Diosgenin protects against alveolar bone loss in ovariectomized rats via regulating long non-coding RNAs

The present study assessed the changes in long non-coding (lnc)RNA and mRNA expression profiles when diosgenin (DIO) exerted a potential osteoprotective effect on the alveolar bone of ovariectomized (OVX) rats. Female Wistar rats underwent a sham operation (SHAM group) or ovariectomy. OVX rats were treated using vehicle (OVX group), DIO (DIO group) or estradiol valerate (EV group) for 12 weeks. After treatment, the biomarkers of bone turnover in plasma and the microstructure of alveolar bone were assessed. lncRNA microarrays were applied to assess lncRNA and mRNA expression profiles in alveolar bone in the OVX and DIO group rats. Subsequently, the differentially expressed mRNAs associated with the comprehensive bone metabolism pathway in Ingenuity Pathway Analysis (IPA) were identified and regarded as key mRNAs. Based on some of the key mRNAs and all the differentially expressed lncRNAs, a coexpression network was established and this network was further analyzed to identify the top 6 lncRNAs with the highest closeness scores (pivotal lncRNAs). Finally, 6 modules showing interactions between pivotal lncRNAs and key mRNAs were constructed. All of the pivotal lncRNAs and key mRNAs were validated with reverse transcription-quantitative polymerase chain reaction. The present findings demonstrated that DIO suppressed the loss of alveolar bone in OVX rats, and the changes to the expression of some lncRNAs or mRNAs occurred in the alveolar bone of the rats in the DIO group. Twenty-four key mRNAs were identified during pathway analysis. Furthermore, 8/24 key mRNAs (Ctnnb1, Smad4, Tcf2, Sp7, Il1b, Il1r1, Tnf and Tnfrsf1a) were used to establish a coexpression network, which included 1,656 nodes and 5,341 edges. During network analysis, 6 pivotal lncRNAs (XR_008346, MRuc007iji, MRAK157089, MRAK076413, MRAK143591 and AB036696) were obtained, and 6 modules illustrating pivotal lncRNA-key mRNA interactions were identified. These results revealed that the anti-osteoporotic effect of DIO on alveolar bone may be associated with the promotion of a bone formation process through increasing the signaling of the Wnt and BMPs pathways and the inhibition of the bone resorption process through decreasing stimulators of osteoclastogenesis. To conclude, several pivotal lncRNAs may serve important roles in these processes via regulating some key mRNAs in the bone metabolism pathway.