miR-206 family is important for mitochondrial and muscle function, but not essential for myogenesis in vitro

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.

Effect of miR-206 on lower limb ischemia-reperfusion injury in rat and its mechanism

Lower limb ischemia-reperfusion is a common pathological process during clinical surgery. Because lower limb ischemia-reperfusion usually aggravates ischemia-induced skeletal muscle tissue injury after lower limb ischemia-reperfusion, it also causes remote organ heart, intestine, liver, lung and other injuries, and there is no effective clinical treatment for lower limb ischemia-reperfusion injury, so it is urgent to study its injury mechanism. In this study, the rat model of lower limb ischemia-reperfusion was established by clamping the femoral artery with microarterial clips, and the wall destruction such as intimal injury, cell edema, collagen degeneration, neutrophil infiltration, and elastic fiberboard injury of the femoral artery wall was detected. The expression of inflammatory factors was detected by immunohistochemistry. miR-206 preconditioning was used to observe the expression of inflammatory factors, redox status and apoptosis in the vascular wall of rats after acute limb ischemia-reperfusion. Our findings suggest that vascular endothelial cell edema increases, wall thickening, neutrophil infiltration, and elastic fiber layer damage during IRI. Inflammatory factor expression was increased in femoral artery tissue, and miR-206 expression levels were significantly down-regulated. Further studies have found that miR-206 attenuates lower limb IRI by regulating the effects of phase inflammatory factors. In this study, we investigated the effect of miR-206 on inflammatory factors and its possible role in the development of lower limb IRI, providing new research ideas for the regulatory mechanism of lower limb IRI, and providing a certain theoretical basis for the treatment of lower limb ischemia-reperfusion injury after surgery or endovascular intervention.

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.

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.

Understanding the Roles and Regulation of Mitochondrial microRNAs (MitomiRs) in Neurodegenerative Diseases: Current Status and Advances

MicroRNAs (miRNA) are a class of small non-coding RNA, roughly 21 - 22 nucleotides in length, which are master gene regulators. These miRNAs bind to the mRNA's 3' - untranslated region and regulate post-transcriptional gene regulation, thereby influencing various physiological and cellular processes. Another class of miRNAs known as mitochondrial miRNA (MitomiRs) has been found to either originate from the mitochondrial genome or be translocated directly into the mitochondria. Although the role of nuclear DNA encoded miRNA in the progression of various neurological diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, etc. is well known, accumulating evidence suggests the possible role of deregulated mitomiRs in the progression of various neurodegenerative diseases with unknown mechanism. We have attempted to outline the current state of mitomiRs role in controlling mitochondrial gene expression and function through this review, paying particular attention to their contribution to neurological processes, their etiology, and their potential therapeutic use.

SMN promotes mitochondrial metabolic maturation during myogenesis by regulating the MYOD-miRNA axis

Spinal muscular atrophy (SMA) is a congenital neuromuscular disease caused by the mutation or deletion of the survival motor neuron 1 (SMN1) gene. Although the primary cause of progressive muscle atrophy in SMA has classically been considered the degeneration of motor neurons, recent studies have indicated a skeletal muscle-specific pathological phenotype such as impaired mitochondrial function and enhanced cell death. Here, we found that the down-regulation of SMN causes mitochondrial dysfunction and subsequent cell death in in vitro models of skeletal myogenesis with both a murine C2C12 cell line and human induced pluripotent stem cells. During myogenesis, SMN binds to the upstream genomic regions of MYOD1 and microRNA (miR)-1 and miR-206. Accordingly, the loss of SMN down-regulates these miRs, whereas supplementation of the miRs recovers the mitochondrial function, cell survival, and myotube formation of SMN-deficient C2C12, indicating the SMN-miR axis is essential for myogenic metabolic maturation. In addition, the introduction of the miRs into ex vivo muscle stem cells derived from Δ7-SMA mice caused myotube formation and muscle contraction. In conclusion, our data revealed novel transcriptional roles of SMN during myogenesis, providing an alternative muscle-oriented therapeutic strategy for SMA patients.

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.

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.

