MicroRNA-206: the skeletal muscle-specific myomiR

Muscle-Derived Bioactive Factors: MyoEVs and Myokines

Overview of the functions and applications of myokines and MyoEVs.

A primer on global molecular responses to exercise in skeletal muscle: Omics in focus

Advances in skeletal muscle omics has expanded our understanding of exercise-induced adaptations at the molecular level. Over the past 2 decades, transcriptome studies in muscle have detailed acute and chronic responses to resistance, endurance, and concurrent exercise, focusing on variables such as training status, nutrition, age, sex, and metabolic health profile. Multi-omics approaches, such as the integration of transcriptomic and epigenetic data, along with emerging ribosomal RNA sequencing advancements, have further provided insights into how skeletal muscle adapts to exercise across the lifespan. Downstream of the transcriptome, proteomic and phosphoproteomic studies have identified novel regulators of exercise adaptations, while single-cell/nucleus and spatial sequencing technologies promise to evolve our understanding of cellular specialization and communication in and around skeletal muscle cells. This narrative review highlights (a) the historical foundations of exercise omics in skeletal muscle, (b) current research at 3 layers of the omics cascade (DNA, RNA, and protein), and (c) applications of single-cell omics and spatial sequencing technologies to study skeletal muscle adaptation to exercise. Further elaboration of muscle's global molecular footprint using multi-omics methods will help researchers and practitioners develop more effective and targeted approaches to improve skeletal muscle health as well as athletic performance.

miRNA-1 regulation is necessary for mechanical overload-induced muscle hypertrophy in male mice

MicroRNAs (miRNAs) are small, noncoding RNAs that play a critical role in regulating gene expression post-transcriptionally. They are involved in various developmental and physiological processes, and their dysregulation is linked to various diseases. Skeletal muscle-specific miRNAs, including miR-1, play a crucial role in the development and maintenance of skeletal muscle. It has been demonstrated that the expression of miR-1 decreases by approximately 50% in response to hypertrophic stimuli, suggesting its potential involvement in muscle hypertrophy. In our study, we hypothesize that reduction of miR-1 levels is necessary for skeletal muscle growth due to its interaction to essential pro-growth genes. Promoting a smaller reduction of miR-1 levels, we observed a blunted hypertrophic response in mice undergoing a murine model of muscle hypertrophy. In addition, our results suggest that miR-1 inhibits the expression of Itm2a, a membrane-related protein, as potential miR-1-related candidate for skeletal muscle hypertrophy. While the exact mechanism in muscle hypertrophy has not been identified, our results suggest that miR-1-regulated membrane proteins are important for skeletal muscle hypertrophy.

Brain-Periphery Axes: The Potential Role of Extracellular Vesicles-Delivered miRNAs

Bidirectional communication between the central nervous system (CNS) and peripheral organs and tissue has been widely documented in physiological and pathological conditions. This communication relies on the bilateral transmission of signaling molecules and substances that circulate throughout the body and reach their target site(s) via the blood and other biological fluids (e.g., the cerebrospinal fluid, the lymph). One of the mechanisms by which these molecular messengers are exchanged is through the secretion of extracellular vesicles (EVs). EVs are known to mediate cell-to-cell communication by delivering biological molecules, including nucleic acids, proteins, lipids, and various other bioactive regulators. Moreover, EVs can cross the blood-brain barrier (BBB), enabling direct communication between the periphery and the brain. In particular, the delivery of microRNAs (miRNAs) can modulate the expression profiles of recipient cells, thereby influencing their functions. This review synthesizes current findings about the brain-periphery cross-talk mediated by EVs-delivered miRNAs. Although this mechanism has been definitively shown in a few cases, much evidence indirectly indicates that it could mediate brain-peripherical organs/tissue communication, especially in pathological conditions. Therefore, understanding this process could provide valuable insights for the treatment and management of neurological and systemic diseases.

Regulation of miR-206 in denervated and dystrophic muscles, and its effect on acetylcholine receptor clustering

The muscle-specific microRNA miR-206 has recently emerged as a potential regulator of genes involved in the formation and regeneration of the neuromuscular junction (NMJ). This study investigated miR-206-3p (miR-206) expression in synaptic and non-synaptic regions of denervated mice and α-dystrobrevin (Dtna)-knockout mice, as well as its impact on the formation and/or maintenance of agrin-induced acetylcholine receptor (AChR) clusters. In denervated, Dtna-deficient and crushed muscles, miR-206 expression significantly increased compared to what was seen for innervated muscles. Although miR-206 expression was slightly elevated in the synaptic regions of innervated muscles, it was dramatically increased in non-synaptic areas of denervated muscles. miR-206 targets transcripts of essential NMJ proteins, such as Dtna, α-syntrophin (Snta1) and rapsyn, but not the AChRα subunit (encoded by Chrna1) or Lrp4 in innervated muscles. However, in denervated muscles, AChRα transcripts, which increased significantly, become a target of miR-206. Co-expression of miR-206 with rapsyn, Dtna and Snta1 in C2C12 myoblasts significantly reduced their protein levels, and overexpression of miR-206 in myotubes disrupted agrin-induced AChR clustering. These results indicate that miR-206 fine-tunes NMJ signaling proteins by regulating transcripts of various proteins with different localizations under normal and pathological conditions.

Plasma-derived extracellular vesicles miR-335-5p as potential diagnostic biomarkers for fusion-positive rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma, with embryonal (ERMS) and alveolar (ARMS) representing the two most common histological subtypes. ARMS shows poor prognosis, being often metastatic at diagnosis. Thus, the discovery of novel biomarkers predictive of tumor aggressiveness represents one of the most important challenges to overcome and may help the development of tailored therapies. In the last years, miRNAs carried in extracellular vesicles (EVs), small vesicles of endocytic origin, have emerged as ideal candidate biomarkers due to their stability in plasma and their tissue specificity.

METHODS

EVs miRNAs were isolated from plasma of 21 patients affected by RMS and 13 healthy childrens (HC). We performed a miRNA profile using the Serum/Plasma Focus microRNA PCR panels (Qiagen), and RT-qPCR for validation analysis. Statistically significant (p < 0.05) miRNAs were obtained by ANOVA test.

RESULTS

We identified nine EVs miRNAs (miR-483-5p, miR-132-3p, miR-766-3p, miR-454-3p miR-197-3p, miR-335-3p, miR-17-5p, miR-486-5p and miR-484) highly upregulated in RMS patients compared to HCs. Interestingly, 4 miRNAs (miR-335-5p, miR-17-5p, miR-486-5p and miR-484) were significantly upregulated in ARMS samples compared to ERMS. In the validation analysis performed in a larger group of patients only three miRNAs (miR-483-5p, miR-335-5p and miR-484) were differentially significantly expressed in RMS patients compared to HC. Among these, mir-335-5p was significant also when compared ARMS to ERMS patients. MiR-335-5p was upregulated in RMS tumor tissues respect to normal tissues (p = 0.00202) and upregulated significantly between ARMS and ERMS (p = 0.04). Furthermore, the miRNA expression correlated with the Intergroup Rhabdomyosarcoma Study (IRS) grouping system, (p = 0.0234), and survival (OS, p = 0.044; PFS, p = 0.025). By performing in situ hybridization, we observed that miR-335-5p signal was exclusively in the cytoplasm of cancer cells.

CONCLUSION

We identified miR-335-5p as significantly upregulated in plasma derived EVs and tumor tissue of patients affected by ARMS. Its expression correlates to stage and survival in patients. Future studies are needed to validate miR-335-5p as prognostic biomarker and to deeply elucidate its biological role.

Identification of key lncRNAs and mRNAs in muscle development pathways of Tan sheep

The study aimed to identify the long noncoding RNA (lncRNA) responsible for regulating muscle development in Tan sheep. RNA-seq analysis was conducted on longissimus dorsi samples from 1-day-old and 60-day-old Tan sheep to investigate the molecular processes involved in muscle development. A total of 5517 lncRNAs and 2885 mRNAs were found to be differentially expressed in the 60-day-old Tan sheep. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that these differentially expressed lncRNAs and mRNAs were linked to pathways crucial for muscle development, such as MAPK, cAMP, and calcium-mediated signaling pathways. Key genes like CDKN1A, MAPK14, TGFB1, MEF2C, MYOD1, and CD53 were identified as significant players in muscle development. The study validated the RNA-seq results through RT-qPCR, confirming the consistency of expression levels of differentially expressed lncRNAs and mRNAs. These findings indicate that lncRNA-mRNA networks produce a remarked effect on modulating muscle development in Tan sheep, such as lncRNAs (MSTRG.12808.1/MSTRG.22662.3/MSTRG.18310.1) and mRNAs (MSTRG.10027/MSTRG.10029/MSTRG.10258/MSTRG.11011/MSTRG.10354), laying the groundwork for future research in this area.

