miR-22 regulates C2C12 myoblast proliferation and differentiation by targeting TGFBR1

MicroRNA-542-3p targets Pten to inhibit the myoblasts proliferation but suppresses myogenic differentiation independent of targeted Pten

BACKGROUND

Non-coding RNA is a key epigenetic regulation factor during skeletal muscle development and postnatal growth, and miR-542-3p was reported to be conserved and highly expressed in the skeletal muscle among different species. However, its exact functions in the proliferation of muscle stem cells and myogenesis remain to be determined.

METHODS

Transfection of proliferative and differentiated C2C12 cells used miR-542-3p mimic and inhibitor. RT-qPCR, EdU staining, immunofluorescence staining, cell counting kit 8 (CCK-8), and Western blot were used to evaluate the proliferation and myogenic differentiation caused by miR-542-3p. The dual luciferase reporter analysis and rescued experiment of the target gene were used to reveal the molecular mechanism.

RESULTS

The data shows overexpression of miR-542-3p downregulation of mRNA and protein levels of proliferation marker genes, reduction of EdU+ cells, and cellular vitality. Additionally, knocking it down promoted the aforementioned phenotypes. For differentiation, the miR-542-3p gain-of-function reduced both mRNA and protein levels of myogenic genes, including MYOG, MYOD1, et al. Furthermore, immunofluorescence staining immunized by MYHC antibody showed that the myotube number, fluorescence intensity, differentiation index, and myotube fusion index all decreased in the miR-542-3p mimic group, compared with the control group. Conversely, these phenotypes exhibited an increased trend in the miR-542-3p inhibitor group. Mechanistically, phosphatase and tensin homolog (Pten) was identified as the bona fide target gene of miR-542-3p by dual luciferase reporter gene assay, si-Pten combined with miR-542-3p inhibitor treatments totally rescued the promotion of proliferation by loss-function of miR-542-3p.

CONCLUSIONS

This study indicates that miR-542-3p inhibits the proliferation and differentiation of myoblast and Pten is a dependent target gene of miR-542-3p in myoblast proliferation, but not in differentiation.

Exploring the Integrated Role of miRNAs and lncRNAs in Regulating the Transcriptional Response to Amino Acids and Insulin-like Growth Factor 1 in Gilthead Sea Bream (Sparus aurata) Myoblasts

In this study, gilthead sea bream (Sparus aurata) fast muscle myoblasts were stimulated with two pro-growth treatments, amino acids (AA) and insulin-like growth factor 1 (Igf-1), to analyze the transcriptional response of mRNAs, microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) and to explore their possible regulatory network using bioinformatic approaches. AA had a higher impact on transcription (1795 mRNAs changed) compared to Igf-1 (385 mRNAs changed). Both treatments stimulated the transcription of mRNAs related to muscle differentiation (GO:0042692) and sarcomere (GO:0030017), while AA strongly stimulated DNA replication and cell division (GO:0007049). Both pro-growth treatments altered the transcription of over 100 miRNAs, including muscle-specific miRNAs (myomiRs), such as miR-133a/b, miR-206, miR-499, miR-1, and miR-27a. Among 111 detected lncRNAs (>1 FPKM), only 30 were significantly changed by AA and 11 by Igf-1. Eight lncRNAs exhibited strong negative correlations with several mRNAs, suggesting a possible regulation, while 30 lncRNAs showed strong correlations and interactions with several miRNAs, suggesting a role as sponges. This work is the first step in the identification of the ncRNAs network controlling muscle development and growth in gilthead sea bream, pointing out potential regulatory mechanisms in response to pro-growth signals.

Transcriptome Analysis of miRNA and mRNA in Porcine Skeletal Muscle following Glaesserella parasuis Challenge

Glaesserella parasuis (G. parasuis) causes systemic infection in pigs, but its effects on skeletal muscle and underlying mechanisms are poorly understood. We investigated G. parasuis infection in colostrum-deprived piglets, observing decreased daily weight gain and upregulation of inflammatory factors in skeletal muscle. Muscle fiber area and diameter were significantly reduced in the treated group (n = 3) compared to the control group (n = 3), accompanied by increased expression of FOXO1, FBXO32, TRIM63, CTSL, and BNIP3. Based on mRNA and microRNA (miRNA) sequencing, we identified 1642 differentially expressed (DE) mRNAs and 19 known DE miRNAs in skeletal muscle tissues between the two groups. We predicted target genes with opposite expression patterns to the 19 miRNAs and found significant enrichment and activation of the FoxO signaling pathway. We found that the upregulated core effectors FOXO1 and FOXO4 were targeted by downregulated ssc-miR-486, ssc-miR-370, ssc-miR-615, and ssc-miR-224. Further investigation showed that their downstream upregulated genes involved in protein degradation were also targeted by the downregulated ssc-miR-370, ssc-miR-615, ssc-miR-194a-5p, and ssc-miR-194b-5p. These findings suggest that G. parasuis infection causes skeletal muscle atrophy in piglets through accelerated protein degradation mediated by the "miRNAs-FOXO1/4" axis, while further research is necessary to validate the regulatory relationships. Our results provide new insights into the understanding of systemic inflammation growth mechanisms caused by G. parasuis and the role of miRNAs in bacterial infection pathogenesis.

Bta-miR-181d and Bta-miR-196a mediated proliferation, differentiation, and apoptosis in Bovine Myogenic Cells

Skeletal muscle is an important component of livestock and poultry organisms. The proliferation and differentiation of myoblasts are highly coordinated processes, which rely on the regulation of miRNA. MiRNAs are widely present in organisms and play roles in various biological processes, including cell proliferation, differentiation, and apoptosis. MiR-181d and miR-196a, identified as tumor suppressors, have been found to be involved in cell proliferation, apoptosis, directed differentiation, and cancer cell invasion. However, their role in beef cattle skeletal muscle metabolism remains unclear. In this study, we discovered that overexpression of bta-miR-181d and bta-miR-196a in Qinchuan cattle myoblasts inhibited proliferation and apoptosis while promoting myogenic differentiation through EDU staining, flow cytometry analysis, immunofluorescence staining, and Western blotting. RNA-seq analysis of differential gene expression revealed that after overexpression of bta-miR-181d and bta-miR-196a, the differentially expressed genes were mainly enriched in the PI3K-Akt and MAPK signaling pathways. Furthermore, the phosphorylation levels of key proteins p-AKT in the PI3K signaling pathway and p-MAPK in the MAPK signaling pathway were significantly decreased after overexpression of bta-miR-181d and bta-miR-196a. Overall, this study provides preliminary evidence that bta-miR-181d and bta-miR-196a may regulate proliferation, apoptosis, and differentiation processes in Qinchuan cattle myoblasts by affecting the phosphorylation status of key proteins in PI3K-Akt and MAPK-ERK signaling pathways.

LncRNA LINC00847 Accelerates Melanoma Progression by Regulating MiR-133a-3p/TGFBR1 Axis

AIMS

Growing evidence has suggested that lncRNAs play a regulatory role in tumorigenesis. Dysregulation of a newly identified lncRNA (LINC00847) has been involved in several tumors. Nevertheless, the expression and roles of lncRNAs in skin melanoma remain unclear. Therefore, we attempted to investigate the expressions and roles of lncRNAs in this study.

MATERIALS AND METHODS

Expression levels of LINC00847 were quantified in tissue samples from the TCGA database and clinically recruited participants. LINC00847 was inhibited in cells by transfecting with si-LINC00847 or si-NC. Expressions of LINC00847 and miR-133a-3p were determined using RT-qPCR, and the TGFBR1 level was determined using Western blotting. Targeting sites of LINC00847 with miR-133a-3p and miR-133a-3p with TGFBR1 were predicted by bioinformatic tools and proved by dual-luciferase reporter system and RNA immunoprecipitation. Cell proliferation, invasion, and migration abilities were assessed using CCK8, cell colony formation, cell wound scratch, and transwell assay, respectively.