Identification and functional characterization of Pomstna in Japanese flounder (Paralichthys olivaceus)

Myostatin (MSTN) as a negative regulator of muscle growth has been identified in Japanese flounder. Yet, most fish experienced the teleost specific genome duplication and possess at least two mstn genes. In current study, the second mstn gene named Pomstna is identified in Japanese flounder. Pomstna is clustered with other mstn2 of teleosts and owned highly conserved TGF-beta domain. In addition to muscle, Pomstna also highly expressed in brain and spleen. Using the primarily cultured muscle cells of Japanese flounder, we found that Pomstna could inhibit the proliferation and differentiation of muscle cells in vitro. As a ligand of TGF-beta signaling pathway, Pomstnb could regulate the expression of p21 and myod by activating the TGF-beta signaling pathway. Different from the function of Pomstnb, Pomstna could not activate the TGF-beta signaling pathway in vitro. During the differentiation of PoM cells, the expression of Pomstnb decreased significantly but the expression of Pomstna showed no change. Our study suggests that Pomstna could negatively regulate the growth and differentiation of muscle like Pomstnb yet through a different regulatory mechanism than Pomstnb. The present study suggests that muscle proliferation and differentiation were regulated by mstn not only through the TGF-beta signaling pathway but also other unknown mechanisms.

miR-30a-3p can inhibit the proliferation and promote the differentiation of chicken primary myoblasts

1. Chicken muscle is an important factor in meat quality and its development is controlled by a complex regulatory network.2. The following study examined the expression of miR-30a-3p in Gushi chicken breast muscle tissue and found that it was differentially expressed at different embryonic stages, reaching a peak in the 14-day-old embryo (E14).3. The effect of miR-30a-3p on chicken primary myoblasts (CPMs) was explored. Results from both cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) showed that this can inhibit the proliferation of myoblasts, and through cell cycle experiments, the inhibition of myoblast proliferation was found, which may be due to G0/G1 arrest in the cell cycle.4. The effect of miR-30a-3p on the differentiation of myoblasts was studied. The results showed that miR-30a-3p can promote the expression of MYOD, myogenin (MYOG), and myosin heavy chain (MYHC) genes to promote the differentiation of myoblasts. Through MYHC protein immunofluorescence experiments, it was found that miR-30a-3p can effectively increase the area of myotubes.5. Finally, mRNA transcriptome data was analysed, which showed that miR-30a-3p has 51 potential target genes. Among them, forkhead box O3 (FOXO3), ankyrin repeat domain 1 (ANKRD1), and insulin-induced 1 (INSIG1) genes were differentially expressed at different developmental stages and were enriched in Gene Ontology (GO) terms, such as cell differentiation and cellular developmental process. The data showed that tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein gamma (YWHAG), BUB1 mitotic checkpoint serine/threonine kinase (BUB1), and growth arrest and DNA damage-inducible 45 (GADD45) genes were enriched in the cell cycle pathway.6. It can be speculated that miR-30a-3p plays roles through these genes in myoblast development. This research provides information for further improving knowledge of the chicken muscle development regulation network.

Non-Coding RNAs as Regulators of Myogenesis and Postexercise Muscle Regeneration

miRNAs and lncRNAs do not encode proteins, but they play an important role in the regulation of gene expression. They differ in length, biogenesis, and mode of action. In this work, we focus on the selected miRNAs and lncRNAs involved in the regulation of myogenesis and muscle regeneration. We present selected miRNAs and lncRNAs that have been shown to control myogenic differentiation and show that manipulation of their levels could be used to improve myogenic differentiation of various types of stem and progenitor cells. Finally, we discuss how physical activity affects miRNA and lncRNA expression and how it affects muscle well-being.

miR-1 sustains muscle physiology by controlling V-ATPase complex assembly

Muscle function requires unique structural and metabolic adaptations that can render muscle cells selectively vulnerable, with mutations in some ubiquitously expressed genes causing myopathies but sparing other tissues. We uncovered a muscle cell vulnerability by studying miR-1, a deeply conserved, muscle-specific microRNA whose ablation causes various muscle defects. Using Caenorhabditis elegans, we found that miR-1 represses multiple subunits of the ubiquitous vacuolar adenosine triphosphatase (V-ATPase) complex, which is essential for internal compartment acidification and metabolic signaling. V-ATPase subunits are predicted miR-1 targets in animals ranging from C. elegans to humans, and we experimentally validated this in Drosophila. Unexpectedly, up-regulation of V-ATPase subunits upon miR-1 deletion causes reduced V-ATPase function due to defects in complex assembly. These results reveal V-ATPase assembly as a conserved muscle cell vulnerability and support a previously unknown role for microRNAs in the regulation of protein complexes.