Analysis of plasma-derived small extracellular vesicle characteristics and microRNA cargo following exercise-induced skeletal muscle damage in men

Extracellular vesicle (EV) cargo is known to change in response to stimuli such as muscle damage. This study aimed to assess particle size, concentration and microRNA (miR) content within small EV-enriched separations prepared from human blood taken before and after unaccustomed eccentric-biased exercise-induced muscle damage. Nine male volunteers underwent plyometric jumping and downhill running, with blood samples taken at baseline, 2, and 24 h post-exercise. EVs were separated using size exclusion chromatography (SEC) and their characteristics evaluated by nanoparticle tracking. No changes in EV size or concentration were seen following the muscle-damaging exercise. Small RNA sequencing identified 240 miRs to be consistently present within the EVs. RT-qPCR analysis was performed: specifically, for known muscle-enriched/important miRs, including miR-1, -206, -133a, -133b, -31, -208b, -451a, -486 and - 499 and the immune-important miR-21, -146a and - 155. Notably, none of the immune-important miRs within the EVs tested changed in response to the muscle damage. Of the muscle-associated miRs tested, only the levels of miR-31-5p were seen to change with decreased levels at 24 h compared to baseline and 2 h, indicating involvement in the damage response. These findings shed light on the dynamic role of EV miRs in response to exercise-induced muscle damage.

Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle

Myokines and exosomes, originating from skeletal muscle, are shown to play a significant role in maintaining brain homeostasis. While exercise has been reported to promote muscle secretion, little is known about the effects of neuronal innervation and activity on the yield and molecular composition of biologically active molecules from muscle. As neuromuscular diseases and disabilities associated with denervation impact muscle metabolism, we hypothesize that neuronal innervation and firing may play a pivotal role in regulating secretion activities of skeletal muscles. We examined this hypothesis using an engineered neuromuscular tissue model consisting of skeletal muscles innervated by motor neurons. The innervated muscles displayed elevated expression of mRNAs encoding neurotrophic myokines, such as interleukin-6, brain-derived neurotrophic factor, and FDNC5, as well as the mRNA of peroxisome-proliferator-activated receptor γ coactivator 1α, a key regulator of muscle metabolism. Upon glutamate stimulation, the innervated muscles secreted higher levels of irisin and exosomes containing more diverse neurotrophic microRNAs than neuron-free muscles. Consequently, biological factors secreted by innervated muscles enhanced branching, axonal transport, and, ultimately, spontaneous network activities of primary hippocampal neurons in vitro. Overall, these results reveal the importance of neuronal innervation in modulating muscle-derived factors that promote neuronal function and suggest that the engineered neuromuscular tissue model holds significant promise as a platform for producing neurotrophic molecules.

Identification of Plasmatic MicroRNA-206 as New Predictor of Early Recurrence of Atrial Fibrillation After Catheter Ablation Using Next-generation Sequencing

BACKGROUND

Catheter ablation (CA) of atrial fibrillation (AF) is indicated in patients with recurrent and symptomatic AF episodes. Despite the strict inclusion/exclusion criteria, AF recurrence after CA remains high. Identification of a novel biomarker that would predict AF recurrence would help to stratify the patients. The aim of the study was to seek novel biomarkers among the plasmatic microRNAs (miRNAs, miRs).

METHODS

A prospective monocentric study was conducted. A total of 49 consecutive AF patients indicated for CA were included. Blood sampling was performed prior to CA. RNA was isolated from plasma using commercial kits. In the exploration phase, small RNA sequencing was performed in ten AF patients (five with and five without AF recurrence) using Illumina instrument. In the validation phase, levels of selected miRNAs were determined using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in all participants.

RESULTS

Altogether, 22 miRNAs were identified as altered between the groups by next-generation sequencing (using the DESeq2 algorithm). Using qRT-PCR, levels of the five most altered miRNAs (miR-190b/206/326/505-5p/1296-5p) were verified in the whole cohort. Plasma levels of hsa-miR-206 were significantly higher in patients with early (within 6 months) AF recurrence and showed an increase of risk recurrence,2.65 times by every increase in its level by 1 unit in the binary logistic regression.

CONCLUSION

We have identified a set of 22 plasmatic miRNAs that differ between the patients with and without AF recurrence after CA and confirmed hsa-miR-206 as a novel miRNA associated with early AF recurrence. Results shall be verified in a larger independent cohort.

Comprehensive analysis of microRNA expression in lumbar facet joint capsules and synovium of patients with osteoarthritis: Comparison between early-stage and late-stage osteoarthritis samples from a single individual

BACKGROUND

MicroRNA is attracting attention as a therapeutic target for osteoarthritis. We focused on joint capsules and synovium in lumbar facet joint osteoarthritis. The purpose of this study was to identify microRNAs that are upregulated in lumbar facet joint capsules and synovium with osteoarthritis.

METHODS

We included patients who underwent spinal fusion for degenerative lumbar spine diseases. We selected patients who had both early-stage and late-stage facet joint osteoarthritis in a single individual. We extracted joint capsule and synovium samples from these patients and isolated microRNAs. During the screening phase, we compared early-stage and late-stage osteoarthritis samples from the same individual. We identified microRNAs with >2-fold change in expression in 75% or more of patients with late-stage osteoarthritis using next generation sequencing. During the technical validation phase, the same samples were used for real-time polymerase chain reaction. We identified microRNAs with >2-fold change in expression in 62.5% or more of patients with late-stage osteoarthritis.

RESULTS

Of 40 patients who underwent spinal fusion, we selected eight patients with both early-stage and late-stage facet joint osteoarthritis. During the screening phase, we identified eight upregulated microRNAs out of 2274 microRNAs in late-stage OA. In late-stage OA, two microRNAs (miR-133a-5p and miR-144-3p) were upregulated in seven patients and six microRNAs (miR-133a-3p, miR-133b, miR-206, miR-20a-5p, miR-301a-3p, and miR-32-5p) were upregulated in six patients. During the technical validation phase, we found significant upregulation of miR-144-3p expression in late-stage osteoarthritis compared with early-stage osteoarthritis. Expression of the other microRNAs was not significantly different according to the paired-t test. However, miR-133a-3p, miR-133b, and miR-206 were upregulated >2-fold in 62.5% or more of patients with late-stage osteoarthritis.

CONCLUSIONS

Some of the microRNAs identified in this study might be involved in joint capsule degeneration or synovitis.

Increased Expression of MiRNA-1 Contributes to Hypobaric Hypoxia-Induced Skeletal Muscle Loss

The present study aims to analyze the role of microRNA-1 in the regulation of skeletal muscle loss under hypobaric hypoxia (HH). Male Sprague Dawley rats (n = 10) weighing 230-250 g are divided into two groups, control and HH exposure for 7 days at 25 000 ft. After the hypoxia exposure, the animals are sacrificed and hindlimb skeletal muscles are excised for further analysis. Studies found the potential role of miR-1 (myomiR) as a biomarker under different atrophic conditions. Prolonged exposure to HH leads to enhanced expression of miR-1 in skeletal muscle as compared to unexposed controls. The Bioinformatics approach is used to identify the validated targets and the biological processes of miR-1. The target prediction tools identify PAX3 and HSP70 as major targets for miR-1. Exposure to HH significantly reduces PAX3 and HSP70 expression during 7 days of HH exposure, which further enhances the activity of FOXO3, MSTN, and ATROGIN known for the progression of skeletal muscle atrophy in relation to control rats. This study indicates the increased expressions of miR-1 and reduced expression of PAX3 and HSP70 lead to impaired myogenesis in skeletal muscle under HH. Further, enhanced expression of muscle degradation genes such as FOXO3, MSTN, and ATROGIN under HH exposure causes skeletal muscle protein loss.