RESULTS

In both TCGA and clinical cohorts, the expression of LINC00847 was abnormally upregulated in skin melanoma tissues than that of benign nevus. Besides, LINC00847 expression increased more markedly in A375 and SK-MEL-28 cells than in normal epidermal melanocytes (HEMa-LP cells). LINC00847 knockdown remarkably restrained skin melanoma cell proliferation, metastasis, and wound healing rate. Furthermore, miR-133a-3p/TGFBR1 was the downstream target for LINC00847. LINC00847 negatively regulated miR-133a-3p expression in skin melanoma cells. Both miR-133a-3p inhibitors and TGFBR1 vector transfection reversed the effect of LINC00847 silence in skin melanoma cells.

CONCLUSION

LINC00847 was highly expressed in skin melanoma, and its overexpression accelerated the malignant tumor behavior of skin melanoma cells. The miR-133a-3p /TGFBR1 axis was involved in the roles of LINC00847 in skin melanoma.

Design and characterization of a novel tumor-homing cell-penetrating peptide for drug delivery in TGFBR3 high-expressing tumors

Targeted therapy has attracted more and more attention in cancer treatment in recent years. However, due to the diversity of tumor types and the mutation of target sites on the tumor surface, some existing targets are no longer suitable for tumor therapy. In addition, the long-term administration of a single targeted drug can also lead to drug resistance and attenuate drug potency, so it is important to develop new targets for tumor therapy. The expression of Type III transforming growth factor β receptor (TGFBR3) is upregulated in colon, breast, and prostate cancer cells, and plays an important role in the occurrence and development of these cancers, so TGFBR3 may be developed as a novel target for tumor therapy, but so far there is no report on this research. In this study, the structure of bone morphogenetic protein 4 (BMP4), one of the ligands of TGFBR3 was analyzed through the docking analysis with TGFBR3 and sequence charge characteristic analysis, and a functional tumor-targeting penetrating peptide T3BP was identified. The results of fluorescent labeling experiments showed that T3BP could target and efficiently enter tumor cells with high expression of TGFBR3, especially A549 cells. When the expression of TGFBR3 on the surface of tumor cells (HeLa) was knocked down by RNA interference, the high delivery efficiency of T3BP was correspondingly reduced by 40%, indicating that the delivery was TGFBR3-dependent. Trichosanthin (TCS, a plant-derived ribosome inactivating protein) fused with T3BP can enhance the inhibitory activity of the fusion protein on A549 cells by more than 200 times that of TCS alone. These results indicated that T3BP, as a novel targeting peptide that can efficiently bind TGFBR3 and be used for targeted therapy of tumors with high expression of TGFBR3. This study enriches the supply of tumor-targeting peptides and provides a new potential application option for the treatment of tumors with high expression of TGFBR3.

High-mobility group box-1 impedes skeletal muscle regeneration via downregulation of Pax-7 synthesis by increasing miR-342-5p expression

High mobility group box-1 (HMGB1) is a driver of inflammation in various muscular diseases. In a previous study, we determined that HMGB1 induced the atrophy of skeletal muscle by impairing myogenesis. Skeletal muscle regeneration after injury is dependent on pair box 7 (Pax-7)-mediated myogenic differentiation. In the current study, we determined that the HMGB1-induced downregulation of Pax-7 expression in myoblasts inhibited the regeneration of skeletal muscle. We also determined that HMGB1 inhibits Pax-7 and muscle differentiation by increasing miR-342-5p synthesis via receptors for advanced glycation end-products (RAGE), toll-like receptor (TLR) 2, TLR4, and c-Src signaling pathways. In a mouse model involving glycerol-induced muscle injury, the therapeutic inhibition of HMGB1 was shown to rescue Pax-7 expression and muscle regeneration. The HMGB1/Pax-7 axis is a promising therapeutic target to promote muscular regeneration.

Use of AgomiR and AntagomiR technologies to alter satellite cell proliferation in vitro, miRNA expression, and muscle fiber hypertrophy in intrauterine growth-restricted lambs

Introduction: microRNAs (miRNAs) are small non-coding RNAs that work at the posttranscriptional level to repress gene expression. Several miRNAs are preferentially expressed in skeletal muscle and participate in myogenesis. This research was conducted to alter endogenous miRNA expression in skeletal muscle to promote muscle hypertrophy. Methods: Two experiments were conducted using mimic/agomiR or antagomir technologies to alter miRNA expression and examine changes in myoblast proliferation in vitro (experiment 1) and muscle hypertrophy in vivo (experiment 2). In vitro experiments found that antagomiR-22-3p and mimic-127 increased myoblast proliferation compared to other miRNA treatments or controls. These miRNA treatments, antagomiR-22-3p (ANT22) and agomiR-127 (AGO127), were then used for intramuscular injections in longissimus muscle. Results and discussion: The use of antagomiR or mimic/agomiR treatments down-regulated or up-regulated, respectively, miRNA expression for that miRNA of interest. Expression of predicted target KIF3B mRNA for miR-127 was up-regulated and ACVR2a mRNA was up-regulated for miR-22-3p. ANT22 injection also up-regulated the major regulator of protein synthesis (mTOR). Proteomic analyses identified 11 proteins for AGO127 and 9 proteins for ANT22 that were differentially expressed. Muscle fiber type and cross-sectional area were altered for ANT22 treatments to transition fibers to a more oxidative state. The use of agomiR and antagomir technologies allows us to alter miRNA expression in vitro and in vivo to enhance myoblast proliferation and alter muscle fiber hypertrophy in IUGR lambs during early postnatal growth.

Small RNA sequencing analysis of exosomes derived from umbilical plasma in IUGR lambs

During the summer, pregnant ewes experience heat stress, leading to the occurrence of IUGR lambs. This study aims to explore the biomarkers of exosomal miRNAs derived from umbilical plasma in both IUGR and normal Hu lambs. We establish a heat-stressed Hu sheep model during mid-late gestation and selected IUGR and normal lambs for analysis. Exosomes from umbilical plasma were separated and small RNA sequencing is used to identify differentially expressed miRNAs. Next, we utilize MiRanda to predict the target genes of the differentially expressed miRNAs. To further understand the biological significance of these miRNAs, we conduct GO and KEGG pathway enrichment analysis for their target genes. The study's findings indicate that oar-miR-411a-5p is significantly downregulated in exosomes derived from umbilical plasma of IUGR lambs, while oar-miR-200c is significantly upregulated in the HS-IUGR group (P < 0.05). Furthermore, GO and KEGG enrichment analysis demonstrate that the target genes are involved in the Wnt, TGF-beta, and Rap1 signaling pathways. miRNAs found in exosomes have the potential to be utilized as biomarkers for both the diagnosis and treatment of IUGR fetuses.

MicroRNA-142a-3p regulates neurogenic skeletal muscle atrophy by targeting Mef2a

Peripheral nerve injury can lead to progressive muscle atrophy and poor motor function recovery, which is a difficult point of treatment, and the mechanism needs to be further explored. In previous studies, we found that miR-142a-3p was significantly upregulated and persistently highly expressed in denervated mouse skeletal muscle. Here, we show that overexpression of miR-142a-3p inhibited the growth and differentiation of C2C12 myoblast, while knockdown of miR-142a-3p had a promoting effect. In vitro, knockdown of miR-142a-3p in denervated mouse skeletal muscle effectively increased proliferating muscle satellite cells and ameliorated muscle atrophy. Mechanistically, the myoregulator Mef2a was proved to be an important downstream target of miR-142a-3p, and miR-142a-3p regulates skeletal muscle differentiation and regeneration by inhibiting the expression of Mef2a. The co-knockdown of Mef2a and miR-142a-3p effectively alleviated or offset the biological effects of miR-142a-3p knockdown. In conclusion, our data revealed that miR-142a-3p regulates neurogenic skeletal muscle atrophy by targeting Mef2a.

