Objective: To observe the effect of transfected microRNA-146a (miR-146a) on expression of interleukin-1 receptor-associated kinase 1 (IRAK-1) and tumor necrosis factor receptor-associated factor 6 (TRAF-6) in alveolar macrophages, and to explore the regulatory mechanism of miR-146a in the inflammatory response of alveolar macrophages.
Methods: Alveolar macrophages NR8383 were cultured and divided into two groups: transfected miR-146a mimic group was transfected 50 nmol/L Pre-miR miR-146a precursors and the negative control group was transfected Cy3-labeled Pre-miR negative control. Cells were collected at 24 hours after transfection. The miR-146a and the mRNA expression of IRAK-1 and TRAF-6 were detected by real-time fluorescent quantitation reverse transcription-polymerase chain reaction (RT-qPCR), and the protein expression of IRAK-1 and TRAF-6 was assayed by Western Blot.
Results: Compared with negative control group, the expression of miR-146a was upregulated by (24.55±6.14) fold compared with miR-146a mimic group (t=-9.353, P=0.001). The mRNA expressions of IRAK-1 and TRAF-6 in miR-146a mimic group were upregulated by (1.16±0.10) fold (t=2.701, P=0.054) and (1.19±0.16) fold (t=2.032, P=0.112) , respectively, compared with that of negative control group, but the protein levels of IRAK-1 and TRAF-6 were decreased by 73.0% (t=-9.353, P=0.001) and 64.1% (t=-6.839, P=0.002), respectively .
Conclusions: miR-146a mimic was successfully transfected into the alveolar macrophage NR8383. The overexpression of miR-146a in alveolar macrophages can down-regulate the expression of IRAK-1 and TRAF-6 in protein translation levels, and its mechanism may be related with inhibition of protein translation.