Muscle stem cell dysfunction in rhabdomyosarcoma and muscular dystrophy

Muscle stem cells (MuSCs) are crucial to the repair and homeostasis of mature skeletal muscle. MuSC dysfunction and dysregulation of the myogenic program can contribute to the development of pathology ranging from cancers like rhabdomyosarcoma (RMS) or muscle degenerative diseases such as Duchenne muscular dystrophy (DMD). Both diseases exhibit dysregulation at nearly all steps of myogenesis. For instance, MuSC self-renewal processes are altered. In RMS, this leads to the creation of tumor propagating cells. In DMD, impaired asymmetric stem cell division creates a bias towards producing self-renewing stem cells instead of committing to differentiation. Hyperproliferation of these cells contribute to tumorigenesis in RMS and symmetric expansion of the self-renewing MuSC population in DMD. Both diseases also exhibit a repression of factors involved in terminal differentiation, halting RMS cells in the proliferative stage and thus driving tumor growth. Conversely, the MuSCs in DMD exhibit impaired differentiation and fuse prematurely, affecting myonuclei maturation and the integrity of the dystrophic muscle fiber. Finally, both disease states cause alterations to the MuSC niche. Various elements of the niche such as inflammatory and migratory signaling that impact MuSC behavior are dysregulated. Here we show how these seemingly distantly related diseases indeed have similarities in MuSC dysfunction, underlying the importance of considering MuSCs when studying the pathophysiology of muscle diseases.

Bovine Skeletal Muscle Satellite Cells: Isolation, Growth, and Differentiation

Skeletal muscle in cattle occupies a large part of the animal's body mass and develops into an important source of nutrients for human nutrition. Recently, the attention on bovine myogenic cells is increased to develop strategies of cultured in vitro meat as an alternative food source, more sustainable, ethical, and healthy than traditional meat production. At present, investigating the proliferation and differentiation of bovine skeletal muscle myogenic cells in vitro maintains its importance in the study of the mechanisms underlying the physiological and pathological events affecting the skeletal muscle, but it is of particular interest in animal husbandry and the food industry fields.In cell-based biological research, cell lines are one of the favored experimental tools because a population of cells could proliferate indefinitely in vitro under different stimuli, but they are limited to addressing the relevant biological properties of a cell population. On the other hand, primary cells from normal animal tissues undergo a limited number of divisions in vitro before they enter senescence but preserve their original characteristics and functions, and researchers can acquire the opportunity to study the individual donors and not just cells.In this chapter, we provide a basic protocol to isolate satellite cells from the skeletal muscle of cattle to obtain a good number of myogenic cells that can grow in in vitro conditions and undergo multiple rounds of cell division (myoblasts) before entering differentiation (myotubes). Furthermore, the robust expansion of these cells leads to the possibility to investigate physiological events or disorders related to the skeletal muscle tissue.

A Comprehensive Review on the Importance of MiRNA-206 in the Animal Model and Human Diseases

MicroRNA-206 (miR-206) is a microRNA that is involved in many human diseases, such as myasthenia gravis, osteoarthritis, depression, cancers, etc. Both inhibition effects and progression roles of miR-206 have been reported for the past few years. High expression of miR-206 was observed in patients with osteoarthritis, gastric cancer and epithelial ovarian cancer compared to normal people. The study also showed that miR-206 promotes cancer progression in breast cancer patients and avascular necrosis of the femoral head. Meanwhile, several studies have shown that expression levels of miR-206 were down-regulated in laryngeal carcinoma cell multiplication, as well as in hepatocellular carcinoma, non-small lung cancer and infantile hemangioma. Moreover, miR-206 was up-regulated in the mild stage of amyotrophic lateral sclerosis patients and then down-regulated in the moderate and severe stages, indicating that miR-206 has the double effects of starting and aggravating the disease. In neuropsychiatric disorders, such as depression, miR-206 also plays an important role in the progression of the disease; the level of miR-206 is most highly expressed in the brains of patients with depression. In the current review, we summarize the role of miR-206 in various diseases, and miR-206 may be developed as a new biomarker for diagnosing diseases in the near future.

Integrated small RNA, mRNA and protein omics reveal a miRNA network orchestrating metabolic maturation of the developing human heart

BACKGROUND

As the fetal heart develops, cardiomyocyte proliferation potential decreases while fatty acid oxidative capacity increases in a highly regulated transition known as cardiac maturation. Small noncoding RNAs, such as microRNAs (miRNAs), contribute to the establishment and control of tissue-specific transcriptional programs. However, small RNA expression dynamics and genome-wide miRNA regulatory networks controlling maturation of the human fetal heart remain poorly understood.

RESULTS

Transcriptome profiling of small RNAs revealed the temporal expression patterns of miRNA, piRNA, circRNA, snoRNA, snRNA and tRNA in the developing human heart between 8 and 19 weeks of gestation. Our analysis demonstrated that miRNAs were the most dynamically expressed small RNA species throughout mid-gestation. Cross-referencing differentially expressed miRNAs and mRNAs predicted 6200 mRNA targets, 2134 of which were upregulated and 4066 downregulated as gestation progressed. Moreover, we found that downregulated targets of upregulated miRNAs, including hsa-let-7b, miR-1-3p, miR-133a-3p, miR-143-3p, miR-499a-5p, and miR-30a-5p predominantly control cell cycle progression. In contrast, upregulated targets of downregulated miRNAs, including hsa-miR-1276, miR-183-5p, miR-1229-3p, miR-615-3p, miR-421, miR-200b-3p and miR-18a-3p, are linked to energy sensing and oxidative metabolism. Furthermore, integrating miRNA and mRNA profiles with proteomes and reporter metabolites revealed that proteins encoded in mRNA targets and their associated metabolites mediate fatty acid oxidation and are enriched as the heart develops.

CONCLUSIONS

This study presents the first comprehensive analysis of the small RNAome of the maturing human fetal heart. Our findings suggest that coordinated activation and repression of miRNA expression throughout mid-gestation is essential to establish a dynamic miRNA-mRNA-protein network that decreases cardiomyocyte proliferation potential while increasing the oxidative capacity of the maturing human fetal heart. Our results provide novel insights into the molecular control of metabolic maturation of the human fetal heart.

The roles of miRNAs in adult skeletal muscle satellite cells

Satellite cells are bona fide muscle stem cells that are indispensable for successful post-natal muscle growth and regeneration after severe injury. These cells also participate in adult muscle adaptation in several capacities. MicroRNAs (miRNAs) are post-transcriptional regulators of mRNA that are implicated in several aspects of stem cell function. There is evidence to suggest that miRNAs affect satellite cell behavior in vivo during development and myogenic progenitor behavior in vitro, but the role of miRNAs in adult skeletal muscle satellite cells is less studied. In this review, we provide evidence for how miRNAs control satellite cell function with emphasis on satellite cells of adult skeletal muscle in vivo. We first outline how miRNAs are indispensable for satellite cell viability and control the phases of myogenesis. Next, we discuss the interplay between miRNAs and myogenic cell redox status, senescence, and communication to other muscle-resident cells during muscle adaptation. Results from recent satellite cell miRNA profiling studies are also summarized. In vitro experiments in primary myogenic cells and cell lines have been invaluable for exploring the influence of miRNAs, but we identify a need for novel genetic tools to further interrogate how miRNAs control satellite cell behavior in adult skeletal muscle in vivo.

High expression of miR-30c-5p in satellite cells of high-fat diet-induced obese rabbits inhibited satellite cell proliferation and promoted differentiation

It was revealed in our previous study that the expression of miR-30c-5p in the skeletal muscle of rabbits fed high-fat diet was highly expressed. In the present study, we further investigated the function of miR-30c-5p in proliferation and differentiation of skeletal muscle satellite cell (SMSC). The results obtained in the present study showed that the skeletal muscle fibers of the rabbits fed the standard normal diet (SND) were orderly, regular, and uniform after HE staining, however, the muscle fibers of the rabbits fed the high-fat diet (HFD) were generally atrophied, some were arranged disorderly, the intercellular space was enlarged, the nucleus was increased, and the morphology and position were abnormal. Compared with the SND group, it was observed that the weekly weight gain and fat percentage were relatively higher, and also the levels of the serum biochemical indexes such as glucose, cholesterol, and triglyceride increased significantly in the rabbits fed with HFD. In addition, the results after the transfection of miR-30c-5p mimic, mimic NC (negative control), miR-30c-5p inhibitor, and inhibitor NC into the SMSCs showed that the cell counting kit-8 (CCK-8) proliferation experiment suggested that the number of cells in the over expression group was significantly lower than that in the mimic NC group at 48, 72, 96 h of cell proliferation. At 48, 72, 120 h, the number of cells in the inhibitor group was significantly higher than that in the mimic NC group. The number of EdU positive cells decreased significantly in the over expression group compared with the mimic NC group, however, it increased significantly in the inhibitor group compared with the inhibitor NC group. Moreover, compared with the mimic NC group, the myotube area increased significantly in the miR-30c-5p mimic group, whereas it decreased significantly in the miR-30c-5p inhibitor group as compared with the inhibitor NC group. In addition, we found that trinucleotide repeat containing adaptor 6A (TNRC6A) was successfully validated as a target gene for miR-30c-5p. The expression of TNRC6A in the miR-30c-5p mimic group was significantly lower than that in the mimic NC group. It was further observed that the expression of TNRC6A increased significantly in the miR-30c-5p inhibitor group as compared to that in the inhibitor NC group. Taken together, the results obtained in this study showed that miR-30c-5p promotes the differentiation as well as inhibits the proliferation of rabbit skeletal muscle satellite cells, and TNRC6A is a target gene of miR-30c-5p.