Transcriptome analysis of mRNAs, lncRNAs, and miRNAs in the skeletal muscle of Tibetan chickens at different developmental stages

Introduction: As a valuable genetic resource, native birds can contribute to the sustainable development of animal production. Tibetan chickens, known for their special flavor, are one of the important local poultry breeds in the Qinghai-Tibet Plateau. However, Tibetan chickens have a slow growth rate and poor carcass traits compared with broilers. Although most of the research on Tibetan chickens focused on their hypoxic adaptation, there were fewer studies related to skeletal muscle development. Methods: Here, we performed the transcriptional sequencing of leg muscles from Tibetan chicken embryos at E (embryonic)10, E14, and E18. Results: In total, 1,600, 4,610, and 2,166 DE (differentially expressed) mRNAs, 210, 573, and 234 DE lncRNAs (long non-coding RNAs), and 52, 137, and 33 DE miRNAs (microRNAs) were detected between E10 and E14, E10 and E18, and E14 and E18, respectively. Functional prediction showed several DE mRNAs and the target mRNAs of DE lncRNAs and DE miRNAs were significantly enriched in sarcomere organization, actin cytoskeleton organization, myofibril, muscle fiber development, and other terms and pathways related to muscle growth and development. Finally, a lncRNA-miRNA-mRNA ceRNA (competing endogenous RNA) network associated with muscle growth and development, which contained 6 DE lncRNAs, 13 DE miRNAs, and 50 DE mRNAs, was constructed based on the screened DE RNAs by Gene Ontology (GO) enrichment. These DE RNAs may play a critical regulatory role in the skeletal muscle development of chickens. Discussion: The results provide a genomic resource for mRNAs, lncRNAs, and miRNAs potentially involved in the skeletal muscle development of chickens, which lay the foundation for further studies of the molecular mechanisms underlying skeletal muscle growth and development in Tibetan chickens.

Characteristics of microRNAs in Skeletal Muscle of Intrauterine Growth-Restricted Pigs

microRNAs are a class of small RNAs that have been extensively studied, which are involved in many biological processes and disease occurrence. The incidence of intrauterine growth restriction is higher in mammals, especially multiparous mammals. In this study, we found that the weight of the longissimus dorsi of intrauterine growth-restricted pigs was significantly lower than that of normal pigs. Then, intrauterine growth-restricted pig longissimus dorsi were used to characterize miRNA expression profiles by RNA sequencing. A total of 333 miRNAs were identified, of which 26 were differentially expressed. Functional enrichment analysis showed that these differentially expressed miRNAs regulate the expression of their target genes (such as PIK3R1, CCND2, AKT3, and MAP3K7), and these target genes play an important role in the proliferation and differentiation of skeletal muscle through signaling pathways such as the PI3K-Akt, MAPK, and FoxO signaling pathways. Furthermore, miRNA-451 was significantly upregulated in IUGR pig skeletal muscle. Overexpression of miR-451 in C2C12 cells significantly promoted the expression of Mb, Myod, Myog, Myh1, and Myh7, suggesting that miR-451 may be involved in the regulation of the myoblastic differentiation of C2C12 cells. Our results reveal the role of miRNA-451 in regulating myogenic differentiation of skeletal muscle in pigs with intrauterine growth restriction.

Targeted Demethylation of the TGFβ1 mRNA Promotes Myoblast Proliferation via Activating the SMAD2 Signaling Pathway

Recent evidence suggested that N6-methyladenosine (m6A) methylation can determine m6A-modified mRNA fate and play an important role in skeletal muscle development. It was well known that transforming growth factor beta 1 (TGFβ1) is involved in a variety of cellular processes, such as proliferation, differentiation, and apoptosis. However, little is known about the m6A-mediated TGFβ1 regulation in myogenesis. Here, we observed an increase in endogenous TGFβ1 expression and activity during myotube differentiation. However, the knockdown of TGFβ1 inhibits the proliferation and induces cell apoptosis of myoblast. Moreover, we found that m6A in 5′-untranslated regions (5′UTR) of TGFβ1 promote its decay and inhibit its expression, leading to the blockage of the TGFβ1/SMAD2 signaling pathway. Furthermore, the targeted specific demethylation of TGFβ1 m6A using dCas13b-FTO significantly increased the TGFβ1-mediated activity of the SMAD2 signaling pathway, promoting myoblast proliferation. These findings suggest that TGFβ1 is an essential regulator of myoblast growth that is negatively regulated by m6A. Overall, these results highlight the critical role of m6A-mediated post-transcriptional regulation in myogenesis.

Spatiotemporal Expression and Functional Analysis of miRNA-22 in the Developing Secondary Palate

OBJECTIVE

Normal development of the embryonic orofacial region requires precise spatiotemporal coordination between numerous genes. MicroRNAs represent small, single-stranded, non-coding molecules that regulate gene expression. This study examines the role of microRNA-22 (miR-22) in murine orofacial ontogeny.

METHODS

Spatiotemporal and differential expression of miR-22 (mmu-miR-22-3p) within the developing secondary palate was determined by in situ hybridization and quantitative real-time PCR, respectively. Bioinformatic approaches were used to predict potential mRNA targets of miR-22 and analyze their association with cellular functions indispensable for normal orofacial ontogeny. An in vitro palate organ culture system was used to assess the role of miR-22 in secondary palate development.

RESULTS

There was a progressive increase in miR-22 expression from GD12.5 to GD14.5 in palatal processes. On GD12.5 and GD13.5, miR-22 was expressed in the future oral, nasal, and medial edge epithelia. On GD14.5, miR-22 expression was observed in the residual midline epithelial seam (MES), the nasal epithelium and the mesenchyme, but not in the oral epithelium. Inhibition of miR-22 activity in palate organ cultures resulted in failure of MES removal. Bioinformatic analyses revealed potential mRNA targets of miR-22 that may play significant roles in regulating apoptosis, migration, and/or convergence/extrusion, developmental processes that modulate MES removal during palatogenesis.

CONCLUSIONS

Results from the current study suggest a key role for miR-22 in the removal of the MES during palatogenesis and that miR-22 may represent a potential contributor to the etiology of cleft palate.

A pathway analysis-based algorithm for calculating the participation degree of ncRNA in transcriptome

After sequencing, it is common to screen ncRNA according to expression differences. But this may lose a lot of valuable information and there is currently no indicator to characterize the regulatory function and participation degree of ncRNA on transcriptome. Based on existing pathway enrichment methods, we developed a new algorithm to calculating the participation degree of ncRNA in transcriptome (PDNT). Here we analyzed multiple data sets, and differentially expressed genes (DEGs) were used for pathway enrichment analysis. The PDNT algorithm was used to calculate the Contribution value (C value) of each ncRNA based on its target genes and the pathways they participates in. The results showed that compared with ncRNAs screened by log2 fold change (FC) and p-value, those screened by C value regulated more DEGs in IPA canonical pathways, and their target DEGs were more concentrated in the core region of the protein-protein interaction (PPI) network. The ranking of disease critical ncRNAs increased integrally after sorting with C value. Collectively, we found that the PDNT algorithm provides a measure from another view compared with the log2FC and p-value and it may provide more clues to effectively evaluate ncRNA.

Milk-Derived miR-22-3p Promotes Proliferation of Human Intestinal Epithelial Cells (HIECs) by Regulating Gene Expression

MicroRNA (miRNA) is small non-coding RNA involved in gene silencing and post-transcriptional regulation of gene expression. Milk exosomes are microvesicles containing microRNAs (miRNAs). miR-22-3p (miR-22) is plentiful in human milk exosomes and may contribute to intestinal development since milk exosomes and microRNAs are resistant to gastrointestinal digestion in infants. After miR-22 mimics were transfected to human intestinal crypt-like epithelial cells (HIECs) using Lipofectamine for 24 h, RNA was isolated for microarray assay. Microarray results show that miR-22 markedly regulates gene expression, and the roles of miR-22 include promotion of proliferation, regulation of immune functions, and inhibition of apoptosis. Based on the microarray results and miR-22 predicted target genes, CCAAT/enhancer-binding protein δ (C/EBPδ) may be an important direct target of miR-22. C/EBPδ is a transcription factor that regulates numerous biological processes including cell proliferation. In miR-22 transfected HIECs, expression of the C/EBPδ gene was significantly inhibited. Silencing of the C/EBPδ gene by siRNA resulted in increased proliferation of HIECs. A luciferase assay showed that miR-22 specifically binds to the 3'-untranslated region of C/EBPδ mRNA. In summary, milk-derived miR-22 promotes intestinal proliferation by modifying gene expression, and C/EBPδ may be an important target for miR-22 involved in this effect.

