C-type natriuretic peptide stimulates chicken myoblast differentiation through NPRB/NPRC receptors and metabolism pathway

Skeletal muscle development is closely related with the amount of meat production and its quality in chickens. Natriuretic peptides(NPs) play an important role in myotube formation and fat oxidation of skeletal muscle in animals. The effect of C-type natriuretic peptide(CNP), an important member of the NPs, and its underlying molecular mechanisms in skeletal muscle are incompletely understood. Treatment of myoblasts with CNP led to enhanced proliferation/differentiation and significantly upregulated(P<0.05) m RNA expression of the CNP receptors natriuretic peptide receptor B(NPRB) and the clearance receptor C(NPRC). In cells exposed to CNP, 142 differentially expressed genes(84 up-regulation and 58 down-regulation)(P<0.05) were identified by RNA-sequencing compared with those in control cells. Sixteen genes were significantly enriched(P<0.05) in the metabolic pathway, and six of them(phospholipase C β4, phospholipase C β2, phosphoglycerate mutase 1, creatine kinase B, peroxiredoxin 6 and CD38) were closely related to skeletal muscle development and differentially expressed. In conclusion, CNP stimulated differentiation of myoblasts by upregulating expression of the NPRB and NPRC receptors and enriching key genes in the metabolic pathway.

New Caspases’inhibitors belonging to the serpin superfamily:A novel key control point of apoptosis in mammalian tissues

The present report overviews a new family of bovine serpins able to inhibit pseudo-irreversibly initiator and effector caspases, a group of cysteine proteases in charge of cell dismantling during apoptosis, a finely regulated cell death process. The 8 members identified at the gene level showed a high homology with human SERPINA3 and were therefore designed bovSERPINA3-1 to A3-8. At least six of them are able to inhibit caspases. Two of them (bovSERPINA3-1 and A3-3) have been purified from bovine muscle and extensively investigated during these last years. After a general presentation of the serpin superfamily, the kinetic aspects of their interaction with human cas-pases 3 and 8 were studied and findings obtained suggest that caspases could be their target enzymes in living cells. In muscle and primary myoblast in culture, they showed an intracellular localization and because of their high level in blood, they can be exported. Two biological functions (potential regulator of apoptosis and expression during myoblast differentiation) were investigated and it was concluded that they are very likely a efficient regulator of apoptosis, a proposal supported by their high expression in proliferating myoblast (cell survival is essential during this differentiation phase) but not in myotubes.

A novel long non-coding RNA Myolinc regulates myogenesis through TDP-43 and Filip1

Myogenesis is a complex process required for skeletal muscle formation during embryonic development and for regeneration and growth of myofibers in adults. Accumulating evidence suggests that long non-coding RNAs （IncRNAs） play key roles in regulating cell fate decision and function in various tissues. However, the role of IncRNAs in the regulation of myogenesis remains poorly understood. In this study, we identifed a novel muscle-enriched IncRNA called ＇Myolinc （AK142388）＇, which we functionally characterized in the C2C12 myoblast cell line. Myolinc is predominately localized in the nucleus, and its levels increase upon induction of the differ-entiation. Knockdown of Myolinc impairs the expression of myogenic regulatory factors and formation of multi-nucleated myotubes in cultured myoblasts. Myolinc also regulates the expression of Filipl in a cis-manner. Similar to MyoUnc, knockdown of FiUpl inhi-bits myogenic differentiation. Furthermore, Myolinc binds to TAR DNA-binding protein 43 （TDP-43）, a DNA/RNA-binding protein that regulates the expression of muscle genes （e.g. Actal and MyoD）. Knockdown of TDP-43 inhibits myogenic differentiation. We also show that Myolinc-TDP-43 interaction is essential for the binding of TDP-43 to the promoter regions of muscle marker genes. Finally, we show that silencing of Myolinc inhibits skeletal muscle regeneration in adult mice. Altogether, our study identifies a novel IncRNA that controls key regulatory networks of myogenesis.

Bioactive biodegradable polycitrate nanoclusters enhances the myoblast differentiation and in vivo skeletal muscle regeneration via p38 MAPK signaling pathway

Complete skeletal muscle repair and regeneration due to severe large injury or disease is still a challenge.Biochemical cues are critical to control myoblast cell function and can be utilized to develop smart biomaterials for skeletal muscle engineering.Citric acid-based biodegradable polymers have received much attention on tissue engineering,however,their regulation on myoblast cell differentiation and mechanism was few investigated.Here,we find that citrate-based polycitrate-polyethylene glycol-polyethylenimine(POCG-PEI600)nanoclusters can significantly enhance the in vitro myoblast proliferation by probably reinforcing the mitochondrial number,promote the myotube formation and full-thickness skeletal muscle regeneration in vivo by activating the myogenic biomarker genes expression of Myod and Mhc.POCG-PEI600 nanoclusters could also promote the phosphorylation of p38 in MAP kinases(MAPK)signaling pathway,which led to the promotion of the myoblast differentiation.The in vivo skeletal muscle loss rat model also confirmed that POCG-PEI600 nanoclusters could significantly improve the angiogenesis,myofibers formation and complete skeletal muscle regeneration.POCG-PEI600 nanocluster could be also biodegraded into small molecules and eliminated in vivo,suggesting their high biocompatibility and biosafety.This study could provide a bioactive biomaterial-based strategy to repair and regenerate skeletal muscle tissue.

Differential expression of FOXO1 during development and myoblast differentiation of Qinchuan cattle and its association analysis with growth traits

Our previous work reported a relationship between FOXO1 mutations and growth of Qinchuan(QC) cattle. Here, we performed differential expression analysis of FOXO1 and its association analysis with growth traits in QC cattle. First, we measured the expression of the FOXO1 gene in nine tissues during three developmental stages. The results showed that FOXO1 was abundantly expressed in tissues of calves but was strongly repressed in adulthood, although there was significant transcription in skeletal muscle. FOXO1 expression showed gradual up-regulation during differentiation of primary bovine skeletal muscle cells.We also identified six SNPs of the bovine FOXO1 gene by sequencing DNA pools of samples from 488 individuals, and association analysis indicated that five SNPs were significantly associated with some growth traits in the QC population. We further analyzed four haplotype combinations of the six SNPs and found significant correlation with body length(P<0.01). In conclusion, FOXO1 participates in bovine myocyte differentiation and expression, and may be a strong candidate as a gene that affects growth traits that could be exploited in a QC cattle breeding program. More generally, our data provide a new theoretical basis for QC beef breeding and beef quality improvement.

Global Quantitative Proteomics Analysis Reveals the Downstream Signaling Networks of Msx1 and Msx2 in Myoblast Differentiation

The msh homeobox 1(Msx1)and msh homeobox 2(Msx2)coordinate in myoblast differentiation and also contribute to muscle defects if altered during development.Deciphering the downstream signaling networks of Msx1 and Msx2 in myoblast differentiation will help us to understand the molecular events that contribute to muscle defects.Here,the proteomics characteristics in Msx1-and Msx2-mediated myoblast differentiation was evaluated using isobaric tags for the relative and absolute quantification labeling technique(iTRAQ).The downstream regulatory proteins of Msx1-and Msx2-mediated differentiation were identified.Bioinformatics analysis revealed that these proteins were primarily associated with xenobiotic metabolism by cytochrome P450,fatty acid degradation,glycolysis/gluconeogenesis,arginine and proline metabolism,and apoptosis.In addition,our data show Acta1 was probably a core of the downstream regulatory networks of Msx1 and Msx2 in myoblast differentiation.