Idiopathic inflammatory myopathy and non-coding RNA

Idiopathic inflammatory myopathies (IIMs) are common autoimmune diseases that affect skeletal muscle quality and function. The lack of an early diagnosis and treatment can lead to irreversible muscle damage. Non-coding RNAs (ncRNAs) play an important role in inflammatory transfer, muscle regeneration, differentiation, and regulation of specific antibody levels and pain in IIMs. ncRNAs can be detected in blood and hair; therefore, ncRNAs detection has great potential for diagnosing, preventing, and treating IIMs in conjunction with other methods. However, the specific roles and mechanisms underlying the regulation of IIMs and their subtypes remain unclear. Here, we review the mechanisms by which micro RNAs and long non-coding RNA-messenger RNA networks regulate IIMs to provide a basis for ncRNAs use as diagnostic tools and therapeutic targets for IIMs.

Recent Advances in Extracellular Vesicles in Amyotrophic Lateral Sclerosis and Emergent Perspectives

Amyotrophic lateral sclerosis (ALS) is a severe and incurable neurodegenerative disease characterized by the progressive death of motor neurons, leading to paralysis and death. It is a rare disease characterized by high patient-to-patient heterogeneity, which makes its study arduous and complex. Extracellular vesicles (EVs) have emerged as important players in the development of ALS. Thus, ALS phenotype-expressing cells can spread their abnormal bioactive cargo through the secretion of EVs, even in distant tissues. Importantly, owing to their nature and composition, EVs' formation and cargo can be exploited for better comprehension of this elusive disease and identification of novel biomarkers, as well as for potential therapeutic applications, such as those based on stem cell-derived exosomes. This review highlights recent advances in the identification of the role of EVs in ALS etiopathology and how EVs can be promising new therapeutic strategies.

Comparative microRNA profiling of Trypanosoma cruzi infected human cells

Introduction

Trypanosoma cruzi, the causative agent of Chagas disease, can infect almost any nucleated cell in the mammalian host. Although previous studies have described the transcriptomic changes that occur in host cells during parasite infection, the understanding of the role of post-transcriptional regulation in this process is limited. MicroRNAs, a class of short non-coding RNAs, are key players in regulating gene expression at the post-transcriptional level, and their involvement in the host-T. cruzi interplay is a growing area of research. However, to our knowledge, there are no comparative studies on the microRNA changes that occur in different cell types in response to T. cruzi infection.

Methods and results

Here we investigated microRNA changes in epithelial cells, cardiomyocytes and macrophages infected with T. cruzi for 24 hours, using small RNA sequencing followed by careful bioinformatics analysis. We show that, although microRNAs are highly cell type-specific, a signature of three microRNAs -miR-146a, miR-708 and miR-1246, emerges as consistently responsive to T. cruzi infection across representative human cell types. T. cruzi lacks canonical microRNA-induced silencing mechanisms and we confirm that it does not produce any small RNA that mimics known host microRNAs. We found that macrophages show a broad response to parasite infection, while microRNA changes in epithelial and cardiomyocytes are modest. Complementary data indicated that cardiomyocyte response may be greater at early time points of infection.

Conclusions

Our findings emphasize the significance of considering microRNA changes at the cellular level and complement previous studies conducted at higher organizational levels, such as heart samples. While miR-146a has been previously implicated in T. cruzi infection, similarly to its involvement in many other immunological responses, miR-1246 and miR-708 are demonstrated here for the first time. Given their expression in multiple cell types, we anticipate our work as a starting point for future investigations into their role in the post-transcriptional regulation of T. cruzi infected cells and their potential as biomarkers for Chagas disease.

Skeletal Muscle MicroRNA Patterns in Response to a Single Bout of Exercise in Females: Biomarkers for Subsequent Training Adaptation?

microRNAs (miRs) have been proposed as a promising new class of biomarkers in the context of training adaptation. Using microarray analysis, we studied skeletal muscle miR patterns in sedentary young healthy females (n = 6) before and after a single submaximal bout of endurance exercise ('reference training'). Subsequently, participants were subjected to a structured training program, consisting of six weeks of moderate-intensity continuous endurance training (MICT) and six weeks of high-intensity interval training (HIIT) in randomized order. In vastus lateralis muscle, we found significant downregulation of myomiRs, specifically miR-1, 133a-3p, and -5p, -133b, and -499a-5p. Similarly, exercise-associated miRs-23a-3p, -378a-5p, -128-3p, -21-5p, -107, -27a-3p, -126-3p, and -152-3p were significantly downregulated, whereas miR-23a-5p was upregulated. Furthermore, in an untargeted approach for differential expression in response to acute exercise, we identified n = 35 miRs that were downregulated and n = 20 miRs that were upregulated by factor 4.5 or more. Remarkably, KEGG pathway analysis indicated central involvement of this set of miRs in fatty acid metabolism. To reproduce these data in a larger cohort of all-female subjects (n = 29), qPCR analysis was carried out on n = 15 miRs selected from the microarray, which confirmed their differential expression. Furthermore, the acute response, i.e., the difference between miR concentrations before and after the reference training, was correlated with changes in maximum oxygen uptake (V̇O₂max) in response to the training program. Here, we found that miRs-199a-3p and -19b-3p might be suitable acute-response candidates that correlate with individual degrees of training adaptation in females.

Genomic and Epigenetic Changes Drive Aberrant Skeletal Muscle Differentiation in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS), the most common soft-tissue sarcoma in children and adolescents, represents an aberrant form of skeletal muscle differentiation. Both skeletal muscle development, as well as regeneration of adult skeletal muscle are governed by members of the myogenic family of regulatory transcription factors (MRFs), which are deployed in a highly controlled, multi-step, bidirectional process. Many aspects of this complex process are deregulated in RMS and contribute to tumorigenesis. Interconnected loops of super-enhancers, called core regulatory circuitries (CRCs), define aberrant muscle differentiation in RMS cells. The transcriptional regulation of MRF expression/activity takes a central role in the CRCs active in skeletal muscle and RMS. In PAX3::FOXO1 fusion-positive (PF+) RMS, CRCs maintain expression of the disease-driving fusion oncogene. Recent single-cell studies have revealed hierarchically organized subsets of cells within the RMS cell pool, which recapitulate developmental myogenesis and appear to drive malignancy. There is a large interest in exploiting the causes of aberrant muscle development in RMS to allow for terminal differentiation as a therapeutic strategy, for example, by interrupting MEK/ERK signaling or by interfering with the epigenetic machinery controlling CRCs. In this review, we provide an overview of the genetic and epigenetic framework of abnormal muscle differentiation in RMS, as it provides insights into fundamental mechanisms of RMS malignancy, its remarkable phenotypic diversity and, ultimately, opportunities for therapeutic intervention.

Clinical implications of circulating follistatin-like protein-1 in hemodialysis patients

Follistatin-like protein-1 (FSTL-1) is secreted glycoprotein, which regulates cardiovascular, immune and skeletal system. However, the clinical significance of circulating FSTL-1 levels remains unclear in hemodialysis patients. A total 376 hemodialysis patients were enrolled from June 2016 to March 2020. Plasma FSTL-1 level, inflammatory biomarkers, physical performance, and echocardiographic findings at baseline were examined. Plasma FSTL-1 levels were positively correlated with TNF-α and MCP-1. Handgrip strength showed weak positive correlation in male patients only, and gait speed showed no correlation with FSTL-1 levels. In multivariate linear regression analysis, FSTL-1 level was negatively associated with left ventricular ejection fraction (β =  - 0.36; p = 0.011). The cumulative event rate of the composite of CV event and death, and cumulative event rate of CV events was significantly greater in FSTL-1 tertile 3. In multivariate Cox-regression analysis, FSTL-1 tertile 3 was associated with a 1.80-fold risk for the composite of CV events and death(95% confidence interval (CI) 1.06-3.08), and a 2.28-fold risk for CV events (95% CI 1.15-4.51) after adjustment for multiple variables. In conclusion, high circulating FSTL-1 levels independently predict the composite of CV events and death, and FSTL-1 level was independently associated with left ventricular systolic dysfunction.

