Circular RNA circFNDC3AL Upregulates BCL9 Expression to Promote Chicken Skeletal Muscle Satellite Cells Proliferation and Differentiation by Binding to miR-204.

Yuanhang Wei,Xiaoxu Shen,Yongtong Tian,Xinyi Zhang,Xinyan Li,Qing Zhu,Xiyu Zhao,Menggen Ma,Felix Kwame Amevor,Jihong Hu,Yao Zhang,Diyan Li,Huadong Yin,Wenling Huang,Jing Zhao,Jie Yi,Lei Yan

doi:10.3389/fcell.2021.736749

Abstract

Skeletal muscle is a heterogeneous tissue that is essential for initiating movement and maintaining homeostasis. The genesis of skeletal muscle is an integrative process that lasts from embryonic development to postnatal stages, which is carried out under the modulation of many factors. Recent studies have shown that circular RNAs (circRNAs), a class of non-coding RNAs, are involved in myogenesis. However, more circRNAs and their mechanisms that may regulate skeletal muscle development remain to be explored. Through in-depth analysis of our previous RNA-Seq data, circFNDC3AL was found to be a potentially functional circRNA highly expressed during embryonic development of chicken skeletal muscle. Therefore, in this study, we investigated the effect of circFNDC3AL on skeletal muscle development in chickens and found that circFNDC3AL promoted chicken skeletal muscle satellite cell (SMSC) proliferation and differentiation. To gain a thorough understanding of the exact modulatory mechanisms of circFNDC3AL in chicken skeletal muscle development, we performed target miRNA analysis of circFNDC3AL and found that circFNDC3AL has a binding site for miR-204. Subsequently, we demonstrated that miR-204 inhibited chicken SMSC proliferation and differentiation, which showed the opposite functions of circFNDC3AL. Furthermore, we identified the miR-204 target gene B-cell CLL/lymphoma 9 (BCL9) and validated that miR-204 had an inhibitory effect on BCL9, while the negative effect could be relieved by circFNDC3AL. In addition, we verified that BCL9 performed the same positive functions on chicken SMSC proliferation and differentiation as circFNDC3AL, as opposed to miR-204. In conclusion, our study identified a circRNA circFNDC3AL that upregulates BCL9 expression to promote the proliferation and differentiation of chicken SMSCs by binding to miR-204.

Highlights

Skeletal muscle is the largest tissue in the body of adult animals and is a crucial organ for initiating movements and maintaining homeostasis
We found the expression of circFNDC3AL gradually increased during embryonic development of chicken skeletal muscle, suggesting that circFNDC3AL might be functional in myogenesis
Cell cycle analysis revealed that the proportion of skeletal muscle satellite cell (SMSC) in the S and G2 phases was observably decreased by circFNDC3AL knockdown, whereas significantly increased by circFNDC3AL overexpression (P < 0.01; Figures 2G,H). These results indicate that circFNDC3AL promotes chicken SMSC proliferation

Summary

Introduction

Skeletal muscle is the largest tissue in the body of adult animals and is a crucial organ for initiating movements and maintaining homeostasis. The healthy development of skeletal muscle is important for the health of individual animals, otherwise it will lead to diseases such as Duchenne muscular dystrophy (DMD), which has been generally studied (Jin and Jeong, 2015). Skeletal muscle development is closely related to the activity of myogenic stem cells. The proliferation and differentiation of SMSCs give rise to the fusion of new myotubes and contribute to the formation of new myofibers (Das et al, 2019). With the development of bioinformatics, increasing transcripts and noncoding RNAs have been found to be involved in modulating skeletal muscle growth (Cesana et al, 2011; Peng et al, 2019)

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Conclusion