LncRNAp21 promotes osteogenic differentiation of mesenchymal stem cells in the rat model of osteoporosis by the Wnt/β-catenin signaling pathway.

OBJECTIVE:The aim of this study was to explore the promoting effect of long non-coding ribonucleic acid p21 (lncRNAp21) on the osteogenic differentiation of mesenchymal stem cells in the rat model of osteoporosis (OP) through the Wnt/β-catenin signaling pathway. MATERIALS AND METHODS:A total of 30 healthy female rats were selected and randomly divided into three groups, including the lncRNAp21 group, OP model group (model group) and normal group. Rats in the lncRNAp21 group were given a certain quantity of lncRNAp21 inhibitors for gavage. Rats in the model group were regularly given 0.9% NaCl for gavage every day after the removal of bilateral ovaries. Meanwhile, rats in the normal group were fed normally without any changes. Bone mineral density (BMD) was measured after 12 weeks of modeling. The levels of procollagen type I N-terminal propeptide (PINP), serum estradiol (E2), osteocalcin (OC), bone alkaline phosphatase (BALP), C-terminal cross-linking telopeptide of type I collagen (CTX) and tartrate-resistant acid phosphatase 5b (TRACP-5b) in the bone and serum of rats were measured by enzyme-linked immunosorbent assay (ELISA). Besides, quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and Western blotting were adopted to detect the mRNA and protein expressions of Wnt1 and β-catenin in bone tissues, respectively. RESULTS:Compared with the normal group and lncRNAp21 group, the serum level of E2 in the model group decreased significantly (p<0.05). BMD and phosphorus (P) content in the model group were both markedly lower than those of the normal group and lncRNAp21 group. However, calcium (Ca) content was remarkably higher than that of the normal group and lncRNAp21 group (p<0.05). The serum levels of bone resorption markers (including TRACP-5b and CTX) in the model group were prominently higher than those of the normal group (p<0.05). However, the levels of the two markers in the lncRNAp21 group were significantly lower than the model group (p<0.05). Additionally, bone formation markers (including OC, PINP and BALP) in the serum of rats in the model group were notably higher than those in the normal group and lncRNAp21 group (p<0.05). QRT-PCR and Western blotting results revealed that the mRNA and protein expressions of Wnt1 and β-catenin in bone tissues of the model group were markedly lower than those of the normal group. However, the mRNA and protein expressions of Wnt1 and β-catenin in the lncRNAp21 group were remarkably higher than the model group (p<0.05). CONCLUSIONS:Low expression of lncRNAp21 activates the Wnt/β-catenin signaling pathway by increasing E2 secretion, eventually stimulating bone formation and increasing osteogenic differentiation of mesenchymal stem cells in OP model rats.