Upregulated gga-miR-16-5p Inhibits the Proliferation Cycle and Promotes the Apoptosis of MG-Infected DF-1 Cells by Repressing PIK3R1-Mediated the PI3K/Akt/NF-κB Pathway to Exert Anti-Inflammatory Effect

Mycoplasma gallisepticum (MG) mainly infects chickens to initiate chronic respiratory disease (CRD). microRNAs (miRNAs) play vital roles according to previously reported studies. Our previous study showed that gga-miR-16-5p, in MG-infected lungs of chicken embryo, was upregulated by Illumina sequencing. The study aimed to reveal what role gga-miR-16-5p plays in CRD progression. gga-miR-16-5p was upregulated in MG-infected fibroblast cells (DF-1). Phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) was demonstrated as the target gene of gga-miR-16-5p. Furthermore, PIK3R1 expression was lower in MG-infected groups than it in noninfected controls measured by qPCR. Additionally, overexpressed gga-miR-16-5p could downregulate PIK3R1 and phosphorylated serine/threonine kinase (p-Akt) to express protein, whereas there is an opposite effect on inhibition. Overexpressed gga-miR-16-5p resulted in decreased activity of tumor necrosis factor alpha (TNF-α) and the nuclear factor-kappaB (NF-κB) by qPCR. Furthermore, overexpressed gga-miR-16-5p restricted cell multiplication, cycle progression, and increased apoptosis of MG-infected DF-1 cells, whereas inhibited gga-miR-16-5p led to the opposite effect. Collectively, upregulated gga-miR-16-5p could decrease multiplication, cycle progression, and increase apoptosis of MG-infected DF-1 cells, at least partly through directly targeting PIK3R1 and inhibiting PI3K/Akt/NF-κB pathway to exert an anti-inflammatory effect. Our results will provide more experimental evidence to bring pathogenesis of MG infection to light.