Exercise training prevents obesity-associated disorders: Role of miRNA-208a and MED13

Cardiac-to-adipose axis in metabolic homeostasis and diseases: special instructions from the heart

Adipose tissue is essential for maintaining systemic metabolic homeostasis through traditional metabolic regulation, endocrine crosstalk, and extracellular vesicle production. Adipose dysfunction is a risk factor for cardiovascular diseases. The heart is a traditional pump organ. However, it has recently been recognized to coordinate interorgan cross-talk by providing peripheral signals known as cardiokines. These molecules include specific peptides, proteins, microRNAs and novel extracellular vesicle-carried cargoes. Current studies have shown that generalized cardiokine-mediated adipose regulation affects systemic metabolism. Cardiokines regulate lipolysis, adipogenesis, energy expenditure, thermogenesis during cold exposure and adipokine production. Moreover, cardiokines participate in pathological processes such as obesity, diabetes and ischemic heart injury. The underlying mechanisms of the cardiac-to-adipose axis mediated by cardiokines will be further discussed to provide potential therapeutic targets for metabolic diseases and support a new perspective on the need to correct adipose dysfunction after ischemic heart injury.

Swimming improves platelet dysfunction in mice fed with a high-fat diet

BACKGROUND

We investigated the effects and mechanism of swimming on platelet function in mice fed with a high-fat diet.

MATERIAL AND METHODS

Mice were randomly divided into the control group (NC), high-fat group (HF), and high-fat diet combined with swimming group (FE). The FE group swam for 60 min a day, 5 days a week, for 8 weeks.

RESULTS

Compared with the NC group, the HF group had significant weight gain, dyslipidemia, abbreviated bleeding time after tail breakage, increased clot retraction, increased platelet aggregation rate, increased spread of platelets on fibrinogen, and increased pAKT level in platelets. Compared with the HF group, the FE group had lower body weight, improved dyslipidemia, prolonged bleeding time, reduced clot retraction, reduced platelet aggregation rate, decreased spread of platelets on fibrinogen, and decreased pAKT level in platelets.

CONCLUSIONS

By inhibiting the level of pAKT in platelets, swimming improves platelet dysfunction in mice fed with a high-fat diet.

Regular Exercise in Drosophila Prevents Age-Related Cardiac Dysfunction Caused by High Fat and Heart-Specific Knockdown of skd

Skuld (skd) is a subunit of the Mediator complex subunit complex. In the heart, skd controls systemic obesity, is involved in systemic energy metabolism, and is closely linked to cardiac function and aging. However, it is unclear whether the effect of cardiac skd on cardiac energy metabolism affects cardiac function. We found that cardiac-specific knockdown of skd showed impaired cardiac function, metabolic impairment, and premature aging. Drosophila was subjected to an exercise and high-fat diet (HFD) intervention to explore the effects of exercise on cardiac skd expression and cardiac function in HFD Drosophila. We found that Hand-Gal4>skd RNAi (KC) Drosophila had impaired cardiac function, metabolic impairment, and premature aging. Regular exercise significantly improved cardiac function and metabolism and delayed aging in HFD KC Drosophila. Thus, our study found that the effect of skd on cardiac energy metabolism in the heart affected cardiac function. Exercise may counteract age-related cardiac dysfunction and metabolic disturbances caused by HFD and heart-specific knockdown of skd. Skd may be a potential therapeutic target for heart disease.

MicroRNAs in Obesity-Associated Disorders: The Role of Exercise Training

Obesity is a worldwide epidemic affecting over 13% of the adult population and is defined by an excess of body fat that predisposes comorbidities. It is considered a multifactorial disease in which environmental and genetic factors interact, and it is a risk marker for cardiovascular disease. Lifestyle modifications remain the mainstay of treatment for obesity based on adequate diet and physical exercise. In addition, obesity is related to cardiovascular and skeletal muscle disorders, such as cardiac hypertrophy, microvascular rarefaction, and skeletal muscle atrophy. The discovery of obesity-involved molecular pathways is an important step to improve both the prevention and management of this disease. MicroRNAs (miRNAs) are a class of gene regulators which bind most commonly, but not exclusively, to the 3'-untranslated regions of messenger RNAs of protein-coding genes and negatively regulate their expression. Considerable effort has been made to identify miRNAs and target genes that predispose to obesity. Besides their intracellular function, recent studies have demonstrated that miRNAs can be exported or released by cells and circulate within the blood in a remarkably stable form. The discovery of circulating miRNAs opens up intriguing possibilities for the use of circulating miRNA patterns as biomarkers for obesity and cardiovascular diseases. The aim of this review is to provide an overview of the recent discoveries of the role played by miRNAs in the obese phenotype and associated comorbidities. Furthermore, we will discuss the role of exercise training on regulating miRNAs, indicating the mechanisms related to these alterations.

lncRNA MIR4435‑2HG promotes the progression of liver cancer by upregulating B3GNT5 expression

