Lysine methyltransferase methyltransferase-like 13 regulates bone marrow mesenchymal stem cells osteo-adipogenic differentiation and senescence in osteoporosis via the Foxa1/HES-1 axis.

PURPOSE: Recent research indicates that the senescence of bone marrow mesenchymal stem cells (BMSCs) disrupts the osteo-adipogenic balance, a primary factor contributing to the development of osteoporosis. Our previous findings have implicated methyltransferases in this process, among which methyltransferase-like 13 (METTL13) has been established to regulate cell fate, although its role in osteoporosis has yet to be determined.

METHODS

Bone formation was assessed using micro-computed tomography and hematoxylin and eosin staining. Protein expression in bone tissues was examined immunohistochemically, and cellular mRNA and protein levels were determined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting. Cellular senescence was evaluated based on β-galactosidase staining, and osteogenic and adipogenic differentiation was examined using alkaline phosphatase, Alizarin Red S, and Oil Red O staining. Protein interactions and DNA binding were determined using co-immunoprecipitation and chromatin immunoprecipitation.

RESULTS

METTL13 expression was significantly enhanced in ovariectomy-induced senescent bone and BMSCs, whereas METTL13 knockdown markedly reversed etoposide-induced cellular senescence. By binding to forkhead box protein A1 (Foxa1), METTL13 promotes the preferential differentiation of BMSCs into adipocytes, as opposed to osteocytes. Moreover, Foxa1 had effects opposite to those of METTL13 on BMSC differentiation, inhibiting the nuclear entry of METTL13. Notably, blocking the nuclear import of Foxa1 suppressed the transcriptional expression of HES-1, which promoted the adipogenic differentiation of BMSCs and inhibited osteogenic differentiation.

CONCLUSIONS

Our findings in this study revealed the mechanisms whereby METTL13 promotes BMSC senescence and disrupts BMSC differentiation, on the basis of which, we identified the METTL13-Foxa1-HES-1 axis as a potential therapeutic target for treatment of osteoporosis.