Myristoleic acid produced by enterococci reduces obesity through brown adipose tissue activation

OBJECTIVE

Dietary fibre has beneficial effects on energy metabolism, and the majority of studies have focused on short-chain fatty acids produced by gut microbiota. Ginseng has been reported to aid in body weight management, however, its mechanism of action is not yet clear. In this study, we focused on the potential modulating effect of ginseng on gut microbiota, aiming to identify specific strains and their metabolites, especially long-chain fatty acids (LCFA), which mediate the anti-obesity effects of ginseng.

DESIGN

Db/db mice were gavaged with ginseng extract (GE) and the effects of GE on gut microbiota were evaluated using 16S rDNA-based high throughput sequencing. To confirm the candidate fatty acids, untargeted metabolomics analyses of the serum and medium samples were performed.

RESULTS

We demonstrated that GE can induce Enterococcus faecalis, which can produce an unsaturated LCFA, myristoleic acid (MA). Our results indicate that E. faecalis and its metabolite MA can reduce adiposity by brown adipose tissue (BAT) activation and beige fat formation. In addition, the gene of E. faecalis encoding Acyl-CoA thioesterases (ACOTs) exhibited the biosynthetic potential to synthesise MA, as knockdown (KD) of the ACOT gene by CRISPR-dCas9 significantly reduced MA production. Furthermore, exogenous treatment with KD E. faecalis could not reproduce the beneficial effects of wild type E. faecalis, which work by augmenting the circulating MA levels.

CONCLUSIONS

Our results demonstrated that the gut microbiota-LCFA-BAT axis plays an important role in host metabolism, which may provide a strategic advantage for the next generation of anti-obesity drug development.

Enzymatic biotransformation of ginsenoside Rb1 to 20(S)-Rg3 by recombinant β-glucosidase from Microbacterium esteraromaticum

Microbacterium esteraromaticum was isolated from ginseng field. The β-glucosidase gene (bgp1) from M. esteraromaticum was cloned and expressed in Escherichia coli BL21 (DE3). The bgp1 gene consists of 2,496 bp encoding 831 amino acids which have homology to the glycosyl hydrolase family 3 protein domain. The recombinant β-glucosidase enzyme (Bgp1) was purified and characterized. The molecular mass of purified Bgp1 was 87.5 kDa, as determined by SDS-PAGE. Using 0.1 mg ml(-1) enzyme in 20 mM sodium phosphate buffer at 37°C and pH 7.0, 1.0 mg ml(-1) ginsenoside Rb1 was transformed into 0.444 mg ml(-1) ginsenoside Rg3 within 6 h. The Bgp1 sequentially hydrolyzed the outer and inner glucose attached to the C-20 position of ginsenosides Rb1. Bgp1 hydrolyzed the ginsenoside Rb1 along the following pathway: Rb1 → Rd → 20(S)-Rg3. This is the first report of the biotransformation of ginsenoside Rb1 to ginsenoside 20(S)-Rg3 using the recombinant β-glucosidase.

Enzymatic biotransformation of ginsenoside Rb1 to compound K by recombinant β-glucosidase from Microbacterium esteraromaticum

We cloned and characterized a β-glucosidase (bgp3) gene from Microbacterium esteraromaticum isolated from ginseng field. The bgp3 gene consists of 2,271 bp encoding 756 amino acids which have homology to the glycosyl hydrolase family 3 protein domain. The molecular mass of purified Bgp3 was 80 kDa, as determined by SDS-PAGE. The enzyme (Bgp3) catalyzed the conversion of ginsenoside Rb1 to the more pharmacologically active minor ginsenoside Rd and compound K. The Bgp3 hydrolyzed the outer glucose moiety attached to the C-20 position of ginsenoside Rb1, followed by hydrolysis of the inner glucose moiety attached to the C-3 position. Using 0.1 mg mL(-1) enzyme in 20 mM sodium phosphate buffer at 40 °C and pH 7.0, 1.0 mg mL(-1) ginsenoside Rb1 was transformed into 0.46 mg mL(-1) compound K within 60 min with a corresponding molar conversion yield of 77%. Bgp3 hydrolyzed the ginsenoside Rb1 along the following pathway: Rb1 → Rd → compound K.

