The effect of octamer-binding transcription factor 4B1 on microRNA signals in human dental pulp cells with inflammatory response.

INTRODUCTION: Dental pulp surrounded by rigid dentin is vulnerable to inflammatory stress; because of this, the invaded bacteria could cause irreversible pulpitis and necrosis. Octamer-binding transcription factor 4B1 (Oct-4B1), a newly discovered Oct-4 spliced variant belonging to the class V of the POU transcription factor family, serves as a precursor of Oct-4B and an essential functional isoform of Oct-4. However, its specific role in the inflammatory response of dental pulp cells (DPCs) remains unknown.

METHODS: To explore the effect of Oct-4B1 on the inflammatory response of DPCs, messenger RNA expression of Oct-4B1 and Oct-4B in DPCs with lipopolysaccharide (LPS) induction was examined by real-time polymerase chain reaction. The expression of Oct-4B1 in DPCs was knocked down by specific small interfering RNA (siRNA); cell proliferation and the apoptosis rate were detected by the Cell Counting Kit-8 (Tokyo, Dojindo, Japan) and Hoechst-propidium iodide staining. The microRNA (miRNA) expression profiles were examined by miRNA microarray and bioinformatic analysis.

RESULTS: We showed the messenger RNA expression of Oct-4B1 and Oct-4B was up-regulated in DPCs with LPS stimulation, whereas the knockdown expression of Oct-4B1 led to down-regulation of Oct-4B and an increased number of apoptotic cells in DPCs with LPS stimulation. Moreover, a total of 38 miRNAs were differentially expressed (including 4 up-regulated and 34 down-regulated) in DPCs with Oct-4B1 knockdown. Six of them were confirmed by real-time polymerase chain reaction, among which the target genes of miR-221 were predicted to be enriched in 14 Kyoto Encyclopedia of Genes and Genomes pathways represented by mitogen-activated protein kinase, Wnt, and Toll-like signaling pathways.

CONCLUSIONS: Oct-4B1 may play a critical role in the inflammatory response of DPCs through interaction with miRNAs.