Modulating myoblast differentiation with RNA-based controllers

Tunable genetic controllers play a critical role in the engineering of biological systems that respond to environmental and cellular signals. RNA devices, a class of engineered RNA-based controllers, enable tunable gene expression control of target genes in response to molecular effectors. RNA devices have been demonstrated in a number of systems showing proof-of-concept of applying ligand-responsive control over therapeutic activities, including regulation of cell fate decisions such as T cell proliferation and apoptosis. Here, we describe the application of a theophylline-responsive RNA device in a muscle progenitor cell system to control myogenic differentiation. Ribozyme-based RNA switches responsive to theophylline control fluorescent reporter expression in C2C12 myoblasts in a ligand dependent manner. HRAS and JAK1, both anti-differentiation proteins, were incorporated into RNA devices. Finally, we demonstrate that the regulation of HRAS expression via theophylline-responsive RNA devices results in the modulation of myoblast differentiation in a theophylline-dependent manner. Our work highlights the potential for RNA devices to exert drug-responsive, tunable control over cell fate decisions with applications in stem cell therapy and basic stem cell biology research.

A Specific microRNA Targets an Elongase of Very Long Chain Fatty Acids to Regulate Fatty Acid Composition and Mitochondrial Morphology of Skeletal Muscle Cells

Recently, miR-22 has been suggested to be an important microRNA (miRNA) affecting meat quality. Studies have shown that muscle fatty acid composition and mitochondrial function are closely related to meat quality. The regulatory mechanism of miR-22 on skeletal muscle fatty acid composition and mitochondrial function is not well characterized. Therefore, we aimed to explore the effects of miR-22 on fatty acid composition and mitochondrial function in C2C12 cells. Here, it demonstrate that elevated expression of miR-22 significantly repressed fatty acid elongation and mitochondrial morphology in C2C12 myoblasts, while the knockdown of miR-22 showed opposite results. Furthermore, miR-22 targets the elongase of very long chain fatty acids 6 (ELOVL6) and represses its expression in muscle cells. Knockdown of ELOVL6 mimicked the effect of miR-22 on fatty acid composition and mitochondrial function, while overexpression of ELOVL6 restored the effects of miR-22. These findings indicate that miR-22 downregulates the elongation of fatty acids and mitochondrial morphology by inhibiting ELOVL6 expression in muscle cells, which may provide some useful information for controlling muscle lipid accumulation and mitochondrial function in livestock in the future.

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.

Green Synthesis of Silymarin-Chitosan Nanoparticles as a New Nano Formulation with Enhanced Anti-Fibrotic Effects against Liver Fibrosis

Background: Silymarin (SIL) has long been utilized to treat a variety of liver illnesses, but due to its poor water solubility and low membrane permeability, it has a low oral bioavailability, limiting its therapeutic potential. Aim: Design and evaluate hepatic-targeted delivery of safe biocompatible formulated SIL-loaded chitosan nanoparticles (SCNPs) to enhance SIL’s anti-fibrotic effectiveness in rats with CCl₄-induced liver fibrosis. Methods: The SCNPs and chitosan nanoparticles (CNPs) were prepared by ionotropic gelation technique and are characterized by physicochemical parameters such as particle size, morphology, zeta potential, and in vitro release studies. The therapeutic efficacy of successfully formulated SCNPs and CNPs were subjected to in vivo evaluation studies. Rats were daily administered SIL, SCNPs, and CNPs orally for 30 days. Results: The in vivo study revealed that the synthesized SCNPs demonstrated a significant antifibrotic therapeutic action against CCl₄-induced hepatic injury in rats when compared to treated groups of SIL and CNPs. SCNP-treated rats had a healthy body weight, with normal values for liver weight and liver index, as well as significant improvements in liver functions, inflammatory indicators, antioxidant pathway activation, and lipid peroxidation reduction. The antifibrotic activities of SCNPs were mediated by suppressing the expression of the main fibrosis mediators TGFβR1, COL3A1, and TGFβR2 by boosting the hepatic expression of protective miRNAs; miR-22, miR-29c, and miR-219a, respectively. The anti-fibrotic effects of SCNPs were supported by histopathology and immunohistochemistry (IHC) study. Conclusions: According to the above results, SCNPs might be the best suitable carrier to target liver cells in the treatment of liver fibrosis.

Phosphoglycerate dehydrogenase positively regulates the proliferation of chicken muscle cells

Phosphoglycerate dehydrogenase (PHGDH) is the rate-limiting enzyme in the serine synthesis pathway. However, the regulatory role of PHGDH in muscle development is unclear. We report that the expression of PHGDH increased significantly during proliferation of chicken skeletal muscle satellite cells. Knockdown of PHGDH by an siRNA suppressed myoblast proliferation, whereas overexpression of PHGDH enhanced muscle cell proliferation. Furthermore, PHGDH promoted the expression of Forkhead box protein M1 (FoxM1). Knockdown of FoxM1 by an siRNA attenuated the proliferation of chicken muscle cells, whereas its overexpression significantly promoted proliferation. Additionally, siRNA-PHGDH inhibited pcDNA3.1-FoxM1-induced FoxM1 expression in chicken muscle cells. Moreover, PHGDH inhibition overcame the stimulation by pcDNA3.1-FoxM1 of cell cycle-related gene expression. We propose that PHGDH accelerates chicken muscle cell proliferation by increasing FoxM1 expression.

MiR-22-3p Inhibits Proliferation and Promotes Differentiation of Skeletal Muscle Cells by Targeting IGFBP3 in Hu Sheep

The growth and development of skeletal muscle require a series of regulatory factors. MiRNA is a non-coding RNA with a length of about 22 nt, which can inhibit the expression of mRNA and plays an important role in the growth and development of muscle cells. The role of miR-22-3p in C2C12 cells and porcine skeletal muscle has been reported, but it has not been verified in Hu sheep skeletal muscle. Through qPCR, CCK-8, EdU and cell cycle studies, we found that overexpression of miR-22-3p inhibited proliferation of skeletal muscle cells (p < 0.01). The results of qPCR and immunofluorescence showed that overexpression of miR-22-3p promoted differentiation of skeletal muscle cells (p < 0.01), while the results of inhibiting the expression of miR-22-3p were the opposite. These results suggested that miR-22-3p functions in growth and development of sheep skeletal muscle cells. Bioinformatic analysis with mirDIP, miRTargets, and RNAhybrid software suggested IGFBP3 was the target of miR-22-3p, which was confirmed by dual-luciferase reporter system assay. IGFBP3 is highly expressed in sheep skeletal muscle cells. Overexpression of IGFBP3 was found to promote proliferation of skeletal muscle cells indicated by qPCR, CCK-8, EdU, and cell cycle studies (p < 0.01). The results of qPCR and immunofluorescence experiments proved that overexpression of IGFBP3 inhibited differentiation of skeletal muscle cells (p < 0.01), while the results of interfering IGFBP3 with siRNA were the opposite. These results indicate that miR-22-3p is involved in proliferation and differentiation of skeletal muscle cells by targeting IGFBP3.