Identification of potential microRNAs and KEGG pathways in denervation muscle atrophy based on meta-analysis

The molecular mechanism of muscle atrophy has been studied a lot, but there is no comprehensive analysis focusing on the denervated muscle atrophy. The gene network that controls the development of denervated muscle atrophy needs further elucidation. We examined differentially expressed genes (DEGs) from five denervated muscle atrophy microarray datasets and predicted microRNAs that target these DEGs. We also included the differentially expressed microRNAs datasets of denervated muscle atrophy in previous studies as background information to identify potential key microRNAs. Finally, we compared denervated muscle atrophy with disuse muscle atrophy caused by other reasons, and obtained the Den-genes which only differentially expressed in denervated muscle atrophy. In this meta-analysis, we obtained 429 up-regulated genes, 525 down-regulated genes and a batch of key microRNAs in denervated muscle atrophy. We found eight important microRNA-mRNA interactions (miR-1/Jun, miR-1/Vegfa, miR-497/Vegfa, miR-23a/Vegfa, miR-206/Vegfa, miR-497/Suclg1, miR-27a/Suclg1, miR-27a/Mapk14). The top five KEGG pathways enriched by Den-genes are Insulin signaling pathway, T cell receptor signaling pathway, MAPK signaling pathway, Toll-like receptor signaling pathway and B cell receptor signaling pathway. Our research has delineated the RNA regulatory network of denervated muscle atrophy, and uncovered the specific genes and terms in denervated muscle atrophy.

MyomiRs and their multifaceted regulatory roles in muscle homeostasis and amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by loss of both upper and lower motor neurons (MNs). The main clinical features of ALS are motor function impairment, progressive muscle weakness, muscle atrophy and, ultimately, paralysis. Intrinsic skeletal muscle deterioration plays a crucial role in the disease and contributes to ALS progression. Currently, there are no effective treatments for ALS, highlighting the need to obtain a deeper understanding of the molecular events underlying degeneration of both MNs and muscle tissue, with the aim of developing successful therapies. Muscle tissue is enriched in a group of microRNAs called myomiRs, which are effective regulators of muscle homeostasis, plasticity and myogenesis in both physiological and pathological conditions. After providing an overview of ALS pathophysiology, with a focus on the role of skeletal muscle, we review the current literature on myomiR network dysregulation as a contributing factor to myogenic perturbations and muscle atrophy in ALS. We argue that, in view of their critical regulatory function at the interface between MNs and skeletal muscle fiber, myomiRs are worthy of further investigation as potential molecular targets of therapeutic strategies to improve ALS symptoms and counteract disease progression.

Small-RNA Sequencing Reveals Altered Skeletal Muscle microRNAs and snoRNAs Signatures in Weanling Male Offspring from Mouse Dams Fed a Low Protein Diet during Lactation

Maternal diet during gestation and lactation affects the development of skeletal muscles in offspring and determines muscle health in later life. In this paper, we describe the association between maternal low protein diet-induced changes in offspring skeletal muscle and the differential expression (DE) of small non-coding RNAs (sncRNAs). We used a mouse model of maternal protein restriction, where dams were fed either a normal (N, 20%) or a low protein (L, 8%) diet during gestation and newborns were cross-fostered to N or L lactating dams, resulting in the generation of NN, NL and LN offspring groups. Total body and tibialis anterior (TA) weights were decreased in weanling NL male offspring but were not different in the LN group, as compared to NN. However, histological evaluation of TA muscle revealed reduced muscle fibre size in both groups at weaning. Small RNA-sequencing demonstrated DE of multiple miRs, snoRNAs and snRNAs. Bioinformatic analyses of miRs-15a, -34a, -122 and -199a, in combination with known myomiRs, confirmed their implication in key muscle-specific biological processes. This is the first comprehensive report for the DE of sncRNAs in nutrition-associated programming of skeletal muscle development, highlighting the need for further research to unravel the detailed molecular mechanisms.

miR-206 enforces a slow muscle phenotype

Striated muscle is a highly specialized collection of tissues with contractile properties that vary according to functional needs. Although muscle fiber types are established postnatally, lifelong plasticity facilitates stimulus-dependent adaptation. Functional adaptation requires molecular adaptation, which is partially provided by miRNA-mediated post-transcriptional regulation. miR-206 is a muscle-specific miRNA enriched in slow muscles. We investigated whether miR-206 drives the slow muscle phenotype or is merely an outcome. We found that miR-206 expression increases in both physiological (including female sex and endurance exercise) and pathological conditions (muscular dystrophy and adrenergic agonism) that promote a slow phenotype. Consistent with that observation, the slow soleus muscle of male miR-206-knockout mice displays a faster phenotype than wild-type mice. Moreover, left ventricles of male miR-206 knockout mice have a faster myosin profile, accompanied by dilation and systolic dysfunction. Thus, miR-206 appears to be necessary to enforce a slow skeletal and cardiac muscle phenotype and to play a key role in muscle sexual dimorphisms.