Abstract
Simple SummaryCircular RNAs are novel long non-coding RNA involved in the regulation of gene expression. Recently, the expression of circRNAs was characterized in testes of humans and bulls. However, the profiling of circRNAs and their potential biological functions in boar testicular development are yet to be known. In this study we characterized expression and biological roles of circRNAs in piglet (30 d) and adult (210 d) boar testes by high-throughput sequencing. We identified a large number of circRNAs during testicular development, of which 2326 circRNAs exhibited a significantly differential expression. Gene ontology analysis revealed that these differential expressed circRNAs might be involved in regulating spermatogenesis and hormone biosynthesis. Overall, the results indicate that circRNAs are abundantly expressed in boar testes and exhibit dynamic changes during testicular development. These findings will enable the provision of potential molecular markers for both breeding of elite boars and evaluating developmental status of boar testes.Testicular development is critical for male animals’ reproduction and is tightly regulated by epigenetic factors. Circular RNAs (circRNAs) were recently identified in the testes of humans and bulls. However, the expression profile of circRNAs and their potential biological functions in boar testicular development remain unclear. We identified 34,521 and 31,803 circRNAs in piglet (30 d) and adult (210 d) boar testes by high-throughput sequencing, respectively. Bioinformatics analysis revealed that these circRNAs are widely distributed on autosomes and sex chromosomes. Some of the host genes can generate multiple circRNAs. A total of 2326 differentially expressed circRNAs (DECs) derived from 1526 host genes was found in testicular development, of which 1003 circRNAs were up-regulated in adult boar testes and 1323 circRNAs were down-regulated. Furthermore, gene ontology analysis of host genes of DECs revealed that these circRNAs are mainly involved in regulating spermatogenesis, cilia motility, and hormone biosynthesis. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the DECs are markedly enriched to stem cell pluripotency regulation, tight junctions, adhesion junctions, and cAMP signaling pathway. These results indicate that circRNAs are abundantly expressed in boar testes and exhibit dynamic changes during testicular development.
Highlights
The domestic pig provides enriched animal derived food products for humans, and is increasingly used as an animal model for human disease in biomedicine, while the boar fertility in the swine industry determines the productive efficiency of commercial pork and the progress of genetics in the pig-breeding program
Testicular interstitial cells are uniformly distributed around seminiferous tubules, and spermatogonia are neatly arranged along the seminiferous tubule basement membranes
The results show that circular RNA (circRNA) exhibit a clear differential expression during testicular development, and that the circRNAs involved in gene expression regulation, histone acetylation, motor behavior, small GTPase-mediated signal transduction and extracellular exosomes are significantly upregulated (p Value < 0.05)
Summary
The domestic pig provides enriched animal derived food products for humans, and is increasingly used as an animal model for human disease in biomedicine, while the boar fertility in the swine industry determines the productive efficiency of commercial pork and the progress of genetics in the pig-breeding program. Testis is the main reproductive organ of male animals, the functions of which are spermatogenesis and androgen secretion. Androgens are produced by testicular mesenchymal cells and play significant roles in maintaining spermatogenesis and accessory sexual gland development. Spermatogenesis and androgen secretion both affect the physiological reproductive processes of male animals [3]. Mammalian testicular development and spermatogenesis are highly precise and orderly processes with clearly distinguished stages. Testicle-specific genes are expressed in strict accordance with temporal and spatial factors at different developmental stages and participate in the regulation of many aspects of sexual development and function under the action of numerous different factors [4,5]. The normal development of testes requires the regulation of cell-cycle-related genes such as cyclin and cyclin-dependent kinase (CDK) [6] as well as meiosis-related genes such as deleted in azoospermia (DAZ) family genes [7]; stimulated by retinoic acid gene
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