Differential microRNA profiles of intramuscular and secreted extracellular vesicles in human tissue-engineered muscle

Exercise affects the expression of microRNAs (miR/s) and muscle-derived extracellular vesicles (EVs). To evaluate sarcoplasmic and secreted miR expression in human skeletal muscle in response to exercise-mimetic contractile activity, we utilized a three-dimensional tissue-engineered model of human skeletal muscle ("myobundles"). Myobundles were subjected to three culture conditions: no electrical stimulation (CTL), chronic low frequency stimulation (CLFS), or intermittent high frequency stimulation (IHFS) for 7 days. RNA was isolated from myobundles and from extracellular vesicles (EVs) secreted by myobundles into culture media; miR abundance was analyzed by miRNA-sequencing. We used edgeR and a within-sample design to evaluate differential miR expression and Pearson correlation to evaluate correlations between myobundle and EV populations within treatments with statistical significance set at p < 0.05. Numerous miRs were differentially expressed between myobundles and EVs; 116 miRs were differentially expressed within CTL, 3 within CLFS, and 2 within IHFS. Additionally, 25 miRs were significantly correlated (18 in CTL, 5 in CLFS, 2 in IHFS) between myobundles and EVs. Electrical stimulation resulted in differential expression of 8 miRs in myobundles and only 1 miR in EVs. Several KEGG pathways, known to play a role in regulation of skeletal muscle, were enriched, with differentially overrepresented miRs between myobundle and EV populations identified using miEAA. Together, these results demonstrate that in vitro exercise-mimetic contractile activity of human engineered muscle affects both their expression of miRs and number of secreted EVs. These results also identify novel miRs of interest for future studies of the role of exercise in organ-organ interactions in vivo.

Preparation and Characterization of Silymarin-Conjugated Gold Nanoparticles with Enhanced Anti-Fibrotic Therapeutic Effects against Hepatic Fibrosis in Rats: Role of MicroRNAs as Molecular Targets

BACKGROUND

The main obstacles of silymarin (SIL) application in liver diseases are its low bioavailability, elevated metabolism, rapid excretion in bile and urine, and inefficient intestinal resorption. The study aimed to synthesize and characterize silymarin-conjugated gold nanoparticles (SGNPs) formulation to improve SIL bioavailability and release for potentiating its antifibrotic action.

METHODS

Both SGNPs and gold nanoparticles (GNPs) were prepared and characterized using standard characterization techniques. The improved formulation was assessed for in vitro drug release study and in vivo study on rats using CCl₄ induced hepatic fibrosis model. SIL, SGNPs, and GNPs were administered by oral gavage daily for 30 days. At the end of the study, rats underwent anesthesia and were sacrificed, serum samples were collected for biochemical analysis. Liver tissues were collected to measure the genes and microRNAs (miRNAs) expressions. Also, histopathological and immunohistochemistry (IHC) examinations of hepatic tissues supported these results.

RESULTS

The successful formation and conjugation of SGNPs were confirmed by measurements methods. The synthesized nanohybrid SGNPs showed significant antifibrotic therapeutic action against CCl₄-induced hepatic damage in rats, and preserved normal body weight, liver weight, liver index values, retained normal hepatic functions, lowered inflammatory markers, declined lipid peroxidation, and activated the antioxidant pathway nuclear factor erythroid-2-related factor 2 (NRF2). The antifibrotic activities of SGNPs mediated through enhancing the hepatic expression of the protective miRNAs; miR-22, miR-29c, and miR-219a which results in suppressed expression of the main fibrosis mediators; TGFβR1, COL3A1, and TGFβR2, respectively. The histopathology and IHC analysis confirmed the anti-fibrotic effects of SGNPs.

CONCLUSIONS

The successful synthesis of SGNPs with sizes ranging from 16 up to 20 nm and entrapment efficiency and loading capacity 96% and 38.69%, respectively. In vivo studies revealed that the obtained nano-formulation of SIL boosted its anti-fibrotic effects.

The Essential Role of Stathmin in Myoblast C2C12 for Vertical Vibration-Induced Myotube Formation

Vertical vibration (VV) is a type of whole body vibration, which induces muscle contraction through vibration to improve muscle strength and bone density. However, the mechanism of VV on muscle cell myotube formation is still unclear. In the current study, we aim to clarify the mechanism involved in VV’s stimulation of myotube formation. In order to identify the molecules regulated by VV, we performed proteomics analysis including 2D electrophoresis combined with MALDI-TOF/TOF Mass. Stathmin was identified as a high potential molecule responding to VV stimulation, and we found that under VV stimulation, the expression of stathmin gene and protein increased in a time-dependent manner. In addition, we also confirmed that the increase of stathmin stimulated by VV is mediated through the PI3K/Akt pathway. Furthermore, stathmin siRNA significantly down-regulated the expression of myogenic regulatory factor (MRF) MyoD, decorin, and type I collagen (Col-I), and down-regulated the cellular process regulators such as FGF7, TGFBr1 and PAK3. Taken together, our results confirm that under the stimulation of VV, PI3K/Akt and stathmin would be activated, as well as the up-regulation of MRFs, such as FGF7, TGFBr1 and PAK3 to initiate myogenesis. It also showed that the response of MRF to VV stimulation was significantly related to stathmin expression, which also confirmed the importance of stathmin in the entire myotube formation process. This study may provide evidence of stathmin as a biological indicator of VV to increase muscle strength.

Lipoxin A4 methyl ester protects PC12 cells from ketamine-induced neurotoxicity via the miR-22/BAG5 pathway

OBJECTIVE

Ketamine is an anesthetic that induces neurotoxicity when administered at high doses. In this work, we explored the protective effects of lipoxin A₄ methyl ester (LXA₄ ME) against ketamine-induced neurotoxicity and the underlying protective mechanism in pheochromocytoma (PC12) cells.

METHODS

PC12 cells were treated with 50 μM of ketamine and different LXA₄ ME concentrations of LXA4 ME (5-50 nM) for 24 h, and their viability, apoptosis, and oxidative status were assessed.

RESULTS

Quantitative real-time polymerase chain reaction experiments showed that ketamine downregulated miR-22 expression and upregulated Bcl-2-associated athanogene 5 (BAG5) in PC12 cells in a concentration-dependent manner. LXA₄ ME induced the opposite effects, thus attenuating ketamine-induced neurotoxicity. Further in vitro assays showed that miR-22 directly targeted BAG5, thus promoting cell viability by suppressing cell apoptosis and oxidative stress. Under expression miR-22 or upregulation of BAG5 antagonized the effects of LXA₄ ME.

CONCLUSION

LXA₄ ME can protect PC12 cells from ketamine-induced neurotoxicity by activating the miR-22/BAG5 signaling pathway. Thus, LXA₄ ME can be used as a protective drug against ketamine-induced neural damage.

Circular RNA hsa_circ_0026552 inhibits the proliferation, migration and invasion of trophoblast cells via the miR‑331‑3p/TGF‑βR1 axis in pre‑eclampsia

Globally, pre-eclampsia (PE) is a gestational disorder that causes increased morbidity of the fetus and mortality induced by pregnancy. Despite various studies, the understanding of the causes or mechanism of the development of PE remains elusive. Thus, the present study aimed to investigate the role of circular (circ)RNA hsa_circ_0026552 (hsa_circ_0026552) in the development of PE and its mechanism of regulation. hsa_circ_0026552 differential expression in PE tissue data and clinical samples were analyzed and it was observed that hsa_circ_0026552 is highly upregulated in PE samples. Furthermore, miR-331-3p was detected as an hsa_circ_0026552 target miRNA and TGF-βR1 gene as a target of miR-331-3p. These results were confirmed using various assays, including dual-luciferase reporter, reverse transcription-quantitative PCR and RNA pull-down assay. It was observed that miR-331-3p expression was negatively correlated to hsa_circ_0026552 relative expression, while TGF-βR1 expression was positively correlated to hsa_circ_0026552 expression evaluated by Pearson's correlation test. The functional experiments, including Cell Counting Kit-8, colony formation and Transwell assay, showed that silencing hsa_circ_0026552 could significantly strengthen the proliferation, migration and invasion of the trophoblastic HTR-8/SVneo cells, but the subsequent overexpression of hsa_circ_0026552 reversed this. Mechanistically, it was concluded that hsa_circ_0026552 acts as a miR-331-3p sponge to upregulate TGF-βR1 expression in trophoblasts and is involved significantly in PE development and progression in pregnant women. The circRNA hsa_circ_0026552 could be a novel therapeutic target and prognostic biomarker for PE.

