The proliferation and differentiation of myoblasts are essential for the regeneration and development of skeletal muscles. However, the process of skeletal muscle development in cattle is complex and needs to be further investigated. The microRNAs (miRNAs) are endogenous, small noncoding RNAs that play a critical role during skeletal muscle development. In this study, we evaluated the function of miR-885 in muscle development in cattle. The results found that the expression of miR-885 was gradually upregulated during myoblast proliferation, whereas progressively downregulated during myoblast differentiation. The overexpression of miR-885 promoted cell proliferation of myoblast in cattle. Moreover, we further noted that the overexpression miR-885 triggered the expression level of various marker genes involved in cell proliferation, including proliferating cell nuclear antigen (PCNA), cyclindependent kinase 2 (CDK2), and cyclin B1 (CCNB1). Furthermore, it was observed that overexpression of miR-885 inhibited cell differentiation, and significantly decreased messenger RNA and protein expression levels of myogenic differentiation 1 (MyoD1) and myogenin (MyoG) in primary bovine myoblasts. Moreover, the miR-885 inhibitor revealed that miR-885 inhibited cell proliferation and promoted cell differentiation. In addition, the overexpression of miR-885 markedly decreased MyoD1 expression in primary bovine myoblasts. The luciferase reporter assay, quantitative real-time polymerase chain reaction, and western blot (WB) further indicated that miR-885 directly binding to 3′ UTR of MyoD1 gene during transcriptional regulation.Conclusively, these results signified that miR-885 could be critical for the proliferation and differentiation in primary bovine myoblast cells by targeting the MyoD1 gene in cattle.

Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs (ncRNAs) involved in regulating skeletal muscle development by sponging miRNAs. In this study, we found that the circMYL1 expression was down-regulated during myoblast proliferation, while gradually up-regulated in myoblast differentiation. The potential role of circMYL1 was identified in the proliferation of bovine myoblast through mRNA and protein expression of proliferation marker genes (PCNA, CyclinD1, and CDK2), cell counting kit-8 assay, flow cytometry analysis, and 5-ethynyl 2′-deoxyuridine (EdU) assay. Analysis of the expression of differentiation marker genes (MyoD, MyoG, and MYH2) and immunofluorescence of Myosin heavy chain (MyHC) was used to assess cell differentiation. The proliferation analysis revealed that circMYL1 inhibited the proliferation of bovine primary myoblast. Furthermore, the differentiation analysis demonstrated that circMYL1 promoted the differentiation of bovine primary myoblast. The luciferase screening and RNA immunoprecipitation (RIP) assays found that circMYL1 could have interaction with miR-2400. Additionally, we demonstrated that miR-2400 promoted proliferation and inhibited differentiation of bovine primary myoblast, while circMYL1 may eliminate the effects of miR-2400, as showed by rescue experiments. Together, our results revealed that a novel circular RNA of circMYL1 could inhibit proliferation and promote differentiation of myoblast by sponging miR-2400.

No abstract

Background Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs (ncRNAs) involved in regulating skeletal muscle development by sponging microRNAs (miRNAs). This study aimed to define the circMYL1 molecular mechanisms in the regulation of bovine myogenesis and to disclose its regulatory mechanism through miR-2400 interaction. Methods The potential role of circMYL1 was identified in the proliferation of bovine myoblast through mRNA and protein expression of proliferation marker genes (PCNA, CyclinD1, and CDK2), cell counting kit-8 (CCK8) assay, flow cytometry analysis, and EdU assay. Analysis of the expression of differentiation marker genes (MyoD, MyoG, and MYH2) and immunofluorescence of Myosin heavy chain (MyHC) was used to assess cell differentiation. Results The proliferation analysis revealed that circMYL1 inhibited the proliferation of bovine primary myoblast. Furthermore, the differentiation analysis demonstrated that circMYL1 promoted the differentiation of bovine primary myoblast. The luciferase screening and RNA immunoprecipitation (RIP) assays found that circMYL1 could have interaction with miR-2400. Additionally, we demonstrated that miR-2400 promoted proliferation and inhibited differentiation of bovine primary myoblast, while circMYL1 may eliminate the effects of miR-2400, as showed by rescue experiments. Conclusions Our results revealed that a novel circular RNA of circMYL1 could inhibit proliferation and promote differentiation of myoblast by sponging miR-2400.

Marker-assisted selection is an important method for livestock breeding. In recent years, this technology has been gradually applied to livestock breeding to improve the body conformation traits. In this study, the LRRC8B (Leucine Rich Repeat Containing 8 VRAC Subunit B) gene was selected to evaluate the association between its genetic variations and the body conformation traits in two native sheep breeds in China. Four body conformation traits, including withers height, body length, chest circumference, and body weight, were collected from 269 Chaka sheep. We also collected the body length, chest width, withers height, chest depth, chest circumference, cannon bone circumference, and height at hip cross of 149 Small-Tailed Han sheep. Two different genotypes, ID and DD, were detected in all sheep. Our data showed that the polymorphism of the LRRC8B gene was significantly associated with chest depth (p < 0.05) in Small-Tailed Han sheep, and it is greater in sheep with DD than those with ID. In conclusion, our data suggested that the LRRC8B gene could serve as a candidate gene for marker-assisted selection in Small-Tailed Han sheep.