Biotransformation of Ginsenoside Rb1 to Prosapogenins, Gypenoside XVII, Ginsenoside Rd, Ginsenoside F2, and Compound K by Leuconostoc mesenteroides DC102

Ginsenoside Rb₁is the main component in ginsenosides. It is a protopanaxadiol-type ginsenoside that has a dammarane-type triterpenoid as an aglycone. In this study, ginsenoside Rb₁ was transformed into gypenoside XVII, ginsenoside Rd, ginsenoside F₂ and compound K by glycosidase from Leuconostoc mesenteroides DC102. The optimum time for the conversion was about 72 h at a constant pH of 6.0 to 8.0 and the optimum temperature was about 30℃. Under optimal conditions, ginsenoside Rb₁ was decomposed and converted into compound K by 72 h post-reaction (99%). The enzymatic reaction was analyzed by highperformance liquid chromatography, suggesting the transformation pathway: ginsenoside Rb₁→ gypenoside XVII and ginsenoside Rd→ginsenoside F₂→compound K.

Comparative Analysis of the Rats' Gut Microbiota Composition in Animals with Different Ginsenosides Metabolizing Activity

Following oral intake of Panax ginseng, major ginsenosides are metabolized to deglycosylated ginsenosides by gut microbiota before absorption into the blood. As the composition of gut microbiota varies between individuals, metabolic activities are significantly different. We selected 6 rats with low efficiency metabolism (LEM) and 6 rats with high efficiency metabolism (HEM) from 60 rats following oral administration of Panax ginseng extract, and analyzed their gut microbiota composition using Illumina HiSeq sequencing of the 16S rRNA gene. The components of gut microbiota between the LEM and HEM groups were significantly different. Between the 2 groups, S24-7, Alcaligenaceae, and Erysipelotrichaceae occupied most OTUs of the HEM group, which was notably higher than the LEM group. Furthermore, we isolated Bifidobacterium animalis GM1 that could convert the ginsenoside Rb1 to Rd. The result implies that these specific intestinal bacteria may dominate the metabolism of Panax ginseng.

Anti-inflammatory action of Athyrium multidentatum extract suppresses the LPS-induced TLR4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial part of Athyrium multidentatum (Doll.) Ching (AM) is widely used in the northeastern region of China as an edible wild herb, but its medicinal value, especially its anti-inflammatory effect, has not been fully explored.

AIM OF THE STUDY

To investigate the anti-inflammatory activity of AM and clarify the anti-inflammatory mechanism involving the TLR4 signaling pathway using a lipopolysaccharide (LPS)-induced inflammatory model.

MATERIALS AND METHODS

AM ethanol extract was used as the experimental material to investigate the effect that the extract has on the production of pro-inflammatory mediators (NO, PGE_2, TNF-α, IL-1β and IL-6); changes in LPS-induced peritoneal macrophages (PMs); and TLR4-mediated intracellular events, including MAPKs (ERK, JNK, and p38) and IκB-α in the MyD88-dependant pathway and IRF3, STAT1, and STAT3 in the TRIF-dependent pathway. In in vivo experiments, we established an LPS-induced acute lung injury (ALI) model and investigated the cell count and cytokine (TNF-α, IL-1β and IL-6) levels in bronchoalvelar lavage fluid (BALF) of C57BL6 mice. Histological changes in the lung tissues were observed with H&E staining.

RESULTS

AM extract inhibited NO and PGE₂ by suppressing their synthetase (iNOS and COX-2) gene expression in LPS-induced PMs; the secretion of IL-6, IL-1β, and TNF-α also deceased via the down-regulation of mRNA levels. Furthermore, the TLR4-mediated intracellular events involved the phosphorylated forms of MAPKs (ERK, JNK) and IκB-α in the MyD88-dependent pathway and the TRIF-dependent pathway (IRF3, STAT1, STAT3), and the relevant proteins were expressed at low levels in the AM extract groups. In in vivo experiments, the cell count and cytokine (TNF-α, IL-1β and IL-6) levels in BALF decreased significantly in a dose-dependent manner in the AM extract groups. The lung tissue structure exhibited dramatic damage in the LPS group, and the damaged area decreased in the AM extract groups; in particular, the effect of 10 mg/kg extract was similar to that of the positive control dexamethasone (DEX).

CONCLUSION

The findings demonstrate that AM protects against LPS-induced acute lung injury by suppressing TLR4 signaling, provide scientific evidence to support further study of the safety of anti-inflammatory drugs and indicate that AM can be used as an anti-inflammatory and anti-injury agent to prevent pneumonia caused by microbial infection.