Several studies have indicated that dysregulation of long non-coding RNAs (lncRNAs) participates in the initiation and progression of cancer. The lncRNA MIR4435-2HG was previously reported to act as an oncogene in human cancer, including liver cancer. However, its role in the pathogenesis in liver cancer is largely unclear. The present study aimed to reveal the molecular mechanism by which MIR4435-2HG regulates liver cancer. The expression levels of MIR4435-2HG in liver cancer and adjacent normal tissues were analyzed using The Cancer Genome Atlas database. MIR4435-2HG expression was validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in cancer cells in vitro. The target genes of MIR4435-2HG were predicted using bioinformatics analysis. Interactions between miR-136-5p, MIR4435-2HG and B3GNT5 were detected using luciferase reporter assays, and their effects on cell viability, migration and invasion were assessed using Cell Counting Kit-8, wound healing and Transwell assays. The effects of miR-136-5p and MIR4435-2HG on B3GNT5 expression were confirmed by western blot analysis. The results revealed that MIR4435-2HG expression was upregulated in primary liver cancer and liver cancer cell lines, and was positively associated with advanced tumor stage, metastasis and poor prognosis in patients with liver cancer. Knockdown of MIR4435-2HG significantly inhibited the proliferation, migration and invasion of liver cancer cells. Furthermore, miR-136-5p was determined to be a direct target of MIR4435-2HG and suppressed MIR4435-2HG expression by binding with the seed region of the 3′-UTR of MIR4435-2HG in liver cancer cells. Functional studies showed that the inhibitory effects of MIR4435-2HG knockdown on cell proliferation, migration and invasion were significantly rescued by inhibiting miR-136-5p. Furthermore, the target gene, B3GNT5, of miR-136-5p was confirmed by bioinformatics analysis and RT-qPCR. In addition, B3GNT5 expression was regulated by the MIR4435-2HG/miR-136-5p axis. In conclusion, the present study indicated that MIR4435-2HG facilitated the progression of liver cancer via the MIR4435-2HG/miR-136-5p/B3GNT5 axis, which demonstrated that MIR4435-2HG may be a potential biomarker for the prognosis and treatment of liver cancer.

The importance of RNA modifications: From cells to muscle physiology

Naturally occurring post-transcriptional chemical modifications serve critical roles in impacting RNA structure and function. More directly, modifications may affect RNA stability, intracellular transport, translational efficiency, and fidelity. The combination of effects caused by modifications are ultimately linked to gene expression regulation at a genome-wide scale. The latter is especially true in systems that undergo rapid metabolic and or translational remodeling in response to external stimuli, such as the presence of stressors, but beyond that, modifications may also affect cell homeostasis. Although examples of the importance of RNA modifications in translation are accumulating rapidly, still what these contribute to the function of complex physiological systems such as muscle is only recently emerging. In the present review, we will introduce key information on various modifications and highlight connections between those and cellular malfunctions. In passing, we will describe well-documented roles for modifications in the nervous system and use this information as a stepping stone to emphasize a glaring paucity of knowledge on the role of RNA modifications in heart and skeletal muscle, with particular emphasis on mitochondrial function in those systems. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > RNA Editing and Modification.

Emerging roles of microRNA-208a in cardiology and reverse cardio-oncology

Cardiovascular diseases (CVDs) and cancer, which are the leading causes of mortality globally, have been viewed as two distinct diseases. However, the fact that cancer and CVDs may coincide has been noted by cardiologists when taking care of patients with CVDs caused by cancer chemotherapy; this entity is designated cardio-oncology. More recently, patients with CVDs have also been found to have increased risk of cancers, termed reverse cardio-oncology. Although reverse cardio-oncology has been highlighted as an important disease state in recent studies, how the diseased heart affects cancer and the potential mediators of the crosstalk between CVDs and cancer are largely unknown. Here, we focus on the roles of cardiac-specific microRNA-208a (miR-208a) in cardiac and cancer biology and explore its essential roles in reverse cardio-oncology. Accumulating evidence has shown that within the heart, increased miR-208a promotes myocardial injury, arrhythmia, cardiac remodeling, and dysfunction and that secreted miR-208a in the circulation may have novel roles in promoting tumor proliferation and invasion. This review, therefore, provides insights into the novel roles of miR-208a in reverse cardio-oncology and strategies to prevent secondary carcinogenesis in patients with early- or late-stage heart failure.

Network analysis of the left anterior descending coronary arteries in swim-trained rats by an in situ video microscopic technique

BACKGROUND

We aimed to identify sex differences in the network properties and to recognize the geometric alteration effects of long-term swim training in a rat model of exercise-induced left ventricular (LV) hypertrophy.