Diversity and Differential Expression of MicroRNAs in the Human Skeletal Muscle with Distinct Fiber Type Composition

The ratio of fast- and slow-twitch fibers in human skeletal muscle is variable and largely determined by genetic factors. In this study, we investigated the contribution of microRNA (miRNA) in skeletal muscle fiber type composition. The study involved biopsy samples of the vastus lateralis muscle from 24 male participants with distinct fiber type ratios. The miRNA study included samples from five endurance athletes and five power athletes with the predominance of slow-twitch (61.6-72.8%) and fast-twitch (69.3-80.7%) fibers, respectively. Total and small RNA were extracted from tissue samples. Total RNA sequencing (N = 24) revealed 352 differentially expressed genes between the groups with the predominance of fast- and slow-twitch muscle fibers. Small RNA sequencing showed upregulation of miR-206, miR-501-3p and miR-185-5p, and downregulation of miR-499a-5p and miR-208-5p in the group of power athletes with fast-twitch fiber predominance. Two miRtronic miRNAs, miR-208b-3p and miR-499a-5p, had strong correlations in expression with their host genes (MYH7 and MYH7B, respectively). Correlations between the expression of miRNAs and their experimentally validated messenger RNA (mRNA) targets were calculated, and 11 miRNA-mRNA interactions with strong negative correlations were identified. Two of them belonged to miR-208b-3p and miR-499a-5p, indicating their regulatory links with the expression of CDKN1A and FOXO4, respectively.

Modulation of the Circulating Extracellular Vesicles in Response to Different Exercise Regimens and Study of Their Inflammatory Effects

Exercise-released extracellular vesicles (EVs) are emerging as a novel class of exerkines that promotes systemic beneficial effects. However, slight differences in the applied exercise protocols in terms of mode, intensity and duration, as well as the need for standardized protocols for EV isolation, make the comparison of the studies in the literature extremely difficult. This work aims to investigate the EV amount and EV-associated miRNAs released in circulation in response to different physical exercise regimens. Healthy individuals were subjected to different exercise protocols: acute aerobic exercise (AAE) and training (AT), acute maximal aerobic exercise (AMAE) and altitude aerobic training (AAT). We found a tendency for total EVs to increase in the sedentary condition compared to trained participants following AAE. Moreover, the cytofluorimetric analysis showed an increase in CD81⁺/SGCA⁺/CD45^- EVs in response to AAE. Although a single bout of moderate/maximal exercise did not impact the total EV number, EV-miRNA levels were affected as a result. In detail, EV-associated miR-206, miR-133b and miR-146a were upregulated following AAE, and this trend appeared intensity-dependent. Finally, THP-1 macrophage treatment with exercise-derived EVs induced an increase of the mRNAs encoding for IL-1β, IL-6 and CD163 using baseline and immediately post-exercise EVs. Still, 1 h post-exercise EVs failed to stimulate a pro-inflammatory program. In conclusion, the reported data provide a better understanding of the release of circulating EVs and their role as mediators of the inflammatory processes associated with exercise.

Going nuclear: Molecular adaptations to exercise mediated by myonuclei

Muscle fibers are multinucleated, and muscle fiber nuclei (myonuclei) are believed to be post-mitotic and are typically situated near the periphery of the myofiber. Due to the unique organization of muscle fibers and their nuclei, the cellular and molecular mechanisms regulating myofiber homeostasis in unstressed and stressed conditions (e.g., exercise) are unique. A key role myonuclei play in regulating muscle during exercise is gene transcription. Only recently have investigators had the capability to identify molecular changes at high resolution exclusively in myonuclei in response to perturbations in vivo. The purpose of this review is to describe how myonuclei modulate their transcriptome, epigenetic status, mobility and shape, and microRNA expression in response to exercise in vivo. Given the relative paucity of high-fidelity information on myonucleus-specific contributions to exercise adaptation, we identify specific gaps in knowledge and provide perspectives on future directions of research.

MicroRNAs in Cancer and Cardiovascular Disease

Although cardiac tumor formation is rare, accumulating evidence suggests that the two leading causes of deaths, cancers, and cardiovascular diseases are similar in terms of pathogenesis, including angiogenesis, immune responses, and fibrosis. These similarities have led to the creation of new exciting field of study called cardio-oncology. Here, we review the similarities between cancer and cardiovascular disease from the perspective of microRNAs (miRNAs). As miRNAs are well-known regulators of translation by binding to the 3'-untranslated regions (UTRs) of messenger RNAs (mRNAs), we carefully dissect how a specific set of miRNAs are both oncomiRs (miRNAs in cancer) and myomiRs (muscle-related miRNAs). Furthermore, from the standpoint of similar pathogenesis, miRNAs categories related to the similar pathogenesis are discussed; namely, angiomiRs, Immune-miRs, and fibromiRs.

Role of exosomes and exosomal microRNA in muscle–Kidney crosstalk in chronic kidney disease

Chronic kidney disease (CKD) is a progressive damage of kidneys that can no longer serve the blood-filtering function, and is a life-threatening condition. Skeletal muscle wasting is a common complication of CKD. Yet the relationship between kidney and skeletal muscle in CKD remains unclear. Exosomes, a type of small membrane-bound vesicles released from cells to the extracellular environment, have increasingly received attention due to their potential as mediators of crosstalk between kidneys and different organs, including skeletal muscle. This mini-review summarizes the recent findings that point to the role of exosomes in the cross-talk between kidney and skeletal muscle in CKD. Understanding of the contents and the mechanism of exosome release may prone exosomes be the potential therapeutic targets for CKD.

Transforming Growth Factor-Beta Signaling in Cancer-Induced Cachexia: From Molecular Pathways to the Clinics

Cachexia is a metabolic syndrome consisting of massive loss of muscle mass and function that has a severe impact on the quality of life and survival of cancer patients. Up to 20% of lung cancer patients and up to 80% of pancreatic cancer patients are diagnosed with cachexia, leading to death in 20% of them. The main drivers of cachexia are cytokines such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), macrophage inhibitory cytokine 1 (MIC-1/GDF15) and transforming growth factor-beta (TGF-β). Besides its double-edged role as a tumor suppressor and activator, TGF-β causes muscle loss through myostatin-based signaling, involved in the reduction in protein synthesis and enhanced protein degradation. Additionally, TGF-β induces inhibin and activin, causing weight loss and muscle depletion, while MIC-1/GDF15, a member of the TGF-β superfamily, leads to anorexia and so, indirectly, to muscle wasting, acting on the hypothalamus center. Against this background, the blockade of TGF-β is tested as a potential mechanism to revert cachexia, and antibodies against TGF-β reduced weight and muscle loss in murine models of pancreatic cancer. This article reviews the role of the TGF-β pathway and to a minor extent of other molecules including microRNA in cancer onset and progression with a special focus on their involvement in cachexia, to enlighten whether TGF-β and such other players could be potential targets for therapy.

Epigenetic Alterations in Sports-Related Injuries

It is a well-known fact that physical activity benefits people of all age groups. However, highly intensive training, maladaptation, improper equipment, and lack of sufficient rest lead to contusions and sports-related injuries. From the perspectives of sports professionals and those performing regular–amateur sports activities, it is important to maintain proper levels of training, without encountering frequent injuries. The bodily responses to physical stress and intensive physical activity are detected on many levels. Epigenetic modifications, including DNA methylation, histone protein methylation, acetylation, and miRNA expression occur in response to environmental changes and play fundamental roles in the regulation of cellular activities. In the current review, we summarise the available knowledge on epigenetic alterations present in tissues and organs (e.g., muscles, the brain, tendons, and bones) as a consequence of sports-related injuries. Epigenetic mechanism observations have the potential to become useful tools in sports medicine, as predictors of approaching pathophysiological alterations and injury biomarkers that have already taken place.