Biotransformation of Panax ginseng extract by rat intestinal microflora: identification and quantification of metabolites using liquid chromatography-tandem mass spectrometry

BACKGROUND

In general, after Panax ginseng is administered orally, intestinal microbes play a crucial role in its degradation and metabolization process. Studies on the metabolism of P. ginseng by microflora are important for obtaining a better understanding of their biological effects.

METHODS

In vitro biotransformation of P. ginseng extract by rat intestinal microflora was investigated at 37°C for 24 h, and the simultaneous determination of the metabolites and metabolic profile of P. ginseng saponins by rat intestinal microflora was achieved using LC-MS/MS.

RESULTS

A total of seven ginsenosides were detected in the P. ginseng extract, including ginsenosides Rg1, Re, Rf, Rb1, Rc, Rb2, and Rd. In the transformed P. ginseng samples, considerable amounts of deglycosylated metabolite compound K and Rh1 were detected. In addition, minimal amounts of deglycosylated metabolites (ginsenosides Rg2, F1, F2, Rg3, and protopanaxatriol-type ginsenosides) and untransformed ginsenosides Re, Rg1, and Rd were detected at 24 h. The results indicated that the primary metabolites are compound K and Rh1, and the protopanaxadiol-type ginsenosides were more easily metabolized than protopanaxatriol-type ginsenosides.

CONCLUSION

This is the first report of the identification and quantification of the metabolism and metabolic profile of P. ginseng extract in rat intestinal microflora using LC-MS/MS. The current study provided new insights for studying the metabolism and active metabolites of P. ginseng.

Stenotrophomonas ginsengisoli sp. nov., isolated from a ginseng field

A Gram-negative, non-spore-forming, rod-shaped bacterium, designated strain DCY01T, was isolated from soil from a ginseng field in South Korea and was characterized in order to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain DCY01T belonged to the Gammaproteobacteria and was most closely related to Stenotrophomonas koreensis KCTC 12211T (98.4 % similarity), Stenotrophomonas humi R-32729T (97.2 %), Stenotrophomonas terrae R-32768 (97.1 %), Stenotrophomonas maltophilia DSM 50170T (96.9 %) and Stenotrophomonas nitritireducens DSM 12575T (96.8 %). Chemotaxonomic analyses revealed that strain DCY01T possessed a quinone system with Q-8 as the predominant compound, and iso-C15 : 0 (28.2 %), C16 : 0 10-methyl (13.2 %), iso-C15 : 1 F (10.8 %) and C15 : 0 (7.5 %) as major fatty acids, corroborating assignment of strain DCY01T to the genus Stenotrophomonas. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The results of DNA–DNA hybridization and physiological and biochemical tests clearly demonstrated that strain DCY01T represents a species distinct from recognized Stenotrophomonas species. Based on these data, DCY01T (=KCTC 12539T=NBRC 101154T) should be classified as the type strain of a novel species of the genus Stenotrophomonas, for which the name Stenotrophomonas ginsengisoli sp. nov. is proposed.

Isolation and characterization of novel ginsenoside-hydrolyzing glycosidase from Microbacterium esteraromaticum that transforms ginsenoside Rb2 to rare ginsenoside 20(S)-Rg3

Ginsenoside Rb2 was transformed by recombinant glycosidase (Bgp2) into ginsenosides Rd and 20(S)-Rg3. The bgp2 gene consists of 2,430 bp that encode 809 amino acids, and this gene has homology to the glycosyl hydrolase family 2 protein domain. SDS-PAGE was used to determine that the molecular mass of purified Bgp2 was 87 kDa. Using 0.1 mg ml(-1) of enzyme in 20 mM sodium phosphate buffer at 40 °C and pH 7.0, 1.0 mg ml(-1) ginsenoside Rb2 was transformed into 0.47 mg ml(-1) ginsenoside 20(S)-Rg3 within 120 min, with a corresponding molar conversion yield of 65 %. Bgp2 hydrolyzed the ginsenoside Rb2 along the following pathway: Rb2 → Rd → 20(S)-Rg3. This is the first report of the biotransformation of ginsenoside Rb2 to ginsenoside 20(S)-Rg3 using the recombinant glycosidase.

