AUTHOR=Wu Xinmiao , Zhen Huimin , Liu Yan , Li Lu , Luo Yuzhu , Liu Xiu , Li Shaobin , Hao Zhiyun , Li Mingna , Hu Liyan , Qiao Lirong , Wang Jiqing 

TITLE=Tissue-Specific Expression of Circ_015343 and Its Inhibitory Effect on Mammary Epithelial Cells in Sheep

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.919162

DOI=10.3389/fvets.2022.919162

ISSN=2297-1769

ABSTRACT=Circular RNAs (circRNAs) are a kind of non-coding RNA that have important molecular function in mammary gland development and lactation of mammals. In our previous study, circ_015343 was found to be highly expressed in ovine mammary gland tissues at peak-lactation period using RNA sequencing (RNA-seq). In the study, the authenticity of circ_015343 was confirmed using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and Sanger sequencing. The circ_015343 was derived from complete ten exons of aminoadipic semialdehyde synthase (AASS), ranging from exon 2 to exon 11 and mainly located in cytoplasm of ovine mammary epithelial cells. The circRNA was found to be expressed in ovine eight tissues, with the highest expression level in mammary gland and the least expression in Longissimus dorsi muscle. The circ_015343 had a lower level of expression in a sheep breed with higher milk yield and milk fat content. The transfection of interfering circ_015343 into ovine mammary epithelial cells increased the viability and proliferation of the cells. The inhibition of circ_015343 also increased the expression levels of three milk fat synthesis marker genes: acetyl-coenzyme A carboxylase alpha (ACACA), fatty acid-binding protein 4 (FABP4) and sterol regulatory element-binding protein 1 (SREBP1), but decreased the expression level of its parent gene AASS. A circRNA-miRNA-mRNA interaction network showed that circ_015343 would bind some microRNAs (miRNAs) to regulate the expression of functional genes related to the development of mammary gland and lactation. This study contributes to a better understanding of the roles of circ_015343 in the mammary gland of sheep.