrophy through store-operated Ca2+ entry

Evidence suggests that store-operated Ca2+ entry (SOCE) is involved in the hypertrophy of cardiomyocytes. The signaling mechanisms of SOCE contributing to cardiac hypertrophy following phenylephrine (PE) stimulation are not fully understood. Ca²⁺/calmodulin-dependent protein kinase II δ (CaMKIIδ) plays an important role in regulating intracellular Ca²⁺ hemostasis and function in the cardimyocytes. This study is aimed to determine the role of CaMKIIδ in regulating the PE-induced myocardial hypertrophy and the associated molecular signaling mechanisms. We used primary cultures of neonatal cardimyocytes isolated from the left ventricle of Sprague Dawley rats to investigate the effects of CaMKIIδ on myocardial hypertrophy and intracellular Ca²⁺ mobilization. We found that the expression of CaMKIIδ was enhanced in PE-induced hypertrophic cardiomyocytes. CaMKIIδ siRNA, CaMKII inhibitor KN93, and SOCE blocker BTP2 attenuated the increase in the expression of CaMKIIδ and normalized the hypertrophic markers, atrial natriuretic peptide and brain natriuretic peptide, and size of cardiomyocytes induced by PE stimulation. The protein level of stromal interaction molecule 1 and Orai1, the essential components of the SOCE, is also enhanced in hypertrophic cardiomyocytes, which were normalized by CaMKIIδ siRNA and KN93 treatment. Hypertrophic cardiomyocytes showed an increase in the peak of Ca²⁺ transient following store depletion, which was inhibited by SOCE blocker BTP2, CaMKIIδ siRNA, and KN93. The Ca²⁺ currents through Ca²⁺ release-activated Ca²⁺ channels were increased in PE-treated cardiomyocytes and were attenuated by CaMKIIδ siRNA and KN93. These data indicate that PE-induced myocardial hypertrophy requires a complex signaling pathway that involves activation of both CaMKIIδ and SOCE. In conclusion, these studies reveal that up-regulation of CaMKIIδ may contribute to the PE-induced myocardial hypertrophy through the activation of SOCE expressed in the cardiomyocytes.