Biotransformation of gypenoside XVII to compound K by a recombinant β-glucosidase

OBJECTIVE

To study the β-glucosidase gene (bgy1) from Lactobacillus brevis that was cloned and expressed in Escherichia coli BL21 (DE3) and then using it for the biotransformation of gypenoside XVII.

RESULTS

The bgy1 gene consists of 2283 bp encoding 761 amino acids, with homology to the glycosyl hydrolase family-3 protein domain. The enzyme (Bgy1) hydrolyzed the glucose moieties at the C-3 position and the outer glucose moieties at the C-20 position of gypenoside XVII. Using 0.1 mg enzyme ml(-1) in 20 mM sodium phosphate buffer at 30 °C and pH 6.0, 1 mg gypenoside XVII ml(-1) was transformed into 0.58 mg compound K ml(-1) within 6 h, with a corresponding molar conversion yield of 89 %.

CONCLUSION

The recombinant Bgy1 is considered potentially useful for the practical preparation of compound K.

Enzymatic Transformation of Ginsenoside Rb1 by Lactobacillus pentosus Strain 6105 from Kimchi

Ginsenoside (ginseng saponin), the principal component of ginseng, is responsible for the pharmacological and biological activities of ginseng. We isolated lactic acid bacteria from Kimchi using esculin agar, to produce β-glucosidase. We focused on the bio-transformation of ginsenoside. Phylogenetic analysis was performed by comparing the 16S rRNA sequences. We identified the strain as Lactobacillus (strain 6105). In order to determine the optimal conditions for enzyme activity, the crude enzyme was incubated with 1 mM ginsenoside Rb1 to catalyse the reaction. A carbon substrate, such as cellobiose, lactose, and sucrose, resulted in the highest yields of β-glucosidase activity. Biotransformations of ginsenoside Rb1 were analyzed using TLC and HPLC. Our results confirmed that the microbial enzyme of strain 6105 significantly transformed ginsenoside as follows: Rb1→gypenoside XVII, Rd→F2 into compound K. Our results indicate that this is the best possible way to obtain specific ginsenosides using microbial enzymes from 6105 culture.

Cloning and Characterization of Ginsenoside-Hydrolyzing β-Glucosidase from Lactobacillus brevis That Transforms Ginsenosides Rb1 and F2 into Ginsenoside Rd and Compound K

The ginsenoside-hydrolyzing β-glucosidase gene (bgy2) was cloned from Lactobacillus brevis. We expressed this gene in Escherichia coli BL21(DE3), isolated the resulting protein, and then utilized the enzyme for the biotransformation of ginsenosides. The bgy2 gene contains 2,223 bp, and encodes a protein of 741 amino acids that is a member of glycosyl hydrolase family 3. β-Glucosidase (Bgy2) cleaved the outer glucose moieties of ginsenosides at the C-20 position, and the inner glucose at the C-3 position. Under optimal conditions (pH 7.0, 30°C), we used 0.1 mg/ml Bgy2 in 20 mM sodium phosphate buffer (PBS) for enzymatic studies. In these conditions, 1.0 mg/ml ginsenoside Rb1 and ginsenoside F2 were converted into 0.59 mg/ml ginsenoside Rd and 0.72mg/ml compound K, with molar conversion productivities of 69% and 91%, respectively. In pharmaceutical and commercial industries, this recombinant Bgy2 would be suitable for producting ginsenoside Rd and compound K.

Ginsenoside metabolite 20(S)-protopanaxatriol from Panax ginseng attenuates inflammation-mediated NLRP3 inflammasome activation

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng C.A. Meyer (Araliaceae), has been used in traditional medicine for preventive and therapeutic purposes in Asian countries. One of the active ginsenoside metabolites, 20(S)-Protopanaxatriol (PPT), has been associated with diverse pharmacological effects, including anti-inflammatory properties.

AIM OF THE STUDY

Although the capacity of PPT as an anti-inflammatory agent has been studied, this study aimed to explore the intrinsic mechanism of PPT in regulating inflammasome activation-mediated inflammatory responses in experimental models.

MATERIALS AND METHODS

Lipopolysaccharide (LPS)-primed peritoneal macrophages in vitro was used to study the role of PPT on inflammasome activation. LPS-induced septic shock and monosodium urate (MSU)-induced murine peritonitis models were employed for in vivo evaluations.

