miR-302a-3p regulates RANKL expression in human mandibular osteoblast-like cells

Receptor activator of nuclear factor kappa-B ligand (RANKL) is important substance during osteoclastogenesis that resulted in alveolar bone loss of periodontitis. MicroRNAs (miRNAs) regulate gene expression in several biological processes including osteoclastogenesis. We investigated the function of microRNA-302a-3p (miR-302a-3p) to regulate receptor activator of nuclear factor kappa-B ligand (RANKL) expression in human mandibular osteoblast-like cells (HMOBs). HMOBs were incubated with prostaglandin E₂ (PGE₂ ) to mimic inflammation, or with PGE₂ and interferon gamma (IFNγ) to mimic homeostasis. MicroRNA (miRNA) profiles related to RANKL expression were demonstrated by PCR array, and miR-302a-3p was identified. Using TargetScanHuman 7.0, a target of miR-302a-3p was predicted. To confirm its function, miR-302a-3p was overexpressed, or silenced, by transfection with miR-302a-3p mimic, or inhibitor, respectively. Level of miR-302a-3p and RANKL mRNA was assessed by qRT-PCR. Soluble RANKL (sRANKL), and membrane-bound RANKL (mRANKL) were measured by ELISA and by Western blot, respectively. When PGE₂ stimulated RANKL in HMOBs, miR-302a-3p was lower than baseline level. However, upregulation of miR-302a-3p is observed when IFNγ suppressed RANKL expression in PGE₂ -stimulated HMOBs. miR-302a-3p was predicted to target PRKACB mRNA encoding the catalytic subunit in cAMP/PKA pathway. Overexpression of miR-302a-3p could decrease RANKL expression during PGE₂ stimulation. In contrast, silencing of miR-302a-3p by its inhibitor increased RANKL expression in PGE₂ -IFNγ conditioned HMOBs. miR-302a-3p regulates RANKL expression in HMOBs within PGE₂ -IFNγ regulatory network.