Downregulation of Tim-1 inhibits the proliferation, migration and invasion of glioblastoma cells via the miR-133a/TGFBR1 axis and the restriction of Wnt/β-catenin pathway

Background

Glioblastoma remains one of the most lethal brain cancers. T-cell immunoglobulin and mucin domain 1 (Tim-1) is associated with various immune diseases. The molecular mechanism of Tim-1 in regulating glioblastoma cell proliferation, invasion, and migration is still unknown. Moreover, it has shown that miR-133a plays an important role in glioblastoma. However, little is known about the interaction between Tim-1 and miR-133a in glioblastoma.

Methods

Tim-1 expression in glioblastoma and normal brain tissues was detected by qPCR, Western Blot and IHC. After Tim-1 knockdown in U251 and U87 cells, genes showing significantly differential expression, along with the significant differential miRNAs were analyzed using RNA-seq analysis. The binding sites were verified using dual-luciferase reporter gene assay. U251 and U87 cells were allocated into the small harpin-negative control (sh-NC), sh-Tim-1, sh-Tim-1 + inhibitor NC, and sh-Tim-1 + miR-133a inhibitor group. Cell proliferation, migration, and invasion were determined by CCK-8, flow cytometry, wound-healing and Transwell assays, respectively. Next, U251 and U87 cells were allocated into the mimic NC, miR-133a mimic, miR-133a mimic + pcDNA3.1, and miR-133a mimic + pcDNA3.1-TGFBR1 groups, followed by the detection of cell proliferation, migration, and invasion. Western blot was used to identify the expression of vital kinases in the Wnt/β-catenin pathway.

Results

Tim-1 was highly expressed in glioblastoma tissues compared with that in normal brain tissues. RNA-seq analysis showed that Tim-1 knockdown could lead to the downregulation of TGFBR1 and the upregulation of miR-133a. The binding sites between TGFBR1 and miR-133a were confirmed. Tim-1 knockdown impaired the invasion, migration, proliferation of U251 and U87 cells, which could be reversed by miR-133a downregulation. miR-133a upregulation inhibited the proliferation, invasion, and migration of U251 and U87 cells, which could be reversed by TGFBR1 upregulation. Tim-1 knockdown and miR-133a upregulation could inhibit the activation of the Wnt/β-catenin pathway, while the elevation of TGFBR1 showed opposite effects.

Conclusion

Tim-1 knockdown inhibited glioblastoma cell proliferation, invasion, and migration through the miR-133a/TGFBR1 axis and restrained the activation of the Wnt/β-catenin pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02036-1.

CircMAPK1 promotes the proliferation and migration of vascular smooth muscle cells through miR-22-3p/ methyl-CpG binding protein 2 axis

BACKGROUND AND AIMS

Atherosclerosis is a chronic inflammatory disease. The proliferation and migration of vascular smooth muscle cells (VSMCs) contribute to intimal hyperplasia. CircRNAs are class of endogenous RNA and implicated in the various biological processes. However, the role of circRNAs in atherosclerosis remains largely unknown.

METHODS AND RESULTS

Mice models of atherosclerosis were established using APOE-/- mice fed with high-fat diet. High-throughput sequencing was performed to profile the expression of circRNAs in atherosclerosis. A total of 1289 circRNAs were identified. Six circRNAs were up-regulated and 12 circRNAs were down-regulated in the atherosclerotic plaque tissues. Then we focused on circMAPK1, which showed a high level in atherosclerosis. Silencing circMAPK1 suppressed the proliferation and migration of VSMCs. Further study showed that circMAPK1 bound with miR-22-3p. CircMAPK1 silencing increased the level of miR-22-3p and suppressed the level of MECP2, a known target of miR-22-3p. Interestingly, suppression of miR-22-3p rescued the effect of circMAPK1 silencing on the proliferation and migration of VSMCs.

CONCLUSION

CircMPAK1 promoted the proliferation and migration of VSMCs through miR-22-3p/MECP2 axis. Our study revealed the role of circMAPK1 in atherosclerosis and shed lights on the treatment of atherosclerosis.

Long noncoding RNA-SNHG20 promotes silica-induced pulmonary fibrosis by miR-490-3p/TGFBR1 axis

Silicosis is a universal occupational disease, which is caused by long-term crystalline silica exposure. Recent studies have shown that noncoding RNAs participate in diverse pathological cellular pathways. However, the precise regulation mechanism remains limited in silicosis. Here, we established a silica-induced mouse fibrosis model (all mice received a one-time intratracheal instillation with 50 mg/kg of silica in 0.05 mL sterile saline). MiR-490-3p was significantly downregulated in silica-induced fibrotic mouse lung tissues and TGF-β1 treated fibroblasts. Moreover, overexpressed miR-490-3p could relieve silica-induced lung fibrosis in vivo, and prevent the process of fibroblast-to-myofibroblast transition(FMT)in vitro. Mechanistically, TGFBR1 was one of the major target genes of miR-490-3p, and tightly associated with the process of fibroblasts activation. SNHG20, as opposed to miR-490-3p expression, was elevated in TGF-β1-treated fibroblast cell lines and contributed to decreased levels of miR-490-3p. Taken together, these data indicated that miR-490-3p plays a key role in silica-induced pulmonary fibrosis. Our results suggested that SNHG20/miR-490-3p/TGFBR1 axis may provide a new treatment target of pulmonary fibrosis.

Piperlongumine inhibits the growth of non-small cell lung cancer cells via the miR-34b-3p/TGFBR1 pathway

BACKGROUND

Non-small cell lung cancer is a common type of lung cancer. Piperlongumine (PL), which is extracted from the roots of piperaceae plant, long pepper, and peppercorn, is an alkaloid amide that inhibits tumor growth and metastasis. However, whether it affects lung cancer cells remains unclear.

METHODS

We assessed the effects of PL on the proliferation and apoptosis of A549 and H1299 NSCLC cell lines.

RESULTS

PL was mildly toxic to normal human bronchial epithelial cells and significantly suppressed growth and facilitated apoptosis of A549 and H1299 cells. It also upregulated microRNA (miR)-34b-3p and downregulated the transforming growth factor beta type I receptor (TGFBR1). The dual-luciferase reporter assay showed that TGFBR1 is a target gene of miR-34b-3p. Silencing of miR-34b-3p or overexpression of TGFBR1 partially attenuated the effects of PL on A549 and H1299 cells.

CONCLUSIONS

PL inhibits proliferation and induces apoptosis of A549 and H1299 cells by upregulating miR-34b-3p and modulating TGFBR1 signaling pathway.

Tiny Regulators of Massive Tissue: MicroRNAs in Skeletal Muscle Development, Myopathies, and Cancer Cachexia

Skeletal muscles are the largest tissues in our body and the physiological function of muscle is essential to every aspect of life. The regulation of development, homeostasis, and metabolism is critical for the proper functioning of skeletal muscle. Consequently, understanding the processes involved in the regulation of myogenesis is of great interest. Non-coding RNAs especially microRNAs (miRNAs) are important regulators of gene expression and function. MiRNAs are small (~22 nucleotides long) noncoding RNAs known to negatively regulate target gene expression post-transcriptionally and are abundantly expressed in skeletal muscle. Gain- and loss-of function studies have revealed important roles of this class of small molecules in muscle biology and disease. In this review, we summarize the latest research that explores the role of miRNAs in skeletal muscle development, gene expression, and function as well as in muscle disorders like sarcopenia and Duchenne muscular dystrophy (DMD). Continuing with the theme of the current review series, we also briefly discuss the role of miRNAs in cancer cachexia.

Isolation and identification of goose skeletal muscle satellite cells and preliminary study on the function of C1q and tumor necrosis factor-related protein 3 gene

Objective

Skeletal muscle satellite cells (SMSCs) are significant for the growth, regeneration, and maintenance of skeletal muscle after birth. However, currently, few studies have been performed on the isolation, culture and inducing differentiation of goose muscle satellite cells. Previous studies have shown that C1q and tumor necrosis factor-related protein 3 (CTRP3) participated in the process of muscle growth and development, but its role in the goose skeletal muscle development is not yet clear. This study aimed to isolate, culture, and identify the goose SMSCs in vitro. Additionally, to explore the function of CTRP3 in goose SMSCs.