RESULTS

PPT attenuated NLRP3 inflammasome activation and also reduced ASC oligomerization, leading to attenuation of interleukin (IL)-1β secretion. Further, PPT inhibited IL-1β secretion in both LPS-induced septic shock and MSU-induced mouse peritonitis models.

CONCLUSIONS

This study revealed that ginsenoside metabolite PPT, inhibits inflammation-mediated inflammasome activation and supported the traditional use of ginseng in treating various inflammatory disorders.

Brown adipose tissue activation by ginsenoside compound K treatment ameliorates polycystic ovary syndrome

BACKGROUND AND PURPOSE

Polycystic ovary syndrome (PCOS) is a common metabolic and endocrine disease affecting women of reproductive age. Due to its complex etiology, there is no effective cure for PCOS currently. Brown adipose tissue (BAT) activity is significantly decreased in PCOS patients and BAT activation has beneficial effects on PCOS animal models. Here, we investigated the therapeutic effect of ginsenoside compound K (CK) on an animal model of PCOS and its mechanism of BAT activation EXPERIMENTAL APPROACH: Primary brown adipocyte, Db/Db mice and dehydroepiandrosterone (DHEA)-induced PCOS rats were used. The core body temperature, oxygen consumption, energy metabolism related gene and protein expression were assessed to identify the function of CK on energy metabolism. Estrous cycle, serum sex hormone, ovarian steroidogenic enzyme gene expression and ovarian morphology were evaluated following CK treatment.

KEY RESULTS

Our results indicated that CK treatment could significantly protect against body weight gain in Db/Db mice via BAT activation. Furthermore, we found that CK treatment could normalize hyperandrogenism, estrous cyclicity, normalize steroidogenic enzyme expression and decrease the number of cystic follicles in PCOS rats. Interestingly, as a potential endocrine intermediate, C-X-C motif chemokine ligand-14 protein (CXCL14) was significantly upregulated following CK administration. In addition, exogenous CXC14 supplementation was found to reverse DHEA-induced PCOS in a phenotypically similar manner to CK treatment.

CONCLUSION AND IMPLICATIONS

In summary, CK treatment significantly activates BAT, increases CXCL14 expression and ameliorates PCOS. These findings suggest that CK might be a potential drug candidate for PCOS treatment.

Bioconversion of ginsenoside rb1 into compound k by Leuconostoc citreum LH1 isolated from kimchi

About 40 different types of ginsenoside (ginseng saponin), a major pharmacological component of ginseng, have been identified along with their physiological activities. Among these, compound K has been reported to prevent the development of and the metastasis of cancer by blocking the formation of tumors and suppressing the invasion of cancerous cells. In this study, ginsenoside Rb1 was converted into compound K via interaction with the enzyme secreted by β-glucosidase active bacteria, Leuconostoc citreum LH1, extracted from kimchi. The optimum time for the conversion of Rb1 to compound K was about 72 hrs at a constant pH of 6.0 and an optimum temperature of about 30°C. Under optimal conditions, ginsenoside Rb1 was decomposed and converted into compound K by 72 hrs post-reaction (99%). Both TLC and HPLC were used to analyze the enzymatic reaction. Ginsenoside Rb1 was consecutively converted to ginsenoside Rd, F2, and compound K via the hydrolyses of 20-C β-(1 → 6)-glucoside, 3-C β-(1 → 2)-glucoside, and 3-C β-glucose of ginsenoside Rb1.

Purification and Characterization of Pasteuricin Produced by Staphylococcus pasteuri RSP-1 and Active against Multidrug-Resistant Staphylococcus aureus

Staphylococcus aureus is an important pathogen implicated in various diseases, including staphylococcal food poisoning. Bacteriocins are considered safe and effective antimicrobial substances for the prevention of the growth of pathogenic bacteria. In this article, we describe the purification and characterization of pasteuricin, a novel bacteriocin produced by Staphylococcus pasteuri RSP-1. A cell-free supernatant of S. pasteuri RSP-1 exerted strong antimicrobial activity against staphylococci, including methicillin-resistant S. aureus (MRSA), and gram-positive bacteria. The loss of antimicrobial activity upon treatment with proteolytic enzymes confirmed the proteinaceous nature of pasteuricin. A rapid and pronounced bactericidal effect of pasteuricin was confirmed by a live-dead bacterial viability assay. To our knowledge, pasteuricin is the first reported S. pasteuri bacteriocin that inhibits S. aureus. Because pasteuricin is characterized by strong antimicrobial activity and high stability, it has potential as an alternative antimicrobial agent to antibiotics.