Non-coding RNA in rhabdomyosarcoma progression and metastasis

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma of skeletal muscle differentiation, with a predominant occurrence in children and adolescents. One of the major challenges facing treatment success is the presence of metastatic disease at the time of diagnosis, commonly associated with the more aggressive fusion-positive subtype. Non-coding RNA (ncRNA) can regulate gene transcription and translation, and their dysregulation has been associated with cancer development and progression. MicroRNA (miRNA) are short non-coding nucleic acid sequences involved in the regulation of gene expression that act by targeting messenger RNA (mRNA), and their aberrant expression has been associated with both RMS initiation and progression. Other ncRNA including long non-coding RNA (lncRNA), circular RNA (circRNA) and ribosomal RNA (rRNA) have also been associated with RMS revealing important mechanistic roles in RMS biology, but these studies are still limited and require further investigation. In this review, we discuss the established roles of ncRNA in RMS differentiation, growth and progression, highlighting their potential use in RMS prognosis, as therapeutic agents or as targets of treatment.

MicroRNA-206 inhibits HCV proliferation through depressing ACC1 lipid synthesis signalling pathway

MicroRNAs are considered to play important roles in cell biological and pathological progress. microRNA-206 (miR-206) was reported to participate in lipogenesis, and lipid droplets were necessary for the life cycle of HCV proliferation. Whether miR-206 was associated with HCV proliferation and the potential mechanism are not clear. In this study, we firstly identified that miR-206 could inhibit HCV proliferation at the RNA and protein level. Bioinformatical prediction of target genes binding to miR-206 was performed to investigate whether inhibiting function was due to a lipogenesis pathway. Then, the acetyl-CoA carboxylase 1 (ACC1) gene was selected as target gene of miR-206. The dual-luciferase reporter assay results showed that luciferase significantly decreased in cells transfected with 3'-UTR of the ACC1 gene and miR-206. The RNA and protein levels of the ACC1 gene and its pathway genes were significantly lower in cells transfected with miR-206 than in controls. Furthermore, the lipid droplet numbers also significantly decreased in cells transfected with miR-206. In conclusion, miR-206 could inhibit HCV proliferation through depressing ACC1 lipogenesis pathway and decreasing the lipid droplet numbers. miR-206 might be used as anti-HCV biochemical drug in the future.

Serum microRNA miR-491-5p/miR-206 Is Correlated with Poor Outcomes/Spontaneous Hemorrhagic Transformation after Ischemic Stroke: A Case Control Study

Background: It is unclear whether miR-491-5p, miR-206, miR-21-5p or miR-3123 are associated with functional outcomes and hemorrhagic transformation (HT) after acute ischemic stroke (AIS). In this study, we aimed to investigate the correlation between these four microRNAs and functional outcomes, as well as spontaneous HT after AIS; Methods: We included 215 AIS patients and retrospectively assayed for miR-21-5p, miR-206, miR-3123 and miR-491-5p levels in serum. Poor functional outcome was defined as a modified Rankin Scale score ≥ 3. Spontaneous HT referred to hemorrhage detected in follow-up brain imaging but not on admission, without reperfusion therapies. Logistic regression, generalized additive model and 2-piecewise regression model were used to explore the independent, non-linear correlation between miRNA expression levels and outcomes; Results: We included 215 AIS patients. Higher miR-491-5p level independently reduced the risk of poor functional outcomes at 1 year (OR 0.90, 95% CI 0.82–0.98, corrected p value = 0.044). Higher miR-206 level significantly increased the risk of spontaneous HT (OR 1.64, 95% CI 1.17–2.30, corrected p value = 0.016). There was a nonlinear correlation found between miR-491-5p level and 1 year outcome with an inflection point of 2.180, while an approximately linear correlation was observed with an inflection point of 2.037 between miR-206 level and spontaneous HT; Conclusions: Higher serum miR-491-5p level independently reduced risk of 1-year poor functional outcome of AIS patients. Higher serum miR-206 level independently increased the risk of spontaneous HT in AIS patients. These two miRNAs may be as the potential biomarkers for improving prognosis after AIS.

MicroRNAs as serum biomarkers in Becker muscular dystrophy

Becker muscular dystrophy (BMD) is an X‐linked neuromuscular disorder due to mutation in the DMD gene, encoding dystrophin. Despite a wide clinical variability, BMD is characterized by progressive muscle degeneration and proximal muscle weakness. Interestingly, a dysregulated expression of muscle‐specific microRNAs (miRNAs), called myomirs, has been found in patients affected with muscular dystrophies, although few studies have been conducted in BMD. We analysed the serum expression levels of a subset of myomirs in a cohort of 29 ambulant individuals affected by BMD and further classified according to the degree of alterations at muscle biopsy and in 11 age‐matched healthy controls. We found a significant upregulation of serum miR‐1, miR‐133a, miR‐133b and miR‐206 in our cohort of BMD patients, supporting the role of these miRNAs in the pathophysiology of the disease, and we identified serum cut‐off levels discriminating patients from healthy controls, confiming the potential of circulating miRNAs as promising noninvasive biomarkers. Moreover, serum levels of miR‐133b were found to be associated with fibrosis at muscle biopsy and with patients' motor performances, suggesting that miR‐133b might be a useful prognostic marker for BMD patients. Taken together, our data showed that these serum myomirs may represent an effective tool that may support stratification of BMD patients, providing the opportunity of both monitoring disease progression and assessing the treatment efficacy in the context of clinical trials.

MicroRNAs in Dystrophinopathy

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), which represent the range of dystrophinopathies, account for nearly 80% of muscle dystrophy. DMD and BMD result from the loss of a functional dystrophin protein, and the leading cause of death in these patients is cardiac remodeling and heart failure. The pathogenesis and progression of the more severe form of DMD have been extensively studied and are controlled by many determinants, including microRNAs (miRNAs). The regulatory role of miRNAs in muscle function and the differential miRNA expression in muscular dystrophy indicate the clinical significance of miRNAs. This review discusses the relevant microRNAs as potential biomarkers and therapeutic targets for DMD and DMD cardiomyopathy as examples of dystrophinopathies.

Diagnostic and Prognostic Value Analysis of miR-206 in Asymptomatic Carotid Artery Stenosis

Introduction: To investigate the expression level of miR-206 in serum of patients with asymptomatic carotid artery stenosis (CAS) and estimate the value of miR-206 in the diagnosis and prognosis of asymptomatic CAS.

Methods: A total of 206 individuals enrolled in this study, including 105 CAS patients and 101 controls. RT-qPCR technology was applied to measure the relative level of miR-206, and Pearson’s correlation coefficient was performed to analyze the relationship between carotid artery stenosis degree and miR-206 level. An ROC curve was drawn to assess the diagnostic value of miR-206 in asymptomatic CAS. The 5-year prognosis of asymptomatic CAS patients was tested using multivariate Cox regression analysis and Kaplan-Meier survival curve.

Results: MiR-206 expression was reduced in asymptomatic CAS patients. The AUC of the ROC curve of miR-206 was 0.939, with a sensitivity of 86.70% and a specificity of 86.14%. The amount of CAS gradually increased with the decrease of miR-206 level. Seven-teen patients in the low miR-206 expression group developed CIEs, and 3 patients in the high miR-206 expression group developed CIEs during the 5-year follow-up. miR-206 and the amount of CAS were independent factors for the occurrence of CIEs within 5 years in asymptomatic CAS patients.

Conclusion: Serum miR-206 has high diagnostic accuracy for asymptomatic CAS and has predictive value for the incidence of CIEs in patients within 5 years.

MicroRNA expression signature in the striated and smooth adductor muscles of Yesso scallop Patinopecten yessoensis

Increasing evidences point to the potential role of microRNAs (miRNAs) in muscle growth and development in animals. However, knowledge on the identity of miRNAs and their targets in molluscs remains largely unknown. Scallops have one large adductor muscle, composed of fast (striated) and slow (smooth) muscle types, which display great differences in muscle fibers, meat quality, cell types and molecular components. In the present study, we performed a comprehensive investigation of miRNA transcriptomes in fast and slow adductor muscles of Yesso scallop Patinopecten yessoensis. As a result, 47 differentially expressed miRNAs representing ten miRNA families were identified between the striated and smooth adductor muscles. The KEGG enrichment analysis of their target genes were mainly associated with amino acid metabolism, energy metabolism and glycan biosynthesis. The target genes of miR-133 and miR-71 were validated by the dual-luciferase reporter assays and miRNA antagomir treatment in vivo. The identification and functional validation of these different miRNAs in scallops will greatly help our understanding of miRNA regulatory mechanism that achieves the unique muscle phenotypes in scallops. The present findings provide the direct evidences for muscle-specific miRNAs involved in muscle growth and differentiation in molluscs.

