Identification of several key genes by microarray data analysis of bovine mammary gland epithelial cells challenged with Escherichia coli and Staphylococcus aureus.

This study was aimed at exploring the mechanisms and identifying the key candidate genes associated with S. aureus and E. coli mastitis. A public microarray dataset GSE24560 was downloaded. Differentially expressed genes (DEGs) were screened in E. coli- and S. aureus-infected primary bovine mammary gland epithelial cell (pBMEC) samples, and compared with control samples at 1 h, 6 h, and 24 h. A functional enrichment analysis was performed, and construction of a gene co-expression network was performed based on genes that showed consistent changes over time, which were identified using time series expression analysis. Then, a miRNA/TF regulatory network was constructed based on the genes in the co-expression network. The genes in the miRNA/TF regulatory network were screened for involvement in related diseases. Furthermore, the expression of several selected DEGs was further validated using real-time RT-PCR. In total, 92 and 81 DEGs showed continuous differential expression over time in the E. coli- and S. aureus-inoculated groups. DEGs in the E. coli-inoculated group were associated with the RIG-I-like receptor signaling pathway, and those in the S. aureus-inoculated group were associated with the lysosome pathway. Time series expression analysis identified two gene clusters. NFKBIZ and GRO1 in the gene co-expression network were associated with inflammatory and defense responses. Moreover, several genes such as CXADR, APP, and CXCL2 in the miRNA/TF regulatory network, were associated with infection, inflammation, or stress-related diseases. RIG-I like receptor pathway and several DEGs such as NFKBIZ, GRO1, CXCL2, and CXADR may play critical roles in the response to infection in pBMECs.