Fecal transplant from myostatin deletion pigs positively impacts the gut-muscle axis

The host genome may influence the composition of the intestinal microbiota, and the intestinal microbiota has a significant effect on muscle growth and development. In this study, we found that the deletion of the myostatin (MSTN) gene positively regulates the expression of the intestinal tight junction-related genes TJP1 and OCLN through the myosin light-chain kinase/myosin light chain pathway. The intestinal structure of MSTN^-/- pigs differed from wild-type, including by the presence of a thicker muscularis and longer plicae. Together, these changes affect the structure of intestinal microbiota. Mice transplanted with the intestinal microbiota of MSTN^-/- pigs had myofibers with larger cross-sectional areas and higher fast-twitch glycolytic muscle mass. Microbes responsible for the production of short-chain fatty acids (SCFAs) were enriched in both the MSTN^-/- pigs and recipient mice, and SCFAs levels were elevated in the colon contents. We also demonstrated that valeric acid stimulates type IIb myofiber growth by activating the Akt/mTOR pathway via G protein-coupled receptor 43 and ameliorates dexamethasone-induced muscle atrophy. This is the first study to identify the MSTN gene-gut microbiota-SCFA axis and its regulatory role in fast-twitch glycolytic muscle growth.

The ginsenoside Rh2 protects porcine oocytes against aging and oxidative stress by regulating SIRT1 expression and mitochondrial activity

Post-ovulatory aging, a major problem faced by oocytes cultured in vitro, causes oxidative damage and mitochondrial dysfunction in oocytes. The ginsenoside Rh2 is one of the main monomeric components of ginseng, but its effects on porcine oocytes are unknown. In the present study, in vitro aging (IVA) and accelerated induction of aging using H₂O₂ resulted in DNA damage and an increased incidence of abnormal spindle formation in porcine oocytes. Rh2 supplementation increased the antioxidant capacity, reduced the occurrence of early apoptosis, and improved the development of in vitro fertilized blastocysts. It also rescued the abnormal aggregation of mitochondria and the decrease of the mitochondrial membrane potential under mitochondrial dysfunction. Meanwhile, Rh2 enhanced mRNA expression of the anti-aging and mitochondrial biogenesis-related genes silent information regulator of transcription 1 (SIRT1) and peroxisome proliferator-activated receptor coactivator 1-α (PGC-1α), and the antioxidant gene superoxide dismutase 1 (SOD1). The protection of porcine oocytes against aging and oxidative stress by Rh2 was confirmed using the SIRT1-specific inhibitor EX-527. Our results reveal that Rh2 upregulates SIRT1/PGC-1α to enhance mitochondrial function in porcine oocytes and improve their quality. Our study indicates that Rh2 can be used to prevent mitochondrial dysfunction in oocytes.

miR-455-3p Is Negatively Regulated by Myostatin in Skeletal Muscle and Promotes Myoblast Differentiation

Myostatin (MSTN) is a growth and differentiation factor that regulates proliferation and differentiation of myoblasts, which in turn controls skeletal muscle growth. It may regulate myoblast differentiation by influencing miRNA expression, and the present study aimed to clarify its precise mechanism of action. Here, we found that MSTN^-/- pigs showed an overgrowth of skeletal muscle and upregulated miR-455-3p level. Intervention of MSTN expression using siMSTN in C2C12 myoblasts also showed that siMSTN significantly increased the expression of miR-455-3p. It was found that miR-455-3p directly targeted the 3'-untranslated region of Smad2 by dual-luciferase assay. qRT-PCR, Western blotting, and immunofluorescence analyses indicated that miR-455-3p overexpression or Smad2 silencing in C2C12 myoblasts significantly promoted myoblast differentiation. Furthermore, siMSTN significantly increased the expression of GATA3. The levels of miR-455-3p were considerably reduced in C2C12 myoblasts following GATA3 knockdown. Consistently, GATA3 knockdown also reduced the enhanced miR-455-3p expression caused by siMSTN. Finally, we illustrated that GATA3 has a role in myoblast differentiation regulation. Taken together, we identified the expression profiles of miRNAs in MSTN^-/- pigs and found that miR-455-3p positively regulates myoblast differentiation. In addition, we revealed that MSTN acts through the GATA3/miR-455-3p/Smad2 cascade to regulate muscle development.