Methods

Goose SMSCs were isolated using 0.25% trypsin from leg muscle (LM) of 15 to 20 day fertilized goose eggs. Cell differentiation was induced by transferring the cells to differentiation medium with 2% horse serum and 1% penicillin streptomycin. Immunofluorescence staining of Desmin and Pax7 was used to identify goose SMSCs. Quantitative realtime polymerase chain reaction and western blot were applied to explore developmental expression profile of CTRP3 in LM and the regulation of CTRP3 on myosin heavy chains (MyHC), myogenin (MyoG) expression and Notch signaling pathway related genes expression.

Results

The goose SMSCs were successfully isolated and cultured. The expression of Pax7 and Desmin were observed in the isolated cells. The expression of CTRP3 decreased significantly during leg muscle development. Overexpression of CTRP3 could enhance the expression of two myogenic differentiation marker genes, MyHC and MyoG. But knockdown of CTRP3 suppressed their expression. Furthermore, CTRP3 could repress the mRNA level of Notch signaling pathway-related genes, notch receptor 1, notch receptor 2 and hairy/enhancer-of-split related with YRPW motif 1, which previously showed a negative regulation in myoblast differentiation.

Conclusion

These findings provide a useful cell model for the future research on goose muscle development and suggest that CTRP3 may play an essential role in skeletal muscle growth of goose.

miR-324-5p Inhibits C2C12 cell Differentiation and Promotes Intramuscular Lipid Deposition through lncDUM and PM20D1

Skeletal muscle is an important metabolic organ of the body, and impaired skeletal muscle differentiation can result in a wide range of metabolic diseases. It has been shown that microRNAs (miRNAs) play an important role in skeletal muscle differentiation. The aim of this study was to investigate the role of mmu-miR-324-5p in the differentiation of C2C12 myoblasts and lipid droplet deposition in myotubes for future targeted therapies. We found that mmu-miR-324-5p was highly expressed in mouse skeletal muscle. Overexpression of miR-324-5p significantly inhibited C2C12 myoblast differentiation while promoting oleate-induced lipid accumulation and β-oxidation in C2C12 myoblasts. Conversely, inhibition of mmu-miR-324-5p promoted C2C12 myoblast differentiation and inhibited lipid deposition in myotubes. Mechanistically, mmu-miR-324-5p negatively regulated the expression of long non-coding Dum (lncDum) and peptidase M20 domain containing 1 (Pm20d1) in C2C12 myoblasts. Reduced lncDum expression was associated with a significant decrease in the expression of myogenesis-related genes. Knockdown of mmu-miR-324-5p increased the levels of lncDum and myogenesis-related gene expression. Following oleate-induced lipid deposition in C2C12 myoblasts, overexpression of mmu-miR-324-5p decreased the expression of Pm20d1 while increasing the expression of mitochondrial β-oxidation and long-chain fatty acid synthesis-related genes. In conclusion, we provide evidence that miR-324-5p inhibits C2C12 myoblast differentiation and promotes intramuscular lipid deposition by targeting lncDum and Pm20d1, respectively.

A potential therapeutic effect of catalpol in Duchenne muscular dystrophy revealed by binding with TAK1

BACKGROUND

Duchenne muscular dystrophy (DMD) is a progressive muscle disease caused by the loss of dystrophin, which results in inflammation, fibrosis, and the inhibition of myoblast differentiation in skeletal muscle. Catalpol, an iridoid glycoside, improves skeletal muscle function by enhancing myogenesis; it has potential to treat DMD. We demonstrate the positive effects of catalpol in dystrophic skeletal muscle.

METHODS

mdx (loss of dystrophin) mice (n = 18 per group) were treated with catalpol (200 mg/kg) for six consecutive weeks. Serum analysis, skeletal muscle performance and histology, muscle contractile function, and gene and protein expression were performed. Molecular docking and ligand-target interactions, RNA interference, immunofluorescence, and plasmids transfection were utilized to explore the protective mechanism in DMD by which catalpol binding with transforming growth factor-β-activated kinase 1 (TAK1) in skeletal muscle.

RESULTS

Six weeks of catalpol treatment improved whole-body muscle health in mdx mice, which was characterized by reduced plasma creatine kinase (n = 18, -35.1%, P < 0.05) and lactic dehydrogenase (n = 18, -10.3%, P < 0.05) activity. These effects were accompanied by enhanced grip strength (n = 18, +25.4%, P < 0.05) and reduced fibrosis (n = 18, -29.0% for hydroxyproline content, P < 0.05). Moreover, catalpol treatment protected against muscle fatigue and promoted muscle recovery in the tibialis anterior (TA) and diaphragm (DIA) muscles (n = 6, +69.8%, P < 0.05 and + 74.8%, P < 0.001, respectively), which was accompanied by enhanced differentiation in primary myoblasts from DMD patients (n = 6, male, mean age: 4.7 ± 1.9 years) and mdx mice. In addition, catalpol eliminated p-TAK1 overexpression in mdx mice (n = 12, -21.3%, P < 0.05) and primary myoblasts. The catalpol-induced reduction in fibrosis and increased myoblast differentiation resulted from the inhibition of TAK1 phosphorylation, leading to reduced myoblast trans-differentiation into myofibroblasts. Catalpol inhibited the phosphorylation of TAK1 by binding to TAK1, possibly at Asp-206, Thr-208, Asn-211, Glu-297, Lys-294, and Tyr-293.

CONCLUSIONS

Our findings show that catalpol and TAK1 inhibitors substantially improve whole-body muscle health and the function of dystrophic skeletal muscles and may provide a novel therapy for DMD.

Analysis of dynamic and widespread lncRNA and miRNA expression in fetal sheep skeletal muscle

The sheep is an economically important animal, and there is currently a major focus on improving its meat quality through breeding. There are variations in the growth regulation mechanisms of different sheep breeds, making fundamental research on skeletal muscle growth essential in understanding the regulation of (thus far) unknown genes. Skeletal muscle development is a complex biological process regulated by numerous genes and non-coding RNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). In this study, we used deep sequencing data from sheep longissimus dorsi (LD) muscles sampled at day 60, 90, and 120 of gestation, as well as at day 0 and 360 following birth, to identify and examine the lncRNA and miRNA temporal expression profiles that regulate sheep skeletal myogenesis. We stained LD muscles using histological sections to analyse the area and circumference of muscle fibers from the embryonic to postnatal development stages. Our results showed that embryonic skeletal muscle growth can be characterized by time. We obtained a total of 694 different lncRNAs and compared the differential expression between the E60 vs. E90, E90 vs. E120, E120 vs. D0, and D0 vs. D360 lncRNA and gene samples. Of the total 701 known sheep miRNAs we detected, the following showed a wide range of expression during the embryonic stage: miR-2387, miR-105, miR-767, miR-432, and miR-433. We propose that the detected lncRNA expression was time-specific during the gestational and postnatal stages. GO and KEGG analyses of the genes targeted by different miRNAs and lncRNAs revealed that these significantly enriched processes and pathways were consistent with skeletal muscle development over time across all sampled stages. We found four visual lncRNA–gene regulatory networks that can be used to explore the function of lncRNAs in sheep and may be valuable in helping improve muscle growth. This study also describes the function of several lncRNAs that interact with miRNAs to regulate myogenic differentiation.

Long Non-coding RNAs Are Differentially Expressed After Different Exercise Training Programs

Background

Molecular regulation related to the health benefits of different exercise modes remains unclear. Long non-coding RNAs (lncRNAs) have emerged as an RNA class with regulatory functions in health and diseases. Here, we analyzed the expression of lncRNAs after different exercise training programs and their possible modes of action related to physical exercise adaptations.

Methods

Public high-throughput RNA-seq data (skeletal muscle biopsies) were downloaded, and bioinformatics analysis was performed. We primarily analyzed data reports of 12 weeks of resistance training (RT), high-intensity interval training (HIIT), and combined (CT) exercise training. In addition, we analyzed data from 8 weeks of endurance training (ET). Differential expression analysis of lncRNAs was performed, and an adjusted P-value < 0.1 and log2 (fold change) ≥0.5 or ≤-0.5 were set as the cutoff values to identify differentially expressed lncRNAs (DELs).