Men and women display distinct extracellular vesicle biomarker signatures in response to military operational stress

Extracellular vesicles (EVs) are mediators of physiological changes that occur during physical exertion. This study examined the effects of physical exertion with and without sleep and caloric restriction on EV size, concentration, and surface proteins in men and women. Twenty participants (10 men) completed a 5-day simulated military operational stress protocol with daily physical exertion. Blood was drawn before and immediately after exertion at baseline (D1) and following 48-h of sleep and caloric restriction (D3). EV size and concentration were assessed using nanoparticle tracking analysis. EVs were identified with markers associated with exosomes (CD63), microvesicles (VAMP3), apoptotic bodies (THSD1), and skeletal muscle-derived EVs (SGCA) and quantified using imaging flow cytometry. Interactive and main effects of sex, day, and time on EVs were assessed using three-way ANOVAs. EV concentration declined pre to postexertion in women on D1 and D3 but was stable in men. EV size increased from pre to postexertion and from D1 to D3 in men and women. Physical exertion following sleep and caloric restriction increased CD63+ EV concentration, proportion of total EVs, and CD63 surface protein expression regardless of sex. The proportion of SGCA+ EVs increased in men and women following exertion and from D1 to D3 but was higher in women than in men. No differences were observed in VAMP3+ and THSD1+ EVs. This study identified sexually dimorphic EV profiles in response to various stressors. Further investigations are necessary to determine if dimorphic EV responses affect health and performance outcomes during stress.NEW & NOTEWORTHY Sex is understudied in EV research, and most studies limit EV analysis to single stress conditions such as exercise. Multistress conditions consisting of physical exertion and sleep and caloric restriction are common in real-world settings. We demonstrate that physical exertion results in sex-specific EV signatures and that EV profiles vary according to single versus multistress conditions. Our data highlight important biological and ecological characteristics that should be considered in EV research.

Pleomorphic adenoma gene 1 (PLAG1) promotes proliferation and inhibits apoptosis of bovine primary myoblasts through the PI3K-Akt signaling pathway

Pleomorphic adenoma gene 1 (PLAG1) is a transcription factor involved in various cellular processes in organismal growth and development. However, its role in muscle function is unclear. This work investigated the roles of PLAG1 in muscle development and explored its regulatory mechanisms. The PLAG1 was proved to promote the proliferation of bovine primary myoblasts using the cell counting kit 8 (CCK-8) assay (P < 0.001), 5-ethynyl-2'-deoxyuridine (EdU) proliferation assay (P = 0.005), quantitative real-time polymerase chain reaction (qRT-PCR) (P = 0.028), western blot, and flow cytometry (P < 0.05), and to inhibit apoptosis of bovine primary myoblasts using qRT-PCR (P = 0.038), western blot, and flow cytometry (P < 0.001). Chromatin immunoprecipitation sequencing (ChIP-seq) and western blot showed PLAG1 upregulated phosphorylated (p)-PI3K, PI3K, p-Akt, Akt, Cyclin D1, and CDK2 and inhibited the expression of p21 and p27 to enhance myoblast proliferation, and increased expression of Bcl-2, and Bcl-xL to inhibit apoptosis. Additionally, PLAG1 was identified as a target of miR-1 using dual-luciferase assay (P < 0.001), qRT-PCR (P < 0.001), and western blot. Furthermore, miR-1 might be a potential mediator of the positive feedback regulation relationship between PLAG1 and the PI3K-Akt signaling pathway.

MicroRNA regulatory networks associated with abnormal muscle repair in survivors of critical illness

BACKGROUND

Intensive care unit (ICU)-acquired weakness is characterized by muscle atrophy and impaired contractility that may persist after ICU discharge. Dysregulated muscle repair and regeneration gene co-expression networks are present in critical illness survivors with persistent muscle wasting and weakness. We aimed to identify microRNAs (miRs) regulating the gene networks and determine their role in the self-renewal of muscle in ICU survivors.

METHODS

Muscle whole-transcriptome expression was assessed with microarrays in banked quadriceps biopsies obtained at 7 days and 6 months post-ICU discharge from critically ill patients (n = 15) in the RECOVER programme and healthy individuals (n = 8). We conducted an integrated miR-messenger RNA analysis to identify miR/gene pairs associated with muscle recovery post-critical illness and evaluated their impact on myoblast proliferation and differentiation in human AB1167 and murine C2C12 cell lines in vitro. Select target genes were validated with quantitative PCR.

RESULTS

Twenty-two miRs were predicted to regulate the Day 7 post-ICU muscle transcriptome vs. controls. Thirty per cent of all differentially expressed genes shared a 3'UTR regulatory sequence for miR-424-3p/5p, which was 10-fold down-regulated in patients (P < 0.001) and correlated with quadriceps size (R = 0.86, P < 0.001), strength (R = 0.75, P = 0.007), and physical function (Functional Independence Measures motor subscore, R = 0.92, P < 0.001) suggesting its potential role as a master regulator of early recovery of muscle mass and strength following ICU discharge. Network analysis demonstrated enrichment for cellular respiration and muscle fate commitment/development related genes. At 6 months post-ICU discharge, a 14-miR expression signature, including miRs-490-3p and -744-5p, identified patients with muscle mass recovery vs. those with sustained atrophy. Constitutive overexpression of the novel miR-490-3p significantly inhibited AB1167 and C2C12 myoblast proliferation (cell count AB1167 miR-490-3p mimic or scrambled-miR transfected myoblasts 7926 ± 4060 vs. 14 159 ± 3515 respectively, P = 0.006; proportion Ki67-positive nuclei AB1167 miR-490-3p mimic or scrambled-miR transfected myoblasts 0.38 ± 0.07 vs. 0.54 ± 0.06 respectively, P < 0.001; proliferating cell nuclear antigen expression AB1167 miR-490-3p mimic or scrambled-miR transfected myoblasts 11.48 ± 1.97 vs. 16.75 ± 1.19 respectively, P = 0.040). Constitutive overexpression of miR-744-5p, a known regulator of myogenesis, significantly inhibited AB1167 and C2C12 myoblast differentiation (fusion index AB1167 miR-744-5p mimic or scrambled-miR transfected myoblasts 8.31 ± 7.00% vs. 40.29 ± 9.37% respectively, P < 0.001; myosin heavy chain expression miR-744-5p mimic or scrambled-miR transfected myoblasts 0.92 ± 0.39 vs. 13.53 ± 5.5 respectively, P = 0.01).

CONCLUSIONS

Combined functional transcriptomics identified 36 miRs including miRs-424-3p/5p, -490-3p, and -744-5p as potential regulators of gene networks associated with recovery of muscle mass and strength following critical illness. MiR-490-3p is identified as a novel regulator of myogenesis.

Circular RNA circUSP13 sponges miR-29c to promote differentiation and inhibit apoptosis of goat myoblasts by targeting IGF1

Circular RNAs (circRNAs) are an indispensable element of post-transcriptional gene regulation, influencing a variety of biological processes including myogenic differentiation; however, little is known about the function of circRNA in goat myogenic differentiation. Using RNA-sequencing data from our laboratory, we explored the influences of circUSP13, as a candidate circRNA, on myoblast differentiation since its expression is higher in myoblasts of lamb (first day of age) than that of the fetus (75th day of pregnancy). In in vitro experiments, circUSP13 significantly promoted differentiation and inhibited apoptosis in goat primary myoblasts. Mechanistically, circUSP13 localized with miR-29c in the cytoplasm of goat myoblasts to regulate IGF1 expression. We further demonstrated that circUSP13 sponges miR-29c, promoting IGF1 expression that upregulated the expression of MyoG and MyHC. Thus, our results identified circUSP13 as a molecular marker for breeding programs of mutton production, as well as the circUSP13-miR-29c-IGF1 axis as a potential therapeutic target for combating muscle wasting.

