Circular RNA Vav3 sponges gga-miR-375 to promote epithelial-mesenchymal transition

Authors: ZHANG, XINHENG - South China Agricultural University; YAN, YIMING - South China Agricultural University; LIN, WENCHENG - South China Agricultural University; LI, AIJUN - Jinan University; Zhang, Huanmin; LEI, XIAOYA - South China Agricultural University; DAI, ZHENKAI - South China Agricultural University; LI, XINJIAN - South China Agricultural University; LI, HONGXIN - South China Agricultural University; CHEN, WEIGUO - South China Agricultural University; CHEN, FENG - South China Agricultural University; MA, JINGYUN - South China Agricultural University; XIE, QINGMEI - South China Agricultural University

Submitted to: RNA Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2018
Publication Date: 1/15/2019
Publication URL: https://handle.nal.usda.gov/10113/6473330
Citation: Zhang, X., Yan, Y., Lin, W., Li, A., Zhang, H., Lei, X., Dai, Z., Li, X., Li, H., Chen, W., Chen, F., Ma, J., Xie, Q. 2019. Circular RNA Vav3 sponges gga-miR-375 to promote epithelial-mesenchymal transition. RNA Biology. 16(1):118-132. https://doi.org/10.1080/15476286.2018.1564462.
DOI: https://doi.org/10.1080/15476286.2018.1564462

Interpretive Summary: Increasing attention in the genomics research fields has been focusing on non-coding RNAs, that is, unlike the message RNAs that code for proteins, these types of RNAs do not code for any such traditional protein product. Two types of such non-coding RNAs are known by the scientific world as circular RNA and microRNA, both of which act as gene expression regulators. By RNA sequencing and microarray analyses, one circRNA, known as circ-Vav3, and one microRNA, known as miR-375, were found jointly affecting a subgroup of avian leukosis virus, the J-group, induced tumor formation in chicken. This finding is of importance in advancing the basic understanding on genetic resistance mechanism against J-group avian leukosis virus induced tumors and in developing new strategies for genetic improvement for the disease resistance through selection, thereby benefiting the poultry industry and consumers.

Technical Abstract: Circular RNAs (circRNAs) are evolutionarily conserved and widely present, but their functions remain largely unknown. Recent development has highlighted the importance of circRNAs as the sponge of microRNA (miRNA) in cancer. We previously reported that gga-miR-375 was downregulated in the liver tumors of chickens infected with avian leukosis virus subgroup J (ALV-J) by microRNA microarray assay. It can be reasonably assumed in accordance with previous studies that the gga-miR-375 may be related to circRNAs. However, the question as to which circRNA acts as the sponge for gga-miR-375 remains to be answered. In this study, circRNA sequencing results revealed that a circRNA Vav3 termed circ-Vav3 was upregulated in the liver tumors of chickens infected with ALV-J. In addition, RNA immunoprecipitation (RIP), biotinylated RNA pull-down and RNA-fluorescence in situ hybridization (RNA-FISH) experiments were conducted to confirm that circ-Vav3 serves as the sponge of gga-miR-375. Furthermore, we confirmed through dual luciferase reporter assay that YAP1 is the target gene of gga-miR-375. The effect of the sponge function of circ-Vav3 on its downstream genes has been further verified by our conclusion that the sponge function of circ-Vav3 can abrogate gga-miR-375 target gene YAP1 and increase the expression level of YAP1. We further confirmed that the circ-Vav3/gga-miR-375/YAP1 axis induces epithelial-mesenchymal transition (EMT) through influencing EMT markers to promote tumorigenesis. Finally, clinical ALV-J-induced tumor livers were collected to detect core gene expression levels to provide a proof to the concluded tumorigenic mechanism. Together, our results suggest that circ-Vav3/gga-miR-375/YAP1 axis is another regulator of tumorigenesis.