AUTHOR=Xu Haojun , Lin Changjie , Li Ting , Zhu Yifan , Yang Jinghan , Chen Sijie , Chen Jianguo , Chen Xi , Chen Yingyu , Guo Aizhen , Hu Changmin 

TITLE=N6-Methyladenosine-Modified circRNA in the Bovine Mammary Epithelial Cells Injured by Staphylococcus aureus and Escherichia coli

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.873330

DOI=10.3389/fimmu.2022.873330

ISSN=1664-3224

ABSTRACT=<p>Mastitis is a common disease that hinders the development of dairy industry and animal husbandry. It leads to the abuse of antibiotics and the emergence of super drug-resistant bacteria, and poses a great threat to human food health and safety. <italic>Staphylococcus aureus</italic> (<italic>S. aureus</italic>) and <italic>Escherichia coli</italic> (<italic>E. coli</italic>) are the most common pathogens of mastitis in dairy cows and usually cause subclinical or clinical mastitis. CircRNAs and N<sup>6</sup>-methyladenosine (m<sup>6</sup>A) play important roles in immunological diseases. However, the mechanisms by which m<sup>6</sup>A modifies circRNA in bovine mammary epithelial cells remain poorly understood. The aim of our study was to investigate m<sup>6</sup>A-modified circRNAs in bovine mammary epithelial cells (MAC-T cells) injured by <italic>S. aureus</italic> and <italic>E. coli.</italic> The profile of m<sup>6</sup>A-modified circRNA showed a total of 1,599 m<sup>6</sup>A peaks within 1,035 circRNAs in the control group, 35 peaks within 32 circRNAs in the <italic>S. aureus</italic> group, and 1,016 peaks within 728 circRNAs in the <italic>E. coli</italic> group. Compared with the control group, 67 peaks within 63 circRNAs were significantly different in the <italic>S. aureus</italic> group, and 192 peaks within 137 circRNAs were significantly different in the <italic>E. coli</italic> group. Furthermore, we found the source genes of these differentially m<sup>6</sup>A-modified circRNAs in the <italic>S. aureus</italic> and <italic>E. coli</italic> groups with similar functions according to GO and KEGG analyses, which were mainly associated with cell injury, such as inflammation, apoptosis, and autophagy. CircRNA–miRNA–mRNA interaction networks predicted the potential circRNA regulation mechanism in <italic>S. aureus-</italic> and <italic>E. coli</italic>-induced cell injury. We found that the mRNAs in the networks, such as BCL2, MIF, and TNFAIP8L2, greatly participated in the MAPK, WNT, and inflammation pathways. This is the first report on m<sup>6</sup>A-modified circRNA regulation of cells under <italic>S. aureus</italic> and <italic>E. coli</italic> treatment, and sheds new light on potential mechanisms and targets from the perspective of epigenetic modification in mastitis and other inflammatory diseases.</p>