TGF-β Induction of miR-143/145 Is Associated to Exercise Response by Influencing Differentiation and Insulin Signaling Molecules in Human Skeletal Muscle

Physical training improves insulin sensitivity and can prevent type 2 diabetes (T2D). However, approximately 20% of individuals lack a beneficial outcome in glycemic control. TGF-β, identified as a possible upstream regulator involved in this low response, is also a potent regulator of microRNAs (miRNAs). The aim of this study was to elucidate the potential impact of TGF-β-driven miRNAs on individual exercise response. Non-targeted long and sncRNA sequencing analyses of TGF-β1-treated human skeletal muscle cells corroborated the effects of TGF-β1 on muscle cell differentiation, the induction of extracellular matrix components, and identified several TGF-β1-regulated miRNAs. qPCR validated a potent upregulation of miR-143-3p/145-5p and miR-181a2-5p by TGF-β1 in both human myoblasts and differentiated myotubes. Healthy subjects who were overweight or obese participated in a supervised 8-week endurance training intervention (n = 40) and were categorized as responder or low responder in glycemic control based on fold change ISIMats (≥+1.1 or <+1.1, respectively). In skeletal muscle biopsies of low responders, TGF-β signaling and miR-143/145 cluster levels were induced by training at much higher rates than among responders. Target-mining revealed HDACs, MYHs, and insulin signaling components INSR and IRS1 as potential miR-143/145 cluster targets. All these targets were down-regulated in TGF-β1-treated myotubes. Transfection of miR-143-3p/145-5p mimics in differentiated myotubes validated MYH1, MYH4, and IRS1 as miR-143/145 cluster targets. Elevated TGF-β signaling and miR-143/145 cluster induction in skeletal muscle of low responders might obstruct improvements in insulin sensitivity by training in two ways: by a negative impact of miR-143-3p on muscle cell fusion and myofiber functionality and by directly impairing insulin signaling via a reduction in INSR by TGF-β and finetuned IRS1 suppression by miR-143-3p.

Age-Related Exosomal and Endogenous Expression Patterns of miR-1, miR-133a, miR-133b, and miR-206 in Skeletal Muscles

Skeletal muscle growth and maintenance depend on two tightly regulated processes, myogenesis and muscle regeneration. Both processes involve a series of crucial regulatory molecules including muscle-specific microRNAs, known as myomiRs. We recently showed that four myomiRs, miR-1, miR-133a, miR-133b, and miR-206, are encapsulated within muscle-derived exosomes and participate in local skeletal muscle communication. Although these four myomiRs have been extensively studied for their function in muscles, no information exists regarding their endogenous and exosomal levels across age. Here we aimed to identify any age-related changes in the endogenous and muscle-derived exosomal myomiR levels during acute skeletal muscle growth. The four endogenous and muscle-derived myomiRs were investigated in five skeletal muscles (extensor digitorum longus, soleus, tibialis anterior, gastrocnemius, and quadriceps) of 2-week–1-year-old wild-type male mice. The expression of miR-1, miR-133a, and miR-133b was found to increase rapidly until adolescence in all skeletal muscles, whereas during adulthood it remained relatively stable. By contrast, endogenous miR-206 levels were observed to decrease with age in all muscles, except for soleus. Differential expression of the four myomiRs is also inversely reflected on the production of two protein targets; serum response factor and connexin 43. Muscle-derived exosomal miR-1, miR-133a, and miR-133b levels were found to increase until the early adolescence, before reaching a plateau phase. Soleus was found to be the only skeletal muscle to release exosomes enriched in miR-206. In this study, we showed for the first time an in-depth longitudinal analysis of the endogenous and exosomal levels of the four myomiRs during skeletal muscle development. We showed that the endogenous expression and extracellular secretion of the four myomiRs are associated to the function and size of skeletal muscles as the mice age. Overall, our findings provide new insights for the myomiRs’ significant role in the first year of life in mice.

Effects of Aerobic Exercise Training on MyomiRs Expression in Cachectic and Non-Cachectic Cancer Mice

We investigated the effects of AET on myomiRs expression in the skeletal muscle and serum of colon cachectic (CT26) and breast non-cachectic (MMTV-PyMT) cancer mice models. Colon cancer decreased microRNA-486 expression, increasing PTEN in tibialis anterior muscle (TA), decreasing the PI3K/mTOR protein pathway, body and muscle wasting, fibers' cross-sectional area and muscle dysfunction, that were not preserved by AET. In contrast, breast cancer decreased those muscle functions, but were preserved by AET. In circulation, the downregulation of microRNA-486 and -206 in colon cancer, and the downregulation of microRNA-486 and upregulation of microRNA-206 expression in breast cancer might be good cancer serum biomarkers. Since the microRNA-206 is skeletal muscle specific, their expression was increased in the TA, serum and tumor in MMTV, suggesting a communication among these three compartments. The AET prevents these effects on microRNA-206, but not on microRNA-486 in MMTV. In conclusion, cancer induced a downregulation of microRNA-486 expression in TA and serum of CT26 and MMTV mice and these effects were not prevented by AET; however, to MMTV, the trained muscle function was preserved, probably sustained by the downregulation of microRNA-206 expression. Serum microRNA-206 is a potential biomarker for colon (decreased) and breast (increased) cancer to monitor the disease evolution and the effects promoted by the AET.

Circulating miRNA repertoire as a biomarker of metabolic and reproductive states in rainbow trout

Background

Circulating miRNAs (c-miRNAs) are found in most, if not all, biological fluids and are becoming well-established non-invasive biomarkers of many human pathologies. However, their features in non-pathological contexts and whether their expression profiles reflect normal life history events have received little attention, especially in non-mammalian species. The aim of the present study was to investigate the potential of c-miRNAs to serve as biomarkers of reproductive and metabolic states in fish.

Results

The blood plasma was sampled throughout the reproductive cycle of female rainbow trout subjected to two different feeding regimes that triggered contrasting metabolic states. In addition, ovarian fluid was sampled at ovulation, and all samples were subjected to small RNA-seq analysis, leading to the establishment of a comprehensive miRNA repertoire (i.e., miRNAome) and enabling subsequent comparative analyses to a panel of RNA-seq libraries from a wide variety of tissues and organs. We showed that biological fluid miRNAomes are complex and encompass a high proportion of the overall rainbow trout miRNAome. While sharing a high proportion of common miRNAs, the blood plasma and ovarian fluid miRNAomes exhibited strong fluid-specific signatures. We further revealed that the blood plasma miRNAome significantly changed depending on metabolic and reproductive states. We subsequently identified three evolutionarily conserved muscle-specific miRNAs or myomiRs (miR-1-1/2-3p, miR-133a-1/2-3p, and miR-206-3p) that accumulated in the blood plasma in response to high feeding rates, making these myomiRs strong candidate biomarkers of active myogenesis. We also identified miR-202-5p as a candidate biomarker for reproductive success that could be used to predict ovulation and/or egg quality.

Conclusions

Together, these promising results reveal the high potential of c-miRNAs, including evolutionarily conserved myomiRs, as physiologically relevant biomarker candidates and pave the way for the use of c-miRNAs for non-invasive phenotyping in various fish species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01163-5.

Therapeutic Implications of miRNAs for Muscle-Wasting Conditions

MicroRNAs (miRNAs) are small, non-coding RNA molecules that are mainly involved in translational repression by binding to specific messenger RNAs. Recently, miRNAs have emerged as biomarkers, relevant for a multitude of pathophysiological conditions, and cells can selectively sort miRNAs into extracellular vesicles for paracrine and endocrine effects. In the overall context of muscle-wasting conditions, a multitude of miRNAs has been implied as being responsible for the typical dysregulation of anabolic and catabolic pathways. In general, chronic muscle disorders are associated with the main characteristic of a substantial loss in muscle mass. Muscular dystrophies (MDs) are a group of genetic diseases that cause muscle weakness and degeneration. Typically, MDs are caused by mutations in those genes responsible for upholding the integrity of muscle structure and function. Recently, the dysregulation of miRNA levels in such pathological conditions has been reported. This revelation is imperative for both MDs and other muscle-wasting conditions, such as sarcopenia and cancer cachexia. The expression levels of miRNAs have immense potential for use as potential diagnostic, prognostic and therapeutic biomarkers. Understanding the role of miRNAs in muscle-wasting conditions may lead to the development of novel strategies for the improvement of patient management.

Targeting microRNAs with thymoquinone: a new approach for cancer therapy

Cancer is a global disease involving transformation of normal cells into tumor types via numerous mechanisms, with mortality among all generations, in spite of the breakthroughs in chemotherapy, radiotherapy and/or surgery for cancer treatment. Since one in six deaths is due to cancer, it is one of the overriding priorities of world health. Recently, bioactive natural compounds have been widely recognized due to their therapeutic effects for treatment of various chronic disorders, notably cancer. Thymoquinone (TQ), the most valuable constituent of black cumin seeds, has shown anti-cancer characteristics in a wide range of animal models. The revolutionary findings have revealed TQ's ability to regulate microRNA (miRNA) expression, offering a promising approach for cancer therapy. MiRNAs are small noncoding RNAs that modulate gene expression by means of variation in features of mRNA. MiRNAs manage several biological processes including gene expression and cellular signaling pathways. Accordingly, miRNAs can be considered as hallmarks for cancer diagnosis, prognosis and therapy. The purpose of this study was to review the various molecular mechanisms by which TQ exerts its potential as an anti-cancer agent through modulating miRNAs.