<scp>IFN</scp> ‐γ Targeting the <scp>JAK2</scp> / <scp>STAT3</scp> ‐ <scp>METTL3</scp> Pathway Ameliorates Mandibular Osteogenic Differentiation in Postmenopausal Rats

To investigate whether interferon-gamma (IFN-γ) alleviates postmenopausal osteoporosis (POP) by regulating METTL3 via the JAK2/STAT3 pathway to enhance osteogenic differentiation of jawbone marrow stromal cells (JBMSCs). Ovariectomized (OVX) rats received IFN-γ (5000 IU/dose, 3×/week for 24 weeks), with jawbone mass assessed via micro-CT and HE staining. JBMSCs were cultured, and osteogenic differentiation under IFN-γ (optimal concentration: 10 ng/mL) was evaluated using qRT-PCR, ALP/alizarin red staining, and CCK-8. METTL3's role was analyzed via lentiviral overexpression (OE-METTL3) or knockdown (sh-METTL3). JAK2/STAT3 pathway activity was tested using AG490 (JAK2 inhibitor) and Western blot for phosphorylated JAK2/STAT3. IFN-γ reduced alveolar bone loss in OVX rats, increased osteocytes, and decreased osteoclasts. In JBMSCs, 10 ng/mL IFN-γ upregulated osteogenic genes (Runx2, OPN, OPG) and mineralization. METTL3 expression was elevated by IFN-γ; sh-METTL3 suppressed Runx2, while OE-METTL3 reversed OVX-induced osteogenic inhibition. IFN-γ activated JAK2/STAT3 signaling, but AG490 reduced both osteogenic gene expression and METTL3 levels. METTL3 overexpression amplified JAK2/STAT3 phosphorylation, synergizing with IFN-γ to enhance osteogenesis. IFN-γ activates the JAK2/STAT3 pathway to drive METTL3 transcription, upregulating osteogenic genes and mitigating jawbone loss in POP. METTL3 overexpression counteracts estrogen deficiency-induced osteogenic suppression and forms a positive feedback loop with JAK2/STAT3. AG490's complete blockade of IFN-γ/METTL3 effects confirms the JAK2/STAT3-METTL3 axis as central to bone immune metabolism, highlighting therapeutic potential for targeting this pathway in POP.