Circular RNA profiling reveals an abundant circLMO7 that regulates myoblasts differentiation and survival by sponging miR-378a-3p

Abstract

Circular RNAs (circRNAs) have been identified from various tissues and species, but their regulatory functions during developmental processes are not well understood. We examined circRNA expression profiles of two developmental stages of bovine skeletal muscle (embryonic and adult musculus longissimus) to provide first insights into their potential involvement in bovine myogenesis. We identified 12 981 circRNAs and annotated them to the Bos taurus reference genome, including 530 circular intronic RNAs (ciRNAs). One parental gene could generate multiple circRNA isoforms, with only one or two isoforms being expressed at higher expression levels. Also, several host genes produced different isoforms when comparing development stages. Most circRNA candidates contained two to seven exons, and genomic distances to back-splicing sites were usually less than 50 kb. The length of upstream or downstream flanking introns was usually less than 105 nt (mean≈11 000 nt). Several circRNAs differed in abundance between developmental stages, and real-time quantitative PCR (qPCR) analysis largely confirmed differential expression of the 17 circRNAs included in this analysis. The second part of our study characterized the role of circLMO7—one of the most down-regulated circRNAs when comparing adult to embryonic muscle tissue—in bovine muscle development. Overexpression of circLMO7 inhibited the differentiation of primary bovine myoblasts, and it appears to function as a competing endogenous RNA for miR-378a-3p, whose involvement in bovine muscle development has been characterized beforehand. Congruent with our interpretation, circLMO7 increased the number of myoblasts in the S-phase of the cell cycle and decreased the proportion of cells in the G0/G1 phase. Moreover, it promoted the proliferation of myoblasts and protected them from apoptosis. Our study provides novel insights into the regulatory mechanisms underlying skeletal muscle development and identifies a number of circRNAs whose regulatory potential will need to be explored in the future.

The Landscape of Non-Coding RNA in an Adult Pig Model of Intrauterine Growth Restriction

“…This results in the excess production of mitochondrial superoxide radicals and generates poor hepatic antioxidant defense systems [32]. Insulin signaling is the major pathway that controls glucose homeostasis by coordinating important metabolic processes, including glucose uptake, glycolysis, glucose oxidation, and glycogen synthesis in nearly all body tissues [56]. Previous studies have shown IUGR increases the mRNA levels of hepatic gluconeogenic genes and reduces the mRNA levels of insulin signaling genes in the liver [42].…”

Roles of lncRNAs and circRNAs in regulating skeletal muscle development

“…[95][96][97][98][99] Circ-ZNF609 promotes human myoblast proliferation through an unknown mechanism 95 ; however, circZfp609, which is the gene symbol of mouse ZNF609, sponges miR-194-5p to sequester its inhibition of BCL2-associated transcription factor 1 (BCLAF1) and repress myogenic differentiation by affecting the expression of Myf5 and MyoG. [95][96][97][98][99] Circ-ZNF609 promotes human myoblast proliferation through an unknown mechanism 95 ; however, circZfp609, which is the gene symbol of mouse ZNF609, sponges miR-194-5p to sequester its inhibition of BCL2-associated transcription factor 1 (BCLAF1) and repress myogenic differentiation by affecting the expression of Myf5 and MyoG.…”

“…[95][96][97][98][99] Circ-ZNF609 promotes human myoblast proliferation through an unknown mechanism 95 ; however, circZfp609, which is the gene symbol of mouse ZNF609, sponges miR-194-5p to sequester its inhibition of BCL2-associated transcription factor 1 (BCLAF1) and repress myogenic differentiation by affecting the expression of Myf5 and MyoG. 97,98 In addition, chicken circRBFOX2 promotes cell proliferation by enhancing the expression of cyclin D2 through sponging miR-206. It appears to function as a ceRNA for miR-378a-3p by targeting histone acetylation enzyme 4 (HDAC4).…”

Circular RNAs and competing endogenous RNA (ceRNA) networks

“…Combining these approaches, multiple labs have now characterized circRNAs across multiple cells types and species, and within various developmental and disease states. One very recent example of this type of analysis is described by Chen and colleagues who compared circRNA in fetal and adult muscle cells (5). …”

“…Many circRNAs described in Table 1 are proposed to work via titration of miRNAs. For example, Wei et al indicate that circLMO7 regulates myoblast differentiation and survival by sponging mir-378-3p (5). …”