STAT5-mediated transcription of miR-33-5p in Mycoplasma gallisepticum-infected DF-1 cells

Mycoplasma gallisepticum (MG) represents the primary causative agent of chronic respiratory disease (CRD) in chickens. CRD is a prevalent ailment in the global poultry industry, resulting in substantial economic losses. In our previous work, we reported that miR-33-5p inhibits MG-induced apoptosis, inflammatory factor production, and MG replication by specifically targeting JNK1 in chickens. Nevertheless, the regulatory mechanisms governing miR-33-5p expression during MG infection remain poorly understood. Therefore, the objective of this study was to explore the regulation of miR-33-5p gene expression during MG infection. In this study, we observed an upregulation in the expression of pri-miR-33-5p and pre-miR-33-5p following MG infection, suggesting that their regulation takes place at the transcriptional level. Moreover, we characterized the transcriptional regulatory region of miR-33-5p and discovered the presence of a binding motif for STAT5, a recognized transcription factor responsible for gene expression regulation. Luciferase reporter assays and mutational analyses unequivocally showed that STAT5 binds to the miR-33-5p promoter element, thereby modulating miR-33-5p transcription in response to MG infection. Ultimately, the overexpression of STAT5 led to an elevation in miR-33-5p expression while concurrently suppressing JNK1 expression. Our findings elucidate that STAT5 governs the upregulation of miR-33-5p during MG infection. This research offers a comprehensive understanding of MG pathogenesis and the exploration of therapeutic approaches for MG-induced CRD.