Results

We identified 204 DELs after 12 weeks of HIIT, 43 DELs after RT, and 15 DELs after CT. Moreover, 52 lncRNAs were differentially expressed after 8 weeks of ET. The lncRNA expression pattern after physical exercise was very specific, with distinct expression profiles for the different training programs, where few lncRNAs were common among the exercise types. LncRNAs may regulate molecular responses to exercise, such as collagen fibril organization, extracellular matrix organization, myoblast and plasma membrane fusion, skeletal muscle contraction, synaptic transmission, PI3K and TORC regulation, autophagy, and angiogenesis.

Conclusion

For the first time, we show that lncRNAs are differentially expressed in skeletal muscle after different physical exercise programs, and these lncRNAs may act in various biological processes related to physical activity adaptations.

miR-22-3p regulates muscle fiber-type conversion through inhibiting AMPK/SIRT1/PGC-1α pathway

MicroRNAs (miRNAs) are a class of conserved non-coding RNAs that are widely regarded as important regulators in a variety of biological processes. Increasing evidence has revealed that skeletal muscle fiber-type conversion is regulated by miRNAs, but the molecular mechanism is still not fully understood. In this study, we confirmed the role of miR-22-3p on skeletal muscle fiber-type conversion and investigated its potential mechanism in C2C12 myotubes. Here, we found that the miR-22-3p mimics inhibited the expressions of myosin heavy chain I (MyHC I), MyHC IIa and promoted the expression of MyHC IIb, while miR-22-3p inhibitor got inverse results. miR-22-3p mimics also downregulated phosphorylated AMPK, SIRT1 and PGC-1ɑ protein levels, which control the expression of oxidative fiber-related genes. Furthermore, Compound C (AMPK inhibitor) eliminated the effect of miR-22-3p inhibitor on MyHC I, MyHC IIa and MyHC IIb expressions. However, AICAR (AMPK activator) also abolished the effect of miR-22-3p mimics on MyHC I, MyHC IIa and MyHC IIb expressions. Collectively, our results suggest that miR-22-3p regulates skeletal muscle fiber-type conversion through inhibiting AMPK/SIRT1/PGC-1ɑ signaling pathway.

Long Noncoding RNA SOX2-OT Exacerbates Hypoxia-Induced Cardiomyocytes Injury by Regulating miR-27a-3p/TGFβR1 Axis

Background

Myocardial infarction (MI) was a severe cardiovascular disease resulted from acute, persistent hypoxia, or ischemia condition. Additionally, MI generally led to heart failure, even sudden death. A multitude of research studies proposed that long noncoding RNAs (lncRNAs) frequently participated in the regulation of heart diseases. The specific function and molecular mechanism of SOX2-OT in MI remained unclear. Aim of the Study. The current research was aimed to explore the role of SOX2-OT in MI.

Methods

Bioinformatics analysis (DIANA tools and Targetscan) and a wide range of experiments (CCK-8, flow cytometry, RT-qPCR, luciferase reporter, RIP, caspase-3 activity, trans-well, and western blot assays) were adopted to investigate the function and mechanism of SOX2-OT.

Results

We discovered that hypoxia treatment decreased cell viability but increased cell apoptosis. Besides, lncRNA SOX2-OT expression was upregulated in hypoxic HCMs. Hereafter, we confirmed that SOX2-OT could negatively regulate miR-27a-3p levels by directly binding with miR-27a-3p, and miR-27a-3p also could negatively regulate SOX2-OT levels. Furthermore, knockdown of SOX2-OT promoted cell proliferation, migration, and invasion, but limited cell apoptosis. However, these effects were reversed by anti-miR-27a-5p. Besides, we verified that miR-27a-3p binding with the 3′UTR of TGFBR1 and SOX2-OT regulated TGFβR1 level by collaborating with miR-27a-3p in HCMs. Eventually, rescue assays validated that the influence of SOX2-OT silence or miR-27a-3p overexpression on cellular processes in cardiomyocytes injury was counteracted by TGFBR1 overexpression.

Conclusions

Long noncoding RNA SOX2-OT exacerbated hypoxia-induced cardiomyocytes injury by regulating miR-27a-3p/TGFβR1 axis, which may provide a novel insight for heart failure treatment.

MicroRNA regulatory networks in the pathogenesis of sarcopenia

Sarcopenia is an age‐related disease characterized by disturbed homeostasis of skeletal muscle, leading to a decline in muscle mass and function. Loss of muscle mass and strength leads to falls and fracture, and is often accompanied by other geriatric diseases, including osteoporosis, frailty and cachexia, resulting in a general decrease in quality of life and an increase in mortality. Although the underlying mechanisms of sarcopenia are still not completely understood, there has been a marked improvement in the understanding of the pathophysiological changes leading to sarcopenia in recent years. The role of microRNAs (miRNAs), especially, has been clearer in skeletal muscle development and homeostasis. miRNAs form part of a gene regulatory network and have numerous activities in many biological processes. Intervention based on miRNAs may develop into an innovative treatment strategy to conquer sarcopenia. This review is divided into three sections: firstly, the latest understanding of the pathogenesis of sarcopenia is summarized; secondly, increasing evidence for the involvement of miRNAs in the regulation of muscle quantity or quality and muscle homeostasis is highlighted; and thirdly, the possibilities and limitations of miRNAs as a treatment for sarcopenia are explored.

Micro-Ribonucleic Acid-216a Regulates Bovine Primary Muscle Cells Proliferation and Differentiation via Targeting SMAD Nuclear Interacting Protein-1 and Smad7

MicroRNAs (miRNAs), belonging to a class of evolutionarily conserved small noncoding RNA of ∼22 nucleotides, are widely involved in skeletal muscle growth and development by regulating gene expression at the post-transcriptional level. While the expression feature and underlying function of miR-216a in mammal skeletal muscle development, especially in cattle, remains to be further elucidated. The aim of this study was to investigate the function and mechanism of miR-216a during bovine primary muscle cells proliferation and differentiation. Herein, we found that the expression level of miR-216a both presented a downward trend during the proliferation and differentiation phases, which suggested that it might have a potential role in the development of bovine skeletal muscle. Functionally, during the cells proliferation phase, overexpression of miR-216a inhibited the expression of proliferation-related genes, reduced the cell proliferation status, and resulted in cells G1 phase arrest. In cells differentiation stages, overexpression of miR-216a suppressed myogenic maker genes mRNA, protein, and myotube formation. Mechanistically, we found that SNIP1 and smad7 were the directly targets of miR-216a in regulating bovine primary muscle cells proliferation and differentiation, respectively. Altogether, these findings suggested that miR-216a functions as a suppressive miRNA in development of bovine primary muscle cells via targeting SNIP1 and smad7.

MicroRNA-98-5p inhibits proliferation and metastasis in non-small cell lung cancer by targeting TGFBR1

MicroRNAs (miRNAs or miRs) have recently emerged as key regulators of various types of cancer, including non‑small cell lung cancer (NSCLC). The disrupted expression of miRNAs is associated with tumorigenesis and metastasis; however, the underlying mechanisms remain unclear. In this study, we demonstrate that miR‑98‑5p is downregulated in NSCLC and that miR‑98‑5p deficiency is associated with an advanced clinical stage and metastasis. A dual‑luciferase reporter assay was performed to confirm that transforming growth factor beta receptor 1 (TGFBR1), a key stimulator of tumor proliferation and metastasis, was a direct target of miR‑98‑5p. miR‑98‑5p overexpression resulted in the downregulation of TGFBR1 and the suppression of the viability, proliferation, migration and invasion of A549 and H1299 cells. Furthermore, miR‑98‑5p was demonstrated to be an efficient suppressor of tumor growth in an A549 subcutaneous xenograft tumor mouse model. Finally, miR‑98‑5p overexpression exerted a significant anti‑metastatic effect in a mouse model of pulmonary metastasis. On the whole, the results of the present study suggest that miR‑98‑5p/TGFBR1 may serve as promising targets for NSCLC therapy.