Morphological changes and functional circRNAs screening of rabbit skeletal muscle development.

BACKGROUND: The temporal expression pattern of circular RNAs (circRNAs) across developmental stages is essential for skeletal muscle growth and functional analysis. However, there are few analyses on the potential functions of circRNAs in rabbit skeletal muscle development. RESULTS: Initially, the paraffin sections showed extremely significant differences in the diameter, number, area and density of skeletal muscle fibers of the fetus, child, adult rabbit hind legs (P < 0.01). Then, RNA-seq libraries of these three stages were constructed. A total of 481 differentially expressed circRNAs (DE-circRNAs) and 5,658 differentially expressed genes (DEGs) were identified. Subsequently, DE-circRNAs, whose host genes were DEGs or non-DEGs, were analyzed by GO respectively. In the fetus vs. child group, up-regulated DE-circRNAs (whose host genes were DEGs) were related to muscle fiber structure, and down-regulated ones were related to mitosis. The up-regulated DE-circRNAs (whose host genes were non-DEGs) were involved in enzyme activity, methylation and glycosylation, and the down-regulated ones were involved in mitosis and catabolism. In the fetus vs. adult group, the up-regulated DE-circRNAs (whose host genes were DEGs) were related to skeletal muscle basic structure, and the down-regulated ones were also associated with cell proliferation. But the up-regulated DE-circRNAs (whose host genes were non-DEGs) were connected with regulation of histone ubiquitination, chromatin and organelles. The down-regulated DE-circRNAs were connected with the catabolism processes. In addition, novel_circ_0022663 and novel_circ_0005489, which might have coding potential, and novel_circ_0004210 and novel_circ_0001669, which might have miRNA sponge capability, were screened out. CONCLUSIONS: In this study, hind leg muscles of fetus, child and adult rabbits were collected for paraffin section and RNA-seq to observe the structural changes of skeletal muscle and obtain circRNA expression profiles at different stages. These data provided a catalog of circRNAs related to muscle development in New Zealand rabbits, allowing us to better understand the functional transitions in mammalian muscle development.

Dynamic changes of miRNAs in skeletal muscle development at New Zealand rabbits.

BACKGROUND: miRNA is one of the crucial roles in the complex and dynamic network that regulates the development of skeletal muscle. The landscape of skeletal muscle miRNAs from fetus to adult in New Zealand rabbits has not been revealed yet. RESULTS: In this study, nine RNA-seq libraries of fetus, child and adult rabbits' leg muscles were constructed. A total of 278 differentially expressed miRNAs (DEmiRNAs) were identified. In the fetus vs. child group, the main functional enrichments were involved in membrane and transport. Pathway enriched terms of up-regulated DEmiRNAs were connected with the differentiation and hypertrophy of skeletal muscle, and down-regulated ones were related to muscle structure and metabolic capacity. In the child vs. adult group, functions were associated to positioning and transportation, and pathways were relevant to ECM, muscle structure and hypertrophy. Finally, ocu-miR-185-3p and ocu-miR-370-3p, which had the most target genes, were identified as hub-miRNAs in these two groups. CONCLUSIONS: In short, we summarized the highly expressed and uniquely expressed DEmiRNAs of fetus, child and adult rabbits' leg muscles. Besides, the potential functional changes of miRNAs in two consecutive stages have been explored. Among them, the ocu-miR-185-3p and ocu-miR-370-3p with the most target genes were selected as hub-miRNAs. These data improved the understanding of the regulatory molecules of meat rabbit development, and provided a novel perspective for molecular breeding of meat rabbits.

Analysis of lncRNA in the skeletal muscle of rabbits at different developmental stages.

It is universally acknowledged that lncRNA plays an important role in the regulation of animal skeletal muscle development regulation. However, there is a lack of relevant research on lncRNA in rabbit skeletal muscle development. Thus, we explored the expression profiles of lncRNA in rabbits at three growth stages (2-week-old fetus, 6-week-old post-weaning, and 6-month-old adult) using RNA-seq. A total of 554 differentially expressed lncRNAs (235 up- and 319 down-regulated) were found between the post-weaning and fetus groups and 19 (7 up- and 12 down-regulated) between the post-weaning and adult groups and 429 (115 up- and 314 down-regulated) between the fetus and adult. The enrichment pathways in the post-weaning and fetus groups were mainly concentrated at AMPK and PI3K-Akt signaling pathways, and the co-expression results revealed that LINC-2903, LINC-2374, LINC-8591 plays a role in early maintenance of skeletal muscle development. The enriched pathways in the fetus and adult groups were mainly involved in PI3K-Akt signaling pathways with a strong association found in mTOR signaling pathways. Analysis of the co-expression results suggests that LINC-5617 may be involved in the proliferation of embryonic skeletal muscle cells, and that LINC-8613 and LINC-8705 may provide energy for postnatal skeletal muscle development. The specific roles of different lncRNAs in different developmental stages of New Zealand White rabbits obtained. This will contribute to the subsequent study on the regulatory mechanism of muscle development in New Zealand White rabbits.

miR-130a-3p regulates steroid hormone synthesis in goat ovarian granulosa cells by targeting the PMEPA1 gene.

MicroRNAs (miRNAs) are key epigenomic regulators of proliferation, differentiation, and secretion in cells involved in follicular development. We here studied the functional role of one such molecule, miR-130a-3p, in goat ovarian granulosa cells (GCs). High expression of this miRNA was evident in goat GCs by fluorescence in situ hybridization and suppressed estradiol and progesterone secretion from these cells, as determined by ELISA. miR-130a-3p was predicted to have a binding site for the 3' UTR of the prostate transmembrane protein androgen induced 1 gene (PMEPA1), and this was verified by a dual-luciferase reporter assay. PMEPA1 mRNA and protein expression were both found to be regulated by miR-130a-3p in GCs. Moreover, the overexpression or knockdown of PMEPA1 enhanced or suppressed estradiol and progesterone secretion from these cells, respectively. Furthermore, the secretion of estradiol and progesterone did not change significantly after the offsetting of PMEPA1 overexpression in GCs by miR-130a-3p. In summary, our present data indicate that miR-130a-3p inhibits the secretion of estradiol and progesterone in GCs by targeting PMEPA1. Our study thus provides seminal data and important new insights into the regulation of reproductive mechanisms in the nanny goat and other female mammals.