METHODS

Thirty-eight Wistar rats were divided into four groups: male sedentary, female sedentary, male exercised and female exercised. After training sessions, LV morphology and function were checked by echocardiography. The geometry of the left coronary artery system was analysed on pressure-perfused, microsurgically prepared resistance artery networks using in situ video microscopy. All segments over > 80 μm in diameter were studied using divided 50-μm-long cylindrical ring units of the networks. Oxidative-nitrative (O-N) stress markers, adenosine A2A and estrogen receptor (ER) were investigated by immunohistochemistry.

RESULTS

The LV mass index, ejection fraction and fractional shortening significantly increased in exercised animals. We found substantial sex differences in the coronary network in the control groups and in the swim-trained animals. Ring frequency spectra were significantly different between male and female animals in both the sedentary and trained groups. The thickness of the wall was higher in males as a result of training. There were elevations in the populations of 200- and 400-μm vessel units in males; the thinner ones developed farther and the thicker ones closer to the orifice. In females, a new population of 200- to 250-μm vessels appeared unusually close to the orifice.

CONCLUSIONS

Physical activity and LV hypertrophy were accompanied by a remodelling of coronary resistance artery network geometry that was different in both sexes.

Potential roles of mediator Complex Subunit 13 in Cardiac Diseases

Mediator complex subunit 13 (MED13, previously known as THRAP1 and TRAP240) is a subunit of the cyclin-dependent kinase 8 (CDK8) kinase module in the eukaryotic mediator complex. MED13 has been known to play critical roles in cell cycle, development, and growth. The purpose of this review is to comprehensively discuss its newly identified potential roles in myocardial energy metabolism and non-metabolic cardiovascular diseases. Evidence indicates that cardiac MED13 mainly participates in the regulation of nuclear receptor signaling, which drives the transcription of genes involved in modulating cardiac and systemic energy homeostasis. MED13 is also associated with several pathological conditions, such as metabolic syndrome and thyroid disease-associated heart failure. Therefore, MED13 constitutes a potential therapeutic target for the regulation of metabolic disorders and other cardiovascular diseases.

MicroRNA-212 targets SIRT2 to influence lipogenesis in bovine mammary epithelial cell line

In this research paper we filter and verify miRNAs which may target silent information regulator homolog 2 (SIRT2) gene and then describe the mechanism whereby miRNA-212 might regulate lipogenic genes in mammary epithelial cell lines via targeting SIRT2. Bioinformatics analysis revealed that the bovine SIRT2 gene is regulated by three miRNAs: miR-212, miR-375 and miR-655. The three miRNAs were verified and screened by qRT-PCR, western blot, and luciferase multiplex verification techniques and only miR-212 was shown to have a targeting relationship with SIRT2. The results of co-transfecting miR-212 and silencing RNA (siRNA) showed that by targeting SIRT2, miR-212 can regulate the expression of fatty acid synthetase (FASN) and sterol regulatory element binding factor 1 (SREBP1) but not peroxisome proliferator-activated receptor gamma (PPARγ). Measurement of triglyceride (TAG) content showed that miR-212 increased the fat content of mammary epithelial cell lines. The study indicates that miR-212 could target and inhibit the expression of the SIRT2 gene to promote lipogenesis in mammary epithelial cell lines.

MicroRNA-499-5p regulates skeletal myofiber specification via NFATc1/MEF2C pathway and Thrap1/MEF2C axis

AIMS

This study aimed to investigate the role of microRNA-499-5p (miR-499-5p) in the regulation of skeletal myofiber specification and its underlying mechanisms.

MAIN METHODS

Mouse C2C12 cells were used in this study. Cyclosporin A and siRNA targeting Thrap1 (si-Thrap1) were used to inhibit NFATc1/MEF2C pathway and knockdown Thrap1, respectively. The expressions of miR-499-5p and genes were evaluated by real-time quantitative PCR and western blot analysis.

KEY FINDINGS

Overexpression of miR-499-5p promoted oxidative fiber gene expression and repressed glycolytic fiber gene expression, affecting several factors associated with fiber specification including NFATc1/MEF2C pathway, PGC-1α, FoxO1 and Wnt5a. Inhibition of NFATc1/MEF2C pathway partly reduced the effect of miR-499-5p overexpression on muscle fiber gene expression. MiR-499-5p targeted Thrap1 in proliferating and differentiating C2C12 cells. Knockdown of Thrap1 showed a parallel function with miR-499-5p overexpression on muscle fiber gene expression and NFATc1/MEF2C pathway, accompanied by an increase of miR-499-5p level. The effects of miR-499-5p inhibitor on muscle fiber type specific gene expression and NFATc1/MEF2C pathway were effectively reversed by Thrap1 knockdown.

SIGNIFICANCE

MiR-499-5p regulated skeletal myofiber specification and affected several factors associated with fiber specification. MiR-499-5p regulated muscle gene expression partly through NFATc1/MEF2C pathway. We also showed a clue that miR-499-5p regulates skeletal muscle fiber specification in C2C12 cells through targeting Thrap1, thereby, promoting NFATc1/MEF2C pathway and then triggering a series of oxidative muscle fiber gene expression.